<?php

/**

 * WordPress Administration Revisions API

 *

 * @package WordPress

 * @subpackage Administration

 */

/**

 * Get the revision UI diff.

 *

 * @since 3.6.0

 *

 * @param object|int $post         The post object. Also accepts a post ID.

 * @param int        $compare_from The revision ID to compare from.

 * @param int        $compare_to   The revision ID to come to.

 *

 * @return array|bool Associative array of a post's revisioned fields and their diffs.

 *                    Or, false on failure.

 */

function wp_get_revision_ui_diff( $post, $compare_from, $compare_to ) {

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

		return false;

	if ( $compare_from ) {

		if ( ! $compare_from = get_post( $compare_from ) )

			return false;

	} else {

		// If we're dealing with the first revision...

		$compare_from = false;

	}

	if ( ! $compare_to = get_post( $compare_to ) )

		return false;

	// If comparing revisions, make sure we're dealing with the right post parent.

	// The parent post may be a 'revision' when revisions are disabled and we're looking at autosaves.

	if ( $compare_from && $compare_from->post_parent !== $post->ID && $compare_from->ID !== $post->ID )

		return false;

	if ( $compare_to->post_parent !== $post->ID && $compare_to->ID !== $post->ID )

		return false;

	if ( $compare_from && strtotime( $compare_from->post_date_gmt ) > strtotime( $compare_to->post_date_gmt ) ) {

		$temp = $compare_from;

		$compare_from = $compare_to;

		$compare_to = $temp;

	}

	// Add default title if title field is empty

	if ( $compare_from && empty( $compare_from->post_title ) )

		$compare_from->post_title = __( '(no title)' );

	if ( empty( $compare_to->post_title ) )

		$compare_to->post_title = __( '(no title)' );

	$return = array();

	foreach ( _wp_post_revision_fields() as $field => $name ) {

		/**

		 * Contextually filter a post revision field.

		 *

		 * The dynamic portion of the hook name, $field, corresponds to each of the post

		 * fields of the revision object being iterated over in a foreach statement.

		 *

		 * @since 3.6.0

		 *

		 * @param string  $compare_from->$field The current revision field to compare to or from.

		 * @param string  $field                The current revision field.

		 * @param WP_Post $compare_from         The revision post object to compare to or from.

		 * @param string  null                  The context of whether the current revision is the old or the new one. Values are 'to' or 'from'.

		 */

		$content_from = $compare_from ? apply_filters( "_wp_post_revision_field_$field", $compare_from->$field, $field, $compare_from, 'from' ) : '';

		/** This filter is documented in wp-admin/includes/revision.php */

		$content_to = apply_filters( "_wp_post_revision_field_$field", $compare_to->$field, $field, $compare_to, 'to' );

		$diff = wp_text_diff( $content_from, $content_to, array( 'show_split_view' => true ) );

		if ( ! $diff && 'post_title' === $field ) {

			// It's a better user experience to still show the Title, even if it didn't change.

			// No, you didn't see this.

			$diff = '<table class="diff"><colgroup><col class="content diffsplit left"><col class="content diffsplit middle"><col class="content diffsplit right"></colgroup><tbody><tr>';

			$diff .= '<td>' . esc_html( $compare_from->post_title ) . '</td><td></td><td>' . esc_html( $compare_to->post_title ) . '</td>';

			$diff .= '</tr></tbody>';

			$diff .= '</table>';

		}

		if ( $diff ) {

			$return[] = array(

				'id' => $field,

				'name' => $name,

				'diff' => $diff,

			);

		}

	}

	return $return;

}

/**

 * Prepare revisions for JavaScript.

 *

 * @since 3.6.0

 *

 * @param object|int $post                 The post object. Also accepts a post ID.

 * @param int        $selected_revision_id The selected revision ID.

 * @param int        $from                 Optional. The revision ID to compare from.

 *

 * @return array An associative array of revision data and related settings.

 */

function wp_prepare_revisions_for_js( $post, $selected_revision_id, $from = null ) {

	$post = get_post( $post );

	$revisions = $authors = array();

	$now_gmt = time();

	$revisions = wp_get_post_revisions( $post->ID, array( 'order' => 'ASC', 'check_enabled' => false ) );

	// If revisions are disabled, we only want autosaves and the current post.

	if ( ! wp_revisions_enabled( $post ) ) {

		foreach ( $revisions as $revision_id => $revision ) {

			if ( ! wp_is_post_autosave( $revision ) )

				unset( $revisions[ $revision_id ] );

		}

		$revisions = array( $post->ID => $post ) + $revisions;

	}

	$show_avatars = get_option( 'show_avatars' );

	cache_users( wp_list_pluck( $revisions, 'post_author' ) );

	$can_restore = current_user_can( 'edit_post', $post->ID );

	foreach ( $revisions as $revision ) {

		$modified = strtotime( $revision->post_modified );

		$modified_gmt = strtotime( $revision->post_modified_gmt );

		if ( $can_restore ) {

			$restore_link = str_replace( '&', '&', wp_nonce_url(

				add_query_arg(

					array( 'revision' => $revision->ID,

						'action' => 'restore' ),

						admin_url( 'revision.php' )

				),

				"restore-post_{$revision->ID}"

			) );

		}

		if ( ! isset( $authors[ $revision->post_author ] ) ) {

			$authors[ $revision->post_author ] = array(

				'id' => (int) $revision->post_author,

				'avatar' => $show_avatars ? get_avatar( $revision->post_author, 32 ) : '',

				'name' => get_the_author_meta( 'display_name', $revision->post_author ),

			);

		}

		$autosave = (bool) wp_is_post_autosave( $revision );

		$current = ! $autosave && $revision->post_modified_gmt === $post->post_modified_gmt;

		if ( $current && ! empty( $current_id ) ) {

			// If multiple revisions have the same post_modified_gmt, highest ID is current.

			if ( $current_id < $revision->ID ) {

				$revisions[ $current_id ]['current'] = false;

				$current_id = $revision->ID;

			} else {

				$current = false;

			}

		} elseif ( $current ) {

			$current_id = $revision->ID;

		}

		$revisions[ $revision->ID ] = array(

			'id'         => $revision->ID,

			'title'      => get_the_title( $post->ID ),

			'author'     => $authors[ $revision->post_author ],

			'date'       => date_i18n( __( 'M j, Y @ G:i' ), $modified ),

			'dateShort'  => date_i18n( _x( 'j M @ G:i', 'revision date short format' ), $modified ),

			'timeAgo'    => sprintf( __( '%s ago' ), human_time_diff( $modified_gmt, $now_gmt ) ),

			'autosave'   => $autosave,

			'current'    => $current,

			'restoreUrl' => $can_restore ? $restore_link : false,

		);

	}

	// If a post has been saved since the last revision (no revisioned fields were changed)

	// we may not have a "current" revision. Mark the latest revision as "current".

	if ( empty( $current_id ) ) {

		if ( $revisions[ $revision->ID ]['autosave'] ) {

			$revision = end( $revisions );

			while ( $revision['autosave'] ) {

				$revision = prev( $revisions );

			}

			$current_id = $revision['id'];

		} else {

			$current_id = $revision->ID;

		}

		$revisions[ $current_id ]['current'] = true;

	}

	// Now, grab the initial diff

	$compare_two_mode = is_numeric( $from );

	if ( ! $compare_two_mode ) {

		$found = array_search( $selected_revision_id, array_keys( $revisions ) );

		if ( $found ) {

			$from = array_keys( array_slice( $revisions, $found - 1, 1, true ) );

			$from = reset( $from );

		} else {

			$from = 0;

		}

	}

	$from = absint( $from );

	$diffs = array( array(

		'id' => $from . ':' . $selected_revision_id,

		'fields' => wp_get_revision_ui_diff( $post->ID, $from, $selected_revision_id ),

	));

	return array(

		'postId'           => $post->ID,

		'nonce'            => wp_create_nonce( 'revisions-ajax-nonce' ),

		'revisionData'     => array_values( $revisions ),

		'to'               => $selected_revision_id,

		'from'             => $from,

		'diffData'         => $diffs,

		'baseUrl'          => parse_url( admin_url( 'revision.php' ), PHP_URL_PATH ),

		'compareTwoMode'   => absint( $compare_two_mode ), // Apparently booleans are not allowed

		'revisionIds'      => array_keys( $revisions ),

	);

}