/**
  *  Display a list of files available
  *  to the user
  */
 public function actionIndex()
 {
     if (\Yii::$app->user->isGuest) {
         $this->redirect(['/site/index']);
     }
     $user = \Yii::$app->user->identity;
     // Get the list of file groups this user belongs too
     $usergroups = UserFileGroup::find()->where(['user_id' => $user->id])->all();
     // get the list of filegroups
     $files = [];
     foreach ($usergroups as $ug) {
         $groups = FileFileGroup::find()->where(['group_id' => $ug->file_group_id])->all();
         foreach ($groups as $g) {
             array_push($files, $g->file_id);
         }
     }
     $files = File::findAll($files);
     return $this->render('index', ['user' => $user, 'files' => $files]);
 }