#!/usr/bin/env python3
"""Minimal TCP forwarder used by run_e2e.sh when the Docker daemon is remote.

Meshtasticator's interactive simulator always connects to its simulated nodes
at localhost:<port> (lib/interactive.py init_communication). On a Gitea
Actions runner whose Docker daemon is remote (e.g. DOCKER_HOST=tcp://docker.local:2375)
the container-published node ports live on the *daemon* host, not the job's
localhost — so we bind 127.0.0.1:<port> in the job and forward to the daemon
host, restoring the localhost view the simulator (and our e2e tests) expect.

Usage: tcp_forward.py --listen 127.0.0.1:4404 --target docker.local:4404
"""

import argparse
import socket
import threading


def _forward(src: socket.socket, dst: socket.socket):
    try:
        while True:
            data = src.recv(65536)
            if not data:
                break
            dst.sendall(data)
    except OSError:
        pass
    finally:
        try:
            dst.shutdown(socket.SHUT_WR)
        except OSError:
            pass


def _handle(client: socket.socket, target_addr):
    try:
        upstream = socket.create_connection(target_addr, timeout=10)
    except OSError:
        client.close()
        return
    t = threading.Thread(target=_forward, args=(client, upstream), daemon=True)
    t.start()
    _forward(upstream, client)
    client.close()
    upstream.close()


def main():
    ap = argparse.ArgumentParser(description=__doc__)
    ap.add_argument("--listen", required=True, help="local bind, e.g. 127.0.0.1:4404")
    ap.add_argument("--target", required=True, help="forward target, e.g. docker.local:4404")
    args = ap.parse_args()

    lhost, lport = args.listen.rsplit(":", 1)
    thost, tport = args.target.rsplit(":", 1)
    target_addr = (thost, int(tport))

    listener = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    listener.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    listener.bind((lhost, int(lport)))
    listener.listen(16)
    print(f"forwarding {args.listen} -> {args.target}", flush=True)

    while True:
        client, _ = listener.accept()
        threading.Thread(target=_handle, args=(client, target_addr), daemon=True).start()


if __name__ == "__main__":
    main()