from datetime import datetime, timedelta
from fastapi import HTTPException, status, Request, Depends
from fastapi.security import OAuth2PasswordBearer
from jose import jwt, JWTError
from db.mongo import users_collection
from core.config import SECRET_KEY, ALGORITHM, ACCESS_TOKEN_EXPIRE_MINUTES
import logging
from typing import Optional

logger = logging.getLogger(__name__)

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/auth/login")

def create_access_token(data: dict) -> str:
    try:
        to_encode = data.copy()
        expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
        to_encode.update({"exp": expire})
        encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
        logger.info(f"Token created for {data.get('sub')}")
        return encoded_jwt
    except Exception as e:
        logger.error(f"Token creation failed: {str(e)}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Token creation failed"
        )

async def validate_token(token: str) -> dict:
    try:
        if not token:
            logger.error("Empty token provided")
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="No token provided"
            )

        # Handle cases where 'Bearer ' prefix might be present
        if token.startswith("Bearer "):
            token = token[7:]
            logger.debug("Removed 'Bearer ' prefix from token")

        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        email = payload.get("sub")
        if not email:
            logger.error("Token missing 'sub' claim")
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Invalid token format"
            )
            
        logger.info(f"Token validated for {email}")
        return payload
        
    except jwt.ExpiredSignatureError:
        logger.error("Token expired")
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Token expired"
        )
    except JWTError as e:
        logger.error(f"Token validation failed: {str(e)}")
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Could not validate credentials"
        )

async def get_current_user(request: Request, token: str = Depends(oauth2_scheme)) -> dict:
    logger.info(f"Incoming request headers: {dict(request.headers)}")
    logger.info(f"Raw token received: {token[:15]}...")  # Log first 15 chars for security
    
    try:
        payload = await validate_token(token)
        email = payload.get("sub")
        
        user = await users_collection.find_one({"email": email})
        if not user:
            logger.error(f"User not found in DB: {email}")
            raise HTTPException(
                status_code=status.HTTP_404_NOT_FOUND,
                detail="User not found"
            )
            
        logger.info(f"User authenticated: {email}")
        return user
        
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Unexpected error in get_current_user: {str(e)}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Internal server error"
        )