Merge pull request #9001 from annando/ap-forum

Improvements for delivering forum posts

include/api.php

@@ -5710,7 +5710,7 @@ function api_friendica_activity($type)
 
 	$id = $_REQUEST['id'] ?? 0;
 
-	$res = Item::performActivity($id, $verb);
+	$res = Item::performActivity($id, $verb, api_user());
 
 	if ($res) {
 		if ($type == "xml") {

include/conversation.php

@@ -712,8 +712,13 @@ function conversation_fetch_comments($thread_items, $pinned) {
 	$lineno = 0;
 	$actor = [];
 	$received = '';
+	$owner = '';
 
 	while ($row = Item::fetch($thread_items)) {
+		if (($row['verb'] == Activity::ANNOUNCE) && ($row['author-link'] == $owner)) {
+			continue;
+		}
+
 		if (($row['verb'] == Activity::ANNOUNCE) && !empty($row['contact-uid']) && ($row['received'] > $received) && ($row['thr-parent'] == $row['parent-uri'])) {
 			$actor = ['link' => $row['author-link'], 'avatar' => $row['author-avatar'], 'name' => $row['author-name']];
 			$received = $row['received'];
@@ -724,6 +729,10 @@ function conversation_fetch_comments($thread_items, $pinned) {
 			$parentlines[] = $lineno;
 		}
 
+		if (($row['gravity'] == GRAVITY_PARENT) && ($row['author-link'] != $row['owner-link'])) {
+			$owner = $row['owner-link'];
+		}
+
 		if ($row['gravity'] == GRAVITY_PARENT) {
 			$row['pinned'] = $pinned;
 		}
@@ -765,7 +774,7 @@ function conversation_add_children(array $parents, $block_authors, $order, $uid)
 		$max_comments = DI::config()->get('system', 'max_display_comments', 1000);
 	}
 
-	$params = ['order' => ['uid', 'commented' => true]];
+	$params = ['order' => ['gravity', 'uid', 'commented' => true]];
 
 	if ($max_comments > 0) {
 		$params['limit'] = $max_comments;

mod/subthread.php

@@ -34,7 +34,7 @@ function subthread_content(App $a)
 
 	$item_id = (($a->argc > 1) ? Strings::escapeTags(trim($a->argv[1])) : 0);
 
-	if (!Item::performActivity($item_id, 'follow')) {
+	if (!Item::performActivity($item_id, 'follow', local_user())) {
 		Logger::info('Following item failed', ['item' => $item_id]);
 		throw new HTTPException\BadRequestException();
 	}

src/Model/Item.php

@@ -1578,6 +1578,8 @@ class Item
 			return GRAVITY_COMMENT;
 		} elseif ($activity->match($item['verb'], Activity::FOLLOW)) {
 			return GRAVITY_ACTIVITY;
+		} elseif ($activity->match($item['verb'], Activity::ANNOUNCE)) {
+			return GRAVITY_ACTIVITY;
 		}
 		Logger::info('Unknown gravity for verb', ['verb' => $item['verb']]);
 		return GRAVITY_UNKNOWN;   // Should not happen
@@ -1798,6 +1800,7 @@ class Item
 		// It is mainly used in the "post_local" hook.
 		unset($item['api_source']);
 
+		self::transformToForumPost($item);
 
 		// Check for hashtags in the body and repair or add hashtag links
 		$item['body'] = self::setHashtags($item['body']);
@@ -1988,6 +1991,44 @@ class Item
 		return $current_post;
 	}
 
+	/**
+	 * Convert items to forum posts
+	 *
+	 * (public) forum posts in the new format consist of the regular post by the author
+	 * followed by an announce message sent from the forum account.
+	 * This means we have to look out for an announce message send by a forum account.
+	 *
+	 * @param array $item
+	 * @return void
+	 */
+	private static function transformToForumPost(array $item)
+	{
+		if ($item["verb"] != Activity::ANNOUNCE) {
+			// No announce message, so don't do anything
+			return;
+		}
+
+		$pcontact = Contact::selectFirst(['nurl'], ['id' => $item['author-id'], 'contact-type' => Contact::TYPE_COMMUNITY]);
+		if (empty($pcontact['nurl'])) {
+			// The announce message wasn't created by a forum account, so we don't need to continue
+			return;
+		}
+
+		$contact = Contact::selectFirst(['id'], ['nurl' => $pcontact['nurl'], 'uid' => $item['uid']]);
+		if (!empty($contact['id'])) {
+			$condition = ['uri-id' => $item['parent-uri-id'], 'uid' => $item['uid']];
+			Item::update(['owner-id' => $item['author-id'], 'contact-id' => $contact['id']], $condition);
+			$forum_item = Item::selectFirst(['id'], $condition);
+			if (!empty($forum_item['id'])) {
+				// This will trigger notifications like "X shared a new post"
+				UserItem::setNotification($forum_item['id']);
+
+				check_user_notification($forum_item['id']);
+			}
+			LOgger::info('Convert message into a forum message', ['uri-id' => $item['uri-id'], 'parent-uri-id' => $item['parent-uri-id'], 'uid' => $item['uid'], 'owner-id' => $item['author-id'], 'contact-id' => $contact['id']]);
+		}
+	}
+
 	/**
 	 * Distribute the given item to users who subscribed to their tags
 	 *
@@ -2673,6 +2714,10 @@ class Item
 
 		Worker::add(['priority' => PRIORITY_HIGH, 'dont_fork' => true], 'Notifier', Delivery::POST, $item_id);
 
+		/// @todo This code should be activated by the end of the year 2020
+		// See also "createActivityFromItem"
+		//Item::performActivity($item_id, 'announce', $uid);
+
 		return false;
 	}
 
@@ -3002,11 +3047,12 @@ class Item
 	 *
 	 * Toggle activities as like,dislike,attend of an item
 	 *
-	 * @param string $item_id
+	 * @param int $item_id
 	 * @param string $verb
 	 *            Activity verb. One of
 	 *            like, unlike, dislike, undislike, attendyes, unattendyes,
-	 *            attendno, unattendno, attendmaybe, unattendmaybe
+	 *            attendno, unattendno, attendmaybe, unattendmaybe,
+	 *            announce, unannouce
 	 * @return bool
 	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 	 * @throws \ImagickException
@@ -3014,15 +3060,15 @@ class Item
 	 *            array $arr
 	 *            'post_id' => ID of posted item
 	 */
-	public static function performActivity($item_id, $verb)
+	public static function performActivity(int $item_id, string $verb, int $uid)
 	{
-		if (!Session::isAuthenticated()) {
+		if (empty($uid)) {
 			return false;
 		}
 
-		Logger::log('like: verb ' . $verb . ' item ' . $item_id);
+		Logger::notice('Start create activity', ['verb' => $verb, 'item' => $item_id, 'user' => $uid]);
 
-		$item = self::selectFirst(self::ITEM_FIELDLIST, ['`id` = ? OR `uri` = ?', $item_id, $item_id]);
+		$item = self::selectFirst(self::ITEM_FIELDLIST, ['id' => $item_id]);
 		if (!DBA::isResult($item)) {
 			Logger::log('like: unknown item ' . $item_id);
 			return false;
@@ -3030,48 +3076,35 @@ class Item
 
 		$item_uri = $item['uri'];
 
-		$uid = $item['uid'];
+		if (!in_array($item['uid'], [0, $uid])) {
-		if (($uid == 0) && local_user()) {
-			$uid = local_user();
-		}
-
-		if (!Security::canWriteToUserWall($uid)) {
-			Logger::log('like: unable to write on wall ' . $uid);
 			return false;
 		}
 
 		if (!Item::exists(['uri-id' => $item['parent-uri-id'], 'uid' => $uid])) {
 			$stored = self::storeForUserByUriId($item['parent-uri-id'], $uid);
+			if (($item['parent-uri-id'] == $item['uri-id']) && !empty($stored)) {
+				$item = self::selectFirst(self::ITEM_FIELDLIST, ['id' => $stored]);
+				if (!DBA::isResult($item)) {
+					Logger::info('Could not fetch just created item - should not happen', ['stored' => $stored, 'uid' => $uid, 'item-uri' => $item_uri]);
+					return false;
+				}
+			}
 		}
 
 		// Retrieves the local post owner
-		$owner_self_contact = DBA::selectFirst('contact', [], ['uid' => $uid, 'self' => true]);
+		$owner = User::getOwnerDataById($uid);
-		if (!DBA::isResult($owner_self_contact)) {
+		if (empty($owner)) {
-			Logger::log('like: unknown owner ' . $uid);
+			Logger::info('Empty owner for user', ['uid' => $uid]);
 			return false;
 		}
 
 		// Retrieve the current logged in user's public contact
-		$author_id = public_contact();
+		$author_id = Contact::getIdForURL($owner['url']);
-
+		if (empty($author_id)) {
-		$author_contact = DBA::selectFirst('contact', ['url'], ['id' => $author_id]);
+			Logger::info('Empty public contact');
-		if (!DBA::isResult($author_contact)) {
-			Logger::log('like: unknown author ' . $author_id);
 			return false;
 		}
 
-		// Contact-id is the uid-dependant author contact
-		if (local_user() == $uid) {
-			$item_contact_id = $owner_self_contact['id'];
-		} else {
-			$item_contact_id = Contact::getIdForURL($author_contact['url'], $uid);
-			$item_contact = DBA::selectFirst('contact', [], ['id' => $item_contact_id]);
-			if (!DBA::isResult($item_contact)) {
-				Logger::log('like: unknown item contact ' . $item_contact_id);
-				return false;
-			}
-		}
-
 		$activity = null;
 		switch ($verb) {
 			case 'like':
@@ -3098,8 +3131,12 @@ class Item
 			case 'unfollow':
 				$activity = Activity::FOLLOW;
 				break;
+			case 'announce':
+			case 'unannounce':
+				$activity = Activity::ANNOUNCE;
+				break;
 			default:
-				Logger::log('like: unknown verb ' . $verb . ' for item ' . $item_id);
+				Logger::notice('unknown verb', ['verb' => $verb, 'item' => $item_id]);
 				return false;
 		}
 
@@ -3170,7 +3207,7 @@ class Item
 			'guid'          => System::createUUID(),
 			'uri'           => self::newURI($item['uid']),
 			'uid'           => $item['uid'],
-			'contact-id'    => $item_contact_id,
+			'contact-id'    => $owner['id'],
 			'wall'          => $item['wall'],
 			'origin'        => 1,
 			'network'       => Protocol::DFRN,

src/Module/Like.php

@@ -51,7 +51,7 @@ class Like extends BaseModule
 		// @TODO: Replace with parameter from router
 		$itemId = (($app->argc > 1) ? Strings::escapeTags(trim($app->argv[1])) : 0);
 
-		if (!Item::performActivity($itemId, $verb)) {
+		if (!Item::performActivity($itemId, $verb, local_user())) {
 			throw new HTTPException\BadRequestException();
 		}
 

src/Protocol/ActivityPub/Receiver.php

@@ -387,16 +387,11 @@ class Receiver
 
 			case 'as:Announce':
 				if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
-					$profile = APContact::getByURL($object_data['actor']);
+					$object_data['thread-completion'] = true;
-					// Reshared posts from persons appear as summary at the bottom
-					// If this isn't set, then a single reshare appears on top. This is used for groups.
-					$object_data['thread-completion'] = ($profile['type'] != 'Group');
 
 					$item = ActivityPub\Processor::createItem($object_data);
 					ActivityPub\Processor::postItem($object_data, $item);
 
-					// Add the bottom reshare information only for persons
-					if ($profile['type'] != 'Group') {
 					$announce_object_data = self::processObject($activity);
 					$announce_object_data['name'] = $type;
 					$announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
@@ -410,7 +405,6 @@ class Receiver
 
 					ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 				}
-				}
 				break;
 
 			case 'as:Like':

src/Protocol/ActivityPub/Transmitter.php

@@ -356,12 +356,14 @@ class Transmitter
 		}
 
 		$always_bcc = false;
+		$isforum = false;
 
 		// Check if we should always deliver our stuff via BCC
 		if (!empty($item['uid'])) {
-			$profile = Profile::getByUID($item['uid']);
+			$profile = User::getOwnerDataById($item['uid']);
 			if (!empty($profile)) {
 				$always_bcc = $profile['hide-friends'];
+				$isforum = $profile['account-type'] == User::ACCOUNT_TYPE_COMMUNITY;
 			}
 		}
 
@@ -369,7 +371,7 @@ class Transmitter
 			$always_bcc = true;
 		}
 
-		if (self::isAnnounce($item) || DI::config()->get('debug', 'total_ap_delivery')) {
+		if ((self::isAnnounce($item) && !$isforum) || DI::config()->get('debug', 'total_ap_delivery')) {
 			// Will be activated in a later step
 			$networks = Protocol::FEDERATED;
 		} else {
@@ -423,6 +425,10 @@ class Transmitter
 						continue;
 					}
 
+					if ($isforum && DBA::isResult($contact) && ($contact['dfrn'] == Protocol::DFRN)) {
+						continue;
+					}
+
 					if (!empty($profile = APContact::getByURL($contact['url'], false))) {
 						$data['to'][] = $profile['url'];
 					}
@@ -435,6 +441,10 @@ class Transmitter
 					continue;
 				}
 
+				if ($isforum && DBA::isResult($contact) && ($contact['dfrn'] == Protocol::DFRN)) {
+					continue;
+				}
+
 				if (!empty($profile = APContact::getByURL($contact['url'], false))) {
 					if ($contact['hidden'] || $always_bcc) {
 						$data['bcc'][] = $profile['url'];
@@ -454,7 +464,9 @@ class Transmitter
 						if ($item['gravity'] != GRAVITY_PARENT) {
 							// Comments to forums are directed to the forum
 							// But comments to forums aren't directed to the followers collection
-							if ($profile['type'] == 'Group') {
+							// This rule is only valid when the actor isn't the forum.
+							// The forum needs to transmit their content to their followers.
+							if (($profile['type'] == 'Group') && ($profile['url'] != $actor_profile['url'])) {
 								$data['to'][] = $profile['url'];
 							} else {
 								$data['cc'][] = $profile['url'];
@@ -555,6 +567,15 @@ class Transmitter
 	{
 		$inboxes = [];
 
+		$isforum = false;
+
+		if (!empty($item['uid'])) {
+			$profile = User::getOwnerDataById($item['uid']);
+			if (!empty($profile)) {
+				$isforum = $profile['account-type'] == User::ACCOUNT_TYPE_COMMUNITY;
+			}
+		}
+
 		if (DI::config()->get('debug', 'total_ap_delivery')) {
 			// Will be activated in a later step
 			$networks = Protocol::FEDERATED;
@@ -579,6 +600,10 @@ class Transmitter
 				continue;
 			}
 
+			if ($isforum && ($contact['dfrn'] == Protocol::DFRN)) {
+				continue;
+			}
+
 			if (Network::isUrlBlocked($contact['url'])) {
 				continue;
 			}
@@ -627,6 +652,8 @@ class Transmitter
 			$item_profile = APContact::getByURL($item['owner-link'], false);
 		}
 
+		$profile_uid = User::getIdForURL($item_profile['url']);
+
 		foreach (['to', 'cc', 'bto', 'bcc'] as $element) {
 			if (empty($permissions[$element])) {
 				continue;
@@ -639,7 +666,7 @@ class Transmitter
 					continue;
 				}
 
-				if ($item_profile && $receiver == $item_profile['followers']) {
+				if ($item_profile && ($receiver == $item_profile['followers']) && ($uid == $profile_uid)) {
 					$inboxes = array_merge($inboxes, self::fetchTargetInboxesforUser($uid, $personal));
 				} else {
 					if (Contact::isLocal($receiver)) {
@@ -807,6 +834,8 @@ class Transmitter
 			$type = 'Follow';
 		} elseif ($item['verb'] == Activity::TAG) {
 			$type = 'Add';
+		} elseif ($item['verb'] == Activity::ANNOUNCE) {
+			$type = 'Announce';
 		} else {
 			$type = '';
 		}
@@ -851,12 +880,13 @@ class Transmitter
 	 */
 	public static function createActivityFromItem($item_id, $object_mode = false)
 	{
+		Logger::info('Fetching activity', ['item' => $item_id]);
 		$item = Item::selectFirst([], ['id' => $item_id, 'parent-network' => Protocol::NATIVE_SUPPORT]);
-
 		if (!DBA::isResult($item)) {
 			return false;
 		}
 
+		/// @todo This code should be removed by the end of the year 2020
 		if ($item['wall'] && ($item['uri'] == $item['parent-uri'])) {
 			$owner = User::getOwnerDataById($item['uid']);
 			if (($owner['account-type'] == User::ACCOUNT_TYPE_COMMUNITY) && ($item['author-link'] != $owner['url'])) {
@@ -868,6 +898,21 @@ class Transmitter
 			}
 		}
 
+		/*
+		/// @todo This code should be activated by the end of the year 2020		
+		// See also "tagDeliver";
+		// In case of a forum post ensure to return the original post if author and forum are on the same machine
+		if (!empty($item['forum_mode'])) {
+			$author = Contact::getById($item['author-id'], ['nurl']);
+			if (!empty($author['nurl'])) {
+				$self = Contact::selectFirst(['uid'], ['nurl' => $author['nurl'], 'self' => true]);
+				if (!empty($self['uid'])) {
+					$item = Item::selectFirst([], ['uri-id' => $item['uri-id'], 'uid' => $self['uid']]);
+				}
+			}
+		}
+		*/
+
 		if (empty($type)) {
 			$condition = ['item-uri' => $item['uri'], 'protocol' => Conversation::PARCEL_ACTIVITYPUB];
 			$conversation = DBA::selectFirst('conversation', ['source'], $condition);
@@ -879,6 +924,7 @@ class Transmitter
 							unset($data['@context']);
 							unset($data['signature']);
 						}
+						Logger::info('Return stored conversation', ['item' => $item_id]);
 						return $data;
 					} elseif (in_array('as:' . $data['type'], Receiver::CONTENT_TYPES)) {
 						if (!empty($data['@context'])) {
@@ -909,7 +955,7 @@ class Transmitter
 		$data['id'] = $item['uri'] . '/' . $type;
 		$data['type'] = $type;
 
-		if (Item::isForumPost($item) && ($type != 'Announce')) {
+		if (($type != 'Announce') || ($item['gravity'] != GRAVITY_PARENT)) {
 			$data['actor'] = $item['author-link'];
 		} else {
 			$data['actor'] = $item['owner-link'];
@@ -926,7 +972,11 @@ class Transmitter
 		} elseif ($data['type'] == 'Add') {
 			$data = self::createAddTag($item, $data);
 		} elseif ($data['type'] == 'Announce') {
+			if ($item['verb'] == ACTIVITY::ANNOUNCE) {
+				$data['object'] = $item['thr-parent'];
+			} else {
 				$data = self::createAnnounce($item, $data);
+			}
 		} elseif ($data['type'] == 'Follow') {
 			$data['object'] = $item['parent-uri'];
 		} elseif ($data['type'] == 'Undo') {
@@ -947,7 +997,10 @@ class Transmitter
 
 		$owner = User::getOwnerDataById($uid);
 
-		if (!$object_mode && !empty($owner)) {
+		Logger::info('Fetched activity', ['item' => $item_id, 'uid' => $uid]);
+
+		// We don't sign if we aren't the actor. This is important for relaying content especially for forums
+		if (!$object_mode && !empty($owner) && ($data['actor'] == $owner['url'])) {
 			return LDSignature::sign($data, $owner);
 		} else {
 			return $data;
@@ -1009,6 +1062,9 @@ class Transmitter
 				$tags[] = ['type' => 'Hashtag', 'href' => $url, 'name' => '#' . $term['name']];
 			} else {
 				$contact = Contact::getByURL($term['url'], false, ['addr']);
+				if (empty($contact)) {
+					continue;
+				}
 				if (!empty($contact['addr'])) {
 					$mention = '@' . $contact['addr'];
 				} else {
@@ -1491,6 +1547,10 @@ class Transmitter
 	 */
 	public static function isAnnounce($item)
 	{
+		if ($item['verb'] == Activity::ANNOUNCE) {
+			return true;
+		}
+
 		$announce = self::getAnnounceArray($item);
 		if (empty($announce)) {
 			return false;

src/Protocol/DFRN.php

@@ -2162,6 +2162,7 @@ class DFRN
 				|| ($item["verb"] == Activity::ATTEND)
 				|| ($item["verb"] == Activity::ATTENDNO)
 				|| ($item["verb"] == Activity::ATTENDMAYBE)
+				|| ($item["verb"] == Activity::ANNOUNCE)
 			) {
 				$is_like = true;
 				$item["gravity"] = GRAVITY_ACTIVITY;

src/Worker/Notifier.php

@@ -36,7 +36,7 @@ use Friendica\Model\Post;
 use Friendica\Model\PushSubscriber;
 use Friendica\Model\Tag;
 use Friendica\Model\User;
-use Friendica\Network\Probe;
+use Friendica\Protocol\Activity;
 use Friendica\Protocol\ActivityPub;
 use Friendica\Protocol\Diaspora;
 use Friendica\Protocol\OStatus;
@@ -301,8 +301,10 @@ class Notifier
 
 				// if our parent is a public forum (forum_mode == 1), uplink to the origional author causing
 				// a delivery fork. private groups (forum_mode == 2) do not uplink
+				/// @todo Possibly we should not uplink when the author is the forum itself?
 
-				if ((intval($parent['forum_mode']) == 1) && !$top_level && ($cmd !== Delivery::UPLINK)) {
+				if ((intval($parent['forum_mode']) == 1) && !$top_level && ($cmd !== Delivery::UPLINK)
+					&& ($target_item['verb'] != Activity::ANNOUNCE)) {
 					Worker::add($a->queue['priority'], 'Notifier', Delivery::UPLINK, $target_id);
 				}
 
@@ -393,7 +395,7 @@ class Notifier
 			if ($followup) {
 				$recipients = $recipients_followup;
 			}
-			$condition = ['id' => $recipients, 'self' => false,
+			$condition = ['id' => $recipients, 'self' => false, 'uid' => [0, $uid],
 				'blocked' => false, 'pending' => false, 'archive' => false];
 			if (!empty($networks)) {
 				$condition['network'] = $networks;
@@ -439,7 +441,7 @@ class Notifier
 
 				// Add the relay to the list, avoid duplicates.
 				// Don't send community posts to the relay. Forum posts via the Diaspora protocol are looking ugly.
-				if (!$followup && !Item::isForumPost($target_item, $owner)) {
+				if (!$followup && !Item::isForumPost($target_item, $owner) && !self::isForumPost($target_item)) {
 					$relay_list = Diaspora::relayList($target_id, $relay_list);
 				}
 			}
@@ -473,7 +475,7 @@ class Notifier
 						continue;
 					}
 
-					if (self::skipDFRN($rr, $target_item, $parent, $thr_parent, $cmd)) {
+					if (self::skipDFRN($rr, $target_item, $parent, $thr_parent, $owner, $cmd)) {
 						Logger::info('Contact can be delivered via AP, so skip delivery via legacy DFRN/Diaspora', ['id' => $target_id, 'url' => $rr['url']]);
 						continue;
 					}
@@ -528,7 +530,7 @@ class Notifier
 				continue;
 			}
 
-			if (self::skipDFRN($contact, $target_item, $parent, $thr_parent, $cmd)) {
+			if (self::skipDFRN($contact, $target_item, $parent, $thr_parent, $owner, $cmd)) {
 				Logger::info('Contact can be delivered via AP, so skip delivery via legacy DFRN/Diaspora', ['target' => $target_id, 'url' => $contact['url']]);
 				continue;
 			}
@@ -646,12 +648,13 @@ class Notifier
 	 * @param array  $item       The post
 	 * @param array  $parent     The parent
 	 * @param array  $thr_parent The thread parent
+	 * @param array  $owner      Owner array
 	 * @param string $cmd        Notifier command
 	 * @return bool
 	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 	 * @throws \ImagickException
 	 */
-	private static function skipDFRN($contact, $item, $parent, $thr_parent, $cmd)
+	private static function skipDFRN($contact, $item, $parent, $thr_parent, $owner, $cmd)
 	{
 		if (empty($parent['network'])) {
 			return false;
@@ -682,6 +685,12 @@ class Notifier
 			return false;
 		}
 
+		// For the time being we always deliver forum post via DFRN if possible
+		// This can be removed possible at the end of 2020 when hopefully most system can process AP forum posts
+		if ($owner['account-type'] == User::ACCOUNT_TYPE_COMMUNITY) {
+			return false;
+		}
+
 		// We deliver reshares via AP whenever possible
 		if (ActivityPub\Transmitter::isAnnounce($item)) {
 			return true;
@@ -812,4 +821,15 @@ class Notifier
 
 		return $delivery_queue_count;
 	}
+
+	/**
+	 * Check if the delivered item is a forum post
+	 *
+	 * @param array $item
+	 * @return boolean
+	 */
+	public static function isForumPost(array $item)
+	{
+		return !empty($item['forum_mode']);
+	}
 }