app/core/dependencies.py

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from sqlalchemy.orm import selectinload
from jose import JWTError, jwt
from ..db.database import get_db
from ..db.models import User
from ..core.config import settings

oauth2_scheme = OAuth2PasswordBearer(tokenUrl=f"{settings.API_V1_STR}/auth/login")

async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: AsyncSession = Depends(get_db)
):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        user_id: str = payload.get("sub")
        if user_id is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    
    stmt = select(User).options(selectinload(User.roles)).where(User.id == int(user_id))
    result = await db.execute(stmt)
    user = result.scalar_one_or_none()
    
    if user is None:
        raise credentials_exception
    return user

async def get_current_active_user(
    current_user: User = Depends(get_current_user)
):
    if not current_user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user

async def get_current_superuser(
    current_user: User = Depends(get_current_user)
):
    if not current_user.is_superuser:
        raise HTTPException(
            status_code=403, detail="The user doesn't have enough privileges"
        )
    return current_user