"""Keep a passing UI marker from hiding a target JVM's native fatal report."""
from pathlib import Path
import os
import subprocess
import time


class NativeCrashGuard:
    def __init__(self, directory):
        self.directory = Path(directory)
        self.before = {p: p.stat().st_mtime_ns for p in self.directory.glob("hs_err_pid*.log")}

    def check(self):
        reports = [p for p in self.directory.glob("hs_err_pid*.log")
                   if self.before.get(p) != p.stat().st_mtime_ns]
        if reports:
            raise AssertionError("Native JVM crash reports: " + ", ".join(map(str, reports)))


def descendant_workers(owner):
    rows = subprocess.check_output(["ps", "-axo", "pid=,ppid=,command="], text=True)
    processes = {}
    for line in rows.splitlines():
        fields = line.strip().split(None, 2)
        if len(fields) == 3:
            processes[int(fields[0])] = (int(fields[1]), fields[2])
    descendants = {owner}
    while True:
        found = {pid for pid, (parent, _) in processes.items() if parent in descendants}
        if found <= descendants:
            break
        descendants |= found
    return {pid for pid in descendants if pid in processes
            and "de.neitzel.fxdesigner.target.WorkerMain" in processes[pid][1]}


def await_worker_exit(pids):
    pending = set(pids)
    deadline = time.monotonic() + 10
    while pending and time.monotonic() < deadline:
        for pid in tuple(pending):
            try:
                os.kill(pid, 0)
            except ProcessLookupError:
                pending.remove(pid)
        if pending:
            time.sleep(.05)
    if pending:
        raise AssertionError("Workers survived owner shutdown: " + str(sorted(pending)))