"""
Tool_OCR - Task Management Router
Handles OCR task operations with user isolation
"""

import logging
from typing import Optional
from pathlib import Path
import shutil
import hashlib

from fastapi import APIRouter, Depends, HTTPException, status, Query, UploadFile, File
from fastapi.responses import FileResponse
from sqlalchemy.orm import Session

from app.core.deps import get_db, get_current_user
from app.core.config import settings
from app.models.user import User
from app.models.task import TaskStatus, TaskFile
from app.schemas.task import (
    TaskCreate,
    TaskUpdate,
    TaskResponse,
    TaskDetailResponse,
    TaskListResponse,
    TaskStatsResponse,
    TaskStatusEnum,
    UploadResponse,
)
from app.services.task_service import task_service
from app.services.file_access_service import file_access_service

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/api/v2/tasks", tags=["Tasks"])


@router.post("/", response_model=TaskResponse, status_code=status.HTTP_201_CREATED)
async def create_task(
    task_data: TaskCreate,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Create a new OCR task

    - **filename**: Original filename (optional)
    - **file_type**: File MIME type (optional)
    """
    try:
        task = task_service.create_task(
            db=db,
            user_id=current_user.id,
            filename=task_data.filename,
            file_type=task_data.file_type
        )

        logger.info(f"Created task {task.task_id} for user {current_user.email}")
        return task

    except Exception as e:
        logger.exception(f"Failed to create task for user {current_user.id}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to create task: {str(e)}"
        )


@router.get("/", response_model=TaskListResponse)
async def list_tasks(
    status_filter: Optional[TaskStatusEnum] = Query(None, alias="status"),
    filename_search: Optional[str] = Query(None, alias="filename"),
    date_from: Optional[str] = Query(None, alias="date_from"),
    date_to: Optional[str] = Query(None, alias="date_to"),
    page: int = Query(1, ge=1),
    page_size: int = Query(50, ge=1, le=100),
    order_by: str = Query("created_at"),
    order_desc: bool = Query(True),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    List user's tasks with pagination and filtering

    - **status**: Filter by task status (optional)
    - **filename**: Search by filename (partial match, optional)
    - **date_from**: Filter tasks from this date (YYYY-MM-DD, optional)
    - **date_to**: Filter tasks until this date (YYYY-MM-DD, optional)
    - **page**: Page number (starts from 1)
    - **page_size**: Number of tasks per page (max 100)
    - **order_by**: Sort field (created_at, updated_at, completed_at)
    - **order_desc**: Sort descending (default: true)
    """
    try:
        # Convert enum to model enum if provided
        status_enum = TaskStatus[status_filter.value.upper()] if status_filter else None

        # Parse date strings
        from datetime import datetime
        date_from_dt = datetime.fromisoformat(date_from) if date_from else None
        date_to_dt = datetime.fromisoformat(date_to) if date_to else None

        # Calculate offset
        skip = (page - 1) * page_size

        # Get tasks
        tasks, total = task_service.get_user_tasks(
            db=db,
            user_id=current_user.id,
            status=status_enum,
            filename_search=filename_search,
            date_from=date_from_dt,
            date_to=date_to_dt,
            skip=skip,
            limit=page_size,
            order_by=order_by,
            order_desc=order_desc
        )

        # Calculate pagination
        has_more = (skip + len(tasks)) < total

        return {
            "tasks": tasks,
            "total": total,
            "page": page,
            "page_size": page_size,
            "has_more": has_more
        }

    except Exception as e:
        logger.exception(f"Failed to list tasks for user {current_user.id}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to list tasks: {str(e)}"
        )


@router.get("/stats", response_model=TaskStatsResponse)
async def get_task_stats(
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Get task statistics for current user

    Returns counts by status
    """
    try:
        stats = task_service.get_user_stats(db=db, user_id=current_user.id)
        return stats

    except Exception as e:
        logger.exception(f"Failed to get stats for user {current_user.id}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to get statistics: {str(e)}"
        )


@router.get("/{task_id}", response_model=TaskDetailResponse)
async def get_task(
    task_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Get task details by ID

    - **task_id**: Task UUID
    """
    task = task_service.get_task_by_id(
        db=db,
        task_id=task_id,
        user_id=current_user.id
    )

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

    return task


@router.patch("/{task_id}", response_model=TaskResponse)
async def update_task(
    task_id: str,
    task_update: TaskUpdate,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Update task status and results

    - **task_id**: Task UUID
    - **status**: New task status (optional)
    - **error_message**: Error message if failed (optional)
    - **processing_time_ms**: Processing time in milliseconds (optional)
    - **result_json_path**: Path to JSON result (optional)
    - **result_markdown_path**: Path to Markdown result (optional)
    - **result_pdf_path**: Path to searchable PDF (optional)
    """
    try:
        # Update status if provided
        if task_update.status:
            status_enum = TaskStatus[task_update.status.value.upper()]
            task = task_service.update_task_status(
                db=db,
                task_id=task_id,
                user_id=current_user.id,
                status=status_enum,
                error_message=task_update.error_message,
                processing_time_ms=task_update.processing_time_ms
            )

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

        # Update result paths if provided
        if any([
            task_update.result_json_path,
            task_update.result_markdown_path,
            task_update.result_pdf_path
        ]):
            task = task_service.update_task_results(
                db=db,
                task_id=task_id,
                user_id=current_user.id,
                result_json_path=task_update.result_json_path,
                result_markdown_path=task_update.result_markdown_path,
                result_pdf_path=task_update.result_pdf_path
            )

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

        return task

    except HTTPException:
        raise
    except Exception as e:
        logger.exception(f"Failed to update task {task_id}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to update task: {str(e)}"
        )


@router.delete("/{task_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_task(
    task_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Delete a task

    - **task_id**: Task UUID
    """
    success = task_service.delete_task(
        db=db,
        task_id=task_id,
        user_id=current_user.id
    )

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

    logger.info(f"Deleted task {task_id} for user {current_user.email}")
    return None


@router.get("/{task_id}/download/json", summary="Download JSON result")
async def download_json(
    task_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Download task result as JSON file

    - **task_id**: Task UUID
    """
    # Get task
    task = task_service.get_task_by_id(
        db=db,
        task_id=task_id,
        user_id=current_user.id
    )

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

    # Validate file access
    is_valid, error_msg = file_access_service.validate_file_access(
        db=db,
        user_id=current_user.id,
        task_id=task_id,
        file_path=task.result_json_path
    )

    if not is_valid:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=error_msg
        )

    # Return file
    filename = f"{task.filename or task_id}_result.json"
    return FileResponse(
        path=task.result_json_path,
        filename=filename,
        media_type="application/json"
    )


@router.get("/{task_id}/download/markdown", summary="Download Markdown result")
async def download_markdown(
    task_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Download task result as Markdown file

    - **task_id**: Task UUID
    """
    # Get task
    task = task_service.get_task_by_id(
        db=db,
        task_id=task_id,
        user_id=current_user.id
    )

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

    # Validate file access
    is_valid, error_msg = file_access_service.validate_file_access(
        db=db,
        user_id=current_user.id,
        task_id=task_id,
        file_path=task.result_markdown_path
    )

    if not is_valid:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=error_msg
        )

    # Return file
    filename = f"{task.filename or task_id}_result.md"
    return FileResponse(
        path=task.result_markdown_path,
        filename=filename,
        media_type="text/markdown"
    )


@router.get("/{task_id}/download/pdf", summary="Download PDF result")
async def download_pdf(
    task_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Download task result as searchable PDF file

    - **task_id**: Task UUID
    """
    # Get task
    task = task_service.get_task_by_id(
        db=db,
        task_id=task_id,
        user_id=current_user.id
    )

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

    # Validate file access
    is_valid, error_msg = file_access_service.validate_file_access(
        db=db,
        user_id=current_user.id,
        task_id=task_id,
        file_path=task.result_pdf_path
    )

    if not is_valid:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=error_msg
        )

    # Return file
    filename = f"{task.filename or task_id}_result.pdf"
    return FileResponse(
        path=task.result_pdf_path,
        filename=filename,
        media_type="application/pdf"
    )


@router.post("/{task_id}/start", response_model=TaskResponse, summary="Start task processing")
async def start_task(
    task_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Start processing a pending task

    - **task_id**: Task UUID
    """
    try:
        task = task_service.update_task_status(
            db=db,
            task_id=task_id,
            user_id=current_user.id,
            status=TaskStatus.PROCESSING
        )

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

        logger.info(f"Started task {task_id} for user {current_user.email}")
        return task

    except HTTPException:
        raise
    except Exception as e:
        logger.exception(f"Failed to start task {task_id}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to start task: {str(e)}"
        )


@router.post("/{task_id}/cancel", response_model=TaskResponse, summary="Cancel task")
async def cancel_task(
    task_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Cancel a pending or processing task

    - **task_id**: Task UUID
    """
    try:
        # Get current task
        task = task_service.get_task_by_id(
            db=db,
            task_id=task_id,
            user_id=current_user.id
        )

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

        # Only allow canceling pending or processing tasks
        if task.status not in [TaskStatus.PENDING, TaskStatus.PROCESSING]:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail=f"Cannot cancel task in '{task.status.value}' status"
            )

        # Update to failed status with cancellation message
        task = task_service.update_task_status(
            db=db,
            task_id=task_id,
            user_id=current_user.id,
            status=TaskStatus.FAILED,
            error_message="Task cancelled by user"
        )

        logger.info(f"Cancelled task {task_id} for user {current_user.email}")
        return task

    except HTTPException:
        raise
    except Exception as e:
        logger.exception(f"Failed to cancel task {task_id}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to cancel task: {str(e)}"
        )


@router.post("/{task_id}/retry", response_model=TaskResponse, summary="Retry failed task")
async def retry_task(
    task_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Retry a failed task

    - **task_id**: Task UUID
    """
    try:
        # Get current task
        task = task_service.get_task_by_id(
            db=db,
            task_id=task_id,
            user_id=current_user.id
        )

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

        # Only allow retrying failed tasks
        if task.status != TaskStatus.FAILED:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail=f"Cannot retry task in '{task.status.value}' status"
            )

        # Reset task to pending status
        task = task_service.update_task_status(
            db=db,
            task_id=task_id,
            user_id=current_user.id,
            status=TaskStatus.PENDING,
            error_message=None
        )

        logger.info(f"Retrying task {task_id} for user {current_user.email}")
        return task

    except HTTPException:
        raise
    except Exception as e:
        logger.exception(f"Failed to retry task {task_id}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to retry task: {str(e)}"
        )