hemdal

defmodule Hemdal.Event.Mock do
  @moduledoc """
  Consume the events generated by the system and send all of these events
  to the process which run `start_link/0`. The even is `Hemdal.Event.t()`.
  """
  use GenStage

  @event_manager Hemdal.Event

  @doc """
  It is starting a consumer, linked to the caller process, and sending
  all of the events to the caller process.
  """
  @spec start_link() :: {:ok, pid()}
  def start_link do
    {:ok, _pid} = GenStage.start_link(__MODULE__, [self()])
  end

  @doc """
  Stop the consumer, while it's linked to the caller process it's a good
  idea to stop it.
  """
  @spec stop(GenServer.server()) :: :ok
  defdelegate stop(pid), to: GenStage

  @impl GenStage
  @doc false
  def init([pid]) do
    {:consumer, pid, subscribe_to: [@event_manager]}
  end

  @impl true
  @doc false
  def handle_events(events, from, pid) do
    Enum.each(events, &send(pid, {:event, from, &1}))
    {:noreply, [], pid}
  end
end