"""
Background job for cleaning up expired sessions.

This service runs periodically to remove old session records from the database.
"""
import logging
from datetime import datetime, timezone

from app.core.database import SessionLocal
from app.crud.session import session as session_crud

logger = logging.getLogger(__name__)


async def cleanup_expired_sessions(keep_days: int = 30) -> int:
    """
    Clean up expired and inactive sessions.

    This removes sessions that are:
    - Inactive (is_active=False) AND
    - Expired (expires_at < now) AND
    - Older than keep_days

    Args:
        keep_days: Keep inactive sessions for this many days for audit purposes

    Returns:
        Number of sessions deleted
    """
    logger.info("Starting session cleanup job...")

    async with SessionLocal() as db:
        try:
            # Use CRUD method to cleanup
            count = await session_crud.cleanup_expired(db, keep_days=keep_days)

            logger.info(f"Session cleanup complete: {count} sessions deleted")

            return count

        except Exception as e:
            logger.error(f"Error during session cleanup: {str(e)}", exc_info=True)
            return 0


async def get_session_statistics() -> dict:
    """
    Get statistics about current sessions.

    Returns:
        Dictionary with session stats
    """
    async with SessionLocal() as db:
        try:
            from app.models.user_session import UserSession
            from sqlalchemy import select, func

            total_result = await db.execute(select(func.count(UserSession.id)))
            total_sessions = total_result.scalar_one()

            active_result = await db.execute(
                select(func.count(UserSession.id)).where(UserSession.is_active == True)
            )
            active_sessions = active_result.scalar_one()

            expired_result = await db.execute(
                select(func.count(UserSession.id)).where(
                    UserSession.expires_at < datetime.now(timezone.utc)
                )
            )
            expired_sessions = expired_result.scalar_one()

            stats = {
                "total": total_sessions,
                "active": active_sessions,
                "inactive": total_sessions - active_sessions,
                "expired": expired_sessions,
            }

            logger.info(f"Session statistics: {stats}")

            return stats

        except Exception as e:
            logger.error(f"Error getting session statistics: {str(e)}", exc_info=True)
            return {}