app/core/dependencies.py

# app/core/dependencies.py
# FastAPI dependency injection — auth guards, role checks, shared helpers

from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from app.core.security import decode_access_token
from app.db.models.user import UserDocument, UserRole

_bearer = HTTPBearer(auto_error=False)


async def get_current_user(
    credentials: HTTPAuthorizationCredentials | None = Depends(_bearer),
) -> UserDocument:
    """Extract and validate JWT; return the authenticated UserDocument."""
    if not credentials:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
            headers={"WWW-Authenticate": "Bearer"},
        )

    payload = decode_access_token(credentials.credentials)
    if not payload:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid or expired token",
        )

    user = await UserDocument.get(payload["sub"])
    if not user or not user.is_active:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User not found or deactivated",
        )
    return user


def require_role(*roles: UserRole):
    """Factory that returns a dependency requiring one of the given roles."""
    async def _check(user: UserDocument = Depends(get_current_user)) -> UserDocument:
        if user.role not in roles:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail=f"Role '{user.role}' is not permitted for this action",
            )
        return user
    return _check