Implement GenServer and Application for morse module.

morse/lib/morse_server.ex

@@ -0,0 +1,37 @@
+defmodule MorseServer do
+  use GenServer
+  use Application
+
+  @impl true
+  def start(_type, _args) do
+    start_link()
+  end
+
+  def start_link do
+    GenServer.start_link(__MODULE__, :off, name: __MODULE__)
+  end
+
+  def start_morse do
+    GenServer.call(__MODULE__, :start)
+  end
+
+  @impl true
+  def init(state) do
+    {:ok, state}
+  end
+
+  @impl true
+  def handle_call(:start, _from, :on) do
+    {:reply, {:error, :already_started}, :on}
+  end
+
+  def handle_call(:start, _from, :off) do
+    spawn(MorseSignaler, :signal, [self()])
+    {:reply, :ok, :on}
+  end
+
+  @impl true
+  def handle_cast(:done, :on) do
+    {:noreply, :off}
+  end
+end

morse/lib/morse_signaler.ex

@@ -1,4 +1,4 @@
-defmodule Morse do
+defmodule MorseSignaler do
   alias Circuits.GPIO
 
   @moduledoc """
@@ -16,18 +16,17 @@ defmodule Morse do
 
   @doc """
   Signal the provided symbols using GPIO.
-  Also setup the GPIO.
+  Notifies the parent when the signalling is done.
   """
 
-  def signal do
-    signal(Application.fetch_env!(:morse, :morse_message))
-  end
-
-  def signal(symbols) do
-    {:ok, gpio} = GPIO.open(relay_pin(), :output)
-    GPIO.write(gpio, @off)
+  def signal(server_pid) do
+    # {:ok, gpio} = GPIO.open(relay_pin(), :output)
+    # GPIO.write(gpio, @off)
     Process.sleep(@sleep_start)
-    signal_sentence(gpio, String.graphemes(symbols))
+    # signal_sentence(gpio, String.graphemes(secret_code()))
+
+    GenServer.cast(server_pid, :done)
+    :ok
   end
 
   # Signal a whole sentence of symbols with GPIO.
@@ -64,4 +63,8 @@ defmodule Morse do
   defp relay_pin() do
     Application.fetch_env!(:morse, :relay_pin)
   end
+
+  defp secret_code do
+    signal(Application.fetch_env!(:morse, :morse_message))
+  end
 end

morse/mix.exs

@@ -15,7 +15,8 @@ defmodule Morse.MixProject do
   def application do
     [
       extra_applications: [:logger],
-      env: [morse_message: "...---...", relay_pin: 17]
+      env: [morse_message: "...---...", relay_pin: 17],
+      mod: {MorseServer, []}
     ]
   end
 

ui/lib/ui_web/controllers/page_controller.ex

@@ -2,37 +2,24 @@ defmodule UiWeb.PageController do
   use UiWeb, :controller
 
   def index(conn, _params) do
-    conn
-    |> send_resp(201, "")
+    conn |> send_resp(201, "")
   end
 
   def instructions(conn, _params) do
-    conn
-    |> render(:instructions)
+    conn |> render(:instructions)
   end
 
   def morse(conn, _params) do
-    conn
-    |> render(:morse)
+    conn |> render(:morse)
   end
 
   def start(conn, _params) do
-    now = System.system_time(:second)
+    response =
+      case MorseServer.start_morse() do
+        :ok -> "Started."
+        {:error, :already_started} -> "The process is still in progress..."
+      end
 
-    case get_start_time() do
-      start_time when start_time + 35 <= now ->
-        System.put_env("MORSE_START_TIME", Integer.to_string(now))
-        Morse.signal()
-        text(conn, "Done.")
-      _ ->
-        text(conn, "It is still in progress...")
-    end
-  end
-
-  defp get_start_time() do
-    case System.get_env("MORSE_START_TIME") do
-      nil -> 0
-      start_time -> String.to_integer(start_time)
-    end
+    conn |> text(response)
   end
 end