require_relative 'error'
require 'multi_json'

module Contentful
  module Management
    # An object representing an answer by the contentful service. It is later used
    # to build a Resource, which is done by the ResourceBuilder.
    #
    # The Response parses the http response (as returned by the underlying http library) to
    # a JSON object. Responses can be asked the following methods:
    # - #raw (raw HTTP response by the HTTP library)
    # - #object (the parsed JSON object)
    # - #request (the request the response is refering to)
    #
    # It also sets a #status which can be one of:
    # - :ok (seems to be a valid resource object)
    # - :contentful_error (valid error object)
    # - :not_contentful (valid json, but missing the contentful's sys property)
    # - :unparsable_json (invalid json)
    #
    # Error Repsonses also contain a:
    # - :error_message
    class Response
      attr_reader :raw, :object, :status, :error_message, :request

      def initialize(raw, request = nil)
        @raw = raw
        @request = request
        @status = :ok

        if valid_http_response?
          parse_json!
        elsif no_content_response?
          @status = :no_content
        elsif resource_error?
          parse_contentful_error
        elsif service_unavailable_response?
          service_unavailable_error
        else
          parse_http_error
        end
      end

      private

      def error_object?
        object['sys']['type'] == 'Error'
      end

      def parse_contentful_error
        @object = load_json
        @error_message = object['message'] if error_object?
        parse_http_error
      end

      def valid_http_response?
        [200, 201].include?(raw.status)
      end

      def service_unavailable_response?
        @raw.status == 503
      end

      def service_unavailable_error
        @status = :error
        @error_message = 'Service Unavailable, contenful.com API seems to be down'
        @object = Error[@raw.status].new(self)
      end

      def parse_http_error
        @status = :error
        @object = Error[raw.status].new(self)
      end

      def resource_error?
        [400, 404, 422, 429].include?(raw.status)
      end

      def no_content_response?
        raw.to_s == '' && raw.status == 204
      end

      def parse_json!
        @object = load_json
      rescue MultiJson::LoadError => error
        @error_message = error.message
        UnparsableJson.new(self)
      end

      def load_json
        MultiJson.load(unzip_response(raw))
      end

      def unzip_response(response)
        parsed_response = response.to_s
        if response.headers['Content-Encoding'].eql?('gzip')
          sio = StringIO.new(parsed_response)
          gz = Zlib::GzipReader.new(sio)
          gz.read
        else
          parsed_response
        end
      end
    end
  end
end