+/**
+ * Returns a shortlink for a post, page, attachment, or site.
+ *
+ * This function exists to provide a shortlink tag that all themes and plugins can target.
+ * A plugin must hook in to provide the actual shortlinks. Default shortlink support is
+ * limited to providing ?p= style links for posts. Plugins can short-circuit this function
+ * via the {@see 'pre_get_shortlink'} filter or filter the output via the {@see 'get_shortlink'}
+ * filter.
+ *
+ * @since 3.0.0.
+ *
+ * @param int $id Optional. A post or site id. Default is 0, which means the current post or site.
+ * @param string $context Optional. Whether the id is a 'site' id, 'post' id, or 'media' id. If 'post',
+ * the post_type of the post is consulted. If 'query', the current query is consulted
+ * to determine the id and context. Default 'post'.
+ * @param bool $allow_slugs Optional. Whether to allow post slugs in the shortlink. It is up to the plugin how
+ * and whether to honor this. Default true.
+ * @return string A shortlink or an empty string if no shortlink exists for the requested resource or if shortlinks
+ * are not enabled.
+ */
+function wp_get_shortlink( $id = 0, $context = 'post', $allow_slugs = true ) {
+ /**
+ * Filters whether to preempt generating a shortlink for the given post.
+ *
+ * Passing a truthy value to the filter will effectively short-circuit the
+ * shortlink-generation process, returning that value instead.
+ *
+ * @since 3.0.0
+ *
+ * @param bool|string $return Short-circuit return value. Either false or a URL string.
+ * @param int $id Post ID, or 0 for the current post.
+ * @param string $context The context for the link. One of 'post' or 'query',
+ * @param bool $allow_slugs Whether to allow post slugs in the shortlink.
+ */
+ $shortlink = apply_filters( 'pre_get_shortlink', false, $id, $context, $allow_slugs );
+
+ if ( false !== $shortlink ) {
+ return $shortlink;
+ }
+
+ $post_id = 0;
+ if ( 'query' == $context && is_singular() ) {
+ $post_id = get_queried_object_id();
+ $post = get_post( $post_id );
+ } elseif ( 'post' == $context ) {
+ $post = get_post( $id );
+ if ( ! empty( $post->ID ) )
+ $post_id = $post->ID;
+ }
+
+ $shortlink = '';
+
+ // Return p= link for all public post types.
+ if ( ! empty( $post_id ) ) {
+ $post_type = get_post_type_object( $post->post_type );
+
+ if ( 'page' === $post->post_type && $post->ID == get_option( 'page_on_front' ) && 'page' == get_option( 'show_on_front' ) ) {
+ $shortlink = home_url( '/' );
+ } elseif ( $post_type->public ) {
+ $shortlink = home_url( '?p=' . $post_id );
+ }
+ }
+
+ /**
+ * Filters the shortlink for a post.
+ *
+ * @since 3.0.0
+ *
+ * @param string $shortlink Shortlink URL.
+ * @param int $id Post ID, or 0 for the current post.
+ * @param string $context The context for the link. One of 'post' or 'query',
+ * @param bool $allow_slugs Whether to allow post slugs in the shortlink. Not used by default.
+ */
+ return apply_filters( 'get_shortlink', $shortlink, $id, $context, $allow_slugs );
+}
+
+/**
+ * Injects rel=shortlink into the head if a shortlink is defined for the current page.
+ *
+ * Attached to the {@see 'wp_head'} action.
+ *
+ * @since 3.0.0
+ */
+function wp_shortlink_wp_head() {
+ $shortlink = wp_get_shortlink( 0, 'query' );
+
+ if ( empty( $shortlink ) )
+ return;
+
+ echo "<link rel='shortlink' href='" . esc_url( $shortlink ) . "' />\n";
+}
+
+/**
+ * Sends a Link: rel=shortlink header if a shortlink is defined for the current page.
+ *
+ * Attached to the {@see 'wp'} action.
+ *
+ * @since 3.0.0
+ */
+function wp_shortlink_header() {
+ if ( headers_sent() )
+ return;
+
+ $shortlink = wp_get_shortlink(0, 'query');
+
+ if ( empty($shortlink) )
+ return;
+
+ header('Link: <' . $shortlink . '>; rel=shortlink', false);
+}
+
+/**
+ * Displays the shortlink for a post.
+ *
+ * Must be called from inside "The Loop"
+ *
+ * Call like the_shortlink( __( 'Shortlinkage FTW' ) )
+ *
+ * @since 3.0.0
+ *
+ * @param string $text Optional The link text or HTML to be displayed. Defaults to 'This is the short link.'
+ * @param string $title Optional The tooltip for the link. Must be sanitized. Defaults to the sanitized post title.
+ * @param string $before Optional HTML to display before the link. Default empty.
+ * @param string $after Optional HTML to display after the link. Default empty.
+ */
+function the_shortlink( $text = '', $title = '', $before = '', $after = '' ) {
+ $post = get_post();
+
+ if ( empty( $text ) )
+ $text = __('This is the short link.');
+
+ if ( empty( $title ) )
+ $title = the_title_attribute( array( 'echo' => false ) );
+
+ $shortlink = wp_get_shortlink( $post->ID );
+
+ if ( !empty( $shortlink ) ) {
+ $link = '<a rel="shortlink" href="' . esc_url( $shortlink ) . '" title="' . $title . '">' . $text . '</a>';
+
+ /**
+ * Filters the short link anchor tag for a post.
+ *
+ * @since 3.0.0
+ *
+ * @param string $link Shortlink anchor tag.
+ * @param string $shortlink Shortlink URL.
+ * @param string $text Shortlink's text.
+ * @param string $title Shortlink's title attribute.
+ */
+ $link = apply_filters( 'the_shortlink', $link, $shortlink, $text, $title );
+ echo $before, $link, $after;
+ }
+}
+
+
+/**
+ * Retrieves the avatar URL.
+ *
+ * @since 4.2.0
+ *
+ * @param mixed $id_or_email The Gravatar to retrieve a URL for. Accepts a user_id, gravatar md5 hash,
+ * user email, WP_User object, WP_Post object, or WP_Comment object.
+ * @param array $args {
+ * Optional. Arguments to return instead of the default arguments.
+ *
+ * @type int $size Height and width of the avatar in pixels. Default 96.
+ * @type string $default URL for the default image or a default type. Accepts '404' (return
+ * a 404 instead of a default image), 'retro' (8bit), 'monsterid' (monster),
+ * 'wavatar' (cartoon face), 'indenticon' (the "quilt"), 'mystery', 'mm',
+ * or 'mysteryman' (The Oyster Man), 'blank' (transparent GIF), or
+ * 'gravatar_default' (the Gravatar logo). Default is the value of the
+ * 'avatar_default' option, with a fallback of 'mystery'.
+ * @type bool $force_default Whether to always show the default image, never the Gravatar. Default false.
+ * @type string $rating What rating to display avatars up to. Accepts 'G', 'PG', 'R', 'X', and are
+ * judged in that order. Default is the value of the 'avatar_rating' option.
+ * @type string $scheme URL scheme to use. See set_url_scheme() for accepted values.
+ * Default null.
+ * @type array $processed_args When the function returns, the value will be the processed/sanitized $args
+ * plus a "found_avatar" guess. Pass as a reference. Default null.
+ * }
+ * @return false|string The URL of the avatar we found, or false if we couldn't find an avatar.
+ */
+function get_avatar_url( $id_or_email, $args = null ) {
+ $args = get_avatar_data( $id_or_email, $args );
+ return $args['url'];
+}
+
+/**
+ * Retrieves default data about the avatar.
+ *
+ * @since 4.2.0
+ *
+ * @param mixed $id_or_email The Gravatar to retrieve. Accepts a user_id, gravatar md5 hash,
+ * user email, WP_User object, WP_Post object, or WP_Comment object.
+ * @param array $args {
+ * Optional. Arguments to return instead of the default arguments.
+ *
+ * @type int $size Height and width of the avatar image file in pixels. Default 96.
+ * @type int $height Display height of the avatar in pixels. Defaults to $size.
+ * @type int $width Display width of the avatar in pixels. Defaults to $size.
+ * @type string $default URL for the default image or a default type. Accepts '404' (return
+ * a 404 instead of a default image), 'retro' (8bit), 'monsterid' (monster),
+ * 'wavatar' (cartoon face), 'indenticon' (the "quilt"), 'mystery', 'mm',
+ * or 'mysteryman' (The Oyster Man), 'blank' (transparent GIF), or
+ * 'gravatar_default' (the Gravatar logo). Default is the value of the
+ * 'avatar_default' option, with a fallback of 'mystery'.
+ * @type bool $force_default Whether to always show the default image, never the Gravatar. Default false.
+ * @type string $rating What rating to display avatars up to. Accepts 'G', 'PG', 'R', 'X', and are
+ * judged in that order. Default is the value of the 'avatar_rating' option.
+ * @type string $scheme URL scheme to use. See set_url_scheme() for accepted values.
+ * Default null.
+ * @type array $processed_args When the function returns, the value will be the processed/sanitized $args
+ * plus a "found_avatar" guess. Pass as a reference. Default null.
+ * @type string $extra_attr HTML attributes to insert in the IMG element. Is not sanitized. Default empty.
+ * }
+ * @return array $processed_args {
+ * Along with the arguments passed in `$args`, this will contain a couple of extra arguments.
+ *
+ * @type bool $found_avatar True if we were able to find an avatar for this user,
+ * false or not set if we couldn't.
+ * @type string $url The URL of the avatar we found.
+ * }
+ */
+function get_avatar_data( $id_or_email, $args = null ) {
+ $args = wp_parse_args( $args, array(
+ 'size' => 96,
+ 'height' => null,
+ 'width' => null,
+ 'default' => get_option( 'avatar_default', 'mystery' ),
+ 'force_default' => false,
+ 'rating' => get_option( 'avatar_rating' ),
+ 'scheme' => null,
+ 'processed_args' => null, // if used, should be a reference
+ 'extra_attr' => '',
+ ) );
+
+ if ( is_numeric( $args['size'] ) ) {
+ $args['size'] = absint( $args['size'] );
+ if ( ! $args['size'] ) {
+ $args['size'] = 96;
+ }
+ } else {
+ $args['size'] = 96;
+ }
+
+ if ( is_numeric( $args['height'] ) ) {
+ $args['height'] = absint( $args['height'] );
+ if ( ! $args['height'] ) {
+ $args['height'] = $args['size'];
+ }
+ } else {
+ $args['height'] = $args['size'];
+ }
+
+ if ( is_numeric( $args['width'] ) ) {
+ $args['width'] = absint( $args['width'] );
+ if ( ! $args['width'] ) {
+ $args['width'] = $args['size'];
+ }
+ } else {
+ $args['width'] = $args['size'];
+ }
+
+ if ( empty( $args['default'] ) ) {
+ $args['default'] = get_option( 'avatar_default', 'mystery' );
+ }
+
+ switch ( $args['default'] ) {
+ case 'mm' :
+ case 'mystery' :
+ case 'mysteryman' :
+ $args['default'] = 'mm';
+ break;
+ case 'gravatar_default' :
+ $args['default'] = false;
+ break;
+ }
+
+ $args['force_default'] = (bool) $args['force_default'];
+
+ $args['rating'] = strtolower( $args['rating'] );
+
+ $args['found_avatar'] = false;
+
+ /**
+ * Filters whether to retrieve the avatar URL early.
+ *
+ * Passing a non-null value in the 'url' member of the return array will
+ * effectively short circuit get_avatar_data(), passing the value through
+ * the {@see 'get_avatar_data'} filter and returning early.
+ *
+ * @since 4.2.0
+ *
+ * @param array $args Arguments passed to get_avatar_data(), after processing.
+ * @param mixed $id_or_email The Gravatar to retrieve. Accepts a user_id, gravatar md5 hash,
+ * user email, WP_User object, WP_Post object, or WP_Comment object.
+ */
+ $args = apply_filters( 'pre_get_avatar_data', $args, $id_or_email );
+
+ if ( isset( $args['url'] ) && ! is_null( $args['url'] ) ) {
+ /** This filter is documented in wp-includes/link-template.php */
+ return apply_filters( 'get_avatar_data', $args, $id_or_email );
+ }
+
+ $email_hash = '';
+ $user = $email = false;
+
+ if ( is_object( $id_or_email ) && isset( $id_or_email->comment_ID ) ) {
+ $id_or_email = get_comment( $id_or_email );
+ }
+
+ // Process the user identifier.
+ if ( is_numeric( $id_or_email ) ) {
+ $user = get_user_by( 'id', absint( $id_or_email ) );
+ } elseif ( is_string( $id_or_email ) ) {
+ if ( strpos( $id_or_email, '@md5.gravatar.com' ) ) {
+ // md5 hash
+ list( $email_hash ) = explode( '@', $id_or_email );
+ } else {
+ // email address
+ $email = $id_or_email;
+ }
+ } elseif ( $id_or_email instanceof WP_User ) {
+ // User Object
+ $user = $id_or_email;
+ } elseif ( $id_or_email instanceof WP_Post ) {
+ // Post Object
+ $user = get_user_by( 'id', (int) $id_or_email->post_author );
+ } elseif ( $id_or_email instanceof WP_Comment ) {
+ /**
+ * Filters the list of allowed comment types for retrieving avatars.
+ *
+ * @since 3.0.0
+ *
+ * @param array $types An array of content types. Default only contains 'comment'.
+ */
+ $allowed_comment_types = apply_filters( 'get_avatar_comment_types', array( 'comment' ) );
+ if ( ! empty( $id_or_email->comment_type ) && ! in_array( $id_or_email->comment_type, (array) $allowed_comment_types ) ) {
+ $args['url'] = false;
+ /** This filter is documented in wp-includes/link-template.php */
+ return apply_filters( 'get_avatar_data', $args, $id_or_email );
+ }
+
+ if ( ! empty( $id_or_email->user_id ) ) {
+ $user = get_user_by( 'id', (int) $id_or_email->user_id );
+ }
+ if ( ( ! $user || is_wp_error( $user ) ) && ! empty( $id_or_email->comment_author_email ) ) {
+ $email = $id_or_email->comment_author_email;
+ }
+ }
+
+ if ( ! $email_hash ) {
+ if ( $user ) {
+ $email = $user->user_email;
+ }
+
+ if ( $email ) {
+ $email_hash = md5( strtolower( trim( $email ) ) );
+ }
+ }
+
+ if ( $email_hash ) {
+ $args['found_avatar'] = true;
+ $gravatar_server = hexdec( $email_hash[0] ) % 3;
+ } else {
+ $gravatar_server = rand( 0, 2 );
+ }
+
+ $url_args = array(
+ 's' => $args['size'],
+ 'd' => $args['default'],
+ 'f' => $args['force_default'] ? 'y' : false,
+ 'r' => $args['rating'],
+ );
+
+ if ( is_ssl() ) {
+ $url = 'https://secure.gravatar.com/avatar/' . $email_hash;
+ } else {
+ $url = sprintf( 'http://%d.gravatar.com/avatar/%s', $gravatar_server, $email_hash );
+ }
+
+ $url = add_query_arg(
+ rawurlencode_deep( array_filter( $url_args ) ),
+ set_url_scheme( $url, $args['scheme'] )
+ );
+
+ /**
+ * Filters the avatar URL.
+ *
+ * @since 4.2.0
+ *
+ * @param string $url The URL of the avatar.
+ * @param mixed $id_or_email The Gravatar to retrieve. Accepts a user_id, gravatar md5 hash,
+ * user email, WP_User object, WP_Post object, or WP_Comment object.
+ * @param array $args Arguments passed to get_avatar_data(), after processing.
+ */
+ $args['url'] = apply_filters( 'get_avatar_url', $url, $id_or_email, $args );
+
+ /**
+ * Filters the avatar data.
+ *
+ * @since 4.2.0
+ *
+ * @param array $args Arguments passed to get_avatar_data(), after processing.
+ * @param mixed $id_or_email The Gravatar to retrieve. Accepts a user_id, gravatar md5 hash,
+ * user email, WP_User object, WP_Post object, or WP_Comment object.
+ */
+ return apply_filters( 'get_avatar_data', $args, $id_or_email );
+}