Express Server

import http from "http";
import express from "express";
import cors from "cors";
import helmet from "helmet";

const app = express();
const server = http.createServer(app);

// Track active connections for graceful shutdown
const sockets = new Set<import("net").Socket>();

server.on("connection", (socket) => {
  sockets.add(socket);
  socket.on("close", () => sockets.delete(socket));
});

// Middleware
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(cors());
app.use(helmet());

// Health check endpoint
app.get("/health", (_req, res) => {
  res.status(200).json({ status: "ok", timestamp: new Date().toISOString() });
});

// TODO: Add your routes here
// app.use("/api", yourRouter);

// 404 handler
app.use((_req, res) => {
  res.status(404).json({ success: false, message: "Resource not found" });
});

// Error handler
app.use((err: Error, _req: express.Request, res: express.Response, _next: express.NextFunction) => {
  console.error("[ERROR]", err.stack || err.message);
  res.status(500).json({
    success: false,
    message: process.env.NODE_ENV === "development" ? err.message : "Internal Server Error",
  });
});

const PORT = process.env.PORT || 3000;

export const startServer = async () => {
  if (server.listening) {
    console.log("Server already running");
    return;
  }

  try {
    server.listen(PORT, () => {
      console.log(`Server running on http://localhost:${PORT}`);
      console.log(`Health check: http://localhost:${PORT}/health`);
    });
  } catch (err) {
    console.error("Failed to start server:", err);
    process.exit(1);
  }
};

export const shutdown = async (signal: string) => {
  console.log(`\n${signal} received. Shutting down gracefully...`);

  server.close(() => {
    console.log("HTTP server closed");
    process.exit(0);
  });

  // Force shutdown after 10s
  setTimeout(() => {
    console.warn(
      `Grace period expired. Forcing close of ${sockets.size} remaining connection(s).`
    );
    sockets.forEach((socket) => socket.destroy());
    process.exit(1);
  }, 10000).unref();
};


/* usage

import { startServer, shutdown } from "@libs/server";
 

startServer();

process.on("SIGTERM", () => shutdown("SIGTERM"));
process.on("SIGINT", () => shutdown("SIGINT"));

process.on("unhandledRejection", (reason, p) => {
  console.error("Unhandled Rejection at:", p, "reason:", reason);
});

process.on("uncaughtException", (err) => {
  console.error("Uncaught Exception:", err);
  process.exit(1);
});

*/