move common stuff to the Transformer_Base class.

includes/activity/class-event.php

@@ -0,0 +1,23 @@
+<?php
+/**
+ * Inspired by the PHP ActivityPub Library by @Landrok
+ *
+ * @link https://github.com/landrok/activitypub
+ */
+
+namespace Activitypub\Activity;
+
+use Activitypub\Activity\Base_Object;
+
+/**
+ * Event is an implementation of one of the
+ * Activity Streams Event object type
+ *
+ * The Object is the primary base type for the Activity Streams
+ * vocabulary.
+ *
+ * @see https://www.w3.org/TR/activitystreams-vocabulary/#dfn-event
+ */
+class Note extends Base_Object {
+    protected $type = 'Event';
+}

includes/activity/class-note.php

@@ -0,0 +1,23 @@
+<?php
+/**
+ * Inspired by the PHP ActivityPub Library by @Landrok
+ *
+ * @link https://github.com/landrok/activitypub
+ */
+
+namespace Activitypub\Activity;
+
+use Activitypub\Activity\Base_Object;
+
+/**
+ * Note is an implementation of one of the
+ * Activity Streams Note object type
+ *
+ * The Object is the primary base type for the Activity Streams
+ * vocabulary.
+ *
+ * @see https://www.w3.org/TR/activitystreams-vocabulary/#dfn-note
+ */
+class Note extends Base_Object {
+    protected $type = 'Note';
+}

includes/class-activity-dispatcher.php

@@ -5,7 +5,7 @@ use WP_Post;
 use Activitypub\Activity\Activity;
 use Activitypub\Collection\Users;
 use Activitypub\Collection\Followers;
-use Activitypub\Transformer\Post;
+use Activitypub\Transformers_Manager;
 
 use function Activitypub\is_single_user;
 use function Activitypub\is_user_disabled;
@@ -65,7 +65,9 @@ class Activity_Dispatcher {
 			return;
 		}
 
-		$object = Post::transform( $wp_post )->to_object();
+		$transformer = Transformers_Manager::get_transformer( $wp_post );
+		$transformer->transform( $wp_post );
+		$transformer->to_object();
 
 		$activity = new Activity();
 		$activity->set_type( $type );
@@ -101,7 +103,9 @@ class Activity_Dispatcher {
 			return;
 		}
 
-		$object = Post::transform( $wp_post )->to_object();
+		$transformer = Transformers_Manager::get_transformer( $wp_post );
+		$transformer->transform( $wp_post );
+		$transformer->to_object();
 
 		$activity = new Activity();
 		$activity->set_type( 'Announce' );

includes/class-activitypub.php

@@ -20,9 +20,9 @@ class Activitypub {
 		\add_filter( 'get_comment_link', array( self::class, 'remote_comment_link' ), 11, 3 );
 
 		// Add support for ActivityPub to custom post types
-		$post_types = \get_option( 'activitypub_support_post_types', array( 'post', 'page' ) ) ? \get_option( 'activitypub_support_post_types', array( 'post', 'page' ) ) : array();
+		$transformer_mapping = \get_option( 'activitypub_transformer_mapping', array( 'post' => 'activitypub/default', 'page' => 'activitypub/default' ) ) ? \get_option( 'activitypub_transformer_mapping', array( 'post' => 'activitypub/default', 'page' => 'activitypub/default' ) ) : array();
 
-		foreach ( $post_types as $post_type ) {
+		foreach ( array_keys( $transformer_mapping ) as $post_type ) {
 			\add_post_type_support( $post_type, 'activitypub' );
 		}
 

includes/class-admin.php

@@ -3,6 +3,7 @@ namespace Activitypub;
 
 use WP_User_Query;
 use Activitypub\Model\Blog_User;
+use Activitypub\Base\Transformer_Base;
 
 /**
  * ActivityPub Admin Class
@@ -22,6 +23,10 @@ class Admin {
 		if ( ! is_user_disabled( get_current_user_id() ) ) {
 			\add_action( 'show_user_profile', array( self::class, 'add_profile' ) );
 		}
+
+		add_filter( 'activitypub/transformers/is_transformer_enabled', function( $should_register, Transformer_Base $widget_instance ) {
+			return ! Options::is_transformer_disabled( $transformer_instance->get_name() );
+		}, 10, 2 );
 	}
 
 	/**
@@ -154,14 +159,48 @@ class Admin {
 				'default' => '0',
 			)
 		);
-		\register_setting(
+
+		/**
+		 * Flexible activation of post_types together with mapping ActivityPub transformers.
+		 * 
+		 * If a post-type is not mapped to any ActivtiyPub transformer it means it is not activated 
+		 * for ActivityPub federation.
+		 *
+		 * @since version_number_transformer_management_placeholder
+		 */
+		register_setting(
 			'activitypub',
-			'activitypub_support_post_types',
+			'activitypub_transformer_mapping',
 			array(
-				'type'         => 'string',
-				'description'  => \esc_html__( 'Enable ActivityPub support for post types', 'activitypub' ),
-				'show_in_rest' => true,
-				'default'      => array( 'post', 'pages' ),
+				'type'         => 'array',
+				'default'      => array(
+					'post' => 'note',
+				),
+				'show_in_rest' => array(
+					'schema' => array(
+						'type'  => 'array',
+						'items' => array(
+							'type' => 'string',
+						),
+					),
+				),
+				'sanitize_callback' => function ( $value ) {
+					// Check if $value is an array
+					if (!is_array($value)) {
+						return array();
+					}
+					$value_keys = array_keys( $value );
+
+					$all_public_post_types = \get_post_types( array( 'public' => true ), 'names' );
+
+					// Unset the keys that are missing in $keysToCheck
+					foreach ( array_diff( $value_keys, $all_public_post_types ) as $missing_key ) {
+						unset($value[$missing_key]);
+					}
+					// var_dump($value);
+					return $value;
+
+				}
 			)
 		);
 		\register_setting(

includes/class-scheduler.php

@@ -4,7 +4,6 @@ namespace Activitypub;
 
 use Activitypub\Collection\Users;
 use Activitypub\Collection\Followers;
-use Activitypub\Transformer\Post;
 
 /**
  * ActivityPub Scheduler Class

includes/class-transformer-base.php

@@ -0,0 +1,595 @@
+<?php
+/**
+ * Inspired by the PHP ActivityPub Library by @Landrok
+ *
+ * @link https://github.com/landrok/activitypub
+ */
+
+namespace Activitypub;
+
+use WP_Post;
+use Activitypub\Collection\Users;
+use Activitypub\Model\Blog_User;
+use Activitypub\Activity\Base_Object;
+use Activitypub\Shortcodes;
+use Activitypub\Transformer_Base;
+
+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;
+
+/**
+ * Base class to implement WordPress to ActivityPub transformers.
+ */
+abstract class Transformer_Base {
+	/**
+	 * The WP_Post object.
+	 *
+	 * @var WP_Post
+	 */
+	protected $wp_post;
+
+	/**
+	 * Assign WP_Post Object to a specific transformer instance.
+	 *
+	 * This helps to chain the output of the Transformer.
+	 *
+	 * @param WP_Post $wp_post The WP_Post object
+	 *
+	 * @return void
+	 */
+	public function set_wp_post( WP_Post $wp_post ) {
+		if ( $this->supports_post_type( get_post_type( $wp_post ) ) ) {
+			$this->wp_post = $wp_post;
+		} else {
+			//TODO Error, this should not happen.
+		}	
+	}
+
+    /**
+	 * Get the supported WP post_types that the transformer can use as an input.
+	 *
+     * By default all post types are supported.
+	 * You may very likely wish to override this function.
+     * 
+	 * @since version_number_transformer_management_placeholder
+     * @return string[] An array containing all the supported post types.
+	 */
+    public function get_supported_post_types() {
+        return \get_post_types( array( 'public' => true ), 'names' );
+    }
+
+    /**
+	 * Get the name of the plugin that registered the transformer.
+     * 
+     * @see Forked from the WordPress elementor plugin.
+     * 
+	 * @since version_number_transformer_management_placeholder
+     * @return string Plugin name
+	 */
+    private function get_plugin_name_from_transformer_instance( $transformer ) {
+		$class_reflection = new \ReflectionClass( $transformer );
+
+		$plugin_basename = plugin_basename( $class_reflection->getFileName() );
+
+		$plugin_directory = strtok( $plugin_basename, '/' );
+
+		$plugins_data = get_plugins( '/' . $plugin_directory );
+		$plugin_data = array_shift( $plugins_data );
+
+		return $plugin_data['Name'] ?? esc_html__( 'Unknown', 'activitypub' );
+	}
+
+    /**
+	 * Return whether the transformer supports a post type.
+	 *
+	 * @since version_number_transformer_management_placeholder
+     * 
+     * @return string post_type Post type name.
+	 */
+    final public function supports_post_type( $post_type ) {
+		return in_array( $post_type, $this->get_supported_post_types() );
+	}
+
+    /**
+	 * Get the name used for registering the transformer with the ActivityPub plugin.
+	 *
+	 * @since version_number_transformer_management_placeholder
+     * 
+     * @return string name
+	 */
+    abstract public function get_name();
+
+    /**
+	 * Get the display name for the ActivityPub transformer.
+	 *
+	 * @since version_number_transformer_management_placeholder
+     * 
+     * @return string display name
+	 */
+    abstract public function get_label();
+
+	/**
+	 * Returns the ActivityStreams 2.0 Object-Type for a Post.
+	 *
+	 * @see https://www.w3.org/TR/activitystreams-vocabulary/#activity-types
+	 *
+	 * @return string The Object-Type.
+	 */
+	abstract protected function get_object_type();
+	
+	/**
+	 * Returns the content for the ActivityPub Item.
+	 *
+	 * The content will be generated based on the user settings.
+	 *
+	 * @return string The content.
+	 */
+	protected function get_content() {
+		global $post;
+
+		/**
+		 * Provides an action hook so plugins can add their own hooks/filters before AP content is generated.
+		 *
+		 * Example: if a plugin adds a filter to `the_content` to add a button to the end of posts, it can also remove that filter here.
+		 *
+		 * @param WP_Post $post The post object.
+		 */
+		do_action( 'activitypub_before_get_content', $post );
+
+		// phpcs:ignore WordPress.WP.GlobalVariablesOverride.Prohibited
+		$post    = $this->wp_post;
+		$content = $this->get_post_content_template();
+
+		// Register our shortcodes just in time.
+		Shortcodes::register();
+		// Fill in the shortcodes.
+		setup_postdata( $post );
+		$content = do_shortcode( $content );
+		wp_reset_postdata();
+
+		$content = \wpautop( $content );
+		$content = \preg_replace( '/[\n\r\t]/', '', $content );
+		$content = \trim( $content );
+
+		$content = \apply_filters( 'activitypub_the_content', $content, $post );
+
+		// Don't need these any more, should never appear in a post.
+		Shortcodes::unregister();
+
+		return $content;
+	}
+
+
+		/**
+	 * Returns the ID of the Post.
+	 *
+	 * @return string The Posts ID.
+	 */
+	public function get_id() {
+		return $this->get_url();
+	}
+
+	/**
+	 * Returns the URL of the Post.
+	 *
+	 * @return string The Posts URL.
+	 */
+	public function get_url() {
+		$post = $this->wp_post;
+
+		if ( 'trash' === get_post_status( $post ) ) {
+			$permalink = \get_post_meta( $post->ID, 'activitypub_canonical_url', true );
+		} else {
+			$permalink = \get_permalink( $post );
+		}
+
+		return \esc_url( $permalink );
+	}
+
+	/**
+	 * Returns the User-URL of the Author of the Post.
+	 *
+	 * If `single_user` mode is enabled, the URL of the Blog-User is returned.
+	 *
+	 * @return string The User-URL.
+	 */
+	protected function get_attributed_to() {
+		if ( is_single_user() ) {
+			$user = new Blog_User();
+			return $user->get_url();
+		}
+
+		return Users::get_by_id( $this->wp_post->post_author )->get_url();
+	}
+
+	/**
+	 * Generates all Media Attachments for a Post.
+	 *
+	 * @return array The Attachments.
+	 */
+	protected function get_attachments() {
+		// Once upon a time we only supported images, but we now support audio/video as well.
+		// We maintain the image-centric naming for backwards compatibility.
+		$max_media = intval( \apply_filters( 'activitypub_max_image_attachments', \get_option( 'activitypub_max_image_attachments', ACTIVITYPUB_MAX_IMAGE_ATTACHMENTS ) ) );
+
+		if ( site_supports_blocks() && \has_blocks( $this->wp_post->post_content ) ) {
+			return $this->get_block_attachments( $max_media );
+		}
+
+		return $this->get_classic_editor_images( $max_media );
+	}
+
+	/**
+	 * Get media attachments from blocks. They will be formatted as ActivityPub attachments, not as WP attachments.
+	 *
+	 * @param int $max_media The maximum number of attachments to return.
+	 *
+	 * @return array The attachments.
+	 */
+	protected function get_block_attachments( $max_media ) {
+		// max media can't be negative or zero
+		if ( $max_media <= 0 ) {
+			return array();
+		}
+
+		$id = $this->wp_post->ID;
+
+		$media_ids = array();
+
+		// list post thumbnail first if this post has one
+		if ( \function_exists( 'has_post_thumbnail' ) && \has_post_thumbnail( $id ) ) {
+			$media_ids[] = \get_post_thumbnail_id( $id );
+		}
+
+		if ( $max_media > 0 ) {
+			$blocks = \parse_blocks( $this->wp_post->post_content );
+			$media_ids = self::get_media_ids_from_blocks( $blocks, $media_ids, $max_media );
+		}
+		$media_ids = \array_unique( $media_ids );
+
+		return \array_filter( \array_map( array( self::class, 'wp_attachment_to_activity_attachment' ), $media_ids ) );
+	}
+
+	/**
+	 * Get image attachments from the classic editor.
+	 * Note that audio/video attachments are only supported in the block editor.
+	 *
+	 * @param int $max_images The maximum number of images to return.
+	 *
+	 * @return array The attachments.
+	 */
+	protected function get_classic_editor_images( $max_images ) {
+		// max images can't be negative or zero
+		if ( $max_images <= 0 ) {
+			return array();
+		}
+
+		$id = $this->wp_post->ID;
+
+		$image_ids = array();
+
+		// list post thumbnail first if this post has one
+		if ( \function_exists( 'has_post_thumbnail' ) && \has_post_thumbnail( $id ) ) {
+			$image_ids[] = \get_post_thumbnail_id( $id );
+			--$max_images;
+		}
+
+		if ( $max_images > 0 ) {
+			$query = new \WP_Query(
+				array(
+					'post_parent' => $id,
+					'post_status' => 'inherit',
+					'post_type' => 'attachment',
+					'post_mime_type' => 'image',
+					'order' => 'ASC',
+					'orderby' => 'menu_order ID',
+					'posts_per_page' => $max_images,
+				)
+			);
+			foreach ( $query->get_posts() as $attachment ) {
+				if ( ! \in_array( $attachment->ID, $image_ids, true ) ) {
+					$image_ids[] = $attachment->ID;
+				}
+			}
+		}
+		$image_ids = \array_unique( $image_ids );
+
+		return \array_filter( \array_map( array( self::class, 'wp_attachment_to_activity_attachment' ), $image_ids ) );
+	}
+
+	/**
+	 * Recursively get media IDs from blocks.
+	 * @param array $blocks The blocks to search for media IDs
+	 * @param array $media_ids The media IDs to append new IDs to
+	 * @param int $max_media The maximum number of media to return.
+	 *
+	 * @return array The image IDs.
+	 */
+	protected static function get_media_ids_from_blocks( $blocks, $media_ids, $max_media ) {
+
+		foreach ( $blocks as $block ) {
+			// recurse into inner blocks
+			if ( ! empty( $block['innerBlocks'] ) ) {
+				$media_ids = self::get_media_ids_from_blocks( $block['innerBlocks'], $media_ids, $max_media );
+			}
+
+			switch ( $block['blockName'] ) {
+				case 'core/image':
+				case 'core/cover':
+				case 'core/audio':
+				case 'core/video':
+				case 'videopress/video':
+					if ( ! empty( $block['attrs']['id'] ) ) {
+						$media_ids[] = $block['attrs']['id'];
+					}
+					break;
+				case 'jetpack/slideshow':
+				case 'jetpack/tiled-gallery':
+					if ( ! empty( $block['attrs']['ids'] ) ) {
+						$media_ids = array_merge( $media_ids, $block['attrs']['ids'] );
+					}
+					break;
+				case 'jetpack/image-compare':
+					if ( ! empty( $block['attrs']['beforeImageId'] ) ) {
+						$media_ids[] = $block['attrs']['beforeImageId'];
+					}
+					if ( ! empty( $block['attrs']['afterImageId'] ) ) {
+						$media_ids[] = $block['attrs']['afterImageId'];
+					}
+					break;
+			}
+
+			// stop doing unneeded work
+			if ( count( $media_ids ) >= $max_media ) {
+				break;
+			}
+		}
+
+		// still need to slice it because one gallery could knock us over the limit
+		return array_slice( $media_ids, 0, $max_media );
+	}
+
+	/**
+	 * Converts a WordPress Attachment to an ActivityPub Attachment.
+	 *
+	 * @param int $id The Attachment ID.
+	 *
+	 * @return array The ActivityPub Attachment.
+	 */
+	public static function wp_attachment_to_activity_attachment( $id ) {
+		$attachment = array();
+		$mime_type = \get_post_mime_type( $id );
+		$mime_type_parts = \explode( '/', $mime_type );
+		// switching on image/audio/video
+		switch ( $mime_type_parts[0] ) {
+			case 'image':
+				$image_size = 'full';
+
+				/**
+				 * Filter the image URL returned for each post.
+				 *
+				 * @param array|false $thumbnail The image URL, or false if no image is available.
+				 * @param int         $id        The attachment ID.
+				 * @param string      $image_size The image size to retrieve. Set to 'full' by default.
+				 */
+				$thumbnail = apply_filters(
+					'activitypub_get_image',
+					self::get_image( $id, $image_size ),
+					$id,
+					$image_size
+				);
+
+				if ( $thumbnail ) {
+					$alt   = \get_post_meta( $id, '_wp_attachment_image_alt', true );
+					$image = array(
+						'type'      => 'Image',
+						'url'       => $thumbnail[0],
+						'mediaType' => $mime_type,
+					);
+
+					if ( $alt ) {
+						$image['name'] = $alt;
+					}
+					$attachment = $image;
+				}
+				break;
+
+			case 'audio':
+			case 'video':
+				$attachment = array(
+					'type'      => 'Document',
+					'mediaType' => $mime_type,
+					'url'       => \wp_get_attachment_url( $id ),
+					'name'      => \get_the_title( $id ),
+				);
+				$meta = wp_get_attachment_metadata( $id );
+				// height and width for videos
+				if ( isset( $meta['width'] ) && isset( $meta['height'] ) ) {
+					$attachment['width'] = $meta['width'];
+					$attachment['height'] = $meta['height'];
+				}
+				// @todo: add `icon` support for audio/video attachments. Maybe use post thumbnail?
+				break;
+		}
+
+		return \apply_filters( 'activitypub_attachment', $attachment, $id );
+	}
+
+	/**
+	 * Return details about an image attachment.
+	 *
+	 * @param int    $id         The attachment ID.
+	 * @param string $image_size The image size to retrieve. Set to 'full' by default.
+	 *
+	 * @return array|false Array of image data, or boolean false if no image is available.
+	 */
+	protected static function get_image( $id, $image_size = 'full' ) {
+		/**
+		 * Hook into the image retrieval process. Before image retrieval.
+		 *
+		 * @param int    $id         The attachment ID.
+		 * @param string $image_size The image size to retrieve. Set to 'full' by default.
+		 */
+		do_action( 'activitypub_get_image_pre', $id, $image_size );
+
+		$image = \wp_get_attachment_image_src( $id, $image_size );
+
+		/**
+		 * Hook into the image retrieval process. After image retrieval.
+		 *
+		 * @param int    $id         The attachment ID.
+		 * @param string $image_size The image size to retrieve. Set to 'full' by default.
+		 */
+		do_action( 'activitypub_get_image_post', $id, $image_size );
+
+		return $image;
+	}
+
+
+	/**
+	 * Helper function to get the @-Mentions from the post content.
+	 *
+	 * @return array The list of @-Mentions.
+	 */
+	protected function get_mentions() {
+		return apply_filters( 'activitypub_extract_mentions', array(), $this->wp_post->post_content, $this->wp_post );
+	}
+
+		/**
+	 * Returns a list of Mentions, used in the Post.
+	 *
+	 * @see https://docs.joinmastodon.org/spec/activitypub/#Mention
+	 *
+	 * @return array The list of Mentions.
+	 */
+	protected function get_cc() {
+		$cc = array();
+
+		$mentions = $this->get_mentions();
+		if ( $mentions ) {
+			foreach ( $mentions as $url ) {
+				$cc[] = $url;
+			}
+		}
+
+		return $cc;
+	}
+
+	/**
+	 * Returns a list of Tags, used in the Post.
+	 *
+	 * This includes Hash-Tags and Mentions.
+	 *
+	 * @return array The list of Tags.
+	 */
+	protected function get_tags() {
+		$tags = array();
+
+		$post_tags = \get_the_tags( $this->wp_post->ID );
+		if ( $post_tags ) {
+			foreach ( $post_tags as $post_tag ) {
+				$tag = array(
+					'type' => 'Hashtag',
+					'href' => \esc_url( \get_tag_link( $post_tag->term_id ) ),
+					'name' => esc_hashtag( $post_tag->name ),
+				);
+				$tags[] = $tag;
+			}
+		}
+
+		$mentions = $this->get_mentions();
+		if ( $mentions ) {
+			foreach ( $mentions as $mention => $url ) {
+				$tag = array(
+					'type' => 'Mention',
+					'href' => \esc_url( $url ),
+					'name' => \esc_html( $mention ),
+				);
+				$tags[] = $tag;
+			}
+		}
+
+		return $tags;
+	}
+
+
+	/**
+	 * Returns the locale of the post.
+	 *
+	 * @return string The locale of the post.
+	 */
+	public function get_locale() {
+		$post_id = $this->wp_post->ID;
+		$lang    = \strtolower( \strtok( \get_locale(), '_-' ) );
+
+		/**
+		 * Filter the locale of the post.
+		 *
+		 * @param string  $lang    The locale of the post.
+		 * @param int     $post_id The post ID.
+		 * @param WP_Post $post    The post object.
+		 *
+		 * @return string The filtered locale of the post.
+		 */
+		return apply_filters( 'activitypub_post_locale', $lang, $post_id, $this->wp_post );
+	}
+
+	/**
+	 * Gets the contentMap
+	 * 
+	 * @see https://www.w3.org/TR/activitystreams-vocabulary/#dfn-contentmap
+	 * 
+	 * @return array the contenmap
+	 */
+	protected function get_content_map() {
+		return array(
+			$this->get_locale() => $this->get_content(),
+		);
+	}
+
+	/**
+	 * Transforms the WP_Post object to an ActivityPub Object
+	 *
+	 * @see \Activitypub\Activity\Base_Object
+	 *
+	 * @return \Activitypub\Activity\Base_Object The ActivityPub Object
+	 */
+	public function to_object() {
+		$wp_post = $this->wp_post;
+		$object = new Base_Object();
+
+		$object->set_id( $this->get_id() );
+		$object->set_url( $this->get_url() );
+		$object->set_type( $this->get_object_type() );
+
+		$published = \strtotime( $wp_post->post_date_gmt );
+
+		$object->set_published( \gmdate( 'Y-m-d\TH:i:s\Z', $published ) );
+
+		$updated = \strtotime( $wp_post->post_modified_gmt );
+
+		if ( $updated > $published ) {
+			$object->set_updated( \gmdate( 'Y-m-d\TH:i:s\Z', $updated ) );
+		}
+
+		$object->set_attributed_to( $this->get_attributed_to() );
+		$object->set_content( $this->get_content() );
+		$object->set_content_map( $this->get_content_map );
+		$path = sprintf( 'users/%d/followers', intval( $wp_post->post_author ) );
+
+		$object->set_to(
+			array(
+				'https://www.w3.org/ns/activitystreams#Public',
+				get_rest_url_by_path( $path ),
+			)
+		);
+		$object->set_cc( $this->get_cc() );
+		$object->set_attachment( $this->get_attachments() );
+		$object->set_tag( $this->get_tags() );
+
+		return $object;
+	}
+
+}

includes/class-transformers-manager.php

@@ -0,0 +1,284 @@
+<?php
+/**
+ * Inspired by the way elementor handles addons.
+ *
+ * @link https://github.com/elementor/elementor/
+ */
+
+namespace Activitypub;
+
+use WP_Post;
+use WP_Comment;
+
+use function Activitypub\camel_to_snake_case;
+use function Activitypub\snake_to_camel_case;
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly.
+}
+
+/**
+ * ActivityPub transformers manager.
+ *
+ * ActivityPub transformers manager handler class is responsible for registering and
+ * initializing all the supported WP-Pobject to ActivityPub transformers.
+ *
+ * @since version_number_transformer_management_placeholder
+ */
+
+class Transformers_Manager {
+	/**
+	 * Transformers.
+	 *
+	 * Holds the list of all the ActivityPub transformers. Default is `null`.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access private
+	 *
+	 * @var \ActivityPub\Transformer_Base[]
+	 */
+	private $transformers = null;
+
+	/**
+	 * Module instance.
+	 *
+	 * Holds the transformer instance.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access protected
+	 *
+	 * @var Module
+	 */
+	protected static $_instances = [];
+
+
+	/**
+	 * Instance.
+	 *
+	 * Ensures only one instance of the transformer manager class is loaded or can be loaded.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access public
+	 * @static
+	 *
+	 * @return Module An instance of the class.
+	 */
+	public static function instance() {
+		$class_name = static::class_name();
+
+		if ( empty( static::$_instances[ $class_name ] ) ) {
+			static::$_instances[ $class_name ] = new static();
+		}
+
+		return static::$_instances[ $class_name ];
+	}
+
+	/**
+	 * Class name.
+	 *
+	 * Retrieve the name of the class.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access public
+	 * @static
+	 */
+	public static function class_name() {
+		return get_called_class();
+	}
+
+    /**
+	 * Transformers manager constructor.
+	 *
+	 * Initializing ActivityPub transformers manager.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access public
+	*/
+	public function __construct() {
+		$this->require_files();
+	}
+
+	/**
+	 * Require files.
+	 *
+	 * Require ActivityPub transformer base class.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access private
+	*/
+	private function require_files() {
+		require ACTIVITYPUB_PLUGIN_DIR . 'includes/class-transformer-base.php';
+	}
+
+	/**
+	 * Checks if a transformer is registered.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 *
+	 * @param string $name Transformer name including namespace.
+	 * @return bool True if the block type is registered, false otherwise.
+	 */
+	public function is_registered( $name ) {
+		return isset( $this->transformers[ $name ] );
+	}
+
+	/**
+	 * Register a transformer.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access public
+	 *
+	 * @param \ActivityPub\Transformer_Base $transformer_instance ActivityPub Transformer.
+	 *
+	 * @return bool True if the ActivityPub transformer was registered.
+	 */
+	public function register( Transformer_Base $transformer_instance) {
+
+		if ( ! $transformer_instance instanceof Transformer_Base ) {
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'ActivityPub transformer instance must be a of \ActivityPub\Transformer_Base class.' ),
+				'version_number_transformer_management_placeholder'
+			);
+			return false;
+		}
+		
+		$transformer_name = $transformer_instance->get_name();
+		if ( preg_match( '/[A-Z]+/', $transformer_name ) ) {
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'ActivityPub transformer names must not contain uppercase characters.' ),
+				'version_number_transformer_management_placeholder'
+			);
+			return false;
+		}
+
+		$name_matcher = '/^[a-z0-9-]+\/[a-z0-9-]+$/';
+		if ( ! preg_match( $name_matcher, $transformer_name ) ) {
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'ActivityPub transformer names must contain a namespace prefix. Example: my-plugin/my-custom-transformer' ),
+				'version_number_transformer_management_placeholder'
+			);
+			return false;
+		}
+
+		if ( $this->is_registered( $transformer_name ) ) {
+			_doing_it_wrong(
+				__METHOD__,
+				/* translators: %s: Block name. */
+				sprintf( __( 'ActivityPub transformer with name "%s" is already registered.' ), $transformer_name ),
+				'version_number_transformer_management_placeholder'
+			);
+			return false;
+		}	
+
+		/**
+		 * Should the ActivityPub transformer be registered.
+		 *
+		 * @since version_number_transformer_management_placeholder
+		 *
+		 * @param bool $should_register Should the ActivityPub transformer be registered. Default is `true`.
+		 * @param \ActivityPub\Transformer_Base $transformer_instance Widget instance.
+		 */
+		// TODO: does not implementing this slow down the website? -> compare with gutenberg block registration.
+		// $should_register = apply_filters( 'activitypub/transformers/is_transformer_enabled', true, $transformer_instance );
+
+		// if ( ! $should_register ) {
+		// 	return false;
+		// }
+
+		$this->transformers[ $transformer_name ] = $transformer_instance;
+
+		return true;
+	}
+
+	/**
+	 * Init transformers.
+	 *
+	 * Initialize ActivityPub transformer manager.
+	 * Include the builtin transformers by default and add third party ones.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access private
+	*/
+	private function init_transformers() {
+		$builtin_transformers = [
+			'post'
+		];
+
+		$this->transformers = [];
+
+		foreach ( $builtin_transformers as $transformer_name ) {
+			include ACTIVITYPUB_PLUGIN_DIR . 'includes/transformer/class-' . $transformer_name . '.php';
+
+			$class_name = ucfirst( $transformer_name );
+
+			$class_name = '\Activitypub\Transformer_' . $class_name;
+
+			$this->register( new $class_name() );
+		}
+
+		/**
+		 * Let other transformers register.
+		 *
+		 * Fires after the built-in Activitypub transformers are registered.
+		 *
+		 * @since version_number_transformer_management_placeholder
+		 *
+		 * @param Transformers_Manager $this The widgets manager.
+		 */
+		do_action( 'activitypub/transformers/register', $this );
+	}
+
+
+	/**
+	 * Get available ActivityPub transformers.
+	 *
+	 * Retrieve the registered transformers list. If given a transformer name
+	 * it returns the given transformer if it is registered.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access public
+	 *
+	 * @param string $transformers Optional. Transformer name. Default is null.
+	 *
+	 * @return Transformer_Base|Transformer_Base[]|null Registered transformers.
+	*/
+	public function get_transformers( $transformer_name = null ) {
+		if ( is_null( $this->transformers ) ) {
+			$this->init_transformers();
+		}
+
+		if ( null !== $transformer_name ) {
+			return isset( $this->transformers[ $transformer_name ] ) ? $this->transformers[ $transformer_name ] : null;
+		}
+
+		return $this->transformers;
+	}
+
+	/**
+	 * Get the mapped ActivityPub transformer.
+	 *
+	 * @since version_number_transformer_management_placeholder
+	 * @access public
+	 *
+     * @param WP_Post|WP_Comment $wp_post The WordPress Post/Comment.
+	 *
+	 * @return Transformer_Base|null Registered transformers.
+	*/
+	public function get_transformer( $object ) {
+		switch ( get_class( $object ) ) {
+			case 'WP_Post':
+				$post_type = get_post_type( $object );
+				$transformer_mapping = \get_option( 'activitypub_transformer_mapping', array( 'post' => 'activitypub/default', 'page' => 'activitypub/default' ) ) ? \get_option( 'activitypub_transformer_mapping', array( 'post' => 'activitypub/default', 'page' => 'activitypub/default' ) ) : array();
+				$transformer_name = $transformer_mapping[ $post_type ];
+				return new ( $this->get_transformers( $transformer_name ) );
+			case 'WP_Comment':
+				return new Comment( $object );
+			default:
+				return apply_filters( 'activitypub_transformer', null, $object, get_class( $object ) );
+		}
+	}
+}	
+

includes/model/class-post.php

@@ -1,7 +1,7 @@
 <?php
 namespace Activitypub\Model;
 
-use Activitypub\Transformer\Post as Post_Transformer;
+use Activitypub\Transformer_Post as Post_Transformer;
 
 /**
  * ActivityPub Post Class
@@ -31,10 +31,10 @@ class Post {
 	 */
 	// phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.FoundAfterLastUsed, VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable
 	public function __construct( $post, $post_author = null ) {
-		_deprecated_function( __CLASS__, '1.0.0', '\Activitypub\Transformer\Post' );
+		_deprecated_function( __CLASS__, '1.0.0', '\Activitypub\Transformer_Post' );
 
 		$this->post   = $post;
-		$this->object = Post_Transformer::transform( $post )->to_object();
+		$this->object = Post_Transformer->set_wp_post( $post )->to_object();
 	}
 
 	/**

includes/rest/class-collection.php

@@ -4,7 +4,7 @@ namespace Activitypub\Rest;
 use WP_Error;
 use WP_REST_Server;
 use WP_REST_Response;
-use Activitypub\Transformer\Post;
+use Activitypub\Transformers_Manager;
 use Activitypub\Activity\Activity;
 use Activitypub\Collection\Users as User_Collection;
 
@@ -168,7 +168,7 @@ class Collection {
 		);
 
 		foreach ( $posts as $post ) {
-			$response['orderedItems'][] = Post::transform( $post )->to_object()->to_array();
+			$response['orderedItems'][] = Transformers_Manager::get_transformer( $post )->transform( $post )->to_object()->to_array();
 		}
 
 		$rest_response = new WP_REST_Response( $response, 200 );

includes/rest/class-outbox.php

@@ -5,7 +5,7 @@ use stdClass;
 use WP_Error;
 use WP_REST_Server;
 use WP_REST_Response;
-use Activitypub\Transformer\Post;
+use Activitypub\Transformers_Manager;
 use Activitypub\Activity\Activity;
 use Activitypub\Collection\Users as User_Collection;
 
@@ -59,7 +59,7 @@ class Outbox {
 			return $user;
 		}
 
-		$post_types = \get_option( 'activitypub_support_post_types', array( 'post', 'page' ) );
+		$post_types = array_keys( \get_option( 'activitypub_transformer_mapping', array( 'post' => 'activitypub/default', 'page' => 'activitypub/default') ) );
 
 		$page = $request->get_param( 'page', 1 );
 
@@ -105,7 +105,9 @@ class Outbox {
 			);
 
 			foreach ( $posts as $post ) {
-				$post = Post::transform( $post )->to_object();
+				$transformer = Transformers_Manager::get_transformer( $wp_post );
+				$transformer->transform( $wp_post );
+				$post = $transformer->to_object();
 				$activity = new Activity();
 				$activity->set_type( 'Create' );
 				$activity->set_context( null );

includes/transformer/class-post.php

@@ -1,11 +1,12 @@
 <?php
-namespace Activitypub\Transformer;
+namespace Activitypub;
 
 use WP_Post;
 use Activitypub\Collection\Users;
 use Activitypub\Model\Blog_User;
 use Activitypub\Activity\Base_Object;
 use Activitypub\Shortcodes;
+use Activitypub\Transformer_Base;
 
 use function Activitypub\esc_hashtag;
 use function Activitypub\is_single_user;
@@ -14,375 +15,31 @@ use function Activitypub\site_supports_blocks;
 
 /**
  * WordPress Post Transformer
- *
  * The Post Transformer is responsible for transforming a WP_Post object into different othe
  * Object-Types.
  *
+ *
  * Currently supported are:
  *
  * - Activitypub\Activity\Base_Object
  */
-class Post {
-
+class Transformer_Post extends Transformer_Base {
 	/**
-	 * The WP_Post object.
+	 * Getter function for the name of the transformer.
 	 *
-	 * @var WP_Post
+	 * @return string name
 	 */
-	protected $wp_post;
-
-	/**
-	 * Static function to Transform a WP_Post Object.
-	 *
-	 * This helps to chain the output of the Transformer.
-	 *
-	 * @param WP_Post $wp_post The WP_Post object
-	 *
-	 * @return void
-	 */
-	public static function transform( WP_Post $wp_post ) {
-		return new static( $wp_post );
+	public function get_name() {
+		return 'activitypub/default';
 	}
 
 	/**
+	 * Getter function for the display name (label/title) of the transformer.
 	 *
-	 *
-	 * @param WP_Post $wp_post
+	 * @return string name
 	 */
-	public function __construct( WP_Post $wp_post ) {
-		$this->wp_post = $wp_post;
-	}
-
-	/**
-	 * Transforms the WP_Post object to an ActivityPub Object
-	 *
-	 * @see \Activitypub\Activity\Base_Object
-	 *
-	 * @return \Activitypub\Activity\Base_Object The ActivityPub Object
-	 */
-	public function to_object() {
-		$wp_post = $this->wp_post;
-		$object = new Base_Object();
-
-		$object->set_id( $this->get_id() );
-		$object->set_url( $this->get_url() );
-		$object->set_type( $this->get_object_type() );
-
-		$published = \strtotime( $wp_post->post_date_gmt );
-
-		$object->set_published( \gmdate( 'Y-m-d\TH:i:s\Z', $published ) );
-
-		$updated = \strtotime( $wp_post->post_modified_gmt );
-
-		if ( $updated > $published ) {
-			$object->set_updated( \gmdate( 'Y-m-d\TH:i:s\Z', $updated ) );
-		}
-
-		$object->set_attributed_to( $this->get_attributed_to() );
-		$object->set_content( $this->get_content() );
-		$object->set_content_map(
-			array(
-				$this->get_locale() => $this->get_content(),
-			)
-		);
-		$path = sprintf( 'users/%d/followers', intval( $wp_post->post_author ) );
-
-		$object->set_to(
-			array(
-				'https://www.w3.org/ns/activitystreams#Public',
-				get_rest_url_by_path( $path ),
-			)
-		);
-		$object->set_cc( $this->get_cc() );
-		$object->set_attachment( $this->get_attachments() );
-		$object->set_tag( $this->get_tags() );
-
-		return $object;
-	}
-
-	/**
-	 * Returns the ID of the Post.
-	 *
-	 * @return string The Posts ID.
-	 */
-	public function get_id() {
-		return $this->get_url();
-	}
-
-	/**
-	 * Returns the URL of the Post.
-	 *
-	 * @return string The Posts URL.
-	 */
-	public function get_url() {
-		$post = $this->wp_post;
-
-		if ( 'trash' === get_post_status( $post ) ) {
-			$permalink = \get_post_meta( $post->ID, 'activitypub_canonical_url', true );
-		} else {
-			$permalink = \get_permalink( $post );
-		}
-
-		return \esc_url( $permalink );
-	}
-
-	/**
-	 * Returns the User-URL of the Author of the Post.
-	 *
-	 * If `single_user` mode is enabled, the URL of the Blog-User is returned.
-	 *
-	 * @return string The User-URL.
-	 */
-	protected function get_attributed_to() {
-		if ( is_single_user() ) {
-			$user = new Blog_User();
-			return $user->get_url();
-		}
-
-		return Users::get_by_id( $this->wp_post->post_author )->get_url();
-	}
-
-	/**
-	 * Generates all Media Attachments for a Post.
-	 *
-	 * @return array The Attachments.
-	 */
-	protected function get_attachments() {
-		// Once upon a time we only supported images, but we now support audio/video as well.
-		// We maintain the image-centric naming for backwards compatibility.
-		$max_media = intval( \apply_filters( 'activitypub_max_image_attachments', \get_option( 'activitypub_max_image_attachments', ACTIVITYPUB_MAX_IMAGE_ATTACHMENTS ) ) );
-
-		if ( site_supports_blocks() && \has_blocks( $this->wp_post->post_content ) ) {
-			return $this->get_block_attachments( $max_media );
-		}
-
-		return $this->get_classic_editor_images( $max_media );
-	}
-
-	/**
-	 * Get media attachments from blocks. They will be formatted as ActivityPub attachments, not as WP attachments.
-	 *
-	 * @param int $max_media The maximum number of attachments to return.
-	 *
-	 * @return array The attachments.
-	 */
-	protected function get_block_attachments( $max_media ) {
-		// max media can't be negative or zero
-		if ( $max_media <= 0 ) {
-			return array();
-		}
-
-		$id = $this->wp_post->ID;
-
-		$media_ids = array();
-
-		// list post thumbnail first if this post has one
-		if ( \function_exists( 'has_post_thumbnail' ) && \has_post_thumbnail( $id ) ) {
-			$media_ids[] = \get_post_thumbnail_id( $id );
-		}
-
-		if ( $max_media > 0 ) {
-			$blocks = \parse_blocks( $this->wp_post->post_content );
-			$media_ids = self::get_media_ids_from_blocks( $blocks, $media_ids, $max_media );
-		}
-		$media_ids = \array_unique( $media_ids );
-
-		return \array_filter( \array_map( array( self::class, 'wp_attachment_to_activity_attachment' ), $media_ids ) );
-	}
-
-	/**
-	 * Get image attachments from the classic editor.
-	 * Note that audio/video attachments are only supported in the block editor.
-	 *
-	 * @param int $max_images The maximum number of images to return.
-	 *
-	 * @return array The attachments.
-	 */
-	protected function get_classic_editor_images( $max_images ) {
-		// max images can't be negative or zero
-		if ( $max_images <= 0 ) {
-			return array();
-		}
-
-		$id = $this->wp_post->ID;
-
-		$image_ids = array();
-
-		// list post thumbnail first if this post has one
-		if ( \function_exists( 'has_post_thumbnail' ) && \has_post_thumbnail( $id ) ) {
-			$image_ids[] = \get_post_thumbnail_id( $id );
-			--$max_images;
-		}
-
-		if ( $max_images > 0 ) {
-			$query = new \WP_Query(
-				array(
-					'post_parent' => $id,
-					'post_status' => 'inherit',
-					'post_type' => 'attachment',
-					'post_mime_type' => 'image',
-					'order' => 'ASC',
-					'orderby' => 'menu_order ID',
-					'posts_per_page' => $max_images,
-				)
-			);
-			foreach ( $query->get_posts() as $attachment ) {
-				if ( ! \in_array( $attachment->ID, $image_ids, true ) ) {
-					$image_ids[] = $attachment->ID;
-				}
-			}
-		}
-		$image_ids = \array_unique( $image_ids );
-
-		return \array_filter( \array_map( array( self::class, 'wp_attachment_to_activity_attachment' ), $image_ids ) );
-	}
-
-	/**
-	 * Recursively get media IDs from blocks.
-	 * @param array $blocks The blocks to search for media IDs
-	 * @param array $media_ids The media IDs to append new IDs to
-	 * @param int $max_media The maximum number of media to return.
-	 *
-	 * @return array The image IDs.
-	 */
-	protected static function get_media_ids_from_blocks( $blocks, $media_ids, $max_media ) {
-
-		foreach ( $blocks as $block ) {
-			// recurse into inner blocks
-			if ( ! empty( $block['innerBlocks'] ) ) {
-				$media_ids = self::get_media_ids_from_blocks( $block['innerBlocks'], $media_ids, $max_media );
-			}
-
-			switch ( $block['blockName'] ) {
-				case 'core/image':
-				case 'core/cover':
-				case 'core/audio':
-				case 'core/video':
-				case 'videopress/video':
-					if ( ! empty( $block['attrs']['id'] ) ) {
-						$media_ids[] = $block['attrs']['id'];
-					}
-					break;
-				case 'jetpack/slideshow':
-				case 'jetpack/tiled-gallery':
-					if ( ! empty( $block['attrs']['ids'] ) ) {
-						$media_ids = array_merge( $media_ids, $block['attrs']['ids'] );
-					}
-					break;
-				case 'jetpack/image-compare':
-					if ( ! empty( $block['attrs']['beforeImageId'] ) ) {
-						$media_ids[] = $block['attrs']['beforeImageId'];
-					}
-					if ( ! empty( $block['attrs']['afterImageId'] ) ) {
-						$media_ids[] = $block['attrs']['afterImageId'];
-					}
-					break;
-			}
-
-			// stop doing unneeded work
-			if ( count( $media_ids ) >= $max_media ) {
-				break;
-			}
-		}
-
-		// still need to slice it because one gallery could knock us over the limit
-		return array_slice( $media_ids, 0, $max_media );
-	}
-
-	/**
-	 * Converts a WordPress Attachment to an ActivityPub Attachment.
-	 *
-	 * @param int $id The Attachment ID.
-	 *
-	 * @return array The ActivityPub Attachment.
-	 */
-	public static function wp_attachment_to_activity_attachment( $id ) {
-		$attachment = array();
-		$mime_type = \get_post_mime_type( $id );
-		$mime_type_parts = \explode( '/', $mime_type );
-		// switching on image/audio/video
-		switch ( $mime_type_parts[0] ) {
-			case 'image':
-				$image_size = 'full';
-
-				/**
-				 * Filter the image URL returned for each post.
-				 *
-				 * @param array|false $thumbnail The image URL, or false if no image is available.
-				 * @param int         $id        The attachment ID.
-				 * @param string      $image_size The image size to retrieve. Set to 'full' by default.
-				 */
-				$thumbnail = apply_filters(
-					'activitypub_get_image',
-					self::get_image( $id, $image_size ),
-					$id,
-					$image_size
-				);
-
-				if ( $thumbnail ) {
-					$alt   = \get_post_meta( $id, '_wp_attachment_image_alt', true );
-					$image = array(
-						'type'      => 'Image',
-						'url'       => $thumbnail[0],
-						'mediaType' => $mime_type,
-					);
-
-					if ( $alt ) {
-						$image['name'] = $alt;
-					}
-					$attachment = $image;
-				}
-				break;
-
-			case 'audio':
-			case 'video':
-				$attachment = array(
-					'type'      => 'Document',
-					'mediaType' => $mime_type,
-					'url'       => \wp_get_attachment_url( $id ),
-					'name'      => \get_the_title( $id ),
-				);
-				$meta = wp_get_attachment_metadata( $id );
-				// height and width for videos
-				if ( isset( $meta['width'] ) && isset( $meta['height'] ) ) {
-					$attachment['width'] = $meta['width'];
-					$attachment['height'] = $meta['height'];
-				}
-				// @todo: add `icon` support for audio/video attachments. Maybe use post thumbnail?
-				break;
-		}
-
-		return \apply_filters( 'activitypub_attachment', $attachment, $id );
-	}
-
-	/**
-	 * Return details about an image attachment.
-	 *
-	 * @param int    $id         The attachment ID.
-	 * @param string $image_size The image size to retrieve. Set to 'full' by default.
-	 *
-	 * @return array|false Array of image data, or boolean false if no image is available.
-	 */
-	protected static function get_image( $id, $image_size = 'full' ) {
-		/**
-		 * Hook into the image retrieval process. Before image retrieval.
-		 *
-		 * @param int    $id         The attachment ID.
-		 * @param string $image_size The image size to retrieve. Set to 'full' by default.
-		 */
-		do_action( 'activitypub_get_image_pre', $id, $image_size );
-
-		$image = \wp_get_attachment_image_src( $id, $image_size );
-
-		/**
-		 * Hook into the image retrieval process. After image retrieval.
-		 *
-		 * @param int    $id         The attachment ID.
-		 * @param string $image_size The image size to retrieve. Set to 'full' by default.
-		 */
-		do_action( 'activitypub_get_image_post', $id, $image_size );
-
-		return $image;
+	public function get_label() {
+		return 'Built-In';
 	}
 
 	/**
@@ -452,105 +109,6 @@ class Post {
 		return $object_type;
 	}
 
-	/**
-	 * Returns a list of Mentions, used in the Post.
-	 *
-	 * @see https://docs.joinmastodon.org/spec/activitypub/#Mention
-	 *
-	 * @return array The list of Mentions.
-	 */
-	protected function get_cc() {
-		$cc = array();
-
-		$mentions = $this->get_mentions();
-		if ( $mentions ) {
-			foreach ( $mentions as $url ) {
-				$cc[] = $url;
-			}
-		}
-
-		return $cc;
-	}
-
-	/**
-	 * Returns a list of Tags, used in the Post.
-	 *
-	 * This includes Hash-Tags and Mentions.
-	 *
-	 * @return array The list of Tags.
-	 */
-	protected function get_tags() {
-		$tags = array();
-
-		$post_tags = \get_the_tags( $this->wp_post->ID );
-		if ( $post_tags ) {
-			foreach ( $post_tags as $post_tag ) {
-				$tag = array(
-					'type' => 'Hashtag',
-					'href' => \esc_url( \get_tag_link( $post_tag->term_id ) ),
-					'name' => esc_hashtag( $post_tag->name ),
-				);
-				$tags[] = $tag;
-			}
-		}
-
-		$mentions = $this->get_mentions();
-		if ( $mentions ) {
-			foreach ( $mentions as $mention => $url ) {
-				$tag = array(
-					'type' => 'Mention',
-					'href' => \esc_url( $url ),
-					'name' => \esc_html( $mention ),
-				);
-				$tags[] = $tag;
-			}
-		}
-
-		return $tags;
-	}
-
-	/**
-	 * Returns the content for the ActivityPub Item.
-	 *
-	 * The content will be generated based on the user settings.
-	 *
-	 * @return string The content.
-	 */
-	protected function get_content() {
-		global $post;
-
-		/**
-		 * Provides an action hook so plugins can add their own hooks/filters before AP content is generated.
-		 *
-		 * Example: if a plugin adds a filter to `the_content` to add a button to the end of posts, it can also remove that filter here.
-		 *
-		 * @param WP_Post $post The post object.
-		 */
-		do_action( 'activitypub_before_get_content', $post );
-
-		// phpcs:ignore WordPress.WP.GlobalVariablesOverride.Prohibited
-		$post    = $this->wp_post;
-		$content = $this->get_post_content_template();
-
-		// Register our shortcodes just in time.
-		Shortcodes::register();
-		// Fill in the shortcodes.
-		setup_postdata( $post );
-		$content = do_shortcode( $content );
-		wp_reset_postdata();
-
-		$content = \wpautop( $content );
-		$content = \preg_replace( '/[\n\r\t]/', '', $content );
-		$content = \trim( $content );
-
-		$content = \apply_filters( 'activitypub_the_content', $content, $post );
-
-		// Don't need these any more, should never appear in a post.
-		Shortcodes::unregister();
-
-		return $content;
-	}
-
 	/**
 	 * Gets the template to use to generate the content of the activitypub item.
 	 *
@@ -572,33 +130,4 @@ class Post {
 		return \get_option( 'activitypub_custom_post_content', ACTIVITYPUB_CUSTOM_POST_CONTENT );
 	}
 
-	/**
-	 * Helper function to get the @-Mentions from the post content.
-	 *
-	 * @return array The list of @-Mentions.
-	 */
-	protected function get_mentions() {
-		return apply_filters( 'activitypub_extract_mentions', array(), $this->wp_post->post_content, $this->wp_post );
-	}
-
-	/**
-	 * Returns the locale of the post.
-	 *
-	 * @return string The locale of the post.
-	 */
-	public function get_locale() {
-		$post_id = $this->wp_post->ID;
-		$lang    = \strtolower( \strtok( \get_locale(), '_-' ) );
-
-		/**
-		 * Filter the locale of the post.
-		 *
-		 * @param string  $lang    The locale of the post.
-		 * @param int     $post_id The post ID.
-		 * @param WP_Post $post    The post object.
-		 *
-		 * @return string The filtered locale of the post.
-		 */
-		return apply_filters( 'activitypub_post_locale', $lang, $post_id, $this->wp_post );
-	}
 }

templates/post-json.php

@@ -2,8 +2,10 @@
 // phpcs:ignore WordPress.WP.GlobalVariablesOverride.Prohibited
 $post = \get_post();
 
-$object = new \Activitypub\Transformer\Post( $post );
-$json = \array_merge( array( '@context' => \Activitypub\get_context() ), $object->to_object()->to_array() );
+$transformer = \Activitypub\Transformers_Manager::instance()->get_transformer( $post );
+$transformer->set_wp_post( $post );
+
+$json = \array_merge( array( '@context' => \Activitypub\get_context() ), $transformer->to_object()->to_array() );
 
 // filter output
 $json = \apply_filters( 'activitypub_json_post_array', $json );

templates/settings.php

@@ -201,26 +201,6 @@
 							</p>
 						</td>
 					</tr>
-					<tr>
-						<th scope="row"><?php \esc_html_e( 'Supported post types', 'activitypub' ); ?></th>
-						<td>
-							<fieldset>
-								<?php \esc_html_e( 'Enable ActivityPub support for the following post types:', 'activitypub' ); ?>
-
-								<?php $post_types = \get_post_types( array( 'public' => true ), 'objects' ); ?>
-								<?php $support_post_types = \get_option( 'activitypub_support_post_types', array( 'post', 'page' ) ) ? \get_option( 'activitypub_support_post_types', array( 'post', 'page' ) ) : array(); ?>
-								<ul>
-								<?php // phpcs:ignore WordPress.WP.GlobalVariablesOverride.Prohibited ?>
-								<?php foreach ( $post_types as $post_type ) { ?>
-									<li>
-										<input type="checkbox" id="activitypub_support_post_type_<?php echo \esc_attr( $post_type->name ); ?>" name="activitypub_support_post_types[]" value="<?php echo \esc_attr( $post_type->name ); ?>" <?php echo \checked( \in_array( $post_type->name, $support_post_types, true ) ); ?> />
-										<label for="activitypub_support_post_type_<?php echo \esc_attr( $post_type->name ); ?>"><?php echo \esc_html( $post_type->label ); ?></label>
-									</li>
-								<?php } ?>
-								</ul>
-							</fieldset>
-						</td>
-					</tr>
 					<tr>
 						<th scope="row">
 							<?php \esc_html_e( 'Hashtags (beta)', 'activitypub' ); ?>
@@ -236,6 +216,93 @@
 
 			<?php \do_settings_fields( 'activitypub', 'activity' ); ?>
 		</div>
+		
+		<!-- OUR FORK HERE -->
+		<div class="box">
+		<h3><?php \esc_html_e( 'Enable ActivityPub support for post type', 'activitypub' ); ?></h3>
+
+		<table class="form-table">
+				<tbody>
+					<tr>
+						<th scope="row">
+							<?php \esc_html_e( 'Mapping', 'activitypub' ); ?>
+						</th>
+						<td>
+						<?php \esc_html_e( 'Enable ActivityPub support for a certain post type by selecting one of the available ActivityPub transformers.', 'activitypub' ); ?>
+
+				<?php $all_public_post_types = \get_post_types( array( 'public' => true ), 'objects' );
+				$transformer_mapping =  \get_option( 'activitypub_transformer_mapping', array( 'default' => 'note' ) );
+
+				$all_public_post_type_names = array_map(function ($object) {
+					return $object->name;
+				}, $all_public_post_types);
+
+				$transformer_manager = \Activitypub\Transformers_Manager::instance();
+				$transformers = $transformer_manager->get_transformers();
+
+				?>
+
+				
+				<script>
+					// TODO Probably we should use checkboxes and not select and make this less buggy and insert the js at the right place.
+					document.addEventListener('DOMContentLoaded', function () {
+						var radioGroups = {};
+
+						var radioButtons = document.querySelectorAll('input[type="radio"]');
+						
+						radioButtons.forEach(function (radioButton) {
+							radioButton.addEventListener('click', function () {
+								var name = this.name;
+
+								if (!radioGroups[name]) {
+									radioGroups[name] = this;
+								} else {
+									radioGroups[name].checked = false;
+									radioGroups[name] = this;
+								}
+							});
+						});
+					});
+				</script>
+
+				<table>
+					<thead>
+					<tr>
+						<th></th>
+						<?php
+						// Generate column headers based on transformer objects
+						foreach ($transformers as $transformer) {
+							echo '<th>' . htmlspecialchars($transformer->get_label()) . '</th>';
+						}
+						?>
+					</tr>
+					</thead>
+					<tbody>
+					<?php
+					// Generate rows based on post types and transformers
+					foreach ($all_public_post_types as $post_type) {
+						echo '<tr>';
+						echo '<td><strong>' . htmlspecialchars($post_type->label) . '</strong></td>';
+						// Generate radio inputs for each transformer, considering support for the post type
+						foreach ($transformers as $transformer) {
+							$disabled_attribute = $transformer->supports_post_type( $post_type->name ) ? '' : ' disabled';
+							$is_selected = ( is_array( $transformer_mapping ) && isset( $transformer_mapping[ $post_type->name ] ) && $transformer_mapping[ $post_type->name ] === $transformer->get_name() ) ? ' checked ' : '';	
+							echo '<td><input type="radio" name="activitypub_transformer_mapping[' . $post_type->name . ']" value="' . $transformer->get_name() . '"' . $is_selected . $disabled_attribute . '></td>';
+						}
+
+						echo '</tr>';
+					}
+					?>
+					</tbody>
+				</table>
+
+			
+				</td>
+			</tr>
+				</tbody>
+				</table>
+		</div>
+		<!-- OUR FORK ENDS HERE -->
 
 		<div class="box">
 			<h3><?php \esc_html_e( 'Server', 'activitypub' ); ?></h3>

tests/test-class-activitypub-activity.php

@@ -16,8 +16,9 @@ class Test_Activitypub_Activity extends WP_UnitTestCase {
 			},
 			10
 		);
-
-		$activitypub_post = \Activitypub\Transformer\Post::transform( get_post( $post ) )->to_object();
+		
+		$wp_post = get_post( $post );
+		$activitypub_post = \Activitypub\Transformers_Manager::get_transforemr( $wp_post )->transform( $wp_post )->to_object();
 
 		$activitypub_activity = new \Activitypub\Activity\Activity();
 		$activitypub_activity->set_type( 'Create' );

tests/test-class-activitypub-post.php

@@ -10,13 +10,13 @@ class Test_Activitypub_Post extends WP_UnitTestCase {
 
 		$permalink = \get_permalink( $post );
 
-		$activitypub_post = \Activitypub\Transformer\Post::transform( get_post( $post ) )->to_object();
+		$activitypub_post = \Activitypub\Transformers_Manager::get_transformer( get_post( $post ) )->transform( get_post( $post ) )->to_object();
 
 		$this->assertEquals( $permalink, $activitypub_post->get_id() );
 
 		\wp_trash_post( $post );
 
-		$activitypub_post = \Activitypub\Transformer\Post::transform( get_post( $post ) )->to_object();
+		$activitypub_post = \Activitypub\Transformers_Manager::get_transformer( get_post( $post ) )->transform( get_post( $post ) )->to_object();
 
 		$this->assertEquals( $permalink, $activitypub_post->get_id() );
 

tests/test-class-activitypub-rest-post-signature-verification.php

@@ -10,7 +10,7 @@ class Test_Activitypub_Signature_Verification extends WP_UnitTestCase {
 			)
 		);
 		$remote_actor = \get_author_posts_url( 2 );
-		$activitypub_post = \Activitypub\Transformer\Post::transform( get_post( $post ) )->to_object();
+		$activitypub_post = \Activitypub\Transformers_Manager::get_transformer( get_post( $post ) )->transform( get_post( $post ) )->to_object();
 		$activitypub_activity = new Activitypub\Activity\Activity( 'Create' );
 		$activitypub_activity->set_type( 'Create' );
 		$activitypub_activity->set_object( $activitypub_post );
@@ -82,7 +82,7 @@ class Test_Activitypub_Signature_Verification extends WP_UnitTestCase {
 		);
 		$remote_actor = \get_author_posts_url( 2 );
 		$remote_actor_inbox = Activitypub\get_rest_url_by_path( '/inbox' );
-		$activitypub_post = \Activitypub\Transformer\Post::transform( \get_post( $post ) )->to_object();
+		$activitypub_post = \Activitypub\Transformers_Manager::get_transformer( get_post( $post ) )->transform( get_post( $post ) )->to_object();
 		$activitypub_activity = new Activitypub\Activity\Activity();
 		$activitypub_activity->set_type( 'Create' );
 		$activitypub_activity->set_object( $activitypub_post );