module Pesapal

  class Merchant

    attr_accessor :config, :order_details

    def config
      @config ||= {}
    end

    def order_details
      @order_details ||= {}
    end

    private

      def api_domain
        @api_domain
      end

      def api_endpoints
        @api_endpoints
      end

      def mode
        @mode
      end

      def params
        @params
      end

      def post_xml
        @post_xml
      end

      def token_secret
        @token_secret
      end

    public

      # constructor
      def initialize(mode = Rails.env, path_to_file = nil)

        # initialize
        @params = nil
        @post_xml = nil
        @token_secret = nil

        set_mode mode

        # set the credentials if we have specified a path from which we
        # will access a YAML file with the configurations
        unless path_to_file.nil?
          set_configuration_from_yaml path_to_file
        end

      end

      # generate pesapal order url (often iframed)
      def generate_order_url

        # check if the config is empty, if yes, we try load what was set by the
        # initializer into Pesapal.config
        if config.empty?
          set_configuration Pesapal.config[@mode]
        end

        # build xml with input data, the format is standard so no editing is
        # required
        @post_xml = Pesapal::Post::generate_post_xml @order_details

        # initialize setting of @params (oauth_signature left empty)
        @params = Pesapal::Post::set_parameters(@config[:callback_url], @config[:consumer_key], @post_xml)

        # generate oauth signature and add signature to the request parameters
        @params[:oauth_signature] = Pesapal::Oauth::generate_oauth_signature("GET", @api_endpoints[:postpesapaldirectorderv4], @params, @config[:consumer_secret], @token_secret)

        # change params (with signature) to a query string
        query_string = Pesapal::Oauth::generate_encoded_params_query_string @params

        "#{@api_endpoints[:postpesapaldirectorderv4]}?#{query_string}"
      end

      # query the details of the transaction
      def query_payment_details(merchant_reference, transaction_tracking_id)

        # check if the config is empty, if yes, we try load what was set by the
        # initializer into Pesapal.config
        if config.empty?
          set_configuration Pesapal.config[@mode]
        end

        # initialize setting of @params (oauth_signature left empty)
        @params = Pesapal::Details::set_parameters(@config[:consumer_key], merchant_reference, transaction_tracking_id)

        # generate oauth signature and add signature to the request parameters
        @params[:oauth_signature] = Pesapal::Oauth::generate_oauth_signature("GET", @api_endpoints[:querypaymentdetails], @params, @config[:consumer_secret], @token_secret)

        # change params (with signature) to a query string
        query_string = Pesapal::Oauth::generate_encoded_params_query_string @params

        # get status response
        response = Net::HTTP.get(URI("#{@api_endpoints[:querypaymentdetails]}?#{query_string}"))
        response = CGI::parse(response)
        response = response["pesapal_response_data"][0].split(',')

        details = { :method => response[1],
                    :status => response[2],
                    :merchant_reference => response[3],
                    :transaction_tracking_id => response[0] }
      end

      # query the status of the transaction
      def query_payment_status(merchant_reference, transaction_tracking_id = nil)

        # check if the config is empty, if yes, we try load what was set by the
        # initializer into Pesapal.config
        if config.empty?
          set_configuration Pesapal.config[@mode]
        end

        # initialize setting of @params (oauth_signature left empty)
        @params = Pesapal::Status::set_parameters(@config[:consumer_key], merchant_reference, transaction_tracking_id)

        # generate oauth signature and add signature to the request parameters
        @params[:oauth_signature] = Pesapal::Oauth::generate_oauth_signature("GET", @api_endpoints[:querypaymentstatus], @params, @config[:consumer_secret], @token_secret)

        # change params (with signature) to a query string
        query_string = Pesapal::Oauth::generate_encoded_params_query_string @params

        # get status response
        response = Net::HTTP.get(URI("#{@api_endpoints[:querypaymentstatus]}?#{query_string}"))
        response = CGI::parse(response)

        # return the string result of what we want
        response["pesapal_response_data"][0]
      end

      # set mode when called
      def set_mode(mode = Rails.env)

        # convert symbol to string and downcase
        @mode = mode.to_s.downcase

        # set api endpoints depending on the mode
        set_endpoints
      end

      # listen to ipn response
      def ipn_listener(notification_type, merchant_reference, transaction_tracking_id)

        status = query_payment_status(merchant_reference, transaction_tracking_id)

        output = { :status => status }

        if status == "COMPLETED"
          output[:response] = "pesapal_notification_type=CHANGE&pesapal_transaction_tracking_id=#{transaction_tracking_id}&pesapal_merchant_reference=#{merchant_reference}"
        elsif status == "FAILED"
          output[:response] = "pesapal_notification_type=CHANGE&pesapal_transaction_tracking_id=#{transaction_tracking_id}&pesapal_merchant_reference=#{merchant_reference}"
        else
          output[:response] = ""
        end

        output
      end

    private

      # set endpoints
      def set_endpoints

        if @mode == 'production'
          @api_domain = 'https://www.pesapal.com'
        else
          @api_domain = 'http://demo.pesapal.com'
        end

        @api_endpoints = {}
        @api_endpoints[:postpesapaldirectorderv4] = "#{@api_domain}/API/PostPesapalDirectOrderV4"
        @api_endpoints[:querypaymentstatus] = "#{@api_domain}/API/QueryPaymentStatus"
        @api_endpoints[:querypaymentdetails] = "#{@api_domain}/API/QueryPaymentDetails"
      end

      # set credentialts through hash, uses default if nothing is input
      def set_configuration(consumer_details = {})

        # set the configuration
        @config = { :callback_url => 'http://0.0.0.0:3000/pesapal/callback',
                    :consumer_key => '<YOUR_CONSUMER_KEY>',
                    :consumer_secret => '<YOUR_CONSUMER_SECRET>'
                }

        valid_config_keys = @config.keys

        consumer_details.each { |k,v| @config[k.to_sym] = v if valid_config_keys.include? k.to_sym }
      end

      # set configuration through yaml file
      def set_configuration_from_yaml(path_to_file)

        if File.exist?(path_to_file)

          # load file, read it and parse the YAML
          begin
            loaded_config = YAML::load(IO.read(path_to_file))
          rescue Errno::ENOENT
            logger.info("YAML configuration file couldn't be found. Using defaults."); return
          rescue Psych::SyntaxError
            logger.info("YAML configuration file contains invalid syntax. Using defaults."); return
          end

          # pick the correct settings depending on the the mode and set it
          # appropriately. this file is expected to have the settings for
          # development and production
          set_configuration loaded_config[@mode]

        else

          # in this case default values will be set
          set_configuration
        end
      end
  end
end