Add replies collection

activitypub.php

@@ -37,7 +37,7 @@
 \defined( 'ACTIVITYPUB_AUTHORIZED_FETCH' ) || \define( 'ACTIVITYPUB_AUTHORIZED_FETCH', false );
 \defined( 'ACTIVITYPUB_DISABLE_REWRITES' ) || \define( 'ACTIVITYPUB_DISABLE_REWRITES', false );
 \defined( 'ACTIVITYPUB_DISABLE_INCOMING_INTERACTIONS' ) || \define( 'ACTIVITYPUB_DISABLE_INCOMING_INTERACTIONS', false );
-// Disable reactions like `Like` and `Accounce` by default
+// Disable reactions like `Like` and `Announce` by default
 \defined( 'ACTIVITYPUB_DISABLE_REACTIONS' ) || \define( 'ACTIVITYPUB_DISABLE_REACTIONS', true );
 \defined( 'ACTIVITYPUB_DISABLE_OUTGOING_INTERACTIONS' ) || \define( 'ACTIVITYPUB_DISABLE_OUTGOING_INTERACTIONS', false );
 \defined( 'ACTIVITYPUB_SHARED_INBOX_FEATURE' ) || \define( 'ACTIVITYPUB_SHARED_INBOX_FEATURE', false );

includes/activity/class-activity.php

@@ -90,6 +90,21 @@ class Activity extends Base_Object {
  */
  protected $result;
 
+ /**
+ * Identifies a Collection containing objects considered to be responses
+ * to this object.
+ * WordPress has a strong core system of approving replies. We only include
+ * approved replies here.
+ *
+ * @see https://www.w3.org/TR/activitystreams-vocabulary/#dfn-replies
+ *
+ * @var array
+ * | ObjectType
+ * | Link
+ * | null
+ */
+ protected $replies;
+
  /**
  * An indirect object of the activity from which the
  * activity is directed.

includes/collection/class-followers.php

@@ -111,7 +111,7 @@ public static function get_follower( $user_id, $actor ) {
  }
 
  /**
- * Get a Follower by Actor indepenent from the User.
+ * Get a Follower by Actor independent from the User.
  *
  * @param string $actor The Actor URL.
  *

includes/collection/class-replies.php

@@ -0,0 +1,175 @@
+<?php
+namespace Activitypub\Collection;
+
+use WP_Post;
+use WP_Comment;
+use WP_Error;
+
+use function Activitypub\is_local_comment;
+use function Activitypub\get_rest_url_by_path;
+
+/**
+ * Class containing code for getting replies Collections and CollectionPages of posts and comments.
+ */
+class Replies {
+ /**
+ * Build base arguments for fetching the comments of either a WordPress post or comment.
+ *
+ * @param WP_Post|WP_Comment $wp_object
+ */
+ private static function build_args( $wp_object ) {
+ $args = array(
+ 'status' => 'approve',
+ 'orderby' => 'comment_date_gmt',
+ 'order' => 'ASC',
+ );
+
+ if ( $wp_object instanceof WP_Post ) {
+ $args['parent'] = 0; // TODO: maybe this is unnecessary.
+ $args['post_id'] = $wp_object->ID;
+ } elseif ( $wp_object instanceof WP_Comment ) {
+ $args['parent'] = $wp_object->comment_ID;
+ } else {
+ return new WP_Error();
+ }
+
+ return $args;
+ }
+
+ /**
+ * Adds pagination args comments query.
+ *
+ * @param array $args Query args built by self::build_args.
+ * @param int $page The current pagination page.
+ * @param int $comments_per_page The number of comments per page.
+ */
+ private static function add_pagination_args( $args, $page, $comments_per_page ) {
+ $args['number'] = $comments_per_page;
+
+ $offset = intval( $page ) * $comments_per_page;
+ $args['offset'] = $offset;
+
+ return $args;
+ }
+
+
+ /**
+ * Get the replies collections ID.
+ *
+ * @param WP_Post|WP_Comment $wp_object
+ *
+ * @return string The rest URL of the replies collection.
+ */
+ private static function get_replies_id( $wp_object ) {
+ if ( $wp_object instanceof WP_Post ) {
+ return get_rest_url_by_path( sprintf( 'posts/%d/replies', $wp_object->ID ) );
+ } elseif ( $wp_object instanceof WP_Comment ) {
+ return get_rest_url_by_path( sprintf( 'comments/%d/replies', $wp_object->comment_ID ) );
+ } else {
+ return new WP_Error();
+ }
+ }
+
+ /**
+ * Get the replies collection.
+ *
+ * @param WP_Post|WP_Comment $wp_object
+ * @param int $page
+ *
+ * @return array An associative array containing the replies collection without JSON-LD context.
+ */
+ public static function get_collection( $wp_object ) {
+ $id = self::get_replies_id( $wp_object );
+
+ if ( ! $id ) {
+ return null;
+ }
+
+ $replies = array(
+ 'id' => $id,
+ 'type' => 'Collection',
+ );
+
+ $replies['first'] = self::get_collection_page( $wp_object, 0, $replies['id'] );
+
+ return $replies;
+ }
+
+ /**
+ * Get the ActivityPub ID's from a list of comments.
+ *
+ * It takes only federated/non-local comments into account, others also do not have an
+ * ActivityPub ID available.
+ *
+ * @param WP_Comment[] $comments The comments to retrieve the ActivityPub ids from.
+ *
+ * @return string[] A list of the ActivityPub ID's.
+ */
+ private static function get_activitypub_comment_ids( $comments ) {
+ $comment_ids = array();
+ // Only add external comments from the fediverse.
+ // Maybe use the Comment class more and the function is_local_comment etc.
+ foreach ( $comments as $comment ) {
+ if ( is_local_comment( $comment ) ) {
+ continue;
+ }
+ $comment_meta = \get_comment_meta( $comment->comment_ID );
+ if ( ! empty( $comment_meta['source_url'][0] ) ) {
+ $comment_ids[] = $comment_meta['source_url'][0];
+ } elseif ( ! empty( $comment_meta['source_id'][0] ) ) {
+ $comment_ids[] = $comment_meta['source_id'][0];
+ }
+ }
+ return $comment_ids;
+ }
+
+ /**
+ * Returns a replies collection page as an associative array.
+ *
+ * @link https://www.w3.org/TR/activitystreams-vocabulary/#dfn-collectionpage
+ *
+ * @param WP_Post|WP_Comment $wp_object The post of comment the replies are for.
+ * @param int $page The current pagination page.
+ * @param string $part_of The collection id/url the returned CollectionPage belongs to.
+ *
+ * @return array A CollectionPage as an associative array.
+ */
+ public static function get_collection_page( $wp_object, $page, $part_of = null ) {
+ // Build initial arguments for fetching approved comments.
+ $args = self::build_args( $wp_object );
+
+ // Retrieve the partOf if not already given.
+ $part_of = $part_of ?? self::get_replies_id( $wp_object );
+
+ // If the collection page does not exist.
+ if ( is_wp_error( $args ) || is_wp_error( $part_of ) ) {
+ return null;
+ }
+
+ // Get to total replies count.
+ $total_replies = get_comments( array_merge( $args, array( 'count' => true ) ) );
+
+ // Modify query args to retrieve paginated results.
+ $comments_per_page = get_option( 'comments_per_page' );
+
+ // Fetch internal and external comments for current page.
+ $comments = get_comments( self::add_pagination_args( $args, $page, $comments_per_page ) );
+
+ // Get the ActivityPub ID's of the comments, without out local-only comments.
+ $comment_ids = self::get_activitypub_comment_ids( $comments );
+
+ // Build the associative CollectionPage array.
+ $collection_page = array(
+ 'id' => \add_query_arg( 'page', $page, $part_of ),
+ 'type' => 'CollectionPage',
+ 'partOf' => $part_of,
+ 'items' => $comment_ids,
+ );
+
+ if ( $total_replies / $comments_per_page > $page + 1 ) {
+ $collection_page['next'] = \add_query_arg( 'page', $page + 1, $part_of );
+ }
+
+ return $collection_page;
+ }
+}

includes/rest/class-collection.php

@@ -6,7 +6,10 @@
 use Activitypub\Activity\Actor;
 use Activitypub\Activity\Base_Object;
 use Activitypub\Collection\Users as User_Collection;
+use Activitypub\Collection\Replies;
+
 use Activitypub\Transformer\Factory;
+use WP_Error;
 
 use function Activitypub\esc_hashtag;
 use function Activitypub\is_single_user;
@@ -69,6 +72,71 @@ public static function register_routes() {
  ),
  )
  );
+
+ \register_rest_route(
+ ACTIVITYPUB_REST_NAMESPACE,
+ '/(?P<type>[\w\-\.]+)s/(?P<id>[\w\-\.]+)/replies',
+ array(
+ array(
+ 'methods' => WP_REST_Server::READABLE,
+ 'callback' => array( self::class, 'replies_get' ),
+ 'args' => self::request_parameters_for_replies(),
+ 'permission_callback' => '__return_true',
+ ),
+ )
+ );
+ }
+
+ /**
+ * The endpoint for replies collections
+ *
+ * @param WP_REST_Request $request The request object.
+ *
+ * @return WP_REST_Response The response object.
+ */
+ public static function replies_get( $request ) {
+ $type = $request->get_param( 'type' );
+
+ // Get the WordPress object of that "owns" the requested replies.
+ if ( 'post' === $type ) {
+ $wp_object = get_post( $request->get_param( 'id' ) );
+ } elseif ( 'comment' === $type ) {
+ $wp_object = get_comment( $request->get_param( 'id' ) );
+ }
+
+ if ( ! isset( $wp_object ) || is_wp_error( $wp_object ) ) {
+ return new WP_Error(
+ 'activitypub_replies_collection_does_not_exist',
+ \sprintf(
+ // translators: %s: The type (post, comment, etc.) for which no replies collection exists.
+ \__(
+ 'No reply collection exists for the type %s.'
+ ),
+ $type
+ )
+ );
+ }
+
+ $page = intval( $request->get_param( 'page' ) );
+
+ // If the request parameter page is present get the CollectionPage otherwise the replies collection.
+ if ( isset( $page ) ) {
+ $response = Replies::get_collection_page( $wp_object, $page );
+ } else {
+ $response = Replies::get_collection( $wp_object );
+ }
+
+ if ( is_wp_error( $response ) ) {
+ return $response;
+ }
+
+ // Add ActivityPub Context.
+ $response = array_merge(
+ array( '@context' => Base_Object::JSON_LD_CONTEXT ),
+ $response
+ );
+
+ return new WP_REST_Response( $response, 200 );
  }
 
  /**
@@ -225,4 +293,25 @@ public static function request_parameters() {
 
  return $params;
  }
+
+ /**
+ * The supported parameters
+ *
+ * @return array list of parameters
+ */
+ public static function request_parameters_for_replies() {
+ $params = array();
+
+ $params['type'] = array(
+ 'required' => true,
+ 'type' => 'string',
+ );
+
+ $params['id'] = array(
+ 'required' => true,
+ 'type' => 'string',
+ );
+
+ return $params;
+ }
 }

includes/transformer/class-base.php

@@ -1,12 +1,13 @@
 <?php
 namespace Activitypub\Transformer;
 
-use WP_Error;
 use WP_Post;
 use WP_Comment;
 
 use Activitypub\Activity\Activity;
 use Activitypub\Activity\Base_Object;
+use Activitypub\Collection\Replies;
+
 
 /**
  * WordPress Base Transformer
@@ -108,6 +109,16 @@ public function to_activity( $type ) {
  return $activity;
  }
 
+ abstract protected function get_id();
+
+ /**
+ * Get the replies Collection.
+ */
+ public function get_replies() {
+ $replies = Replies::get_collection( $this->wp_object, $this->get_id() );
+ return $replies;
+ }
+
  /**
  * Returns the ID of the WordPress Object.
  *

includes/transformer/class-post.php

@@ -88,7 +88,7 @@ public function to_object() {
  *
  * @return string The Posts ID.
  */
- public function get_id() {
+ protected function get_id() {
  return $this->get_url();
  }