# ============================================================
# app/services/user_service.py - User Business Logic
# ============================================================

import logging
from fastapi import HTTPException, status
from bson import ObjectId
from app.database import get_db
from app.models.user import User
from datetime import datetime

logger = logging.getLogger(__name__)

class UserService:
    """User Service for managing user profiles"""
    
    @staticmethod
    async def get_user_profile(user_id: str) -> dict:
        """
        Get user profile by ID
        
        Args:
            user_id: MongoDB user ID
        
        Returns:
            User profile data
        """
        # Validate MongoDB ID format
        if not ObjectId.is_valid(user_id):
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Invalid user ID format"
            )
        
        db = await get_db()
        users_collection = db["users"]
        
        try:
            user = await users_collection.find_one({"_id": ObjectId(user_id)})
            
            if not user:
                raise HTTPException(
                    status_code=status.HTTP_404_NOT_FOUND,
                    detail="User not found"
                )
            
            logger.info(f"User profile fetched: {user_id}")
            
            return {
                "success": True,
                "message": "User profile retrieved successfully",
                "data": User.format_response(user),
            }
        except HTTPException:
            raise
        except Exception as e:
            logger.error(f"Error fetching user profile: {str(e)}")
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail="Failed to fetch user profile"
            )
    
    @staticmethod
    async def get_current_user_profile(user_id: str) -> dict:
        """
        Get current logged-in user profile
        
        Args:
            user_id: User ID from JWT token
        
        Returns:
            Current user profile
        """
        return await UserService.get_user_profile(user_id)
    
    @staticmethod
    async def update_user_profile(user_id: str, update_data: dict) -> dict:
        """
        Update user profile
        
        Args:
            user_id: MongoDB user ID
            update_data: Fields to update
        
        Returns:
            Updated user profile
        """
        # Validate MongoDB ID format
        if not ObjectId.is_valid(user_id):
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Invalid user ID format"
            )
        
        # Only allow updating certain fields
        allowed_fields = ["firstName", "lastName", "phone", "bio", "profilePicture"]
        filtered_data = {
            k: v for k, v in update_data.items()
            if k in allowed_fields
        }
        
        if not filtered_data:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="No valid fields to update"
            )
        
        db = await get_db()
        users_collection = db["users"]
        
        filtered_data["updatedAt"] = datetime.utcnow()
        
        try:
            user = await users_collection.find_one_and_update(
                {"_id": ObjectId(user_id)},
                {"$set": filtered_data},
                return_document=True,
            )
            
            if not user:
                raise HTTPException(
                    status_code=status.HTTP_404_NOT_FOUND,
                    detail="User not found"
                )
            
            logger.info(f"User profile updated: {user_id}")
            
            return {
                "success": True,
                "message": "User profile updated successfully",
                "data": User.format_response(user),
            }
        except HTTPException:
            raise
        except Exception as e:
            logger.error(f"Error updating user profile: {str(e)}")
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail="Failed to update user profile"
            )

# Create singleton instance
user_service = UserService()