public function stringify($server, $secret, $original, $commands)
    {
        if (count($commands) > 0) {
            $commandPath = implode('/', $commands);
            $imgPath = sprintf('%s/%s', $commandPath, $original);
        } else {
            $imgPath = $original;
        }

        $signature = $secret ? self::sign($imgPath, $secret) : 'unsafe';

        return sprintf(
            '%s/%s/%s',
            $server,
            $signature,
            $imgPath
        );
    }