app/dependencies.py

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import jwt, JWTError  # Ensure this is correctly imported
from utils.db import tinydb_helper  # Ensure this instance is correctly initialized elsewhere
from utils.jwt_utils import SECRET_KEY, ALGORITHM, decode_jwt

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

async def get_current_user(token: str = Depends(oauth2_scheme)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )

    expiry_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="No session found, please login again",
        headers={"WWW-Authenticate": "Bearer"},
    )    

    # Utilize the centralized JWT decoding and catch any JWT-related errors
    try:
        payload = decode_jwt(token)
    except JWTError:
        raise credentials_exception

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

    # Verify if the token is stored and valid as active session
    if not tinydb_helper.query_token(user_id, token):
        raise expiry_exception
    
    # Payload is already obtained and validated, so just return it or its specific parts as needed
    return {"user_id": user_id, "name": payload.get("name"), "role": payload.get("role")}