Allow apps to register SystemTags plugins

apps/dav/lib/RootCollection.php

@@ -71,7 +71,8 @@ class RootCollection extends SimpleCollection {
 			\OC::$server->getSystemTagManager(),
 			\OC::$server->getSystemTagObjectMapper(),
 			\OC::$server->getUserSession(),
-			\OC::$server->getGroupManager()
+			\OC::$server->getGroupManager(),
+			\OC::$server->getEventDispatcher()
 		);
 		$commentsCollection = new Comments\RootCollection(
 			\OC::$server->getCommentsManager(),

apps/dav/lib/SystemTag/SystemTagsRelationsCollection.php

@@ -25,10 +25,12 @@ namespace OCA\DAV\SystemTag;
 
 use OCP\SystemTag\ISystemTagManager;
 use OCP\SystemTag\ISystemTagObjectMapper;
+use OCP\SystemTag\SystemTagsEntityEvent;
 use Sabre\DAV\Exception\Forbidden;
 use Sabre\DAV\SimpleCollection;
 use OCP\IUserSession;
 use OCP\IGroupManager;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 
 class SystemTagsRelationsCollection extends SimpleCollection {
 
@@ -39,12 +41,14 @@ class SystemTagsRelationsCollection extends SimpleCollection {
 	 * @param ISystemTagObjectMapper $tagMapper
 	 * @param IUserSession $userSession
 	 * @param IGroupManager $groupManager
+	 * @param EventDispatcherInterface $dispatcher
 	 */
 	public function __construct(
 		ISystemTagManager $tagManager,
 		ISystemTagObjectMapper $tagMapper,
 		IUserSession $userSession,
-		IGroupManager $groupManager
+		IGroupManager $groupManager,
+		EventDispatcherInterface $dispatcher
 	) {
 		$children = [
 			new SystemTagsObjectTypeCollection(
@@ -60,6 +64,20 @@ class SystemTagsRelationsCollection extends SimpleCollection {
 			),
 		];
 
+		$event = new SystemTagsEntityEvent(SystemTagsEntityEvent::EVENT_ENTITY);
+		$dispatcher->dispatch(SystemTagsEntityEvent::EVENT_ENTITY, $event);
+
+		foreach ($event->getEntityCollections() as $entity => $entityExistsFunction) {
+			$children[] = new SystemTagsObjectTypeCollection(
+				$entity,
+				$tagManager,
+				$tagMapper,
+				$userSession,
+				$groupManager,
+				$entityExistsFunction
+			);
+		}
+
 		parent::__construct('root', $children);
 	}
 

lib/public/SystemTag/SystemTagsEntityEvent.php

@@ -0,0 +1,76 @@
+<?php
+/**
+ * @author Joas Schilling <nickvergessen@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCP\SystemTag;
+
+use Symfony\Component\EventDispatcher\Event;
+
+/**
+ * Class SystemTagsEntityEvent
+ *
+ * @package OCP\SystemTag
+ * @since 9.2.0
+ */
+class SystemTagsEntityEvent extends Event {
+
+	const EVENT_ENTITY = 'OCP\SystemTag\ISystemTagManager::registerEntity';
+
+	/** @var string */
+	protected $event;
+	/** @var \Closure[] */
+	protected $collections;
+
+	/**
+	 * SystemTagsEntityEvent constructor.
+	 *
+	 * @param string $event
+	 * @since 9.2.0
+	 */
+	public function __construct($event) {
+		$this->event = $event;
+		$this->collections = [];
+	}
+
+	/**
+	 * @param string $name
+	 * @param \Closure $entityExistsFunction The closure should take one
+	 *                 argument, which is the id of the entity, that tags
+	 *                 should be handled for. The return should then be bool,
+	 *                 depending on whether tags are allowed (true) or not.
+	 * @throws \OutOfBoundsException when the entity name is already taken
+	 * @since 9.2.0
+	 */
+	public function addEntityCollection($name, \Closure $entityExistsFunction) {
+		if (isset($this->collections[$name])) {
+			throw new \OutOfBoundsException('Duplicate entity name "' . $name . '"');
+		}
+
+		$this->collections[$name] = $entityExistsFunction;
+	}
+
+	/**
+	 * @return \Closure[]
+	 * @since 9.2.0
+	 */
+	public function getEntityCollections() {
+		return $this->collections;
+	}
+}