<?php

/**

 * Post revision functions.

 *

 * @package WordPress

 * @subpackage Post_Revisions

 */

/**

 * Determines which fields of posts are to be saved in revisions.

 *

 * @since 2.6.0

 * @access private

 *

 */

		// Allow these to be versioned

		$fields = array(

			'post_title' => __( 'Title' ),

			'post_content' => __( 'Content' ),

			'post_excerpt' => __( 'Excerpt' ),

		);

	}

}

/**

 * Creates a revision for the current version of a post.

 *

 * Typically used immediately after a post update, as every update is a revision,

 * and the most recent revision always matches the current post.

 *

 * @since 2.6.0

 *

 */

function wp_save_post_revision( $post_id ) {

	if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE )

		return;

	if ( ! $post = get_post( $post_id ) )

		return;

	if ( ! post_type_supports( $post->post_type, 'revisions' ) )

		return;

	if ( 'auto-draft' == $post->post_status )

		return;

	if ( ! wp_revisions_enabled( $post ) )

		return;

	// Compare the proposed update with the last stored revision verifying that

	// they are different, unless a plugin tells us to always save regardless.

	// If no previous revisions, save one

	if ( $revisions = wp_get_post_revisions( $post_id ) ) {

		// grab the last revision, but not an autosave

		foreach ( $revisions as $revision ) {

			if ( false !== strpos( $revision->post_name, "{$revision->post_parent}-revision" ) ) {

				$last_revision = $revision;

				break;

			}

		}

		/**

		 *

		 * By default a revision is saved only if one of the revisioned fields has changed.

		 * This filter can override that so a revision is saved even if nothing has changed.

		 *

		 * @since 3.6.0

		 *

		 * @param bool    $check_for_changes Whether to check for changes before saving a new revision.

		 *                                   Default true.

		 * @param WP_Post $post              The post object.

		 *

		 */

		if ( isset( $last_revision ) && apply_filters( 'wp_save_post_revision_check_for_changes', $check_for_changes = true, $last_revision, $post ) ) {

			$post_has_changed = false;

				if ( normalize_whitespace( $post->$field ) != normalize_whitespace( $last_revision->$field ) ) {

					$post_has_changed = true;

					break;

				}

			}

			/**

			 *

			 * By default a revision is saved only if one of the revisioned fields has changed.

			 * This filter allows for additional checks to determine if there were changes.

			 *

			 * @since 4.1.0

			 *

			 * @param bool    $post_has_changed Whether the post has changed.

			 * @param WP_Post $last_revision    The last revision post object.

			 * @param WP_Post $post             The post object.

			 *

			 */

			$post_has_changed = (bool) apply_filters( 'wp_save_post_revision_post_has_changed', $post_has_changed, $last_revision, $post );

			//don't save revision if post unchanged

				return;

			}

		}

	}

	$return = _wp_put_post_revision( $post );

	// If a limit for the number of revisions to keep has been set,

	// delete the oldest ones.

	$revisions_to_keep = wp_revisions_to_keep( $post );

	if ( $revisions_to_keep < 0 )

		return $return;

	$revisions = wp_get_post_revisions( $post_id, array( 'order' => 'ASC' ) );

	$delete = count($revisions) - $revisions_to_keep;

	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. If the optional $user_id is passed, returns the autosave for that user

 * otherwise returns the latest autosave.

 *

 * @since 2.6.0

 *

 * @param int $post_id The post ID.

 */

function wp_get_post_autosave( $post_id, $user_id = 0 ) {

	$revisions = wp_get_post_revisions( $post_id, array( 'check_enabled' => false ) );

	foreach ( $revisions as $revision ) {

		if ( false !== strpos( $revision->post_name, "{$post_id}-autosave" ) ) {

			if ( $user_id && $user_id != $revision->post_author )

				continue;

			return $revision;

		}

	}

	return false;

}

/**

 * Determines if the specified post is a revision.

 *

 * @since 2.6.0

 *

 */

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.

 *

 * @since 2.6.0

 *

 */

function wp_is_post_autosave( $post ) {

	if ( !$post = wp_get_post_revision( $post ) )

		return false;

	if ( false !== strpos( $post->post_name, "{$post->post_parent}-autosave" ) )

		return (int) $post->post_parent;

	return false;

}

/**

 * Inserts post data into the posts table as a post revision.

 *

 * @since 2.6.0

 * @access private

 *

 */

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']) )

	if ( isset($post['post_type']) && 'revision' == $post['post_type'] )

		return new WP_Error( 'post_type', __( 'Cannot create a revision of a revision' ) );

	$post = wp_slash($post); //since data is from db

	$revision_id = wp_insert_post( $post );

	if ( is_wp_error($revision_id) )

		return $revision_id;

	if ( $revision_id ) {

		/**

		 * Fires once a revision has been saved.

		 *

		 * @since 2.6.0

		 *

		 * @param int $revision_id Post revision ID.

		 */

		do_action( '_wp_put_post_revision', $revision_id );

	}

	return $revision_id;

}

/**

 * Gets a post revision.

 *

 * @since 2.6.0

 *

 */

function wp_get_post_revision(&$post, $output = OBJECT, $filter = 'raw') {

	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.

 *

 * @since 2.6.0

 *

 */

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 ) )

	$update = array();

		$update[$field] = $revision[$field];

	}

	if ( !$update )

		return false;

	$update['ID'] = $revision['post_parent'];

	$update = wp_slash( $update ); //since data is from db

	$post_id = wp_update_post( $update );

	if ( ! $post_id || is_wp_error( $post_id ) )

		return $post_id;

	// Update last edit user

	update_post_meta( $post_id, '_edit_last', get_current_user_id() );

	/**

	 * Fires after a post revision has been restored.

	 *

	 * @since 2.6.0

	 *

	 * @param int $post_id     Post ID.

	 * @param int $revision_id Post revision 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.

 *

 * @since 2.6.0

 *

 */

function wp_delete_post_revision( $revision_id ) {

		return $revision;

	$delete = wp_delete_post( $revision->ID );

	if ( $delete ) {

		/**

		 * Fires once a post revision has been deleted.

		 *

		 * @since 2.6.0

		 *

		 * @param int          $revision_id Post revision ID.

		 * @param object|array $revision    Post revision object or array.

		 */

		do_action( 'wp_delete_post_revision', $revision->ID, $revision );

	}