feat: Introduce new UserEnumerationFilterEvent

This event allow apps to filter the user returned by queries.

Signed-off-by: Carl Schwan <carlschwan@kde.org>

Author: CarlSchwan

apps/user_status/lib/Controller/StatusesController.php

@@ -18,7 +18,9 @@
 use OCP\AppFramework\Http\DataResponse;
 use OCP\AppFramework\OCS\OCSNotFoundException;
 use OCP\AppFramework\OCSController;
+use OCP\EventDispatcher\IEventDispatcher;
 use OCP\IRequest;
+use OCP\User\Events\UserEnumerationFilterEvent;
 use OCP\UserStatus\IUserStatus;
 
 /**
@@ -37,7 +39,8 @@ class StatusesController extends OCSController {
 	public function __construct(
 		string $appName,
 		IRequest $request,
-		private StatusService $service,
+		private readonly StatusService $service,
+		private readonly IEventDispatcher $eventDispatcher,
 	) {
 		parent::__construct($appName, $request);
 	}
@@ -56,6 +59,15 @@ public function __construct(
 	public function findAll(?int $limit = null, ?int $offset = null): DataResponse {
 		$allStatuses = $this->service->findAll($limit, $offset);
 
+		$users = array_map(fn (UserStatus $userStatus): string => $userStatus->getUserId(), $allStatuses);
+		$event = new UserEnumerationFilterEvent($users);
+		$this->eventDispatcher->dispatchTyped($event);
+
+		if ($users !== $event->getUsers()) {
+			$removedUsers = $event->getFilteredOutUsers();
+			$allStatuses = array_filter($allStatuses, fn (UserStatus $userStatus): bool => in_array($userStatus->getUserId(), $removedUsers, true));
+		}
+
 		return new DataResponse(array_values(array_map(function ($userStatus) {
 			return $this->formatStatus($userStatus);
 		}, $allStatuses)));

apps/user_status/lib/Service/StatusService.php

@@ -81,7 +81,7 @@ public function __construct(
 	/**
 	 * @param int|null $limit
 	 * @param int|null $offset
-	 * @return UserStatus[]
+	 * @return list<UserStatus>
 	 */
 	public function findAll(?int $limit = null, ?int $offset = null): array {
 		// Return empty array if user enumeration is disabled or limited to groups
@@ -91,9 +91,9 @@ public function findAll(?int $limit = null, ?int $offset = null): array {
 			return [];
 		}
 
-		return array_map(function ($status) {
+		return array_values(array_map(function ($status) {
 			return $this->processStatus($status);
-		}, $this->mapper->findAll($limit, $offset));
+		}, $this->mapper->findAll($limit, $offset)));
 	}
 
 	/**

lib/composer/composer/autoload_classmap.php

@@ -988,6 +988,7 @@
     'OCP\\User\\Events\\UserChangedEvent' => $baseDir . '/lib/public/User/Events/UserChangedEvent.php',
     'OCP\\User\\Events\\UserCreatedEvent' => $baseDir . '/lib/public/User/Events/UserCreatedEvent.php',
     'OCP\\User\\Events\\UserDeletedEvent' => $baseDir . '/lib/public/User/Events/UserDeletedEvent.php',
+    'OCP\\User\\Events\\UserEnumerationFilterEvent' => $baseDir . '/lib/public/User/Events/UserEnumerationFilterEvent.php',
     'OCP\\User\\Events\\UserFirstTimeLoggedInEvent' => $baseDir . '/lib/public/User/Events/UserFirstTimeLoggedInEvent.php',
     'OCP\\User\\Events\\UserIdAssignedEvent' => $baseDir . '/lib/public/User/Events/UserIdAssignedEvent.php',
     'OCP\\User\\Events\\UserIdUnassignedEvent' => $baseDir . '/lib/public/User/Events/UserIdUnassignedEvent.php',

lib/composer/composer/autoload_static.php

@@ -1029,6 +1029,7 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OCP\\User\\Events\\UserChangedEvent' => __DIR__ . '/../../..' . '/lib/public/User/Events/UserChangedEvent.php',
         'OCP\\User\\Events\\UserCreatedEvent' => __DIR__ . '/../../..' . '/lib/public/User/Events/UserCreatedEvent.php',
         'OCP\\User\\Events\\UserDeletedEvent' => __DIR__ . '/../../..' . '/lib/public/User/Events/UserDeletedEvent.php',
+        'OCP\\User\\Events\\UserEnumerationFilterEvent' => __DIR__ . '/../../..' . '/lib/public/User/Events/UserEnumerationFilterEvent.php',
         'OCP\\User\\Events\\UserFirstTimeLoggedInEvent' => __DIR__ . '/../../..' . '/lib/public/User/Events/UserFirstTimeLoggedInEvent.php',
         'OCP\\User\\Events\\UserIdAssignedEvent' => __DIR__ . '/../../..' . '/lib/public/User/Events/UserIdAssignedEvent.php',
         'OCP\\User\\Events\\UserIdUnassignedEvent' => __DIR__ . '/../../..' . '/lib/public/User/Events/UserIdUnassignedEvent.php',

lib/public/User/Events/UserEnumerationFilterEvent.php

@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCP\User\Events;
+
+use OCP\AppFramework\Attribute\Consumable;
+use OCP\AppFramework\Attribute\Listenable;
+use OCP\EventDispatcher\Event;
+
+/**
+ * @brief This event is triggered when a list of users is returned to the user.
+ *
+ * Applications that restricts the enumeration of users should listen to this event
+ * and modify the list of users with the getUsers and setUsers method.
+ *
+ * @since 31.0.14
+ */
+#[Consumable(since: '31.0.14')]
+#[Listenable(since: '31.0.14')]
+class UserEnumerationFilterEvent extends Event {
+	/** @var list<string> $initialUsers */
+	private readonly array $initialUsers;
+
+	/**
+	 * @param list<string> $users
+	 * @since 31.0.14
+	 */
+	public function __construct(
+		private array $users,
+	) {
+		$this->initialUsers = $users;
+		parent::__construct();
+	}
+
+	/**
+	 * @return list<string>
+	 * @since 31.0.14
+	 */
+	public function getUsers(): array {
+		return $this->users;
+	}
+
+	/**
+	 * @param list<string> $users
+	 * @since 31.0.14
+	 */
+	public function setUsers(array $users): void {
+		$this->users = $users;
+	}
+
+	/**
+	 * Get the users what were filtered out by one of the listeners of this event.
+	 *
+	 * @return array<int<0, max>, string> $users
+	 * @since 31.0.14
+	 */
+	public function getFilteredOutUsers(): array {
+		return array_diff($this->initialUsers, $this->users);
+	}
+}