dependencies.py

from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from sqlalchemy.orm import Session
from database.db_connect import get_db
from database.models import User
from core.security import verify_access_token

security_scheme = HTTPBearer(auto_error=False)

def get_current_user(
    credentials: HTTPAuthorizationCredentials | None = Depends(security_scheme),
    db: Session = Depends(get_db)
) -> User:
    """
    Dependency to get the currently authenticated user from the JWT token.
    Raises 401 Unauthorized if the token is invalid or expired, or if the user doesn't exist.
    """
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    if not credentials:
        raise credentials_exception

    token = credentials.credentials
    payload = verify_access_token(token)
    if payload is None:
        raise credentials_exception

    user_id: str = payload.get("sub")
    if user_id is None:
        raise credentials_exception

    user = db.query(User).filter(User.id == user_id).first()
    if user is None:
        raise credentials_exception

    return user