pesa-pal integration in Rails [incomplete]

pesapal.rb

module PesaPal

  include ActiveSupport::Configurable

  
  self.configure do |config|
    config.test_mode       = !Rails.env.production?
    config.consumer_key    = Rails.env.production? ? "" : ""
    config.consumer_secret = Rails.env.production? ? "" : ""  
    config.merchant_email  = Rails.env.production? ? "" : "[email protected]"
  end
  
end

class TransactionUrl
    
    require 'oauth'
    require 'uri'
    require 'active_support/core_ext/object/to_query'
    
    attr_reader :post_data_xml, :callback_url, :token, :request_options
  
    HTTP_METHOD = 'get'
    API_ACTION = 'API/PostPesapalDirectOrderV4'
    
    def initialize(post_data_xml, callback_url)
      @post_data_xml   = URI.escape(post_data_xml)
      @callback_url    = callback_url
      @token           = nil
      @request_options = {}
    end
    
    def api_domain
      PesaPal.config[:test_mode] ? 'https://demo.pesapal.com' : 'https://www.pesapal.com'
    end
    
    def url
      "#{signed_request.path}&#{joined_params}"
    end
    
    
    def joined_params
      params.to_query
    end
    
    def consumer
      @consumer ||= begin
        OAuth::Consumer.new(PesaPal.config[:consumer_key], PesaPal.config[:consumer_secret], {
          site: api_domain, 
          scheme: :query_string,
          http_method: :get,
        }
        )
      end
    end

    def signed_request
      consumer.create_signed_request(HTTP_METHOD, "#{api_domain}/#{API_ACTION}", token, request_options, params)
    end
    
    def params
      @params = { 
        oauth_callback: URI.escape(callback_url),
        pesapal_request_data: post_data_xml,
      }
    end

end

url = TransactionUrl.new("your xml", "callbackURL").url