Move collected artist IDs query to Collection context

Closes #112

lib/music_library/artists.ex

@@ -3,7 +3,8 @@ defmodule MusicLibrary.Artists do
 
   alias MusicLibrary.Artists.ArtistInfo
   alias MusicLibrary.Assets
-  alias MusicLibrary.Records.{ArtistRecord, Record}
+  alias MusicLibrary.Collection
+  alias MusicLibrary.Records.ArtistRecord
   alias MusicLibrary.{Repo, Worker}
 
   @spec get_artist!(String.t()) :: map()
@@ -21,7 +22,7 @@ defmodule MusicLibrary.Artists do
   def get_similar_artists(artist) do
     case LastFm.get_similar_artists(artist.musicbrainz_id, artist.name) do
       {:ok, artists} ->
-        collected_artist_ids = get_collected_artist_ids()
+        collected_artist_ids = Collection.collected_artist_ids()
 
         {:ok,
          Enum.filter(artists, fn a ->
@@ -309,18 +310,6 @@ defmodule MusicLibrary.Artists do
     |> Repo.update()
   end
 
-  defp get_collected_artist_ids do
-    q =
-      from ar in ArtistRecord,
-        join: r in Record,
-        on: r.id == ar.record_id,
-        where: not is_nil(r.purchased_at),
-        distinct: true,
-        select: ar.musicbrainz_id
-
-    q |> Repo.all() |> MapSet.new()
-  end
-
   defp enqueue_worker(worker, params) do
     params |> worker.new(meta: %{}) |> Oban.insert()
   end

lib/music_library/collection.ex

@@ -3,7 +3,7 @@ defmodule MusicLibrary.Collection do
   import MusicLibrary.Records, only: [order_alphabetically: 0]
 
   alias MusicLibrary.Records
-  alias MusicLibrary.Records.{Record, RecordRelease, SearchIndex}
+  alias MusicLibrary.Records.{ArtistRecord, Record, RecordRelease, SearchIndex}
   alias MusicLibrary.Repo
 
   @excluded_genres Application.compile_env!(:music_library, :excluded_genres)
@@ -164,6 +164,19 @@ defmodule MusicLibrary.Collection do
       select: %{record_id: rr.record_id, cover_hash: rr.cover_hash, release_id: rr.release_id}
   end
 
+  @spec collected_artist_ids() :: MapSet.t(String.t())
+  def collected_artist_ids do
+    from(ar in ArtistRecord,
+      join: r in Record,
+      on: r.id == ar.record_id,
+      where: not is_nil(r.purchased_at),
+      distinct: true,
+      select: ar.musicbrainz_id
+    )
+    |> Repo.all()
+    |> MapSet.new()
+  end
+
   defp base_search do
     from r in SearchIndex,
       where: not is_nil(r.purchased_at)