payload_processor.rb

module Sirportly
  module Modules
    module MailHandlers
      class Postal
        # Allows an incoming AppMail messaage to be verified and turned into a ruby object
        class PayloadProcessor
          class InvalidSignatureError < StandardError; end

          attr_reader :request

          # @param [Rack::Request] request Incoming web request containing an email to be processed
          def initialize(request)
            @request = request
          end

          # Verify the payload of the request using the signature in the X-AppMail-Signature HTTP header and the AppMail
          # public key store in APPMAIL_PUBLIC_KEY
          def valid_signature?
            BasicSSL.verify(Sirportly.config.postal_payload_verification_key, signature, raw_payload)
          end

          # Parse the payload in the message
          #
          # @return [Hash] hash representation of the payload
          def payload
            raise InvalidSignatureError unless valid_signature?

            JSON.parse(raw_payload, :symbolize_names => true)
          end

          private

          def raw_payload
            @raw_payload ||= request.body.read
          end

          def signature
            request.headers['X-Postal-Signature']
          end
        end
      end
    end
  end
end