From 3ae8f8213ff9091e1674f90e1fcca3b98dd08056 Mon Sep 17 00:00:00 2001
From: Diogo Peralta Cordeiro <mail@diogo.site>
Date: Fri, 11 Feb 2022 11:39:25 +0000
Subject: [PATCH] [GROUP] Notifity group subscribers of new activity concerning
 the group

---
 components/Group/Group.php               | 23 +++++++++++++++++
 components/Notification/Notification.php | 32 +++++++++++++++++++++---
 plugins/ActivityPub/ActivityPub.php      |  8 +++++-
 3 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/components/Group/Group.php b/components/Group/Group.php
index fcff9bb481..89bd8760fd 100644
--- a/components/Group/Group.php
+++ b/components/Group/Group.php
@@ -22,6 +22,8 @@ declare(strict_types = 1);
 namespace Component\Group;
 
 use App\Core\Event;
+use App\Entity\Activity;
+use Component\Notification\Notification;
 use function App\Core\I18n\_m;
 use App\Core\Modules\Component;
 use App\Core\Router\RouteLoader;
@@ -46,6 +48,27 @@ class Group extends Component
         return Event::next;
     }
 
+    /**
+     * Enqueues a notification for an Actor (such as person or group) which means
+     * it shows up in their home feed and such.
+     * @param Actor $sender
+     * @param Activity $activity
+     * @param array $targets
+     * @param string|null $reason
+     * @return bool
+     */
+    public function onNewNotificationWithTargets(Actor $sender, Activity $activity, array $targets = [], ?string $reason = null): bool
+    {
+        foreach($targets as $target) {
+            if ($target->isGroup()) {
+                // The Group announces to its subscribers
+                Notification::notify($target, $activity, $target->getSubscribers(), $reason);
+            }
+        }
+
+        return Event::next;
+    }
+
     /**
      * Add an <a href=group_settings> to the profile card for groups, if the current actor can access them
      */
diff --git a/components/Notification/Notification.php b/components/Notification/Notification.php
index 07b0bf74dc..58a462a6bc 100644
--- a/components/Notification/Notification.php
+++ b/components/Notification/Notification.php
@@ -23,6 +23,7 @@ namespace Component\Notification;
 
 use App\Core\DB\DB;
 use App\Core\Event;
+use App\Util\Exception\ServerException;
 use function App\Core\I18n\_m;
 use App\Core\Log;
 use App\Core\Modules\Component;
@@ -36,13 +37,24 @@ use Component\Notification\Controller\Feed;
 
 class Notification extends Component
 {
+    /**
+     * @param RouteLoader $m
+     * @return bool
+     */
     public function onAddRoute(RouteLoader $m): bool
     {
         $m->connect('feed_notifications', '/feed/notifications', [Feed::class, 'notifications']);
         return Event::next;
     }
 
-    public function onCreateDefaultFeeds(int $actor_id, LocalUser $user, int &$ordering)
+    /**
+     * @param int $actor_id
+     * @param LocalUser $user
+     * @param int $ordering
+     * @return bool
+     * @throws ServerException
+     */
+    public function onCreateDefaultFeeds(int $actor_id, LocalUser $user, int &$ordering): bool
     {
         DB::persist(\App\Entity\Feed::create([
             'actor_id' => $actor_id,
@@ -55,21 +67,33 @@ class Notification extends Component
     }
 
     /**
-     * Enqueues a notification for an Actor (user or group) which means
+     * Enqueues a notification for an Actor (such as person or group) which means
      * it shows up in their home feed and such.
+     * @param Actor $sender
+     * @param Activity $activity
+     * @param array $ids_already_known
+     * @param string|null $reason
+     * @return bool
      */
     public function onNewNotification(Actor $sender, Activity $activity, array $ids_already_known = [], ?string $reason = null): bool
     {
         $targets = $activity->getNotificationTargets(ids_already_known: $ids_already_known, sender_id: $sender->getId());
-        $this->notify($sender, $activity, $targets, $reason);
+        if (Event::handle('NewNotificationWithTargets', [$sender, $activity, $targets, $reason]) === Event::next) {
+            self::notify($sender, $activity, $targets, $reason);
+        }
 
         return Event::next;
     }
 
     /**
      * Bring given Activity to Targets's attention
+     * @param Actor $sender
+     * @param Activity $activity
+     * @param array $targets
+     * @param string|null $reason
+     * @return bool
      */
-    public function notify(Actor $sender, Activity $activity, array $targets, ?string $reason = null): bool
+    public static function notify(Actor $sender, Activity $activity, array $targets, ?string $reason = null): bool
     {
         $remote_targets = [];
         foreach ($targets as $target) {
diff --git a/plugins/ActivityPub/ActivityPub.php b/plugins/ActivityPub/ActivityPub.php
index 1c438cacb6..951318e344 100644
--- a/plugins/ActivityPub/ActivityPub.php
+++ b/plugins/ActivityPub/ActivityPub.php
@@ -32,6 +32,7 @@ declare(strict_types = 1);
 
 namespace Plugin\ActivityPub;
 
+use ActivityPhp\Type;
 use App\Core\DB\DB;
 use App\Core\Event;
 use App\Core\HTTPClient;
@@ -269,7 +270,12 @@ class ActivityPub extends Plugin
         //$to_failed = [];
         foreach ($to_addr as $inbox => $dummy) {
             try {
-                $res = self::postman($sender, Model::toJson($activity), $inbox);
+                $data = Model::toJson($activity);
+                if ($sender->isGroup()) {
+                    // When the sender is a group, we have to wrap it in an Announce activity
+                    $data = Type::create('Announce', ['object' => $data])->toJson();
+                }
+                $res = self::postman($sender, $data, $inbox);
 
                 // accumulate errors for later use, if needed
                 $status_code = $res->getStatusCode();