"""Background job scheduler for album polling."""

from __future__ import annotations

import logging

from apscheduler.schedulers.asyncio import AsyncIOScheduler
from apscheduler.triggers.interval import IntervalTrigger
from sqlmodel import select
from sqlmodel.ext.asyncio.session import AsyncSession

from ..database.engine import get_engine
from ..database.models import AlbumTracker
from .watcher import check_tracker

_LOGGER = logging.getLogger(__name__)

_scheduler: AsyncIOScheduler | None = None


def get_scheduler() -> AsyncIOScheduler:
    """Get the global scheduler instance."""
    global _scheduler
    if _scheduler is None:
        _scheduler = AsyncIOScheduler()
    return _scheduler


async def start_scheduler() -> None:
    """Start the scheduler and load all enabled trackers."""
    scheduler = get_scheduler()

    engine = get_engine()
    async with AsyncSession(engine) as session:
        result = await session.exec(
            select(AlbumTracker).where(AlbumTracker.enabled == True)  # noqa: E712
        )
        trackers = result.all()

    for tracker in trackers:
        _add_tracker_job(scheduler, tracker.id, tracker.scan_interval)

    scheduler.start()
    _LOGGER.info("Scheduler started with %d tracker jobs", len(trackers))


async def stop_scheduler() -> None:
    """Stop the scheduler."""
    scheduler = get_scheduler()
    if scheduler.running:
        scheduler.shutdown(wait=False)
        _LOGGER.info("Scheduler stopped")


def add_tracker_job(tracker_id: int, scan_interval: int) -> None:
    """Add or update a scheduler job for a tracker."""
    scheduler = get_scheduler()
    _add_tracker_job(scheduler, tracker_id, scan_interval)


def remove_tracker_job(tracker_id: int) -> None:
    """Remove a scheduler job for a tracker."""
    scheduler = get_scheduler()
    job_id = f"tracker_{tracker_id}"
    if scheduler.get_job(job_id):
        scheduler.remove_job(job_id)
        _LOGGER.debug("Removed scheduler job for tracker %d", tracker_id)


def _add_tracker_job(
    scheduler: AsyncIOScheduler, tracker_id: int, scan_interval: int
) -> None:
    """Add or replace a scheduler job."""
    job_id = f"tracker_{tracker_id}"

    # Remove existing job if present
    if scheduler.get_job(job_id):
        scheduler.remove_job(job_id)

    scheduler.add_job(
        _run_tracker_check,
        trigger=IntervalTrigger(seconds=scan_interval),
        id=job_id,
        args=[tracker_id],
        replace_existing=True,
        max_instances=1,
    )
    _LOGGER.debug(
        "Scheduled tracker %d every %d seconds", tracker_id, scan_interval
    )


async def _run_tracker_check(tracker_id: int) -> None:
    """Run a single tracker check (called by scheduler)."""
    try:
        result = await check_tracker(tracker_id)
        _LOGGER.debug("Tracker %d check result: %s", tracker_id, result)
    except Exception:
        _LOGGER.exception("Error checking tracker %d", tracker_id)