#!/usr/bin/env python3
"""Minimal NFQUEUE example script.

Expected argv:
  argv[1] = queue number
Any extra args are optional.
"""

import logging
import signal
import sys
from typing import Optional

try:
    from netfilterqueue import NetfilterQueue
except Exception as exc:  # pragma: no cover
    print(f"Failed to import netfilterqueue: {exc}", file=sys.stderr)
    sys.exit(2)

logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(message)s")
logger = logging.getLogger("hello-nfqueue")

_running = True


def _stop(_sig: int, _frame: Optional[object]) -> None:
    global _running
    _running = False


def _handle_packet(packet) -> None:
    # This demo accepts all packets and logs basic metadata.
    logger.info("packet id=%s len=%s", packet.get_id(), len(packet.get_payload()))
    packet.accept()


def main() -> int:
    if len(sys.argv) < 2:
        print("Usage: hello_nfqueue.py <qnum> [extra args...]", file=sys.stderr)
        return 1

    try:
        qnum = int(sys.argv[1])
    except ValueError:
        print("qnum must be an integer", file=sys.stderr)
        return 1

    signal.signal(signal.SIGINT, _stop)
    signal.signal(signal.SIGTERM, _stop)

    nfq = NetfilterQueue()
    logger.info("Binding to NFQUEUE %d", qnum)
    nfq.bind(qnum, _handle_packet)

    try:
        while _running:
            nfq.run(block=True)
    except KeyboardInterrupt:
        pass
    finally:
        logger.info("Unbinding NFQUEUE %d", qnum)
        nfq.unbind()

    return 0


if __name__ == "__main__":
    raise SystemExit(main())