"""Periodic cleanup of TTL data: expired drafts, old container snapshots and access attempts."""

import asyncio
import logging
from datetime import datetime, timedelta
from typing import Any, cast

from sqlalchemy import CursorResult, Delete, delete
from sqlalchemy.ext.asyncio import AsyncSession

from app.db.models import AccessAttempt, ContainerSnapshot, Draft, utcnow
from app.db.session import SessionMaker

log = logging.getLogger(__name__)

SNAPSHOT_TTL = timedelta(days=1)
ATTEMPT_TTL = timedelta(days=1)


async def _delete(session: AsyncSession, stmt: Delete) -> int:
    # DML executes into a CursorResult; the generic annotation of execute() just doesn't say so
    return cast(CursorResult[Any], await session.execute(stmt)).rowcount


async def cleanup_expired(sessions: SessionMaker, now: datetime) -> dict[str, int]:
    async with sessions.begin() as session:
        return {
            "drafts": await _delete(session, delete(Draft).where(Draft.expires_at < now)),
            "snapshots": await _delete(
                session, delete(ContainerSnapshot).where(ContainerSnapshot.at < now - SNAPSHOT_TTL)
            ),
            "access_attempts": await _delete(
                session, delete(AccessAttempt).where(AccessAttempt.at < now - ATTEMPT_TTL)
            ),
        }


async def cleanup_loop(sessions: SessionMaker, interval: float = 3600.0) -> None:
    while True:
        try:
            removed = await cleanup_expired(sessions, utcnow())
            if any(removed.values()):
                log.info("cleanup: %s", removed)
        except Exception:  # a failed cleanup must not kill the bot; retry next round
            log.exception("cleanup failed")
        await asyncio.sleep(interval)