#!/usr/bin/env python3
"""Minimal NFQUEUE example: add random delay and jitter, but do not drop packets."""

import random
import signal
import sys
import time

from netfilterqueue import NetfilterQueue

# Demo tuning values.
BASE_DELAY_MS = 40
JITTER_MS = 120

nfq = NetfilterQueue()


def _handle_packet(packet) -> None:
    delay_ms = BASE_DELAY_MS + random.uniform(0, JITTER_MS)
    time.sleep(delay_ms / 1000.0)
    packet.accept()


def _stop(_sig, _frame) -> None:
    raise SystemExit(0)


def main() -> int:
    if len(sys.argv) != 2:
        print("Usage: chaos_delay_jitter.py <qnum>", 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.bind(qnum, _handle_packet)
    try:
        nfq.run()
    except KeyboardInterrupt:
        pass
    finally:
        nfq.unbind()

    return 0


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