User Extender (prepareGroups functionality) (#2110)

framework/core/src/Extend/User.php

@@ -15,9 +15,10 @@ use Illuminate\Contracts\Container\Container;
 class User implements ExtenderInterface
 {
     private $displayNameDrivers = [];
+    private $groupProcessors = [];
 
     /**
-     * Add a mail driver.
+     * Add a display name driver.
      *
      * @param string $identifier Identifier for display name driver. E.g. 'username' for UserNameDriver
      * @param string $driver ::class attribute of driver class, which must implement Flarum\User\DisplayName\DriverInterface
@@ -29,10 +30,35 @@ class User implements ExtenderInterface
         return $this;
     }
 
+    /**
+     * Dynamically process a user's list of groups when calculating permissions.
+     * This can be used to give a user permissions for groups they aren't actually in, based on context.
+     * It will not change the group badges displayed for the user.
+     *
+     * @param callable $callable
+     *
+     * The callable can be a closure or invokable class, and should accept:
+     * - \Flarum\User\User $user: the user in question.
+     * - array $groupIds: an array of ids for the groups the user belongs to.
+     *
+     * The callable should return:
+     * - array $groupIds: an array of ids for the groups the user belongs to.
+     */
+    public function permissionGroups(callable $callable)
+    {
+        $this->groupProcessors[] = $callable;
+
+        return $this;
+    }
+
     public function extend(Container $container, Extension $extension = null)
     {
         $container->extend('flarum.user.display_name.supported_drivers', function ($existingDrivers) {
             return array_merge($existingDrivers, $this->displayNameDrivers);
         });
+
+        $container->extend('flarum.user.group_processors', function ($existingRelations) {
+            return array_merge($existingRelations, $this->groupProcessors);
+        });
     }
 }