Apply fixes from StyleCI

framework/core/src/Notification/Driver/GroupableNotificationDriverInterface.php

@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Notification\Driver;
+
+interface GroupableNotificationDriverInterface extends NotificationDriverInterface
+{
+    /**
+     * Implies the delay to wait before sending out notifications to allow blueprintGrouping to happen.
+     *
+     * @todo Enable for v2.0+
+     */
+    public function blueprintGroupingDelay(): ?\DateInterval;
+
+    public function sendGrouped();
+}

framework/core/src/Notification/Job/DelayedBlueprintGroupingJob.php

@@ -0,0 +1,41 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Notification\Job;
+
+use Flarum\Notification\Blueprint\BlueprintInterface;
+use Flarum\Notification\Driver\NotificationDriverInterface;
+use Flarum\Queue\AbstractJob;
+use Flarum\User\User;
+use Illuminate\Queue\Middleware\WithoutOverlapping;
+
+class DelayedBlueprintGroupingJob extends AbstractJob
+{
+    private BlueprintInterface $blueprint;
+    private NotificationDriverInterface $driver;
+    private User $user;
+
+    public function __construct(BlueprintInterface $blueprint, User $user, NotificationDriverInterface $driver)
+    {
+        $this->blueprint = $blueprint;
+        $this->driver = $driver;
+        $this->user = $user;
+    }
+
+    public function handle()
+    {
+    }
+
+    public function middleware()
+    {
+        return [
+            (new WithoutOverlapping('delayed-blueprint-grouping:'.$this->user->id))->dontRelease()
+        ];
+    }
+}

framework/core/src/Notification/NotificationSyncer.php

@@ -10,8 +10,11 @@
 namespace Flarum\Notification;
 
 use Flarum\Notification\Blueprint\BlueprintInterface;
+use Flarum\Notification\Driver\GroupableNotificationDriverInterface;
 use Flarum\Notification\Driver\NotificationDriverInterface;
+use Flarum\Notification\Job\DelayedBlueprintGroupingJob;
 use Flarum\User\User;
+use Illuminate\Contracts\Queue\Queue;
 
 /**
  * The Notification Syncer commits notification blueprints to the database, and
@@ -47,6 +50,13 @@ class NotificationSyncer
      */
     protected static $beforeSendingCallbacks = [];
 
+    private Queue $queue;
+
+    public function __construct(Queue $queue)
+    {
+        $this->queue = $queue;
+    }
+
     /**
      * Sync a notification so that it is visible to the specified users, and not
      * visible to anyone else. If it is being made visible for the first time,
@@ -107,7 +117,21 @@ class NotificationSyncer
         // didn't have a record in the database). As both operations can be
         // intensive on resources (database and mail server), we queue them.
         foreach (static::getNotificationDrivers() as $driverName => $driver) {
-            $driver->send($blueprint, $newRecipients);
+            if ($driver instanceof GroupableNotificationDriverInterface) {
+                $delay = $driver->blueprintGroupingDelay();
+
+                foreach ($newRecipients as $recipient) {
+                    $job = new DelayedBlueprintGroupingJob(
+                        $blueprint,
+                        $recipient,
+                        $driver
+                    );
+
+                    $this->queue->later($delay, $job);
+                }
+            } else {
+                $driver->send($blueprint, $newRecipients);
+            }
         }
     }