API: Add event for determining user groups for permissions

framework/core/src/Core/Users/User.php

@@ -17,6 +17,7 @@ use Flarum\Events\UserBioWasChanged;
 use Flarum\Events\UserAvatarWasChanged;
 use Flarum\Events\UserWasActivated;
 use Flarum\Events\UserEmailChangeWasRequested;
+use Flarum\Events\GetUserGroups;
 use Flarum\Core\Support\Locked;
 use Flarum\Core\Support\VisibleScope;
 use Flarum\Core\Support\EventGenerator;
@@ -560,6 +561,8 @@ class User extends Model
             $groupIds = array_merge($groupIds, [Group::MEMBER_ID], $this->groups->lists('id'));
         }
 
+        event(new GetUserGroups($this, $groupIds));
+
         return Permission::whereIn('group_id', $groupIds);
     }
 

framework/core/src/Events/GetUserGroups.php

@@ -0,0 +1,29 @@
+<?php namespace Flarum\Events;
+
+use Flarum\Core\Users\User;
+
+/**
+ * The `GetUserGroups` event
+ */
+class GetUserGroups
+{
+    /**
+     * @var User
+     */
+    public $user;
+
+    /**
+     * @var array
+     */
+    public $groupIds;
+
+    /**
+     * @param User $user
+     * @param array $groupIds
+     */
+    public function __construct(User $user, array &$groupIds)
+    {
+        $this->user = $user;
+        $this->groupIds = &$groupIds;
+    }
+}