import typing
from urllib.parse import unquote, urlparse

from flask import request, current_app


def get_auth_proxy() -> typing.Optional[str]:
    auth_proxy = unquote(request.args.get("auth_proxy", ""))
    if auth_proxy and urlparse(
        auth_proxy
    ).netloc not in current_app.config.get("ALLOWED_HOSTS"):
        auth_proxy = None
    return auth_proxy