switch mp3 to tts, add genserver to app supervisor tree that periodically checks for newly connected devices and plays their associated tts message

lib/here_i_am/application.ex

@@ -16,6 +16,7 @@ defmodule HereIAm.Application do
       {Finch, name: HereIAm.Finch},
       # Start a worker by calling: HereIAm.Worker.start_link(arg)
       # {HereIAm.Worker, arg},
+      HereIAm.DeviceMonitor,
       # Start to serve requests, typically the last entry
       HereIAmWeb.Endpoint
     ]

lib/here_i_am/device_monitor.ex

@@ -0,0 +1,71 @@
+defmodule HereIAm.DeviceMonitor do
+  use GenServer
+
+  alias HereIAm.Devices
+
+  def start_link(_opts) do
+    GenServer.start_link(__MODULE__, %{}, name: __MODULE__)
+  end
+
+  @impl true
+  def init(state) do
+    schedule_check()
+    {:ok, Map.put(state, :connected_ips, %{})}
+  end
+
+  @impl true
+  def handle_info(:check_devices, state) do
+    connected_ips = get_connected_ips()
+
+    # Determine new devices and TTS
+    new_devices = MapSet.difference(MapSet.new(connected_ips), MapSet.new(Map.keys(state.connected_ips)))
+    Enum.each(new_devices, fn ip ->
+      case Devices.get_device_by_ip(ip) do
+        {:ok, device} -> play_message(device)
+        {:error, _reason} -> :ok
+      end
+    end)
+
+    # Update the registry
+    new_registry = Map.new(connected_ips, fn ip -> {ip, :connected} end)
+    schedule_check()
+    {:noreply, %{state | connected_ips: new_registry}}
+  end
+
+  defp schedule_check() do
+    Process.send_after(self(), :check_devices, 10_000)  # Check every 60 seconds
+  end
+
+  defp get_connected_ips() do
+    {output, 0} = System.cmd("sudo", ["arp-scan", "-l", "--localnet"])
+    parse_ips_from_arp_scan(output)
+  end
+
+  defp parse_ips_from_arp_scan(output) do
+    output
+    |> String.split("\n")
+    |> Enum.filter(&String.contains?(&1, "\t"))  # Filter lines containing tabs (IP-MAC pairs)
+    |> Enum.map(&String.split(&1, "\t"))
+    |> Enum.map(&List.first(&1))
+    |> Enum.filter(&valid_ip?/1)
+  end
+
+  defp valid_ip?(ip) do
+    case :inet.parse_address(to_charlist(ip)) do
+      {:ok, _} -> true
+      {:error, _} -> false
+    end
+  end
+
+  defp play_message(%{tts: tts_message}) do
+    cond do
+      not is_nil(tts_message) and tts_message != "" -> play_tts(tts_message)
+      true -> IO.puts("No audio or TTS message to play.")
+    end
+  end
+
+  defp play_tts(tts_message) do
+    IO.puts("Playing TTS message: #{tts_message}")
+    System.cmd("espeak", [tts_message])
+  end
+end

lib/here_i_am/devices.ex

@@ -101,4 +101,11 @@ defmodule HereIAm.Devices do
   def change_device(%Device{} = device, attrs \\ %{}) do
     Device.changeset(device, attrs)
   end
+
+  def get_device_by_ip(ip_address) do
+    case Repo.get_by(Device, ip_address: ip_address) do
+      nil -> {:error, :not_found}
+      device -> {:ok, device}
+    end
+  end
 end

lib/here_i_am/devices/device.ex

@@ -4,7 +4,7 @@ defmodule HereIAm.Devices.Device do
 
   schema "devices" do
     field :ip_address, :string
-    field :audio, :string
+    field :tts, :string
 
     timestamps(type: :utc_datetime)
   end
@@ -12,7 +12,7 @@ defmodule HereIAm.Devices.Device do
   @doc false
   def changeset(device, attrs) do
     device
-    |> cast(attrs, [:ip_address, :audio])
-    |> validate_required([:ip_address, :audio])
+    |> cast(attrs, [:ip_address, :tts])
+    |> validate_required([:ip_address, :tts])
   end
 end