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 bouncing-ball.js <device-ip> [port] [pixels] [interval-ms]');
  process.exit(1);
}

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

let position = Math.random() * (pixels - 1);
let velocity = randomVelocity();

function randomVelocity() {
  const min = 0.15;
  const max = 0.4;
  const sign = Math.random() < 0.5 ? -1 : 1;
  return (min + Math.random() * (max - min)) * sign;
}

function rebound(sign) {
  velocity = randomVelocity() * sign;
}

function mix(a, b, t) {
  return a + (b - a) * t;
}

function generateFrame() {
  const dt = intervalMs / 1000;
  position += velocity * dt * 60; // scale velocity to 60 FPS reference

  if (position < 0) {
    position = -position;
    rebound(1);
  } else if (position > pixels - 1) {
    position = (pixels - 1) - (position - (pixels - 1));
    rebound(-1);
  }

  const activeIndex = Math.max(0, Math.min(pixels - 1, Math.round(position)));

  let payload = 'RAW:';
  for (let i = 0; i < pixels; i++) {
    if (i === activeIndex) {
      payload += 'ff8000';
      continue;
    }

    const distance = Math.abs(i - position);
    const intensity = Math.max(0, 1 - distance);
    const green = Math.round(mix(20, 200, intensity)).toString(16).padStart(2, '0');
    const blue = Math.round(mix(40, 255, intensity)).toString(16).padStart(2, '0');
    payload += '00' + green + blue;
  }

  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 bouncing ball pattern to ${host}:${port} with ${pixels} pixels (interval=${intervalMs}ms)`);