sova-jam/web/server.js

import { createServer } from "node:http";
import { readFileSync } from "node:fs";
import { Socket } from "node:net";
import { encode, decode } from "@msgpack/msgpack";
import CRC32 from "crc-32";
import { WebSocketServer } from "ws";

const SOVA_HOST = process.env.SOVA_HOST || "localhost";
const SOVA_PORT = parseInt(process.env.SOVA_PORT || "8080");
const SOVA_PASSWORD = process.env.SOVA_PASSWORD || null;
const WEB_PORT = parseInt(process.env.WEB_PORT || "3000");
const PROTOCOL_VERSION = 0x02;

const indexHtml = readFileSync(new URL("./index.html", import.meta.url));

let state = {
  peers: [],
  tempo: 120,
  isPlaying: false,
  connected: false,
};

// --- Wire protocol ---

function buildFrame(msg) {
  const payload = encode(msg);
  const crc = CRC32.buf(payload) >>> 0;
  const len = payload.length;
  const frame = Buffer.alloc(8 + len);
  frame[0] = PROTOCOL_VERSION;
  frame[1] = (len >> 16) & 0xff;
  frame[2] = (len >> 8) & 0xff;
  frame[3] = len & 0xff;
  frame.writeUInt32BE(crc, 4);
  Buffer.from(payload).copy(frame, 8);
  return frame;
}

function parseFrames(buffer) {
  const messages = [];
  let offset = 0;
  while (offset + 8 <= buffer.length) {
    if (buffer[offset] !== PROTOCOL_VERSION) {
      offset++;
      continue;
    }
    const len = (buffer[offset + 1] << 16) | (buffer[offset + 2] << 8) | buffer[offset + 3];
    if (len > 10 * 1024 * 1024) {
      offset++;
      continue;
    }
    if (offset + 8 + len > buffer.length) break;
    const payload = buffer.subarray(offset + 8, offset + 8 + len);
    const expectedCrc = buffer.readUInt32BE(offset + 4);
    const actualCrc = CRC32.buf(payload) >>> 0;
    if (expectedCrc !== actualCrc) {
      offset++;
      continue;
    }
    try {
      messages.push(decode(payload));
    } catch {
      // skip malformed msgpack
    }
    offset += 8 + len;
  }
  return { messages, remaining: buffer.subarray(offset) };
}

// --- TCP client to sova-server ---

let tcp = null;
let reconnectTimer = null;

function connectToSova() {
  if (tcp) return;
  console.log(`Connecting to sova-server at ${SOVA_HOST}:${SOVA_PORT}`);
  const sock = new Socket();
  let recvBuf = Buffer.alloc(0);

  sock.connect(SOVA_PORT, SOVA_HOST, () => {
    console.log("Connected to sova-server");
    const handshake = { SetName: { name: "Web Monitor", password: SOVA_PASSWORD } };
    sock.write(buildFrame(handshake));
  });

  sock.on("data", (chunk) => {
    recvBuf = Buffer.concat([recvBuf, chunk]);
    const { messages, remaining } = parseFrames(recvBuf);
    recvBuf = remaining;
    for (const msg of messages) handleMessage(msg);
  });

  sock.on("close", () => {
    console.log("Disconnected from sova-server");
    tcp = null;
    state.connected = false;
    broadcast();
    scheduleReconnect();
  });

  sock.on("error", (err) => {
    console.error("TCP error:", err.message);
    sock.destroy();
  });

  tcp = sock;
}

function scheduleReconnect() {
  if (reconnectTimer) return;
  reconnectTimer = setTimeout(() => {
    reconnectTimer = null;
    connectToSova();
  }, 3000);
}

function handleMessage(msg) {
  if (msg.Hello) {
    state.connected = true;
    state.peers = msg.Hello.peers || [];
    state.isPlaying = msg.Hello.is_playing || false;
    if (msg.Hello.link_state) state.tempo = msg.Hello.link_state[0];
    broadcast();
  } else if (msg.PeersUpdated) {
    state.peers = msg.PeersUpdated;
    broadcast();
  } else if (msg.PlaybackStateChanged != null) {
    state.isPlaying = !!msg.PlaybackStateChanged;
    broadcast();
  } else if (msg.ClockState) {
    state.tempo = msg.ClockState[0];
    broadcast();
  } else if (msg.ConnectionRefused) {
    console.error("Connection refused:", msg.ConnectionRefused);
  }
}

// --- HTTP + WebSocket ---

const server = createServer((req, res) => {
  if (req.url === "/" || req.url === "/index.html") {
    res.writeHead(200, { "Content-Type": "text/html" });
    res.end(indexHtml);
  } else {
    res.writeHead(404);
    res.end();
  }
});

const wss = new WebSocketServer({ server });
const clients = new Set();

wss.on("connection", (ws) => {
  clients.add(ws);
  ws.send(JSON.stringify(state));
  ws.on("close", () => clients.delete(ws));
});

function broadcast() {
  const data = JSON.stringify(state);
  for (const ws of clients) ws.send(data);
}

server.listen(WEB_PORT, () => {
  console.log(`Web server listening on port ${WEB_PORT}`);
  connectToSova();
});