block-editor-assets-endpoint.php

<?php
/*
 * Plugin Name: Block Editor Assets Endpoint
 * Description: Adds a REST API endpoint for retrieving block editor assets.
 * Version: 0.0.1-alpha.3
 * Author: WordPress Contributors
 * Author URI: https://github.com/WordPress/gutenberg
 * License: GPL-2.0-or-later
 * License URI: https://www.gnu.org/licenses/gpl-2.0.html
 * Requires Plugins: gutenberg
 */

/**
 * REST API: WP_REST_Block_Editor_Assets_Controller class
 *
 * @package WordPress
 * @subpackage REST_API
 */

if ( ! class_exists( 'WP_REST_Block_Editor_Assets_Controller' ) ) {

	/**
	 * Core class used to retrieve the block editor assets via the REST API.
	 *
	 * @see WP_REST_Controller
	 */
	class WP_REST_Block_Editor_Assets_Controller extends WP_REST_Controller {
		/**
		 * Constructor.
		 */
		public function __construct() {
			$this->namespace = '__experimental/wp-block-editor/v1';
			$this->rest_base = 'editor-assets';
		}

		/**
		 * Registers the controller routes.
		 */
		public function register_routes() {
			register_rest_route(
				$this->namespace,
				'/' . $this->rest_base,
				array(
					array(
						'methods'             => WP_REST_Server::READABLE,
						'callback'            => array( $this, 'get_items' ),
						'permission_callback' => array( $this, 'get_items_permissions_check' ),
					),
					'schema' => array( $this, 'get_public_item_schema' ),
				)
			);
		}

		/**
		 * Retrieves a collection of items.
		 *
		 * @param WP_REST_Request $request The request object.
		 *
		 * @return WP_REST_Response|WP_Error Response object on success, or WP_Error object on failure.
		 */
		public function get_items( $request ) { // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable
			global $wp_styles, $wp_scripts;

			$current_wp_styles  = $wp_styles;
			$current_wp_scripts = $wp_scripts;

			$wp_styles  = new WP_Styles();
			$wp_scripts = new WP_Scripts();

			// Trigger an action frequently used by plugins to enqueue assets.
			do_action( 'wp_loaded' );

			// We generally do not need reset styles for the block editor. However, if
			// it's a classic theme, margins will be added to every block, which is
			// reset specifically for list items, so classic themes rely on these
			// reset styles.
			$wp_styles->done =
				wp_theme_has_theme_json() ? array( 'wp-reset-editor-styles' ) : array();

			wp_enqueue_script( 'wp-polyfill' );
			// Enqueue the `editorStyle` handles for all core block, and dependencies.
			wp_enqueue_style( 'wp-edit-blocks' );

			if ( current_theme_supports( 'wp-block-styles' ) ) {
				wp_enqueue_style( 'wp-block-library-theme' );
			}

			// Enqueue frequent dependent, admin-only `dashicon` asset.
			wp_enqueue_style( 'dashicons' );

			// Enqueue the admin-only `postbox` asset required for the block editor.
			$suffix = wp_scripts_get_suffix();
			wp_enqueue_script( 'postbox', "/wp-admin/js/postbox$suffix.js", array( 'jquery-ui-sortable', 'wp-a11y' ), false, 1 );

			// Enqueue foundational post editor assets.
			wp_enqueue_script( 'wp-edit-post' );
			wp_enqueue_style( 'wp-edit-post' );

			// Ensure the block editor scripts and styles are enqueued.
			add_filter( 'should_load_block_editor_scripts_and_styles', '__return_true' );
			do_action( 'enqueue_block_assets' );
			do_action( 'enqueue_block_editor_assets' );
			remove_filter( 'should_load_block_editor_scripts_and_styles', '__return_true' );

			// Additionally, enqueue `editorStyle` and `editorScript` assets for all
			// blocks, which contains editor-only styling for blocks (editor content).
			$block_registry = WP_Block_Type_Registry::get_instance();
			foreach ( $block_registry->get_all_registered() as $block_type ) {
				if ( isset( $block_type->editor_style_handles ) && is_array( $block_type->editor_style_handles ) ) {
					foreach ( $block_type->editor_style_handles as $style_handle ) {
						wp_enqueue_style( $style_handle );
					}
				}
				if ( isset( $block_type->editor_script_handles ) && is_array( $block_type->editor_script_handles ) ) {
					foreach ( $block_type->editor_script_handles as $script_handle ) {
						wp_enqueue_script( $script_handle );
					}
				}
			}

			// Remove the deprecated `print_emoji_styles` handler. It avoids breaking
			// style generation with a deprecation message.
			$has_emoji_styles = has_action( 'wp_print_styles', 'print_emoji_styles' );
			if ( $has_emoji_styles ) {
				remove_action( 'wp_print_styles', 'print_emoji_styles' );
			}

			ob_start();
			wp_print_styles();
			$styles = ob_get_clean();

			if ( $has_emoji_styles ) {
				add_action( 'wp_print_styles', 'print_emoji_styles' );
			}

			ob_start();
			wp_print_head_scripts();
			wp_print_footer_scripts();
			$scripts = ob_get_clean();

			$wp_styles  = $current_wp_styles;
			$wp_scripts = $current_wp_scripts;

			return array(
				'styles'  => $styles,
				'scripts' => $scripts,
			);
		}

		/**
		 * Checks the permissions for retrieving items.
		 *
		 * @param WP_REST_Request $request The REST request object.
		 *
		 * @return bool|WP_Error True if the request has permission, WP_Error object otherwise.
		 */
		public function get_items_permissions_check( $request ) { // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable
			if ( current_user_can( 'edit_posts' ) ) {
				return true;
			}

			foreach ( get_post_types( array( 'show_in_rest' => true ), 'objects' ) as $post_type ) {
				if ( current_user_can( $post_type->cap->edit_posts ) ) {
					return true;
				}
			}

			return new WP_Error(
				'rest_cannot_read_block_editor_assets',
				__( 'Sorry, you are not allowed to read the block editor assets.', 'gutenberg' ),
				array( 'status' => rest_authorization_required_code() )
			);
		}

		/**
		 * Retrieves the block editor assets schema, conforming to JSON Schema.
		 *
		 * @return array Item schema data.
		 */
		public function get_item_schema() {
			if ( $this->schema ) {
				return $this->add_additional_fields_schema( $this->schema );
			}

			$schema = array(
				'type'       => 'object',
				'properties' => array(
					'styles'  => array(
						'description' => esc_html__( 'Style link tags for the block editor.', 'gutenberg' ),
						'type'        => 'string',
					),
					'scripts' => array(
						'description' => esc_html__( 'Script tags for the block editor.', 'gutenberg' ),
						'type'        => 'string',
					),
				),
			);

			$this->schema = $schema;

			return $this->add_additional_fields_schema( $this->schema );
		}
	}
}

/**
  * Registers the block editor assets REST API route.
  */
function gutenberg_register_block_editor_assets() {
	$editor_assets = new WP_REST_Block_Editor_Assets_Controller();
	$editor_assets->register_routes();
}
add_action( 'rest_api_init', 'gutenberg_register_block_editor_assets' );