defp drop_topic(state, topic) do
  :ok = WebinarGeekWeb.Endpoint.unsubscribe(topic)
  Logger.warn("Removing #{topic}, with #{state.topics[topic]} keys")
  %{state | topics: Map.delete(state.topics, topic)}
end

defp traverse_leaves(state, leaves) do
  Enum.reduce(leaves, state, fn {subscription_id, _metas}, acc ->
    case Map.fetch(acc.tab_counter, subscription_id) do
      {:ok, number_of_tabs} ->
        if number_of_tabs - 1 <= 0 do
          ViewerPresence.log_unsubscribe(subscription_id)
          remove_subscription_from_state(state, subscription_id)
        else
          set_number_of_tabs(acc, subscription_id, number_of_tabs - 1)
        end

      _ ->
        acc
    end
  end)
end