"""Health reflects a live event loop and a usable database connection."""
import asyncio
import logging
import os
import threading
import time
from pathlib import Path

from sqlalchemy import text

from .database import async_session_maker

HEARTBEAT = Path(os.getenv("HEARTBEAT_FILE", "/tmp/lottery-heartbeat"))


async def heartbeat():
    while True:
        async with asyncio.timeout(20):
            async with async_session_maker() as session:
                await session.execute(text("SELECT 1"))
        pending = HEARTBEAT.with_name(HEARTBEAT.name + ".tmp")
        pending.write_text(str(time.time()), encoding="ascii")
        pending.replace(HEARTBEAT)
        await asyncio.sleep(10)


def healthy():
    try:
        return 0 <= time.time() - float(HEARTBEAT.read_text(encoding="ascii")) < 60
    except (OSError, ValueError):
        return False


def start_watchdog(grace_seconds=75, interval=10):
    """Exit even when the event loop or driver cancellation itself is stuck."""
    stopped = threading.Event()
    started = time.monotonic()

    def watch():
        while not stopped.wait(interval):
            if time.monotonic() - started >= grace_seconds and not healthy():
                logging.getLogger(__name__).critical("Heartbeat expired; restarting the application")
                os._exit(1)

    threading.Thread(target=watch, name="heartbeat-watchdog", daemon=True).start()
    return stopped


if __name__ == "__main__":
    raise SystemExit(0 if healthy() else 1)