import fcntl
import logging
import os
import threading

from collectors import InventoryCollectorOrchestrator
from config import AppConfig

LOGGER = logging.getLogger(__name__)


class CollectionScheduler:
    def __init__(self, config: AppConfig, orchestrator: InventoryCollectorOrchestrator):
        self.config = config
        self.orchestrator = orchestrator
        self._stop_event = threading.Event()
        self._thread: threading.Thread | None = None
        self._leader_file = None

    def start(self) -> bool:
        if not self.config.scheduler_enabled:
            LOGGER.info("Scheduler disabled via config")
            return False

        leader_file = open("/tmp/inventory-scheduler.lock", "w", encoding="utf-8")
        try:
            fcntl.flock(leader_file.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
        except OSError:
            leader_file.close()
            LOGGER.info("Another worker owns scheduler lock")
            return False

        self._leader_file = leader_file

        self._thread = threading.Thread(target=self._run_loop, name="inventory-scheduler", daemon=True)
        self._thread.start()
        LOGGER.info("Scheduler started with %s second interval", self.config.poll_interval_seconds)
        return True

    def _run_loop(self) -> None:
        while not self._stop_event.is_set():
            self.orchestrator.collect_once()
            self._stop_event.wait(self.config.poll_interval_seconds)

    def shutdown(self) -> None:
        self._stop_event.set()
        if self._thread and self._thread.is_alive():
            self._thread.join(timeout=1.0)
        if self._leader_file:
            fcntl.flock(self._leader_file.fileno(), fcntl.LOCK_UN)
            self._leader_file.close()
            self._leader_file = None


def should_autostart_scheduler() -> bool:
    # Do not auto-start on Flask's reloader child process.
    return os.getenv("WERKZEUG_RUN_MAIN", "true") != "false"