Activity: try to parse image IDs using blocks (#460)

This will prevent the issue of attaching images that don't were uploaded to the post but not used in the post

The post needs to be using blocks to get the introspection required.

includes/transformer/class-post.php

@@ -9,6 +9,7 @@ use Activitypub\Activity\Base_Object;
 use function Activitypub\esc_hashtag;
 use function Activitypub\is_single_user;
 use function Activitypub\get_rest_url_by_path;
+use function Activitypub\site_supports_blocks;
 
 /**
  * WordPress Post Transformer
@@ -166,6 +167,66 @@ class Post {
 		return Users::get_by_id( $this->wp_post->post_author )->get_url();
 	}
 
+	/**
+	 * Returns the Image Attachments for this Post, parsed from blocks.
+	 * @param int $max_images The maximum number of images to return.
+	 * @param array $image_ids The image IDs to append new IDs to.
+	 *
+	 * @return array The image IDs.
+	 */
+	protected function get_block_image_ids( $max_images, $image_ids = [] ) {
+		$blocks = \parse_blocks( $this->wp_post->post_content );
+		return self::get_image_ids_from_blocks( $blocks, $image_ids, $max_images );
+	}
+
+	/**
+	 * Recursively get image IDs from blocks.
+	 * @param array $blocks The blocks to search for image IDs
+	 * @param array $image_ids The image IDs to append new IDs to
+	 * @param int $max_images The maximum number of images to return.
+	 *
+	 * @return array The image IDs.
+	 */
+	protected static function get_image_ids_from_blocks( $blocks, $image_ids, $max_images ) {
+		foreach ( $blocks as $block ) {
+			// recurse into inner blocks
+			if ( ! empty( $block['innerBlocks'] ) ) {
+				$image_ids = self::get_image_ids_from_blocks( $block['innerBlocks'], $image_ids, $max_images );
+			}
+
+			switch ( $block['blockName'] ) {
+				case 'core/image':
+				case 'core/cover':
+					if ( ! empty( $block['attrs']['id'] ) ) {
+						$image_ids[] = $block['attrs']['id'];
+					}
+					break;
+				case 'jetpack/slideshow':
+				case 'jetpack/tiled-gallery':
+					if ( ! empty( $block['attrs']['ids'] ) ) {
+						$image_ids = array_merge( $image_ids, $block['attrs']['ids'] );
+					}
+					break;
+				case 'jetpack/image-compare':
+					if ( ! empty( $block['attrs']['beforeImageId'] ) ) {
+						$image_ids[] = $block['attrs']['beforeImageId'];
+					}
+					if ( ! empty( $block['attrs']['afterImageId'] ) ) {
+						$image_ids[] = $block['attrs']['afterImageId'];
+					}
+					break;
+			}
+
+			// we could be at or over max, stop unneeded work
+			if ( count( $image_ids ) >= $max_images ) {
+				break;
+			}
+		}
+
+		// still need to slice it because one gallery could knock us over the limit
+		return \array_slice( $image_ids, 0, $max_images );
+	}
+
 	/**
 	 * Generates all Image Attachments for a Post.
 	 *
@@ -192,21 +253,26 @@ class Post {
 		}
 
 		if ( $max_images > 0 ) {
-			// then list any image attachments
+			// first try to get images that are actually in the post content
-			$query = new \WP_Query(
+			if ( site_supports_blocks() && \has_blocks( $this->wp_post->post_content ) ) {
-				array(
+				$image_ids = $this->get_block_image_ids( $max_images, $image_ids );
-					'post_parent' => $id,
+			} else {
-					'post_status' => 'inherit',
+				// fallback to images attached to the post
-					'post_type' => 'attachment',
+				$query = new \WP_Query(
-					'post_mime_type' => 'image',
+					array(
-					'order' => 'ASC',
+						'post_parent' => $id,
-					'orderby' => 'menu_order ID',
+						'post_status' => 'inherit',
-					'posts_per_page' => $max_images,
+						'post_type' => 'attachment',
-				)
+						'post_mime_type' => 'image',
-			);
+						'order' => 'ASC',
-			foreach ( $query->get_posts() as $attachment ) {
+						'orderby' => 'menu_order ID',
-				if ( ! \in_array( $attachment->ID, $image_ids, true ) ) {
+						'posts_per_page' => $max_images,
-					$image_ids[] = $attachment->ID;
+					)
+				);
+				foreach ( $query->get_posts() as $attachment ) {
+					if ( ! \in_array( $attachment->ID, $image_ids, true ) ) {
+						$image_ids[] = $attachment->ID;
+					}
 				}
 			}
 		}