#!/usr/bin/env python3
# tractor: structured concurrent "actors".
# Copyright 2018-eternity Tyler Goodlet.
#
# SPDX-License-Identifier: AGPL-3.0-or-later
'''
`tractor-reap` — SC-polite zombie-subactor reaper.

Finds `tractor` subactor processes left alive after a
`pytest` (or any tractor-app) run that failed to fully
cancel its actor tree, then sends SIGINT with a bounded
grace window before escalating to SIGKILL.

Detection modes (auto-selected):

    --parent <pid>  : descendant-mode — kill procs whose
                      PPid == <pid>. Use when a parent
                      is still alive and you want to
                      scope the sweep precisely (e.g.
                      CI wrapper calling in from outside
                      pytest).

    (default)       : orphan-mode — kill procs with
                      PPid==1 (init-reparented) whose
                      cwd matches the repo root AND
                      whose cmdline contains `python`.
                      The cwd filter is what prevents
                      sweeping unrelated init-children.

Usage:

    # after a pytest run crashed/was Ctrl+C'd
    scripts/tractor-reap

    # from inside a still-live supervisor
    scripts/tractor-reap --parent 12345

    # dry-run: list what would be reaped, don't signal
    scripts/tractor-reap -n

'''
import argparse
import pathlib
import subprocess
import sys


def _repo_root() -> pathlib.Path:
    '''
    Use `git rev-parse --show-toplevel` when available;
    fall back to the repo this script lives in.

    '''
    try:
        out: str = subprocess.check_output(
            ['git', 'rev-parse', '--show-toplevel'],
            stderr=subprocess.DEVNULL,
            text=True,
        ).strip()
        return pathlib.Path(out)
    except (subprocess.CalledProcessError, FileNotFoundError):
        return pathlib.Path(__file__).resolve().parent.parent


def main() -> int:
    parser = argparse.ArgumentParser(
        prog='tractor-reap',
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter,
    )
    parser.add_argument(
        '--parent', '-p',
        type=int,
        default=None,
        help='descendant-mode: reap procs with PPid==<pid>',
    )
    parser.add_argument(
        '--grace', '-g',
        type=float,
        default=3.0,
        help='SIGINT grace window in seconds (default 3.0)',
    )
    parser.add_argument(
        '--dry-run', '-n',
        action='store_true',
        help='list matched pids but do not signal',
    )
    args = parser.parse_args()

    # import lazily so `--help` doesn't require the tractor
    # package to be importable (e.g. when running from a
    # shell not inside a venv).
    repo = _repo_root()
    sys.path.insert(0, str(repo))
    from tractor._testing._reap import (
        find_descendants,
        find_orphans,
        reap,
    )

    if args.parent is not None:
        pids: list[int] = find_descendants(args.parent)
        mode: str = f'descendants of PPid={args.parent}'
    else:
        pids = find_orphans(repo)
        mode = f'orphans (PPid=1, cwd={repo})'

    if not pids:
        print(f'[tractor-reap] no {mode} to reap')
        return 0

    if args.dry_run:
        print(f'[tractor-reap] dry-run — {mode}:\n  {pids}')
        return 0

    signalled, survivors = reap(pids, grace=args.grace)
    # exit 0 if everyone exited cleanly, else 1 to signal
    # escalation happened — makes the command useful in
    # CI health-checks and `||`-chaining.
    return 0 if not survivors else 1


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