import logging
from datetime import datetime
from threading import Event, Thread

import pytz

from core.data_store import DATA_STORE


class CleanupTimer:
    """Provides a timed cleanup of the spot list."""

    def __init__(self):
        """Constructor"""

        self._cleanup_interval = None
        self.last_cleanup_time = datetime.min.replace(tzinfo=pytz.UTC)
        self.status = "Starting"
        self._thread = None
        self._stop_event = Event()

    def setup(self, cleanup_interval):
        self._cleanup_interval = cleanup_interval

    def start(self):
        """Start the cleanup timer"""

        self._thread = Thread(target=self._run, daemon=True)
        self._thread.start()

    def stop(self):
        """Stop any threads and prepare for application shutdown"""

        self._stop_event.set()

    def _run(self):
        while not self._stop_event.wait(timeout=self._cleanup_interval):
            self._cleanup()

    def _cleanup(self):
        """Perform cleanup and reschedule next timer"""

        try:
            for i in list(DATA_STORE.spots.keys()):
                try:
                    spot = DATA_STORE.spots[i]
                    if spot.expired():
                        DATA_STORE.spots.delete(i)
                except KeyError:
                    # Must have already been deleted, OK with that
                    pass
            for i in list(DATA_STORE.alerts.keys()):
                try:
                    alert = DATA_STORE.alerts[i]
                    if alert.expired():
                        DATA_STORE.alerts.delete(i)
                except KeyError:
                    # Must have already been deleted, OK with that
                    pass

            self.status = "OK"
            self.last_cleanup_time = datetime.now(pytz.UTC)

        except Exception:
            self.status = "Error"
            logging.exception("Exception in Cleanup thread")
            self._stop_event.wait(timeout=1)


# Global object
CLEANUP_TIMER = CleanupTimer()