Add Allowed_Blocks library feature

Author: dlh01

CHANGELOG.md

@@ -15,6 +15,7 @@ Nothing yet.
 - `Ordered` feature.
 - `Each_Replaced` serialized blocks class.
 - `Alley\WP\Features\Library` namespace to hold a library of concrete feature implementations.
+- `Allowed_Blocks` library feature.
 - `Block_Content_Filter` library feature.
 - `Plugin_Loader` library feature.
 

docs/feature.md

@@ -25,6 +25,7 @@ All `Features` implementations also implement `Feature`.
 
 The `Library` subnamespace includes concrete implementations of common features. These can be used on their own or as part of a set of features that make up a larger integration.
 
+- [Allowed_Blocks](https://github.com/alleyinteractive/wp-type-extensions/blob/main/src/alley/wp/features/class-allowed-blocks.php): Limit blocks allowed in the editor to those that are explicitly supported.
 - [Block_Content_Filter](https://github.com/alleyinteractive/wp-type-extensions/blob/main/src/alley/wp/features/class-block-content-filter.php): Filter block markup in `the_content` for the post being viewed.
 - [GTM_Script](https://github.com/alleyinteractive/wp-type-extensions/blob/main/src/alley/wp/features/class-gtm-script.php): Add the standard Google Tag Manager script and data layer.
 - [Plugin_Loader](https://github.com/alleyinteractive/wp-type-extensions/blob/main/src/alley/wp/features/class-plugin-loader.php): Makes the [Alley plugin loader](https://github.com/alleyinteractive/wp-plugin-loader) available in a feature.

docs/features.md

@@ -27,6 +27,44 @@ use Alley\WP\Features\Template_Feature;
 // Main plugin features.
 $plugin = new Group();
 
+$plugin->include(
+  new Features\Allowed_Blocks(
+    context: 'core/edit-post',
+    allowed: new FastFailValidatorChain(
+      [
+        new AnyValidator(
+          [
+            // Allow all blocks from WP Curate.
+            new Regex( '/^wp-curate/' ),
+            // Allow these specific other blocks.
+            new OneOf(
+              [
+                'haystack' => [
+                  'core/cover',
+                  'core/embed',
+                  'core/gallery',
+                  'core/group',
+                  'core/heading',
+                  'core/image',
+                  'core/list',
+                  'core/list-item',
+                  'core/paragraph',
+                  'core/quote',
+                ],
+              ],
+            ),
+          ],
+        ),
+        new Not(
+          new Regex( '#^core/post-#' ),
+          'Post template blocks are not allowed in the post editor',
+        ),
+      ],
+    ),
+    registry: WP_Block_Type_Registry::get_instance(),
+  ),
+)
+
 // Load the Simple History plugin.
 $plugin->include(
   new Library\Plugin_Loader(

src/features/library/class-allowed-blocks.php

@@ -0,0 +1,71 @@
+<?php
+/**
+ * Allowed_Blocks class file
+ *
+ * @package wp-type-extensions
+ */
+
+namespace Alley\WP\Features\Library;
+
+use Alley\WP\Types\Feature;
+use Laminas\Validator\ValidatorInterface;
+use WP_Block_Editor_Context;
+use WP_Block_Type;
+use WP_Block_Type_Registry;
+
+/**
+ * Limit blocks allowed in the editor to those that are explicitly supported.
+ */
+final class Allowed_Blocks implements Feature {
+	/**
+	 * Set up.
+	 *
+	 * @param string|string[]        $context  Block editor context.
+	 * @param ValidatorInterface     $allowed  Allowed block names.
+	 * @param WP_Block_Type_Registry $registry Block type registry.
+	 */
+	public function __construct(
+		private readonly string|array $context,
+		private readonly ValidatorInterface $allowed,
+		private readonly WP_Block_Type_Registry $registry,
+	) {}
+
+	/**
+	 * Boot the feature.
+	 */
+	public function boot(): void {
+		add_filter( 'allowed_block_types_all', [ $this, 'filter_allowed_block_types' ], 10, 2 );
+	}
+
+	/**
+	 * Filters the allowed block types for all editor types.
+	 *
+	 * @param bool|string[]           $allowed_block_types  Array of block type slugs, or boolean to enable/disable all.
+	 * @param WP_Block_Editor_Context $block_editor_context The current block editor context.
+	 * @return bool|string[] Updated block type slugs.
+	 */
+	public function filter_allowed_block_types( $allowed_block_types, $block_editor_context ) {
+		if ( in_array( $block_editor_context->name, (array) $this->context, true ) ) {
+			$updated = array_reduce(
+				$this->registry->get_all_registered(),
+				function ( array $carry, WP_Block_Type $type ) {
+					if ( $this->allowed->isValid( $type->name ) ) {
+						$carry[] = $type->name;
+					}
+
+					return $carry;
+				},
+				[],
+			);
+
+			// If the filter already had an array of names, honor those, but test them.
+			if ( is_array( $allowed_block_types ) && count( $allowed_block_types ) > 0 ) {
+				array_push( $updated, ...array_filter( $allowed_block_types, [ $this->allowed, 'isValid' ] ) );
+			}
+
+			$allowed_block_types = $updated;
+		}
+
+		return $allowed_block_types;
+	}
+}