"""
File API Endpoints
Handles file upload, download, and session management.
"""

from fastapi import APIRouter, UploadFile, File, Form, Depends, HTTPException, Request, status
from fastapi.responses import FileResponse, StreamingResponse
from sqlalchemy.ext.asyncio import AsyncSession
from typing import List, Optional
from pathlib import Path

from app.core.auth import get_current_user_id
from app.core.database import get_db, AuditLogRepository
from app.core.redis_client import RedisSessionStore
from app.services.file_service import get_file_service, FileService
from app.services.metadata_service import get_metadata_service, MetadataService
from app.processors.file_detector import FileDetector
from app.models.file import (
    UploadSessionResponse,
    FileUploadResponse,
    BatchDownloadRequest
)


router = APIRouter()


@router.post("/upload", response_model=UploadSessionResponse)
async def upload_files(
    files: List[UploadFile] = File(...),
    metadata_source: str = Form(...),
    import_session_id: Optional[str] = Form(None),
    excel_session_id: Optional[str] = Form(None),
    template_name: Optional[str] = Form(None),
    request: Request = None,
    user_id: int = Depends(get_current_user_id),
    db: AsyncSession = Depends(get_db),
    file_service: FileService = Depends(get_file_service),
    metadata_service: MetadataService = Depends(get_metadata_service)
):
    """
    Upload files and generate metadata.

    Args:
        files: List of files to upload
        metadata_source: Source of metadata ('manual', 'ai', 'excel', 'import', 'template')
        import_session_id: Import session ID (for 'import' source)
        excel_session_id: Excel session ID (for 'excel' source)
        template_name: Template name (for 'template' source)
    """
    if not files:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="No files provided"
        )

    # Get import metadata if import source
    import_metadata = None
    if metadata_source == "import" and import_session_id:
        redis: RedisSessionStore = request.app.state.redis
        import_session = await redis.get_import_session(import_session_id)
        if import_session:
            import_metadata = import_session.get("metadata", {})

    # Process each file
    file_results = []

    for uploaded_file in files:
        try:
            # Save file
            file_info = await file_service.save_upload(uploaded_file, user_id)

            # Detect file type
            file_type = FileDetector.detect_file_type(file_info["filepath"])
            file_type_str = FileDetector.get_file_type_name(file_type)

            # Extract current metadata
            current_metadata = await metadata_service.extract_current_metadata(
                file_info["filepath"]
            )

            # Generate suggested metadata
            suggested_metadata = await metadata_service.generate_metadata(
                filepath=file_info["filepath"],
                filename=file_info["filename"],
                source=metadata_source,
                import_metadata=import_metadata,
                template_name=template_name
            )

            # Build file response
            file_result = FileUploadResponse(
                file_id=file_info["file_id"],
                filename=file_info["filename"],
                filepath=file_info["filepath"],
                file_type=file_type_str,
                size=file_info["size"],
                uploaded_at=file_info["uploaded_at"],
                current_metadata=current_metadata,
                suggested_metadata=suggested_metadata,
                metadata_source=metadata_source
            )

            file_results.append(file_result)

        except Exception as e:
            print(f"Error processing file {uploaded_file.filename}: {e}")
            # Continue with other files
            continue

    if not file_results:
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Failed to process any files"
        )

    # Create file session in Redis
    redis: RedisSessionStore = request.app.state.redis
    session_id = await redis.create_file_session(
        user_id=user_id,
        files_data=[file.dict() for file in file_results],
        metadata_source=metadata_source,
        ttl=3600  # 1 hour
    )

    # Log action
    await AuditLogRepository.log_action(
        db,
        user_id=user_id,
        action="file_upload",
        details=f"Uploaded {len(file_results)} files with {metadata_source} metadata"
    )

    return UploadSessionResponse(
        success=True,
        session_id=session_id,
        files=file_results,
        message=f"Uploaded {len(file_results)} files successfully"
    )


@router.get("/{file_id}/download")
async def download_file(
    file_id: str,
    request: Request,
    user_id: int = Depends(get_current_user_id),
    db: AsyncSession = Depends(get_db),
    file_service: FileService = Depends(get_file_service)
):
    """
    Download a single file by file_id.
    """
    # Get all file sessions for user (simplified - in production use better lookup)
    redis: RedisSessionStore = request.app.state.redis

    # Search through file sessions to find the file
    # Note: This is simplified. In production, you'd want a better indexing strategy
    pattern = f"file_session:*"
    session_keys = await redis.get_all_sessions(pattern)

    file_path = None
    filename = None

    for session_key in session_keys:
        session_data = await redis.redis.get(session_key)
        if session_data:
            import json
            session = json.loads(session_data)

            # Check if this session belongs to the user
            if session.get("user_id") != user_id:
                continue

            # Search for file with matching file_id
            for file_info in session.get("files", []):
                if file_info.get("file_id") == file_id:
                    file_path = file_info.get("filepath")
                    filename = file_info.get("filename")
                    break

            if file_path:
                break

    if not file_path or not file_service.file_exists(file_path):
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="File not found or access denied"
        )

    # Log action
    await AuditLogRepository.log_action(
        db,
        user_id=user_id,
        action="file_download",
        details=f"Downloaded file: {filename}"
    )

    return FileResponse(
        path=file_path,
        filename=filename,
        media_type="application/octet-stream"
    )


@router.post("/download-batch")
async def download_batch(
    download_request: BatchDownloadRequest,
    request: Request,
    user_id: int = Depends(get_current_user_id),
    db: AsyncSession = Depends(get_db),
    file_service: FileService = Depends(get_file_service)
):
    """
    Download multiple files as ZIP archive.
    """
    # Get file session
    redis: RedisSessionStore = request.app.state.redis
    session_data = await redis.get_file_session(download_request.session_id)

    if not session_data or session_data.get("user_id") != user_id:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Session not found or access denied"
        )

    # Get files from session
    all_files = session_data.get("files", [])

    # Filter by file_indices
    selected_files = [
        all_files[i] for i in download_request.file_indices
        if i < len(all_files)
    ]

    if not selected_files:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="No valid files selected"
        )

    # Create ZIP archive
    from datetime import datetime
    zip_filename = f"oliver_metadata_files_{datetime.now().strftime('%Y%m%d_%H%M%S')}.zip"

    zip_path = await file_service.create_zip_archive(
        files=selected_files,
        output_filename=zip_filename
    )

    # Log action
    await AuditLogRepository.log_action(
        db,
        user_id=user_id,
        action="batch_download",
        details=f"Downloaded {len(selected_files)} files as ZIP"
    )

    return FileResponse(
        path=str(zip_path),
        filename=zip_filename,
        media_type="application/zip"
    )


@router.delete("/session/{session_id}")
async def cleanup_session(
    session_id: str,
    request: Request,
    user_id: int = Depends(get_current_user_id),
    db: AsyncSession = Depends(get_db),
    file_service: FileService = Depends(get_file_service)
):
    """
    Cleanup session - delete files and session data.
    """
    # Get file session
    redis: RedisSessionStore = request.app.state.redis
    session_data = await redis.get_file_session(session_id)

    if not session_data or session_data.get("user_id") != user_id:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Session not found or access denied"
        )

    # Delete all files in session
    files = session_data.get("files", [])
    deleted_count = file_service.cleanup_session_files(files)

    # Delete session from Redis
    await redis.delete_file_session(session_id)

    # Log action
    await AuditLogRepository.log_action(
        db,
        user_id=user_id,
        action="session_cleanup",
        details=f"Cleaned up session {session_id}, deleted {deleted_count} files"
    )

    return {
        "success": True,
        "message": f"Session cleaned up, deleted {deleted_count} files"
    }


@router.get("/stats")
async def get_storage_stats(
    user_id: int = Depends(get_current_user_id),
    file_service: FileService = Depends(get_file_service)
):
    """
    Get storage statistics (admin/debug endpoint).
    """
    stats = file_service.get_storage_stats()
    return stats