class CommandBuilder
{
    public function __construct()
    {
        //
    }

    public function login($username, $password)
    {
        $frame = $this->frame();

        $command = $frame->addChild('command');
        $login = $command->addChild('login');
        $login->addChild('username', $username);
        $login->addChild('password', $password);
        $command->addChild('authKey', 'authkey');

        return $frame->asXML();
    }

    public function info($id)
    {
        $frame = $this->frame();

        $command = $frame->addChild('command');
        $login = $command->addChild('product');
        $login->addChild('id', $id);
        $command->addChild('authKey', 'authkey');

        return $frame->asXML();
    }

    protected function frame()
    {
        return new SimpleXMLElement(
            '<app/>'
        );
    }
}