"""The scheduler thread: one per process, one tick every 30 seconds (AD-12)."""

from __future__ import annotations

import logging
import threading
from collections.abc import Callable

from django.db import close_old_connections

from . import services

logger = logging.getLogger(__name__)

TICK_SECONDS = 30


class Runner:
    def __init__(self, tick: Callable[[], None] = services.tick, interval: float = TICK_SECONDS):
        self._tick = tick
        self._interval = interval
        self._stop = threading.Event()
        self._thread: threading.Thread | None = None

    def start(self) -> None:
        """Start the thread; calling it again while it runs does nothing."""
        if self._thread is not None and self._thread.is_alive():
            return
        self._stop.clear()
        self._thread = threading.Thread(target=self._loop, name="scheduler", daemon=True)
        self._thread.start()

    def stop(self, timeout: float = 5) -> None:
        self._stop.set()
        if self._thread is not None:
            self._thread.join(timeout)

    def _loop(self) -> None:
        logger.info("Scheduler started")
        while not self._stop.is_set():
            try:
                self._tick()
            except Exception:
                logger.exception("Scheduler tick failed")
            finally:
                close_old_connections()
            self._stop.wait(self._interval)
        logger.info("Scheduler stopped")


runner = Runner()