From fe087b221743824cd73ffeef82f68ae37d0d6215 Mon Sep 17 00:00:00 2001
From: Diogo Peralta Cordeiro <mail@diogo.site>
Date: Sun, 2 Jan 2022 22:24:04 +0000
Subject: [PATCH] [PLUGIN][ActivityPub] Accept Undo Follow

---
 plugins/ActivityPub/Util/Model/Activity.php   | 18 ++++++++++++
 .../ActivityPub/Util/Model/ActivityFollow.php | 28 +++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/plugins/ActivityPub/Util/Model/Activity.php b/plugins/ActivityPub/Util/Model/Activity.php
index 10bfcf4e86..bae6636e00 100644
--- a/plugins/ActivityPub/Util/Model/Activity.php
+++ b/plugins/ActivityPub/Util/Model/Activity.php
@@ -32,6 +32,7 @@ declare(strict_types = 1);
 
 namespace Plugin\ActivityPub\Util\Model;
 
+use _PHPStan_4a258568e\Nette\NotImplementedException;
 use ActivityPhp\Type;
 use ActivityPhp\Type\AbstractObject;
 use App\Core\Event;
@@ -108,6 +109,23 @@ class Activity extends Model
                 break;
             case 'Follow':
                 ActivityFollow::handle_core_activity($actor, $type_activity, $type_object, $ap_act);
+                break;
+            case 'Undo':
+                $object_type = $type_object instanceof AbstractObject ? match ($type_object->get('type')) {
+                    'Note' => \App\Entity\Note::class,
+                    // no break
+                    default => throw new NotImplementedException('Unsupported Undo of Object Activity.'),
+                } : $type_object::class;
+                switch ($object_type) {
+                    case GSActivity::class:
+                        switch ($type_object->getVerb()) {
+                            case 'subscribe':
+                                ActivityFollow::handle_undo($actor, $type_activity, $type_object, $ap_act);
+                                break;
+                        }
+                        break;
+                }
+                break;
         }
         return $ap_act;
     }
diff --git a/plugins/ActivityPub/Util/Model/ActivityFollow.php b/plugins/ActivityPub/Util/Model/ActivityFollow.php
index ff1d2601a3..4e0a88b0fb 100644
--- a/plugins/ActivityPub/Util/Model/ActivityFollow.php
+++ b/plugins/ActivityPub/Util/Model/ActivityFollow.php
@@ -83,4 +83,32 @@ class ActivityFollow extends Activity
         DB::persist($ap_act);
         return $ap_act;
     }
+
+    public static function handle_undo(\App\Entity\Actor $actor, AbstractObject $type_activity, GSActivity $type_object, ?ActivitypubActivity &$ap_act): ActivitypubActivity
+    {
+        // Remove Subscription
+        DB::removeBy(Subscription::class, [
+            'subscriber_id' => $type_object->getActorId(),
+            'subscribed_id' => $type_object->getObjectId(),
+        ]);
+        // Store Activity
+        $act = GSActivity::create([
+            'actor_id'    => $actor->getId(),
+            'verb'        => 'undo',
+            'object_type' => 'activity',
+            'object_id'   => $type_object->getId(),
+            'created'     => new DateTime($type_activity->get('published') ?? 'now'),
+            'source'      => 'ActivityPub',
+        ]);
+        DB::persist($act);
+        // Store ActivityPub Activity
+        $ap_act = ActivitypubActivity::create([
+            'activity_id'  => $act->getId(),
+            'activity_uri' => $type_activity->get('id'),
+            'created'      => new DateTime($type_activity->get('published') ?? 'now'),
+            'modified'     => new DateTime(),
+        ]);
+        DB::persist($ap_act);
+        return $ap_act;
+    }
 }