listeners.put(state, listener);
    }

    return slackApi.authorizeUrl(scopes, redirectUrl(), state, team);
  }

  private ByteString randomToken() {
    byte[] bytes = new byte[16];
    secureRandom.nextBytes(bytes);
    return ByteString.of(bytes);
  }

  private HttpUrl redirectUrl() {
    return mockWebServer.url("/oauth/");
  }

  }

  @Override public void onMessage(WebSocket webSocket, String text) {
    System.out.println("MESSAGE: " + text);
  }

  @Override public void onMessage(WebSocket webSocket, ByteString bytes) {
    System.out.println("MESSAGE: " + bytes.hex());
  }

  @Override public void onClosing(WebSocket webSocket, int code, String reason) {
    webSocket.close(1000, null);
    System.out.println("CLOSE: " + code + " " + reason);
  }

        long totalBytesRead = 0L;

        @Override public long read(Buffer sink, long byteCount) throws IOException {
          long bytesRead = super.read(sink, byteCount);
          // read() returns the number of bytes read, or -1 if this source is exhausted.
          totalBytesRead += bytesRead != -1 ? bytesRead : 0;
          progressListener.update(totalBytesRead, responseBody.contentLength(), bytesRead == -1);
          return bytesRead;

    webSocket = slackApi.rtm(rtmStartResponse.url, this);
  }

  // TODO(jwilson): can I read the response body? Do I have to?
  //                the body from slack is a 0-byte-buffer
  @Override public synchronized void onOpen(WebSocket webSocket, Response response) {
    System.out.println("onOpen: " + response);
  }

  // TOOD(jwilson): decode incoming messages and dispatch them somewhere.