<?php

/**

 * Post revision functions.

 *

 * @package WordPress

 * @subpackage Post_Revisions

 */

/**

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

 *

 * @since 2.6.0

 * @since 4.5.0 A `WP_Post` object can now be passed to the `$post` parameter.

 * @since 4.5.0 The optional `$autosave` parameter was deprecated and renamed to `$deprecated`.

 * @access private

 *

 * @param array|WP_Post $post       Optional. A post array or a WP_Post object being processed

 *                                  for insertion as a post revision. Default empty array.

 * @param bool          $deprecated Not used.

 */

function _wp_post_revision_fields( $post = array(), $deprecated = false ) {

	static $fields = null;

	if ( ! is_array( $post ) ) {

		$post = get_post( $post, ARRAY_A );

	}

	if ( is_null( $fields ) ) {

		// Allow these to be versioned.

		$fields = array(

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

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

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

		);

	}

	/**

	 * Filters the list of fields saved in post revisions.

	 *

	 * Included by default: 'post_title', 'post_content' and 'post_excerpt'.

	 *

	 * Disallowed fields: 'ID', 'post_name', 'post_parent', 'post_date',

	 * 'post_date_gmt', 'post_status', 'post_type', 'comment_count',

	 * and 'post_author'.

	 *

	 * @since 2.6.0

	 * @since 4.5.0 The `$post` parameter was added.

	 *

	 */

	$fields = apply_filters( '_wp_post_revision_fields', $fields, $post );

	// 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 ] );

	}

	return $fields;

}

/**

 * Returns a post array ready to be inserted into the posts table as a post revision.

 *

 * @since 4.5.0

 * @access private

 *

 * @param array|WP_Post $post     Optional. A post array or a WP_Post object to be processed

 *                                for insertion as a post revision. Default empty array.

 * @param bool          $autosave Optional. Is the revision an autosave? Default false.

 * @return array Post array ready to be inserted as a post revision.

 */

function _wp_post_revision_data( $post = array(), $autosave = false ) {

	if ( ! is_array( $post ) ) {

		$post = get_post( $post, ARRAY_A );

	}

	$fields = _wp_post_revision_fields( $post );

	$revision_data = array();

	foreach ( array_intersect( array_keys( $post ), array_keys( $fields ) ) as $field ) {

		$revision_data[ $field ] = $post[ $field ];

	}

	$revision_data['post_parent']   = $post['ID'];

	$revision_data['post_status']   = 'inherit';

	$revision_data['post_type']     = 'revision';

	$revision_data['post_name']     = $autosave ? "$post[ID]-autosave-v1" : "$post[ID]-revision-v1"; // "1" is the revisioning system version.

	$revision_data['post_date']     = isset( $post['post_modified'] ) ? $post['post_modified'] : '';

	$revision_data['post_date_gmt'] = isset( $post['post_modified_gmt'] ) ? $post['post_modified_gmt'] : '';

	return $revision_data;

}

/**

 * 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

 *

 * @param int $post_id The ID of the post to save as a revision.

 * @return int|WP_Error|void Void or 0 if error, new revision ID, if success.

 */

function wp_save_post_revision( $post_id ) {

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

		return;

	}

	$post = get_post( $post_id );

	if ( ! $post ) {

		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.

	 */

	$revisions = wp_get_post_revisions( $post_id );

	if ( $revisions ) {

		foreach ( $revisions as $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.

		 */

			$post_has_changed = false;

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

					$post_has_changed = true;

					break;

				}

			}

			/**

			 * Filters whether a post has changed.

			 *

			 * 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 $post             The post object.

			 */

			// 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;

	}

	$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++ ) {

			continue;

		}

		wp_delete_post_revision( $revisions[ $i ]->ID );

	}

	return $return;

}

/**

 *

 * Returns a post object with 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

 *

 * @global wpdb $wpdb WordPress database abstraction object.

 *

 * @param int $post_id The post ID.

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

 */

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

	global $wpdb;

	$autosave_name = $post_id . '-autosave-v1';

	$user_id_query = ( 0 !== $user_id ) ? "AND post_author = $user_id" : null;

	// Construct the autosave query.

	$autosave_query = "

		SELECT *

		FROM $wpdb->posts

		WHERE post_parent = %d

		AND post_type = 'revision'

		AND post_status = 'inherit'

		AND post_name   = %s " . $user_id_query . '

		ORDER BY post_date DESC

		LIMIT 1';

	$autosave = $wpdb->get_results(

		$wpdb->prepare(

			$autosave_query,

			$post_id,

			$autosave_name

		)

	);

	if ( ! $autosave ) {

		return false;

	}

	return get_post( $autosave[0] );

}

/**

 * Determines if the specified post is a revision.

 *

 * @since 2.6.0

 *

 * @param int|WP_Post $post Post ID or post object.

 * @return int|false ID of revision's parent on success, false if not a revision.

 */

function wp_is_post_revision( $post ) {

	$post = wp_get_post_revision( $post );

	if ( ! $post ) {

		return false;

	}

	return (int) $post->post_parent;

}

/**

 * Determines if the specified post is an autosave.

 *

 * @since 2.6.0

 *

 * @param int|WP_Post $post Post ID or post object.

 * @return int|false ID of autosave's parent on success, false if not a revision.

 */

function wp_is_post_autosave( $post ) {

	$post = wp_get_post_revision( $post );

	if ( ! $post ) {

		return false;

	}

		return (int) $post->post_parent;

	}

	return false;

}

/**

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

 *

 * @since 2.6.0

 * @access private

 *

 * @param int|WP_Post|array|null $post     Post ID, post object OR post array.

 * @return int|WP_Error WP_Error 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 new WP_Error( 'invalid_post', __( 'Invalid 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_post_revision_data( $post, $autosave );

	$post = wp_slash( $post ); // Since data is from DB.

	$revision_id = wp_insert_post( $post, true );

	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.

		 */

	}

	return $revision_id;

}