from flask import Response, request


def handle_etag(response: Response) -> Response:
    if request.method == "GET":
        response.add_etag()
        etag, weak = response.get_etag()
        requested_etags = request.if_none_match.as_set()

        if len(requested_etags) > 0:
            request_etag = requested_etags.pop()

            if request_etag == etag:
                response.status_code = 304

    return response