"""Async OCR processing task using background tasks.

In production this would use Redis Queue (RQ) or Celery.
For now, we use FastAPI BackgroundTasks to trigger async processing.
"""

from __future__ import annotations

import logging
import uuid

from sqlalchemy.ext.asyncio import AsyncSession

from app.database import async_session_factory
from app.services.ocr_service import process_ocr

logger = logging.getLogger(__name__)


async def run_ocr_processing(result_id: uuid.UUID) -> None:
    """Background task: process OCR result asynchronously.

    Creates its own DB session (independent of the request session)
    so the HTTP response can return immediately.
    """
    async with async_session_factory() as session:
        try:
            await process_ocr(session, result_id)
            await session.commit()
            logger.info("OCR processing completed for result %s", result_id)
        except Exception as exc:
            await session.rollback()
            logger.error("OCR background task failed for %s: %s", result_id, exc)
            raise
        finally:
            await session.close()