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/Post/Command/PostReplyHandler.php

@@ -0,0 +1,112 @@
+<?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\Post\Command;
+
+use DateTime;
+use Flarum\Discussion\DiscussionRepository;
+use Flarum\Foundation\DispatchEventsTrait;
+use Flarum\Notification\NotificationSyncer;
+use Flarum\Post\CommentPost;
+use Flarum\Post\Event\Saving;
+use Flarum\Post\PostValidator;
+use Flarum\User\AssertPermissionTrait;
+use Illuminate\Contracts\Events\Dispatcher;
+
+class PostReplyHandler
+{
+    use DispatchEventsTrait;
+    use AssertPermissionTrait;
+
+    /**
+     * @var DiscussionRepository
+     */
+    protected $discussions;
+
+    /**
+     * @var \Flarum\Notification\NotificationSyncer
+     */
+    protected $notifications;
+
+    /**
+     * @var \Flarum\Post\PostValidator
+     */
+    protected $validator;
+
+    /**
+     * @param Dispatcher $events
+     * @param DiscussionRepository $discussions
+     * @param \Flarum\Notification\NotificationSyncer $notifications
+     * @param PostValidator $validator
+     */
+    public function __construct(
+        Dispatcher $events,
+        DiscussionRepository $discussions,
+        NotificationSyncer $notifications,
+        PostValidator $validator
+    ) {
+        $this->events = $events;
+        $this->discussions = $discussions;
+        $this->notifications = $notifications;
+        $this->validator = $validator;
+    }
+
+    /**
+     * @param PostReply $command
+     * @return CommentPost
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     */
+    public function handle(PostReply $command)
+    {
+        $actor = $command->actor;
+
+        // Make sure the user has permission to reply to this discussion. First,
+        // make sure the discussion exists and that the user has permission to
+        // view it; if not, fail with a ModelNotFound exception so we don't give
+        // away the existence of the discussion. If the user is allowed to view
+        // it, check if they have permission to reply.
+        $discussion = $this->discussions->findOrFail($command->discussionId, $actor);
+
+        // If this is the first post in the discussion, it's technically not a
+        // "reply", so we won't check for that permission.
+        if ($discussion->number_index > 0) {
+            $this->assertCan($actor, 'reply', $discussion);
+        }
+
+        // Create a new Post entity, persist it, and dispatch domain events.
+        // Before persistence, though, fire an event to give plugins an
+        // opportunity to alter the post entity based on data in the command.
+        $post = CommentPost::reply(
+            $discussion->id,
+            array_get($command->data, 'attributes.content'),
+            $actor->id,
+            $command->ipAddress
+        );
+
+        if ($actor->isAdmin() && ($time = array_get($command->data, 'attributes.time'))) {
+            $post->time = new DateTime($time);
+        }
+
+        $this->events->fire(
+            new Saving($post, $actor, $command->data)
+        );
+
+        $this->validator->assertValid($post->getAttributes());
+
+        $post->save();
+
+        $this->notifications->onePerUser(function () use ($post, $actor) {
+            $this->dispatchEventsFor($post, $actor);
+        });
+
+        return $post;
+    }
+}