var dgram = require('dgram');
var protocol = require('./protocol');
var BufferReader = require('buffer-reader');


var responseHandlers = {};

function registerResponseHandler(command, callback)
{
  if (!responseHandlers.hasOwnProperty(command))
    responseHandlers[command] = [callback];
  else
    responseHandlers[command].push(callback);
}


function callResponseHandlers(command, reader, error)
{
  if (!responseHandlers.hasOwnProperty(command))
    return;

  newHandlers = [];
  responseHandlers[command].forEach(function(callback)
  {
    if (!callback(reader, error))
      newHandlers.push(callback);
  });

  responseHandlers[command] = newHandlers;
}


var serverHost = '';
var serverPort = 0;

var client = dgram.createSocket('udp4');
client.on('message', function (message, remote)
{
  console.log(message.toString('hex'));
  if (message.length < 2)
    return;

  var reader = new BufferReader(message);

  if (reader.nextInt8() !== protocol.Command.Reply)
    return;

  var command = reader.nextInt8();
  if (command === protocol.Command.Error)
    callResponseHandlers(reader.nextInt8(), reader, true)
  else
    callResponseHandlers(command, reader, false);
});


function requestResponse(buffer, callback)
{
  if (buffer === null || buffer.length == 0) return;
  console.log('> ' + buffer.toString('hex'));

  var command = buffer.readInt8(0);
  var cancelled = false;

  var timeout = setTimeout(function()
  {
    cancelled = true;
    callback(null, true);
    clearTimeout(timeout);
  }, 2000);

  registerResponseHandler(command, function(reader, error)
  {
    if (cancelled) return;
    clearTimeout(timeout);

    callback(reader, error);
    return true;
  });

  client.send(buffer, 0, buffer.length, serverPort, serverHost, function(err, bytes)
  {
    if (err)
      onError();
  });
}


function readModeData(mode, reader)
{
  switch (mode)
  {
    case protocol.Mode.Static:
      return {
        brightness: reader.nextInt16LE()
      };

    case protocol.Mode.Custom:
      var values = [];
      while (reader.tell() < reader.buf.length)
        values.push(reader.nextInt16LE());

      return {
        brightness: values
      };

    case protocol.Mode.Alternate:
      return {
        interval: reader.nextInt16LE(),
        brightness: reader.nextInt16LE()
      };

    case protocol.Mode.Slide:
      return {
        interval: reader.nextInt16LE(),
        brightness: reader.nextInt16LE(),
        direction: reader.nextInt8(),
        fadeOutTime: reader.nextInt16LE()
      };
  }

  return null;
}


function lsb(value) { return value & 0xFF; }
function msb(value) { return (value >> 8) & 0xFF; }

function writeModeData(mode, data)
{
  switch (mode)
  {
    case protocol.Mode.Static:
      if (typeof(data.brightness) == 'undefined') data.brightness = 0;

      return new Buffer([protocol.Command.SetMode, mode, lsb(data.brightness), msb(data.brightness)]);

    case protocol.Mode.Custom:
      var brightness = typeof(data.brightness) !== 'undefined' ? data.brightness.split(',') : [];

      var valueCount = Math.min(16, brightness.length);
      var buffer = Buffer.alloc(2 + (valueCount * 2));
      buffer.writeInt8(protocol.Command.SetMode, 0);
      buffer.writeInt8(mode, 1);

      for (var index = 0; index < valueCount; index++)
        buffer.writeInt16LE(brightness[index], 2 + (index * 2));

      return buffer;

    case protocol.Mode.Alternate:
      if (typeof(data.brightness) == 'undefined') data.brightness = 0;
      if (typeof(data.interval) == 'undefined') data.interval = 500;

      return new Buffer([protocol.Command.SetMode, mode,
                         lsb(data.interval), msb(data.interval),
                         lsb(data.brightness), msb(data.brightness)]);

    case protocol.Mode.Slide:
      if (typeof(data.brightness) == 'undefined') data.brightness = 0;
      if (typeof(data.interval) == 'undefined') data.interval = 500;
      if (typeof(data.direction) == 'undefined') data.direction = 0;
      if (typeof(data.fadeOutTime) == 'undefined') data.fadeOutTime = 0;

      return new Buffer([protocol.Command.SetMode, mode,
                         lsb(data.interval), msb(data.interval),
                         lsb(data.brightness), msb(data.brightness),
                         data.direction,
                         lsb(data.fadeOutTime), msb(data.fadeOutTime)]);
  }
}


module.exports =
{
  init: function(host, port)
  {
    serverHost = host;
    serverPort = port;
  },


  ping: function(callback)
  {
    requestResponse(new Buffer([protocol.Command.Ping]),
      function(reader, error)
      {
        if (!error)
        {
          callback(
          {
            stepCount: reader.nextInt8()
          }, false);
        }
        else
          callback(null, true);
      });
  },

  getMode: function(callback)
  {
    requestResponse(new Buffer([protocol.Command.GetMode]),
      function(reader, error)
      {
        if (!error)
        {
          var data = { mode: reader.nextInt8() };
          data.data = readModeData(data.mode, reader);
          callback(data, false);
        }
        else
          callback(null, true);
      });
  },

  setMode: function(mode, data, callback)
  {
    if (!protocol.Mode.hasOwnProperty(mode))
      return;

    requestResponse(writeModeData(protocol.Mode[mode], data),
      function(reader, error)
      {
        if (!error)
        {
          var data = { mode: reader.nextInt8() };
          data.data = readModeData(data.mode, reader);
          callback(data, false);
        }
        else
          callback(null, true);
      });
  }
}