defmodule LineMessage.Macro do

  defmacro __using__(_) do
    quote do
      import LineMessage.Macro
      alias LineMessage.Event
      alias LineMessage.Message
      alias LineMessage.Reply
      Agent.start_link(fn -> Map.new end, name: EventAgent)
      :ok
    end
  end

  defmacro message(type, [do: block]) do
    quote do
      event_on("message", unquote(type), fn -> unquote(block) end)
    end
  end

  def event_on(event_type, message_type, func) do
    LineMessage.Event.on(event_type, fn evt ->
      if evt.type == Atom.to_string(message_type) do
        Agent.update(EventAgent, &Map.put(&1, self(), evt))
        func.()
      end
    end)
  end

  def event do
    {:ok, evt} = Agent.get(EventAgent, &Map.fetch(&1, self()))
    evt
  end
end