from __future__ import annotations

import os
from fastapi import Header, HTTPException


API_KEY_ENV = "API_KEY"


def require_api_key(x_api_key: str | None = Header(default=None)) -> None:
    expected = os.getenv(API_KEY_ENV, "")
    if not expected:
        # No API key configured → allow
        return
    if not x_api_key or x_api_key != expected:
        raise HTTPException(status_code=401, detail="invalid_api_key")