"""
Tool_OCR - OCR Router
File upload, OCR processing, and status endpoints
"""

import logging
from typing import List
from pathlib import Path

from fastapi import APIRouter, Depends, HTTPException, status, UploadFile, File, BackgroundTasks
from sqlalchemy.orm import Session

from app.core.deps import get_db, get_current_active_user
from app.models.user import User
from app.models.ocr import OCRBatch, OCRFile, OCRResult, BatchStatus, FileStatus
from app.schemas.ocr import (
    OCRBatchResponse,
    BatchStatusResponse,
    FileStatusResponse,
    OCRResultDetailResponse,
    UploadBatchResponse,
    ProcessRequest,
    ProcessResponse,
)
from app.services.file_manager import FileManager, FileManagementError
from app.services.ocr_service import OCRService
from app.services.background_tasks import process_batch_files_with_retry


logger = logging.getLogger(__name__)

router = APIRouter(prefix="/api/v1", tags=["OCR"])

# Initialize services
file_manager = FileManager()
ocr_service = OCRService()


@router.post("/upload", response_model=UploadBatchResponse, summary="Upload files for OCR")
async def upload_files(
    files: List[UploadFile] = File(..., description="Files to upload (PNG, JPG, PDF)"),
    batch_name: str = None,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_active_user)
):
    """
    Upload files for OCR processing

    Creates a new batch and uploads files to it

    - **files**: List of files to upload (PNG, JPG, JPEG, PDF)
    - **batch_name**: Optional name for the batch
    """
    if not files:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="No files provided"
        )

    try:
        # Create batch
        batch = file_manager.create_batch(db, current_user.id, batch_name)

        # Upload files
        uploaded_files = file_manager.add_files_to_batch(db, batch.id, files)

        logger.info(f"Uploaded {len(uploaded_files)} files to batch {batch.id} for user {current_user.id}")

        # Refresh batch to get updated counts
        db.refresh(batch)

        # Return response matching frontend expectations
        return {
            "batch_id": batch.id,
            "files": uploaded_files
        }

    except FileManagementError as e:
        logger.error(f"File upload error: {e}")
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=str(e)
        )
    except Exception as e:
        logger.error(f"Unexpected error during upload: {e}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Failed to upload files"
        )


# NOTE: process_batch_files function moved to app.services.background_tasks
# Now using process_batch_files_with_retry with retry logic

@router.post("/ocr/process", response_model=ProcessResponse, summary="Trigger OCR processing")
async def process_ocr(
    request: ProcessRequest,
    background_tasks: BackgroundTasks,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_active_user)
):
    """
    Trigger OCR processing for a batch

    Starts background processing of all files in the batch

    - **batch_id**: Batch ID to process
    - **lang**: Language code (ch, en, japan, korean)
    - **detect_layout**: Enable layout detection
    """
    # Verify batch ownership
    batch = db.query(OCRBatch).filter(
        OCRBatch.id == request.batch_id,
        OCRBatch.user_id == current_user.id
    ).first()

    if not batch:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Batch not found"
        )

    if batch.status != BatchStatus.PENDING:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Batch is already {batch.status.value}"
        )

    # Start background processing with retry logic
    background_tasks.add_task(
        process_batch_files_with_retry,
        batch_id=batch.id,
        lang=request.lang,
        detect_layout=request.detect_layout,
        db=SessionLocal()  # Create new session for background task
    )

    logger.info(f"Started OCR processing for batch {batch.id}")

    return {
        "message": "OCR processing started",
        "batch_id": batch.id,
        "total_files": batch.total_files,
        "status": "processing"
    }


@router.get("/batch/{batch_id}/status", response_model=BatchStatusResponse, summary="Get batch status")
async def get_batch_status(
    batch_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_active_user)
):
    """
    Get batch processing status

    Returns batch information and all files in the batch

    - **batch_id**: Batch ID
    """
    # Verify batch ownership
    batch = db.query(OCRBatch).filter(
        OCRBatch.id == batch_id,
        OCRBatch.user_id == current_user.id
    ).first()

    if not batch:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Batch not found"
        )

    # Get all files in batch
    files = db.query(OCRFile).filter(OCRFile.batch_id == batch_id).all()

    return {
        "batch": batch,
        "files": files
    }


@router.get("/ocr/result/{file_id}", response_model=OCRResultDetailResponse, summary="Get OCR result")
async def get_ocr_result(
    file_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_active_user)
):
    """
    Get OCR result for a file

    Returns flattened file and OCR result information for frontend preview

    - **file_id**: File ID
    """
    # Get file
    ocr_file = db.query(OCRFile).join(OCRBatch).filter(
        OCRFile.id == file_id,
        OCRBatch.user_id == current_user.id
    ).first()

    if not ocr_file:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="File not found"
        )

    # Get result if exists
    result = db.query(OCRResult).filter(OCRResult.file_id == file_id).first()

    # Read markdown content if result exists
    markdown_content = None
    if result and result.markdown_path:
        markdown_file = Path(result.markdown_path)
        if markdown_file.exists():
            try:
                markdown_content = markdown_file.read_text(encoding='utf-8')
            except Exception as e:
                logger.warning(f"Failed to read markdown file {result.markdown_path}: {e}")

    # Build JSON data from result if available
    json_data = None
    if result:
        json_data = {
            "total_text_regions": result.total_text_regions,
            "average_confidence": result.average_confidence,
            "detected_language": result.detected_language,
            "layout_data": result.layout_data,
            "images_metadata": result.images_metadata,
        }

    # Return flattened structure matching frontend expectations
    return {
        "file_id": ocr_file.id,
        "filename": ocr_file.filename,
        "status": ocr_file.status.value,
        "markdown_content": markdown_content,
        "json_data": json_data,
        "confidence": result.average_confidence if result else None,
        "processing_time": ocr_file.processing_time,
    }


# Import SessionLocal for background tasks
from app.core.database import SessionLocal