"""Background tasks for sweeping trash and old versions."""

from datetime import UTC, datetime, timedelta

from sqlalchemy.orm import Session

from app.config import settings
from app.models.annotation_state import AnnotationState
from app.models.document import Document
from app.models.version import Version
from app.services.assets import delete_asset_directory
from app.services.storage import delete_pdf_file
from app.services.thumbnails import delete_thumbnail


def sweep_trash(db: Session) -> None:
    """Permanently delete documents that have been in the trash past the retention period."""
    cutoff = datetime.now(UTC) - timedelta(days=settings.TRASH_RETENTION_DAYS)
    cutoff_iso = cutoff.isoformat()

    docs_to_delete = (
        db.query(Document)
        .filter(Document.deleted_at.is_not(None), Document.deleted_at <= cutoff_iso)
        .all()
    )

    for doc in docs_to_delete:
        # Delete files from disk
        delete_pdf_file(doc.id)
        delete_thumbnail(doc.id)
        delete_asset_directory(doc.id)

        # Delete DB associations
        db.query(AnnotationState).filter(AnnotationState.document_id == doc.id).delete()
        db.query(Version).filter(Version.document_id == doc.id).delete()

        # Delete document record
        db.delete(doc)

    db.commit()


def prune_auto_versions(db: Session) -> None:
    """Delete automatic versions older than the retention period."""
    cutoff = datetime.now(UTC) - timedelta(days=settings.AUTO_VERSION_RETENTION_DAYS)
    cutoff_iso = cutoff.isoformat()

    db.query(Version).filter(Version.kind == "auto", Version.created_at <= cutoff_iso).delete()

    db.commit()