"""Background task: auto-mark overdue pending reservations as no_show."""
import asyncio
import logging
from datetime import datetime, timezone, timedelta

logger = logging.getLogger(__name__)

# Grace period after reserved_for before a pending reservation becomes no_show
NO_SHOW_GRACE_MINUTES = 30

# How often the checker runs
CHECK_INTERVAL_SECONDS = 300  # 5 minutes


async def _run_no_show_checker():
    # Import here to avoid circular imports at module load time
    from database import SessionLocal
    from models.reservation import Reservation

    while True:
        await asyncio.sleep(CHECK_INTERVAL_SECONDS)
        try:
            db = SessionLocal()
            try:
                cutoff = datetime.now(timezone.utc) - timedelta(minutes=NO_SHOW_GRACE_MINUTES)
                overdue = (
                    db.query(Reservation)
                    .filter(
                        Reservation.status == "pending",
                        Reservation.reserved_for < cutoff,
                    )
                    .all()
                )
                if overdue:
                    for r in overdue:
                        r.status = "no_show"
                        r.updated_at = datetime.now(timezone.utc)
                    db.commit()
                    logger.info("no_show_checker: marked %d reservation(s) as no_show", len(overdue))
            finally:
                db.close()
        except Exception:
            logger.exception("no_show_checker: unexpected error")


async def start_reservation_tasks() -> asyncio.Task:
    task = asyncio.create_task(_run_no_show_checker())
    return task