# encoding: ascii-8bit

# Copyright 2014 Ball Aerospace & Technologies Corp.
# All Rights Reserved.
#
# This program is free software; you can modify and/or redistribute it
# under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 3 with
# attribution addendums as found in the LICENSE.txt

require 'cosmos/interfaces/interface'
require 'cosmos/io/udp_sockets'
require 'cosmos/config/config_parser'

module Cosmos

  # Base class for interfaces that send and receive messages over UDP
  class UdpInterface < Interface

    # @param hostname [String] Machine to connect to
    # @param write_dest_port [Integer] Port to write commands to
    # @param read_port [Integer] Port to read telemetry from
    # @param write_src_port [Integer] Port to allow replies if needed
    # @param interface_address [String] If the destination machine represented
    #   by hostname supports multicast, then interface_address is used to
    #   configure the outgoing multicast address.
    # @param ttl [Integer] Time To Live value. The number of intermediate
    #   routers allowed before dropping the packet.
    # @param write_timeout [Integer] Seconds to wait before aborting writes
    # @param read_timeout [Integer] Seconds to wait before aborting reads
    def initialize(hostname,
                   write_dest_port,
                   read_port,
                   write_src_port = nil,
                   interface_address = nil,
                   ttl = 128, # default for Windows
                   write_timeout = 10.0,
                   read_timeout = nil)
      super()

      @hostname = ConfigParser.handle_nil(hostname)
      if @hostname
        @hostname = @hostname.to_s
        @hostname = '127.0.0.1' if @hostname.upcase == 'LOCALHOST'
      end
      @write_dest_port = ConfigParser.handle_nil(write_dest_port)
      @write_dest_port = write_dest_port.to_i if @write_dest_port
      @read_port = ConfigParser.handle_nil(read_port)
      @read_port = read_port.to_i if @read_port
      @write_src_port = ConfigParser.handle_nil(write_src_port)
      @write_src_port = @write_src_port.to_i if @write_src_port
      @interface_address = ConfigParser.handle_nil(interface_address)
      @interface_address = '127.0.0.1' if @interface_address and @interface_address.upcase == 'LOCALHOST'
      @ttl = ttl.to_i
      @ttl = 1 if @ttl < 1
      @write_timeout = ConfigParser.handle_nil(write_timeout)
      @write_timeout = @write_timeout.to_f if @write_timeout
      @read_timeout = ConfigParser.handle_nil(read_timeout)
      @read_timeout = @read_timeout.to_f if @read_timeout
      @write_socket = nil
      @read_socket = nil
      @read_allowed = false unless @read_port
      @write_allowed = false unless @write_dest_port
      @write_raw_allowed = false unless @write_dest_port
    end

    # Creates a new {UdpWriteSocket} if the the write_dest_port was given in
    # the constructor and a new {UdpReadSocket} if the read_port was given in
    # the constructor.
    def connect
      @write_socket = UdpWriteSocket.new(@hostname,
                                         @write_dest_port,
                                         @write_src_port,
                                         @interface_address,
                                         @ttl) if @write_dest_port
      @read_socket = UdpReadSocket.new(@read_port,@hostname,@interface_address) if @read_port
    end

    # @return [Boolean] Whether the active ports (read and/or write) have
    #   created sockets. Since UDP is connectionless, creation of the sockets
    #   is used to determine connection.
    def connected?
      if @write_dest_port && @read_port
        (@write_socket && @read_socket) ? true : false
      elsif @write_dest_port
        @write_socket ? true : false
      else
        @read_socket ? true : false
      end
    end

    # Close the active ports (read and/or write) and set the sockets to nil.
    def disconnect
      Cosmos.close_socket(@write_socket)
      @write_socket = nil
      Cosmos.close_socket(@read_socket)
      @read_socket = nil
    end

    # If the read port was given, the read_socket is read and the data returned
    # in a {Packet}. bytes_read and read_count are updated.
    #
    # @return [Packet]
    def read
      if @read_port
        begin
          data = @read_socket.read(@read_timeout)
          @raw_logger_pair.read_logger.write(data) if @raw_logger_pair
        rescue IOError
          # Disconnected
          Thread.stop
        end

        @bytes_read += data.length
        @read_count += 1

        return Packet.new(nil, nil, :BIG_ENDIAN, nil, data)
      else
        # Write only interface so stop the thread which calls read
        Thread.stop
      end
    end

    # If the write_dest_port was given, the write_socket is written with the
    # packet data. bytes_written and write_count are updated.
    #
    # @param packet [Packet] Packet buffer to write
    def write(packet)
      if @write_dest_port
        if connected?()
          write_raw(packet.buffer)
        else
          raise "Interface not connected"
        end
      else
        raise "Attempt to write to read only interface"
      end
    end

    # If the write_dest_port was given, the write_socket is written with the
    # data. bytes_written and write_count are updated.
    #
    # @param data [String] Raw binary data to write
    def write_raw(data)
      if @write_dest_port
        if connected?()
          @write_socket.write(data, @write_timeout)
          @bytes_written += data.length
          @write_count += 1
          @raw_logger_pair.write_logger.write(data) if @raw_logger_pair
        else
          raise "Interface not connected"
        end
      else
        raise "Attempt to write to read only interface"
      end
    end

  end # class UdpInterface

end # module Cosmos