From bababb94e2dc4e113ca952a8c3e4fe697c25fef5 Mon Sep 17 00:00:00 2001
From: Bernie Reiter <ockham@raz.or.at>
Date: Wed, 24 Jan 2024 17:10:09 +0100
Subject: [PATCH] Update Navigation block to render hooked inner blocks

---
 .../wordpress-6.5/navigation-block-hooks.php  | 112 ++++++++++++++++++
 lib/load.php                                  |   1 +
 .../block-library/src/navigation/index.php    |  25 +++-
 3 files changed, 135 insertions(+), 3 deletions(-)
 create mode 100644 lib/compat/wordpress-6.5/navigation-block-hooks.php

diff --git a/lib/compat/wordpress-6.5/navigation-block-hooks.php b/lib/compat/wordpress-6.5/navigation-block-hooks.php
new file mode 100644
index 0000000000000..d7a0e888622d2
--- /dev/null
+++ b/lib/compat/wordpress-6.5/navigation-block-hooks.php
@@ -0,0 +1,112 @@
+<?php
+// Injection of hooked blocks into the Navigation block relies on some functions present in WP >= 6.4
+// that have not yet been included in Gutenberg's compatibility layer (lib/compat/wordpress-6.4/block-hooks.php).
+if ( function_exists( 'get_hooked_blocks' ) ) {
+	add_filter( 'rest_prepare_wp_navigation', 'gutenberg_hook_blocks_into_core_navigation_rest_response', 10, 3 );
+	add_action( 'rest_insert_wp_navigation', 'gutenberg_update_ignore_hooked_blocks_meta_core_navigation', 10, 3 );
+}
+
+/**
+ * Updates the post meta with the list of ignored hooked blocks when the navigation is created or updated via the REST API.
+ *
+ * @param WP_Post $post Post object.
+ */
+function gutenberg_update_ignore_hooked_blocks_meta_core_navigation( $post ) {
+	if ( ! isset( $post->ID ) ) {
+		return;
+	}
+
+	// We run the Block Hooks mechanism so it will return the list of ignored hooked blocks
+	// in the mock root Navigation block's metadata attribute.
+	// We ignore the rest of the returned `$markup`; `$post->post_content` already has the hooked
+	// blocks inserted, whereas `$markup` will have them inserted twice.
+	$blocks                = parse_blocks( $post->post_content );
+	$markup                = gutenberg_insert_hooked_blocks_into_navigation_block( $blocks, $post );
+	$root_nav_block        = parse_blocks( $markup )[0];
+	$ignored_hooked_blocks = isset( $root_nav_block['attrs']['metadata']['ignoredHookedBlocks'] )
+		? $root_nav_block['attrs']['metadata']['ignoredHookedBlocks']
+		: array();
+
+	if ( ! empty( $ignored_hooked_blocks ) ) {
+		$existing_ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
+		if ( ! empty( $existing_ignored_hooked_blocks ) ) {
+			$existing_ignored_hooked_blocks = json_decode( $existing_ignored_hooked_blocks, true );
+			$ignored_hooked_blocks          = array_unique( array_merge( $ignored_hooked_blocks, $existing_ignored_hooked_blocks ) );
+		}
+		update_post_meta( $post->ID, '_wp_ignored_hooked_blocks', json_encode( $ignored_hooked_blocks ) );
+	}
+}
+
+/**
+ * Hooks into the REST API response for the core/navigation block and adds the first and last inner blocks.
+ *
+ * @param WP_REST_Response $response The response object.
+ * @param WP_Post          $post     Post object.
+ * @param WP_REST_Request  $request  Request object.
+ * @return WP_REST_Response The response object.
+ */
+function gutenberg_hook_blocks_into_core_navigation_rest_response( $response, $post ) {
+	if ( ! isset( $response->data['content']['raw'] ) || ! isset( $response->data['content']['rendered'] ) ) {
+		return $response;
+	}
+	$parsed_blocks = parse_blocks( $response->data['content']['raw'] );
+	$content       = gutenberg_insert_hooked_blocks_into_navigation_block( $parsed_blocks, $post );
+
+	// Remove mock Navigation block wrapper.
+	$start   = strpos( $content, '-->' ) + strlen( '-->' );
+	$end     = strrpos( $content, '<!--' );
+	$content = substr( $content, $start, $end - $start );
+
+	$response->data['content']['raw']      = $content;
+	$response->data['content']['rendered'] = apply_filters( 'the_content', $content );
+
+	return $response;
+}
+
+/**
+ * Insert hooked blocks into a Navigation block.
+ *
+ * Given a Navigation block's inner blocks and its corresponding `wp_navigation` post object,
+ * this function inserts hooked blocks into it, and returns the serialized inner blocks in a
+ * mock Navigation block wrapper.
+ *
+ * If there are any hooked blocks that need to be inserted as the Navigation block's first or last
+ * children, the `wp_navigation` post's `_wp_ignored_hooked_blocks` meta is checked to see if any
+ * of those hooked blocks should be exempted from insertion.
+ *
+ * @param array   $inner_blocks Parsed inner blocks of a Navigation block.
+ * @param WP_Post $post         `wp_navigation` post object corresponding to the block.
+ * @return string Serialized inner blocks in mock Navigation block wrapper, with hooked blocks inserted, if any.
+ */
+function gutenberg_insert_hooked_blocks_into_navigation_block( $inner_blocks, $post = null ) {
+	$before_block_visitor = null;
+	$after_block_visitor  = null;
+	$hooked_blocks        = get_hooked_blocks();
+	$attributes           = array();
+
+	if ( isset( $post->ID ) ) {
+		$ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
+		if ( ! empty( $ignored_hooked_blocks ) ) {
+			$ignored_hooked_blocks  = json_decode( $ignored_hooked_blocks, true );
+			$attributes['metadata'] = array(
+				'ignoredHookedBlocks' => $ignored_hooked_blocks,
+			);
+		}
+	}
+
+	$mock_anchor_parent_block = array(
+		'blockName'    => 'core/navigation',
+		'attrs'        => $attributes,
+		'innerBlocks'  => $inner_blocks,
+		'innerContent' => array_fill( 0, count( $inner_blocks ), null ),
+	);
+	$before_block_visitor     = null;
+	$after_block_visitor      = null;
+
+	if ( ! empty( $hooked_blocks ) || has_filter( 'hooked_block_types' ) ) {
+		$before_block_visitor = make_before_block_visitor( $hooked_blocks, $post );
+		$after_block_visitor  = make_after_block_visitor( $hooked_blocks, $post );
+	}
+
+	return traverse_and_serialize_block( $mock_anchor_parent_block, $before_block_visitor, $after_block_visitor );
+}
diff --git a/lib/load.php b/lib/load.php
index ea443544d5be4..ee5a9e097f056 100644
--- a/lib/load.php
+++ b/lib/load.php
@@ -106,6 +106,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 // WordPress 6.5 compat.
 require __DIR__ . '/compat/wordpress-6.5/blocks.php';
 require __DIR__ . '/compat/wordpress-6.5/block-patterns.php';
+require __DIR__ . '/compat/wordpress-6.5/navigation-block-hooks.php';
 require __DIR__ . '/compat/wordpress-6.5/kses.php';
 require __DIR__ . '/compat/wordpress-6.5/class-wp-script-modules.php';
 require __DIR__ . '/compat/wordpress-6.5/scripts-modules.php';
diff --git a/packages/block-library/src/navigation/index.php b/packages/block-library/src/navigation/index.php
index 8b39a89022f8b..6df3cbf98dc75 100644
--- a/packages/block-library/src/navigation/index.php
+++ b/packages/block-library/src/navigation/index.php
@@ -190,11 +190,19 @@ private static function get_inner_blocks_from_navigation_post( $attributes ) {
 
 			// 'parse_blocks' includes a null block with '\n\n' as the content when
 			// it encounters whitespace. This code strips it.
-			$compacted_blocks = block_core_navigation_filter_out_empty_blocks( $parsed_blocks );
+			$blocks = block_core_navigation_filter_out_empty_blocks( $parsed_blocks );
+
+			if ( function_exists( 'get_hooked_blocks' ) ) {
+				// Run Block Hooks algorithm to inject hooked blocks.
+				$markup         = gutenberg_insert_hooked_blocks_into_navigation_block( $blocks, $navigation_post );
+				$root_nav_block = parse_blocks( $markup )[0];
+
+				$blocks = isset( $root_nav_block['innerBlocks'] ) ? $root_nav_block['innerBlocks'] : $blocks;
+			}
 
 			// TODO - this uses the full navigation block attributes for the
 			// context which could be refined.
-			return new WP_Block_List( $compacted_blocks, $attributes );
+			return new WP_Block_List( $blocks, $attributes );
 		}
 	}
 
@@ -983,6 +991,17 @@ function block_core_navigation_get_fallback_blocks() {
 		// Normalizing blocks may result in an empty array of blocks if they were all `null` blocks.
 		// In this case default to the (Page List) fallback.
 		$fallback_blocks = ! empty( $maybe_fallback ) ? $maybe_fallback : $fallback_blocks;
+
+		if ( function_exists( 'get_hooked_blocks' ) ) {
+			// Run Block Hooks algorithm to inject hooked blocks.
+			// We have to run it here because we need the post ID of the Navigation block to track ignored hooked blocks.
+			$markup = gutenberg_insert_hooked_blocks_into_navigation_block( $fallback_blocks, $navigation_post );
+			$blocks = parse_blocks( $markup );
+
+			if ( isset( $blocks[0]['innerBlocks'] ) ) {
+				$fallback_blocks = $blocks[0]['innerBlocks'];
+			}
+		}
 	}
 
 	/**
@@ -994,7 +1013,7 @@ function block_core_navigation_get_fallback_blocks() {
 	 *
 	 * @since 5.9.0
 	 *
-	 * @param array[] default fallback blocks provided by the default block mechanic.
+	 * @param array[] $fallback_blocks default fallback blocks provided by the default block mechanic.
 	 */
 	return apply_filters( 'block_core_navigation_render_fallback', $fallback_blocks );
 }