mathie/sage_pay

module SagePay
  module Server
    class Response

      class_attribute :key_converter, :value_converter, :match_converter, :instance_writer => false

      self.key_converter = {
        "VPSProtocol"  => :vps_protocol,
        "Status"       => :status,
        "StatusDetail" => :status_detail,
      }

      self.value_converter = {
        :status => {
          "OK"        => :ok,
          "MALFORMED" => :malformed,
          "INVALID"   => :invalid,
          "ERROR"     => :error
        }
      }

      self.match_converter = {
        "NOTPROVIDED" => :not_provided,
        "NOTCHECKED"  => :not_checked,
        "MATCHED"     => :matched,
        "NOTMATCHED"  => :not_matched
      }

      attr_reader :vps_protocol, :status, :status_detail

      def self.attr_accessor_if_ok(*attrs)
        attrs.each do |attr|
          define_method(attr) do
            if ok?
              instance_variable_get("@#{attr}")
            else
              raise RuntimeError, "Unable to retrieve #{attr} as the status was #{status} (not OK)."
            end
          end
        end
      end

      def self.from_response_body(response_body)
        attributes = {}

        response_body.each_line do |line|
          key, value = line.split('=', 2)
          unless key.nil? || value.nil?
            value = value.chomp

            converted_key = key_converter[key]
            converted_value = value_converter[converted_key].nil? ? value : value_converter[converted_key][value]

            attributes[converted_key] = converted_value
          end
        end

        new(attributes)
      end

      def initialize(attributes = {})
        attributes.each do |k, v|
          # We're only providing readers, not writers, so we have to directly
          # set the instance variable.
          instance_variable_set("@#{k}", v)
        end
      end

      def ok?
        status == :ok
      end

      def failed?
        !ok?
      end

      def invalid?
        status == :invalid
      end

      def malformed?
        status == :malformed
      end

      def error?
        status == :error
      end
    end
  end
end