<?php
/**
 * Article revisions: list, compare and restore.
 *
 * @package KarmaDocs
 */

namespace KarmaDocs\Rest;

use KarmaDocs\PostTypes;

defined( 'ABSPATH' ) || exit;

/**
 * Used by the article drawer's History tab.
 */
class RevisionsController {

	/**
	 * Registers routes.
	 */
	public function routes() {
		$can_edit = static fn( $request ) => current_user_can( 'edit_post', (int) $request['id'] );
		register_rest_route(
			Routes::NS,
			'/articles/(?P<id>\d+)/revisions',
			array(
				'methods'             => 'GET',
				'callback'            => array( $this, 'index' ),
				'permission_callback' => $can_edit,
			)
		);
		register_rest_route(
			Routes::NS,
			'/articles/(?P<id>\d+)/revisions/(?P<revision>\d+)/diff',
			array(
				'methods'             => 'GET',
				'callback'            => array( $this, 'diff' ),
				'args'                => array( 'to' => array( 'type' => 'integer' ) ),
				'permission_callback' => $can_edit,
			)
		);
		register_rest_route(
			Routes::NS,
			'/articles/(?P<id>\d+)/revisions/(?P<revision>\d+)/restore',
			array(
				'methods'             => 'POST',
				'callback'            => array( $this, 'restore' ),
				'permission_callback' => $can_edit,
			)
		);
	}

	/**
	 * The article, or an error.
	 *
	 * @param int $id Id.
	 * @return \WP_Post|\WP_Error
	 */
	private function article( $id ) {
		$post = get_post( (int) $id );
		if ( ! $post || PostTypes::ARTICLE !== $post->post_type ) {
			return new \WP_Error( 'kdocs_not_found', __( 'Article not found.', 'karma-docs' ), array( 'status' => 404 ) );
		}
		return $post;
	}

	/**
	 * A revision of the article (or the article itself for its current state).
	 *
	 * @param \WP_Post $post Article.
	 * @param int      $id   Revision id.
	 * @return \WP_Post|\WP_Error
	 */
	private function revision( $post, $id ) {
		if ( (int) $id === $post->ID ) {
			return $post;
		}
		$revision_id = (int) $id;
		$revision    = wp_get_post_revision( $revision_id );
		if ( ! $revision || (int) $revision->post_parent !== $post->ID ) {
			return new \WP_Error( 'kdocs_not_found', __( 'Revision not found.', 'karma-docs' ), array( 'status' => 404 ) );
		}
		return $revision;
	}

	/**
	 * GET /articles/{id}/revisions.
	 *
	 * @param \WP_REST_Request $request Request.
	 * @return \WP_REST_Response|\WP_Error
	 */
	public function index( $request ) {
		$post = $this->article( $request['id'] );
		if ( is_wp_error( $post ) ) {
			return $post;
		}
		$list = array();
		foreach ( wp_get_post_revisions( $post->ID, array( 'posts_per_page' => 50 ) ) as $revision ) {
			$author = get_userdata( (int) $revision->post_author );
			$list[] = array(
				'id'       => (int) $revision->ID,
				'date'     => strtotime( $revision->post_modified_gmt . ' UTC' ),
				'author'   => $author ? $author->display_name : '',
				'autosave' => wp_is_post_autosave( $revision ) ? true : false,
				'title'    => html_entity_decode( $revision->post_title, ENT_QUOTES, 'UTF-8' ),
			);
		}
		return rest_ensure_response(
			array(
				'current'   => $post->ID,
				'revisions' => $list,
			)
		);
	}

	/**
	 * GET /articles/{id}/revisions/{revision}/diff?to=: side-by-side HTML diff of
	 * title, excerpt and content (to = another revision, default the current article).
	 *
	 * @param \WP_REST_Request $request Request.
	 * @return \WP_REST_Response|\WP_Error
	 */
	public function diff( $request ) {
		$post = $this->article( $request['id'] );
		if ( is_wp_error( $post ) ) {
			return $post;
		}
		$from = $this->revision( $post, $request['revision'] );
		$to   = $this->revision( $post, $request['to'] ? $request['to'] : $post->ID );
		if ( is_wp_error( $from ) || is_wp_error( $to ) ) {
			return is_wp_error( $from ) ? $from : $to;
		}
		$fields = array(
			'post_title'   => __( 'Title', 'karma-docs' ),
			'post_excerpt' => __( 'Excerpt', 'karma-docs' ),
			'post_content' => __( 'Content', 'karma-docs' ),
		);
		$diffs  = array();
		foreach ( $fields as $field => $label ) {
			$html = wp_text_diff(
				self::readable( $from->$field ),
				self::readable( $to->$field ),
				array( 'show_split_view' => true )
			);
			if ( $html ) {
				$diffs[] = array(
					'field' => $label,
					'html'  => $html,
				);
			}
		}
		return rest_ensure_response( array( 'diffs' => $diffs ) );
	}

	/**
	 * Block markup without comment delimiters, one block per line group.
	 *
	 * @param string $text Text.
	 * @return string
	 */
	private static function readable( $text ) {
		$text = preg_replace( '/<!--\s*\/?wp:[^>]*-->\n?/', '', (string) $text );
		return trim( preg_replace( "/\n{3,}/", "\n\n", $text ) );
	}

	/**
	 * POST /articles/{id}/revisions/{revision}/restore.
	 *
	 * @param \WP_REST_Request $request Request.
	 * @return \WP_REST_Response|\WP_Error
	 */
	public function restore( $request ) {
		$post = $this->article( $request['id'] );
		if ( is_wp_error( $post ) ) {
			return $post;
		}
		$revision = $this->revision( $post, $request['revision'] );
		if ( is_wp_error( $revision ) || $revision->ID === $post->ID ) {
			return is_wp_error( $revision ) ? $revision : new \WP_Error( 'kdocs_invalid', __( 'Choose an earlier revision.', 'karma-docs' ), array( 'status' => 400 ) );
		}
		if ( ! wp_restore_post_revision( $revision->ID ) ) {
			return new \WP_Error( 'kdocs_failed', __( 'The revision could not be restored.', 'karma-docs' ), array( 'status' => 500 ) );
		}
		return rest_ensure_response( array( 'restored' => true ) );
	}
}