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 speed = parseFloat(process.argv[5] || '0.5'); // cycles per second

if (!host) {
  console.error('Usage: node fade-green-blue.js <device-ip> [port] [pixels] [speed-hz]');
  process.exit(1);
}

const socket = dgram.createSocket('udp4');
const intervalMs = 50;
let tick = 0;
const isBroadcast = host === '255.255.255.255' || host.endsWith('.255');

function generateFrame() {
  const timeSeconds = (tick * intervalMs) / 1000;
  const phase = timeSeconds * speed * Math.PI * 2;
  const blend = (Math.sin(phase) + 1) * 0.5; // 0..1

  const green = Math.round(255 * (1 - blend));
  const blue = Math.round(255 * blend);

  let payload = 'RAW:';
  const gHex = green.toString(16).padStart(2, '0');
  const bHex = blue.toString(16).padStart(2, '0');

  for (let i = 0; i < pixels; i++) {
    payload += '00';
    payload += gHex;
    payload += bHex;
  }

  return payload;
}

function sendFrame() {
  const payload = generateFrame();
  const message = Buffer.from(payload, 'utf8');
  socket.send(message, port, host);
  tick += 1;
}

setInterval(sendFrame, intervalMs);

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

console.log(`Streaming green/blue fade to ${host}:${port} with ${pixels} pixels (speed=${speed}Hz)`);