const dgram = require('dgram');

const host = process.argv[2];
const port = parseInt(process.argv[3] || '4210', 10);
const pixels = parseInt(process.argv[4] || '64', 10);
const intervalMs = parseInt(process.argv[5] || '30', 10);

if (!host) {
  console.error('Usage: node rainbow.js <device-ip> [port] [pixels] [interval-ms]');
  process.exit(1);
}

const socket = dgram.createSocket('udp4');
let offset = 0;
const isBroadcast = host === '255.255.255.255' || host.endsWith('.255');

function wheel(pos) {
  pos = 255 - pos;
  if (pos < 85) {
    return [255 - pos * 3, 0, pos * 3];
  }
  if (pos < 170) {
    pos -= 85;
    return [0, pos * 3, 255 - pos * 3];
  }
  pos -= 170;
  return [pos * 3, 255 - pos * 3, 0];
}

function generateFrame() {
  let payload = 'RAW:';
  for (let i = 0; i < pixels; i++) {
    const colorIndex = (i * 256 / pixels + offset) & 255;
    const [r, g, b] = wheel(colorIndex);
    payload += r.toString(16).padStart(2, '0');
    payload += g.toString(16).padStart(2, '0');
    payload += b.toString(16).padStart(2, '0');
  }

  offset = (offset + 1) & 255;
  return payload;
}

function sendFrame() {
  const payload = generateFrame();
  const message = Buffer.from(payload, 'utf8');
  socket.send(message, port, host);
}

setInterval(sendFrame, intervalMs);

if (isBroadcast) {
  socket.bind(() => {
    socket.setBroadcast(true);
  });
}

console.log(`Streaming rainbow pattern to ${host}:${port} with ${pixels} pixels (interval=${intervalMs}ms)`);