const HMUARTLGW_DST_OS = 0
const HMUARTLGW_DST_APP = '1'

const crc = function (message) {
  var $crc = 0xd77f
  var buf = Buffer.from(message, 'hex')
  for (var byte of buf) {
    $crc ^= (byte << 8) & 0xff00
    for (var $i = 0; $i < 8; $i++) {
			if ($crc & 0x8000) {
				$crc = ($crc << 1) & 0xffff
				$crc ^= 0x8005
			} else {
				$crc = ($crc << 1) & 0xffff
			}
    }
  }
  return $crc.toString(16)
}

let leading = 'fd00'
let dst = String('0' + String(HMUARTLGW_DST_APP))
let msgCountPerDevice = 0
let msgCountPerCoordinator = 19
let length = 0
let filler = '000000'
let payload = `A0 11 670A2A 19C4DB 0201 C8 0000`.replace(/ /g, '').toString('hex')

// increase counter
msgCountPerDevice = parseInt(msgCountPerDevice + 1, 10)
msgCountPerCoordinator = parseInt(msgCountPerCoordinator + 1, 10)

// calculate length
length = ((payload.length + 2) / 2)

// get hex values from counter
let msgCountPerDeviceHex = parseInt(msgCountPerDevice, 10).toString(16)
let msgCountPerCoordinatorHex = parseInt(msgCountPerCoordinator, 10).toString(16)

if (msgCountPerDeviceHex.length === 1) {
  msgCountPerDeviceHex = '0' + msgCountPerDeviceHex
}

if (msgCountPerCoordinatorHex.length === 1) {
  msgCountPerCoordinatorHex = '0' + msgCountPerCoordinatorHex
}

// build frame
let frame = `${leading} ${length} ${dst} ${msgCountPerCoordinatorHex} 02 ${filler} ${msgCountPerDeviceHex} ${payload}`.replace(/ /g, '')

// calculate crc
frame += crc(frame)

const net = require('net');
const client = net.createConnection({ port: 9000, host: '192.168.178.95' }, () => {
  // 'connect' listener
  console.log('connected to server!');
  console.log(Buffer.from(frame, 'hex'))
  client.write(Buffer.from(frame, 'hex'));
  //client.write(Buffer.from('fd00030001009e03', 'hex'));
  //client.write(Buffer.from('fd00030002039409', 'hex'));
});
client.on('data', (data) => {
  console.log(data.toString())
});
client.on('end', () => {
  console.log('disconnected from server');
})

// C: fd00 03 0001 009e03
// D: fd00 0e 0001 0402 436f5f4350555f417070

// C: fd00 03 0002 039409
// D: fd00 04 0002 04011916 -> ?
// D: fd00 0d 000000 436f -> Co
// D: 5f4350555f417070d831 -> CPU_APP
// D: fd00 12 0100 050000 -> ?
// D 26a186701ac33300000000ef3fa001