const dgram = require('dgram');

const {
  clamp,
  createFrame,
  fadeFrame,
  frameToPayload,
  hexToRgb,
  samplePalette,
  toIndex,
} = require('./shared-frame-utils');

const DEFAULT_PORT = 4210;
const DEFAULT_WIDTH = 16;
const DEFAULT_HEIGHT = 16;
const DEFAULT_INTERVAL_MS = 45;
const DEFAULT_METEOR_COUNT = 12;
const BASE_SPEED_MIN = 4;
const BASE_SPEED_MAX = 10;
const TRAIL_DECAY = 0.76;

const paletteStops = [
  { stop: 0.0, color: hexToRgb('0a0126') },
  { stop: 0.3, color: hexToRgb('123d8b') },
  { stop: 0.7, color: hexToRgb('21c7d9') },
  { stop: 1.0, color: hexToRgb('f7ffff') },
];

const host = process.argv[2];
const port = parseInt(process.argv[3] || String(DEFAULT_PORT), 10);
const width = parseInt(process.argv[4] || String(DEFAULT_WIDTH), 10);
const height = parseInt(process.argv[5] || String(DEFAULT_HEIGHT), 10);
const intervalMs = parseInt(process.argv[6] || String(DEFAULT_INTERVAL_MS), 10);
const meteorCount = parseInt(process.argv[7] || String(DEFAULT_METEOR_COUNT), 10);

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

if (Number.isNaN(port) || Number.isNaN(width) || Number.isNaN(height) || Number.isNaN(intervalMs) || Number.isNaN(meteorCount)) {
  console.error('Invalid numeric argument. Expected integers for port, width, height, interval-ms, and meteor-count.');
  process.exit(1);
}

if (width <= 0 || height <= 0) {
  console.error('Matrix dimensions must be positive integers.');
  process.exit(1);
}

if (meteorCount <= 0) {
  console.error('Meteor count must be a positive integer.');
  process.exit(1);
}

const socket = dgram.createSocket('udp4');
const isBroadcast = host === '255.255.255.255' || host.endsWith('.255');
const frame = createFrame(width, height);
const meteors = createMeteors(meteorCount, width, height);
const frameTimeSeconds = intervalMs / 1000;

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

socket.on('error', (error) => {
  console.error('Socket error:', error.message);
});

function createMeteors(count, matrixWidth, matrixHeight) {
  const meteorList = [];
  for (let index = 0; index < count; ++index) {
    meteorList.push(spawnMeteor(matrixWidth, matrixHeight));
  }
  return meteorList;
}

function spawnMeteor(matrixWidth, matrixHeight) {
  const angle = (Math.PI / 4) * (0.6 + Math.random() * 0.8);
  const speed = BASE_SPEED_MIN + Math.random() * (BASE_SPEED_MAX - BASE_SPEED_MIN);
  return {
    x: Math.random() * matrixWidth,
    y: -Math.random() * matrixHeight,
    vx: Math.cos(angle) * speed,
    vy: Math.sin(angle) * speed,
  };
}

function drawMeteor(meteor) {
  const col = Math.round(meteor.x);
  const row = Math.round(meteor.y);
  if (col < 0 || col >= width || row < 0 || row >= height) {
    return;
  }

  const energy = clamp(1.2 - Math.random() * 0.2, 0, 1);
  frame[toIndex(col, row, width)] = samplePalette(paletteStops, energy);
}

function updateMeteors(deltaSeconds) {
  meteors.forEach((meteor, index) => {
    meteor.x += meteor.vx * deltaSeconds;
    meteor.y += meteor.vy * deltaSeconds;

    drawMeteor(meteor);

    if (meteor.x > width + 1 || meteor.y > height + 1) {
      meteors[index] = spawnMeteor(width, height);
    }
  });
}

function generateFrame() {
  fadeFrame(frame, TRAIL_DECAY);
  updateMeteors(frameTimeSeconds);
  return frameToPayload(frame);
}

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

setInterval(sendFrame, intervalMs);

console.log(
  `Streaming meteor rain to ${host}:${port} (${width}x${height}, interval=${intervalMs}ms, meteors=${meteorCount})`,
);