Rework notifications architecture

- The recipient(s) are the concern of the notifier/sender, not the
notification itself
- Allow “retraction” of notifications (e.g. if a discussion is
stickied, but then it is unstickied)
- Misc. cleanup

src/Core/Handlers/Events/DiscussionRenamedNotifier.php

@@ -27,10 +27,16 @@ class DiscussionRenamedNotifier
     {
         $post = $this->createPost($event);
 
-        $event->discussion->addPost($post);
+        $post = $event->discussion->addPost($post);
 
         if ($event->discussion->start_user_id !== $event->user->id) {
-            $this->sendNotification($event, $post);
+            $notification = new DiscussionRenamedNotification($event->discussion, $post->user, $post);
+
+            if ($post->exists) {
+                $this->notifier->send($notification, [$post->discussion->startUser]);
+            } else {
+                $this->notifier->retract($notification);
+            }
         }
     }
 
@@ -43,16 +49,4 @@ class DiscussionRenamedNotifier
             $event->discussion->title
         );
     }
-
-    protected function sendNotification(DiscussionWasRenamed $event, DiscussionRenamedPost $post)
-    {
-        $notification = new DiscussionRenamedNotification(
-            $event->discussion->startUser,
-            $event->user,
-            $post,
-            $event->oldTitle
-        );
-
-        $this->notifier->send($notification);
-    }
 }

src/Core/Models/Notification.php

@@ -60,7 +60,7 @@ class Notification extends Model
      */
     public function setDataAttribute($value)
     {
-        $this->attributes['data'] = json_encode($value);
+        $this->attributes['data'] = $value ? json_encode($value) : null;
     }
 
     /**

src/Core/Notifications/Notifier.php

@@ -1,6 +1,7 @@
 <?php namespace Flarum\Core\Notifications;
 
 use Flarum\Core\Notifications\Types\Notification;
+use Flarum\Core\Notifications\Senders\RetractableSender;
 use Flarum\Core\Models\Notification as NotificationModel;
 use Flarum\Core\Models\User;
 use Illuminate\Container\Container;
@@ -18,12 +19,28 @@ class Notifier
         $this->container = $container;
     }
 
-    public function send(Notification $notification)
+    public function send(Notification $notification, array $users)
     {
         foreach ($this->methods as $method => $sender) {
             $sender = $this->container->make($sender);
-            if ($notification->getRecipient()->shouldNotify($notification::getType(), $method) && $sender::compatibleWith($notification)) {
-                $sender->send($notification);
+
+            if ($sender::compatibleWith($notification)) {
+                foreach ($users as $user) {
+                    if ($user->shouldNotify($notification::getType(), $method)) {
+                        $sender->send($notification, $user);
+                    }
+                }
+            }
+        }
+    }
+
+    public function retract(Notification $notification)
+    {
+        foreach ($this->methods as $method => $sender) {
+            $sender = $this->container->make($sender);
+
+            if ($sender instanceof RetractableSender && $sender::compatibleWith($notification)) {
+                $sender->retract($notification);
             }
         }
     }

src/Core/Notifications/Senders/NotificationAlerter.php

@@ -2,22 +2,31 @@
 
 use Flarum\Core\Notifications\Types\Notification;
 use Flarum\Core\Models\Notification as NotificationModel;
+use Flarum\Core\Models\User;
 use ReflectionClass;
 
-class NotificationAlerter implements NotificationSender
+class NotificationAlerter implements NotificationSender, RetractableSender
 {
-    public function send(Notification $notification)
+    public function send(Notification $notification, User $user)
     {
         $model = NotificationModel::alert(
-            $notification->getRecipient()->id,
+            $user->id,
             $notification::getType(),
             $notification->getSender()->id,
             $notification->getSubject()->id,
             $notification->getAlertData()
         );
+
         $model->save();
     }
 
+    public function retract(Notification $notification)
+    {
+        $models = NotificationModel::where('type', $notification::getType())
+            ->where('subject_id', $notification->getSubject()->id)
+            ->delete();
+    }
+
     public static function compatibleWith($className)
     {
         return (new ReflectionClass($className))->implementsInterface('Flarum\Core\Notifications\Types\AlertableNotification');

src/Core/Notifications/Senders/NotificationEmailer.php

@@ -1,6 +1,7 @@
 <?php namespace Flarum\Core\Notifications\Senders;
 
 use Flarum\Core\Notifications\Types\Notification;
+use Flarum\Core\Models\User;
 use Flarum\Core\Models\Forum;
 use Illuminate\Mail\Mailer;
 use ReflectionClass;
@@ -13,10 +14,9 @@ class NotificationEmailer implements NotificationSender
         $this->forum = $forum;
     }
 
-    public function send(Notification $notification)
+    public function send(Notification $notification, User $user)
     {
-        $this->mailer->send($notification->getEmailView(), ['notification' => $notification], function ($message) use ($notification) {
-            $recipient = $notification->getRecipient();
+        $this->mailer->send($notification->getEmailView(), ['notification' => $notification], function ($message) use ($notification, $recipient) {
             $message->to($recipient->email, $recipient->username)
                     ->subject('['.$this->forum->title.'] '.$notification->getEmailSubject());
         });

src/Core/Notifications/Senders/NotificationSender.php

@@ -1,10 +1,11 @@
 <?php namespace Flarum\Core\Notifications\Senders;
 
 use Flarum\Core\Notifications\Types\Notification;
+use Flarum\Core\Models\User;
 
 interface NotificationSender
 {
-    public function send(Notification $notification);
+    public function send(Notification $notification, User $user);
 
     public static function compatibleWith($class);
 }

src/Core/Notifications/Senders/RetractableSender.php

@@ -0,0 +1,8 @@
+<?php namespace Flarum\Core\Notifications\Senders;
+
+use Flarum\Core\Notifications\Types\Notification;
+
+interface RetractableSender
+{
+    public function retract(Notification $notification);
+}

src/Core/Notifications/Types/AlertableNotification.php

@@ -1,8 +0,0 @@
-<?php namespace Flarum\Core\Notifications\Types;
-
-interface AlertableNotification
-{
-    public function getAlertData();
-
-    public static function getType();
-}

src/Core/Notifications/Types/DiscussionRenamedNotification.php

@@ -1,33 +1,37 @@
 <?php namespace Flarum\Core\Notifications\Types;
 
 use Flarum\Core\Models\User;
+use Flarum\Core\Models\Discussion;
 use Flarum\Core\Models\DiscussionRenamedPost;
 
 class DiscussionRenamedNotification extends Notification implements AlertableNotification
 {
-    public $post;
+    protected $discussion;
 
-    public $oldTitle;
+    protected $sender;
 
-    public function __construct(User $recipient, User $sender, DiscussionRenamedPost $post, $oldTitle)
+    protected $post;
+
+    public function __construct(Discussion $discussion, User $sender, DiscussionRenamedPost $post = null)
     {
+        $this->discussion = $discussion;
+        $this->sender = $sender;
         $this->post = $post;
-        $this->oldTitle = $oldTitle;
-
-        parent::__construct($recipient, $sender);
     }
 
     public function getSubject()
     {
-        return $this->post->discussion;
+        return $this->discussion;
+    }
+
+    public function getSender()
+    {
+        return $this->sender;
     }
 
     public function getAlertData()
     {
-        return [
-            'number'   => $this->post->number,
-            'oldTitle' => $this->oldTitle
-        ];
+        return ['postNumber' => $this->post->number];
     }
 
     public static function getType()

src/Core/Notifications/Types/Notification.php

@@ -1,36 +1,6 @@
 <?php namespace Flarum\Core\Notifications\Types;
 
-use Flarum\Core\Models\User;
-
 abstract class Notification
 {
-    protected $recipient;
-
-    protected $sender;
-
-    public function __construct(User $recipient, User $sender)
-    {
-        $this->recipient = $recipient;
-        $this->sender = $sender;
-    }
-
-    public function getRecipient()
-    {
-        return $this->recipient;
-    }
-
-    public function getSender()
-    {
-        return $this->sender;
-    }
-
-    public static function getType()
-    {
-        return null;
-    }
-
-    public static function getSubjectModel()
-    {
-        return null;
-    }
+    abstract public static function getType();
 }

src/Core/Repositories/EloquentNotificationRepository.php

@@ -5,15 +5,15 @@ use DB;
 
 class EloquentNotificationRepository implements NotificationRepositoryInterface
 {
-    public function findByUser($userId, $count = null, $start = 0)
+    public function findByUser($userId, $limit = null, $offset = 0)
     {
         $primaries = Notification::select(DB::raw('MAX(id) AS id'), DB::raw('SUM(is_read = 0) AS unread_count'))
             ->where('user_id', $userId)
             ->whereIn('type', array_keys(Notification::getTypes()))
             ->groupBy('type', 'subject_id')
             ->orderBy('time', 'desc')
-            ->skip($start)
-            ->take($count);
+            ->skip($offset)
+            ->take($limit);
 
         return Notification::with('subject')
             ->select('notifications.*', 'p.unread_count')