Improved recipient handling for clarity and added better inbox support (#2210)

Author: pfefferle

.github/changelog/2210-from-description

@@ -0,0 +1,4 @@
+Significance: minor
+Type: changed
+
+Improved recipient handling for clarity and improved visibility handling of activities.

includes/functions.php

@@ -525,40 +525,60 @@ function extract_recipients_from_activity( $data ) {
 	$recipient_items = array();
 
 	foreach ( array( 'to', 'bto', 'cc', 'bcc', 'audience' ) as $i ) {
-		if ( array_key_exists( $i, $data ) ) {
-			if ( is_array( $data[ $i ] ) ) {
-				$recipient = $data[ $i ];
-			} else {
-				$recipient = array( $data[ $i ] );
-			}
-			$recipient_items = array_merge( $recipient_items, $recipient );
-		}
-
-		if ( is_array( $data['object'] ) && array_key_exists( $i, $data['object'] ) ) {
-			if ( is_array( $data['object'][ $i ] ) ) {
-				$recipient = $data['object'][ $i ];
-			} else {
-				$recipient = array( $data['object'][ $i ] );
-			}
-			$recipient_items = array_merge( $recipient_items, $recipient );
-		}
+		$recipient_items = \array_merge( $recipient_items, extract_recipients_from_activity_property( $i, $data ) );
 	}
 
+	return \array_unique( $recipient_items );
+}
+
+/**
+ * Extract recipient URLs from a specific property of an Activity object.
+ *
+ * @param string $property The property to extract recipients from (e.g., 'to', 'cc').
+ * @param array  $data     The Activity object as array.
+ *
+ * @return array The list of user URLs.
+ */
+function extract_recipients_from_activity_property( $property, $data ) {
 	$recipients = array();
 
-	// Flatten array.
-	foreach ( $recipient_items as $recipient ) {
-		if ( is_array( $recipient ) ) {
-			// Check if recipient is an object.
-			if ( array_key_exists( 'id', $recipient ) ) {
-				$recipients[] = $recipient['id'];
-			}
-		} else {
-			$recipients[] = $recipient;
-		}
+	if ( ! empty( $data[ $property ] ) ) {
+		$recipients = $data[ $property ];
+	} elseif ( ! empty( $data['object'][ $property ] ) ) {
+		$recipients = $data['object'][ $property ];
+	}
+
+	$recipients = \array_map( '\Activitypub\object_to_uri', (array) $recipients );
+
+	return \array_unique( \array_filter( $recipients ) );
+}
+
+/**
+ * Determine the visibility of the activity based on its recipients.
+ *
+ * @param array $activity The activity data.
+ *
+ * @return string The visibility level: 'public', 'private', or 'direct'.
+ */
+function get_activity_visibility( $activity ) {
+	// Set default visibility for specific activity types.
+	if ( ! empty( $activity['type'] ) && in_array( $activity['type'], array( 'Accept', 'Delete', 'Follow', 'Reject', 'Undo' ), true ) ) {
+		return ACTIVITYPUB_CONTENT_VISIBILITY_PRIVATE;
+	}
+
+	// Check 'to' field for public visibility.
+	$to = extract_recipients_from_activity_property( 'to', $activity );
+	if ( ! empty( array_intersect( $to, ACTIVITYPUB_PUBLIC_AUDIENCE_IDENTIFIERS ) ) ) {
+		return ACTIVITYPUB_CONTENT_VISIBILITY_PUBLIC;
+	}
+
+	// Check 'cc' field for quiet public visibility.
+	$cc = extract_recipients_from_activity_property( 'cc', $activity );
+	if ( ! empty( array_intersect( $cc, ACTIVITYPUB_PUBLIC_AUDIENCE_IDENTIFIERS ) ) ) {
+		return ACTIVITYPUB_CONTENT_VISIBILITY_QUIET_PUBLIC;
 	}
 
-	return array_unique( $recipients );
+	return ACTIVITYPUB_CONTENT_VISIBILITY_PRIVATE;
 }
 
 /**
@@ -696,7 +716,7 @@ function url_to_commentid( $url ) {
  *
  * @param array|string $data The ActivityPub object.
  *
- * @return string The URI of the ActivityPub object
+ * @return string The URI of the ActivityPub object.
  */
 function object_to_uri( $data ) {
 	// Check whether it is already simple.

includes/handler/class-create.php

@@ -9,7 +9,7 @@
 
 use Activitypub\Collection\Interactions;
 
-use function Activitypub\is_activity_public;
+use function Activitypub\get_activity_visibility;
 use function Activitypub\is_activity_reply;
 use function Activitypub\is_self_ping;
 use function Activitypub\object_id_to_comment;
@@ -22,19 +22,8 @@ class Create {
 	 * Initialize the class, registering WordPress hooks.
 	 */
 	public static function init() {
-		\add_action(
-			'activitypub_inbox_create',
-			array( self::class, 'handle_create' ),
-			10,
-			3
-		);
-
-		\add_filter(
-			'activitypub_validate_object',
-			array( self::class, 'validate_object' ),
-			10,
-			3
-		);
+		\add_action( 'activitypub_inbox_create', array( self::class, 'handle_create' ), 10, 3 );
+		\add_filter( 'activitypub_validate_object', array( self::class, 'validate_object' ), 10, 3 );
 	}
 
 	/**
@@ -47,7 +36,7 @@ public static function init() {
 	public static function handle_create( $activity, $user_id, $activity_object = null ) {
 		// Check if Activity is public or not.
 		if (
-			! is_activity_public( $activity ) ||
+			ACTIVITYPUB_CONTENT_VISIBILITY_PRIVATE === get_activity_visibility( $activity ) ||
 			! is_activity_reply( $activity )
 		) {
 			return;

includes/rest/class-inbox-controller.php

@@ -149,23 +149,9 @@ public function create_item( $request ) {
 			 */
 			do_action( 'activitypub_rest_inbox_disallowed', $data, null, $type, $activity );
 		} else {
-			$recipients = extract_recipients_from_activity( $data );
-
-			foreach ( $recipients as $recipient ) {
-				if ( ! is_same_domain( $recipient ) ) {
-					continue;
-				}
-
-				$user_id = Actors::get_id_by_various( $recipient );
-
-				if ( \is_wp_error( $user_id ) ) {
-					continue;
-				}
-
-				if ( ! user_can_activitypub( $user_id ) ) {
-					continue;
-				}
+			$recipients = $this->get_local_recipients( $data );
 
+			foreach ( $recipients as $user_id ) {
 				// Check user-specific blocks for this recipient.
 				if ( Moderation::activity_is_blocked_for_user( $activity, $user_id ) ) {
 					/**
@@ -288,4 +274,37 @@ public function get_item_schema() {
 
 		return $this->add_additional_fields_schema( $this->schema );
 	}
+
+	/**
+	 * Extract recipients from the given Activity.
+	 *
+	 * @param array $activity The activity data.
+	 *
+	 * @return array An array of user IDs who are the recipients of the activity.
+	 */
+	private function get_local_recipients( $activity ) {
+		$recipients = extract_recipients_from_activity( $activity );
+		$user_ids   = array();
+
+		foreach ( $recipients as $recipient ) {
+
+			if ( ! is_same_domain( $recipient ) ) {
+				continue;
+			}
+
+			$user_id = Actors::get_id_by_resource( $recipient );
+
+			if ( \is_wp_error( $user_id ) ) {
+				continue;
+			}
+
+			if ( ! user_can_activitypub( $user_id ) ) {
+				continue;
+			}
+
+			$user_ids[] = $user_id;
+		}
+
+		return $user_ids;
+	}
 }