From eb58862777cdfc02e0574dcaf11140c2a5dbf12b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Menrath?= <andre.menrath@posteo.de>
Date: Sat, 23 Dec 2023 09:52:03 +0100
Subject: [PATCH] Announce all posts through the application actor

---
 includes/class-activity-dispatcher.php | 32 ++++++++++++++++++++------
 includes/collection/class-users.php    |  6 +++++
 includes/table/class-followers.php     |  2 +-
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/includes/class-activity-dispatcher.php b/includes/class-activity-dispatcher.php
index 6bb6a04..d245c9b 100644
--- a/includes/class-activity-dispatcher.php
+++ b/includes/class-activity-dispatcher.php
@@ -10,6 +10,7 @@ use Activitypub\Transformer\Factory;
 use Activitypub\Transformer\Post;
 use Activitypub\Transformer\Comment;
 
+use function Activitypub\get_rest_url_by_path;
 use function Activitypub\is_single_user;
 use function Activitypub\is_user_disabled;
 use function Activitypub\safe_remote_post;
@@ -49,8 +50,10 @@ class Activity_Dispatcher {
 
 		if ( is_single_user() ) {
 			self::send_activity( $wp_object, $type, Users::BLOG_USER_ID );
+			self::send_announce( $wp_object, $type, Users::APPLICATION_USER_ID );
 		} else {
-			self::send_announce( $wp_object, $type );
+			self::send_announce( $wp_object, $type, Users::BLOG_USER_ID );
+			self::send_announce( $wp_object, $type, Users::APPLICATION_USER_ID );
 		}
 	}
 
@@ -88,21 +91,36 @@ class Activity_Dispatcher {
 	 *
 	 * @return void
 	 */
-	public static function send_announce( $wp_object, $type ) {
+	public static function send_announce( $wp_object, $type, $user_id = null ) {
 		if ( ! in_array( $type, array( 'Create', 'Update' ), true ) ) {
 			return;
 		}
 
-		if ( is_user_disabled( Users::BLOG_USER_ID ) ) {
+		$transformer = Factory::instance()->get_transformer( $wp_object );
+
+		if ( null !== $user_id && Users::APPLICATION_USER_ID !== $user_id ) {
+			$transformer->change_wp_user_id( $user_id );
+		}
+
+		if ( ! $user_id ) {
+			$user_id  = $transformer->get_wp_user_id();
+		}
+
+		if ( is_user_disabled( $user_id ) ) {
 			return;
 		}
 
-		$transformer = Factory::instance()->get_transformer( $wp_object );
-		$transformer->change_wp_user_id( Users::BLOG_USER_ID );
-
-		$user_id  = $transformer->get_wp_user_id();
 		$activity = $transformer->to_activity( 'Announce' );
 
+		// TODO: properly fix this for the instance-to-instance federation with Mobilizon.
+		// Error:
+		//      Failed to map identity from signature (payload actor mismatch)
+		//  	key_id=http://wp.lan/wp-json/activitypub/1.0/application, actor=http://wp.lan/@blog
+        // Of course, the announce must be sent as the Application actor because he also signed it!
+		if ( Users::APPLICATION_USER_ID === $user_id ) {
+			$activity->set_actor( get_rest_url_by_path( 'application' ) );
+		}
+
 		self::send_activity_to_inboxes( $activity, $user_id );
 	}
 
diff --git a/includes/collection/class-users.php b/includes/collection/class-users.php
index ad94297..8f279fb 100644
--- a/includes/collection/class-users.php
+++ b/includes/collection/class-users.php
@@ -7,6 +7,7 @@ use Activitypub\Model\User;
 use Activitypub\Model\Blog_User;
 use Activitypub\Model\Application_User;
 
+use function Activitypub\get_rest_url_by_path;
 use function Activitypub\url_to_authorid;
 use function Activitypub\is_user_disabled;
 
@@ -176,6 +177,11 @@ class Users {
 					return self::get_by_id( self::BLOG_USER_ID );
 				}
 
+				// check for application actor
+				if ( self::normalize_url( get_rest_url_by_path( 'application' ) ) === self::normalize_url( $resource ) ) {
+					return self::get_by_id( self::APPLICATION_USER_ID );
+				}
+
 				return new WP_Error(
 					'activitypub_no_user_found',
 					\__( 'User not found', 'activitypub' ),
diff --git a/includes/table/class-followers.php b/includes/table/class-followers.php
index df9747b..76b1f83 100644
--- a/includes/table/class-followers.php
+++ b/includes/table/class-followers.php
@@ -16,7 +16,7 @@ class Followers extends WP_List_Table {
 
 	public function __construct() {
 		if ( get_current_screen()->id === 'settings_page_activitypub' ) {
-			$this->user_id = Users::BLOG_USER_ID;
+			$this->user_id = Users::APPLICATION_USER_ID;
 		} else {
 			$this->user_id = \get_current_user_id();
 		}