e_g__singelton,api,faraday.rb

# frozen_string_literal: true

# require 'singleton'... A pattern that restricts the
# instantiation of a class to one object.
# ...when you need an object specifically to hold state
# ...to make sure that each of these services are always
# wrapped in your own interface
# #new constructor condemded

require 'singleton'

module AppName
  module PaymentGatewayName
    # Realization of Singleton pattern
    class Configuration
      include Singleton

      attr_accessor :base_uri, :subscription_id,
                    :merchant_pin, :server_host, :account_id
    end
  end
end

module AppName
  module PaymentGatewayName
    # Our API
    module API
      # how the library will get configured
      def self.configure
        yield(configuration) if block_given?
      end

      # Configuration.instance - this is only one method to gain access
      def self.configuration
        Configuration.instance
      end

      # https://github.com/lostisland/faraday
      # https://stackoverflow.com/a/16548003
      # https://gist.github.com/mislav/938183
      # https://www.mobomo.com/2012/03/faraday-one-http-client-to-rule-them-all/
      # https://github.com/lostisland/faraday_middleware
      #
      # Definiition of the "connection" method that use our Configuration singleton
      def self.connection
        url = configuration.base_url
        @connection ||= Faraday.new(url) do |conn|
          conn.request :url_encoded
          conn.response :ox
          conn.adapter Faraday.default_adapter
        end
      end
    end
  end
end

AppName::PaymentGatewayName::API.configure do |config|
  config.account_id      = ENV.fetch('PAYMENTGATEWAY_ACCOUNT_ID')
  config.base_uri        = ENV.fetch('PAYMENTGATEWAY_BASE_URI')
  config.merchant_pin    = ENV.fetch('PAYMENTGATEWAY_MERCHANT_PIN')
  config.server_host     = ENV.fetch('PAYMENTGATEWAY_SERVER_HOST')
  config.subscription_id = ENV.fetch('PAYMENTGATEWAY_SUBSCRIPTION_ID')
end