private function operationSftp($operation)
    {
        $config = $this->operationFtpConfig($operation);

        $adapter    = new SftpAdapter($config);
        $filesystem = new Filesystem($adapter);

        $written = false;
        if ($stream = fopen($this->file->getLocation(), 'r+')) {
            $this->setLogs($this->file->getLocation(), 'sftpUploading');
            $written = $filesystem->writeStream($this->file->getName(), $stream);
            if (is_resource($stream)) {
                fclose($stream);
            }
            $this->setLogs($written, 'sftpConfirmed');
            if (!$written) {
                $this->setLogs('Could not confirm file upload via SFTP', 'error');
            } else {
                $this->setLogs($filesystem->has($this->file->getName()), 'sftpConfirmed2');
            }
        } else {
            $this->setLogs('Unable to open file for upload via SFTP.', 'error');
        }

        return $written;
    }