Move BackfillScrobbledTracks worker under MusicLibrary namespace

lib/last_fm.ex

@@ -3,8 +3,7 @@ defmodule LastFm do
   Last.fm API facade for scrobbling and listening history.
   """
 
-  alias LastFm.{API, Scrobble, Track, Worker}
-  alias MusicLibrary.{BackgroundRepo, Repo}
+  alias LastFm.{API, Scrobble, Track}
 
   @spec get_tracks(keyword()) :: {:ok, [Track.t()]} | {:error, term()}
   def get_tracks(opts) do
@@ -12,20 +11,6 @@ defmodule LastFm do
     API.get_recent_tracks(opts, last_fm_config)
   end
 
-  @spec lowest_scrobbled_at_uts() :: integer() | nil
-  def lowest_scrobbled_at_uts do
-    Repo.aggregate(Track, :min, :scrobbled_at_uts)
-  end
-
-  @spec backfill_scrobbled_tracks() :: {:ok, Oban.Job.t()} | {:error, Ecto.Changeset.t()}
-  def backfill_scrobbled_tracks do
-    to_uts = lowest_scrobbled_at_uts()
-
-    %{"to_uts" => to_uts}
-    |> Worker.BackfillScrobbledTracks.new()
-    |> BackgroundRepo.insert()
-  end
-
   @spec get_artist_info(String.t(), String.t()) :: {:ok, LastFm.Artist.t()} | {:error, term()}
   def get_artist_info(musicbrainz_id, name) do
     last_fm_config = last_fm_config()

lib/music_library/listening_stats.ex

@@ -13,12 +13,14 @@ defmodule MusicLibrary.ListeningStats do
 
   alias MusicLibrary.{
     Artists,
+    BackgroundRepo,
     Collection,
     ListeningStats.Refresh,
     Records.ArtistRecord,
     Records.Record,
     Repo,
-    Wishlist
+    Wishlist,
+    Worker
   }
 
   @pagination Application.compile_env!(:music_library, :pagination)
@@ -79,6 +81,20 @@ defmodule MusicLibrary.ListeningStats do
     Refresh.refresh()
   end
 
+  @spec lowest_scrobbled_at_uts() :: integer() | nil
+  def lowest_scrobbled_at_uts do
+    Repo.aggregate(Track, :min, :scrobbled_at_uts)
+  end
+
+  @spec backfill_scrobbled_tracks() :: {:ok, Oban.Job.t()} | {:error, Ecto.Changeset.t()}
+  def backfill_scrobbled_tracks do
+    to_uts = lowest_scrobbled_at_uts()
+
+    %{"to_uts" => to_uts}
+    |> Worker.BackfillScrobbledTracks.new()
+    |> BackgroundRepo.insert()
+  end
+
   @spec artist_play_count(String.t()) :: non_neg_integer()
   def artist_play_count(artist_musicbrainz_id) do
     from(t in Track,

lib/music_library/worker/backfill_scrobbled_tracks.ex

@@ -1,19 +1,23 @@
-defmodule LastFm.Worker.BackfillScrobbledTracks do
+defmodule MusicLibrary.Worker.BackfillScrobbledTracks do
+  @moduledoc """
+  Oban worker that backfills scrobbled tracks from Last.fm in batches.
+
+  Self-chaining: after importing a full batch, enqueues itself with the
+  next `to_uts` timestamp to continue backfilling.
+  """
+
   use Oban.Worker, queue: :heavy_writes, max_attempts: 3
 
-  alias MusicLibrary.BackgroundRepo
+  alias MusicLibrary.{BackgroundRepo, ListeningStats}
 
   @backfill_delay 1
   @batch_size 200
 
   @impl Oban.Worker
   def perform(%{args: %{"to_uts" => to_uts}}) do
-    # importing is an all or nothing operation, which means that we can
-    # use the returning count to determine if we reached the end of the backfilling
-    # process.
     case LastFm.Import.batch(to_uts: to_uts, limit: @batch_size) do
       {:ok, @batch_size} ->
-        next_to_uts = LastFm.lowest_scrobbled_at_uts()
+        next_to_uts = ListeningStats.lowest_scrobbled_at_uts()
 
         %{"to_uts" => next_to_uts}
         |> new(schedule_in: @backfill_delay)