module Agcod
  class Request
    def initialize(options = {})
      @request = ""
      @response = ""
      @status = ""
      @parameters = {}
      @options = options
    end

    def submit
      #action must be specified so raise an exception if it has not been populated
      if self.action.nil?
        raise "Action not specified"
      end

      #form the request GET parameter string
      @request = build_sorted_and_signed_request_string

      send_request

      if @response
        process_response
        log if Agcod::Configuration.logger
      end
    end

    def successful?
      self.sent && self.errors.size == 0 && self.status == "SUCCESS"
    end

    attr_reader :errors, :request_id, :sent, :action, :request, :parameters, :response, :xml_response, :status, :timestamp

    def sign_string(string_to_sign)
      digest = OpenSSL::Digest.new('sha256')
      sha256 = OpenSSL::HMAC.digest(digest, Agcod::Configuration.secret_key, string_to_sign)

      #Base64 encoding adds a linefeed to the end of the string so chop the last character!
      CGI.escape(Base64.encode64(sha256).chomp)
    end

    def request_id
      @options["request_id"]
    end

    def response_id
      @response_id || @options["response_id"]
    end

    def request_url
      "#{ Agcod::Configuration.uri }?#{ build_sorted_and_signed_request_string }"
    end

    protected

    def process_response
      parse_response

      @errors = []

      self.xml_response.root.elements.each("Error") do |e|
        @errors << e.elements["Message"].text
      end

      @status = self.xml_response.root.elements["Status/statusCode"].text unless xml_response.root.elements["Status/statusCode"].nil?

      # in some cases we have a failure and no Error elements.  Check for
      # a status message in this case
      if @status == 'FAILURE'
        @errors << self.xml_response.root.elements["Status/statusMessage"].text unless xml_response.root.elements["Status/statusMessage"].nil?
      end

      #something happened before it got to ACGWS (most likely a signature problem)
      @status = "FAILURE" if self.errors.size > 0 && self.status.blank?

      @request_id = xml_response.root.elements["RequestID"].text unless xml_response.root.elements["RequestID"].nil?
    end

    def parse_response
      @xml_response ||= REXML::Document.new(self.response)
    end

    def attempt_retry
      #check for retry error
      if self.xml_response.root.elements["Status/errorCode"] &&
         self.xml_response.root.elements["Status/errorCode"].text == "E100" &&
         ! @sent_retry
      then
        @sent_retry = true
        submit
      end
    end

    def send_request
      #send the request
      uri = URI.parse request_url
      http = Net::HTTP.new(uri.host, uri.port)
      http.read_timeout = 20
      http.open_timeout = 20
      http.use_ssl = true

      if Agcod::Configuration.verify_mode
        http.verify_mode = Agcod::Configuration.verify_mode.constantize
      end

      @response = @xml_response = nil
      net_response, @response = http.get(uri.path + "?" + uri.query)
      @response ||= net_response.read_body

      @sent = true
    end

    def default_parameters
      @timestamp = Time.now.utc
      {
        "Action"                       => self.action,
        "AWSAccessKeyId"               => Agcod::Configuration.access_key,
        "SignatureVersion"             => "2",
        "SignatureMethod"              => "HmacSHA256",
        "MessageHeader.recipientId"    => "AMAZON",
        "MessageHeader.sourceId"       => Agcod::Configuration.partner_id,
        "MessageHeader.retryCount"     => "0",
        "MessageHeader.contentVersion" => "2008-01-01",
        "MessageHeader.messageType"    => self.action + "Request",
        "Timestamp"                    => @timestamp.strftime("%Y-%m-%dT%H:%M:%S") + ".000Z"
      }
    end

    def build_sorted_and_signed_request_string
      params_to_submit = default_parameters.merge(self.parameters).sort
      string_to_sign   = build_v2_string_to_sign(params_to_submit)
      encoded_key_value_strings = []

      params_to_submit.each do |p|
        encoded_value = p[0] =~ /Timestamp/i ? p[1] : CGI.escape(p[1].to_s)
        encoded_key_value_strings << p[0].to_s + "=" + encoded_value
      end

      signature = sign_string(string_to_sign)
      encoded_key_value_strings.insert(encoded_key_value_strings.index("SignatureVersion=2") + 1 , "Signature=" + signature)
      encoded_key_value_strings.join("&")
    end

    def sort_parameters(params)
      params.sort{|a, b| a[0].downcase <=> b[0].downcase }
    end

    def log
      log_string = "[AGCOD] #{self.action} Request"
      log_string << " \##{self.request_id}" if self.request_id
      log_string << " received response #{self.response_id}" if self.response_id
      if self.respond_to?(:claim_code) && self.claim_code
        log_string << " received claim_code #{self.claim_code}"
      end
      Agcod::Configuration.logger.debug log_string
    end

    def build_v2_string_to_sign(parameters)
      parsed_uri = URI.parse(Agcod::Configuration.uri)

      string_to_sign = "GET\n#{parsed_uri.host.downcase}\n#{parsed_uri.request_uri}\n"

      parameters.sort.each_with_index do |v, i|
        string_to_sign << '&' unless i == 0

        string_to_sign << urlencode(v[0])
        string_to_sign << "=#{urlencode(v[1])}" if !v[1].nil?
      end

      return string_to_sign
    end

    def urlencode(plaintext)
      CGI.escape(plaintext.to_s).gsub("+", "%20").gsub("%7E", "~")
    end
  end
end