"""Scheduled job for periodic MITRE ATT&CK synchronisation.

Uses APScheduler's ``BackgroundScheduler`` to run :func:`sync_mitre` every
24 hours.  The job manages its own database session (created on entry,
closed in ``finally``) so it is fully independent from FastAPI's
request-scoped sessions.
"""

import logging

from apscheduler.schedulers.background import BackgroundScheduler

from app.database import SessionLocal
from app.services.mitre_sync_service import sync_mitre

logger = logging.getLogger(__name__)

# ---------------------------------------------------------------------------
# Module-level scheduler instance
# ---------------------------------------------------------------------------

scheduler = BackgroundScheduler()


def _run_mitre_sync() -> None:
    """Execute a MITRE sync inside its own DB session."""
    logger.info("Scheduled MITRE sync job starting...")
    db = SessionLocal()
    try:
        summary = sync_mitre(db)
        logger.info("Scheduled MITRE sync job finished — %s", summary)
    except Exception:
        logger.exception("Scheduled MITRE sync job failed")
    finally:
        db.close()


def start_scheduler() -> None:
    """Register the MITRE sync job and start the background scheduler.

    The job runs every **24 hours**.  It does **not** fire immediately on
    startup — the first execution happens 24 h after the application boots.
    """
    scheduler.add_job(
        _run_mitre_sync,
        trigger="interval",
        hours=24,
        id="mitre_sync",
        name="MITRE ATT&CK sync (every 24h)",
        replace_existing=True,
    )
    scheduler.start()
    logger.info("MITRE sync scheduler started (interval=24h)")