exred_node_gpio_out

defmodule Exred.Node.GPIOOut do
  @moduledoc """
  Sends data to a GPIO pin.
  
  Uses [Elixir ALE](https://github.com/fhunleth/elixir_ale) to interface with GPIO.
  
  ##Incoming Message format
  
    msg = %{payload :: 0 | 1 | true | false}
  
  ##Outgoing Message format
  
    msg = %{
      payload :: :ok | :error,
      error :: term
    }
  
  """


  @name "GPIO Out"
  @category "output"
  @info @moduledoc
  @config %{
    name: %{
      info: "Visible node name",
      value: @name, 
      type: "string", 
      attrs: %{max: 20}
    },
    pin_number: %{
      info: "GPIO pin number the node will write to",
      value: 0, 
      type: "number", 
      attrs: %{min: 0}
    },
  }
  @ui_attributes %{
    fire_button: false,
    right_icon: "send",
    config_order: [:name, :pin_number]
  }


  use Exred.Library.NodePrototype
  alias ElixirALE.GPIO
  require Logger


  @impl true
  def node_init(state) do
    {Map.put(state, :init, :starting), 500}
  end
  
  @impl true
  def handle_msg(:timeout, %{init: :starting} = state) do
    # start GPIO process
    {:ok, pid} = GPIO.start_link(state.config.pin_number.value, :output)

    new_state = state 
    |> Map.put(:pid, pid)
    |> Map.put(:init, :done)
    {nil, new_state}
  end

  def handle_msg(msg, %{init: :starting} = state) do
    Logger.warn "UNHANDLED MSG DURING INIT node: #{state.node_id} #{get_in(state.config, [:name, :value])} msg: #{inspect msg}"
    {nil, state}
  end
  
  def handle_msg(msg, %{init: :done} = state) do 
    msg_out = case GPIO.write(state.pid, msg.payload) do
      :ok -> %{msg | payload: :ok}
      {:error, error} -> 
        # put the error info in the outgoing msg
        %{msg | payload: :error} |> Map.put(:error, error)
    end
    
    {msg_out, state}
  end
end