public function Summary($SortField = 'DateLastActive', $SortDirection = 'desc', $Limit = 30, $Offset = 0) {
      $this->Title(T('User Summary'));

      // Input validation
      $SortField = !in_array($SortField, array('DateLastActive', 'DateInserted', 'Name')) ? 'DateLastActive' : $SortField;
      $SortDirection = $SortDirection == 'asc' ? 'asc' : 'desc';
      $Limit = is_numeric($Limit) && $Limit < 100 && $Limit > 0 ? $Limit : 30;
      $Offset = is_numeric($Offset) ? $Offset : 0;
      
      // Get user list
      $UserModel = new UserModel();
      $UserData = $UserModel->GetSummary('u.'.$SortField, $SortDirection, $Limit, $Offset);
      $this->SetData('UserData', $UserData);
      
      $this->MasterView = 'empty';
      $this->Render('filenotfound', 'home');
   }