Make stats feed update automatically

lib/last_fm/feed.ex

@@ -14,11 +14,18 @@ defmodule LastFm.Feed do
   def update(tracks) do
     data = Enum.map(tracks, fn t -> {t.scrobbled_at_uts, t} end)
 
+    :ets.delete_all_objects(__MODULE__)
     :ets.insert(__MODULE__, data)
+
+    Phoenix.PubSub.broadcast(LastFm.PubSub, "feed:update", %{tracks: data})
   end
 
   def all do
     :ets.tab2list(__MODULE__)
     |> Enum.reverse()
   end
+
+  def subscribe do
+    Phoenix.PubSub.subscribe(LastFm.PubSub, "feed:update")
+  end
 end

lib/last_fm/refresh.ex

@@ -5,12 +5,13 @@ defmodule LastFm.Refresh do
 
   alias LastFm.Feed
 
-  @refresh_interval System.convert_time_unit(30, :second, :millisecond)
+  @refresh_interval System.convert_time_unit(10, :second, :millisecond)
 
   def start_link(config) do
     GenServer.start_link(__MODULE__, config, name: __MODULE__)
   end
 
+  @impl true
   def init(config) do
     if enabled?(config) do
       {:ok, config, {:continue, :refresh}}
@@ -19,6 +20,7 @@ defmodule LastFm.Refresh do
     end
   end
 
+  @impl true
   def handle_continue(:refresh, config) do
     case config.api.get_recent_tracks(config.user, config.api_key) do
       {:ok, tracks} ->
@@ -33,6 +35,21 @@ defmodule LastFm.Refresh do
     end
   end
 
+  @impl true
+  def handle_info(:refresh, config) do
+    case config.api.get_recent_tracks(config.user, config.api_key) do
+      {:ok, tracks} ->
+        Feed.update(tracks)
+        Process.send_after(self(), :refresh, @refresh_interval)
+        {:noreply, config}
+
+      {:error, _reason} ->
+        # TODO: think about failure scenario - error is logged at the API level
+        Process.send_after(self(), :refresh, @refresh_interval)
+        {:noreply, config}
+    end
+  end
+
   defp enabled?(config) do
     config.api && config.api_key
   end

lib/last_fm/supervisor.ex

@@ -10,6 +10,7 @@ defmodule LastFm.Supervisor do
     :ok = LastFm.Feed.create_table!()
 
     children = [
+      {Phoenix.PubSub, name: LastFm.PubSub},
       {LastFm.Refresh, %{api: api(), user: "cloud8421", api_key: api_key()}}
     ]
 

lib/music_library_web/live/stats_live/index.ex

@@ -20,6 +20,10 @@ defmodule MusicLibraryWeb.StatsLive.Index do
 
     recent_tracks = LastFm.Feed.all()
 
+    if connected?(socket) do
+      LastFm.Feed.subscribe()
+    end
+
     {:ok,
      socket
      |> assign(
@@ -34,6 +38,17 @@ defmodule MusicLibraryWeb.StatsLive.Index do
      )}
   end
 
+  def handle_info(%{tracks: tracks}, socket) do
+    socket =
+      if socket.assigns.recent_tracks !== tracks do
+        assign(socket, :recent_tracks, tracks)
+      else
+        socket
+      end
+
+    {:noreply, socket}
+  end
+
   # The Tailwind build step requires all needed classes to be explicitly referenced
   # in the source code, and not dynamically generated. This implies that one cannot
   # (for example) interpolate a number in a class name.