from mod_pywebsocket import common, msgutil


def web_socket_do_extra_handshake(request):
    pmce_offered = False

    if request.ws_requested_extensions is not None:
        for extension_request in request.ws_requested_extensions:
            if extension_request.name() == "permessage-deflate":
                pmce_offered = True

    if pmce_offered is False:
        raise ValueError("permessage-deflate not offered")


def web_socket_transfer_data(request):
    while True:
        rcvd = msgutil.receive_message(request)
        opcode = request.ws_stream.get_last_received_opcode()
        if opcode == common.OPCODE_BINARY:
            msgutil.send_message(request, rcvd, binary=True)
        elif opcode == common.OPCODE_TEXT:
            msgutil.send_message(request, rcvd)