"""
Import API Endpoints
Handles CSV/Excel/JSON import with column mapping.
"""

from fastapi import APIRouter, UploadFile, File, Depends, HTTPException, Request, status
from sqlalchemy.ext.asyncio import AsyncSession
from pathlib import Path
import secrets

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.processors.metadata_importer import MetadataImporter
from app.models.file import (
    ImportFileResponse,
    ImportMappingConfig,
    ExcelSheetPreviewRequest
)


router = APIRouter()


@router.post("/file", response_model=ImportFileResponse)
async def upload_import_file(
    import_file: UploadFile = File(...),
    request: Request = None,
    user_id: int = Depends(get_current_user_id),
    db: AsyncSession = Depends(get_db),
    file_service: FileService = Depends(get_file_service)
):
    """
    Upload CSV/Excel/JSON file for metadata import.
    """
    # Save import file
    file_info = await file_service.save_upload(import_file, user_id)

    # Detect file type
    file_ext = Path(file_info["filename"]).suffix.lower()
    import_type = file_ext.replace('.', '')  # csv, xlsx, json

    # Preview file structure
    importer = MetadataImporter()
    try:
        columns, sample_data, suggestions = importer.preview_file_structure(file_info["filepath"])

        # For Excel files, get sheet names
        sheet_names = None
        if import_type == 'xlsx':
            import openpyxl
            wb = openpyxl.load_workbook(file_info["filepath"])
            sheet_names = wb.sheetnames

        # Create import session in Redis
        redis: RedisSessionStore = request.app.state.redis
        import_session_id = await redis.create_import_session(
            user_id=user_id,
            import_type=import_type,
            filename=file_info["filename"],
            filepath=file_info["filepath"]
        )

        # Log action
        await AuditLogRepository.log_action(
            db,
            user_id=user_id,
            action="import_upload",
            details=f"Uploaded {import_type} import file: {file_info['filename']}"
        )

        return ImportFileResponse(
            success=True,
            import_session_id=import_session_id,
            filename=file_info["filename"],
            import_type=import_type,
            columns=columns,
            sheet_names=sheet_names,
            sample_data=sample_data[:5] if sample_data else None,  # First 5 rows
            row_count=len(sample_data) if sample_data else 0
        )

    except Exception as e:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Failed to parse import file: {str(e)}"
        )


@router.post("/excel/preview")
async def preview_excel_sheet(
    preview_request: ExcelSheetPreviewRequest,
    request: Request,
    user_id: int = Depends(get_current_user_id)
):
    """
    Preview specific Excel sheet.
    """
    # Get import session
    redis: RedisSessionStore = request.app.state.redis
    session_data = await redis.get_import_session(preview_request.excel_session_id)

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

    # Preview sheet
    importer = MetadataImporter()
    try:
        import pandas as pd
        df = pd.read_excel(session_data["filepath"], sheet_name=preview_request.sheet_name)

        return {
            "success": True,
            "columns": df.columns.tolist(),
            "sample_data": df.head(5).to_dict('records'),
            "row_count": len(df)
        }
    except Exception as e:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Failed to preview sheet: {str(e)}"
        )


@router.post("/configure")
async def configure_import_mapping(
    mapping_config: ImportMappingConfig,
    request: Request,
    user_id: int = Depends(get_current_user_id),
    db: AsyncSession = Depends(get_db)
):
    """
    Configure column mapping for import file.
    """
    # Get import session
    redis: RedisSessionStore = request.app.state.redis
    session_data = await redis.get_import_session(mapping_config.import_session_id)

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

    # Build column mapping dict
    column_mapping = {
        m.source_column: m.target_field
        for m in mapping_config.column_mappings
    }

    # Import metadata with mapping
    importer = MetadataImporter()
    try:
        metadata_map = importer.import_with_mapping(
            session_data["filepath"],
            column_mapping,
            sheet_name=mapping_config.sheet_name
        )

        # Store metadata in session
        await redis.update_import_metadata(
            mapping_config.import_session_id,
            metadata_map
        )

        # Log action
        await AuditLogRepository.log_action(
            db,
            user_id=user_id,
            action="import_configure",
            details=f"Configured import mapping: {len(metadata_map)} records"
        )

        return {
            "success": True,
            "message": f"Import configured with {len(metadata_map)} records"
        }

    except Exception as e:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Failed to configure import: {str(e)}"
        )