"""Celery Beat-triggered housekeeping. Currently just the data-retention
purge (DATA_RETENTION_DAYS) - only SourceDocument rows are ever deleted
here; see SourceDocumentRepository.delete_older_than for why that's the
only safe target in the current FK graph.
"""

from __future__ import annotations

from datetime import UTC, datetime, timedelta

from structlog.contextvars import bound_contextvars

from app.core.config import get_settings
from app.core.logging import get_logger
from app.db.session import get_sessionmaker
from app.repositories.source_repository import SourceDocumentRepository
from app.tasks.base import run_async_task
from app.tasks.celery_app import celery_app

logger = get_logger(__name__)


@celery_app.task(bind=True, name="app.tasks.maintenance.purge_expired_data")
def purge_expired_data(self) -> None:
    with bound_contextvars(task_id=self.request.id):
        run_async_task(_purge_expired_data_async())


async def _purge_expired_data_async() -> None:
    settings = get_settings()
    cutoff = datetime.now(UTC) - timedelta(days=settings.data_retention_days)

    session_factory = get_sessionmaker()
    async with session_factory() as db:
        deleted = await SourceDocumentRepository(db).delete_older_than(cutoff)
        await db.commit()

    logger.info(
        "data_retention_purge_completed",
        deleted_source_documents=deleted,
        retention_days=settings.data_retention_days,
        cutoff=cutoff.isoformat(),
    )