code: public function normalizeFile($filepath)
      {
          $pathinfo = pathinfo($filepath);
          switch ($pathinfo['extension']) {
              case 'csv':
                  return $filepath;
              break;
              case 'xls':
                  $tmpfile = Yii::$app->fileStorage->getTempFile();
  
                  return $this->convertExcel($filepath, $tmpfile, 'Excel5');
              break;
              case 'xlsx';
                  $tmpfile = Yii::$app->fileStorage->getTempFile();
  
                  return $this->convertExcel($filepath, $tmpfile);
              break;
          }
      }
docs: [[@doctodo method_description:normalizeFile]].
  
  @param [[@doctodo param_type:filepath]] $filepath [[@doctodo param_description:filepath]]
  
  @return [[@doctodo return_type:normalizeFile]] [[@doctodo return_description:normalizeFile]]