G2A Pay - Create payment (Ruby)

On one of my websites, I want to integrate new payment gateway processor G2A Pay. I checked their documentation and it looks pretty easy. The whole process, in general, might be divided into following steps:

Get token by calling API endpoint with payment parameters
Redirect user to specific G2A checkout page using token
Wait for notification sent from G2A server to your server URL (notifications are sent on each transaction status change)

In today's post, I will focus only on the first point. First of all, we need couple configuration parameters. I've extracted them to my application config file (Figaro gem is very helpful for such configurations), so I can have different configurations for each of my environments:

development:
  G2A_API_HASH: hash # get it from G2A Settings -> Merchant
  G2A_API_SECRET: secret # get it from G2A Settings -> Merchant
  G2A_MERCHANT_EMAIL: merchant@youremail.com
  G2A_QUOTE_URL: https://checkout.test.pay.g2a.com/index/createQuote # sandbox endpoint
  G2A_FAILURE_URL: http://my-test-store.com/order/failure
  G2A_OK_URL: http://my-test-store.com/order/success

Now we can proceed to more interesting part. We need to build payload following guides from G2A documentation. For performing POST request I decided to use rest-client gem and digest for hash generation. Here is the first implementation of my class for G2A checkout token generation:

require 'restclient'
require 'digest'

module GA
  class GeneratePayment
    class << self
      def call(order_id, amount, currency, item)
        payload = payment_params(order_id, amount, currency, item)

        post_request(payload)
      end

      private

      def payment_params(order_id, amount, currency, item)
        {
          api_hash:    ENV['G2A_API_HASH'],
          hash:        generate_hash(order_id, amount, currency),
          order_id:    order_id,
          amount:      amount,
          currency:    currency,
          email:       ENV['G2A_MERCHANT_EMAIL'],
          url_failure: ENV['G2A_FAILURE_URL'],
          url_ok:      ENV['G2A_OK_URL'],
          'items[0]' => item
        }
      end

      def generate_hash(order_id, amount, currency)
        string = order_id + amount + currency + ENV['G2A_API_SECRET']
        Digest::SHA256.hexdigest(string)
      end

      def post_request(params)
        begin
          resp = RestClient::Request.execute(method: :post,
                                            url: ENV['G2A_QUOTE_URL'],
                                            payload: params
          resp.body
        rescue => e
          e.response
        end
      end
    end
  end
end

Usage:

item = {"sku"=>"413-1", "name"=>"Diablo 3", "amount"=>"25", "qty"=>"1", "price"=>"100", "id"=>"11203", "url"=>"https://teststore.com/products/11203-Diablo-3"}
GA::GeneratePayment.call('order-1231', '100', 'EUR', item)

Output:

{
"status": "ok",
"token": "854d863124b6db"
}

Now user may be redirected to https://www.test.pay.g2a.com/index/gateway?token=854d863124b6db

In the next iteration, I will improve error handling and allow to pass an array of items to the constructor.

Artur Chmaro

G2A Pay - Create payment (Ruby)