server.js

// Entry point: wires the optional database, the Express REST API, and the
// Socket.IO realtime server together, then starts listening.
//
// Architecture at a glance:
//   - server/app.js            Express REST API (auth + profiles/history)
//   - server/socketHandlers.js Socket.IO realtime gameplay
//   - server/gameStore.js      in-memory active-game state (never hits Mongo)
//   - server/chessRules.js     server-authoritative move validation
//   - utils/persistGame.js     one-time persistence on game-over

require("dotenv").config();

const http = require("http");
const { Server } = require("socket.io");

const { connectDB } = require("./config/db");
const { socketAuth } = require("./middleware/auth");
const { createApp } = require("./server/app");
const { registerSocketHandlers } = require("./server/socketHandlers");

const PORT = process.env.PORT || 5001;

// Concrete origin(s) — required because we use credentialed CORS (cookies).
// "*" is not valid with credentials, so default to the local Next.js dev server.
const CLIENT_ORIGIN = process.env.CLIENT_ORIGIN
  ? process.env.CLIENT_ORIGIN.split(",").map((s) => s.trim())
  : "http://localhost:3000";

// Kick off the (optional) database connection. Gameplay runs regardless.
connectDB();

const app = createApp(CLIENT_ORIGIN);
const server = http.createServer(app);
const io = new Server(server, {
  cors: { origin: CLIENT_ORIGIN, credentials: true },
});

io.use(socketAuth);
registerSocketHandlers(io);

server.listen(PORT, () => console.log(`Server running on port ${PORT}`));