<?php

/**

 * Post revision functions.

 *

 * @package WordPress

 * @subpackage Post_Revisions

 */

/**

 * 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 inserted into the posts table as a post revision. Otherwise, returns

 * an array whose keys are the post fields to be saved for 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-v1" : "$post[ID]-revision-v1"; // "1" is the revisioning system version

	$return['post_date']     = isset($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 after post updates.

 * Adds a copy of the current post as a revision, so latest revision always matches current post

 *

 * @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 ) {

	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;

			}

		}

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

			$post_has_changed = false;

			foreach ( array_keys( _wp_post_revision_fields() ) as $field ) {

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

					$post_has_changed = true;

					break;

				}

			}

			//don't save revision if post unchanged

			if( ! $post_has_changed )

				return;

		}

	}

	$return = _wp_put_post_revision( $post );

	$revisions_to_keep = wp_revisions_to_keep( $post );

	if ( $revisions_to_keep < 0 )

		return $return;

	// all revisions and autosaves

	$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

 *

 * @uses wp_get_post_revisions()

 *

 * @param int $post_id The post ID.

 * @param int $user_id optional The post author ID.

 * @return object|bool The autosaved data or false on failure or when no autosave exists.

 */

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;

			break;

		}

	}

	return false;

}

/**

 * Determines if the specified post is a revision.

 *

 * @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.

 *

 * @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 ( 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

 *

 * @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_id = $post['ID'];

	$post = _wp_post_revision_fields( $post, $autosave );

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

	$revision_id = wp_insert_post( $post );

	if ( is_wp_error($revision_id) )

		return $revision_id;

	if ( $revision_id )

		do_action( '_wp_put_post_revision', $revision_id );

	return $revision_id;

}

/**

 * Gets a post revision.

 *

 * @since 2.6.0

 *

 * @uses get_post()

 *

 * @param int|object $post The post ID or 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.

 *

 * @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 = 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;

	// Add restore from details

	$restore_details = array(

		'restored_revision_id' => $revision_id,

		'restored_by_user'     => get_current_user_id(),

		'restored_time'        => time()

	);

	update_post_meta( $post_id, '_post_restored_from', $restore_details );

	// Update last edit user

	update_post_meta( $post_id, '_edit_last', get_current_user_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

 *

 * @uses wp_get_post_revision()

 * @uses wp_delete_post()

 *

 * @param int|object $revision_id Revision ID or revision object.

 * @return mixed Null or WP_Error if error, deleted post 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.

 *

 * @since 2.6.0

 *

 * @uses get_children()

 *

 * @param int|object $post_id Post ID or post object

 * @return array An array of revisions, or an empty array if none.

 */

function wp_get_post_revisions( $post_id = 0, $args = null ) {

	$post = get_post( $post_id );

	if ( ! $post || empty( $post->ID ) )

		return array();

	$defaults = array( 'order' => 'DESC', 'orderby' => 'date', 'check_enabled' => true );

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

	if ( $args['check_enabled'] && ! wp_revisions_enabled( $post ) )

		return array();

	$args = array_merge( $args, array( 'post_parent' => $post->ID, 'post_type' => 'revision', 'post_status' => 'inherit' ) );

	if ( ! $revisions = get_children( $args ) )

		return array();

	return $revisions;

}

/**

 * Determine if revisions are enabled for a given post.

 *

 * @since 3.6.0

 *

 * @uses wp_revisions_to_keep()

 *

 * @param object $post The post object.

 * @return bool True if number of revisions to keep isn't zero, false otherwise.

 */

function wp_revisions_enabled( $post ) {

	return wp_revisions_to_keep( $post ) != 0;

}

/**

 * Determine how many revisions to retain for a given post.

 * By default, an infinite number of revisions are stored if a post type supports revisions.

 *

 * @since 3.6.0

 *

 * @uses post_type_supports()

 * @uses apply_filters() Calls 'wp_revisions_to_keep' hook on the number of revisions.

 *

 * @param object $post The post object.

 * @return int The number of revisions to keep.

 */

function wp_revisions_to_keep( $post ) {

	$num = WP_POST_REVISIONS;

	if ( true === $num )

		$num = -1;

	else

		$num = intval( $num );

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

		$num = 0;

	return (int) apply_filters( 'wp_revisions_to_keep', $num, $post );

}

/**

 * Sets up the post object for preview based on the post autosave.

 *

 * @since 2.7.0

 * @access private