private function getFileBack($fileType, $allMiraklFiles, $frontFile, $shopId, $tmpFilePath)
    {

        try {
            $backType = $this->getFileBackType($fileType);

            // this file type has no backs
            if (!$backType) {
                return null;
            }

            $files = array_filter(
                $allMiraklFiles,
                function ($aFile) use ($backType) {
                    return $aFile['type'] == $backType;
                }
            );

            // No back has been found in Mirakl files
            if (empty($files)) {
                return null;
            }

            $file = end($files);
            // check if extension of file is correct
            $this->checkExtensionFile($file['file_name'], $file, $shopId);
            // save file
            $tmpFile = $tmpFilePath . '/' . time() . preg_replace("/[^A-Za-z0-9\.]/", '', $file['file_name']);
            file_put_contents($tmpFile, $this->mirakl->downloadDocuments(array($file['id'])));

            return array('filePath' => $tmpFile, 'fileObject' => $file);

        } catch (Exception $e) {
            throw new Exception(
                'Document ' .
                $frontFile['id'] .
                ' (type: ' .
                $fileType .
                ') for Mirakl for shop ' .
                $shopId .
                ' will not be uploaded because file of type ' .
                $backType .
                ' not uploaded in Mirakl or uploaded with wrong extension'
            );
        }
    }