Refactor last_fm configuration

Move all configuration outside of the LastFm module, so that it's not
polluted with references to the parent music_library application.

lib/last_fm/refresh.ex

@@ -5,14 +5,14 @@ defmodule LastFm.Refresh do
 
   alias LastFm.Feed
 
-  @refresh_interval System.convert_time_unit(60, :second, :millisecond)
-
   def start_link(config) do
     GenServer.start_link(__MODULE__, config, name: __MODULE__)
   end
 
   @impl true
   def init(config) do
+    config = Map.new(config)
+
     if enabled?(config) do
       {:ok, config, {:continue, :refresh}}
     else
@@ -25,12 +25,12 @@ defmodule LastFm.Refresh 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)
+        Process.send_after(self(), :refresh, config.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)
+        Process.send_after(self(), :refresh, config.refresh_interval)
         {:noreply, config}
     end
   end
@@ -40,12 +40,12 @@ defmodule LastFm.Refresh 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)
+        Process.send_after(self(), :refresh, config.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)
+        Process.send_after(self(), :refresh, config.refresh_interval)
         {:noreply, config}
     end
   end

lib/last_fm/supervisor.ex

@@ -1,28 +1,19 @@
 defmodule LastFm.Supervisor do
   use Supervisor
 
-  def start_link(init_arg) do
-    Supervisor.start_link(__MODULE__, init_arg, name: __MODULE__)
+  def start_link(config) do
+    Supervisor.start_link(__MODULE__, config, name: __MODULE__)
   end
 
   @impl true
-  def init(_opts) do
+  def init(config) do
     :ok = LastFm.Feed.create_table!()
 
     children = [
       {Phoenix.PubSub, name: LastFm.PubSub},
-      {LastFm.Refresh, %{api: api(), user: "cloud8421", api_key: api_key()}}
+      {LastFm.Refresh, config}
     ]
 
     Supervisor.init(children, strategy: :one_for_one)
   end
-
-  defp api_key do
-    Application.get_env(:music_library, LastFm, [])
-    |> Keyword.get(:api_key)
-  end
-
-  defp api do
-    Application.get_env(:music_library, :last_fm, LastFm.APIImpl)
-  end
 end

lib/music_library/application.ex

@@ -15,7 +15,7 @@ defmodule MusicLibrary.Application do
        repos: Application.fetch_env!(:music_library, :ecto_repos), skip: skip_migrations?()},
       {DNSCluster, query: Application.get_env(:music_library, :dns_cluster_query) || :ignore},
       {Phoenix.PubSub, name: MusicLibrary.PubSub},
-      LastFm.Supervisor,
+      {LastFm.Supervisor, last_fm_config()},
       # Start a worker by calling: MusicLibrary.Worker.start_link(arg)
       # {MusicLibrary.Worker, arg},
       # Start to serve requests, typically the last entry
@@ -40,4 +40,8 @@ defmodule MusicLibrary.Application do
     # By default, sqlite migrations are run when using a release
     System.get_env("RELEASE_NAME") != nil
   end
+
+  defp last_fm_config do
+    Application.get_env(:music_library, LastFm)
+  end
 end