augie/webapp/lib/augie_web/live/dashboard_live.ex

defmodule AugieWeb.DashboardLive do
  use Phoenix.LiveView, layout: {AugieWeb.LayoutView, "live.html"}
  alias Augie.Firmata
  alias Phoenix.PubSub

  @moduledoc """
  A live view which shows or hides the dashboard based on whether the Teensy USB
  serial connection was found.
  """

  def mount(_params, _context, socket) do
    if connected?(socket), do: PubSub.subscribe(Augie.PubSub, "serial_telemetry")

    {:ok, assign(socket, connected: Firmata.connected?(), uarts: Circuits.UART.enumerate())}
  end

  def handle_info({:connected, false}, socket) do
    {:noreply, assign(socket, connected: false, uarts: Circuits.UART.enumerate())}
  end

  def handle_info({:connected, _}, socket) do
    {:noreply, assign(socket, connected: true, uarts: [])}
  end
end