WordPress 4.5

[autoinstalls/wordpress.git] / wp-includes / post.php

<?php
/**
 * Core Post API
 *
 * @package WordPress
 * @subpackage Post
 */

//
// Post Type Registration
//

/**
 * Creates the initial post types when 'init' action is fired.
 *
 * @since 2.9.0
 */
function create_initial_post_types() {
        register_post_type( 'post', array(
                'labels' => array(
                        'name_admin_bar' => _x( 'Post', 'add new on admin bar' ),
                ),
                'public'  => true,
                '_builtin' => true, /* internal use only. don't use this when registering your own post type. */
                '_edit_link' => 'post.php?post=%d', /* internal use only. don't use this when registering your own post type. */
                'capability_type' => 'post',
                'map_meta_cap' => true,
                'menu_position' => 5,
                'hierarchical' => false,
                'rewrite' => false,
                'query_var' => false,
                'delete_with_user' => true,
                'supports' => array( 'title', 'editor', 'author', 'thumbnail', 'excerpt', 'trackbacks', 'custom-fields', 'comments', 'revisions', 'post-formats' ),
        ) );

        register_post_type( 'page', array(
                'labels' => array(
                        'name_admin_bar' => _x( 'Page', 'add new on admin bar' ),
                ),
                'public' => true,
                'publicly_queryable' => false,
                '_builtin' => true, /* internal use only. don't use this when registering your own post type. */
                '_edit_link' => 'post.php?post=%d', /* internal use only. don't use this when registering your own post type. */
                'capability_type' => 'page',
                'map_meta_cap' => true,
                'menu_position' => 20,
                'hierarchical' => true,
                'rewrite' => false,
                'query_var' => false,
                'delete_with_user' => true,
                'supports' => array( 'title', 'editor', 'author', 'thumbnail', 'page-attributes', 'custom-fields', 'comments', 'revisions' ),
        ) );

        register_post_type( 'attachment', array(
                'labels' => array(
                        'name' => _x('Media', 'post type general name'),
                        'name_admin_bar' => _x( 'Media', 'add new from admin bar' ),
                        'add_new' => _x( 'Add New', 'add new media' ),
                        'edit_item' => __( 'Edit Media' ),
                        'view_item' => __( 'View Attachment Page' ),
                ),
                'public' => true,
                'show_ui' => true,
                '_builtin' => true, /* internal use only. don't use this when registering your own post type. */
                '_edit_link' => 'post.php?post=%d', /* internal use only. don't use this when registering your own post type. */
                'capability_type' => 'post',
                'capabilities' => array(
                        'create_posts' => 'upload_files',
                ),
                'map_meta_cap' => true,
                'hierarchical' => false,
                'rewrite' => false,
                'query_var' => false,
                'show_in_nav_menus' => false,
                'delete_with_user' => true,
                'supports' => array( 'title', 'author', 'comments' ),
        ) );
        add_post_type_support( 'attachment:audio', 'thumbnail' );
        add_post_type_support( 'attachment:video', 'thumbnail' );

        register_post_type( 'revision', array(
                'labels' => array(
                        'name' => __( 'Revisions' ),
                        'singular_name' => __( 'Revision' ),
                ),
                'public' => false,
                '_builtin' => true, /* internal use only. don't use this when registering your own post type. */
                '_edit_link' => 'revision.php?revision=%d', /* internal use only. don't use this when registering your own post type. */
                'capability_type' => 'post',
                'map_meta_cap' => true,
                'hierarchical' => false,
                'rewrite' => false,
                'query_var' => false,
                'can_export' => false,
                'delete_with_user' => true,
                'supports' => array( 'author' ),
        ) );

        register_post_type( 'nav_menu_item', array(
                'labels' => array(
                        'name' => __( 'Navigation Menu Items' ),
                        'singular_name' => __( 'Navigation Menu Item' ),
                ),
                'public' => false,
                '_builtin' => true, /* internal use only. don't use this when registering your own post type. */
                'hierarchical' => false,
                'rewrite' => false,
                'delete_with_user' => false,
                'query_var' => false,
        ) );

        register_post_status( 'publish', array(
                'label'       => _x( 'Published', 'post status' ),
                'public'      => true,
                '_builtin'    => true, /* internal use only. */
                'label_count' => _n_noop( 'Published <span class="count">(%s)</span>', 'Published <span class="count">(%s)</span>' ),
        ) );

        register_post_status( 'future', array(
                'label'       => _x( 'Scheduled', 'post status' ),
                'protected'   => true,
                '_builtin'    => true, /* internal use only. */
                'label_count' => _n_noop('Scheduled <span class="count">(%s)</span>', 'Scheduled <span class="count">(%s)</span>' ),
        ) );

        register_post_status( 'draft', array(
                'label'       => _x( 'Draft', 'post status' ),
                'protected'   => true,
                '_builtin'    => true, /* internal use only. */
                'label_count' => _n_noop( 'Draft <span class="count">(%s)</span>', 'Drafts <span class="count">(%s)</span>' ),
        ) );

        register_post_status( 'pending', array(
                'label'       => _x( 'Pending', 'post status' ),
                'protected'   => true,
                '_builtin'    => true, /* internal use only. */
                'label_count' => _n_noop( 'Pending <span class="count">(%s)</span>', 'Pending <span class="count">(%s)</span>' ),
        ) );

        register_post_status( 'private', array(
                'label'       => _x( 'Private', 'post status' ),
                'private'     => true,
                '_builtin'    => true, /* internal use only. */
                'label_count' => _n_noop( 'Private <span class="count">(%s)</span>', 'Private <span class="count">(%s)</span>' ),
        ) );

        register_post_status( 'trash', array(
                'label'       => _x( 'Trash', 'post status' ),
                'internal'    => true,
                '_builtin'    => true, /* internal use only. */
                'label_count' => _n_noop( 'Trash <span class="count">(%s)</span>', 'Trash <span class="count">(%s)</span>' ),
                'show_in_admin_status_list' => true,
        ) );

        register_post_status( 'auto-draft', array(
                'label'    => 'auto-draft',
                'internal' => true,
                '_builtin' => true, /* internal use only. */
        ) );

        register_post_status( 'inherit', array(
                'label'    => 'inherit',
                'internal' => true,
                '_builtin' => true, /* internal use only. */
                'exclude_from_search' => false,
        ) );
}

/**
 * Retrieve attached file path based on attachment ID.
 *
 * By default the path will go through the 'get_attached_file' filter, but
 * passing a true to the $unfiltered argument of get_attached_file() will
 * return the file path unfiltered.
 *
 * The function works by getting the single post meta name, named
 * '_wp_attached_file' and returning it. This is a convenience function to
 * prevent looking up the meta name and provide a mechanism for sending the
 * attached filename through a filter.
 *
 * @since 2.0.0
 *
 * @param int  $attachment_id Attachment ID.
 * @param bool $unfiltered    Optional. Whether to apply filters. Default false.
 * @return string|false The file path to where the attached file should be, false otherwise.
 */
function get_attached_file( $attachment_id, $unfiltered = false ) {
        $file = get_post_meta( $attachment_id, '_wp_attached_file', true );

        // If the file is relative, prepend upload dir.
        if ( $file && 0 !== strpos( $file, '/' ) && ! preg_match( '|^.:\\\|', $file ) && ( ( $uploads = wp_get_upload_dir() ) && false === $uploads['error'] ) ) {
                $file = $uploads['basedir'] . "/$file";
        }

        if ( $unfiltered ) {
                return $file;
        }

        /**
         * Filter the attached file based on the given ID.
         *
         * @since 2.1.0
         *
         * @param string $file          Path to attached file.
         * @param int    $attachment_id Attachment ID.
         */
        return apply_filters( 'get_attached_file', $file, $attachment_id );
}

/**
 * Update attachment file path based on attachment ID.
 *
 * Used to update the file path of the attachment, which uses post meta name
 * '_wp_attached_file' to store the path of the attachment.
 *
 * @since 2.1.0
 *
 * @param int    $attachment_id Attachment ID.
 * @param string $file          File path for the attachment.
 * @return bool True on success, false on failure.
 */
function update_attached_file( $attachment_id, $file ) {
        if ( !get_post( $attachment_id ) )
                return false;

        /**
         * Filter the path to the attached file to update.
         *
         * @since 2.1.0
         *
         * @param string $file          Path to the attached file to update.
         * @param int    $attachment_id Attachment ID.
         */
        $file = apply_filters( 'update_attached_file', $file, $attachment_id );

        if ( $file = _wp_relative_upload_path( $file ) )
                return update_post_meta( $attachment_id, '_wp_attached_file', $file );
        else
                return delete_post_meta( $attachment_id, '_wp_attached_file' );
}

/**
 * Return relative path to an uploaded file.
 *
 * The path is relative to the current upload dir.
 *
 * @since 2.9.0
 *
 * @param string $path Full path to the file.
 * @return string Relative path on success, unchanged path on failure.
 */
function _wp_relative_upload_path( $path ) {
        $new_path = $path;

        $uploads = wp_get_upload_dir();
        if ( 0 === strpos( $new_path, $uploads['basedir'] ) ) {
                        $new_path = str_replace( $uploads['basedir'], '', $new_path );
                        $new_path = ltrim( $new_path, '/' );
        }

        /**
         * Filter the relative path to an uploaded file.
         *
         * @since 2.9.0
         *
         * @param string $new_path Relative path to the file.
         * @param string $path     Full path to the file.
         */
        return apply_filters( '_wp_relative_upload_path', $new_path, $path );
}

/**
 * Retrieve all children of the post parent ID.
 *
 * Normally, without any enhancements, the children would apply to pages. In the
 * context of the inner workings of WordPress, pages, posts, and attachments
 * share the same table, so therefore the functionality could apply to any one
 * of them. It is then noted that while this function does not work on posts, it
 * does not mean that it won't work on posts. It is recommended that you know
 * what context you wish to retrieve the children of.
 *
 * Attachments may also be made the child of a post, so if that is an accurate
 * statement (which needs to be verified), it would then be possible to get
 * all of the attachments for a post. Attachments have since changed since
 * version 2.5, so this is most likely inaccurate, but serves generally as an
 * example of what is possible.
 *
 * The arguments listed as defaults are for this function and also of the
 * {@link get_posts()} function. The arguments are combined with the
 * get_children defaults and are then passed to the {@link get_posts()}
 * function, which accepts additional arguments. You can replace the defaults in
 * this function, listed below and the additional arguments listed in the
 * {@link get_posts()} function.
 *
 * The 'post_parent' is the most important argument and important attention
 * needs to be paid to the $args parameter. If you pass either an object or an
 * integer (number), then just the 'post_parent' is grabbed and everything else
 * is lost. If you don't specify any arguments, then it is assumed that you are
 * in The Loop and the post parent will be grabbed for from the current post.
 *
 * The 'post_parent' argument is the ID to get the children. The 'numberposts'
 * is the amount of posts to retrieve that has a default of '-1', which is
 * used to get all of the posts. Giving a number higher than 0 will only
 * retrieve that amount of posts.
 *
 * The 'post_type' and 'post_status' arguments can be used to choose what
 * criteria of posts to retrieve. The 'post_type' can be anything, but WordPress
 * post types are 'post', 'pages', and 'attachments'. The 'post_status'
 * argument will accept any post status within the write administration panels.
 *
 * @since 2.0.0
 *
 * @see get_posts()
 * @todo Check validity of description.
 *
 * @global WP_Post $post
 *
 * @param mixed  $args   Optional. User defined arguments for replacing the defaults. Default empty.
 * @param string $output Optional. Constant for return type. Accepts OBJECT, ARRAY_A, ARRAY_N.
 *                       Default OBJECT.
 * @return array Array of children, where the type of each element is determined by $output parameter.
 *               Empty array on failure.
 */
function get_children( $args = '', $output = OBJECT ) {
        $kids = array();
        if ( empty( $args ) ) {
                if ( isset( $GLOBALS['post'] ) ) {
                        $args = array('post_parent' => (int) $GLOBALS['post']->post_parent );
                } else {
                        return $kids;
                }
        } elseif ( is_object( $args ) ) {
                $args = array('post_parent' => (int) $args->post_parent );
        } elseif ( is_numeric( $args ) ) {
                $args = array('post_parent' => (int) $args);
        }

        $defaults = array(
                'numberposts' => -1, 'post_type' => 'any',
                'post_status' => 'any', 'post_parent' => 0,
        );

        $r = wp_parse_args( $args, $defaults );

        $children = get_posts( $r );

        if ( ! $children )
                return $kids;

        if ( ! empty( $r['fields'] ) )
                return $children;

        update_post_cache($children);

        foreach ( $children as $key => $child )
                $kids[$child->ID] = $children[$key];

        if ( $output == OBJECT ) {
                return $kids;
        } elseif ( $output == ARRAY_A ) {
                $weeuns = array();
                foreach ( (array) $kids as $kid ) {
                        $weeuns[$kid->ID] = get_object_vars($kids[$kid->ID]);
                }
                return $weeuns;
        } elseif ( $output == ARRAY_N ) {
                $babes = array();
                foreach ( (array) $kids as $kid ) {
                        $babes[$kid->ID] = array_values(get_object_vars($kids[$kid->ID]));
                }
                return $babes;
        } else {
                return $kids;
        }
}

/**
 * Get extended entry info (<!--more-->).
 *
 * There should not be any space after the second dash and before the word
 * 'more'. There can be text or space(s) after the word 'more', but won't be
 * referenced.
 *
 * The returned array has 'main', 'extended', and 'more_text' keys. Main has the text before
 * the `<!--more-->`. The 'extended' key has the content after the
 * `<!--more-->` comment. The 'more_text' key has the custom "Read More" text.
 *
 * @since 1.0.0
 *
 * @param string $post Post content.
 * @return array Post before ('main'), after ('extended'), and custom read more ('more_text').
 */
function get_extended( $post ) {
        //Match the new style more links.
        if ( preg_match('/<!--more(.*?)?-->/', $post, $matches) ) {
                list($main, $extended) = explode($matches[0], $post, 2);
                $more_text = $matches[1];
        } else {
                $main = $post;
                $extended = '';
                $more_text = '';
        }

        //  leading and trailing whitespace.
        $main = preg_replace('/^[\s]*(.*)[\s]*$/', '\\1', $main);
        $extended = preg_replace('/^[\s]*(.*)[\s]*$/', '\\1', $extended);
        $more_text = preg_replace('/^[\s]*(.*)[\s]*$/', '\\1', $more_text);

        return array( 'main' => $main, 'extended' => $extended, 'more_text' => $more_text );
}

/**
 * Retrieves post data given a post ID or post object.
 *
 * See {@link sanitize_post()} for optional $filter values. Also, the parameter
 * $post, must be given as a variable, since it is passed by reference.
 *
 * @since 1.5.1
 *
 * @global WP_Post $post
 *
 * @param int|WP_Post|null $post   Optional. Post ID or post object. Defaults to global $post.
 * @param string           $output Optional, default is Object. Accepts OBJECT, ARRAY_A, or ARRAY_N.
 *                                 Default OBJECT.
 * @param string           $filter Optional. Type of filter to apply. Accepts 'raw', 'edit', 'db',
 *                                 or 'display'. Default 'raw'.
 * @return WP_Post|array|null Type corresponding to $output on success or null on failure.
 *                            When $output is OBJECT, a `WP_Post` instance is returned.
 */
function get_post( $post = null, $output = OBJECT, $filter = 'raw' ) {
        if ( empty( $post ) && isset( $GLOBALS['post'] ) )
                $post = $GLOBALS['post'];

        if ( $post instanceof WP_Post ) {
                $_post = $post;
        } elseif ( is_object( $post ) ) {
                if ( empty( $post->filter ) ) {
                        $_post = sanitize_post( $post, 'raw' );
                        $_post = new WP_Post( $_post );
                } elseif ( 'raw' == $post->filter ) {
                        $_post = new WP_Post( $post );
                } else {
                        $_post = WP_Post::get_instance( $post->ID );
                }
        } else {
                $_post = WP_Post::get_instance( $post );
        }

        if ( ! $_post )
                return null;

        $_post = $_post->filter( $filter );

        if ( $output == ARRAY_A )
                return $_post->to_array();
        elseif ( $output == ARRAY_N )
                return array_values( $_post->to_array() );

        return $_post;
}

/**
 * Retrieve ancestors of a post.
 *
 * @since 2.5.0
 *
 * @param int|WP_Post $post Post ID or post object.
 * @return array Ancestor IDs or empty array if none are found.
 */
function get_post_ancestors( $post ) {
        $post = get_post( $post );

        if ( ! $post || empty( $post->post_parent ) || $post->post_parent == $post->ID )
                return array();

        $ancestors = array();

        $id = $ancestors[] = $post->post_parent;

        while ( $ancestor = get_post( $id ) ) {
                // Loop detection: If the ancestor has been seen before, break.
                if ( empty( $ancestor->post_parent ) || ( $ancestor->post_parent == $post->ID ) || in_array( $ancestor->post_parent, $ancestors ) )
                        break;

                $id = $ancestors[] = $ancestor->post_parent;
        }

        return $ancestors;
}

/**
 * Retrieve data from a post field based on Post ID.
 *
 * Examples of the post field will be, 'post_type', 'post_status', 'post_content',
 * etc and based off of the post object property or key names.
 *
 * The context values are based off of the taxonomy filter functions and
 * supported values are found within those functions.
 *
 * @since 2.3.0
 * @since 4.5.0 The `$post` parameter was made optional.
 *
 * @see sanitize_post_field()
 *
 * @param string      $field   Post field name.
 * @param int|WP_Post $post    Optional. Post ID or post object. Defaults to current post.
 * @param string      $context Optional. How to filter the field. Accepts 'raw', 'edit', 'db',
 *                             or 'display'. Default 'display'.
 * @return string The value of the post field on success, empty string on failure.
 */
function get_post_field( $field, $post = null, $context = 'display' ) {
        $post = get_post( $post );

        if ( !$post )
                return '';

        if ( !isset($post->$field) )
                return '';

        return sanitize_post_field($field, $post->$field, $post->ID, $context);
}

/**
 * Retrieve the mime type of an attachment based on the ID.
 *
 * This function can be used with any post type, but it makes more sense with
 * attachments.
 *
 * @since 2.0.0
 *
 * @param int|WP_Post $ID Optional. Post ID or post object. Default empty.
 * @return string|false The mime type on success, false on failure.
 */
function get_post_mime_type( $ID = '' ) {
        $post = get_post($ID);

        if ( is_object($post) )
                return $post->post_mime_type;

        return false;
}

/**
 * Retrieve the post status based on the Post ID.
 *
 * If the post ID is of an attachment, then the parent post status will be given
 * instead.
 *
 * @since 2.0.0
 *
 * @param int|WP_Post $ID Optional. Post ID or post object. Default empty.
 * @return string|false Post status on success, false on failure.
 */
function get_post_status( $ID = '' ) {
        $post = get_post($ID);

        if ( !is_object($post) )
                return false;

        if ( 'attachment' == $post->post_type ) {
                if ( 'private' == $post->post_status )
                        return 'private';

                // Unattached attachments are assumed to be published.
                if ( ( 'inherit' == $post->post_status ) && ( 0 == $post->post_parent) )
                        return 'publish';

                // Inherit status from the parent.
                if ( $post->post_parent && ( $post->ID != $post->post_parent ) ) {
                        $parent_post_status = get_post_status( $post->post_parent );
                        if ( 'trash' == $parent_post_status ) {
                                return get_post_meta( $post->post_parent, '_wp_trash_meta_status', true );
                        } else {
                                return $parent_post_status;
                        }
                }

        }

        /**
         * Filter the post status.
         *
         * @since 4.4.0
         *
         * @param string  $post_status The post status.
         * @param WP_Post $post        The post object.
         */
        return apply_filters( 'get_post_status', $post->post_status, $post );
}

/**
 * Retrieve all of the WordPress supported post statuses.
 *
 * Posts have a limited set of valid status values, this provides the
 * post_status values and descriptions.
 *
 * @since 2.5.0
 *
 * @return array List of post statuses.
 */
function get_post_statuses() {
        $status = array(
                'draft'   => __( 'Draft' ),
                'pending' => __( 'Pending Review' ),
                'private' => __( 'Private' ),
                'publish' => __( 'Published' )
        );

        return $status;
}

/**
 * Retrieve all of the WordPress support page statuses.
 *
 * Pages have a limited set of valid status values, this provides the
 * post_status values and descriptions.
 *
 * @since 2.5.0
 *
 * @return array List of page statuses.
 */
function get_page_statuses() {
        $status = array(
                'draft'   => __( 'Draft' ),
                'private' => __( 'Private' ),
                'publish' => __( 'Published' )
        );

        return $status;
}

/**
 * Register a post status. Do not use before init.
 *
 * A simple function for creating or modifying a post status based on the
 * parameters given. The function will accept an array (second optional
 * parameter), along with a string for the post status name.
 *
 * Arguments prefixed with an _underscore shouldn't be used by plugins and themes.
 *
 * @since 3.0.0
 * @global array $wp_post_statuses Inserts new post status object into the list
 *
 * @param string $post_status Name of the post status.
 * @param array|string $args {
 *     Optional. Array or string of post status arguments.
 *
 *     @type bool|string $label                     A descriptive name for the post status marked
 *                                                  for translation. Defaults to value of $post_status.
 *     @type bool|array  $label_count               Descriptive text to use for nooped plurals.
 *                                                  Default array of $label, twice
 *     @type bool        $exclude_from_search       Whether to exclude posts with this post status
 *                                                  from search results. Default is value of $internal.
 *     @type bool        $_builtin                  Whether the status is built-in. Core-use only.
 *                                                  Default false.
 *     @type bool        $public                    Whether posts of this status should be shown
 *                                                  in the front end of the site. Default false.
 *     @type bool        $internal                  Whether the status is for internal use only.
 *                                                  Default false.
 *     @type bool        $protected                 Whether posts with this status should be protected.
 *                                                  Default false.
 *     @type bool        $private                   Whether posts with this status should be private.
 *                                                  Default false.
 *     @type bool        $publicly_queryable        Whether posts with this status should be publicly-
 *                                                  queryable. Default is value of $public.
 *     @type bool        $show_in_admin_all_list    Whether to include posts in the edit listing for
 *                                                  their post type. Default is value of $internal.
 *     @type bool        $show_in_admin_status_list Show in the list of statuses with post counts at
 *                                                  the top of the edit listings,
 *                                                  e.g. All (12) | Published (9) | My Custom Status (2)
 *                                                  Default is value of $internal.
 * }
 * @return object
 */
function register_post_status( $post_status, $args = array() ) {
        global $wp_post_statuses;

        if (!is_array($wp_post_statuses))
                $wp_post_statuses = array();

        // Args prefixed with an underscore are reserved for internal use.
        $defaults = array(
                'label' => false,
                'label_count' => false,
                'exclude_from_search' => null,
                '_builtin' => false,
                'public' => null,
                'internal' => null,
                'protected' => null,
                'private' => null,
                'publicly_queryable' => null,
                'show_in_admin_status_list' => null,
                'show_in_admin_all_list' => null,
        );
        $args = wp_parse_args($args, $defaults);
        $args = (object) $args;

        $post_status = sanitize_key($post_status);
        $args->name = $post_status;

        // Set various defaults.
        if ( null === $args->public && null === $args->internal && null === $args->protected && null === $args->private )
                $args->internal = true;

        if ( null === $args->public  )
                $args->public = false;

        if ( null === $args->private  )
                $args->private = false;

        if ( null === $args->protected  )
                $args->protected = false;

        if ( null === $args->internal  )
                $args->internal = false;

        if ( null === $args->publicly_queryable )
                $args->publicly_queryable = $args->public;

        if ( null === $args->exclude_from_search )
                $args->exclude_from_search = $args->internal;

        if ( null === $args->show_in_admin_all_list )
                $args->show_in_admin_all_list = !$args->internal;

        if ( null === $args->show_in_admin_status_list )
                $args->show_in_admin_status_list = !$args->internal;

        if ( false === $args->label )
                $args->label = $post_status;

        if ( false === $args->label_count )
                $args->label_count = array( $args->label, $args->label );

        $wp_post_statuses[$post_status] = $args;

        return $args;
}

/**
 * Retrieve a post status object by name.
 *
 * @since 3.0.0
 *
 * @global array $wp_post_statuses List of post statuses.
 *
 * @see register_post_status()
 *
 * @param string $post_status The name of a registered post status.
 * @return object|null A post status object.
 */
function get_post_status_object( $post_status ) {
        global $wp_post_statuses;

        if ( empty($wp_post_statuses[$post_status]) )
                return null;

        return $wp_post_statuses[$post_status];
}

/**
 * Get a list of post statuses.
 *
 * @since 3.0.0
 *
 * @global array $wp_post_statuses List of post statuses.
 *
 * @see register_post_status()
 *
 * @param array|string $args     Optional. Array or string of post status arguments to compare against
 *                               properties of the global `$wp_post_statuses objects`. Default empty array.
 * @param string       $output   Optional. The type of output to return, either 'names' or 'objects'. Default 'names'.
 * @param string       $operator Optional. The logical operation to perform. 'or' means only one element
 *                               from the array needs to match; 'and' means all elements must match.
 *                               Default 'and'.
 * @return array A list of post status names or objects.
 */
function get_post_stati( $args = array(), $output = 'names', $operator = 'and' ) {
        global $wp_post_statuses;

        $field = ('names' == $output) ? 'name' : false;

        return wp_filter_object_list($wp_post_statuses, $args, $operator, $field);
}

/**
 * Whether the post type is hierarchical.
 *
 * A false return value might also mean that the post type does not exist.
 *
 * @since 3.0.0
 *
 * @see get_post_type_object()
 *
 * @param string $post_type Post type name
 * @return bool Whether post type is hierarchical.
 */
function is_post_type_hierarchical( $post_type ) {
        if ( ! post_type_exists( $post_type ) )
                return false;

        $post_type = get_post_type_object( $post_type );
        return $post_type->hierarchical;
}

/**
 * Check if a post type is registered.
 *
 * @since 3.0.0
 *
 * @see get_post_type_object()
 *
 * @param string $post_type Post type name.
 * @return bool Whether post type is registered.
 */
function post_type_exists( $post_type ) {
        return (bool) get_post_type_object( $post_type );
}

/**
 * Retrieve the post type of the current post or of a given post.
 *
 * @since 2.1.0
 *
 * @param int|WP_Post|null $post Optional. Post ID or post object. Default is global $post.
 * @return string|false          Post type on success, false on failure.
 */
function get_post_type( $post = null ) {
        if ( $post = get_post( $post ) )
                return $post->post_type;

        return false;
}

/**
 * Retrieve a post type object by name.
 *
 * @since 3.0.0
 *
 * @global array $wp_post_types List of post types.
 *
 * @see register_post_type()
 *
 * @param string $post_type The name of a registered post type.
 * @return object|null A post type object.
 */
function get_post_type_object( $post_type ) {
        global $wp_post_types;

        if ( ! is_scalar( $post_type ) || empty( $wp_post_types[ $post_type ] ) ) {
                return null;
        }

        return $wp_post_types[ $post_type ];
}

/**
 * Get a list of all registered post type objects.
 *
 * @since 2.9.0
 *
 * @global array $wp_post_types List of post types.
 *
 * @see register_post_type() for accepted arguments.
 *
 * @param array|string $args     Optional. An array of key => value arguments to match against
 *                               the post type objects. Default empty array.
 * @param string       $output   Optional. The type of output to return. Accepts post type 'names'
 *                               or 'objects'. Default 'names'.
 * @param string       $operator Optional. The logical operation to perform. 'or' means only one
 *                               element from the array needs to match; 'and' means all elements
 *                               must match; 'not' means no elements may match. Default 'and'.
 * @return array A list of post type names or objects.
 */
function get_post_types( $args = array(), $output = 'names', $operator = 'and' ) {
        global $wp_post_types;

        $field = ('names' == $output) ? 'name' : false;

        return wp_filter_object_list($wp_post_types, $args, $operator, $field);
}

/**
 * Register a post type. Do not use before init.
 *
 * A function for creating or modifying a post type based on the
 * parameters given. The function will accept an array (second optional
 * parameter), along with a string for the post type name.
 *
 * @since 2.9.0
 * @since 3.0.0 The `show_ui` argument is now enforced on the new post screen.
 * @since 4.4.0 The `show_ui` argument is now enforced on the post type listing screen and post editing screen.
 *
 * @global array      $wp_post_types List of post types.
 * @global WP_Rewrite $wp_rewrite    Used for default feeds.
 * @global WP         $wp            Used to add query vars.
 *
 * @param string $post_type Post type key, must not exceed 20 characters.
 * @param array|string $args {
 *     Array or string of arguments for registering a post type.
 *
 *     @type string      $label                Name of the post type shown in the menu. Usually plural.
 *                                             Default is value of $labels['name'].
 *     @type array       $labels               An array of labels for this post type. If not set, post
 *                                             labels are inherited for non-hierarchical types and page
 *                                             labels for hierarchical ones. {@see get_post_type_labels()}.
 *     @type string      $description          A short descriptive summary of what the post type is.
 *                                             Default empty.
 *     @type bool        $public               Whether a post type is intended for use publicly either via
 *                                             the admin interface or by front-end users. While the default
 *                                             settings of $exclude_from_search, $publicly_queryable, $show_ui,
 *                                             and $show_in_nav_menus are inherited from public, each does not
 *                                             rely on this relationship and controls a very specific intention.
 *                                             Default false.
 *     @type bool        $hierarchical         Whether the post type is hierarchical (e.g. page). Default false.
 *     @type bool        $exclude_from_search  Whether to exclude posts with this post type from front end search
 *                                             results. Default is the opposite value of $public.
 *     @type bool        $publicly_queryable   Whether queries can be performed on the front end for the post type
 *                                             as part of {@see parse_request()}. Endpoints would include:
 *                                             * ?post_type={post_type_key}
 *                                             * ?{post_type_key}={single_post_slug}
 *                                             * ?{post_type_query_var}={single_post_slug}
 *                                             If not set, the default is inherited from $public.
 *     @type bool        $show_ui              Whether to generate and allow a UI for managing this post type in the
 *                                             admin. Default is value of $public.
 *     @type bool        $show_in_menu         Where to show the post type in the admin menu. To work, $show_ui
 *                                             must be true. If true, the post type is shown in its own top level
 *                                             menu. If false, no menu is shown. If a string of an existing top
 *                                             level menu (eg. 'tools.php' or 'edit.php?post_type=page'), the post
 *                                             type will be placed as a sub-menu of that.
 *                                             Default is value of $show_ui.
 *     @type bool        $show_in_nav_menus    Makes this post type available for selection in navigation menus.
 *                                             Default is value $public.
 *     @type bool        $show_in_admin_bar    Makes this post type available via the admin bar. Default is value
 *                                             of $show_in_menu.
 *     @type int         $menu_position        The position in the menu order the post type should appear. To work,
 *                                             $show_in_menu must be true. Default null (at the bottom).
 *     @type string      $menu_icon            The url to the icon to be used for this menu. Pass a base64-encoded
 *                                             SVG using a data URI, which will be colored to match the color scheme
 *                                             -- this should begin with 'data:image/svg+xml;base64,'. Pass the name
 *                                             of a Dashicons helper class to use a font icon, e.g.
 *                                             'dashicons-chart-pie'. Pass 'none' to leave div.wp-menu-image empty
 *                                             so an icon can be added via CSS. Defaults to use the posts icon.
 *     @type string      $capability_type      The string to use to build the read, edit, and delete capabilities.
 *                                             May be passed as an array to allow for alternative plurals when using
 *                                             this argument as a base to construct the capabilities, e.g.
 *                                             array('story', 'stories'). Default 'post'.
 *     @type array       $capabilities         Array of capabilities for this post type. $capability_type is used
 *                                             as a base to construct capabilities by default.
 *                                             {@see get_post_type_capabilities()}.
 *     @type bool        $map_meta_cap         Whether to use the internal default meta capability handling.
 *                                             Default false.
 *     @type array       $supports             An alias for calling {@see add_post_type_support()} directly.
 *                                             Defaults to array containing 'title' & 'editor'.
 *     @type callable    $register_meta_box_cb Provide a callback function that sets up the meta boxes for the
 *                                             edit form. Do remove_meta_box() and add_meta_box() calls in the
 *                                             callback. Default null.
 *     @type array       $taxonomies           An array of taxonomy identifiers that will be registered for the
 *                                             post type. Taxonomies can be registered later with
 *                                             {@see register_taxonomy()} or {@see register_taxonomy_for_object_type()}.
 *                                             Default empty array.
 *     @type bool|string $has_archive          Whether there should be post type archives, or if a string, the
 *                                             archive slug to use. Will generate the proper rewrite rules if
 *                                             $rewrite is enabled. Default false.
 *     @type bool|array  $rewrite              {
 *         Triggers the handling of rewrites for this post type. To prevent rewrite, set to false.
 *         Defaults to true, using $post_type as slug. To specify rewrite rules, an array can be
 *         passed with any of these keys:
 *
 *         @type string $slug       Customize the permastruct slug. Defaults to $post_type key.
 *         @type bool   $with_front Whether the permastruct should be prepended with WP_Rewrite::$front.
 *                                  Default true.
 *         @type bool   $feeds      Whether the feed permastruct should be built for this post type.
 *                                  Default is value of $has_archive.
 *         @type bool   $pages      Whether the permastruct should provide for pagination. Default true.
 *         @type const  $ep_mask    Endpoint mask to assign. If not specified and permalink_epmask is set,
 *                                  inherits from $permalink_epmask. If not specified and permalink_epmask
 *                                  is not set, defaults to EP_PERMALINK.
 *     }
 *     @type string|bool $query_var            Sets the query_var key for this post type. Defaults to $post_type
 *                                             key. If false, a post type cannot be loaded at
 *                                             ?{query_var}={post_slug}. If specified as a string, the query
 *                                             ?{query_var_string}={post_slug} will be valid.
 *     @type bool        $can_export           Whether to allow this post type to be exported. Default true.
 *     @type bool        $delete_with_user     Whether to delete posts of this type when deleting a user. If true,
 *                                             posts of this type belonging to the user will be moved to trash
 *                                             when then user is deleted. If false, posts of this type belonging
 *                                             to the user will *not* be trashed or deleted. If not set (the default),
 *                                             posts are trashed if post_type_supports('author'). Otherwise posts
 *                                             are not trashed or deleted. Default null.
 *     @type bool        $_builtin             FOR INTERNAL USE ONLY! True if this post type is a native or
 *                                             "built-in" post_type. Default false.
 *     @type string      $_edit_link           FOR INTERNAL USE ONLY! URL segment to use for edit link of
 *                                             this post type. Default 'post.php?post=%d'.
 * }
 * @return object|WP_Error The registered post type object, or an error object.
 */
function register_post_type( $post_type, $args = array() ) {
        global $wp_post_types, $wp_rewrite, $wp;

        if ( ! is_array( $wp_post_types ) ) {
                $wp_post_types = array();
        }

        // Sanitize post type name
        $post_type = sanitize_key( $post_type );
        $args      = wp_parse_args( $args );

        /**
         * Filter the arguments for registering a post type.
         *
         * @since 4.4.0
         *
         * @param array  $args      Array of arguments for registering a post type.
         * @param string $post_type Post type key.
         */
        $args = apply_filters( 'register_post_type_args', $args, $post_type );

        $has_edit_link = ! empty( $args['_edit_link'] );

        // Args prefixed with an underscore are reserved for internal use.
        $defaults = array(
                'labels'               => array(),
                'description'          => '',
                'public'               => false,
                'hierarchical'         => false,
                'exclude_from_search'  => null,
                'publicly_queryable'   => null,
                'show_ui'              => null,
                'show_in_menu'         => null,
                'show_in_nav_menus'    => null,
                'show_in_admin_bar'    => null,
                'menu_position'        => null,
                'menu_icon'            => null,
                'capability_type'      => 'post',
                'capabilities'         => array(),
                'map_meta_cap'         => null,
                'supports'             => array(),
                'register_meta_box_cb' => null,
                'taxonomies'           => array(),
                'has_archive'          => false,
                'rewrite'              => true,
                'query_var'            => true,
                'can_export'           => true,
                'delete_with_user'     => null,
                '_builtin'             => false,
                '_edit_link'           => 'post.php?post=%d',
        );
        $args = array_merge( $defaults, $args );
        $args = (object) $args;

        $args->name = $post_type;

        if ( empty( $post_type ) || strlen( $post_type ) > 20 ) {
                _doing_it_wrong( __FUNCTION__, __( 'Post type names must be between 1 and 20 characters in length.' ), '4.2' );
                return new WP_Error( 'post_type_length_invalid', __( 'Post type names must be between 1 and 20 characters in length.' ) );
        }

        // If not set, default to the setting for public.
        if ( null === $args->publicly_queryable )
                $args->publicly_queryable = $args->public;

        // If not set, default to the setting for public.
        if ( null === $args->show_ui )
                $args->show_ui = $args->public;

        // If not set, default to the setting for show_ui.
        if ( null === $args->show_in_menu || ! $args->show_ui )
                $args->show_in_menu = $args->show_ui;

        // If not set, default to the whether the full UI is shown.
        if ( null === $args->show_in_admin_bar )
                $args->show_in_admin_bar = (bool) $args->show_in_menu;

        // If not set, default to the setting for public.
        if ( null === $args->show_in_nav_menus )
                $args->show_in_nav_menus = $args->public;

        // If not set, default to true if not public, false if public.
        if ( null === $args->exclude_from_search )
                $args->exclude_from_search = !$args->public;

        // Back compat with quirky handling in version 3.0. #14122.
        if ( empty( $args->capabilities ) && null === $args->map_meta_cap && in_array( $args->capability_type, array( 'post', 'page' ) ) )
                $args->map_meta_cap = true;

        // If not set, default to false.
        if ( null === $args->map_meta_cap )
                $args->map_meta_cap = false;

        // If there's no specified edit link and no UI, remove the edit link.
        if ( ! $args->show_ui && ! $has_edit_link ) {
                $args->_edit_link = '';
        }

        $args->cap = get_post_type_capabilities( $args );
        unset( $args->capabilities );

        if ( is_array( $args->capability_type ) )
                $args->capability_type = $args->capability_type[0];

        if ( ! empty( $args->supports ) ) {
                add_post_type_support( $post_type, $args->supports );
                unset( $args->supports );
        } elseif ( false !== $args->supports ) {
                // Add default features
                add_post_type_support( $post_type, array( 'title', 'editor' ) );
        }

        if ( false !== $args->query_var ) {
                if ( true === $args->query_var )
                        $args->query_var = $post_type;
                else
                        $args->query_var = sanitize_title_with_dashes( $args->query_var );

                if ( $wp && is_post_type_viewable( $args ) ) {
                        $wp->add_query_var( $args->query_var );
                }
        }

        if ( false !== $args->rewrite && ( is_admin() || '' != get_option( 'permalink_structure' ) ) ) {
                if ( ! is_array( $args->rewrite ) )
                        $args->rewrite = array();
                if ( empty( $args->rewrite['slug'] ) )
                        $args->rewrite['slug'] = $post_type;
                if ( ! isset( $args->rewrite['with_front'] ) )
                        $args->rewrite['with_front'] = true;
                if ( ! isset( $args->rewrite['pages'] ) )
                        $args->rewrite['pages'] = true;
                if ( ! isset( $args->rewrite['feeds'] ) || ! $args->has_archive )
                        $args->rewrite['feeds'] = (bool) $args->has_archive;
                if ( ! isset( $args->rewrite['ep_mask'] ) ) {
                        if ( isset( $args->permalink_epmask ) )
                                $args->rewrite['ep_mask'] = $args->permalink_epmask;
                        else
                                $args->rewrite['ep_mask'] = EP_PERMALINK;
                }

                if ( $args->hierarchical )
                        add_rewrite_tag( "%$post_type%", '(.+?)', $args->query_var ? "{$args->query_var}=" : "post_type=$post_type&pagename=" );
                else
                        add_rewrite_tag( "%$post_type%", '([^/]+)', $args->query_var ? "{$args->query_var}=" : "post_type=$post_type&name=" );

                if ( $args->has_archive ) {
                        $archive_slug = $args->has_archive === true ? $args->rewrite['slug'] : $args->has_archive;
                        if ( $args->rewrite['with_front'] )
                                $archive_slug = substr( $wp_rewrite->front, 1 ) . $archive_slug;
                        else
                                $archive_slug = $wp_rewrite->root . $archive_slug;

                        add_rewrite_rule( "{$archive_slug}/?$", "index.php?post_type=$post_type", 'top' );
                        if ( $args->rewrite['feeds'] && $wp_rewrite->feeds ) {
                                $feeds = '(' . trim( implode( '|', $wp_rewrite->feeds ) ) . ')';
                                add_rewrite_rule( "{$archive_slug}/feed/$feeds/?$", "index.php?post_type=$post_type" . '&feed=$matches[1]', 'top' );
                                add_rewrite_rule( "{$archive_slug}/$feeds/?$", "index.php?post_type=$post_type" . '&feed=$matches[1]', 'top' );
                        }
                        if ( $args->rewrite['pages'] )
                                add_rewrite_rule( "{$archive_slug}/{$wp_rewrite->pagination_base}/([0-9]{1,})/?$", "index.php?post_type=$post_type" . '&paged=$matches[1]', 'top' );
                }

                $permastruct_args = $args->rewrite;
                $permastruct_args['feed'] = $permastruct_args['feeds'];
                add_permastruct( $post_type, "{$args->rewrite['slug']}/%$post_type%", $permastruct_args );
        }

        // Register the post type meta box if a custom callback was specified.
        if ( $args->register_meta_box_cb )
                add_action( 'add_meta_boxes_' . $post_type, $args->register_meta_box_cb, 10, 1 );

        $args->labels = get_post_type_labels( $args );
        $args->label = $args->labels->name;

        $wp_post_types[ $post_type ] = $args;

        add_action( 'future_' . $post_type, '_future_post_hook', 5, 2 );

        foreach ( $args->taxonomies as $taxonomy ) {
                register_taxonomy_for_object_type( $taxonomy, $post_type );
        }

        /**
         * Fires after a post type is registered.
         *
         * @since 3.3.0
         *
         * @param string $post_type Post type.
         * @param object $args      Arguments used to register the post type.
         */
        do_action( 'registered_post_type', $post_type, $args );

        return $args;
}

/**
 * Unregisters a post type.
 *
 * Can not be used to unregister built-in post types.
 *
 * @since 4.5.0
 *
 * @global WP_Rewrite $wp_rewrite             WordPress rewrite component.
 * @global WP         $wp                     Current WordPress environment instance.
 * @global array      $_wp_post_type_features Used to remove post type features.
 * @global array      $post_type_meta_caps    Used to remove meta capabilities.
 * @global array      $wp_post_types          List of post types.
 *
 * @param string $post_type Post type to unregister.
 * @return bool|WP_Error True on success, WP_Error on failure or if the post type doesn't exist.
 */
function unregister_post_type( $post_type ) {
        if ( ! post_type_exists( $post_type ) ) {
                return new WP_Error( 'invalid_post_type', __( 'Invalid post type' ) );
        }

        $post_type_args = get_post_type_object( $post_type );

        // Do not allow unregistering internal post types.
        if ( $post_type_args->_builtin ) {
                return new WP_Error( 'invalid_post_type', __( 'Unregistering a built-in post type is not allowed' ) );
        }

        global $wp, $wp_rewrite, $_wp_post_type_features, $post_type_meta_caps, $wp_post_types;

        // Remove query var.
        if ( false !== $post_type_args->query_var ) {
                $wp->remove_query_var( $post_type_args->query_var );
        }

        // Remove any rewrite rules, permastructs, and rules.
        if ( false !== $post_type_args->rewrite ) {
                remove_rewrite_tag( "%$post_type%" );
                remove_permastruct( $post_type );
                foreach ( $wp_rewrite->extra_rules_top as $regex => $query ) {
                        if ( false !== strpos( $query, "index.php?post_type=$post_type" ) ) {
                                unset( $wp_rewrite->extra_rules_top[ $regex ] );
                        }
                }
        }

        // Remove registered custom meta capabilities.
        foreach ( $post_type_args->cap as $cap ) {
                unset( $post_type_meta_caps[ $cap ] );
        }

        // Remove all post type support.
        unset( $_wp_post_type_features[ $post_type ] );

        // Unregister the post type meta box if a custom callback was specified.
        if ( $post_type_args->register_meta_box_cb ) {
                remove_action( 'add_meta_boxes_' . $post_type, $post_type_args->register_meta_box_cb );
        }

        // Remove the post type from all taxonomies.
        foreach ( get_object_taxonomies( $post_type ) as $taxonomy ) {
                unregister_taxonomy_for_object_type( $taxonomy, $post_type );
        }

        // Remove the future post hook action.
        remove_action( 'future_' . $post_type, '_future_post_hook', 5 );

        // Remove the post type.
        unset( $wp_post_types[ $post_type ] );

        /**
         * Fires after a post type was unregistered.
         *
         * @since 4.5.0
         *
         * @param string $post_type Post type key.
         */
        do_action( 'unregistered_post_type', $post_type );

        return true;
}

/**
 * Build an object with all post type capabilities out of a post type object
 *
 * Post type capabilities use the 'capability_type' argument as a base, if the
 * capability is not set in the 'capabilities' argument array or if the
 * 'capabilities' argument is not supplied.
 *
 * The capability_type argument can optionally be registered as an array, with
 * the first value being singular and the second plural, e.g. array('story, 'stories')
 * Otherwise, an 's' will be added to the value for the plural form. After
 * registration, capability_type will always be a string of the singular value.
 *
 * By default, seven keys are accepted as part of the capabilities array:
 *
 * - edit_post, read_post, and delete_post are meta capabilities, which are then
 *   generally mapped to corresponding primitive capabilities depending on the
 *   context, which would be the post being edited/read/deleted and the user or
 *   role being checked. Thus these capabilities would generally not be granted
 *   directly to users or roles.
 *
 * - edit_posts - Controls whether objects of this post type can be edited.
 * - edit_others_posts - Controls whether objects of this type owned by other users
 *   can be edited. If the post type does not support an author, then this will
 *   behave like edit_posts.
 * - publish_posts - Controls publishing objects of this post type.
 * - read_private_posts - Controls whether private objects can be read.
 *
 * These four primitive capabilities are checked in core in various locations.
 * There are also seven other primitive capabilities which are not referenced
 * directly in core, except in map_meta_cap(), which takes the three aforementioned
 * meta capabilities and translates them into one or more primitive capabilities
 * that must then be checked against the user or role, depending on the context.
 *
 * - read - Controls whether objects of this post type can be read.
 * - delete_posts - Controls whether objects of this post type can be deleted.
 * - delete_private_posts - Controls whether private objects can be deleted.
 * - delete_published_posts - Controls whether published objects can be deleted.
 * - delete_others_posts - Controls whether objects owned by other users can be
 *   can be deleted. If the post type does not support an author, then this will
 *   behave like delete_posts.
 * - edit_private_posts - Controls whether private objects can be edited.
 * - edit_published_posts - Controls whether published objects can be edited.
 *
 * These additional capabilities are only used in map_meta_cap(). Thus, they are
 * only assigned by default if the post type is registered with the 'map_meta_cap'
 * argument set to true (default is false).
 *
 * @since 3.0.0
 *
 * @see register_post_type()
 * @see map_meta_cap()
 *
 * @param object $args Post type registration arguments.
 * @return object object with all the capabilities as member variables.
 */
function get_post_type_capabilities( $args ) {
        if ( ! is_array( $args->capability_type ) )
                $args->capability_type = array( $args->capability_type, $args->capability_type . 's' );

        // Singular base for meta capabilities, plural base for primitive capabilities.
        list( $singular_base, $plural_base ) = $args->capability_type;

        $default_capabilities = array(
                // Meta capabilities
                'edit_post'          => 'edit_'         . $singular_base,
                'read_post'          => 'read_'         . $singular_base,
                'delete_post'        => 'delete_'       . $singular_base,
                // Primitive capabilities used outside of map_meta_cap():
                'edit_posts'         => 'edit_'         . $plural_base,
                'edit_others_posts'  => 'edit_others_'  . $plural_base,
                'publish_posts'      => 'publish_'      . $plural_base,
                'read_private_posts' => 'read_private_' . $plural_base,
        );

        // Primitive capabilities used within map_meta_cap():
        if ( $args->map_meta_cap ) {
                $default_capabilities_for_mapping = array(
                        'read'                   => 'read',
                        'delete_posts'           => 'delete_'           . $plural_base,
                        'delete_private_posts'   => 'delete_private_'   . $plural_base,
                        'delete_published_posts' => 'delete_published_' . $plural_base,
                        'delete_others_posts'    => 'delete_others_'    . $plural_base,
                        'edit_private_posts'     => 'edit_private_'     . $plural_base,
                        'edit_published_posts'   => 'edit_published_'   . $plural_base,
                );
                $default_capabilities = array_merge( $default_capabilities, $default_capabilities_for_mapping );
        }

        $capabilities = array_merge( $default_capabilities, $args->capabilities );

        // Post creation capability simply maps to edit_posts by default:
        if ( ! isset( $capabilities['create_posts'] ) )
                $capabilities['create_posts'] = $capabilities['edit_posts'];

        // Remember meta capabilities for future reference.
        if ( $args->map_meta_cap )
                _post_type_meta_capabilities( $capabilities );

        return (object) $capabilities;
}

/**
 * Store or return a list of post type meta caps for map_meta_cap().
 *
 * @since 3.1.0
 * @access private
 *
 * @global array $post_type_meta_caps Used to store meta capabilities.
 *
 * @param array $capabilities Post type meta capabilities.
 */
function _post_type_meta_capabilities( $capabilities = null ) {
        global $post_type_meta_caps;

        foreach ( $capabilities as $core => $custom ) {
                if ( in_array( $core, array( 'read_post', 'delete_post', 'edit_post' ) ) ) {
                        $post_type_meta_caps[ $custom ] = $core;
                }
        }
}

/**
 * Build an object with all post type labels out of a post type object
 *
 * Accepted keys of the label array in the post type object:
 *
 * - name - general name for the post type, usually plural. The same and overridden
 *          by $post_type_object->label. Default is Posts/Pages
 * - singular_name - name for one object of this post type. Default is Post/Page
 * - add_new - Default is Add New for both hierarchical and non-hierarchical types.
 *             When internationalizing this string, please use a gettext context
 *             {@link https://codex.wordpress.org/I18n_for_WordPress_Developers#Disambiguation_by_context}
 *             matching your post type. Example: `_x( 'Add New', 'product' );`.
 * - add_new_item - Default is Add New Post/Add New Page.
 * - edit_item - Default is Edit Post/Edit Page.
 * - new_item - Default is New Post/New Page.
 * - view_item - Default is View Post/View Page.
 * - search_items - Default is Search Posts/Search Pages.
 * - not_found - Default is No posts found/No pages found.
 * - not_found_in_trash - Default is No posts found in Trash/No pages found in Trash.
 * - parent_item_colon - This string isn't used on non-hierarchical types. In hierarchical
 * ones the default is 'Parent Page:'.
 * - all_items - String for the submenu. Default is All Posts/All Pages.
 * - archives - String for use with archives in nav menus. Default is Post Archives/Page Archives.
 * - insert_into_item - String for the media frame button. Default is Insert into post/Insert into page.
 * - uploaded_to_this_item - String for the media frame filter. Default is Uploaded to this post/Uploaded to this page.
 * - featured_image - Default is Featured Image.
 * - set_featured_image - Default is Set featured image.
 * - remove_featured_image - Default is Remove featured image.
 * - use_featured_image - Default is Use as featured image.
 * - menu_name - Default is the same as `name`.
 * - filter_items_list - String for the table views hidden heading.
 * - items_list_navigation - String for the table pagination hidden heading.
 * - items_list - String for the table hidden heading.
 *
 * Above, the first default value is for non-hierarchical post types (like posts)
 * and the second one is for hierarchical post types (like pages).
 *
 * @since 3.0.0
 * @since 4.3.0 Added the `featured_image`, `set_featured_image`, `remove_featured_image`,
 *              and `use_featured_image` labels.
 * @since 4.4.0 Added the `insert_into_item`, `uploaded_to_this_item`, `filter_items_list`,
 *              `items_list_navigation`, and `items_list` labels.
 *
 * @access private
 *
 * @param object $post_type_object Post type object.
 * @return object object with all the labels as member variables.
 */
function get_post_type_labels( $post_type_object ) {
        $nohier_vs_hier_defaults = array(
                'name' => array( _x('Posts', 'post type general name'), _x('Pages', 'post type general name') ),
                'singular_name' => array( _x('Post', 'post type singular name'), _x('Page', 'post type singular name') ),
                'add_new' => array( _x('Add New', 'post'), _x('Add New', 'page') ),
                'add_new_item' => array( __('Add New Post'), __('Add New Page') ),
                'edit_item' => array( __('Edit Post'), __('Edit Page') ),
                'new_item' => array( __('New Post'), __('New Page') ),
                'view_item' => array( __('View Post'), __('View Page') ),
                'search_items' => array( __('Search Posts'), __('Search Pages') ),
                'not_found' => array( __('No posts found.'), __('No pages found.') ),
                'not_found_in_trash' => array( __('No posts found in Trash.'), __('No pages found in Trash.') ),
                'parent_item_colon' => array( null, __('Parent Page:') ),
                'all_items' => array( __( 'All Posts' ), __( 'All Pages' ) ),
                'archives' => array( __( 'Post Archives' ), __( 'Page Archives' ) ),
                'insert_into_item' => array( __( 'Insert into post' ), __( 'Insert into page' ) ),
                'uploaded_to_this_item' => array( __( 'Uploaded to this post' ), __( 'Uploaded to this page' ) ),
                'featured_image' => array( __( 'Featured Image' ), __( 'Featured Image' ) ),
                'set_featured_image' => array( __( 'Set featured image' ), __( 'Set featured image' ) ),
                'remove_featured_image' => array( __( 'Remove featured image' ), __( 'Remove featured image' ) ),
                'use_featured_image' => array( __( 'Use as featured image' ), __( 'Use as featured image' ) ),
                'filter_items_list' => array( __( 'Filter posts list' ), __( 'Filter pages list' ) ),
                'items_list_navigation' => array( __( 'Posts list navigation' ), __( 'Pages list navigation' ) ),
                'items_list' => array( __( 'Posts list' ), __( 'Pages list' ) ),
        );
        $nohier_vs_hier_defaults['menu_name'] = $nohier_vs_hier_defaults['name'];

        $labels = _get_custom_object_labels( $post_type_object, $nohier_vs_hier_defaults );

        $post_type = $post_type_object->name;

        $default_labels = clone $labels;

        /**
         * Filter the labels of a specific post type.
         *
         * The dynamic portion of the hook name, `$post_type`, refers to
         * the post type slug.
         *
         * @since 3.5.0
         *
         * @see get_post_type_labels() for the full list of labels.
         *
         * @param object $labels Object with labels for the post type as member variables.
         */
        $labels = apply_filters( "post_type_labels_{$post_type}", $labels );

        // Ensure that the filtered labels contain all required default values.
        $labels = (object) array_merge( (array) $default_labels, (array) $labels );

        return $labels;
}

/**
 * Build an object with custom-something object (post type, taxonomy) labels
 * out of a custom-something object
 *
 * @since 3.0.0
 * @access private
 *
 * @param object $object                  A custom-something object.
 * @param array  $nohier_vs_hier_defaults Hierarchical vs non-hierarchical default labels.
 * @return object Object containing labels for the given custom-something object.
 */
function _get_custom_object_labels( $object, $nohier_vs_hier_defaults ) {
        $object->labels = (array) $object->labels;

        if ( isset( $object->label ) && empty( $object->labels['name'] ) )
                $object->labels['name'] = $object->label;

        if ( !isset( $object->labels['singular_name'] ) && isset( $object->labels['name'] ) )
                $object->labels['singular_name'] = $object->labels['name'];

        if ( ! isset( $object->labels['name_admin_bar'] ) )
                $object->labels['name_admin_bar'] = isset( $object->labels['singular_name'] ) ? $object->labels['singular_name'] : $object->name;

        if ( !isset( $object->labels['menu_name'] ) && isset( $object->labels['name'] ) )
                $object->labels['menu_name'] = $object->labels['name'];

        if ( !isset( $object->labels['all_items'] ) && isset( $object->labels['menu_name'] ) )
                $object->labels['all_items'] = $object->labels['menu_name'];

        if ( !isset( $object->labels['archives'] ) && isset( $object->labels['all_items'] ) ) {
                $object->labels['archives'] = $object->labels['all_items'];
        }

        $defaults = array();
        foreach ( $nohier_vs_hier_defaults as $key => $value ) {
                $defaults[$key] = $object->hierarchical ? $value[1] : $value[0];
        }
        $labels = array_merge( $defaults, $object->labels );
        $object->labels = (object) $object->labels;

        return (object) $labels;
}

/**
 * Add submenus for post types.
 *
 * @access private
 * @since 3.1.0
 */
function _add_post_type_submenus() {
        foreach ( get_post_types( array( 'show_ui' => true ) ) as $ptype ) {
                $ptype_obj = get_post_type_object( $ptype );
                // Sub-menus only.
                if ( ! $ptype_obj->show_in_menu || $ptype_obj->show_in_menu === true )
                        continue;
                add_submenu_page( $ptype_obj->show_in_menu, $ptype_obj->labels->name, $ptype_obj->labels->all_items, $ptype_obj->cap->edit_posts, "edit.php?post_type=$ptype" );
        }
}

/**
 * Register support of certain features for a post type.
 *
 * All core features are directly associated with a functional area of the edit
 * screen, such as the editor or a meta box. Features include: 'title', 'editor',
 * 'comments', 'revisions', 'trackbacks', 'author', 'excerpt', 'page-attributes',
 * 'thumbnail', 'custom-fields', and 'post-formats'.
 *
 * Additionally, the 'revisions' feature dictates whether the post type will
 * store revisions, and the 'comments' feature dictates whether the comments
 * count will show on the edit screen.
 *
 * @since 3.0.0
 *
 * @global array $_wp_post_type_features
 *
 * @param string       $post_type The post type for which to add the feature.
 * @param string|array $feature   The feature being added, accepts an array of
 *                                feature strings or a single string.
 */
function add_post_type_support( $post_type, $feature ) {
        global $_wp_post_type_features;

        $features = (array) $feature;
        foreach ($features as $feature) {
                if ( func_num_args() == 2 )
                        $_wp_post_type_features[$post_type][$feature] = true;
                else
                        $_wp_post_type_features[$post_type][$feature] = array_slice( func_get_args(), 2 );
        }
}

/**
 * Remove support for a feature from a post type.
 *
 * @since 3.0.0
 *
 * @global array $_wp_post_type_features
 *
 * @param string $post_type The post type for which to remove the feature.
 * @param string $feature   The feature being removed.
 */
function remove_post_type_support( $post_type, $feature ) {
        global $_wp_post_type_features;

        unset( $_wp_post_type_features[ $post_type ][ $feature ] );
}

/**
 * Get all the post type features
 *
 * @since 3.4.0
 *
 * @global array $_wp_post_type_features
 *
 * @param string $post_type The post type.
 * @return array Post type supports list.
 */
function get_all_post_type_supports( $post_type ) {
        global $_wp_post_type_features;

        if ( isset( $_wp_post_type_features[$post_type] ) )
                return $_wp_post_type_features[$post_type];

        return array();
}

/**
 * Check a post type's support for a given feature.
 *
 * @since 3.0.0
 *
 * @global array $_wp_post_type_features
 *
 * @param string $post_type The post type being checked.
 * @param string $feature   The feature being checked.
 * @return bool Whether the post type supports the given feature.
 */
function post_type_supports( $post_type, $feature ) {
        global $_wp_post_type_features;

        return ( isset( $_wp_post_type_features[$post_type][$feature] ) );
}

/**
 * Retrieves a list of post type names that support a specific feature.
 *
 * @since 4.5.0
 *
 * @global array $_wp_post_type_features Post type features
 *
 * @param array|string $feature  Single feature or an array of features the post types should support.
 * @param string       $operator Optional. The logical operation to perform. 'or' means
 *                               only one element from the array needs to match; 'and'
 *                               means all elements must match; 'not' means no elements may
 *                               match. Default 'and'.
 * @return array A list of post type names.
 */
function get_post_types_by_support( $feature, $operator = 'and' ) {
        global $_wp_post_type_features;

        $features = array_fill_keys( (array) $feature, true );

        return array_keys( wp_filter_object_list( $_wp_post_type_features, $features, $operator ) );
}

/**
 * Update the post type for the post ID.
 *
 * The page or post cache will be cleaned for the post ID.
 *
 * @since 2.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int    $post_id   Optional. Post ID to change post type. Default 0.
 * @param string $post_type Optional. Post type. Accepts 'post' or 'page' to
 *                          name a few. Default 'post'.
 * @return int|false Amount of rows changed. Should be 1 for success and 0 for failure.
 */
function set_post_type( $post_id = 0, $post_type = 'post' ) {
        global $wpdb;

        $post_type = sanitize_post_field('post_type', $post_type, $post_id, 'db');
        $return = $wpdb->update( $wpdb->posts, array('post_type' => $post_type), array('ID' => $post_id) );

        clean_post_cache( $post_id );

        return $return;
}

/**
 * Determines whether a post type is considered "viewable".
 *
 * For built-in post types such as posts and pages, the 'public' value will be evaluated.
 * For all others, the 'publicly_queryable' value will be used.
 *
 * @since 4.4.0
 * @since 4.5.0 Added the ability to pass a post type name in addition to object.
 *
 * @param object $post_type Post type name or object.
 * @return bool Whether the post type should be considered viewable.
 */
function is_post_type_viewable( $post_type ) {
        if ( is_scalar( $post_type ) ) {
                $post_type = get_post_type_object( $post_type );
                if ( ! $post_type ) {
                        return false;
                }
        }

        return $post_type->publicly_queryable || ( $post_type->_builtin && $post_type->public );
}

/**
 * Retrieve list of latest posts or posts matching criteria.
 *
 * The defaults are as follows:
 *
 * @since 1.2.0
 *
 * @see WP_Query::parse_query()
 *
 * @param array $args {
 *     Optional. Arguments to retrieve posts. See WP_Query::parse_query() for all
 *     available arguments.
 *
 *     @type int        $numberposts      Total number of posts to retrieve. Is an alias of $posts_per_page
 *                                        in WP_Query. Accepts -1 for all. Default 5.
 *     @type int|string $category         Category ID or comma-separated list of IDs (this or any children).
 *                                        Is an alias of $cat in WP_Query. Default 0.
 *     @type array      $include          An array of post IDs to retrieve, sticky posts will be included.
 *                                        Is an alias of $post__in in WP_Query. Default empty array.
 *     @type array      $exclude          An array of post IDs not to retrieve. Default empty array.
 *     @type bool       $suppress_filters Whether to suppress filters. Default true.
 * }
 * @return array List of posts.
 */
function get_posts( $args = null ) {
        $defaults = array(
                'numberposts' => 5,
                'category' => 0, 'orderby' => 'date',
                'order' => 'DESC', 'include' => array(),
                'exclude' => array(), 'meta_key' => '',
                'meta_value' =>'', 'post_type' => 'post',
                'suppress_filters' => true
        );

        $r = wp_parse_args( $args, $defaults );
        if ( empty( $r['post_status'] ) )
                $r['post_status'] = ( 'attachment' == $r['post_type'] ) ? 'inherit' : 'publish';
        if ( ! empty($r['numberposts']) && empty($r['posts_per_page']) )
                $r['posts_per_page'] = $r['numberposts'];
        if ( ! empty($r['category']) )
                $r['cat'] = $r['category'];
        if ( ! empty($r['include']) ) {
                $incposts = wp_parse_id_list( $r['include'] );
                $r['posts_per_page'] = count($incposts);  // only the number of posts included
                $r['post__in'] = $incposts;
        } elseif ( ! empty($r['exclude']) )
                $r['post__not_in'] = wp_parse_id_list( $r['exclude'] );

        $r['ignore_sticky_posts'] = true;
        $r['no_found_rows'] = true;

        $get_posts = new WP_Query;
        return $get_posts->query($r);

}

//
// Post meta functions
//

/**
 * Add meta data field to a post.
 *
 * Post meta data is called "Custom Fields" on the Administration Screen.
 *
 * @since 1.5.0
 *
 * @param int    $post_id    Post ID.
 * @param string $meta_key   Metadata name.
 * @param mixed  $meta_value Metadata value. Must be serializable if non-scalar.
 * @param bool   $unique     Optional. Whether the same key should not be added.
 *                           Default false.
 * @return int|false Meta ID on success, false on failure.
 */
function add_post_meta( $post_id, $meta_key, $meta_value, $unique = false ) {
        // Make sure meta is added to the post, not a revision.
        if ( $the_post = wp_is_post_revision($post_id) )
                $post_id = $the_post;

        return add_metadata('post', $post_id, $meta_key, $meta_value, $unique);
}

/**
 * Remove metadata matching criteria from a post.
 *
 * You can match based on the key, or key and value. Removing based on key and
 * value, will keep from removing duplicate metadata with the same key. It also
 * allows removing all metadata matching key, if needed.
 *
 * @since 1.5.0
 *
 * @param int    $post_id    Post ID.
 * @param string $meta_key   Metadata name.
 * @param mixed  $meta_value Optional. Metadata value. Must be serializable if
 *                           non-scalar. Default empty.
 * @return bool True on success, false on failure.
 */
function delete_post_meta( $post_id, $meta_key, $meta_value = '' ) {
        // Make sure meta is added to the post, not a revision.
        if ( $the_post = wp_is_post_revision($post_id) )
                $post_id = $the_post;

        return delete_metadata('post', $post_id, $meta_key, $meta_value);
}

/**
 * Retrieve post meta field for a post.
 *
 * @since 1.5.0
 *
 * @param int    $post_id Post ID.
 * @param string $key     Optional. The meta key to retrieve. By default, returns
 *                        data for all keys. Default empty.
 * @param bool   $single  Optional. Whether to return a single value. Default false.
 * @return mixed Will be an array if $single is false. Will be value of meta data
 *               field if $single is true.
 */
function get_post_meta( $post_id, $key = '', $single = false ) {
        return get_metadata('post', $post_id, $key, $single);
}

/**
 * Update post meta field based on post ID.
 *
 * Use the $prev_value parameter to differentiate between meta fields with the
 * same key and post ID.
 *
 * If the meta field for the post does not exist, it will be added.
 *
 * @since 1.5.0
 *
 * @param int    $post_id    Post ID.
 * @param string $meta_key   Metadata key.
 * @param mixed  $meta_value Metadata value. Must be serializable if non-scalar.
 * @param mixed  $prev_value Optional. Previous value to check before removing.
 *                           Default empty.
 * @return int|bool Meta ID if the key didn't exist, true on successful update,
 *                  false on failure.
 */
function update_post_meta( $post_id, $meta_key, $meta_value, $prev_value = '' ) {
        // Make sure meta is added to the post, not a revision.
        if ( $the_post = wp_is_post_revision($post_id) )
                $post_id = $the_post;

        return update_metadata('post', $post_id, $meta_key, $meta_value, $prev_value);
}

/**
 * Delete everything from post meta matching meta key.
 *
 * @since 2.3.0
 *
 * @param string $post_meta_key Key to search for when deleting.
 * @return bool Whether the post meta key was deleted from the database.
 */
function delete_post_meta_by_key( $post_meta_key ) {
        return delete_metadata( 'post', null, $post_meta_key, '', true );
}

/**
 * Retrieve post meta fields, based on post ID.
 *
 * The post meta fields are retrieved from the cache where possible,
 * so the function is optimized to be called more than once.
 *
 * @since 1.2.0
 *
 * @param int $post_id Optional. Post ID. Default is ID of the global $post.
 * @return array Post meta for the given post.
 */
function get_post_custom( $post_id = 0 ) {
        $post_id = absint( $post_id );
        if ( ! $post_id )
                $post_id = get_the_ID();

        return get_post_meta( $post_id );
}

/**
 * Retrieve meta field names for a post.
 *
 * If there are no meta fields, then nothing (null) will be returned.
 *
 * @since 1.2.0
 *
 * @param int $post_id Optional. Post ID. Default is ID of the global $post.
 * @return array|void Array of the keys, if retrieved.
 */
function get_post_custom_keys( $post_id = 0 ) {
        $custom = get_post_custom( $post_id );

        if ( !is_array($custom) )
                return;

        if ( $keys = array_keys($custom) )
                return $keys;
}

/**
 * Retrieve values for a custom post field.
 *
 * The parameters must not be considered optional. All of the post meta fields
 * will be retrieved and only the meta field key values returned.
 *
 * @since 1.2.0
 *
 * @param string $key     Optional. Meta field key. Default empty.
 * @param int    $post_id Optional. Post ID. Default is ID of the global $post.
 * @return array|null Meta field values.
 */
function get_post_custom_values( $key = '', $post_id = 0 ) {
        if ( !$key )
                return null;

        $custom = get_post_custom($post_id);

        return isset($custom[$key]) ? $custom[$key] : null;
}

/**
 * Check if post is sticky.
 *
 * Sticky posts should remain at the top of The Loop. If the post ID is not
 * given, then The Loop ID for the current post will be used.
 *
 * @since 2.7.0
 *
 * @param int $post_id Optional. Post ID. Default is ID of the global $post.
 * @return bool Whether post is sticky.
 */
function is_sticky( $post_id = 0 ) {
        $post_id = absint( $post_id );

        if ( ! $post_id )
                $post_id = get_the_ID();

        $stickies = get_option( 'sticky_posts' );

        if ( ! is_array( $stickies ) )
                return false;

        if ( in_array( $post_id, $stickies ) )
                return true;

        return false;
}

/**
 * Sanitize every post field.
 *
 * If the context is 'raw', then the post object or array will get minimal
 * sanitization of the integer fields.
 *
 * @since 2.3.0
 *
 * @see sanitize_post_field()
 *
 * @param object|WP_Post|array $post    The Post Object or Array
 * @param string               $context Optional. How to sanitize post fields.
 *                                      Accepts 'raw', 'edit', 'db', or 'display'.
 *                                      Default 'display'.
 * @return object|WP_Post|array The now sanitized Post Object or Array (will be the
 *                              same type as $post).
 */
function sanitize_post( $post, $context = 'display' ) {
        if ( is_object($post) ) {
                // Check if post already filtered for this context.
                if ( isset($post->filter) && $context == $post->filter )
                        return $post;
                if ( !isset($post->ID) )
                        $post->ID = 0;
                foreach ( array_keys(get_object_vars($post)) as $field )
                        $post->$field = sanitize_post_field($field, $post->$field, $post->ID, $context);
                $post->filter = $context;
        } elseif ( is_array( $post ) ) {
                // Check if post already filtered for this context.
                if ( isset($post['filter']) && $context == $post['filter'] )
                        return $post;
                if ( !isset($post['ID']) )
                        $post['ID'] = 0;
                foreach ( array_keys($post) as $field )
                        $post[$field] = sanitize_post_field($field, $post[$field], $post['ID'], $context);
                $post['filter'] = $context;
        }
        return $post;
}

/**
 * Sanitize post field based on context.
 *
 * Possible context values are:  'raw', 'edit', 'db', 'display', 'attribute' and
 * 'js'. The 'display' context is used by default. 'attribute' and 'js' contexts
 * are treated like 'display' when calling filters.
 *
 * @since 2.3.0
 * @since 4.4.0 Like `sanitize_post()`, `$context` defaults to 'display'.
 *
 * @param string $field   The Post Object field name.
 * @param mixed  $value   The Post Object value.
 * @param int    $post_id Post ID.
 * @param string $context Optional. How to sanitize post fields. Looks for 'raw', 'edit',
 *                        'db', 'display', 'attribute' and 'js'. Default 'display'.
 * @return mixed Sanitized value.
 */
function sanitize_post_field( $field, $value, $post_id, $context = 'display' ) {
        $int_fields = array('ID', 'post_parent', 'menu_order');
        if ( in_array($field, $int_fields) )
                $value = (int) $value;

        // Fields which contain arrays of integers.
        $array_int_fields = array( 'ancestors' );
        if ( in_array($field, $array_int_fields) ) {
                $value = array_map( 'absint', $value);
                return $value;
        }

        if ( 'raw' == $context )
                return $value;

        $prefixed = false;
        if ( false !== strpos($field, 'post_') ) {
                $prefixed = true;
                $field_no_prefix = str_replace('post_', '', $field);
        }

        if ( 'edit' == $context ) {
                $format_to_edit = array('post_content', 'post_excerpt', 'post_title', 'post_password');

                if ( $prefixed ) {

                        /**
                         * Filter the value of a specific post field to edit.
                         *
                         * The dynamic portion of the hook name, `$field`, refers to the post
                         * field name.
                         *
                         * @since 2.3.0
                         *
                         * @param mixed $value   Value of the post field.
                         * @param int   $post_id Post ID.
                         */
                        $value = apply_filters( "edit_{$field}", $value, $post_id );

                        /**
                         * Filter the value of a specific post field to edit.
                         *
                         * The dynamic portion of the hook name, `$field_no_prefix`, refers to
                         * the post field name.
                         *
                         * @since 2.3.0
                         *
                         * @param mixed $value   Value of the post field.
                         * @param int   $post_id Post ID.
                         */
                        $value = apply_filters( "{$field_no_prefix}_edit_pre", $value, $post_id );
                } else {
                        $value = apply_filters( "edit_post_{$field}", $value, $post_id );
                }

                if ( in_array($field, $format_to_edit) ) {
                        if ( 'post_content' == $field )
                                $value = format_to_edit($value, user_can_richedit());
                        else
                                $value = format_to_edit($value);
                } else {
                        $value = esc_attr($value);
                }
        } elseif ( 'db' == $context ) {
                if ( $prefixed ) {

                        /**
                         * Filter the value of a specific post field before saving.
                         *
                         * The dynamic portion of the hook name, `$field`, refers to the post
                         * field name.
                         *
                         * @since 2.3.0
                         *
                         * @param mixed $value Value of the post field.
                         */
                        $value = apply_filters( "pre_{$field}", $value );

                        /**
                         * Filter the value of a specific field before saving.
                         *
                         * The dynamic portion of the hook name, `$field_no_prefix`, refers
                         * to the post field name.
                         *
                         * @since 2.3.0
                         *
                         * @param mixed $value Value of the post field.
                         */
                        $value = apply_filters( "{$field_no_prefix}_save_pre", $value );
                } else {
                        $value = apply_filters( "pre_post_{$field}", $value );

                        /**
                         * Filter the value of a specific post field before saving.
                         *
                         * The dynamic portion of the hook name, `$field`, refers to the post
                         * field name.
                         *
                         * @since 2.3.0
                         *
                         * @param mixed $value Value of the post field.
                         */
                        $value = apply_filters( "{$field}_pre", $value );
                }
        } else {

                // Use display filters by default.
                if ( $prefixed ) {

                        /**
                         * Filter the value of a specific post field for display.
                         *
                         * The dynamic portion of the hook name, `$field`, refers to the post
                         * field name.
                         *
                         * @since 2.3.0
                         *
                         * @param mixed  $value   Value of the prefixed post field.
                         * @param int    $post_id Post ID.
                         * @param string $context Context for how to sanitize the field. Possible
                         *                        values include 'raw', 'edit', 'db', 'display',
                         *                        'attribute' and 'js'.
                         */
                        $value = apply_filters( $field, $value, $post_id, $context );
                } else {
                        $value = apply_filters( "post_{$field}", $value, $post_id, $context );
                }
        }

        if ( 'attribute' == $context )
                $value = esc_attr($value);
        elseif ( 'js' == $context )
                $value = esc_js($value);

        return $value;
}

/**
 * Make a post sticky.
 *
 * Sticky posts should be displayed at the top of the front page.
 *
 * @since 2.7.0
 *
 * @param int $post_id Post ID.
 */
function stick_post( $post_id ) {
        $stickies = get_option('sticky_posts');

        if ( !is_array($stickies) )
                $stickies = array($post_id);

        if ( ! in_array($post_id, $stickies) )
                $stickies[] = $post_id;

        update_option('sticky_posts', $stickies);
}

/**
 * Un-stick a post.
 *
 * Sticky posts should be displayed at the top of the front page.
 *
 * @since 2.7.0
 *
 * @param int $post_id Post ID.
 */
function unstick_post( $post_id ) {
        $stickies = get_option('sticky_posts');

        if ( !is_array($stickies) )
                return;

        if ( ! in_array($post_id, $stickies) )
                return;

        $offset = array_search($post_id, $stickies);
        if ( false === $offset )
                return;

        array_splice($stickies, $offset, 1);

        update_option('sticky_posts', $stickies);
}

/**
 * Return the cache key for wp_count_posts() based on the passed arguments.
 *
 * @since 3.9.0
 *
 * @param string $type Optional. Post type to retrieve count Default 'post'.
 * @param string $perm Optional. 'readable' or empty. Default empty.
 * @return string The cache key.
 */
function _count_posts_cache_key( $type = 'post', $perm = '' ) {
        $cache_key = 'posts-' . $type;
        if ( 'readable' == $perm && is_user_logged_in() ) {
                $post_type_object = get_post_type_object( $type );
                if ( $post_type_object && ! current_user_can( $post_type_object->cap->read_private_posts ) ) {
                        $cache_key .= '_' . $perm . '_' . get_current_user_id();
                }
        }
        return $cache_key;
}

/**
 * Count number of posts of a post type and if user has permissions to view.
 *
 * This function provides an efficient method of finding the amount of post's
 * type a blog has. Another method is to count the amount of items in
 * get_posts(), but that method has a lot of overhead with doing so. Therefore,
 * when developing for 2.5+, use this function instead.
 *
 * The $perm parameter checks for 'readable' value and if the user can read
 * private posts, it will display that for the user that is signed in.
 *
 * @since 2.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $type Optional. Post type to retrieve count. Default 'post'.
 * @param string $perm Optional. 'readable' or empty. Default empty.
 * @return object Number of posts for each status.
 */
function wp_count_posts( $type = 'post', $perm = '' ) {
        global $wpdb;

        if ( ! post_type_exists( $type ) )
                return new stdClass;

        $cache_key = _count_posts_cache_key( $type, $perm );

        $counts = wp_cache_get( $cache_key, 'counts' );
        if ( false !== $counts ) {
                /** This filter is documented in wp-includes/post.php */
                return apply_filters( 'wp_count_posts', $counts, $type, $perm );
        }

        $query = "SELECT post_status, COUNT( * ) AS num_posts FROM {$wpdb->posts} WHERE post_type = %s";
        if ( 'readable' == $perm && is_user_logged_in() ) {
                $post_type_object = get_post_type_object($type);
                if ( ! current_user_can( $post_type_object->cap->read_private_posts ) ) {
                        $query .= $wpdb->prepare( " AND (post_status != 'private' OR ( post_author = %d AND post_status = 'private' ))",
                                get_current_user_id()
                        );
                }
        }
        $query .= ' GROUP BY post_status';

        $results = (array) $wpdb->get_results( $wpdb->prepare( $query, $type ), ARRAY_A );
        $counts = array_fill_keys( get_post_stati(), 0 );

        foreach ( $results as $row ) {
                $counts[ $row['post_status'] ] = $row['num_posts'];
        }

        $counts = (object) $counts;
        wp_cache_set( $cache_key, $counts, 'counts' );

        /**
         * Modify returned post counts by status for the current post type.
         *
         * @since 3.7.0
         *
         * @param object $counts An object containing the current post_type's post
         *                       counts by status.
         * @param string $type   Post type.
         * @param string $perm   The permission to determine if the posts are 'readable'
         *                       by the current user.
         */
        return apply_filters( 'wp_count_posts', $counts, $type, $perm );
}

/**
 * Count number of attachments for the mime type(s).
 *
 * If you set the optional mime_type parameter, then an array will still be
 * returned, but will only have the item you are looking for. It does not give
 * you the number of attachments that are children of a post. You can get that
 * by counting the number of children that post has.
 *
 * @since 2.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string|array $mime_type Optional. Array or comma-separated list of
 *                                MIME patterns. Default empty.
 * @return object An object containing the attachment counts by mime type.
 */
function wp_count_attachments( $mime_type = '' ) {
        global $wpdb;

        $and = wp_post_mime_type_where( $mime_type );
        $count = $wpdb->get_results( "SELECT post_mime_type, COUNT( * ) AS num_posts FROM $wpdb->posts WHERE post_type = 'attachment' AND post_status != 'trash' $and GROUP BY post_mime_type", ARRAY_A );

        $counts = array();
        foreach ( (array) $count as $row ) {
                $counts[ $row['post_mime_type'] ] = $row['num_posts'];
        }
        $counts['trash'] = $wpdb->get_var( "SELECT COUNT( * ) FROM $wpdb->posts WHERE post_type = 'attachment' AND post_status = 'trash' $and");

        /**
         * Modify returned attachment counts by mime type.
         *
         * @since 3.7.0
         *
         * @param object $counts    An object containing the attachment counts by
         *                          mime type.
         * @param string $mime_type The mime type pattern used to filter the attachments
         *                          counted.
         */
        return apply_filters( 'wp_count_attachments', (object) $counts, $mime_type );
}

/**
 * Get default post mime types.
 *
 * @since 2.9.0
 *
 * @return array List of post mime types.
 */
function get_post_mime_types() {
        $post_mime_types = array(       //      array( adj, noun )
                'image' => array(__('Images'), __('Manage Images'), _n_noop('Image <span class="count">(%s)</span>', 'Images <span class="count">(%s)</span>')),
                'audio' => array(__('Audio'), __('Manage Audio'), _n_noop('Audio <span class="count">(%s)</span>', 'Audio <span class="count">(%s)</span>')),
                'video' => array(__('Video'), __('Manage Video'), _n_noop('Video <span class="count">(%s)</span>', 'Video <span class="count">(%s)</span>')),
        );

        /**
         * Filter the default list of post mime types.
         *
         * @since 2.5.0
         *
         * @param array $post_mime_types Default list of post mime types.
         */
        return apply_filters( 'post_mime_types', $post_mime_types );
}

/**
 * Check a MIME-Type against a list.
 *
 * If the wildcard_mime_types parameter is a string, it must be comma separated
 * list. If the real_mime_types is a string, it is also comma separated to
 * create the list.
 *
 * @since 2.5.0
 *
 * @param string|array $wildcard_mime_types Mime types, e.g. audio/mpeg or image (same as image/*)
 *                                          or flash (same as *flash*).
 * @param string|array $real_mime_types     Real post mime type values.
 * @return array array(wildcard=>array(real types)).
 */
function wp_match_mime_types( $wildcard_mime_types, $real_mime_types ) {
        $matches = array();
        if ( is_string( $wildcard_mime_types ) ) {
                $wildcard_mime_types = array_map( 'trim', explode( ',', $wildcard_mime_types ) );
        }
        if ( is_string( $real_mime_types ) ) {
                $real_mime_types = array_map( 'trim', explode( ',', $real_mime_types ) );
        }

        $patternses = array();
        $wild = '[-._a-z0-9]*';

        foreach ( (array) $wildcard_mime_types as $type ) {
                $mimes = array_map( 'trim', explode( ',', $type ) );
                foreach ( $mimes as $mime ) {
                        $regex = str_replace( '__wildcard__', $wild, preg_quote( str_replace( '*', '__wildcard__', $mime ) ) );
                        $patternses[][$type] = "^$regex$";
                        if ( false === strpos( $mime, '/' ) ) {
                                $patternses[][$type] = "^$regex/";
                                $patternses[][$type] = $regex;
                        }
                }
        }
        asort( $patternses );

        foreach ( $patternses as $patterns ) {
                foreach ( $patterns as $type => $pattern ) {
                        foreach ( (array) $real_mime_types as $real ) {
                                if ( preg_match( "#$pattern#", $real ) && ( empty( $matches[$type] ) || false === array_search( $real, $matches[$type] ) ) ) {
                                        $matches[$type][] = $real;
                                }
                        }
                }
        }
        return $matches;
}

/**
 * Convert MIME types into SQL.
 *
 * @since 2.5.0
 *
 * @param string|array $post_mime_types List of mime types or comma separated string
 *                                      of mime types.
 * @param string       $table_alias     Optional. Specify a table alias, if needed.
 *                                      Default empty.
 * @return string The SQL AND clause for mime searching.
 */
function wp_post_mime_type_where( $post_mime_types, $table_alias = '' ) {
        $where = '';
        $wildcards = array('', '%', '%/%');
        if ( is_string($post_mime_types) )
                $post_mime_types = array_map('trim', explode(',', $post_mime_types));

        $wheres = array();

        foreach ( (array) $post_mime_types as $mime_type ) {
                $mime_type = preg_replace('/\s/', '', $mime_type);
                $slashpos = strpos($mime_type, '/');
                if ( false !== $slashpos ) {
                        $mime_group = preg_replace('/[^-*.a-zA-Z0-9]/', '', substr($mime_type, 0, $slashpos));
                        $mime_subgroup = preg_replace('/[^-*.+a-zA-Z0-9]/', '', substr($mime_type, $slashpos + 1));
                        if ( empty($mime_subgroup) )
                                $mime_subgroup = '*';
                        else
                                $mime_subgroup = str_replace('/', '', $mime_subgroup);
                        $mime_pattern = "$mime_group/$mime_subgroup";
                } else {
                        $mime_pattern = preg_replace('/[^-*.a-zA-Z0-9]/', '', $mime_type);
                        if ( false === strpos($mime_pattern, '*') )
                                $mime_pattern .= '/*';
                }

                $mime_pattern = preg_replace('/\*+/', '%', $mime_pattern);

                if ( in_array( $mime_type, $wildcards ) )
                        return '';

                if ( false !== strpos($mime_pattern, '%') )
                        $wheres[] = empty($table_alias) ? "post_mime_type LIKE '$mime_pattern'" : "$table_alias.post_mime_type LIKE '$mime_pattern'";
                else
                        $wheres[] = empty($table_alias) ? "post_mime_type = '$mime_pattern'" : "$table_alias.post_mime_type = '$mime_pattern'";
        }
        if ( !empty($wheres) )
                $where = ' AND (' . join(' OR ', $wheres) . ') ';
        return $where;
}

/**
 * Trash or delete a post or page.
 *
 * When the post and page is permanently deleted, everything that is tied to
 * it is deleted also. This includes comments, post meta fields, and terms
 * associated with the post.
 *
 * The post or page is moved to trash instead of permanently deleted unless
 * trash is disabled, item is already in the trash, or $force_delete is true.
 *
 * @since 1.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 * @see wp_delete_attachment()
 * @see wp_trash_post()
 *
 * @param int  $postid       Optional. Post ID. Default 0.
 * @param bool $force_delete Optional. Whether to bypass trash and force deletion.
 *                           Default false.
 * @return array|false|WP_Post False on failure.
 */
function wp_delete_post( $postid = 0, $force_delete = false ) {
        global $wpdb;

        if ( !$post = $wpdb->get_row($wpdb->prepare("SELECT * FROM $wpdb->posts WHERE ID = %d", $postid)) )
                return $post;

        if ( !$force_delete && ( $post->post_type == 'post' || $post->post_type == 'page') && get_post_status( $postid ) != 'trash' && EMPTY_TRASH_DAYS )
                return wp_trash_post( $postid );

        if ( $post->post_type == 'attachment' )
                return wp_delete_attachment( $postid, $force_delete );

        /**
         * Filter whether a post deletion should take place.
         *
         * @since 4.4.0
         *
         * @param bool    $delete       Whether to go forward with deletion.
         * @param WP_Post $post         Post object.
         * @param bool    $force_delete Whether to bypass the trash.
         */
        $check = apply_filters( 'pre_delete_post', null, $post, $force_delete );
        if ( null !== $check ) {
                return $check;
        }

        /**
         * Fires before a post is deleted, at the start of wp_delete_post().
         *
         * @since 3.2.0
         *
         * @see wp_delete_post()
         *
         * @param int $postid Post ID.
         */
        do_action( 'before_delete_post', $postid );

        delete_post_meta($postid,'_wp_trash_meta_status');
        delete_post_meta($postid,'_wp_trash_meta_time');

        wp_delete_object_term_relationships($postid, get_object_taxonomies($post->post_type));

        $parent_data = array( 'post_parent' => $post->post_parent );
        $parent_where = array( 'post_parent' => $postid );

        if ( is_post_type_hierarchical( $post->post_type ) ) {
                // Point children of this page to its parent, also clean the cache of affected children.
                $children_query = $wpdb->prepare( "SELECT * FROM $wpdb->posts WHERE post_parent = %d AND post_type = %s", $postid, $post->post_type );
                $children = $wpdb->get_results( $children_query );
                if ( $children ) {
                        $wpdb->update( $wpdb->posts, $parent_data, $parent_where + array( 'post_type' => $post->post_type ) );
                }
        }

        // Do raw query. wp_get_post_revisions() is filtered.
        $revision_ids = $wpdb->get_col( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE post_parent = %d AND post_type = 'revision'", $postid ) );
        // Use wp_delete_post (via wp_delete_post_revision) again. Ensures any meta/misplaced data gets cleaned up.
        foreach ( $revision_ids as $revision_id )
                wp_delete_post_revision( $revision_id );

        // Point all attachments to this post up one level.
        $wpdb->update( $wpdb->posts, $parent_data, $parent_where + array( 'post_type' => 'attachment' ) );

        wp_defer_comment_counting( true );

        $comment_ids = $wpdb->get_col( $wpdb->prepare( "SELECT comment_ID FROM $wpdb->comments WHERE comment_post_ID = %d", $postid ));
        foreach ( $comment_ids as $comment_id ) {
                wp_delete_comment( $comment_id, true );
        }

        wp_defer_comment_counting( false );

        $post_meta_ids = $wpdb->get_col( $wpdb->prepare( "SELECT meta_id FROM $wpdb->postmeta WHERE post_id = %d ", $postid ));
        foreach ( $post_meta_ids as $mid )
                delete_metadata_by_mid( 'post', $mid );

        /**
         * Fires immediately before a post is deleted from the database.
         *
         * @since 1.2.0
         *
         * @param int $postid Post ID.
         */
        do_action( 'delete_post', $postid );
        $result = $wpdb->delete( $wpdb->posts, array( 'ID' => $postid ) );
        if ( ! $result ) {
                return false;
        }

        /**
         * Fires immediately after a post is deleted from the database.
         *
         * @since 2.2.0
         *
         * @param int $postid Post ID.
         */
        do_action( 'deleted_post', $postid );

        clean_post_cache( $post );

        if ( is_post_type_hierarchical( $post->post_type ) && $children ) {
                foreach ( $children as $child )
                        clean_post_cache( $child );
        }

        wp_clear_scheduled_hook('publish_future_post', array( $postid ) );

        /**
         * Fires after a post is deleted, at the conclusion of wp_delete_post().
         *
         * @since 3.2.0
         *
         * @see wp_delete_post()
         *
         * @param int $postid Post ID.
         */
        do_action( 'after_delete_post', $postid );

        return $post;
}

/**
 * Reset the page_on_front, show_on_front, and page_for_post settings when
 * a linked page is deleted or trashed.
 *
 * Also ensures the post is no longer sticky.
 *
 * @since 3.7.0
 * @access private
 *
 * @param int $post_id Post ID.
 */
function _reset_front_page_settings_for_post( $post_id ) {
        $post = get_post( $post_id );
        if ( 'page' == $post->post_type ) {
                /*
                 * If the page is defined in option page_on_front or post_for_posts,
                 * adjust the corresponding options.
                 */
                if ( get_option( 'page_on_front' ) == $post->ID ) {
                        update_option( 'show_on_front', 'posts' );
                        update_option( 'page_on_front', 0 );
                }
                if ( get_option( 'page_for_posts' ) == $post->ID ) {
                        delete_option( 'page_for_posts', 0 );
                }
        }
        unstick_post( $post->ID );
}

/**
 * Move a post or page to the Trash
 *
 * If trash is disabled, the post or page is permanently deleted.
 *
 * @since 2.9.0
 *
 * @see wp_delete_post()
 *
 * @param int $post_id Optional. Post ID. Default is ID of the global $post
 *                     if EMPTY_TRASH_DAYS equals true.
 * @return false|array|WP_Post|null Post data array, otherwise false.
 */
function wp_trash_post( $post_id = 0 ) {
        if ( !EMPTY_TRASH_DAYS )
                return wp_delete_post($post_id, true);

        if ( !$post = get_post($post_id, ARRAY_A) )
                return $post;

        if ( $post['post_status'] == 'trash' )
                return false;

        /**
         * Fires before a post is sent to the trash.
         *
         * @since 3.3.0
         *
         * @param int $post_id Post ID.
         */
        do_action( 'wp_trash_post', $post_id );

        add_post_meta($post_id,'_wp_trash_meta_status', $post['post_status']);
        add_post_meta($post_id,'_wp_trash_meta_time', time());

        $post['post_status'] = 'trash';
        wp_insert_post( wp_slash( $post ) );

        wp_trash_post_comments($post_id);

        /**
         * Fires after a post is sent to the trash.
         *
         * @since 2.9.0
         *
         * @param int $post_id Post ID.
         */
        do_action( 'trashed_post', $post_id );

        return $post;
}

/**
 * Restore a post or page from the Trash.
 *
 * @since 2.9.0
 *
 * @param int $post_id Optional. Post ID. Default is ID of the global $post.
 * @return WP_Post|false WP_Post object. False on failure.
 */
function wp_untrash_post( $post_id = 0 ) {
        if ( !$post = get_post($post_id, ARRAY_A) )
                return $post;

        if ( $post['post_status'] != 'trash' )
                return false;

        /**
         * Fires before a post is restored from the trash.
         *
         * @since 2.9.0
         *
         * @param int $post_id Post ID.
         */
        do_action( 'untrash_post', $post_id );

        $post_status = get_post_meta($post_id, '_wp_trash_meta_status', true);

        $post['post_status'] = $post_status;

        delete_post_meta($post_id, '_wp_trash_meta_status');
        delete_post_meta($post_id, '_wp_trash_meta_time');

        wp_insert_post( wp_slash( $post ) );

        wp_untrash_post_comments($post_id);

        /**
         * Fires after a post is restored from the trash.
         *
         * @since 2.9.0
         *
         * @param int $post_id Post ID.
         */
        do_action( 'untrashed_post', $post_id );

        return $post;
}

/**
 * Moves comments for a post to the trash.
 *
 * @since 2.9.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int|WP_Post|null $post Optional. Post ID or post object. Defaults to global $post.
 * @return mixed|void False on failure.
 */
function wp_trash_post_comments( $post = null ) {
        global $wpdb;

        $post = get_post($post);
        if ( empty($post) )
                return;

        $post_id = $post->ID;

        /**
         * Fires before comments are sent to the trash.
         *
         * @since 2.9.0
         *
         * @param int $post_id Post ID.
         */
        do_action( 'trash_post_comments', $post_id );

        $comments = $wpdb->get_results( $wpdb->prepare("SELECT comment_ID, comment_approved FROM $wpdb->comments WHERE comment_post_ID = %d", $post_id) );
        if ( empty($comments) )
                return;

        // Cache current status for each comment.
        $statuses = array();
        foreach ( $comments as $comment )
                $statuses[$comment->comment_ID] = $comment->comment_approved;
        add_post_meta($post_id, '_wp_trash_meta_comments_status', $statuses);

        // Set status for all comments to post-trashed.
        $result = $wpdb->update($wpdb->comments, array('comment_approved' => 'post-trashed'), array('comment_post_ID' => $post_id));

        clean_comment_cache( array_keys($statuses) );

        /**
         * Fires after comments are sent to the trash.
         *
         * @since 2.9.0
         *
         * @param int   $post_id  Post ID.
         * @param array $statuses Array of comment statuses.
         */
        do_action( 'trashed_post_comments', $post_id, $statuses );

        return $result;
}

/**
 * Restore comments for a post from the trash.
 *
 * @since 2.9.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int|WP_Post|null $post Optional. Post ID or post object. Defaults to global $post.
 * @return true|void
 */
function wp_untrash_post_comments( $post = null ) {
        global $wpdb;

        $post = get_post($post);
        if ( empty($post) )
                return;

        $post_id = $post->ID;

        $statuses = get_post_meta($post_id, '_wp_trash_meta_comments_status', true);

        if ( empty($statuses) )
                return true;

        /**
         * Fires before comments are restored for a post from the trash.
         *
         * @since 2.9.0
         *
         * @param int $post_id Post ID.
         */
        do_action( 'untrash_post_comments', $post_id );

        // Restore each comment to its original status.
        $group_by_status = array();
        foreach ( $statuses as $comment_id => $comment_status )
                $group_by_status[$comment_status][] = $comment_id;

        foreach ( $group_by_status as $status => $comments ) {
                // Sanity check. This shouldn't happen.
                if ( 'post-trashed' == $status ) {
                        $status = '0';
                }
                $comments_in = implode( ', ', array_map( 'intval', $comments ) );
                $wpdb->query( $wpdb->prepare( "UPDATE $wpdb->comments SET comment_approved = %s WHERE comment_ID IN ($comments_in)", $status ) );
        }

        clean_comment_cache( array_keys($statuses) );

        delete_post_meta($post_id, '_wp_trash_meta_comments_status');

        /**
         * Fires after comments are restored for a post from the trash.
         *
         * @since 2.9.0
         *
         * @param int $post_id Post ID.
         */
        do_action( 'untrashed_post_comments', $post_id );
}

/**
 * Retrieve the list of categories for a post.
 *
 * Compatibility layer for themes and plugins. Also an easy layer of abstraction
 * away from the complexity of the taxonomy layer.
 *
 * @since 2.1.0
 *
 * @see wp_get_object_terms()
 *
 * @param int   $post_id Optional. The Post ID. Does not default to the ID of the
 *                       global $post. Default 0.
 * @param array $args    Optional. Category arguments. Default empty.
 * @return array List of categories.
 */
function wp_get_post_categories( $post_id = 0, $args = array() ) {
        $post_id = (int) $post_id;

        $defaults = array('fields' => 'ids');
        $args = wp_parse_args( $args, $defaults );

        $cats = wp_get_object_terms($post_id, 'category', $args);
        return $cats;
}

/**
 * Retrieve the tags for a post.
 *
 * There is only one default for this function, called 'fields' and by default
 * is set to 'all'. There are other defaults that can be overridden in
 * {@link wp_get_object_terms()}.
 *
 * @since 2.3.0
 *
 * @param int   $post_id Optional. The Post ID. Does not default to the ID of the
 *                       global $post. Default 0.
 * @param array $args Optional. Overwrite the defaults
 * @return array List of post tags.
 */
function wp_get_post_tags( $post_id = 0, $args = array() ) {
        return wp_get_post_terms( $post_id, 'post_tag', $args);
}

/**
 * Retrieve the terms for a post.
 *
 * There is only one default for this function, called 'fields' and by default
 * is set to 'all'. There are other defaults that can be overridden in
 * {@link wp_get_object_terms()}.
 *
 * @since 2.8.0
 *
 * @param int    $post_id  Optional. The Post ID. Does not default to the ID of the
 *                         global $post. Default 0.
 * @param string $taxonomy Optional. The taxonomy for which to retrieve terms. Default 'post_tag'.
 * @param array  $args     Optional. {@link wp_get_object_terms()} arguments. Default empty array.
 * @return array|WP_Error  List of post terms or empty array if no terms were found. WP_Error object
 *                         if `$taxonomy` doesn't exist.
 */
function wp_get_post_terms( $post_id = 0, $taxonomy = 'post_tag', $args = array() ) {
        $post_id = (int) $post_id;

        $defaults = array('fields' => 'all');
        $args = wp_parse_args( $args, $defaults );

        $tags = wp_get_object_terms($post_id, $taxonomy, $args);

        return $tags;
}

/**
 * Retrieve a number of recent posts.
 *
 * @since 1.0.0
 *
 * @see get_posts()
 *
 * @param array  $args       Optional. Arguments to retrieve posts. Default empty array.
 * @param string $output     Optional. Type of output. Accepts ARRAY_A or ''. Default ARRAY_A.
 * @return array|false Associative array if $output equals ARRAY_A, array or false if no results.
 */
function wp_get_recent_posts( $args = array(), $output = ARRAY_A ) {

        if ( is_numeric( $args ) ) {
                _deprecated_argument( __FUNCTION__, '3.1', __( 'Passing an integer number of posts is deprecated. Pass an array of arguments instead.' ) );
                $args = array( 'numberposts' => absint( $args ) );
        }

        // Set default arguments.
        $defaults = array(
                'numberposts' => 10, 'offset' => 0,
                'category' => 0, 'orderby' => 'post_date',
                'order' => 'DESC', 'include' => '',
                'exclude' => '', 'meta_key' => '',
                'meta_value' =>'', 'post_type' => 'post', 'post_status' => 'draft, publish, future, pending, private',
                'suppress_filters' => true
        );

        $r = wp_parse_args( $args, $defaults );

        $results = get_posts( $r );

        // Backward compatibility. Prior to 3.1 expected posts to be returned in array.
        if ( ARRAY_A == $output ){
                foreach ( $results as $key => $result ) {
                        $results[$key] = get_object_vars( $result );
                }
                return $results ? $results : array();
        }

        return $results ? $results : false;

}

/**
 * Insert or update a post.
 *
 * If the $postarr parameter has 'ID' set to a value, then post will be updated.
 *
 * You can set the post date manually, by setting the values for 'post_date'
 * and 'post_date_gmt' keys. You can close the comments or open the comments by
 * setting the value for 'comment_status' key.
 *
 * @since 1.0.0
 * @since 4.2.0 Support was added for encoding emoji in the post title, content, and excerpt.
 * @since 4.4.0 A 'meta_input' array can now be passed to `$postarr` to add post meta data.
 *
 * @see sanitize_post()
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param array $postarr {
 *     An array of elements that make up a post to update or insert.
 *
 *     @type int    $ID                    The post ID. If equal to something other than 0,
 *                                         the post with that ID will be updated. Default 0.
 *     @type int    $post_author           The ID of the user who added the post. Default is
 *                                         the current user ID.
 *     @type string $post_date             The date of the post. Default is the current time.
 *     @type string $post_date_gmt         The date of the post in the GMT timezone. Default is
 *                                         the value of `$post_date`.
 *     @type mixed  $post_content          The post content. Default empty.
 *     @type string $post_content_filtered The filtered post content. Default empty.
 *     @type string $post_title            The post title. Default empty.
 *     @type string $post_excerpt          The post excerpt. Default empty.
 *     @type string $post_status           The post status. Default 'draft'.
 *     @type string $post_type             The post type. Default 'post'.
 *     @type string $comment_status        Whether the post can accept comments. Accepts 'open' or 'closed'.
 *                                         Default is the value of 'default_comment_status' option.
 *     @type string $ping_status           Whether the post can accept pings. Accepts 'open' or 'closed'.
 *                                         Default is the value of 'default_ping_status' option.
 *     @type string $post_password         The password to access the post. Default empty.
 *     @type string $post_name             The post name. Default is the sanitized post title
 *                                         when creating a new post.
 *     @type string $to_ping               Space or carriage return-separated list of URLs to ping.
 *                                         Default empty.
 *     @type string $pinged                Space or carriage return-separated list of URLs that have
 *                                         been pinged. Default empty.
 *     @type string $post_modified         The date when the post was last modified. Default is
 *                                         the current time.
 *     @type string $post_modified_gmt     The date when the post was last modified in the GMT
 *                                         timezone. Default is the current time.
 *     @type int    $post_parent           Set this for the post it belongs to, if any. Default 0.
 *     @type int    $menu_order            The order the post should be displayed in. Default 0.
 *     @type string $post_mime_type        The mime type of the post. Default empty.
 *     @type string $guid                  Global Unique ID for referencing the post. Default empty.
 *     @type array  $tax_input             Array of taxonomy terms keyed by their taxonomy name. Default empty.
 *     @type array  $meta_input            Array of post meta values keyed by their post meta key. Default empty.
 * }
 * @param bool  $wp_error Optional. Whether to allow return of WP_Error on failure. Default false.
 * @return int|WP_Error The post ID on success. The value 0 or WP_Error on failure.
 */
function wp_insert_post( $postarr, $wp_error = false ) {
        global $wpdb;

        $user_id = get_current_user_id();

        $defaults = array(
                'post_author' => $user_id,
                'post_content' => '',
                'post_content_filtered' => '',
                'post_title' => '',
                'post_excerpt' => '',
                'post_status' => 'draft',
                'post_type' => 'post',
                'comment_status' => '',
                'ping_status' => '',
                'post_password' => '',
                'to_ping' =>  '',
                'pinged' => '',
                'post_parent' => 0,
                'menu_order' => 0,
                'guid' => '',
                'import_id' => 0,
                'context' => '',
        );

        $postarr = wp_parse_args($postarr, $defaults);

        unset( $postarr[ 'filter' ] );

        $postarr = sanitize_post($postarr, 'db');

        // Are we updating or creating?
        $post_ID = 0;
        $update = false;
        $guid = $postarr['guid'];

        if ( ! empty( $postarr['ID'] ) ) {
                $update = true;

                // Get the post ID and GUID.
                $post_ID = $postarr['ID'];
                $post_before = get_post( $post_ID );
                if ( is_null( $post_before ) ) {
                        if ( $wp_error ) {
                                return new WP_Error( 'invalid_post', __( 'Invalid post ID.' ) );
                        }
                        return 0;
                }

                $guid = get_post_field( 'guid', $post_ID );
                $previous_status = get_post_field('post_status', $post_ID );
        } else {
                $previous_status = 'new';
        }

        $post_type = empty( $postarr['post_type'] ) ? 'post' : $postarr['post_type'];

        $post_title = $postarr['post_title'];
        $post_content = $postarr['post_content'];
        $post_excerpt = $postarr['post_excerpt'];
        if ( isset( $postarr['post_name'] ) ) {
                $post_name = $postarr['post_name'];
        } elseif ( $update ) {
                // For an update, don't modify the post_name if it wasn't supplied as an argument.
                $post_name = $post_before->post_name;
        }

        $maybe_empty = 'attachment' !== $post_type
                && ! $post_content && ! $post_title && ! $post_excerpt
                && post_type_supports( $post_type, 'editor' )
                && post_type_supports( $post_type, 'title' )
                && post_type_supports( $post_type, 'excerpt' );

        /**
         * Filter whether the post should be considered "empty".
         *
         * The post is considered "empty" if both:
         * 1. The post type supports the title, editor, and excerpt fields
         * 2. The title, editor, and excerpt fields are all empty
         *
         * Returning a truthy value to the filter will effectively short-circuit
         * the new post being inserted, returning 0. If $wp_error is true, a WP_Error
         * will be returned instead.
         *
         * @since 3.3.0
         *
         * @param bool  $maybe_empty Whether the post should be considered "empty".
         * @param array $postarr     Array of post data.
         */
        if ( apply_filters( 'wp_insert_post_empty_content', $maybe_empty, $postarr ) ) {
                if ( $wp_error ) {
                        return new WP_Error( 'empty_content', __( 'Content, title, and excerpt are empty.' ) );
                } else {
                        return 0;
                }
        }

        $post_status = empty( $postarr['post_status'] ) ? 'draft' : $postarr['post_status'];
        if ( 'attachment' === $post_type && ! in_array( $post_status, array( 'inherit', 'private', 'trash' ) ) ) {
                $post_status = 'inherit';
        }

        if ( ! empty( $postarr['post_category'] ) ) {
                // Filter out empty terms.
                $post_category = array_filter( $postarr['post_category'] );
        }

        // Make sure we set a valid category.
        if ( empty( $post_category ) || 0 == count( $post_category ) || ! is_array( $post_category ) ) {
                // 'post' requires at least one category.
                if ( 'post' == $post_type && 'auto-draft' != $post_status ) {
                        $post_category = array( get_option('default_category') );
                } else {
                        $post_category = array();
                }
        }

        // Don't allow contributors to set the post slug for pending review posts.
        if ( 'pending' == $post_status && !current_user_can( 'publish_posts' ) ) {
                $post_name = '';
        }

        /*
         * Create a valid post name. Drafts and pending posts are allowed to have
         * an empty post name.
         */
        if ( empty($post_name) ) {
                if ( !in_array( $post_status, array( 'draft', 'pending', 'auto-draft' ) ) ) {
                        $post_name = sanitize_title($post_title);
                } else {
                        $post_name = '';
                }
        } else {
                // On updates, we need to check to see if it's using the old, fixed sanitization context.
                $check_name = sanitize_title( $post_name, '', 'old-save' );
                if ( $update && strtolower( urlencode( $post_name ) ) == $check_name && get_post_field( 'post_name', $post_ID ) == $check_name ) {
                        $post_name = $check_name;
                } else { // new post, or slug has changed.
                        $post_name = sanitize_title($post_name);
                }
        }

        /*
         * If the post date is empty (due to having been new or a draft) and status
         * is not 'draft' or 'pending', set date to now.
         */
        if ( empty( $postarr['post_date'] ) || '0000-00-00 00:00:00' == $postarr['post_date'] ) {
                if ( empty( $postarr['post_date_gmt'] ) || '0000-00-00 00:00:00' == $postarr['post_date_gmt'] ) {
                        $post_date = current_time( 'mysql' );
                } else {
                        $post_date = get_date_from_gmt( $postarr['post_date_gmt'] );
                }
        } else {
                $post_date = $postarr['post_date'];
        }

        // Validate the date.
        $mm = substr( $post_date, 5, 2 );
        $jj = substr( $post_date, 8, 2 );
        $aa = substr( $post_date, 0, 4 );
        $valid_date = wp_checkdate( $mm, $jj, $aa, $post_date );
        if ( ! $valid_date ) {
                if ( $wp_error ) {
                        return new WP_Error( 'invalid_date', __( 'Whoops, the provided date is invalid.' ) );
                } else {
                        return 0;
                }
        }

        if ( empty( $postarr['post_date_gmt'] ) || '0000-00-00 00:00:00' == $postarr['post_date_gmt'] ) {
                if ( ! in_array( $post_status, array( 'draft', 'pending', 'auto-draft' ) ) ) {
                        $post_date_gmt = get_gmt_from_date( $post_date );
                } else {
                        $post_date_gmt = '0000-00-00 00:00:00';
                }
        } else {
                $post_date_gmt = $postarr['post_date_gmt'];
        }

        if ( $update || '0000-00-00 00:00:00' == $post_date ) {
                $post_modified     = current_time( 'mysql' );
                $post_modified_gmt = current_time( 'mysql', 1 );
        } else {
                $post_modified     = $post_date;
                $post_modified_gmt = $post_date_gmt;
        }

        if ( 'attachment' !== $post_type ) {
                if ( 'publish' == $post_status ) {
                        $now = gmdate('Y-m-d H:i:59');
                        if ( mysql2date('U', $post_date_gmt, false) > mysql2date('U', $now, false) ) {
                                $post_status = 'future';
                        }
                } elseif ( 'future' == $post_status ) {
                        $now = gmdate('Y-m-d H:i:59');
                        if ( mysql2date('U', $post_date_gmt, false) <= mysql2date('U', $now, false) ) {
                                $post_status = 'publish';
                        }
                }
        }

        // Comment status.
        if ( empty( $postarr['comment_status'] ) ) {
                if ( $update ) {
                        $comment_status = 'closed';
                } else {
                        $comment_status = get_default_comment_status( $post_type );
                }
        } else {
                $comment_status = $postarr['comment_status'];
        }

        // These variables are needed by compact() later.
        $post_content_filtered = $postarr['post_content_filtered'];
        $post_author = isset( $postarr['post_author'] ) ? $postarr['post_author'] : $user_id;
        $ping_status = empty( $postarr['ping_status'] ) ? get_default_comment_status( $post_type, 'pingback' ) : $postarr['ping_status'];
        $to_ping = isset( $postarr['to_ping'] ) ? sanitize_trackback_urls( $postarr['to_ping'] ) : '';
        $pinged = isset( $postarr['pinged'] ) ? $postarr['pinged'] : '';
        $import_id = isset( $postarr['import_id'] ) ? $postarr['import_id'] : 0;

        /*
         * The 'wp_insert_post_parent' filter expects all variables to be present.
         * Previously, these variables would have already been extracted
         */
        if ( isset( $postarr['menu_order'] ) ) {
                $menu_order = (int) $postarr['menu_order'];
        } else {
                $menu_order = 0;
        }

        $post_password = isset( $postarr['post_password'] ) ? $postarr['post_password'] : '';
        if ( 'private' == $post_status ) {
                $post_password = '';
        }

        if ( isset( $postarr['post_parent'] ) ) {
                $post_parent = (int) $postarr['post_parent'];
        } else {
                $post_parent = 0;
        }

        /**
         * Filter the post parent -- used to check for and prevent hierarchy loops.
         *
         * @since 3.1.0
         *
         * @param int   $post_parent Post parent ID.
         * @param int   $post_ID     Post ID.
         * @param array $new_postarr Array of parsed post data.
         * @param array $postarr     Array of sanitized, but otherwise unmodified post data.
         */
        $post_parent = apply_filters( 'wp_insert_post_parent', $post_parent, $post_ID, compact( array_keys( $postarr ) ), $postarr );

        /*
         * If the post is being untrashed and it has a desired slug stored in post meta,
         * reassign it.
         */
        if ( 'trash' === $previous_status && 'trash' !== $post_status ) {
                $desired_post_slug = get_post_meta( $post_ID, '_wp_desired_post_slug', true );
                if ( $desired_post_slug ) {
                        delete_post_meta( $post_ID, '_wp_desired_post_slug' );
                        $post_name = $desired_post_slug;
                }
        }

        // If a trashed post has the desired slug, change it and let this post have it.
        if ( 'trash' !== $post_status && $post_name ) {
                wp_add_trashed_suffix_to_post_name_for_trashed_posts( $post_name, $post_ID );
        }

        // When trashing an existing post, change its slug to allow non-trashed posts to use it.
        if ( 'trash' === $post_status && 'trash' !== $previous_status && 'new' !== $previous_status ) {
                $post_name = wp_add_trashed_suffix_to_post_name_for_post( $post_ID );
        }

        $post_name = wp_unique_post_slug( $post_name, $post_ID, $post_status, $post_type, $post_parent );

        // Don't unslash.
        $post_mime_type = isset( $postarr['post_mime_type'] ) ? $postarr['post_mime_type'] : '';

        // Expected_slashed (everything!).
        $data = compact( 'post_author', 'post_date', 'post_date_gmt', 'post_content', 'post_content_filtered', 'post_title', 'post_excerpt', 'post_status', 'post_type', 'comment_status', 'ping_status', 'post_password', 'post_name', 'to_ping', 'pinged', 'post_modified', 'post_modified_gmt', 'post_parent', 'menu_order', 'post_mime_type', 'guid' );

        $emoji_fields = array( 'post_title', 'post_content', 'post_excerpt' );

        foreach ( $emoji_fields as $emoji_field ) {
                if ( isset( $data[ $emoji_field ] ) ) {
                        $charset = $wpdb->get_col_charset( $wpdb->posts, $emoji_field );
                        if ( 'utf8' === $charset ) {
                                $data[ $emoji_field ] = wp_encode_emoji( $data[ $emoji_field ] );
                        }
                }
        }

        if ( 'attachment' === $post_type ) {
                /**
                 * Filter attachment post data before it is updated in or added to the database.
                 *
                 * @since 3.9.0
                 *
                 * @param array $data    An array of sanitized attachment post data.
                 * @param array $postarr An array of unsanitized attachment post data.
                 */
                $data = apply_filters( 'wp_insert_attachment_data', $data, $postarr );
        } else {
                /**
                 * Filter slashed post data just before it is inserted into the database.
                 *
                 * @since 2.7.0
                 *
                 * @param array $data    An array of slashed post data.
                 * @param array $postarr An array of sanitized, but otherwise unmodified post data.
                 */
                $data = apply_filters( 'wp_insert_post_data', $data, $postarr );
        }
        $data = wp_unslash( $data );
        $where = array( 'ID' => $post_ID );

        if ( $update ) {
                /**
                 * Fires immediately before an existing post is updated in the database.
                 *
                 * @since 2.5.0
                 *
                 * @param int   $post_ID Post ID.
                 * @param array $data    Array of unslashed post data.
                 */
                do_action( 'pre_post_update', $post_ID, $data );
                if ( false === $wpdb->update( $wpdb->posts, $data, $where ) ) {
                        if ( $wp_error ) {
                                return new WP_Error('db_update_error', __('Could not update post in the database'), $wpdb->last_error);
                        } else {
                                return 0;
                        }
                }
        } else {
                // If there is a suggested ID, use it if not already present.
                if ( ! empty( $import_id ) ) {
                        $import_id = (int) $import_id;
                        if ( ! $wpdb->get_var( $wpdb->prepare("SELECT ID FROM $wpdb->posts WHERE ID = %d", $import_id) ) ) {
                                $data['ID'] = $import_id;
                        }
                }
                if ( false === $wpdb->insert( $wpdb->posts, $data ) ) {
                        if ( $wp_error ) {
                                return new WP_Error('db_insert_error', __('Could not insert post into the database'), $wpdb->last_error);
                        } else {
                                return 0;
                        }
                }
                $post_ID = (int) $wpdb->insert_id;

                // Use the newly generated $post_ID.
                $where = array( 'ID' => $post_ID );
        }

        if ( empty( $data['post_name'] ) && ! in_array( $data['post_status'], array( 'draft', 'pending', 'auto-draft' ) ) ) {
                $data['post_name'] = wp_unique_post_slug( sanitize_title( $data['post_title'], $post_ID ), $post_ID, $data['post_status'], $post_type, $post_parent );
                $wpdb->update( $wpdb->posts, array( 'post_name' => $data['post_name'] ), $where );
                clean_post_cache( $post_ID );
        }

        if ( is_object_in_taxonomy( $post_type, 'category' ) ) {
                wp_set_post_categories( $post_ID, $post_category );
        }

        if ( isset( $postarr['tags_input'] ) && is_object_in_taxonomy( $post_type, 'post_tag' ) ) {
                wp_set_post_tags( $post_ID, $postarr['tags_input'] );
        }

        // New-style support for all custom taxonomies.
        if ( ! empty( $postarr['tax_input'] ) ) {
                foreach ( $postarr['tax_input'] as $taxonomy => $tags ) {
                        $taxonomy_obj = get_taxonomy($taxonomy);
                        if ( ! $taxonomy_obj ) {
                                /* translators: %s: taxonomy name */
                                _doing_it_wrong( __FUNCTION__, sprintf( __( 'Invalid taxonomy: %s.' ), $taxonomy ), '4.4.0' );
                                continue;
                        }

                        // array = hierarchical, string = non-hierarchical.
                        if ( is_array( $tags ) ) {
                                $tags = array_filter($tags);
                        }
                        if ( current_user_can( $taxonomy_obj->cap->assign_terms ) ) {
                                wp_set_post_terms( $post_ID, $tags, $taxonomy );
                        }
                }
        }

        if ( ! empty( $postarr['meta_input'] ) ) {
                foreach ( $postarr['meta_input'] as $field => $value ) {
                        update_post_meta( $post_ID, $field, $value );
                }
        }

        $current_guid = get_post_field( 'guid', $post_ID );

        // Set GUID.
        if ( ! $update && '' == $current_guid ) {
                $wpdb->update( $wpdb->posts, array( 'guid' => get_permalink( $post_ID ) ), $where );
        }

        if ( 'attachment' === $postarr['post_type'] ) {
                if ( ! empty( $postarr['file'] ) ) {
                        update_attached_file( $post_ID, $postarr['file'] );
                }

                if ( ! empty( $postarr['context'] ) ) {
                        add_post_meta( $post_ID, '_wp_attachment_context', $postarr['context'], true );
                }
        }

        clean_post_cache( $post_ID );

        $post = get_post( $post_ID );

        if ( ! empty( $postarr['page_template'] ) && 'page' == $data['post_type'] ) {
                $post->page_template = $postarr['page_template'];
                $page_templates = wp_get_theme()->get_page_templates( $post );
                if ( 'default' != $postarr['page_template'] && ! isset( $page_templates[ $postarr['page_template'] ] ) ) {
                        if ( $wp_error ) {
                                return new WP_Error('invalid_page_template', __('The page template is invalid.'));
                        }
                        update_post_meta( $post_ID, '_wp_page_template', 'default' );
                } else {
                        update_post_meta( $post_ID, '_wp_page_template', $postarr['page_template'] );
                }
        }

        if ( 'attachment' !== $postarr['post_type'] ) {
                wp_transition_post_status( $data['post_status'], $previous_status, $post );
        } else {
                if ( $update ) {
                        /**
                         * Fires once an existing attachment has been updated.
                         *
                         * @since 2.0.0
                         *
                         * @param int $post_ID Attachment ID.
                         */
                        do_action( 'edit_attachment', $post_ID );
                        $post_after = get_post( $post_ID );

                        /**
                         * Fires once an existing attachment has been updated.
                         *
                         * @since 4.4.0
                         *
                         * @param int     $post_ID      Post ID.
                         * @param WP_Post $post_after   Post object following the update.
                         * @param WP_Post $post_before  Post object before the update.
                         */
                        do_action( 'attachment_updated', $post_ID, $post_after, $post_before );
                } else {

                        /**
                         * Fires once an attachment has been added.
                         *
                         * @since 2.0.0
                         *
                         * @param int $post_ID Attachment ID.
                         */
                        do_action( 'add_attachment', $post_ID );
                }

                return $post_ID;
        }

        if ( $update ) {
                /**
                 * Fires once an existing post has been updated.
                 *
                 * @since 1.2.0
                 *
                 * @param int     $post_ID Post ID.
                 * @param WP_Post $post    Post object.
                 */
                do_action( 'edit_post', $post_ID, $post );
                $post_after = get_post($post_ID);

                /**
                 * Fires once an existing post has been updated.
                 *
                 * @since 3.0.0
                 *
                 * @param int     $post_ID      Post ID.
                 * @param WP_Post $post_after   Post object following the update.
                 * @param WP_Post $post_before  Post object before the update.
                 */
                do_action( 'post_updated', $post_ID, $post_after, $post_before);
        }

        /**
         * Fires once a post has been saved.
         *
         * The dynamic portion of the hook name, `$post->post_type`, refers to
         * the post type slug.
         *
         * @since 3.7.0
         *
         * @param int     $post_ID Post ID.
         * @param WP_Post $post    Post object.
         * @param bool    $update  Whether this is an existing post being updated or not.
         */
        do_action( "save_post_{$post->post_type}", $post_ID, $post, $update );

        /**
         * Fires once a post has been saved.
         *
         * @since 1.5.0
         *
         * @param int     $post_ID Post ID.
         * @param WP_Post $post    Post object.
         * @param bool    $update  Whether this is an existing post being updated or not.
         */
        do_action( 'save_post', $post_ID, $post, $update );

        /**
         * Fires once a post has been saved.
         *
         * @since 2.0.0
         *
         * @param int     $post_ID Post ID.
         * @param WP_Post $post    Post object.
         * @param bool    $update  Whether this is an existing post being updated or not.
         */
        do_action( 'wp_insert_post', $post_ID, $post, $update );

        return $post_ID;
}

/**
 * Update a post with new post data.
 *
 * The date does not have to be set for drafts. You can set the date and it will
 * not be overridden.
 *
 * @since 1.0.0
 *
 * @param array|object $postarr  Optional. Post data. Arrays are expected to be escaped,
 *                               objects are not. Default array.
 * @param bool         $wp_error Optional. Allow return of WP_Error on failure. Default false.
 * @return int|WP_Error The value 0 or WP_Error on failure. The post ID on success.
 */
function wp_update_post( $postarr = array(), $wp_error = false ) {
        if ( is_object($postarr) ) {
                // Non-escaped post was passed.
                $postarr = get_object_vars($postarr);
                $postarr = wp_slash($postarr);
        }

        // First, get all of the original fields.
        $post = get_post($postarr['ID'], ARRAY_A);

        if ( is_null( $post ) ) {
                if ( $wp_error )
                        return new WP_Error( 'invalid_post', __( 'Invalid post ID.' ) );
                return 0;
        }

        // Escape data pulled from DB.
        $post = wp_slash($post);

        // Passed post category list overwrites existing category list if not empty.
        if ( isset($postarr['post_category']) && is_array($postarr['post_category'])
                         && 0 != count($postarr['post_category']) )
                $post_cats = $postarr['post_category'];
        else
                $post_cats = $post['post_category'];

        // Drafts shouldn't be assigned a date unless explicitly done so by the user.
        if ( isset( $post['post_status'] ) && in_array($post['post_status'], array('draft', 'pending', 'auto-draft')) && empty($postarr['edit_date']) &&
                         ('0000-00-00 00:00:00' == $post['post_date_gmt']) )
                $clear_date = true;
        else
                $clear_date = false;

        // Merge old and new fields with new fields overwriting old ones.
        $postarr = array_merge($post, $postarr);
        $postarr['post_category'] = $post_cats;
        if ( $clear_date ) {
                $postarr['post_date'] = current_time('mysql');
                $postarr['post_date_gmt'] = '';
        }

        if ($postarr['post_type'] == 'attachment')
                return wp_insert_attachment($postarr);

        return wp_insert_post( $postarr, $wp_error );
}

/**
 * Publish a post by transitioning the post status.
 *
 * @since 2.1.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int|WP_Post $post Post ID or post object.
 */
function wp_publish_post( $post ) {
        global $wpdb;

        if ( ! $post = get_post( $post ) )
                return;

        if ( 'publish' == $post->post_status )
                return;

        $wpdb->update( $wpdb->posts, array( 'post_status' => 'publish' ), array( 'ID' => $post->ID ) );

        clean_post_cache( $post->ID );

        $old_status = $post->post_status;
        $post->post_status = 'publish';
        wp_transition_post_status( 'publish', $old_status, $post );

        /** This action is documented in wp-includes/post.php */
        do_action( 'edit_post', $post->ID, $post );

        /** This action is documented in wp-includes/post.php */
        do_action( "save_post_{$post->post_type}", $post->ID, $post, true );

        /** This action is documented in wp-includes/post.php */
        do_action( 'save_post', $post->ID, $post, true );

        /** This action is documented in wp-includes/post.php */
        do_action( 'wp_insert_post', $post->ID, $post, true );
}

/**
 * Publish future post and make sure post ID has future post status.
 *
 * Invoked by cron 'publish_future_post' event. This safeguard prevents cron
 * from publishing drafts, etc.
 *
 * @since 2.5.0
 *
 * @param int|WP_Post $post_id Post ID or post object.
 */
function check_and_publish_future_post( $post_id ) {
        $post = get_post($post_id);

        if ( empty($post) )
                return;

        if ( 'future' != $post->post_status )
                return;

        $time = strtotime( $post->post_date_gmt . ' GMT' );

        // Uh oh, someone jumped the gun!
        if ( $time > time() ) {
                wp_clear_scheduled_hook( 'publish_future_post', array( $post_id ) ); // clear anything else in the system
                wp_schedule_single_event( $time, 'publish_future_post', array( $post_id ) );
                return;
        }

        // wp_publish_post(_ returns no meaningful value.
        wp_publish_post( $post_id );
}

/**
 * Computes a unique slug for the post, when given the desired slug and some post details.
 *
 * @since 2.8.0
 *
 * @global wpdb       $wpdb WordPress database abstraction object.
 * @global WP_Rewrite $wp_rewrite
 *
 * @param string $slug        The desired slug (post_name).
 * @param int    $post_ID     Post ID.
 * @param string $post_status No uniqueness checks are made if the post is still draft or pending.
 * @param string $post_type   Post type.
 * @param int    $post_parent Post parent ID.
 * @return string Unique slug for the post, based on $post_name (with a -1, -2, etc. suffix)
 */
function wp_unique_post_slug( $slug, $post_ID, $post_status, $post_type, $post_parent ) {
        if ( in_array( $post_status, array( 'draft', 'pending', 'auto-draft' ) ) || ( 'inherit' == $post_status && 'revision' == $post_type ) )
                return $slug;

        global $wpdb, $wp_rewrite;

        $original_slug = $slug;

        $feeds = $wp_rewrite->feeds;
        if ( ! is_array( $feeds ) )
                $feeds = array();

        if ( 'attachment' == $post_type ) {
                // Attachment slugs must be unique across all types.
                $check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND ID != %d LIMIT 1";
                $post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_ID ) );

                /**
                 * Filter whether the post slug would make a bad attachment slug.
                 *
                 * @since 3.1.0
                 *
                 * @param bool   $bad_slug Whether the slug would be bad as an attachment slug.
                 * @param string $slug     The post slug.
                 */
                if ( $post_name_check || in_array( $slug, $feeds ) || 'embed' === $slug || apply_filters( 'wp_unique_post_slug_is_bad_attachment_slug', false, $slug ) ) {
                        $suffix = 2;
                        do {
                                $alt_post_name = _truncate_post_slug( $slug, 200 - ( strlen( $suffix ) + 1 ) ) . "-$suffix";
                                $post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $alt_post_name, $post_ID ) );
                                $suffix++;
                        } while ( $post_name_check );
                        $slug = $alt_post_name;
                }
        } elseif ( is_post_type_hierarchical( $post_type ) ) {
                if ( 'nav_menu_item' == $post_type )
                        return $slug;

                /*
                 * Page slugs must be unique within their own trees. Pages are in a separate
                 * namespace than posts so page slugs are allowed to overlap post slugs.
                 */
                $check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN ( %s, 'attachment' ) AND ID != %d AND post_parent = %d LIMIT 1";
                $post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_type, $post_ID, $post_parent ) );

                /**
                 * Filter whether the post slug would make a bad hierarchical post slug.
                 *
                 * @since 3.1.0
                 *
                 * @param bool   $bad_slug    Whether the post slug would be bad in a hierarchical post context.
                 * @param string $slug        The post slug.
                 * @param string $post_type   Post type.
                 * @param int    $post_parent Post parent ID.
                 */
                if ( $post_name_check || in_array( $slug, $feeds ) || 'embed' === $slug || preg_match( "@^($wp_rewrite->pagination_base)?\d+$@", $slug )  || apply_filters( 'wp_unique_post_slug_is_bad_hierarchical_slug', false, $slug, $post_type, $post_parent ) ) {
                        $suffix = 2;
                        do {
                                $alt_post_name = _truncate_post_slug( $slug, 200 - ( strlen( $suffix ) + 1 ) ) . "-$suffix";
                                $post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $alt_post_name, $post_type, $post_ID, $post_parent ) );
                                $suffix++;
                        } while ( $post_name_check );
                        $slug = $alt_post_name;
                }
        } else {
                // Post slugs must be unique across all posts.
                $check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type = %s AND ID != %d LIMIT 1";
                $post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_type, $post_ID ) );

                // Prevent new post slugs that could result in URLs that conflict with date archives.
                $post = get_post( $post_ID );
                $conflicts_with_date_archive = false;
                if ( 'post' === $post_type && ( ! $post || $post->post_name !== $slug ) && preg_match( '/^[0-9]+$/', $slug ) && $slug_num = intval( $slug ) ) {
                        $permastructs   = array_values( array_filter( explode( '/', get_option( 'permalink_structure' ) ) ) );
                        $postname_index = array_search( '%postname%', $permastructs );

                        /*
                         * Potential date clashes are as follows:
                         *
                         * - Any integer in the first permastruct position could be a year.
                         * - An integer between 1 and 12 that follows 'year' conflicts with 'monthnum'.
                         * - An integer between 1 and 31 that follows 'monthnum' conflicts with 'day'.
                         */
                        if ( 0 === $postname_index ||
                                ( $postname_index && '%year%' === $permastructs[ $postname_index - 1 ] && 13 > $slug_num ) ||
                                ( $postname_index && '%monthnum%' === $permastructs[ $postname_index - 1 ] && 32 > $slug_num )
                        ) {
                                $conflicts_with_date_archive = true;
                        }
                }

                /**
                 * Filter whether the post slug would be bad as a flat slug.
                 *
                 * @since 3.1.0
                 *
                 * @param bool   $bad_slug  Whether the post slug would be bad as a flat slug.
                 * @param string $slug      The post slug.
                 * @param string $post_type Post type.
                 */
                if ( $post_name_check || in_array( $slug, $feeds ) || 'embed' === $slug || $conflicts_with_date_archive || apply_filters( 'wp_unique_post_slug_is_bad_flat_slug', false, $slug, $post_type ) ) {
                        $suffix = 2;
                        do {
                                $alt_post_name = _truncate_post_slug( $slug, 200 - ( strlen( $suffix ) + 1 ) ) . "-$suffix";
                                $post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $alt_post_name, $post_type, $post_ID ) );
                                $suffix++;
                        } while ( $post_name_check );
                        $slug = $alt_post_name;
                }
        }

        /**
         * Filter the unique post slug.
         *
         * @since 3.3.0
         *
         * @param string $slug          The post slug.
         * @param int    $post_ID       Post ID.
         * @param string $post_status   The post status.
         * @param string $post_type     Post type.
         * @param int    $post_parent   Post parent ID
         * @param string $original_slug The original post slug.
         */
        return apply_filters( 'wp_unique_post_slug', $slug, $post_ID, $post_status, $post_type, $post_parent, $original_slug );
}

/**
 * Truncate a post slug.
 *
 * @since 3.6.0
 * @access private
 *
 * @see utf8_uri_encode()
 *
 * @param string $slug   The slug to truncate.
 * @param int    $length Optional. Max length of the slug. Default 200 (characters).
 * @return string The truncated slug.
 */
function _truncate_post_slug( $slug, $length = 200 ) {
        if ( strlen( $slug ) > $length ) {
                $decoded_slug = urldecode( $slug );
                if ( $decoded_slug === $slug )
                        $slug = substr( $slug, 0, $length );
                else
                        $slug = utf8_uri_encode( $decoded_slug, $length );
        }

        return rtrim( $slug, '-' );
}

/**
 * Add tags to a post.
 *
 * @see wp_set_post_tags()
 *
 * @since 2.3.0
 *
 * @param int          $post_id Optional. The Post ID. Does not default to the ID of the global $post.
 * @param string|array $tags    Optional. An array of tags to set for the post, or a string of tags
 *                              separated by commas. Default empty.
 * @return array|false|WP_Error Array of affected term IDs. WP_Error or false on failure.
 */
function wp_add_post_tags( $post_id = 0, $tags = '' ) {
        return wp_set_post_tags($post_id, $tags, true);
}

/**
 * Set the tags for a post.
 *
 * @since 2.3.0
 *
 * @see wp_set_object_terms()
 *
 * @param int          $post_id Optional. The Post ID. Does not default to the ID of the global $post.
 * @param string|array $tags    Optional. An array of tags to set for the post, or a string of tags
 *                              separated by commas. Default empty.
 * @param bool         $append  Optional. If true, don't delete existing tags, just add on. If false,
 *                              replace the tags with the new tags. Default false.
 * @return array|false|WP_Error Array of term taxonomy IDs of affected terms. WP_Error or false on failure.
 */
function wp_set_post_tags( $post_id = 0, $tags = '', $append = false ) {
        return wp_set_post_terms( $post_id, $tags, 'post_tag', $append);
}

/**
 * Set the terms for a post.
 *
 * @since 2.8.0
 *
 * @see wp_set_object_terms()
 *
 * @param int          $post_id  Optional. The Post ID. Does not default to the ID of the global $post.
 * @param string|array $tags     Optional. An array of terms to set for the post, or a string of terms
 *                               separated by commas. Default empty.
 * @param string       $taxonomy Optional. Taxonomy name. Default 'post_tag'.
 * @param bool         $append   Optional. If true, don't delete existing terms, just add on. If false,
 *                               replace the terms with the new terms. Default false.
 * @return array|false|WP_Error Array of term taxonomy IDs of affected terms. WP_Error or false on failure.
 */
function wp_set_post_terms( $post_id = 0, $tags = '', $taxonomy = 'post_tag', $append = false ) {
        $post_id = (int) $post_id;

        if ( !$post_id )
                return false;

        if ( empty($tags) )
                $tags = array();

        if ( ! is_array( $tags ) ) {
                $comma = _x( ',', 'tag delimiter' );
                if ( ',' !== $comma )
                        $tags = str_replace( $comma, ',', $tags );
                $tags = explode( ',', trim( $tags, " \n\t\r\0\x0B," ) );
        }

        /*
         * Hierarchical taxonomies must always pass IDs rather than names so that
         * children with the same names but different parents aren't confused.
         */
        if ( is_taxonomy_hierarchical( $taxonomy ) ) {
                $tags = array_unique( array_map( 'intval', $tags ) );
        }

        return wp_set_object_terms( $post_id, $tags, $taxonomy, $append );
}

/**
 * Set categories for a post.
 *
 * If the post categories parameter is not set, then the default category is
 * going used.
 *
 * @since 2.1.0
 *
 * @param int       $post_ID         Optional. The Post ID. Does not default to the ID
 *                                   of the global $post. Default 0.
 * @param array|int $post_categories Optional. List of categories or ID of category.
 *                                   Default empty array.
 * @param bool      $append         If true, don't delete existing categories, just add on.
 *                                  If false, replace the categories with the new categories.
 * @return array|false|WP_Error Array of term taxonomy IDs of affected categories. WP_Error or false on failure.
 */
function wp_set_post_categories( $post_ID = 0, $post_categories = array(), $append = false ) {
        $post_ID = (int) $post_ID;
        $post_type = get_post_type( $post_ID );
        $post_status = get_post_status( $post_ID );
        // If $post_categories isn't already an array, make it one:
        $post_categories = (array) $post_categories;
        if ( empty( $post_categories ) ) {
                if ( 'post' == $post_type && 'auto-draft' != $post_status ) {
                        $post_categories = array( get_option('default_category') );
                        $append = false;
                } else {
                        $post_categories = array();
                }
        } elseif ( 1 == count( $post_categories ) && '' == reset( $post_categories ) ) {
                return true;
        }

        return wp_set_post_terms( $post_ID, $post_categories, 'category', $append );
}

/**
 * Fires actions related to the transitioning of a post's status.
 *
 * When a post is saved, the post status is "transitioned" from one status to another,
 * though this does not always mean the status has actually changed before and after
 * the save. This function fires a number of action hooks related to that transition:
 * the generic 'transition_post_status' action, as well as the dynamic hooks
 * `"{$old_status}_to_{$new_status}"` and `"{$new_status}_{$post->post_type}"`. Note
 * that the function does not transition the post object in the database.
 *
 * For instance: When publishing a post for the first time, the post status may transition
 * from 'draft' – or some other status – to 'publish'. However, if a post is already
 * published and is simply being updated, the "old" and "new" statuses may both be 'publish'
 * before and after the transition.
 *
 * @since 2.3.0
 *
 * @param string  $new_status Transition to this post status.
 * @param string  $old_status Previous post status.
 * @param WP_Post $post Post data.
 */
function wp_transition_post_status( $new_status, $old_status, $post ) {
        /**
         * Fires when a post is transitioned from one status to another.
         *
         * @since 2.3.0
         *
         * @param string  $new_status New post status.
         * @param string  $old_status Old post status.
         * @param WP_Post $post       Post object.
         */
        do_action( 'transition_post_status', $new_status, $old_status, $post );

        /**
         * Fires when a post is transitioned from one status to another.
         *
         * The dynamic portions of the hook name, `$new_status` and `$old status`,
         * refer to the old and new post statuses, respectively.
         *
         * @since 2.3.0
         *
         * @param WP_Post $post Post object.
         */
        do_action( "{$old_status}_to_{$new_status}", $post );

        /**
         * Fires when a post is transitioned from one status to another.
         *
         * The dynamic portions of the hook name, `$new_status` and `$post->post_type`,
         * refer to the new post status and post type, respectively.
         *
         * Please note: When this action is hooked using a particular post status (like
         * 'publish', as `publish_{$post->post_type}`), it will fire both when a post is
         * first transitioned to that status from something else, as well as upon
         * subsequent post updates (old and new status are both the same).
         *
         * Therefore, if you are looking to only fire a callback when a post is first
         * transitioned to a status, use the {@see 'transition_post_status'} hook instead.
         *
         * @since 2.3.0
         *
         * @param int     $post_id Post ID.
         * @param WP_Post $post    Post object.
         */
        do_action( "{$new_status}_{$post->post_type}", $post->ID, $post );
}

//
// Comment, trackback, and pingback functions.
//

/**
 * Add a URL to those already pinged.
 *
 * @since 1.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int    $post_id Post ID.
 * @param string $uri     Ping URI.
 * @return int|false How many rows were updated.
 */
function add_ping( $post_id, $uri ) {
        global $wpdb;
        $pung = $wpdb->get_var( $wpdb->prepare( "SELECT pinged FROM $wpdb->posts WHERE ID = %d", $post_id ));
        $pung = trim($pung);
        $pung = preg_split('/\s/', $pung);
        $pung[] = $uri;
        $new = implode("\n", $pung);

        /**
         * Filter the new ping URL to add for the given post.
         *
         * @since 2.0.0
         *
         * @param string $new New ping URL to add.
         */
        $new = apply_filters( 'add_ping', $new );

        // expected_slashed ($new).
        $new = wp_unslash($new);
        return $wpdb->update( $wpdb->posts, array( 'pinged' => $new ), array( 'ID' => $post_id ) );
}

/**
 * Retrieve enclosures already enclosed for a post.
 *
 * @since 1.5.0
 *
 * @param int $post_id Post ID.
 * @return array List of enclosures.
 */
function get_enclosed( $post_id ) {
        $custom_fields = get_post_custom( $post_id );
        $pung = array();
        if ( !is_array( $custom_fields ) )
                return $pung;

        foreach ( $custom_fields as $key => $val ) {
                if ( 'enclosure' != $key || !is_array( $val ) )
                        continue;
                foreach ( $val as $enc ) {
                        $enclosure = explode( "\n", $enc );
                        $pung[] = trim( $enclosure[ 0 ] );
                }
        }

        /**
         * Filter the list of enclosures already enclosed for the given post.
         *
         * @since 2.0.0
         *
         * @param array $pung    Array of enclosures for the given post.
         * @param int   $post_id Post ID.
         */
        return apply_filters( 'get_enclosed', $pung, $post_id );
}

/**
 * Retrieve URLs already pinged for a post.
 *
 * @since 1.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int $post_id Post ID.
 * @return array
 */
function get_pung( $post_id ) {
        global $wpdb;
        $pung = $wpdb->get_var( $wpdb->prepare( "SELECT pinged FROM $wpdb->posts WHERE ID = %d", $post_id ));
        $pung = trim($pung);
        $pung = preg_split('/\s/', $pung);

        /**
         * Filter the list of already-pinged URLs for the given post.
         *
         * @since 2.0.0
         *
         * @param array $pung Array of URLs already pinged for the given post.
         */
        return apply_filters( 'get_pung', $pung );
}

/**
 * Retrieve URLs that need to be pinged.
 *
 * @since 1.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int $post_id Post ID
 * @return array
 */
function get_to_ping( $post_id ) {
        global $wpdb;
        $to_ping = $wpdb->get_var( $wpdb->prepare( "SELECT to_ping FROM $wpdb->posts WHERE ID = %d", $post_id ));
        $to_ping = sanitize_trackback_urls( $to_ping );
        $to_ping = preg_split('/\s/', $to_ping, -1, PREG_SPLIT_NO_EMPTY);

        /**
         * Filter the list of URLs yet to ping for the given post.
         *
         * @since 2.0.0
         *
         * @param array $to_ping List of URLs yet to ping.
         */
        return apply_filters( 'get_to_ping', $to_ping );
}

/**
 * Do trackbacks for a list of URLs.
 *
 * @since 1.0.0
 *
 * @param string $tb_list Comma separated list of URLs.
 * @param int    $post_id Post ID.
 */
function trackback_url_list( $tb_list, $post_id ) {
        if ( ! empty( $tb_list ) ) {
                // Get post data.
                $postdata = get_post( $post_id, ARRAY_A );

                // Form an excerpt.
                $excerpt = strip_tags( $postdata['post_excerpt'] ? $postdata['post_excerpt'] : $postdata['post_content'] );

                if ( strlen( $excerpt ) > 255 ) {
                        $excerpt = substr( $excerpt, 0, 252 ) . '&hellip;';
                }

                $trackback_urls = explode( ',', $tb_list );
                foreach ( (array) $trackback_urls as $tb_url ) {
                        $tb_url = trim( $tb_url );
                        trackback( $tb_url, wp_unslash( $postdata['post_title'] ), $excerpt, $post_id );
                }
        }
}

//
// Page functions
//

/**
 * Get a list of page IDs.
 *
 * @since 2.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @return array List of page IDs.
 */
function get_all_page_ids() {
        global $wpdb;

        $page_ids = wp_cache_get('all_page_ids', 'posts');
        if ( ! is_array( $page_ids ) ) {
                $page_ids = $wpdb->get_col("SELECT ID FROM $wpdb->posts WHERE post_type = 'page'");
                wp_cache_add('all_page_ids', $page_ids, 'posts');
        }

        return $page_ids;
}

/**
 * Retrieves page data given a page ID or page object.
 *
 * Use get_post() instead of get_page().
 *
 * @since 1.5.1
 * @deprecated 3.5.0 Use get_post()
 *
 * @param mixed  $page   Page object or page ID. Passed by reference.
 * @param string $output Optional. What to output. Accepts OBJECT, ARRAY_A, or ARRAY_N.
 *                       Default OBJECT.
 * @param string $filter Optional. How the return value should be filtered. Accepts 'raw',
 *                       'edit', 'db', 'display'. Default 'raw'.
 * @return WP_Post|array|null WP_Post on success or null on failure.
 */
function get_page( $page, $output = OBJECT, $filter = 'raw') {
        return get_post( $page, $output, $filter );
}

/**
 * Retrieves a page given its path.
 *
 * @since 2.1.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string       $page_path Page path.
 * @param string       $output    Optional. Output type. Accepts OBJECT, ARRAY_N, or ARRAY_A.
 *                                Default OBJECT.
 * @param string|array $post_type Optional. Post type or array of post types. Default 'page'.
 * @return WP_Post|array|void WP_Post on success.
 */
function get_page_by_path( $page_path, $output = OBJECT, $post_type = 'page' ) {
        global $wpdb;

        $page_path = rawurlencode(urldecode($page_path));
        $page_path = str_replace('%2F', '/', $page_path);
        $page_path = str_replace('%20', ' ', $page_path);
        $parts = explode( '/', trim( $page_path, '/' ) );
        $parts = esc_sql( $parts );
        $parts = array_map( 'sanitize_title_for_query', $parts );

        $in_string = "'" . implode( "','", $parts ) . "'";

        if ( is_array( $post_type ) ) {
                $post_types = $post_type;
        } else {
                $post_types = array( $post_type, 'attachment' );
        }

        $post_types = esc_sql( $post_types );
        $post_type_in_string = "'" . implode( "','", $post_types ) . "'";
        $sql = "
                SELECT ID, post_name, post_parent, post_type
                FROM $wpdb->posts
                WHERE post_name IN ($in_string)
                AND post_type IN ($post_type_in_string)
        ";

        $pages = $wpdb->get_results( $sql, OBJECT_K );

        $revparts = array_reverse( $parts );

        $foundid = 0;
        foreach ( (array) $pages as $page ) {
                if ( $page->post_name == $revparts[0] ) {
                        $count = 0;
                        $p = $page;

                        /*
                         * Loop through the given path parts from right to left,
                         * ensuring each matches the post ancestry.
                         */
                        while ( $p->post_parent != 0 && isset( $pages[ $p->post_parent ] ) ) {
                                $count++;
                                $parent = $pages[ $p->post_parent ];
                                if ( ! isset( $revparts[ $count ] ) || $parent->post_name != $revparts[ $count ] )
                                        break;
                                $p = $parent;
                        }

                        if ( $p->post_parent == 0 && $count+1 == count( $revparts ) && $p->post_name == $revparts[ $count ] ) {
                                $foundid = $page->ID;
                                if ( $page->post_type == $post_type )
                                        break;
                        }
                }
        }

        if ( $foundid ) {
                return get_post( $foundid, $output );
        }
}

/**
 * Retrieve a page given its title.
 *
 * @since 2.1.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string       $page_title Page title
 * @param string       $output     Optional. Output type. OBJECT, ARRAY_N, or ARRAY_A.
 *                                 Default OBJECT.
 * @param string|array $post_type  Optional. Post type or array of post types. Default 'page'.
 * @return WP_Post|array|void WP_Post on success or null on failure
 */
function get_page_by_title( $page_title, $output = OBJECT, $post_type = 'page' ) {
        global $wpdb;

        if ( is_array( $post_type ) ) {
                $post_type = esc_sql( $post_type );
                $post_type_in_string = "'" . implode( "','", $post_type ) . "'";
                $sql = $wpdb->prepare( "
                        SELECT ID
                        FROM $wpdb->posts
                        WHERE post_title = %s
                        AND post_type IN ($post_type_in_string)
                ", $page_title );
        } else {
                $sql = $wpdb->prepare( "
                        SELECT ID
                        FROM $wpdb->posts
                        WHERE post_title = %s
                        AND post_type = %s
                ", $page_title, $post_type );
        }

        $page = $wpdb->get_var( $sql );

        if ( $page ) {
                return get_post( $page, $output );
        }
}

/**
 * Identify descendants of a given page ID in a list of page objects.
 *
 * Descendants are identified from the `$pages` array passed to the function. No database queries are performed.
 *
 * @since 1.5.1
 *
 * @param int   $page_id Page ID.
 * @param array $pages   List of page objects from which descendants should be identified.
 * @return array List of page children.
 */
function get_page_children( $page_id, $pages ) {
        // Build a hash of ID -> children.
        $children = array();
        foreach ( (array) $pages as $page ) {
                $children[ intval( $page->post_parent ) ][] = $page;
        }

        $page_list = array();

        // Start the search by looking at immediate children.
        if ( isset( $children[ $page_id ] ) ) {
                // Always start at the end of the stack in order to preserve original `$pages` order.
                $to_look = array_reverse( $children[ $page_id ] );

                while ( $to_look ) {
                        $p = array_pop( $to_look );
                        $page_list[] = $p;
                        if ( isset( $children[ $p->ID ] ) ) {
                                foreach ( array_reverse( $children[ $p->ID ] ) as $child ) {
                                        // Append to the `$to_look` stack to descend the tree.
                                        $to_look[] = $child;
                                }
                        }
                }
        }

        return $page_list;
}

/**
 * Order the pages with children under parents in a flat list.
 *
 * It uses auxiliary structure to hold parent-children relationships and
 * runs in O(N) complexity
 *
 * @since 2.0.0
 *
 * @param array $pages   Posts array, passed by reference.
 * @param int   $page_id Optional. Parent page ID. Default 0.
 * @return array A list arranged by hierarchy. Children immediately follow their parents.
 */
function get_page_hierarchy( &$pages, $page_id = 0 ) {
        if ( empty( $pages ) ) {
                return array();
        }

        $children = array();
        foreach ( (array) $pages as $p ) {
                $parent_id = intval( $p->post_parent );
                $children[ $parent_id ][] = $p;
        }

        $result = array();
        _page_traverse_name( $page_id, $children, $result );

        return $result;
}

/**
 * Traverse and return all the nested children post names of a root page.
 *
 * $children contains parent-children relations
 *
 * @since 2.9.0
 *
 * @see _page_traverse_name()
 *
 * @param int   $page_id   Page ID.
 * @param array $children  Parent-children relations, passed by reference.
 * @param array $result    Result, passed by reference.
 */
function _page_traverse_name( $page_id, &$children, &$result ){
        if ( isset( $children[ $page_id ] ) ){
                foreach ( (array)$children[ $page_id ] as $child ) {
                        $result[ $child->ID ] = $child->post_name;
                        _page_traverse_name( $child->ID, $children, $result );
                }
        }
}

/**
 * Build the URI path for a page.
 *
 * Sub pages will be in the "directory" under the parent page post name.
 *
 * @since 1.5.0
 *
 * @param WP_Post|object|int $page Page object or page ID.
 * @return string|false Page URI, false on error.
 */
function get_page_uri( $page ) {
        if ( ! $page instanceof WP_Post ) {
                $page = get_post( $page );
        }

        if ( ! $page )
                return false;

        $uri = $page->post_name;

        foreach ( $page->ancestors as $parent ) {
                $parent = get_post( $parent );
                if ( $parent ) {
                        $uri = $parent->post_name . '/' . $uri;
                }
        }

        /**
         * Filter the URI for a page.
         *
         * @since 4.4.0
         *
         * @param string  $uri  Page URI.
         * @param WP_Post $page Page object.
         */
        return apply_filters( 'get_page_uri', $uri, $page );
}

/**
 * Retrieve a list of pages.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @since 1.5.0
 *
 * @param array|string $args {
 *     Optional. Array or string of arguments to retrieve pages.
 *
 *     @type int          $child_of     Page ID to return child and grandchild pages of. Note: The value
 *                                      of `$hierarchical` has no bearing on whether `$child_of` returns
 *                                      hierarchical results. Default 0, or no restriction.
 *     @type string       $sort_order   How to sort retrieved pages. Accepts 'ASC', 'DESC'. Default 'ASC'.
 *     @type string       $sort_column  What columns to sort pages by, comma-separated. Accepts 'post_author',
 *                                      'post_date', 'post_title', 'post_name', 'post_modified', 'menu_order',
 *                                      'post_modified_gmt', 'post_parent', 'ID', 'rand', 'comment_count'.
 *                                      'post_' can be omitted for any values that start with it.
 *                                      Default 'post_title'.
 *     @type bool         $hierarchical Whether to return pages hierarchically. If false in conjunction with
 *                                      `$child_of` also being false, both arguments will be disregarded.
 *                                      Default true.
 *     @type array        $exclude      Array of page IDs to exclude. Default empty array.
 *     @type array        $include      Array of page IDs to include. Cannot be used with `$child_of`,
 *                                      `$parent`, `$exclude`, `$meta_key`, `$meta_value`, or `$hierarchical`.
 *                                      Default empty array.
 *     @type string       $meta_key     Only include pages with this meta key. Default empty.
 *     @type string       $meta_value   Only include pages with this meta value. Requires `$meta_key`.
 *                                      Default empty.
 *     @type string       $authors      A comma-separated list of author IDs. Default empty.
 *     @type int          $parent       Page ID to return direct children of. Default -1, or no restriction.
 *     @type string|array $exclude_tree Comma-separated string or array of page IDs to exclude.
 *                                      Default empty array.
 *     @type int          $number       The number of pages to return. Default 0, or all pages.
 *     @type int          $offset       The number of pages to skip before returning. Requires `$number`.
 *                                      Default 0.
 *     @type string       $post_type    The post type to query. Default 'page'.
 *     @type string       $post_status  A comma-separated list of post status types to include.
 *                                      Default 'publish'.
 * }
 * @return array|false List of pages matching defaults or `$args`.
 */
function get_pages( $args = array() ) {
        global $wpdb;

        $defaults = array(
                'child_of' => 0, 'sort_order' => 'ASC',
                'sort_column' => 'post_title', 'hierarchical' => 1,
                'exclude' => array(), 'include' => array(),
                'meta_key' => '', 'meta_value' => '',
                'authors' => '', 'parent' => -1, 'exclude_tree' => array(),
                'number' => '', 'offset' => 0,
                'post_type' => 'page', 'post_status' => 'publish',
        );

        $r = wp_parse_args( $args, $defaults );

        $number = (int) $r['number'];
        $offset = (int) $r['offset'];
        $child_of = (int) $r['child_of'];
        $hierarchical = $r['hierarchical'];
        $exclude = $r['exclude'];
        $meta_key = $r['meta_key'];
        $meta_value = $r['meta_value'];
        $parent = $r['parent'];
        $post_status = $r['post_status'];

        // Make sure the post type is hierarchical.
        $hierarchical_post_types = get_post_types( array( 'hierarchical' => true ) );
        if ( ! in_array( $r['post_type'], $hierarchical_post_types ) ) {
                return false;
        }

        if ( $parent > 0 && ! $child_of ) {
                $hierarchical = false;
        }

        // Make sure we have a valid post status.
        if ( ! is_array( $post_status ) ) {
                $post_status = explode( ',', $post_status );
        }
        if ( array_diff( $post_status, get_post_stati() ) ) {
                return false;
        }

        // $args can be whatever, only use the args defined in defaults to compute the key.
        $key = md5( serialize( wp_array_slice_assoc( $r, array_keys( $defaults ) ) ) );
        $last_changed = wp_cache_get( 'last_changed', 'posts' );
        if ( ! $last_changed ) {
                $last_changed = microtime();
                wp_cache_set( 'last_changed', $last_changed, 'posts' );
        }

        $cache_key = "get_pages:$key:$last_changed";
        if ( $cache = wp_cache_get( $cache_key, 'posts' ) ) {
                // Convert to WP_Post instances.
                $pages = array_map( 'get_post', $cache );
                /** This filter is documented in wp-includes/post.php */
                $pages = apply_filters( 'get_pages', $pages, $r );
                return $pages;
        }

        $inclusions = '';
        if ( ! empty( $r['include'] ) ) {
                $child_of = 0; //ignore child_of, parent, exclude, meta_key, and meta_value params if using include
                $parent = -1;
                $exclude = '';
                $meta_key = '';
                $meta_value = '';
                $hierarchical = false;
                $incpages = wp_parse_id_list( $r['include'] );
                if ( ! empty( $incpages ) ) {
                        $inclusions = ' AND ID IN (' . implode( ',', $incpages ) .  ')';
                }
        }

        $exclusions = '';
        if ( ! empty( $exclude ) ) {
                $expages = wp_parse_id_list( $exclude );
                if ( ! empty( $expages ) ) {
                        $exclusions = ' AND ID NOT IN (' . implode( ',', $expages ) .  ')';
                }
        }

        $author_query = '';
        if ( ! empty( $r['authors'] ) ) {
                $post_authors = preg_split( '/[\s,]+/', $r['authors'] );

                if ( ! empty( $post_authors ) ) {
                        foreach ( $post_authors as $post_author ) {
                                //Do we have an author id or an author login?
                                if ( 0 == intval($post_author) ) {
                                        $post_author = get_user_by('login', $post_author);
                                        if ( empty( $post_author ) ) {
                                                continue;
                                        }
                                        if ( empty( $post_author->ID ) ) {
                                                continue;
                                        }
                                        $post_author = $post_author->ID;
                                }

                                if ( '' == $author_query ) {
                                        $author_query = $wpdb->prepare(' post_author = %d ', $post_author);
                                } else {
                                        $author_query .= $wpdb->prepare(' OR post_author = %d ', $post_author);
                                }
                        }
                        if ( '' != $author_query ) {
                                $author_query = " AND ($author_query)";
                        }
                }
        }

        $join = '';
        $where = "$exclusions $inclusions ";
        if ( '' !== $meta_key || '' !== $meta_value ) {
                $join = " LEFT JOIN $wpdb->postmeta ON ( $wpdb->posts.ID = $wpdb->postmeta.post_id )";

                // meta_key and meta_value might be slashed
                $meta_key = wp_unslash($meta_key);
                $meta_value = wp_unslash($meta_value);
                if ( '' !== $meta_key ) {
                        $where .= $wpdb->prepare(" AND $wpdb->postmeta.meta_key = %s", $meta_key);
                }
                if ( '' !== $meta_value ) {
                        $where .= $wpdb->prepare(" AND $wpdb->postmeta.meta_value = %s", $meta_value);
                }

        }

        if ( is_array( $parent ) ) {
                $post_parent__in = implode( ',', array_map( 'absint', (array) $parent ) );
                if ( ! empty( $post_parent__in ) ) {
                        $where .= " AND post_parent IN ($post_parent__in)";
                }
        } elseif ( $parent >= 0 ) {
                $where .= $wpdb->prepare(' AND post_parent = %d ', $parent);
        }

        if ( 1 == count( $post_status ) ) {
                $where_post_type = $wpdb->prepare( "post_type = %s AND post_status = %s", $r['post_type'], reset( $post_status ) );
        } else {
                $post_status = implode( "', '", $post_status );
                $where_post_type = $wpdb->prepare( "post_type = %s AND post_status IN ('$post_status')", $r['post_type'] );
        }

        $orderby_array = array();
        $allowed_keys = array( 'author', 'post_author', 'date', 'post_date', 'title', 'post_title', 'name', 'post_name', 'modified',
                'post_modified', 'modified_gmt', 'post_modified_gmt', 'menu_order', 'parent', 'post_parent',
                'ID', 'rand', 'comment_count' );

        foreach ( explode( ',', $r['sort_column'] ) as $orderby ) {
                $orderby = trim( $orderby );
                if ( ! in_array( $orderby, $allowed_keys ) ) {
                        continue;
                }

                switch ( $orderby ) {
                        case 'menu_order':
                                break;
                        case 'ID':
                                $orderby = "$wpdb->posts.ID";
                                break;
                        case 'rand':
                                $orderby = 'RAND()';
                                break;
                        case 'comment_count':
                                $orderby = "$wpdb->posts.comment_count";
                                break;
                        default:
                                if ( 0 === strpos( $orderby, 'post_' ) ) {
                                        $orderby = "$wpdb->posts." . $orderby;
                                } else {
                                        $orderby = "$wpdb->posts.post_" . $orderby;
                                }
                }

                $orderby_array[] = $orderby;

        }
        $sort_column = ! empty( $orderby_array ) ? implode( ',', $orderby_array ) : "$wpdb->posts.post_title";

        $sort_order = strtoupper( $r['sort_order'] );
        if ( '' !== $sort_order && ! in_array( $sort_order, array( 'ASC', 'DESC' ) ) ) {
                $sort_order = 'ASC';
        }

        $query = "SELECT * FROM $wpdb->posts $join WHERE ($where_post_type) $where ";
        $query .= $author_query;
        $query .= " ORDER BY " . $sort_column . " " . $sort_order ;

        if ( ! empty( $number ) ) {
                $query .= ' LIMIT ' . $offset . ',' . $number;
        }

        $pages = $wpdb->get_results($query);

        if ( empty($pages) ) {
                /** This filter is documented in wp-includes/post.php */
                $pages = apply_filters( 'get_pages', array(), $r );
                return $pages;
        }

        // Sanitize before caching so it'll only get done once.
        $num_pages = count($pages);
        for ($i = 0; $i < $num_pages; $i++) {
                $pages[$i] = sanitize_post($pages[$i], 'raw');
        }

        // Update cache.
        update_post_cache( $pages );

        if ( $child_of || $hierarchical ) {
                $pages = get_page_children($child_of, $pages);
        }

        if ( ! empty( $r['exclude_tree'] ) ) {
                $exclude = wp_parse_id_list( $r['exclude_tree'] );
                foreach ( $exclude as $id ) {
                        $children = get_page_children( $id, $pages );
                        foreach ( $children as $child ) {
                                $exclude[] = $child->ID;
                        }
                }

                $num_pages = count( $pages );
                for ( $i = 0; $i < $num_pages; $i++ ) {
                        if ( in_array( $pages[$i]->ID, $exclude ) ) {
                                unset( $pages[$i] );
                        }
                }
        }

        $page_structure = array();
        foreach ( $pages as $page ) {
                $page_structure[] = $page->ID;
        }

        wp_cache_set( $cache_key, $page_structure, 'posts' );

        // Convert to WP_Post instances
        $pages = array_map( 'get_post', $pages );

        /**
         * Filter the retrieved list of pages.
         *
         * @since 2.1.0
         *
         * @param array $pages List of pages to retrieve.
         * @param array $r     Array of get_pages() arguments.
         */
        return apply_filters( 'get_pages', $pages, $r );
}

//
// Attachment functions
//

/**
 * Check if the attachment URI is local one and is really an attachment.
 *
 * @since 2.0.0
 *
 * @param string $url URL to check
 * @return bool True on success, false on failure.
 */
function is_local_attachment($url) {
        if (strpos($url, home_url()) === false)
                return false;
        if (strpos($url, home_url('/?attachment_id=')) !== false)
                return true;
        if ( $id = url_to_postid($url) ) {
                $post = get_post($id);
                if ( 'attachment' == $post->post_type )
                        return true;
        }
        return false;
}

/**
 * Insert an attachment.
 *
 * If you set the 'ID' in the $args parameter, it will mean that you are
 * updating and attempt to update the attachment. You can also set the
 * attachment name or title by setting the key 'post_name' or 'post_title'.
 *
 * You can set the dates for the attachment manually by setting the 'post_date'
 * and 'post_date_gmt' keys' values.
 *
 * By default, the comments will use the default settings for whether the
 * comments are allowed. You can close them manually or keep them open by
 * setting the value for the 'comment_status' key.
 *
 * @since 2.0.0
 *
 * @see wp_insert_post()
 *
 * @param string|array $args   Arguments for inserting an attachment.
 * @param string       $file   Optional. Filename.
 * @param int          $parent Optional. Parent post ID.
 * @return int Attachment ID.
 */
function wp_insert_attachment( $args, $file = false, $parent = 0 ) {
        $defaults = array(
                'file'        => $file,
                'post_parent' => 0
        );

        $data = wp_parse_args( $args, $defaults );

        if ( ! empty( $parent ) ) {
                $data['post_parent'] = $parent;
        }

        $data['post_type'] = 'attachment';

        return wp_insert_post( $data );
}

/**
 * Trash or delete an attachment.
 *
 * When an attachment is permanently deleted, the file will also be removed.
 * Deletion removes all post meta fields, taxonomy, comments, etc. associated
 * with the attachment (except the main post).
 *
 * The attachment is moved to the trash instead of permanently deleted unless trash
 * for media is disabled, item is already in the trash, or $force_delete is true.
 *
 * @since 2.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int  $post_id      Attachment ID.
 * @param bool $force_delete Optional. Whether to bypass trash and force deletion.
 *                           Default false.
 * @return mixed False on failure. Post data on success.
 */
function wp_delete_attachment( $post_id, $force_delete = false ) {
        global $wpdb;

        if ( !$post = $wpdb->get_row( $wpdb->prepare("SELECT * FROM $wpdb->posts WHERE ID = %d", $post_id) ) )
                return $post;

        if ( 'attachment' != $post->post_type )
                return false;

        if ( !$force_delete && EMPTY_TRASH_DAYS && MEDIA_TRASH && 'trash' != $post->post_status )
                return wp_trash_post( $post_id );

        delete_post_meta($post_id, '_wp_trash_meta_status');
        delete_post_meta($post_id, '_wp_trash_meta_time');

        $meta = wp_get_attachment_metadata( $post_id );
        $backup_sizes = get_post_meta( $post->ID, '_wp_attachment_backup_sizes', true );
        $file = get_attached_file( $post_id );

        if ( is_multisite() )
                delete_transient( 'dirsize_cache' );

        /**
         * Fires before an attachment is deleted, at the start of wp_delete_attachment().
         *
         * @since 2.0.0
         *
         * @param int $post_id Attachment ID.
         */
        do_action( 'delete_attachment', $post_id );

        wp_delete_object_term_relationships($post_id, array('category', 'post_tag'));
        wp_delete_object_term_relationships($post_id, get_object_taxonomies($post->post_type));

        // Delete all for any posts.
        delete_metadata( 'post', null, '_thumbnail_id', $post_id, true );

        wp_defer_comment_counting( true );

        $comment_ids = $wpdb->get_col( $wpdb->prepare( "SELECT comment_ID FROM $wpdb->comments WHERE comment_post_ID = %d", $post_id ));
        foreach ( $comment_ids as $comment_id ) {
                wp_delete_comment( $comment_id, true );
        }

        wp_defer_comment_counting( false );

        $post_meta_ids = $wpdb->get_col( $wpdb->prepare( "SELECT meta_id FROM $wpdb->postmeta WHERE post_id = %d ", $post_id ));
        foreach ( $post_meta_ids as $mid )
                delete_metadata_by_mid( 'post', $mid );

        /** This action is documented in wp-includes/post.php */
        do_action( 'delete_post', $post_id );
        $result = $wpdb->delete( $wpdb->posts, array( 'ID' => $post_id ) );
        if ( ! $result ) {
                return false;
        }
        /** This action is documented in wp-includes/post.php */
        do_action( 'deleted_post', $post_id );

        $uploadpath = wp_get_upload_dir();

        if ( ! empty($meta['thumb']) ) {
                // Don't delete the thumb if another attachment uses it.
                if (! $wpdb->get_row( $wpdb->prepare( "SELECT meta_id FROM $wpdb->postmeta WHERE meta_key = '_wp_attachment_metadata' AND meta_value LIKE %s AND post_id <> %d", '%' . $wpdb->esc_like( $meta['thumb'] ) . '%', $post_id)) ) {
                        $thumbfile = str_replace(basename($file), $meta['thumb'], $file);
                        /** This filter is documented in wp-includes/functions.php */
                        $thumbfile = apply_filters( 'wp_delete_file', $thumbfile );
                        @ unlink( path_join($uploadpath['basedir'], $thumbfile) );
                }
        }

        // Remove intermediate and backup images if there are any.
        if ( isset( $meta['sizes'] ) && is_array( $meta['sizes'] ) ) {
                foreach ( $meta['sizes'] as $size => $sizeinfo ) {
                        $intermediate_file = str_replace( basename( $file ), $sizeinfo['file'], $file );
                        /** This filter is documented in wp-includes/functions.php */
                        $intermediate_file = apply_filters( 'wp_delete_file', $intermediate_file );
                        @ unlink( path_join( $uploadpath['basedir'], $intermediate_file ) );
                }
        }

        if ( is_array($backup_sizes) ) {
                foreach ( $backup_sizes as $size ) {
                        $del_file = path_join( dirname($meta['file']), $size['file'] );
                        /** This filter is documented in wp-includes/functions.php */
                        $del_file = apply_filters( 'wp_delete_file', $del_file );
                        @ unlink( path_join($uploadpath['basedir'], $del_file) );
                }
        }

        wp_delete_file( $file );

        clean_post_cache( $post );

        return $post;
}

/**
 * Retrieve attachment meta field for attachment ID.
 *
 * @since 2.1.0
 *
 * @param int  $post_id    Attachment ID. Default 0.
 * @param bool $unfiltered Optional. If true, filters are not run. Default false.
 * @return mixed Attachment meta field. False on failure.
 */
function wp_get_attachment_metadata( $post_id = 0, $unfiltered = false ) {
        $post_id = (int) $post_id;
        if ( !$post = get_post( $post_id ) )
                return false;

        $data = get_post_meta( $post->ID, '_wp_attachment_metadata', true );

        if ( $unfiltered )
                return $data;

        /**
         * Filter the attachment meta data.
         *
         * @since 2.1.0
         *
         * @param array|bool $data    Array of meta data for the given attachment, or false
         *                            if the object does not exist.
         * @param int        $post_id Attachment ID.
         */
        return apply_filters( 'wp_get_attachment_metadata', $data, $post->ID );
}

/**
 * Update metadata for an attachment.
 *
 * @since 2.1.0
 *
 * @param int   $post_id Attachment ID.
 * @param array $data    Attachment data.
 * @return int|bool False if $post is invalid.
 */
function wp_update_attachment_metadata( $post_id, $data ) {
        $post_id = (int) $post_id;
        if ( !$post = get_post( $post_id ) )
                return false;

        /**
         * Filter the updated attachment meta data.
         *
         * @since 2.1.0
         *
         * @param array $data    Array of updated attachment meta data.
         * @param int   $post_id Attachment ID.
         */
        if ( $data = apply_filters( 'wp_update_attachment_metadata', $data, $post->ID ) )
                return update_post_meta( $post->ID, '_wp_attachment_metadata', $data );
        else
                return delete_post_meta( $post->ID, '_wp_attachment_metadata' );
}

/**
 * Retrieve the URL for an attachment.
 *
 * @since 2.1.0
 *
 * @global string $pagenow
 *
 * @param int $post_id Optional. Attachment ID. Default 0.
 * @return string|false Attachment URL, otherwise false.
 */
function wp_get_attachment_url( $post_id = 0 ) {
        $post_id = (int) $post_id;
        if ( !$post = get_post( $post_id ) )
                return false;

        if ( 'attachment' != $post->post_type )
                return false;

        $url = '';
        // Get attached file.
        if ( $file = get_post_meta( $post->ID, '_wp_attached_file', true ) ) {
                // Get upload directory.
                if ( ( $uploads = wp_get_upload_dir() ) && false === $uploads['error'] ) {
                        // Check that the upload base exists in the file location.
                        if ( 0 === strpos( $file, $uploads['basedir'] ) ) {
                                // Replace file location with url location.
                                $url = str_replace($uploads['basedir'], $uploads['baseurl'], $file);
                        } elseif ( false !== strpos($file, 'wp-content/uploads') ) {
                                // Get the directory name relative to the basedir (back compat for pre-2.7 uploads)
                                $url = trailingslashit( $uploads['baseurl'] . '/' . _wp_get_attachment_relative_path( $file ) ) . basename( $file );
                        } else {
                                // It's a newly-uploaded file, therefore $file is relative to the basedir.
                                $url = $uploads['baseurl'] . "/$file";
                        }
                }
        }

        /*
         * If any of the above options failed, Fallback on the GUID as used pre-2.7,
         * not recommended to rely upon this.
         */
        if ( empty($url) ) {
                $url = get_the_guid( $post->ID );
        }

        // On SSL front end, URLs should be HTTPS.
        if ( is_ssl() && ! is_admin() && 'wp-login.php' !== $GLOBALS['pagenow'] ) {
                $url = set_url_scheme( $url );
        }

        /**
         * Filter the attachment URL.
         *
         * @since 2.1.0
         *
         * @param string $url     URL for the given attachment.
         * @param int    $post_id Attachment ID.
         */
        $url = apply_filters( 'wp_get_attachment_url', $url, $post->ID );

        if ( empty( $url ) )
                return false;

        return $url;
}

/**
 * Retrieve thumbnail for an attachment.
 *
 * @since 2.1.0
 *
 * @param int $post_id Optional. Attachment ID. Default 0.
 * @return string|false False on failure. Thumbnail file path on success.
 */
function wp_get_attachment_thumb_file( $post_id = 0 ) {
        $post_id = (int) $post_id;
        if ( !$post = get_post( $post_id ) )
                return false;
        if ( !is_array( $imagedata = wp_get_attachment_metadata( $post->ID ) ) )
                return false;

        $file = get_attached_file( $post->ID );

        if ( !empty($imagedata['thumb']) && ($thumbfile = str_replace(basename($file), $imagedata['thumb'], $file)) && file_exists($thumbfile) ) {
                /**
                 * Filter the attachment thumbnail file path.
                 *
                 * @since 2.1.0
                 *
                 * @param string $thumbfile File path to the attachment thumbnail.
                 * @param int    $post_id   Attachment ID.
                 */
                return apply_filters( 'wp_get_attachment_thumb_file', $thumbfile, $post->ID );
        }
        return false;
}

/**
 * Retrieve URL for an attachment thumbnail.
 *
 * @since 2.1.0
 *
 * @param int $post_id Optional. Attachment ID. Default 0.
 * @return string|false False on failure. Thumbnail URL on success.
 */
function wp_get_attachment_thumb_url( $post_id = 0 ) {
        $post_id = (int) $post_id;
        if ( !$post = get_post( $post_id ) )
                return false;
        if ( !$url = wp_get_attachment_url( $post->ID ) )
                return false;

        $sized = image_downsize( $post_id, 'thumbnail' );
        if ( $sized )
                return $sized[0];

        if ( !$thumb = wp_get_attachment_thumb_file( $post->ID ) )
                return false;

        $url = str_replace(basename($url), basename($thumb), $url);

        /**
         * Filter the attachment thumbnail URL.
         *
         * @since 2.1.0
         *
         * @param string $url     URL for the attachment thumbnail.
         * @param int    $post_id Attachment ID.
         */
        return apply_filters( 'wp_get_attachment_thumb_url', $url, $post->ID );
}

/**
 * Verifies an attachment is of a given type.
 *
 * @since 4.2.0
 *
 * @param string      $type    Attachment type. Accepts 'image', 'audio', or 'video'.
 * @param int|WP_Post $post_id Optional. Attachment ID. Default 0.
 * @return bool True if one of the accepted types, false otherwise.
 */
function wp_attachment_is( $type, $post_id = 0 ) {
        if ( ! $post = get_post( $post_id ) ) {
                return false;
        }

        if ( ! $file = get_attached_file( $post->ID ) ) {
                return false;
        }

        if ( 0 === strpos( $post->post_mime_type, $type . '/' ) ) {
                return true;
        }

        $check = wp_check_filetype( $file );
        if ( empty( $check['ext'] ) ) {
                return false;
        }

        $ext = $check['ext'];

        if ( 'import' !== $post->post_mime_type ) {
                return $type === $ext;
        }

        switch ( $type ) {
        case 'image':
                $image_exts = array( 'jpg', 'jpeg', 'jpe', 'gif', 'png' );
                return in_array( $ext, $image_exts );

        case 'audio':
                return in_array( $ext, wp_get_audio_extensions() );

        case 'video':
                return in_array( $ext, wp_get_video_extensions() );

        default:
                return $type === $ext;
        }
}

/**
 * Checks if the attachment is an image.
 *
 * @since 2.1.0
 * @since 4.2.0 Modified into wrapper for wp_attachment_is() and
 *              allowed WP_Post object to be passed.
 *
 * @param int|WP_Post $post Optional. Attachment ID. Default 0.
 * @return bool Whether the attachment is an image.
 */
function wp_attachment_is_image( $post = 0 ) {
        return wp_attachment_is( 'image', $post );
}

/**
 * Retrieve the icon for a MIME type.
 *
 * @since 2.1.0
 *
 * @param string|int $mime MIME type or attachment ID.
 * @return string|false Icon, false otherwise.
 */
function wp_mime_type_icon( $mime = 0 ) {
        if ( !is_numeric($mime) )
                $icon = wp_cache_get("mime_type_icon_$mime");

        $post_id = 0;
        if ( empty($icon) ) {
                $post_mimes = array();
                if ( is_numeric($mime) ) {
                        $mime = (int) $mime;
                        if ( $post = get_post( $mime ) ) {
                                $post_id = (int) $post->ID;
                                $file = get_attached_file( $post_id );
                                $ext = preg_replace('/^.+?\.([^.]+)$/', '$1', $file);
                                if ( !empty($ext) ) {
                                        $post_mimes[] = $ext;
                                        if ( $ext_type = wp_ext2type( $ext ) )
                                                $post_mimes[] = $ext_type;
                                }
                                $mime = $post->post_mime_type;
                        } else {
                                $mime = 0;
                        }
                } else {
                        $post_mimes[] = $mime;
                }

                $icon_files = wp_cache_get('icon_files');

                if ( !is_array($icon_files) ) {
                        /**
                         * Filter the icon directory path.
                         *
                         * @since 2.0.0
                         *
                         * @param string $path Icon directory absolute path.
                         */
                        $icon_dir = apply_filters( 'icon_dir', ABSPATH . WPINC . '/images/media' );

                        /**
                         * Filter the icon directory URI.
                         *
                         * @since 2.0.0
                         *
                         * @param string $uri Icon directory URI.
                         */
                        $icon_dir_uri = apply_filters( 'icon_dir_uri', includes_url( 'images/media' ) );

                        /**
                         * Filter the list of icon directory URIs.
                         *
                         * @since 2.5.0
                         *
                         * @param array $uris List of icon directory URIs.
                         */
                        $dirs = apply_filters( 'icon_dirs', array( $icon_dir => $icon_dir_uri ) );
                        $icon_files = array();
                        while ( $dirs ) {
                                $keys = array_keys( $dirs );
                                $dir = array_shift( $keys );
                                $uri = array_shift($dirs);
                                if ( $dh = opendir($dir) ) {
                                        while ( false !== $file = readdir($dh) ) {
                                                $file = basename($file);
                                                if ( substr($file, 0, 1) == '.' )
                                                        continue;
                                                if ( !in_array(strtolower(substr($file, -4)), array('.png', '.gif', '.jpg') ) ) {
                                                        if ( is_dir("$dir/$file") )
                                                                $dirs["$dir/$file"] = "$uri/$file";
                                                        continue;
                                                }
                                                $icon_files["$dir/$file"] = "$uri/$file";
                                        }
                                        closedir($dh);
                                }
                        }
                        wp_cache_add( 'icon_files', $icon_files, 'default', 600 );
                }

                $types = array();
                // Icon basename - extension = MIME wildcard.
                foreach ( $icon_files as $file => $uri )
                        $types[ preg_replace('/^([^.]*).*$/', '$1', basename($file)) ] =& $icon_files[$file];

                if ( ! empty($mime) ) {
                        $post_mimes[] = substr($mime, 0, strpos($mime, '/'));
                        $post_mimes[] = substr($mime, strpos($mime, '/') + 1);
                        $post_mimes[] = str_replace('/', '_', $mime);
                }

                $matches = wp_match_mime_types(array_keys($types), $post_mimes);
                $matches['default'] = array('default');

                foreach ( $matches as $match => $wilds ) {
                        foreach ( $wilds as $wild ) {
                                if ( ! isset( $types[ $wild ] ) ) {
                                        continue;
                                }

                                $icon = $types[ $wild ];
                                if ( ! is_numeric( $mime ) ) {
                                        wp_cache_add( "mime_type_icon_$mime", $icon );
                                }
                                break 2;
                        }
                }
        }

        /**
         * Filter the mime type icon.
         *
         * @since 2.1.0
         *
         * @param string $icon    Path to the mime type icon.
         * @param string $mime    Mime type.
         * @param int    $post_id Attachment ID. Will equal 0 if the function passed
         *                        the mime type.
         */
        return apply_filters( 'wp_mime_type_icon', $icon, $mime, $post_id );
}

/**
 * Check for changed slugs for published post objects and save the old slug.
 *
 * The function is used when a post object of any type is updated,
 * by comparing the current and previous post objects.
 *
 * If the slug was changed and not already part of the old slugs then it will be
 * added to the post meta field ('_wp_old_slug') for storing old slugs for that
 * post.
 *
 * The most logically usage of this function is redirecting changed post objects, so
 * that those that linked to an changed post will be redirected to the new post.
 *
 * @since 2.1.0
 *
 * @param int     $post_id     Post ID.
 * @param WP_Post $post        The Post Object
 * @param WP_Post $post_before The Previous Post Object
 */
function wp_check_for_changed_slugs( $post_id, $post, $post_before ) {
        // Don't bother if it hasn't changed.
        if ( $post->post_name == $post_before->post_name ) {
                return;
        }

        // We're only concerned with published, non-hierarchical objects.
        if ( ! ( 'publish' === $post->post_status || ( 'attachment' === get_post_type( $post ) && 'inherit' === $post->post_status ) ) || is_post_type_hierarchical( $post->post_type ) ) {
                return;
        }

        $old_slugs = (array) get_post_meta( $post_id, '_wp_old_slug' );

        // If we haven't added this old slug before, add it now.
        if ( ! empty( $post_before->post_name ) && ! in_array( $post_before->post_name, $old_slugs ) ) {
                add_post_meta( $post_id, '_wp_old_slug', $post_before->post_name );
        }

        // If the new slug was used previously, delete it from the list.
        if ( in_array( $post->post_name, $old_slugs ) ) {
                delete_post_meta( $post_id, '_wp_old_slug', $post->post_name );
        }
}

/**
 * Retrieve the private post SQL based on capability.
 *
 * This function provides a standardized way to appropriately select on the
 * post_status of a post type. The function will return a piece of SQL code
 * that can be added to a WHERE clause; this SQL is constructed to allow all
 * published posts, and all private posts to which the user has access.
 *
 * @since 2.2.0
 * @since 4.3.0 Added the ability to pass an array to `$post_type`.
 *
 * @param string|array $post_type Single post type or an array of post types. Currently only supports 'post' or 'page'.
 * @return string SQL code that can be added to a where clause.
 */
function get_private_posts_cap_sql( $post_type ) {
        return get_posts_by_author_sql( $post_type, false );
}

/**
 * Retrieve the post SQL based on capability, author, and type.
 *
 * @since 3.0.0
 * @since 4.3.0 Introduced the ability to pass an array of post types to `$post_type`.
 *
 * @see get_private_posts_cap_sql()
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param array|string   $post_type   Single post type or an array of post types.
 * @param bool           $full        Optional. Returns a full WHERE statement instead of just
 *                                    an 'andalso' term. Default true.
 * @param int            $post_author Optional. Query posts having a single author ID. Default null.
 * @param bool           $public_only Optional. Only return public posts. Skips cap checks for
 *                                    $current_user.  Default false.
 * @return string SQL WHERE code that can be added to a query.
 */
function get_posts_by_author_sql( $post_type, $full = true, $post_author = null, $public_only = false ) {
        global $wpdb;

        if ( is_array( $post_type ) ) {
                $post_types = $post_type;
        } else {
                $post_types = array( $post_type );
        }

        $post_type_clauses = array();
        foreach ( $post_types as $post_type ) {
                $post_type_obj = get_post_type_object( $post_type );
                if ( ! $post_type_obj ) {
                        continue;
                }

                /**
                 * Filter the capability to read private posts for a custom post type
                 * when generating SQL for getting posts by author.
                 *
                 * @since 2.2.0
                 * @deprecated 3.2.0 The hook transitioned from "somewhat useless" to "totally useless".
                 *
                 * @param string $cap Capability.
                 */
                if ( ! $cap = apply_filters( 'pub_priv_sql_capability', '' ) ) {
                        $cap = current_user_can( $post_type_obj->cap->read_private_posts );
                }

                // Only need to check the cap if $public_only is false.
                $post_status_sql = "post_status = 'publish'";
                if ( false === $public_only ) {
                        if ( $cap ) {
                                // Does the user have the capability to view private posts? Guess so.
                                $post_status_sql .= " OR post_status = 'private'";
                        } elseif ( is_user_logged_in() ) {
                                // Users can view their own private posts.
                                $id = get_current_user_id();
                                if ( null === $post_author || ! $full ) {
                                        $post_status_sql .= " OR post_status = 'private' AND post_author = $id";
                                } elseif ( $id == (int) $post_author ) {
                                        $post_status_sql .= " OR post_status = 'private'";
                                } // else none
                        } // else none
                }

                $post_type_clauses[] = "( post_type = '" . $post_type . "' AND ( $post_status_sql ) )";
        }

        if ( empty( $post_type_clauses ) ) {
                return $full ? 'WHERE 1 = 0' : '1 = 0';
        }

        $sql = '( '. implode( ' OR ', $post_type_clauses ) . ' )';

        if ( null !== $post_author ) {
                $sql .= $wpdb->prepare( ' AND post_author = %d', $post_author );
        }

        if ( $full ) {
                $sql = 'WHERE ' . $sql;
        }

        return $sql;
}

/**
 * Retrieve the date that the last post was published.
 *
 * The server timezone is the default and is the difference between GMT and
 * server time. The 'blog' value is the date when the last post was posted. The
 * 'gmt' is when the last post was posted in GMT formatted date.
 *
 * @since 0.71
 * @since 4.4.0 The `$post_type` argument was added.
 *
 * @param string $timezone  Optional. The timezone for the timestamp. Accepts 'server', 'blog', or 'gmt'.
 *                          'server' uses the server's internal timezone.
 *                          'blog' uses the `post_modified` field, which proxies to the timezone set for the site.
 *                          'gmt' uses the `post_modified_gmt` field.
 *                          Default 'server'.
 * @param string $post_type Optional. The post type to check. Default 'any'.
 * @return string The date of the last post.
 */
function get_lastpostdate( $timezone = 'server', $post_type = 'any' ) {
        /**
         * Filter the date the last post was published.
         *
         * @since 2.3.0
         *
         * @param string $date     Date the last post was published.
         * @param string $timezone Location to use for getting the post published date.
         *                         See {@see get_lastpostdate()} for accepted `$timezone` values.
         */
        return apply_filters( 'get_lastpostdate', _get_last_post_time( $timezone, 'date', $post_type ), $timezone );
}

/**
 * Get the timestamp of the last time any post was modified.
 *
 * The server timezone is the default and is the difference between GMT and
 * server time. The 'blog' value is just when the last post was modified. The
 * 'gmt' is when the last post was modified in GMT time.
 *
 * @since 1.2.0
 * @since 4.4.0 The `$post_type` argument was added.
 *
 * @param string $timezone  Optional. The timezone for the timestamp. See {@see get_lastpostdate()}
 *                          for information on accepted values.
 *                          Default 'server'.
 * @param string $post_type Optional. The post type to check. Default 'any'.
 * @return string The timestamp.
 */
function get_lastpostmodified( $timezone = 'server', $post_type = 'any' ) {
        /**
         * Pre-filter the return value of get_lastpostmodified() before the query is run.
         *
         * @since 4.4.0
         *
         * @param string $lastpostmodified Date the last post was modified.
         *                                 Returning anything other than false will short-circuit the function.
         * @param string $timezone         Location to use for getting the post modified date.
         *                                 See {@see get_lastpostdate()} for accepted `$timezone` values.
         * @param string $post_type        The post type to check.
         */
        $lastpostmodified = apply_filters( 'pre_get_lastpostmodified', false, $timezone, $post_type );
        if ( false !== $lastpostmodified ) {
                return $lastpostmodified;
        }

        $lastpostmodified = _get_last_post_time( $timezone, 'modified', $post_type );

        $lastpostdate = get_lastpostdate($timezone);
        if ( $lastpostdate > $lastpostmodified ) {
                $lastpostmodified = $lastpostdate;
        }

        /**
         * Filter the date the last post was modified.
         *
         * @since 2.3.0
         *
         * @param string $lastpostmodified Date the last post was modified.
         * @param string $timezone         Location to use for getting the post modified date.
         *                                 See {@see get_lastpostdate()} for accepted `$timezone` values.
         */
        return apply_filters( 'get_lastpostmodified', $lastpostmodified, $timezone );
}

/**
 * Get the timestamp of the last time any post was modified or published.
 *
 * @since 3.1.0
 * @since 4.4.0 The `$post_type` argument was added.
 * @access private
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $timezone  The timezone for the timestamp. See get_lastpostdate().
 *                          for information on accepted values.
 * @param string $field     Post field to check. Accepts 'date' or 'modified'.
 * @param string $post_type Optional. The post type to check. Default 'any'.
 * @return string|false The timestamp.
 */
function _get_last_post_time( $timezone, $field, $post_type = 'any' ) {
        global $wpdb;

        if ( ! in_array( $field, array( 'date', 'modified' ) ) ) {
                return false;
        }

        $timezone = strtolower( $timezone );

        $key = "lastpost{$field}:$timezone";
        if ( 'any' !== $post_type ) {
                $key .= ':' . sanitize_key( $post_type );
        }

        $date = wp_cache_get( $key, 'timeinfo' );

        if ( ! $date ) {
                if ( 'any' === $post_type ) {
                        $post_types = get_post_types( array( 'public' => true ) );
                        array_walk( $post_types, array( $wpdb, 'escape_by_ref' ) );
                        $post_types = "'" . implode( "', '", $post_types ) . "'";
                } else {
                        $post_types = "'" . sanitize_key( $post_type ) . "'";
                }

                switch ( $timezone ) {
                        case 'gmt':
                                $date = $wpdb->get_var("SELECT post_{$field}_gmt FROM $wpdb->posts WHERE post_status = 'publish' AND post_type IN ({$post_types}) ORDER BY post_{$field}_gmt DESC LIMIT 1");
                                break;
                        case 'blog':
                                $date = $wpdb->get_var("SELECT post_{$field} FROM $wpdb->posts WHERE post_status = 'publish' AND post_type IN ({$post_types}) ORDER BY post_{$field}_gmt DESC LIMIT 1");
                                break;
                        case 'server':
                                $add_seconds_server = date( 'Z' );
                                $date = $wpdb->get_var("SELECT DATE_ADD(post_{$field}_gmt, INTERVAL '$add_seconds_server' SECOND) FROM $wpdb->posts WHERE post_status = 'publish' AND post_type IN ({$post_types}) ORDER BY post_{$field}_gmt DESC LIMIT 1");
                                break;
                }

                if ( $date ) {
                        wp_cache_set( $key, $date, 'timeinfo' );
                }
        }

        return $date;
}

/**
 * Updates posts in cache.
 *
 * @since 1.5.1
 *
 * @param array $posts Array of post objects, passed by reference.
 */
function update_post_cache( &$posts ) {
        if ( ! $posts )
                return;

        foreach ( $posts as $post )
                wp_cache_add( $post->ID, $post, 'posts' );
}

/**
 * Will clean the post in the cache.
 *
 * Cleaning means delete from the cache of the post. Will call to clean the term
 * object cache associated with the post ID.
 *
 * This function not run if $_wp_suspend_cache_invalidation is not empty. See
 * wp_suspend_cache_invalidation().
 *
 * @since 2.0.0
 *
 * @global bool $_wp_suspend_cache_invalidation
 *
 * @param int|WP_Post $post Post ID or post object to remove from the cache.
 */
function clean_post_cache( $post ) {
        global $_wp_suspend_cache_invalidation;

        if ( ! empty( $_wp_suspend_cache_invalidation ) )
                return;

        $post = get_post( $post );
        if ( empty( $post ) )
                return;

        wp_cache_delete( $post->ID, 'posts' );
        wp_cache_delete( $post->ID, 'post_meta' );

        clean_object_term_cache( $post->ID, $post->post_type );

        wp_cache_delete( 'wp_get_archives', 'general' );

        /**
         * Fires immediately after the given post's cache is cleaned.
         *
         * @since 2.5.0
         *
         * @param int     $post_id Post ID.
         * @param WP_Post $post    Post object.
         */
        do_action( 'clean_post_cache', $post->ID, $post );

        if ( 'page' == $post->post_type ) {
                wp_cache_delete( 'all_page_ids', 'posts' );

                /**
                 * Fires immediately after the given page's cache is cleaned.
                 *
                 * @since 2.5.0
                 *
                 * @param int $post_id Post ID.
                 */
                do_action( 'clean_page_cache', $post->ID );
        }

        wp_cache_set( 'last_changed', microtime(), 'posts' );
}

/**
 * Call major cache updating functions for list of Post objects.
 *
 * @since 1.5.0
 *
 * @param array  $posts             Array of Post objects
 * @param string $post_type         Optional. Post type. Default 'post'.
 * @param bool   $update_term_cache Optional. Whether to update the term cache. Default true.
 * @param bool   $update_meta_cache Optional. Whether to update the meta cache. Default true.
 */
function update_post_caches( &$posts, $post_type = 'post', $update_term_cache = true, $update_meta_cache = true ) {
        // No point in doing all this work if we didn't match any posts.
        if ( !$posts )
                return;

        update_post_cache($posts);

        $post_ids = array();
        foreach ( $posts as $post )
                $post_ids[] = $post->ID;

        if ( ! $post_type )
                $post_type = 'any';

        if ( $update_term_cache ) {
                if ( is_array($post_type) ) {
                        $ptypes = $post_type;
                } elseif ( 'any' == $post_type ) {
                        $ptypes = array();
                        // Just use the post_types in the supplied posts.
                        foreach ( $posts as $post ) {
                                $ptypes[] = $post->post_type;
                        }
                        $ptypes = array_unique($ptypes);
                } else {
                        $ptypes = array($post_type);
                }

                if ( ! empty($ptypes) )
                        update_object_term_cache($post_ids, $ptypes);
        }

        if ( $update_meta_cache )
                update_postmeta_cache($post_ids);
}

/**
 * Updates metadata cache for list of post IDs.
 *
 * Performs SQL query to retrieve the metadata for the post IDs and updates the
 * metadata cache for the posts. Therefore, the functions, which call this
 * function, do not need to perform SQL queries on their own.
 *
 * @since 2.1.0
 *
 * @param array $post_ids List of post IDs.
 * @return array|false Returns false if there is nothing to update or an array
 *                     of metadata.
 */
function update_postmeta_cache( $post_ids ) {
        return update_meta_cache('post', $post_ids);
}

/**
 * Will clean the attachment in the cache.
 *
 * Cleaning means delete from the cache. Optionally will clean the term
 * object cache associated with the attachment ID.
 *
 * This function will not run if $_wp_suspend_cache_invalidation is not empty.
 *
 * @since 3.0.0
 *
 * @global bool $_wp_suspend_cache_invalidation
 *
 * @param int  $id          The attachment ID in the cache to clean.
 * @param bool $clean_terms Optional. Whether to clean terms cache. Default false.
 */
function clean_attachment_cache( $id, $clean_terms = false ) {
        global $_wp_suspend_cache_invalidation;

        if ( !empty($_wp_suspend_cache_invalidation) )
                return;

        $id = (int) $id;

        wp_cache_delete($id, 'posts');
        wp_cache_delete($id, 'post_meta');

        if ( $clean_terms )
                clean_object_term_cache($id, 'attachment');

        /**
         * Fires after the given attachment's cache is cleaned.
         *
         * @since 3.0.0
         *
         * @param int $id Attachment ID.
         */
        do_action( 'clean_attachment_cache', $id );
}

//
// Hooks
//

/**
 * Hook for managing future post transitions to published.
 *
 * @since 2.3.0
 * @access private
 *
 * @see wp_clear_scheduled_hook()
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string  $new_status New post status.
 * @param string  $old_status Previous post status.
 * @param WP_Post $post       Post object.
 */
function _transition_post_status( $new_status, $old_status, $post ) {
        global $wpdb;

        if ( $old_status != 'publish' && $new_status == 'publish' ) {
                // Reset GUID if transitioning to publish and it is empty.
                if ( '' == get_the_guid($post->ID) )
                        $wpdb->update( $wpdb->posts, array( 'guid' => get_permalink( $post->ID ) ), array( 'ID' => $post->ID ) );

                /**
                 * Fires when a post's status is transitioned from private to published.
                 *
                 * @since 1.5.0
                 * @deprecated 2.3.0 Use 'private_to_publish' instead.
                 *
                 * @param int $post_id Post ID.
                 */
                do_action('private_to_published', $post->ID);
        }

        // If published posts changed clear the lastpostmodified cache.
        if ( 'publish' == $new_status || 'publish' == $old_status) {
                foreach ( array( 'server', 'gmt', 'blog' ) as $timezone ) {
                        wp_cache_delete( "lastpostmodified:$timezone", 'timeinfo' );
                        wp_cache_delete( "lastpostdate:$timezone", 'timeinfo' );
                        wp_cache_delete( "lastpostdate:$timezone:{$post->post_type}", 'timeinfo' );
                }
        }

        if ( $new_status !== $old_status ) {
                wp_cache_delete( _count_posts_cache_key( $post->post_type ), 'counts' );
                wp_cache_delete( _count_posts_cache_key( $post->post_type, 'readable' ), 'counts' );
        }

        // Always clears the hook in case the post status bounced from future to draft.
        wp_clear_scheduled_hook('publish_future_post', array( $post->ID ) );
}

/**
 * Hook used to schedule publication for a post marked for the future.
 *
 * The $post properties used and must exist are 'ID' and 'post_date_gmt'.
 *
 * @since 2.3.0
 * @access private
 *
 * @param int     $deprecated Not used. Can be set to null. Never implemented. Not marked
 *                            as deprecated with _deprecated_argument() as it conflicts with
 *                            wp_transition_post_status() and the default filter for
 *                            {@see _future_post_hook()}.
 * @param WP_Post $post       Post object.
 */
function _future_post_hook( $deprecated, $post ) {
        wp_clear_scheduled_hook( 'publish_future_post', array( $post->ID ) );
        wp_schedule_single_event( strtotime( get_gmt_from_date( $post->post_date ) . ' GMT') , 'publish_future_post', array( $post->ID ) );
}

/**
 * Hook to schedule pings and enclosures when a post is published.
 *
 * Uses XMLRPC_REQUEST and WP_IMPORTING constants.
 *
 * @since 2.3.0
 * @access private
 *
 * @param int $post_id The ID in the database table of the post being published.
 */
function _publish_post_hook( $post_id ) {
        if ( defined( 'XMLRPC_REQUEST' ) ) {
                /**
                 * Fires when _publish_post_hook() is called during an XML-RPC request.
                 *
                 * @since 2.1.0
                 *
                 * @param int $post_id Post ID.
                 */
                do_action( 'xmlrpc_publish_post', $post_id );
        }

        if ( defined('WP_IMPORTING') )
                return;

        if ( get_option('default_pingback_flag') )
                add_post_meta( $post_id, '_pingme', '1' );
        add_post_meta( $post_id, '_encloseme', '1' );

        wp_schedule_single_event(time(), 'do_pings');
}

/**
 * Return the post's parent's post_ID
 *
 * @since 3.1.0
 *
 * @param int $post_ID
 *
 * @return int|false Post parent ID, otherwise false.
 */
function wp_get_post_parent_id( $post_ID ) {
        $post = get_post( $post_ID );
        if ( !$post || is_wp_error( $post ) )
                return false;
        return (int) $post->post_parent;
}

/**
 * Check the given subset of the post hierarchy for hierarchy loops.
 *
 * Prevents loops from forming and breaks those that it finds. Attached
 * to the 'wp_insert_post_parent' filter.
 *
 * @since 3.1.0
 *
 * @see wp_find_hierarchy_loop()
 *
 * @param int $post_parent ID of the parent for the post we're checking.
 * @param int $post_ID     ID of the post we're checking.
 * @return int The new post_parent for the post, 0 otherwise.
 */
function wp_check_post_hierarchy_for_loops( $post_parent, $post_ID ) {
        // Nothing fancy here - bail.
        if ( !$post_parent )
                return 0;

        // New post can't cause a loop.
        if ( empty( $post_ID ) )
                return $post_parent;

        // Can't be its own parent.
        if ( $post_parent == $post_ID )
                return 0;

        // Now look for larger loops.
        if ( !$loop = wp_find_hierarchy_loop( 'wp_get_post_parent_id', $post_ID, $post_parent ) )
                return $post_parent; // No loop

        // Setting $post_parent to the given value causes a loop.
        if ( isset( $loop[$post_ID] ) )
                return 0;

        // There's a loop, but it doesn't contain $post_ID. Break the loop.
        foreach ( array_keys( $loop ) as $loop_member )
                wp_update_post( array( 'ID' => $loop_member, 'post_parent' => 0 ) );

        return $post_parent;
}

/**
 * Set a post thumbnail.
 *
 * @since 3.1.0
 *
 * @param int|WP_Post $post         Post ID or post object where thumbnail should be attached.
 * @param int         $thumbnail_id Thumbnail to attach.
 * @return int|bool True on success, false on failure.
 */
function set_post_thumbnail( $post, $thumbnail_id ) {
        $post = get_post( $post );
        $thumbnail_id = absint( $thumbnail_id );
        if ( $post && $thumbnail_id && get_post( $thumbnail_id ) ) {
                if ( wp_get_attachment_image( $thumbnail_id, 'thumbnail' ) )
                        return update_post_meta( $post->ID, '_thumbnail_id', $thumbnail_id );
                else
                        return delete_post_meta( $post->ID, '_thumbnail_id' );
        }
        return false;
}

/**
 * Remove a post thumbnail.
 *
 * @since 3.3.0
 *
 * @param int|WP_Post $post Post ID or post object where thumbnail should be removed from.
 * @return bool True on success, false on failure.
 */
function delete_post_thumbnail( $post ) {
        $post = get_post( $post );
        if ( $post )
                return delete_post_meta( $post->ID, '_thumbnail_id' );
        return false;
}

/**
 * Delete auto-drafts for new posts that are > 7 days old.
 *
 * @since 3.4.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 */
function wp_delete_auto_drafts() {
        global $wpdb;

        // Cleanup old auto-drafts more than 7 days old.
        $old_posts = $wpdb->get_col( "SELECT ID FROM $wpdb->posts WHERE post_status = 'auto-draft' AND DATE_SUB( NOW(), INTERVAL 7 DAY ) > post_date" );
        foreach ( (array) $old_posts as $delete ) {
                // Force delete.
                wp_delete_post( $delete, true );
        }
}

/**
 * Queues posts for lazy-loading of term meta.
 *
 * @since 4.5.0
 *
 * @param array $posts Array of WP_Post objects.
 */
function wp_queue_posts_for_term_meta_lazyload( $posts ) {
        $post_type_taxonomies = $term_ids = array();
        foreach ( $posts as $post ) {
                if ( ! ( $post instanceof WP_Post ) ) {
                        continue;
                }

                if ( ! isset( $post_type_taxonomies[ $post->post_type ] ) ) {
                        $post_type_taxonomies[ $post->post_type ] = get_object_taxonomies( $post->post_type );
                }

                foreach ( $post_type_taxonomies[ $post->post_type ] as $taxonomy ) {
                        // Term cache should already be primed by `update_post_term_cache()`.
                        $terms = get_object_term_cache( $post->ID, $taxonomy );
                        if ( false !== $terms ) {
                                foreach ( $terms as $term ) {
                                        if ( ! isset( $term_ids[ $term->term_id ] ) ) {
                                                $term_ids[] = $term->term_id;
                                        }
                                }
                        }
                }
        }

        if ( $term_ids ) {
                $lazyloader = wp_metadata_lazyloader();
                $lazyloader->queue_objects( 'term', $term_ids );
        }
}

/**
 * Update the custom taxonomies' term counts when a post's status is changed.
 *
 * For example, default posts term counts (for custom taxonomies) don't include
 * private / draft posts.
 *
 * @since 3.3.0
 * @access private
 *
 * @param string  $new_status New post status.
 * @param string  $old_status Old post status.
 * @param WP_Post $post       Post object.
 */
function _update_term_count_on_transition_post_status( $new_status, $old_status, $post ) {
        // Update counts for the post's terms.
        foreach ( (array) get_object_taxonomies( $post->post_type ) as $taxonomy ) {
                $tt_ids = wp_get_object_terms( $post->ID, $taxonomy, array( 'fields' => 'tt_ids' ) );
                wp_update_term_count( $tt_ids, $taxonomy );
        }
}

/**
 * Adds any posts from the given ids to the cache that do not already exist in cache
 *
 * @since 3.4.0
 * @access private
 *
 * @see update_post_caches()
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param array $ids               ID list.
 * @param bool  $update_term_cache Optional. Whether to update the term cache. Default true.
 * @param bool  $update_meta_cache Optional. Whether to update the meta cache. Default true.
 */
function _prime_post_caches( $ids, $update_term_cache = true, $update_meta_cache = true ) {
        global $wpdb;

        $non_cached_ids = _get_non_cached_ids( $ids, 'posts' );
        if ( !empty( $non_cached_ids ) ) {
                $fresh_posts = $wpdb->get_results( sprintf( "SELECT $wpdb->posts.* FROM $wpdb->posts WHERE ID IN (%s)", join( ",", $non_cached_ids ) ) );

                update_post_caches( $fresh_posts, 'any', $update_term_cache, $update_meta_cache );
        }
}

/**
 * Adds a suffix if any trashed posts have a given slug.
 *
 * Store its desired (i.e. current) slug so it can try to reclaim it
 * if the post is untrashed.
 *
 * For internal use.
 *
 * @since 4.5.0
 * @access private
 *
 * @param string $post_name Slug.
 * @param string $post_ID   Optional. Post ID that should be ignored. Default 0.
 */
function wp_add_trashed_suffix_to_post_name_for_trashed_posts( $post_name, $post_ID = 0 ) {
        $trashed_posts_with_desired_slug = get_posts( array(
                'name' => $post_name,
                'post_status' => 'trash',
                'post_type' => 'any',
                'nopaging' => true,
                'post__not_in' => array( $post_ID )
        ) );

        if ( ! empty( $trashed_posts_with_desired_slug ) ) {
                foreach ( $trashed_posts_with_desired_slug as $_post ) {
                        wp_add_trashed_suffix_to_post_name_for_post( $_post );
                }
        }
}

/**
 * Adds a trashed suffix For a given post.
 *
 * Store its desired (i.e. current) slug so it can try to reclaim it
 * if the post is untrashed.
 *
 * For internal use.
 *
 * @since 4.5.0
 * @access private
 *
 * @param WP_Post $post The post.
 */
function wp_add_trashed_suffix_to_post_name_for_post( $post ) {
        global $wpdb;

        $post = get_post( $post );

        if ( '__trashed' === substr( $post->post_name, -9 ) ) {
                return $post->post_name;
        }
        add_post_meta( $post->ID, '_wp_desired_post_slug', $post->post_name );
        $post_name = _truncate_post_slug( $post->post_name, 191 ) . '__trashed';
        $wpdb->update( $wpdb->posts, array( 'post_name' => $post_name ), array( 'ID' => $post->ID ) );
        clean_post_cache( $post->ID );
        return $post_name;
}