<?php

/**
* Register custom REST API routes.
 */
add_action(
    'rest_api_init',
    function () {
	// 	Define API endpoint arguments
	        $slug_arg = [
	            'validate_callback' => function ( $param, $request, $key ) {
		return( is_string( $param ) );
	}
	,
	        ];
	$post_slug_arg = array_merge(
	            $slug_arg,
	            [
	                'description' => 'String representing a valid WordPress post slug',
	            ]
	        );
	$page_slug_arg = array_merge(
	            $slug_arg,
	            [
	                'description' => 'String representing a valid WordPress page slug',
	            ]
	        );
	
	// 	Register routes
	        register_rest_route( 'api/v1', '/post', [
	            'methods'  => 'GET',
	            'callback' => 'rest_get_post',
	            'args' => [
	                'slug' => array_merge(
	                    $post_slug_arg,
	                    [
	                        'required' => true,
	                    ]
	                ),
	            ],
	        ] );
	
	register_rest_route( 'api/v1', '/page', [
	            'methods'  => 'GET',
	            'callback' => 'rest_get_page',
	            'args' => [
	                'slug' => array_merge(
	                    $page_slug_arg,
	                    [
	                        'required' => true,
	                    ]
	                ),
	            ],
	        ] );
	
	register_rest_route('api/v1', '/post/preview', [
	            'methods'  => 'GET',
	            'callback' => 'rest_get_post_preview',
	            'args' => [
	                'id' => [
	                    'validate_callback' => function ( $param, $request, $key ) {
		return ( is_numeric( $param ) );
	}
	,
	                    'required' => true,
	                    'description' => 'Valid WordPress post ID',
	                ],
	            ],
	            'permission_callback' => function () {
		return current_user_can( 'edit_posts' );
	}
	,
	        ] );
}
);


/**
* Respond to a REST API request to get post data.
 *
 * @param WP_REST_Request $request Request.
 * @return WP_REST_Response
 */
function rest_get_post( WP_REST_Request $request ) {
	return rest_get_content( $request, 'post', __FUNCTION__ );
}


/**
* Respond to a REST API request to get page data.
 *
 * @param WP_REST_Request $request Request.
 * @return WP_REST_Response
 */
function rest_get_page( WP_REST_Request $request ) {
	return rest_get_content( $request, 'page', __FUNCTION__ );
}


/**
* Respond to a REST API request to get post or page data.
 * * Handles changed slugs
 * * Doesn't return posts whose status isn't published
 * * Redirects to the admin when an edit parameter is present
 *
 * @param WP_REST_Request $request Request
 * @param str             $type Type
 * @param str             $function_name Function name
 * @return WP_REST_Response
 */
function rest_get_content( WP_REST_Request $request, $type, $function_name ) {
	$content_in_array = in_array(
	        $type,
	        [
	            'post',
	            'page',
	        ],
	        true
	    );
	if ( ! $content_in_array ) {
		$type = 'post';
	}
	$slug = $request->get_param( 'slug' );
	$post = get_content_by_slug( $slug, $type );
	if ( ! $post ) {
		return new WP_Error(
		            $function_name,
		            $slug . ' ' . $type . ' does not exist',
		            [
		                'status' => 404,
		            ]
		        );
	}
	;
	
	// 	Shortcut to WP admin page editor
	    $edit = $request->get_param( 'edit' );
	if ( 'true' === $edit ) {
		header( 'Location: /wp-admin/post.php?post=' . $post->ID . '&action=edit' );
		exit;
	}
	$controller = new WP_REST_Posts_Controller( 'post' );
	$data = $controller->prepare_item_for_response( $post, $request );
	$response = $controller->prepare_response_for_collection( $data );
	
	return new WP_REST_Response( $response );
}


/**
* Returns a post or page given a slug. Returns false if no post matches.
 *
 * @param str $slug Slug
 * @param str $type Valid values are 'post' or 'page'
 * @return Post
 */
function get_content_by_slug( $slug, $type = 'post' ) {
	$content_in_array = in_array(
	        $type,
	        [
	            'post',
	            'page',
	        ],
	        true
	    );
	if ( ! $content_in_array ) {
		$type = 'post';
	}
	$args = [
	        'name'        => $slug,
	        'post_type'   => $type,
	        'post_status' => 'publish',
	        'numberposts' => 1,
	    ];
	
	// 	phpcs:ignore WordPress.VIP.RestrictedFunctions.get_posts_get_posts
	    $post_search_results = get_posts( $args );
	
	if ( !$post_search_results ) {
		// 		Maybe the slug changed
		        // 		check wp_postmeta table for old slug
		        $args = [
		            // 		phpcs:ignore WordPress.VIP.SlowDBQuery.slow_db_query_meta_query
		            'meta_query' => [
		                [
		                    'key' => '_wp_old_slug',
		                    'value' => $post_slug,
		                    'compare' => '=',
		                ],
		            ],
		        ];
		$query = new WP_Query( $args );
		$post_search_results = $query->posts;
	}
	if ( isset( $post_search_results[0] ) ) {
		return $post_search_results[0];
	}
	return false;
}


/**
* Respond to a REST API request to get a post's latest revision.
 * * Requires a valid _wpnonce on the query string
 * * User must have 'edit_posts' rights
 * * Will return draft revisions of even published posts
 *
 * @param  WP_REST_Request $request Rest request.
 * @return WP_REST_Response
 */
function rest_get_post_preview( WP_REST_Request $request ) {
    $post_id = $request->get_param( 'id' );
    // Revisions are drafts so here we remove the default 'publish' status
    remove_action( 'pre_get_posts', 'set_default_status_to_publish' );
    $check_enabled = [
        'check_enabled' => false,
    ];
    if ( $revisions = wp_get_post_revisions( $post_id, $check_enabled ) ) {
        $last_revision = reset( $revisions );
        $rev_post = wp_get_post_revision( $last_revision->ID );
        $controller = new WP_REST_Posts_Controller( 'post' );
        $data = $controller->prepare_item_for_response( $rev_post, $request );
    } elseif ( $post = get_post( $post_id ) ) { // There are no revisions, just return the saved parent post
        $controller = new WP_REST_Posts_Controller( 'post' );
        $data = $controller->prepare_item_for_response( $post, $request );
    } else {
        $not_found = [
            'status' => 404,
        ];
        $error = new WP_Error(
            'rest_get_post_preview',
            'Post ' . $post_id . ' does not exist',
            $not_found
        );
        return $error;
    }
    $response = $controller->prepare_response_for_collection( $data );
    return new WP_REST_Response( $response );
}