Implement UndoHandler; register all activity handlers

src/ActivityEventHandlers/UndoHandler.php

@@ -0,0 +1,156 @@
+<?php
+
+namespace ActivityPub\ActivityEventHandlers;
+
+use ActivityPub\Entities\ActivityPubObject;
+use ActivityPub\Objects\CollectionsService;
+use ActivityPub\Objects\ObjectsService;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+class UndoHandler implements EventSubscriberInterface
+{
+    /**
+     * @var ObjectsService
+     */
+    private $objectsService;
+
+    /**
+     * @var CollectionsService
+     */
+    private $collectionsService;
+
+    public static function getSubscribedEvents()
+    {
+        return array(
+            InboxActivityEvent::NAME => 'handleInbox',
+            OutboxActivityEvent::NAME => 'handleOutbox',
+        );
+    }
+
+    public function __construct( ObjectsService $objectsService,
+                                 CollectionsService $collectionsService )
+    {
+        $this->objectsService = $objectsService;
+        $this->collectionsService = $collectionsService;
+    }
+
+    // make sure actors match for undo activity and its object
+    // Undoing likes: remove from likes/liked collection
+    // Undoing follow: remove from following/followers collection
+
+    public function handleInbox( InboxActivityEvent $event )
+    {
+        $activity = $event->getActivity();
+        if ( $activity['type'] !== 'Undo' ) {
+            return;
+        }
+        $object = $this->getUndoObject( $activity );
+        if ( ! ( $object && $object->hasField( 'type' ) ) ) {
+            return;
+        }
+        if ( ! $this->undoIsValid( $activity, $object ) ) {
+            return;
+        }
+        switch ( $object['type'] ) {
+            case 'Follow':
+                $this->removeFromCollection( $object['object'], 'followers', $object['actor'] );
+                break;
+            case 'Like':
+                $this->removeFromCollection( $object['object'], 'likes', $object['actor'] );
+                break;
+            default:
+                return;
+        }
+    }
+
+    public function handleOutbox( OutboxActivityEvent $event )
+    {
+        $activity = $event->getActivity();
+        if ( $activity['type'] !== 'Undo' ) {
+            return;
+        }
+        $object = $this->getUndoObject( $activity );
+        if ( ! ( $object && $object->hasField( 'type' ) ) ) {
+            return;
+        }
+        if ( ! $this->undoIsValid( $activity, $object ) ) {
+            return;
+        }
+        switch ( $object['type'] ) {
+            case 'Follow':
+                $this->removeFromCollection( $object['actor'], 'following', $object['object'] );
+                break;
+            case 'Like':
+                $this->removeFromCollection( $object['actor'], 'liked', $object['object'] );
+                break;
+            default:
+                return;
+        }
+    }
+
+    private function undoIsValid( $activity, ActivityPubObject $undoObject )
+    {
+        if ( ! array_key_exists( 'actor', $activity ) ) {
+            return false;
+        }
+        $actorId = $activity['actor'];
+        if ( is_array( $actorId ) && array_key_exists( 'id', $actorId ) ) {
+            $actorId = $actorId['id'];
+        }
+        if ( ! is_string( $actorId ) ) {
+            return false;
+        }
+        $objectActor = $undoObject['actor'];
+        if ( ! $objectActor ) {
+            return false;
+        }
+        return $actorId == $objectActor['id'];
+    }
+
+    private function removeFromCollection( $object, $collectionField, $itemId )
+    {
+        if ( ! ( $object && $object instanceof ActivityPubObject ) ) {
+            return;
+        }
+        if ( ! $object->hasField( $collectionField ) ) {
+            return;
+        }
+        $collection = $object[$collectionField];
+        if ( ! ( $collection && $collection instanceof ActivityPubObject ) ) {
+            return;
+        }
+        if ( ! $itemId ) {
+            return;
+        }
+        if ( $itemId instanceof ActivityPubObject && $itemId->hasField( 'id' ) ) {
+            $itemId = $itemId['id'];
+        } else if ( is_array( $itemId ) && array_key_exists( 'id', $itemId ) ) {
+            $itemId = $itemId['id'];
+        }
+        if ( ! is_string( $itemId ) ) {
+            return;
+        }
+        $this->collectionsService->removeItem( $collection, $itemId );
+    }
+
+    /**
+     * Gets the object of the undo activity as an ActivityPubObject
+     * @param $activity
+     * @return \ActivityPub\Entities\ActivityPubObject|null
+     */
+    private function getUndoObject( $activity )
+    {
+        $objectId = $activity['object'];
+        if ( is_array( $objectId ) ) {
+            if ( ! array_key_exists( 'id', $objectId ) ) {
+                return null;
+            }
+            $objectId = $objectId['id'];
+        }
+        $object = $this->objectsService->dereference( $objectId );
+        if ( ! $object ) {
+            return null;
+        }
+        return $object;
+    }
+}

src/ActivityPub.php

@@ -6,10 +6,14 @@ namespace ActivityPub;
 
 use ActivityPub\ActivityEventHandlers\AcceptHandler;
 use ActivityPub\ActivityEventHandlers\AddHandler;
+use ActivityPub\ActivityEventHandlers\AnnounceHandler;
 use ActivityPub\ActivityEventHandlers\CreateHandler;
 use ActivityPub\ActivityEventHandlers\DeleteHandler;
 use ActivityPub\ActivityEventHandlers\FollowHandler;
+use ActivityPub\ActivityEventHandlers\LikeHandler;
 use ActivityPub\ActivityEventHandlers\NonActivityHandler;
+use ActivityPub\ActivityEventHandlers\RemoveHandler;
+use ActivityPub\ActivityEventHandlers\UndoHandler;
 use ActivityPub\ActivityEventHandlers\UpdateHandler;
 use ActivityPub\ActivityEventHandlers\ValidationHandler;
 use ActivityPub\Auth\AuthListener;
@@ -92,6 +96,10 @@ class ActivityPub
         $dispatcher->addSubscriber( $this->module->get( FollowHandler::class ) );
         $dispatcher->addSubscriber( $this->module->get( AcceptHandler::class ) );
         $dispatcher->addSubscriber( $this->module->get( AddHandler::class ) );
+        $dispatcher->addSubscriber( $this->module->get( RemoveHandler::class ) );
+        $dispatcher->addSubscriber( $this->module->get( LikeHandler::class ) );
+        $dispatcher->addSubscriber( $this->module->get( AnnounceHandler::class ) );
+        $dispatcher->addSubscriber( $this->module->get( UndoHandler::class ) );
     }
 
     /**

src/Config/ActivityPubModule.php

@@ -6,10 +6,14 @@ namespace ActivityPub\Config;
 
 use ActivityPub\ActivityEventHandlers\AcceptHandler;
 use ActivityPub\ActivityEventHandlers\AddHandler;
+use ActivityPub\ActivityEventHandlers\AnnounceHandler;
 use ActivityPub\ActivityEventHandlers\CreateHandler;
 use ActivityPub\ActivityEventHandlers\DeleteHandler;
 use ActivityPub\ActivityEventHandlers\FollowHandler;
+use ActivityPub\ActivityEventHandlers\LikeHandler;
 use ActivityPub\ActivityEventHandlers\NonActivityHandler;
+use ActivityPub\ActivityEventHandlers\RemoveHandler;
+use ActivityPub\ActivityEventHandlers\UndoHandler;
 use ActivityPub\ActivityEventHandlers\UpdateHandler;
 use ActivityPub\ActivityEventHandlers\ValidationHandler;
 use ActivityPub\Auth\AuthListener;
@@ -154,6 +158,24 @@ class ActivityPubModule
         $this->injector->register( AddHandler::class, AddHandler::class )
             ->addArgument( new Reference( ObjectsService::class ) )
             ->addArgument( new Reference( CollectionsService::class ) );
+
+        $this->injector->register( RemoveHandler::class, RemoveHandler::class )
+            ->addArgument( new Reference( ObjectsService::class ) )
+            ->addArgument( new Reference( CollectionsService::class ) );
+
+        $this->injector->register( LikeHandler::class, LikeHandler::class )
+            ->addArgument( new Reference( ObjectsService::class ) )
+            ->addArgument( new Reference( CollectionsService::class ) )
+            ->addArgument( new Reference( ContextProvider::class ) );
+
+        $this->injector->register( AnnounceHandler::class, AnnounceHandler::class )
+            ->addArgument( new Reference( ObjectsService::class ) )
+            ->addArgument( new Reference( CollectionsService::class ) )
+            ->addArgument( new Reference( ContextProvider::class ) );
+
+        $this->injector->register( UndoHandler::class, UndoHandler::class )
+            ->addArgument( new Reference( ObjectsService::class ) )
+            ->addArgument( new Reference( CollectionsService::class ) );
     }
 
     /**