+/**
+ * Determines which fields of posts are to be saved in revisions.
+ *
+ * Does two things. If passed a post *array*, it will return a post array ready
+ * to be insterted into the posts table as a post revision. Otherwise, returns
+ * an array whose keys are the post fields to be saved for post revisions.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ * @access private
+ * @uses apply_filters() Calls '_wp_post_revision_fields' on 'title', 'content' and 'excerpt' fields.
+ *
+ * @param array $post Optional a post array to be processed for insertion as a post revision.
+ * @param bool $autosave optional Is the revision an autosave?
+ * @return array Post array ready to be inserted as a post revision or array of fields that can be versioned.
+ */
+function _wp_post_revision_fields( $post = null, $autosave = false ) {
+ static $fields = false;
+
+ if ( !$fields ) {
+ // Allow these to be versioned
+ $fields = array(
+ 'post_title' => __( 'Title' ),
+ 'post_content' => __( 'Content' ),
+ 'post_excerpt' => __( 'Excerpt' ),
+ );
+
+ // Runs only once
+ $fields = apply_filters( '_wp_post_revision_fields', $fields );
+
+ // WP uses these internally either in versioning or elsewhere - they cannot be versioned
+ foreach ( array( 'ID', 'post_name', 'post_parent', 'post_date', 'post_date_gmt', 'post_status', 'post_type', 'comment_count', 'post_author' ) as $protect )
+ unset( $fields[$protect] );
+ }
+
+ if ( !is_array($post) )
+ return $fields;
+
+ $return = array();
+ foreach ( array_intersect( array_keys( $post ), array_keys( $fields ) ) as $field )
+ $return[$field] = $post[$field];
+
+ $return['post_parent'] = $post['ID'];
+ $return['post_status'] = 'inherit';
+ $return['post_type'] = 'revision';
+ $return['post_name'] = $autosave ? "$post[ID]-autosave" : "$post[ID]-revision";
+ $return['post_date'] = isset($post['post_modified']) ? $post['post_modified'] : '';
+ $return['post_date_gmt'] = isset($post['post_modified_gmt']) ? $post['post_modified_gmt'] : '';
+
+ return $return;
+}
+
+/**
+ * Saves an already existing post as a post revision.
+ *
+ * Typically used immediately prior to post updates.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @uses _wp_put_post_revision()
+ *
+ * @param int $post_id The ID of the post to save as a revision.
+ * @return mixed Null or 0 if error, new revision ID, if success.
+ */
+function wp_save_post_revision( $post_id ) {
+ // We do autosaves manually with wp_create_post_autosave()
+ if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE )
+ return;
+
+ // WP_POST_REVISIONS = 0, false
+ if ( !constant('WP_POST_REVISIONS') )
+ return;
+
+ if ( !$post = get_post( $post_id, ARRAY_A ) )
+ return;
+
+ if ( !in_array( $post['post_type'], array( 'post', 'page' ) ) )
+ return;
+
+ $return = _wp_put_post_revision( $post );
+
+ // WP_POST_REVISIONS = true (default), -1
+ if ( !is_numeric( WP_POST_REVISIONS ) || WP_POST_REVISIONS < 0 )
+ return $return;
+
+ // all revisions and (possibly) one autosave
+ $revisions = wp_get_post_revisions( $post_id, array( 'order' => 'ASC' ) );
+
+ // WP_POST_REVISIONS = (int) (# of autasaves to save)
+ $delete = count($revisions) - WP_POST_REVISIONS;
+
+ if ( $delete < 1 )
+ return $return;
+
+ $revisions = array_slice( $revisions, 0, $delete );
+
+ for ( $i = 0; isset($revisions[$i]); $i++ ) {
+ if ( false !== strpos( $revisions[$i]->post_name, 'autosave' ) )
+ continue;
+ wp_delete_post_revision( $revisions[$i]->ID );
+ }
+
+ return $return;
+}
+
+/**
+ * Retrieve the autosaved data of the specified post.
+ *
+ * Returns a post object containing the information that was autosaved for the
+ * specified post.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @param int $post_id The post ID.
+ * @return object|bool The autosaved data or false on failure or when no autosave exists.
+ */
+function wp_get_post_autosave( $post_id ) {
+
+ if ( !$post = get_post( $post_id ) )
+ return false;
+
+ $q = array(
+ 'name' => "{$post->ID}-autosave",
+ 'post_parent' => $post->ID,
+ 'post_type' => 'revision',
+ 'post_status' => 'inherit'
+ );
+
+ // Use WP_Query so that the result gets cached
+ $autosave_query = new WP_Query;
+
+ add_action( 'parse_query', '_wp_get_post_autosave_hack' );
+ $autosave = $autosave_query->query( $q );
+ remove_action( 'parse_query', '_wp_get_post_autosave_hack' );
+
+ if ( $autosave && is_array($autosave) && is_object($autosave[0]) )
+ return $autosave[0];
+
+ return false;
+}
+
+/**
+ * Internally used to hack WP_Query into submission.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @param object $query WP_Query object
+ */
+function _wp_get_post_autosave_hack( $query ) {
+ $query->is_single = false;
+}
+
+/**
+ * Determines if the specified post is a revision.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @param int|object $post Post ID or post object.
+ * @return bool|int False if not a revision, ID of revision's parent otherwise.
+ */
+function wp_is_post_revision( $post ) {
+ if ( !$post = wp_get_post_revision( $post ) )
+ return false;
+ return (int) $post->post_parent;
+}
+
+/**
+ * Determines if the specified post is an autosave.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @param int|object $post Post ID or post object.
+ * @return bool|int False if not a revision, ID of autosave's parent otherwise
+ */
+function wp_is_post_autosave( $post ) {
+ if ( !$post = wp_get_post_revision( $post ) )
+ return false;
+ if ( "{$post->post_parent}-autosave" !== $post->post_name )
+ return false;
+ return (int) $post->post_parent;
+}
+
+/**
+ * Inserts post data into the posts table as a post revision.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @uses wp_insert_post()
+ *
+ * @param int|object|array $post Post ID, post object OR post array.
+ * @param bool $autosave Optional. Is the revision an autosave?
+ * @return mixed Null or 0 if error, new revision ID if success.
+ */
+function _wp_put_post_revision( $post = null, $autosave = false ) {
+ if ( is_object($post) )
+ $post = get_object_vars( $post );
+ elseif ( !is_array($post) )
+ $post = get_post($post, ARRAY_A);
+ if ( !$post || empty($post['ID']) )
+ return;
+
+ if ( isset($post['post_type']) && 'revision' == $post['post_type'] )
+ return new WP_Error( 'post_type', __( 'Cannot create a revision of a revision' ) );
+
+ $post = _wp_post_revision_fields( $post, $autosave );
+ $post = add_magic_quotes($post); //since data is from db
+
+ $revision_id = wp_insert_post( $post );
+ if ( is_wp_error($revision_id) )
+ return $revision_id;
+
+ if ( $revision_id )
+ do_action( '_wp_put_post_revision', $revision_id );
+ return $revision_id;
+}
+
+/**
+ * Gets a post revision.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @uses get_post()
+ *
+ * @param int|object $post Post ID or post object
+ * @param string $output Optional. OBJECT, ARRAY_A, or ARRAY_N.
+ * @param string $filter Optional sanitation filter. @see sanitize_post()
+ * @return mixed Null if error or post object if success
+ */
+function &wp_get_post_revision(&$post, $output = OBJECT, $filter = 'raw') {
+ $null = null;
+ if ( !$revision = get_post( $post, OBJECT, $filter ) )
+ return $revision;
+ if ( 'revision' !== $revision->post_type )
+ return $null;
+
+ if ( $output == OBJECT ) {
+ return $revision;
+ } elseif ( $output == ARRAY_A ) {
+ $_revision = get_object_vars($revision);
+ return $_revision;
+ } elseif ( $output == ARRAY_N ) {
+ $_revision = array_values(get_object_vars($revision));
+ return $_revision;
+ }
+
+ return $revision;
+}
+
+/**
+ * Restores a post to the specified revision.
+ *
+ * Can restore a past revision using all fields of the post revision, or only selected fields.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @uses wp_get_post_revision()
+ * @uses wp_update_post()
+ * @uses do_action() Calls 'wp_restore_post_revision' on post ID and revision ID if wp_update_post()
+ * is successful.
+ *
+ * @param int|object $revision_id Revision ID or revision object.
+ * @param array $fields Optional. What fields to restore from. Defaults to all.
+ * @return mixed Null if error, false if no fields to restore, (int) post ID if success.
+ */
+function wp_restore_post_revision( $revision_id, $fields = null ) {
+ if ( !$revision = wp_get_post_revision( $revision_id, ARRAY_A ) )
+ return $revision;
+
+ if ( !is_array( $fields ) )
+ $fields = array_keys( _wp_post_revision_fields() );
+
+ $update = array();
+ foreach( array_intersect( array_keys( $revision ), $fields ) as $field )
+ $update[$field] = $revision[$field];
+
+ if ( !$update )
+ return false;
+
+ $update['ID'] = $revision['post_parent'];
+
+ $update = add_magic_quotes( $update ); //since data is from db
+
+ $post_id = wp_update_post( $update );
+ if ( is_wp_error( $post_id ) )
+ return $post_id;
+
+ if ( $post_id )
+ do_action( 'wp_restore_post_revision', $post_id, $revision['ID'] );
+
+ return $post_id;
+}
+
+/**
+ * Deletes a revision.
+ *
+ * Deletes the row from the posts table corresponding to the specified revision.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @uses wp_get_post_revision()
+ * @uses wp_delete_post()
+ *
+ * @param int|object $revision_id Revision ID or revision object.
+ * @param array $fields Optional. What fields to restore from. Defaults to all.
+ * @return mixed Null if error, false if no fields to restore, (int) post ID if success.
+ */
+function wp_delete_post_revision( $revision_id ) {
+ if ( !$revision = wp_get_post_revision( $revision_id ) )
+ return $revision;
+
+ $delete = wp_delete_post( $revision->ID );
+ if ( is_wp_error( $delete ) )
+ return $delete;
+
+ if ( $delete )
+ do_action( 'wp_delete_post_revision', $revision->ID, $revision );
+
+ return $delete;
+}
+
+/**
+ * Returns all revisions of specified post.
+ *
+ * @package WordPress
+ * @subpackage Post_Revisions
+ * @since 2.6.0
+ *
+ * @uses get_children()
+ *
+ * @param int|object $post_id Post ID or post object
+ * @return array empty if no revisions
+ */
+function wp_get_post_revisions( $post_id = 0, $args = null ) {
+ if ( !constant('WP_POST_REVISIONS') )
+ return array();
+ if ( ( !$post = get_post( $post_id ) ) || empty( $post->ID ) )
+ return array();
+
+ $defaults = array( 'order' => 'DESC', 'orderby' => 'date' );
+ $args = wp_parse_args( $args, $defaults );
+ $args = array_merge( $args, array( 'post_parent' => $post->ID, 'post_type' => 'revision', 'post_status' => 'inherit' ) );
+
+ if ( !$revisions = get_children( $args ) )
+ return array();
+ return $revisions;
+}
+
+function _set_preview($post) {
+
+ if ( ! is_object($post) )
+ return $post;
+
+ $preview = wp_get_post_autosave($post->ID);
+
+ if ( ! is_object($preview) )
+ return $post;
+
+ $preview = sanitize_post($preview);
+
+ $post->post_content = $preview->post_content;
+ $post->post_title = $preview->post_title;
+ $post->post_excerpt = $preview->post_excerpt;
+
+ return $post;
+}
+
+function _show_post_preview() {
+
+ if ( isset($_GET['preview_id']) && isset($_GET['preview_nonce']) ) {
+ $id = (int) $_GET['preview_id'];
+
+ if ( false == wp_verify_nonce( $_GET['preview_nonce'], 'post_preview_' . $id ) )
+ wp_die( __('You do not have permission to preview drafts.') );
+
+ add_filter('the_preview', '_set_preview');
+ }
+}