defmodule Pingpong.PongProcess do
  use GenServer

  def start_link(state \\ nil), do: GenServer.start_link(__MODULE__, state, name: __MODULE__)

  def init(state) do
    {:ok, state}
  end

  def handle_info(:ping, state) do
    pong_process_pid = self()
    ping_process_pid = Process.whereis(Pingpong.PingProcess)

    IO.puts("PONG from #{inspect(pong_process_pid)} to #{inspect(ping_process_pid)}")
    Process.sleep(1000)
    send(ping_process_pid, :pong)

    {:noreply, state}
  end
end