Try Legacy widget block

gutenberg.php

@@ -46,6 +46,21 @@ function the_gutenberg_project() {
 		<div id="metaboxes" class="hidden">
 			<?php the_block_editor_meta_boxes(); ?>
 		</div>
+		<?php
+		/**
+		 * Start: Include for phase 2
+		 */
+		/** This action is documented in wp-admin/admin-footer.php */
+		// phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores
+		do_action( 'admin_print_footer_scripts-widgets.php' );
+
+		/** This action is documented in wp-admin/admin-footer.php */
+		// phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores
+		do_action( 'admin_footer-widgets.php' );
+		/**
+		 * End: Include for phase 2
+		 */
+		?>
 	</div>
 	<?php
 }
@@ -223,6 +238,17 @@ function gutenberg_init( $return, $post ) {
 	 */
 	remove_action( 'admin_print_scripts', 'print_emoji_detection_script' );
 
+	/**
+	 * Start: Include for phase 2
+	 */
+	// phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores
+	do_action( 'admin_print_styles-widgets.php' );
+	// phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores
+	do_action( 'admin_print_scripts-widgets.php' );
+	/**
+	 * End: Include for phase 2
+	 */
+
 	/*
 	 * Ensure meta box functions are available to third-party code;
 	 * includes/meta-boxes is typically loaded from edit-form-advanced.php.

lib/class-wp-rest-widget-updater-controller.php

@@ -0,0 +1,186 @@
+<?php
+/**
+ * Start: Include for phase 2
+ * Widget Updater REST API: WP_REST_Widget_Updater_Controller class
+ *
+ * @package gutenberg
+ * @since 5.2.0
+ */
+
+/**
+ * Controller which provides REST endpoint for updating a widget.
+ *
+ * @since 5.2.0
+ *
+ * @see WP_REST_Controller
+ */
+class WP_REST_Widget_Updater_Controller extends WP_REST_Controller {
+
+	/**
+	 * Constructs the controller.
+	 *
+	 * @access public
+	 */
+	public function __construct() {
+		$this->namespace = 'wp/v2';
+		$this->rest_base = 'widgets';
+	}
+
+	/**
+	 * Registers the necessary REST API route.
+	 *
+	 * @access public
+	 */
+	public function register_routes() {
+			register_rest_route(
+				$this->namespace,
+				// Regex representing a PHP class extracted from http://php.net/manual/en/language.oop5.basic.php.
+				'/' . $this->rest_base . '/(?P<identifier>[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)/',
+				array(
+					'args' => array(
+						'identifier' => array(
+							'description' => __( 'Class name of the widget.', 'gutenberg' ),
+							'type'        => 'string',
+						),
+					),
+					array(
+						'methods'             => WP_REST_Server::EDITABLE,
+						'permission_callback' => array( $this, 'compute_new_widget_permissions_check' ),
+						'callback'            => array( $this, 'compute_new_widget' ),
+					),
+				)
+			);
+	}
+
+	/**
+	 * Checks if the user has permissions to make the request.
+	 *
+	 * @since 5.2.0
+	 * @access public
+	 *
+	 * @return true|WP_Error True if the request has read access, WP_Error object otherwise.
+	 */
+	public function compute_new_widget_permissions_check() {
+		// Verify if the current user has edit_theme_options capability.
+		// This capability is required to access the widgets screen.
+		if ( ! current_user_can( 'edit_theme_options' ) ) {
+			return new WP_Error(
+				'widgets_cannot_access',
+				__( 'Sorry, you are not allowed to access widgets on this site.', 'gutenberg' ),
+				array(
+					'status' => rest_authorization_required_code(),
+				)
+			);
+		}
+		return true;
+	}
+
+	/**
+	 * Returns the new widget instance and the form that represents it.
+	 *
+	 * @since 5.2.0
+	 * @access public
+	 *
+	 * @param WP_REST_Request $request Full details about the request.
+	 * @return WP_REST_Response|WP_Error Response object on success, or WP_Error object on failure.
+	 */
+	public function compute_new_widget( $request ) {
+		$url_params = $request->get_url_params();
+
+		$widget = $request->get_param( 'identifier' );
+
+		global $wp_widget_factory;
+
+		if (
+			null === $widget ||
+			! isset( $wp_widget_factory->widgets[ $widget ] ) ||
+			! ( $wp_widget_factory->widgets[ $widget ] instanceof WP_Widget )
+		) {
+			return new WP_Error(
+				'widget_invalid',
+				__( 'Invalid widget.', 'gutenberg' ),
+				array(
+					'status' => 404,
+				)
+			);
+		}
+
+		$widget_obj = $wp_widget_factory->widgets[ $widget ];
+
+		$instance = $request->get_param( 'instance' );
+		if ( null === $instance ) {
+			$instance = array();
+		}
+		$id_to_use = $request->get_param( 'id_to_use' );
+		if ( null === $id_to_use ) {
+			$id_to_use = -1;
+		}
+
+		$widget_obj->_set( $id_to_use );
+		ob_start();
+
+		$instance_changes = $request->get_param( 'instance_changes' );
+		if ( null !== $instance_changes ) {
+			$old_instance = $instance;
+			$instance     = $widget_obj->update( $instance_changes, $old_instance );
+			/**
+			 * Filters a widget's settings before saving.
+			 *
+			 * Returning false will effectively short-circuit the widget's ability
+			 * to update settings. The old setting will be returned.
+			 *
+			 * @since 5.2.0
+			 *
+			 * @param array     $instance         The current widget instance's settings.
+			 * @param array     $instance_changes Array of new widget settings.
+			 * @param array     $old_instance     Array of old widget settings.
+			 * @param WP_Widget $widget_ob        The widget instance.
+			 */
+			$instance = apply_filters( 'widget_update_callback', $instance, $instance_changes, $old_instance, $widget_obj );
+			if ( false === $instance ) {
+				$instance = $old_instance;
+			}
+		}
+
+		$instance = apply_filters( 'widget_form_callback', $instance, $widget_obj );
+
+		$return = null;
+		if ( false !== $instance ) {
+			$return = $widget_obj->form( $instance );
+
+			/**
+			 * Fires at the end of the widget control form.
+			 *
+			 * Use this hook to add extra fields to the widget form. The hook
+			 * is only fired if the value passed to the 'widget_form_callback'
+			 * hook is not false.
+			 *
+			 * Note: If the widget has no form, the text echoed from the default
+			 * form method can be hidden using CSS.
+			 *
+			 * @since 5.2.0
+			 *
+			 * @param WP_Widget $widget_obj     The widget instance (passed by reference).
+			 * @param null      $return   Return null if new fields are added.
+			 * @param array     $instance An array of the widget's settings.
+			 */
+			do_action_ref_array( 'in_widget_form', array( &$widget_obj, &$return, $instance ) );
+		}
+
+		$id_base = $widget_obj->id_base;
+		$id      = $widget_obj->id;
+		$form    = ob_get_clean();
+
+		return rest_ensure_response(
+			array(
+				'instance' => $instance,
+				'form'     => $form,
+				'id_base'  => $id_base,
+				'id'       => $id,
+			)
+		);
+	}
+}
+/**
+ * End: Include for phase 2
+ */

lib/client-assets.php

@@ -872,34 +872,83 @@ function gutenberg_editor_scripts_and_styles( $hook ) {
 		);
 	}
 
+	/**
+	 * Start: Include for phase 2
+	 */
+
+	/**
+	 * Todo: The hardcoded array should be replaced with a mechanisms that allows core blocks
+	 * and third party blocks to specify they already have equivalent blocks, and maybe even allow them
+	 * to have a migration function.
+	 */
+	$core_widgets = array( 'WP_Widget_Pages', 'WP_Widget_Calendar', 'WP_Widget_Archives', 'WP_Widget_Media_Audio', 'WP_Widget_Media_Image', 'WP_Widget_Media_Gallery', 'WP_Widget_Media_Video', 'WP_Widget_Meta', 'WP_Widget_Search', 'WP_Widget_Text', 'WP_Widget_Categories', 'WP_Widget_Recent_Posts', 'WP_Widget_Recent_Comments', 'WP_Widget_RSS', 'WP_Widget_Tag_Cloud', 'WP_Nav_Menu_Widget', 'WP_Widget_Custom_HTML' );
+
+	$has_permissions_to_manage_widgets = current_user_can( 'edit_theme_options' );
+	$available_legacy_widgets          = array();
+	global $wp_widget_factory, $wp_registered_widgets;
+	foreach ( $wp_widget_factory->widgets as $class => $widget_obj ) {
+		if ( ! in_array( $class, $core_widgets ) ) {
+			$available_legacy_widgets[ $class ] = array(
+				'name'             => html_entity_decode( $widget_obj->name ),
+				'description'      => html_entity_decode( $widget_obj->widget_options['description'] ),
+				'isCallbackWidget' => false,
+			);
+		}
+	}
+	foreach ( $wp_registered_widgets as $widget_id => $widget_obj ) {
+		if (
+			is_array( $widget_obj['callback'] ) &&
+			isset( $widget_obj['callback'][0] ) &&
+			( $widget_obj['callback'][0] instanceof WP_Widget )
+		) {
+			continue;
+		}
+		$available_legacy_widgets[ $widget_id ] = array(
+			'name'             => html_entity_decode( $widget_obj['name'] ),
+			'description'      => null,
+			'isCallbackWidget' => true,
+		);
+	}
+	/**
+	 * End: Include for phase 2
+	 */
+
 	$editor_settings = array(
-		'alignWide'              => $align_wide,
-		'availableTemplates'     => $available_templates,
-		'allowedBlockTypes'      => $allowed_block_types,
-		'disableCustomColors'    => get_theme_support( 'disable-custom-colors' ),
-		'disableCustomFontSizes' => get_theme_support( 'disable-custom-font-sizes' ),
-		'disablePostFormats'     => ! current_theme_supports( 'post-formats' ),
-		'titlePlaceholder'       => apply_filters( 'enter_title_here', __( 'Add title', 'gutenberg' ), $post ),
-		'bodyPlaceholder'        => apply_filters( 'write_your_story', __( 'Start writing or type / to choose a block', 'gutenberg' ), $post ),
-		'isRTL'                  => is_rtl(),
-		'autosaveInterval'       => 10,
-		'maxUploadFileSize'      => $max_upload_size,
-		'allowedMimeTypes'       => get_allowed_mime_types(),
-		'styles'                 => $styles,
-		'imageSizes'             => gutenberg_get_available_image_sizes(),
-		'richEditingEnabled'     => user_can_richedit(),
+		'alignWide'                     => $align_wide,
+		'availableTemplates'            => $available_templates,
+		/**
+		* Start: Include for phase 2
+		*/
+		'hasPermissionsToManageWidgets' => $has_permissions_to_manage_widgets,
+		'availableLegacyWidgets'        => $available_legacy_widgets,
+		/**
+		* End: Include for phase 2
+		*/
+		'allowedBlockTypes'             => $allowed_block_types,
+		'disableCustomColors'           => get_theme_support( 'disable-custom-colors' ),
+		'disableCustomFontSizes'        => get_theme_support( 'disable-custom-font-sizes' ),
+		'disablePostFormats'            => ! current_theme_supports( 'post-formats' ),
+		'titlePlaceholder'              => apply_filters( 'enter_title_here', __( 'Add title', 'gutenberg' ), $post ),
+		'bodyPlaceholder'               => apply_filters( 'write_your_story', __( 'Start writing or type / to choose a block', 'gutenberg' ), $post ),
+		'isRTL'                         => is_rtl(),
+		'autosaveInterval'              => 10,
+		'maxUploadFileSize'             => $max_upload_size,
+		'allowedMimeTypes'              => get_allowed_mime_types(),
+		'styles'                        => $styles,
+		'imageSizes'                    => gutenberg_get_available_image_sizes(),
+		'richEditingEnabled'            => user_can_richedit(),
 
 		// Ideally, we'd remove this and rely on a REST API endpoint.
-		'postLock'               => $lock_details,
-		'postLockUtils'          => array(
+		'postLock'                      => $lock_details,
+		'postLockUtils'                 => array(
 			'nonce'       => wp_create_nonce( 'lock-post_' . $post->ID ),
 			'unlockNonce' => wp_create_nonce( 'update-post_' . $post->ID ),
 			'ajaxUrl'     => admin_url( 'admin-ajax.php' ),
 		),
 
 		// Whether or not to load the 'postcustom' meta box is stored as a user meta
 		// field so that we're not always loading its assets.
-		'enableCustomFields'     => (bool) get_user_meta( get_current_user_id(), 'enable_custom_fields', true ),
+		'enableCustomFields'            => (bool) get_user_meta( get_current_user_id(), 'enable_custom_fields', true ),
 	);
 
 	$post_autosave = gutenberg_get_autosave_newer_than_post_save( $post );

lib/load.php

@@ -12,6 +12,15 @@
 // These files only need to be loaded if within a rest server instance
 // which this class will exist if that is the case.
 if ( class_exists( 'WP_REST_Controller' ) ) {
+	/**
+	* Start: Include for phase 2
+	*/
+	if ( ! class_exists( 'WP_REST_Widget_Updater_Controller' ) ) {
+		require dirname( __FILE__ ) . '/class-wp-rest-widget-updater-controller.php';
+	}
+	/**
+	* End: Include for phase 2
+	*/
 	require dirname( __FILE__ ) . '/rest-api.php';
 }
 
@@ -43,6 +52,18 @@
 if ( ! function_exists( 'render_block_core_latest_posts' ) ) {
 	require dirname( __FILE__ ) . '/../packages/block-library/src/latest-posts/index.php';
 }
+
+
+/**
+ * Start: Include for phase 2
+ */
+if ( ! function_exists( 'render_block_legacy_widget' ) ) {
+	require dirname( __FILE__ ) . '/../packages/block-library/src/legacy-widget/index.php';
+}
+/**
+ * End: Include for phase 2
+ */
+
 if ( ! function_exists( 'render_block_core_rss' ) ) {
 	require dirname( __FILE__ ) . '/../packages/block-library/src/rss/index.php';
 }

lib/rest-api.php

@@ -51,3 +51,22 @@ function gutenberg_filter_oembed_result( $response, $handler, $request ) {
 	);
 }
 add_filter( 'rest_request_after_callbacks', 'gutenberg_filter_oembed_result', 10, 3 );
+
+
+
+/**
+ * Start: Include for phase 2
+ */
+/**
+ * Registers the REST API routes needed by the legacy widget block.
+ *
+ * @since 5.0.0
+ */
+function gutenberg_register_rest_widget_updater_routes() {
+	$widgets_controller = new WP_REST_Widget_Updater_Controller();
+	$widgets_controller->register_routes();
+}
+add_action( 'rest_api_init', 'gutenberg_register_rest_widget_updater_routes' );
+/**
+ * End: Include for phase 2
+ */