"""Celery tasks for OCR processing of uploaded screenshots."""
import asyncio
import logging
import json
from uuid import UUID

from app.workers.celery_app import celery_app

logger = logging.getLogger(__name__)


def _run_async(coro):
    """Run an async coroutine from synchronous Celery task context."""
    loop = asyncio.new_event_loop()
    try:
        return loop.run_until_complete(coro)
    finally:
        loop.close()


@celery_app.task(name="app.workers.ocr_tasks.process_image_ocr", bind=True, max_retries=3)
def process_image_ocr(self, image_id: str):
    """Process a single image: classify page, extract fields, save to DB."""
    _run_async(process_image_ocr_async(image_id))


async def process_images_ocr_batch_async(image_ids: list[str], max_concurrency: int) -> None:
    """Process many images with bounded OCR concurrency."""
    if not image_ids:
        return
    # De-duplicate in-memory to prevent repeated processing of same image id
    # in a single batch submission.
    image_ids = list(dict.fromkeys(image_ids))
    concurrency = max(1, max_concurrency)
    semaphore = asyncio.Semaphore(concurrency)

    async def _run_one(image_id: str) -> None:
        async with semaphore:
            try:
                await process_image_ocr_async(image_id)
            except Exception:
                # Keep batch processing alive even if one image fails.
                logger.exception("Image %s OCR failed in batch", image_id)

    await asyncio.gather(*[_run_one(image_id) for image_id in image_ids])


async def process_image_ocr_async(image_id_str: str):
    from app.core.database import async_session_factory
    from sqlalchemy import delete
    from app.models.evidence_image import EvidenceImage, OcrStatus
    from app.models.ocr_block import OcrBlock
    from app.models.transaction import TransactionRecord
    from app.services.ocr_service import classify_page, extract_transaction_fields
    from app.services.parser_service import parse_extracted_fields

    image_id = UUID(image_id_str)
    async with async_session_factory() as db:
        image = await db.get(EvidenceImage, image_id)
        if not image:
            logger.error("Image %s not found", image_id)
            return

        image.ocr_status = OcrStatus.processing
        await db.flush()
        # Re-run OCR for this image should replace old OCR blocks/records.
        await db.execute(delete(OcrBlock).where(OcrBlock.image_id == image.id))
        await db.execute(delete(TransactionRecord).where(TransactionRecord.evidence_image_id == image.id))

        try:
            source_app, page_type = await classify_page(image.file_path)
            image.source_app = source_app
            image.page_type = page_type

            raw_fields, raw_ocr_text = await extract_transaction_fields(image.file_path, source_app, page_type)

            is_empty_extract = raw_fields is None or raw_fields == {} or raw_fields == []

            # save raw OCR block (direct model output for debugging)
            raw_block_content = (raw_ocr_text or "").strip()
            if raw_block_content:
                block = OcrBlock(
                    image_id=image.id,
                    content=raw_block_content,
                    bbox={},
                    seq_order=0,
                    confidence=raw_fields.get("confidence", 0.5) if isinstance(raw_fields, dict) else 0.5,
                )
                db.add(block)
            elif not is_empty_extract:
                block = OcrBlock(
                    image_id=image.id,
                    content=json.dumps(raw_fields, ensure_ascii=False),
                    bbox={},
                    seq_order=0,
                    confidence=raw_fields.get("confidence", 0.5) if isinstance(raw_fields, dict) else 0.5,
                )
                db.add(block)

            # parse into transaction records
            records = parse_extracted_fields(raw_fields, image.case_id, image.id, source_app)
            for r in records:
                db.add(r)

            image.ocr_status = OcrStatus.done
            await db.commit()
            logger.info("Image %s processed: %d transactions", image_id, len(records))

        except Exception as e:
            image.ocr_status = OcrStatus.failed
            await db.commit()
            logger.error("Image %s OCR failed: %s", image_id, e)
            raise