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

from datetime import datetime, timedelta, timezone
from sqlalchemy.orm import Session

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

def sweep_trash(db: Session) -> None:
    """Permanently delete documents that have been in the trash past the retention period."""
    cutoff = datetime.now(timezone.utc) - timedelta(days=settings.TRASH_RETENTION_DAYS)
    cutoff_iso = cutoff.isoformat()
    
    docs_to_delete = db.query(Document).filter(
        Document.in_trash == True,
        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 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(timezone.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()