berkes/bitkassa

module Bitkassa
  # A +PaymentResult+ represents the result which is posted to return_url.
  # This callback contains the status of the payment.
  class PaymentResult
    # Contains the payload exactly as posted by Bitkassa
    attr_accessor :raw_payload
    # Contains the authentication_message as posted by Bitkass
    attr_accessor :raw_authentication

    ##
    # Initialize a +PaymentResult+ from a www-url-encoded body.
    def self.from_form_urlencoded(body)
      params = Hash[URI.decode_www_form(body)]
      new(raw_payload: params["p"], raw_authentication: params["a"])
    end

    ##
    # Attributes:
    # +raw_payload+ the original, unencoded string containing the payload.
    # +raw_authentication+ the original string containing the signed message.
    def initialize(attributes)
      attributes.each do |key, value|
        setter_method = "#{key}=".to_sym
        send(setter_method, value)
      end
    end

    ##
    # Gives the extracted payment_id.
    def payment_id
      payload["payment_id"]
    end

    ##
    # Gives the extracted payment_status.
    def payment_status
      payload["payment_status"]
    end

    ##
    # Gives the extracted meta_info.
    def meta_info
      payload["meta_info"]
    end

    ##
    # Wether or not this payment result can be considered valid.
    # Authentication is checked, payload and authentication should be available
    # and the decoded JSON should be valid JSON.
    # When the result is valid, it is safe to assume no-one tampered with it
    # and that it was sent by Bitkassa.
    def valid?
      return false if raw_payload.nil? || raw_payload.empty?
      return false if raw_authentication.nil? || raw_authentication.empty?
      return false unless json_valid?

      Authentication.valid?(raw_authentication, json_payload)
    end

    private

    def payload
      @payload ||= JSON.parse(json_payload)
    end

    def json_payload
      Base64.decode64(raw_payload)
    end

    def json_valid?
      begin
        payload
      rescue JSON::ParserError
        return false
      end
      true
    end
  end
end