defmodule GenTimer do
  @moduledoc """
  Intervaled Timer, broadcasts `{:tick, state}` to topic subscribers every 1 second.

  Timer is initialized with a topic and duration in seconds. Once initialized the timer can be started and paused.
  Resetting the timer returns elasped time to zero.
  """

  def initialize(duration, topic) do
    with :ok <- GenTimer.Manager.initialize(duration, topic) do
      GenTimer.PubSub.subscribe(topic)
      {:ok, :initialized}
    else
      e -> e
    end
  end

  defdelegate start(name), to: GenTimer.Manager
  defdelegate pause(name), to: GenTimer.Manager
  defdelegate reset(name), to: GenTimer.Manager

  def subscribe(topic) do
    case lookup(topic) do
      [] ->
        {:error, :unknown}

      _ ->
        GenTimer.PubSub.subscribe(topic)
        {:ok, GenTimer.Manager.get_timer(topic)}
    end
  end

  def unsubscribe(topic) do
    GenTimer.PubSub.unsubscribe(topic)
  end

  def lookup(topic) do
    Registry.lookup(GenTimer.Registry.Manager, topic)
  end
end