From f0adb6a120c5e48320d227855aec2a1d68e0e1fa Mon Sep 17 00:00:00 2001
From: Alexander Skvortsov <38059171+askvortsov1@users.noreply.github.com>
Date: Mon, 13 Apr 2020 04:45:34 -0400
Subject: [PATCH] Add event extender (used for domain events) (#2097)

---
 framework/core/src/Extend/Event.php           | 45 ++++++++++
 .../tests/integration/extenders/EventTest.php | 84 +++++++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 framework/core/src/Extend/Event.php
 create mode 100644 framework/core/tests/integration/extenders/EventTest.php

diff --git a/framework/core/src/Extend/Event.php b/framework/core/src/Extend/Event.php
new file mode 100644
index 000000000..0f98ca6b9
--- /dev/null
+++ b/framework/core/src/Extend/Event.php
@@ -0,0 +1,45 @@
+<?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\Extend;
+
+use Flarum\Extension\Extension;
+use Illuminate\Contracts\Container\Container;
+use Illuminate\Events\Dispatcher;
+
+class Event implements ExtenderInterface
+{
+    private $listeners = [];
+
+    /**
+     * Add a listener to a domain event dispatched by flarum or a flarum extension.
+     *
+     * The listener can either be:
+     *  - a callback function or
+     *  - the class attribute of a class with a public `handle` method, which accepts an instance of the event as a parameter
+     *
+     * @param string $event
+     * @param callable $listener
+     */
+    public function listen(string $event, $listener)
+    {
+        $this->listeners[] = [$event, $listener];
+
+        return $this;
+    }
+
+    public function extend(Container $container, Extension $extension = null)
+    {
+        $events = $container->make(Dispatcher::class);
+
+        foreach ($this->listeners as $listener) {
+            $events->listen($listener[0], $listener[1]);
+        }
+    }
+}
diff --git a/framework/core/tests/integration/extenders/EventTest.php b/framework/core/tests/integration/extenders/EventTest.php
new file mode 100644
index 000000000..71466db16
--- /dev/null
+++ b/framework/core/tests/integration/extenders/EventTest.php
@@ -0,0 +1,84 @@
+<?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\Tests\integration\extenders;
+
+use Flarum\Extend;
+use Flarum\Group\Event\Created;
+use Flarum\Group\Group;
+use Flarum\Tests\integration\TestCase;
+use Illuminate\Contracts\Events\Dispatcher;
+use Illuminate\Contracts\Translation\Translator;
+
+class EventTest extends TestCase
+{
+    protected function buildGroup()
+    {
+        $events = $this->app()->getContainer()->make(Dispatcher::class);
+
+        $group = Group::build('test group', 'test groups', '#000000', 'fas fa-crown');
+        $group->save();
+
+        $events->dispatch(new Created($group));
+
+        return $group;
+    }
+
+    /**
+     * @test
+     */
+    public function custom_listener_doesnt_work_by_default()
+    {
+        $group = $this->buildGroup();
+
+        $this->assertEquals($group->name_singular, 'test group');
+    }
+
+    /**
+     * @test
+     */
+    public function custom_listener_works_with_closure()
+    {
+        $this->extend((new Extend\Event)->listen(Created::class, function (Created $event) {
+            $event->group->name_singular = 'modified group';
+        }));
+
+        $group = $this->buildGroup();
+
+        $this->assertEquals($group->name_singular, 'modified group');
+    }
+
+    /**
+     * @test
+     */
+    public function custom_listener_works_with_class_with_handle_method_and_can_inject_stuff()
+    {
+        // Because it injects a translator, this also tests that stuff can be injected into this callback.
+        $this->extend((new Extend\Event)->listen(Created::class, CustomListener::class));
+
+        $group = $this->buildGroup();
+
+        $this->assertEquals($group->name_singular, 'core.group.admin');
+    }
+}
+
+class CustomListener
+{
+    protected $translator;
+
+    public function __construct(Translator $translator)
+    {
+        $this->translator = $translator;
+    }
+
+    public function handle(Created $event)
+    {
+        $event->group->name_singular = $this->translator->trans('core.group.admin');
+    }
+}