defmodule Microprints.TestPubSub do
  @moduledoc """
  Test helper for starting a Phoenix.PubSub server.

  Provides `start_link/1` to start a PubSub server and returns the
  server name for use with MicroprintCache.
  """

  @doc """
  Starts a test PubSub server and returns its name.
  """
  def start_link(opts \\ []) do
    name = opts[:name] || Microprints.TestPubSub

    child_spec = Phoenix.PubSub.child_spec(name: name, adapter: Phoenix.PubSub.PG2)

    # Start a temporary supervisor to host the PubSub server
    case Supervisor.start_link([child_spec], strategy: :one_for_one) do
      {:ok, sup_pid} ->
        Process.put(:test_pubsub_supervisor, sup_pid)

      {:error, {:already_started, sup_pid}} ->
        Process.put(:test_pubsub_supervisor, sup_pid)
    end

    name
  end

  @doc """
  Stops the test PubSub server.
  """
  def stop do
    if sup_pid = Process.get(:test_pubsub_supervisor) do
      Supervisor.stop(sup_pid)
      Process.delete(:test_pubsub_supervisor)
    end
  end
end