public function buildHttpRedirect()
    {
        if (!is_null($this->http)) {
            return $this->http;
        }

        $builder   = new ShopgateBuilder($this->initConfig());
        $userAgent = $this->header->getHttpUserAgent();

        try {
            $this->http = $builder->buildHttpRedirect($userAgent, $this->request->getParams(), $_COOKIE);
        } catch (\ShopgateMerchantApiException $e) {
            $this->logger->error('HTTP > oAuth access token for store not set: ' . $e->getMessage());

            return null;
        } catch (\Exception $e) {
            $this->logger->error('HTTP > error in HTTP redirect: ' . $e->getMessage());

            return null;
        }

        return $this->http;
    }