Move command classes to domain namespaces

They will probably be refactored away at a later stage (when we get
rid of the command bus). Until then, this lets us remove the
Flarum\Core namespace and actually feels quite clean.

src/User/Command/DeleteAvatarHandler.php

@@ -0,0 +1,80 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\User\Command;
+
+use Flarum\Event\AvatarWillBeDeleted;
+use Flarum\Foundation\DispatchEventsTrait;
+use Flarum\User\AssertPermissionTrait;
+use Flarum\User\UserRepository;
+use Illuminate\Contracts\Events\Dispatcher;
+use League\Flysystem\FilesystemInterface;
+
+class DeleteAvatarHandler
+{
+    use DispatchEventsTrait;
+    use AssertPermissionTrait;
+
+    /**
+     * @var UserRepository
+     */
+    protected $users;
+
+    /**
+     * @var FilesystemInterface
+     */
+    protected $uploadDir;
+
+    /**
+     * @param Dispatcher $events
+     * @param UserRepository $users
+     * @param FilesystemInterface $uploadDir
+     */
+    public function __construct(Dispatcher $events, UserRepository $users, FilesystemInterface $uploadDir)
+    {
+        $this->events = $events;
+        $this->users = $users;
+        $this->uploadDir = $uploadDir;
+    }
+
+    /**
+     * @param DeleteAvatar $command
+     * @return \Flarum\User\User
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     */
+    public function handle(DeleteAvatar $command)
+    {
+        $actor = $command->actor;
+
+        $user = $this->users->findOrFail($command->userId);
+
+        if ($actor->id !== $user->id) {
+            $this->assertCan($actor, 'edit', $user);
+        }
+
+        $avatarPath = $user->avatar_path;
+        $user->changeAvatarPath(null);
+
+        $this->events->fire(
+            new AvatarWillBeDeleted($user, $actor)
+        );
+
+        $user->save();
+
+        if ($this->uploadDir->has($avatarPath)) {
+            $this->uploadDir->delete($avatarPath);
+        }
+
+        $this->dispatchEventsFor($user, $actor);
+
+        return $user;
+    }
+}