public function getGatewayUrl()
    {
        switch ($this->getGatewayMode())
        {
            case self::GATEWAY_MODE_SANDBOX:
            {
                return $this->getGatewayUrlSandbox();
            }
            case self::GATEWAY_MODE_PRODUCTION:
            {
                return $this->getGatewayUrlProduction();
            }
            default:
            {
                throw new RuntimeException('You must set gatewayMode property first');
            }
        }
    }