server.py

import socket
import threading
import argparse

HOST = "0.0.0.0"   # Server binds here (0.0.0.0 = all interfaces)
PORT = 5000        # Default port


def handle_client(conn, addr, clients):
    """Handle incoming messages from a single client and broadcast to others."""
    print(f"[+] Connected: {addr}")
    with conn:
        while True:
            try:
                data = conn.recv(1024)
                if not data:
                    break
                msg = data.decode("utf-8").strip()
                print(f"[{addr}] {msg}")
                # Broadcast to all other clients
                for c in clients:
                    if c is not conn:
                        try:
                            c.sendall(f"{addr}: {msg}\n".encode("utf-8"))
                        except:
                            pass
            except ConnectionResetError:
                break
    print(f"[-] Disconnected: {addr}")
    clients.remove(conn)


def run_server():
    """Start the server and accept clients."""
    clients = []
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.bind((HOST, PORT))
        s.listen()
        print(f"[*] Server listening on {HOST}:{PORT}")
        while True:
            conn, addr = s.accept()
            clients.append(conn)
            threading.Thread(
                target=handle_client, args=(conn, addr, clients), daemon=True
            ).start()


def listen_for_messages(sock):
    """Listen for messages from the server and print them."""
    while True:
        data = sock.recv(1024)
        if not data:
            break
        print(data.decode("utf-8").strip())


def run_client(server_ip):
    """Connect to a server and send/receive messages."""
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.connect((server_ip, PORT))
        print(f"[*] Connected to server at {server_ip}:{PORT}")
        threading.Thread(target=listen_for_messages, args=(s,), daemon=True).start()
        while True:
            msg = input("> ")
            if msg.strip().lower() in {"quit", "exit"}:
                break
            s.sendall((msg + "\n").encode("utf-8"))


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Client/Server Engine")
    parser.add_argument("mode", choices=["server", "client"], help="Run as server or client")
    parser.add_argument("--host", help="Server IP (for client mode)", default="127.0.0.1")
    args = parser.parse_args()

    if args.mode == "server":
        run_server()
    else:
        run_client(args.host)