backend/app/core/auth_dependancy.py

from fastapi import Depends, HTTPException
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from jose import jwt, JWTError
from app.core.config import settings
from sqlalchemy.orm import Session
from app.db.session import get_db
from app.models.user_model import User
from typing import Optional

security = HTTPBearer()
optional_security = HTTPBearer(auto_error=False)

def get_current_user(
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db)
):
    token = credentials.credentials
    
    try:
        payload = jwt.decode(token, settings.JWT_SECRET, algorithms=["HS256"])
        user_id: int = payload.get("user_id")
        
        if user_id is None:
            raise HTTPException(status_code=401, detail="Invalid token")
        
    except JWTError:
        raise HTTPException(status_code=401, detail="Invalid token")
    
    user = db.query(User).filter(User.id == user_id).first()
    
    if user is None:
        raise HTTPException(status_code=401, detail="User not found")

    return user

def get_optional_user(
    credentials:
        Optional[HTTPAuthorizationCredentials] = Depends(optional_security),
    db: Session = Depends(get_db)
):
    if not credentials:
        return None
    
    token = credentials.credentials
    try:
        payload = jwt.decode(token, settings.JWT_SECRET, algorithms=["HS256"])
        user_id = payload.get("user_id")
        if not user_id:
            return None
        return db.query(User).filter(User.id == user_id).first()
    except JWTError:
        return None