2 files changed, 148 insertions, 0 deletions
diff --git a/lib/private/EventDispatcher/EventDispatcher.php b/lib/private/EventDispatcher/EventDispatcher.php
new file mode 100644
index 00000000000..474c902013b
--- /dev/null
+++ b/lib/private/EventDispatcher/EventDispatcher.php
@@ -0,0 +1,89 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OC\EventDispatcher;
+
+use OC\Broadcast\Events\BroadcastEvent;
+use OC\Log;
+use OCP\Broadcast\Events\IBroadcastEvent;
+use OCP\EventDispatcher\ABroadcastedEvent;
+use OCP\EventDispatcher\Event;
+use OCP\EventDispatcher\IEventDispatcher;
+use Psr\Container\ContainerInterface;
+use Psr\Log\LoggerInterface;
+use Symfony\Component\EventDispatcher\EventDispatcher as SymfonyDispatcher;
+use function get_class;
+
+class EventDispatcher implements IEventDispatcher {
+	public function __construct(
+		private SymfonyDispatcher $dispatcher,
+		private ContainerInterface $container,
+		private LoggerInterface $logger,
+	) {
+		// inject the event dispatcher into the logger
+		// this is done here because there is a cyclic dependency between the event dispatcher and logger
+		if ($this->logger instanceof Log || $this->logger instanceof Log\PsrLoggerAdapter) {
+			$this->logger->setEventDispatcher($this);
+		}
+	}
+
+	public function addListener(string $eventName,
+		callable $listener,
+		int $priority = 0): void {
+		$this->dispatcher->addListener($eventName, $listener, $priority);
+	}
+
+	public function removeListener(string $eventName,
+		callable $listener): void {
+		$this->dispatcher->removeListener($eventName, $listener);
+	}
+
+	public function addServiceListener(string $eventName,
+		string $className,
+		int $priority = 0): void {
+		$listener = new ServiceEventListener(
+			$this->container,
+			$className,
+			$this->logger
+		);
+
+		$this->addListener($eventName, $listener, $priority);
+	}
+
+	public function hasListeners(string $eventName): bool {
+		return $this->dispatcher->hasListeners($eventName);
+	}
+
+	/**
+	 * @deprecated
+	 */
+	public function dispatch(string $eventName,
+		Event $event): void {
+		$this->dispatcher->dispatch($event, $eventName);
+
+		if ($event instanceof ABroadcastedEvent && !$event->isPropagationStopped()) {
+			// Propagate broadcast
+			$this->dispatch(
+				IBroadcastEvent::class,
+				new BroadcastEvent($event)
+			);
+		}
+	}
+
+	public function dispatchTyped(Event $event): void {
+		$this->dispatch(get_class($event), $event);
+	}
+
+	/**
+	 * @return SymfonyDispatcher
+	 * @deprecated 20.0.0
+	 */
+	public function getSymfonyDispatcher(): SymfonyDispatcher {
+		return $this->dispatcher;
+	}
+}
diff --git a/lib/private/EventDispatcher/ServiceEventListener.php b/lib/private/EventDispatcher/ServiceEventListener.php
new file mode 100644
index 00000000000..f9cc85b4126
--- /dev/null
+++ b/lib/private/EventDispatcher/ServiceEventListener.php
@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OC\EventDispatcher;
+
+use OCP\AppFramework\QueryException;
+use OCP\EventDispatcher\Event;
+use OCP\EventDispatcher\IEventListener;
+use Psr\Container\ContainerInterface;
+use Psr\Log\LoggerInterface;
+use function sprintf;
+
+/**
+ * Lazy service event listener
+ *
+ * Makes it possible to lazy-route a dispatched event to a service instance
+ * created by the service container
+ */
+final class ServiceEventListener {
+	private ?IEventListener $service = null;
+
+	public function __construct(
+		private ContainerInterface $container,
+		private string $class,
+		private LoggerInterface $logger,
+	) {
+	}
+
+	public function __invoke(Event $event) {
+		if ($this->service === null) {
+			try {
+				// TODO: fetch from the app containers, otherwise any custom services,
+				//       parameters and aliases won't be resolved.
+				//       See https://github.com/nextcloud/server/issues/27793 for details.
+				$this->service = $this->container->get($this->class);
+			} catch (QueryException $e) {
+				$this->logger->error(
+					sprintf(
+						'Could not load event listener service %s: %s. Make sure the class is auto-loadable by the Nextcloud server container',
+						$this->class,
+						$e->getMessage()
+					),
+					[
+						'exception' => $e,
+					]
+				);
+				return;
+			}
+		}
+
+		$this->service->handle($event);
+	}
+}