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

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

from app.models import JobResponse, JobSubmitRequest
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=JobResponse)
async def get_job_status(job_id: str) -> JobResponse:
    """
    Get the status of an async OCR job.

    Poll this endpoint to check job progress and retrieve results.

    Returns:
    - **pending**: Job is queued
    - **processing**: Job is being processed (includes progress %)
    - **completed**: Job finished successfully (includes result)
    - **failed**: Job failed (includes error message)
    """
    result = await job_queue.get_job_status(job_id)

    if result is None:
        raise HTTPException(
            status_code=404,
            detail=f"Job {job_id} not found. Jobs expire after 1 hour.",
        )

    return result


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))