protected static function addCssFileToGroup($path, $groupId)
 {
     // create Files Model
     $objFile = new \File($path);
     if (!in_array(strtolower($objFile->extension), array('css', 'less'))) {
         return false;
     }
     $objFile->close();
     $objFileModel = new ExtCssFileModel();
     $objFileModel->pid = $groupId;
     $objFileModel->tstamp = time();
     $objNextSorting = \Database::getInstance()->prepare("SELECT MAX(sorting) AS sorting FROM tl_extcss_file WHERE pid=?")->execute($groupId);
     $objFileModel->sorting = intval($objNextSorting->sorting) + 64;
     $objFileModel->src = $objFile->getModel()->uuid;
     $objFileModel->save();
     return $objFileModel;
 }
 protected function addCssFiles()
 {
     $objFiles = ExtCssFileModel::findMultipleByPids($this->ids, array('order' => 'FIELD(pid, ' . implode(",", $this->ids) . '), sorting DESC'));
     if ($objFiles === null) {
         return false;
     }
     while ($objFiles->next()) {
         $objFileModel = \FilesModel::findByPk($objFiles->src);
         if ($objFileModel === null) {
             continue;
         }
         if (!file_exists(TL_ROOT . '/' . $objFileModel->path)) {
             continue;
         }
         $objFile = new \File($objFileModel->path);
         if ($objFile->size == 0) {
             continue;
         }
         if ($this->isFileUpdated($objFile, $this->objUserCssFile)) {
             $this->rewrite = true;
         }
         $this->objLess->parseFile($objFile->value);
     }
 }