defmodule <%= @mod %>.Scene.Sensor do
  use Scenic.Scene

  alias Scenic.Graph
  alias Scenic.ViewPort
  alias Scenic.Sensor

  import Scenic.Primitives
  import Scenic.Components

  alias <%= @mod %>.Component.Nav
  alias <%= @mod %>.Component.Notes

  @body_offset      80
  @font_size        160
  @degrees          "°"

  @notes  """
    \"Sensor\" is a simple scene that displays data from a simulated sensor.
    The sensor is in /lib/sensors/temperature and uses Scenic.Sensor
    The buttons are placeholders showing custom alignment.
  """

  #============================================================================
  # setup

  #--------------------------------------------------------
  def init( _, opts ) do
    {:ok, %ViewPort.Status{size: {vp_width, _}}} = opts[:viewport]
    |> ViewPort.info()
    col = vp_width / 6

    # build the graph
    graph = Graph.build( font: :roboto, font_size: 16, theme: :dark )
    # text input
    |> group(fn(graph) ->
      graph
      |> text(
        "", id: :temperature, text_align: :center,
        font_size: @font_size, translate: {vp_width / 2, @font_size}
      )
      |> group( fn(g) ->
        g
        |> button( "Calibrate", width: col * 4, height: 46, theme: :primary )
        |> button(
          "Maintenance", width: col * 2 - 6, height: 46,
          theme: :secondary, translate: {0, 60}
        )
        |> button(
          "Settings", width: col * 2 - 6, height: 46,
          theme: :secondary, translate: {col * 2 + 6, 60}
        )
      end, translate: {col, @font_size + 60}, button_font_size: 24)

    end, translate: {0, @body_offset} )
    
    # NavDrop and Notes are added last so that they draw on top
    |> Nav.add_to_graph( __MODULE__ )
    |> Notes.add_to_graph( @notes )
    |> push_graph()

    # subscribe to the simulated temperature sensor
    Sensor.subscribe( :temperature )

    {:ok, graph}
  end

  #--------------------------------------------------------
  # receive updates from the simulated temperature sensor
  def handle_info( {:sensor, :data, {:temperature, kelvin, _}}, graph ) do

    temperature = (9/5) * (kelvin - 273) + 32        # fahrenheit
    # temperature = kelvin - 273                      # celcius
    |> :erlang.float_to_binary(decimals: 1)

    graph
    # center the temperature on the viewport
    |> Graph.modify( :temperature, &text(&1, temperature <> @degrees) )
    |> push_graph()

    {:noreply, graph}
  end

end