"""Async OCR job endpoints."""
import asyncio
import logging
from typing import Optional, Union

from fastapi import APIRouter, BackgroundTasks, File, Form, HTTPException, UploadFile

from app.models import JobResponse, JobSubmitRequest, ManualJobResponse
from app.services import job_queue, ocr_service

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/jobs", tags=["jobs"])

# Maximum file size for async processing (200MB)
MAX_ASYNC_SIZE = 200 * 1024 * 1024


@router.post("", response_model=JobResponse)
async def submit_job(
    background_tasks: BackgroundTasks,
    file: UploadFile = File(..., description="Image file to process"),
    callback_url: Optional[str] = Form(None, description="URL to call when job completes"),
) -> JobResponse:
    """
    Submit an async OCR job for large files.

    Use this endpoint for files larger than 10MB or when you don't want to wait
    for processing to complete. Poll GET /jobs/{job_id} for status.

    - **file**: Image file (max 200MB)
    - **callback_url**: Optional webhook URL to receive job completion notification
    """
    # Validate file presence
    if not file.filename:
        raise HTTPException(status_code=400, detail="No file provided")

    # Read file content
    content = await file.read()
    file_size = len(content)

    # Validate file size
    if file_size > MAX_ASYNC_SIZE:
        raise HTTPException(
            status_code=413,
            detail=f"File too large. Max: {MAX_ASYNC_SIZE // (1024*1024)}MB.",
        )

    if file_size == 0:
        raise HTTPException(status_code=400, detail="Empty file provided")

    logger.info(
        f"Submitting async job: {file.filename}, "
        f"size: {file_size} bytes, "
        f"content_type: {file.content_type}"
    )

    # Submit job to queue
    job_id = await job_queue.submit_job(
        file_bytes=content,
        content_type=file.content_type or "application/octet-stream",
        callback_url=callback_url,
    )

    # Schedule background processing
    background_tasks.add_task(process_job, job_id)

    # Return initial status
    return JobResponse(
        jobId=job_id,
        status="pending",
        progress=0,
    )


@router.get("/{job_id}", response_model=Union[JobResponse, ManualJobResponse])
async def get_job_status(job_id: str) -> Union[JobResponse, ManualJobResponse]:
    """
    Get the status of an async OCR job.

    Poll this endpoint to check job progress and retrieve results.
    Works for both regular OCR jobs and manual extraction jobs.

    Returns:
    - **pending**: Job is queued
    - **processing**: Job is being processed (includes progress %)
    - **completed**: Job finished successfully (includes result)
    - **failed**: Job failed (includes error message)
    """
    # Try regular job first
    result = await job_queue.get_job_status(job_id)
    if result is not None:
        return result

    # Try manual job
    manual_result = await job_queue.get_manual_job_status(job_id)
    if manual_result is not None:
        return manual_result

    raise HTTPException(
        status_code=404,
        detail=f"Job {job_id} not found. Jobs expire after 1-2 hours.",
    )


async def process_job(job_id: str) -> None:
    """Background task to process an OCR job."""
    logger.info(f"Starting job {job_id}")

    try:
        # Update status to processing
        await job_queue.update_job_progress(job_id, 10)

        # Get job data
        file_bytes = await job_queue.get_job_data(job_id)
        if not file_bytes:
            await job_queue.fail_job(job_id, "Job data not found")
            return

        await job_queue.update_job_progress(job_id, 30)

        # Get metadata for content type
        status = await job_queue.get_job_status(job_id)
        if not status:
            return

        # Perform OCR in thread pool (CPU-bound operation)
        await job_queue.update_job_progress(job_id, 50)

        loop = asyncio.get_event_loop()
        result = await loop.run_in_executor(
            None,
            lambda: ocr_service.extract(
                file_bytes=file_bytes,
                preprocess=True,
            ),
        )

        await job_queue.update_job_progress(job_id, 90)

        if result.success:
            await job_queue.complete_job(job_id, result)
        else:
            await job_queue.fail_job(job_id, "OCR extraction failed")

    except Exception as e:
        logger.error(f"Job {job_id} failed: {e}", exc_info=True)
        await job_queue.fail_job(job_id, str(e))