defmodule Whisper.Counter do
  use Agent

  def start_link(_), do: Agent.start_link(fn -> %{} end, name: __MODULE__)

  def next(ref) do
    Agent.get_and_update(__MODULE__, fn state ->
      current = Map.get(state, ref, 0) + 1
      {current, Map.put(state, ref, current)}
    end)
  end

  def reset(ref) do
    Agent.update(__MODULE__, &Map.delete(&1, ref))
  end
end