Normalize top artist and top album counts

- Make sure joins don't discard tracks
- Make sure we group by names as MB ids can be empty

test/music_library/scrobble_activity_test.exs

@@ -271,6 +271,132 @@ defmodule MusicLibrary.ScrobbleActivityTest do
     end
   end
 
+  describe "get_top_artists/1" do
+    test "counts tracks with missing artist_infos records" do
+      artist_mbid = Ecto.UUID.generate()
+
+      # Create an artist_info record for the known musicbrainz_id
+      MusicLibrary.Repo.insert!(%MusicLibrary.Artists.ArtistInfo{
+        id: artist_mbid,
+        musicbrainz_data: %{"name" => "Thin Lizzy"}
+      })
+
+      now = System.system_time(:second)
+
+      # Two tracks with a matching artist_infos record
+      track_fixture(%{
+        artist_name: "Thin Lizzy",
+        artist_musicbrainz_id: artist_mbid,
+        title: "The Boys Are Back in Town",
+        scrobbled_at_uts: now - 100
+      })
+
+      track_fixture(%{
+        artist_name: "Thin Lizzy",
+        artist_musicbrainz_id: artist_mbid,
+        title: "Jailbreak",
+        scrobbled_at_uts: now - 200
+      })
+
+      # One track with an empty musicbrainz_id (no matching artist_infos)
+      track_fixture(%{
+        artist_name: "Thin Lizzy",
+        artist_musicbrainz_id: "",
+        title: "Rosalie / Cowgirl's Song",
+        scrobbled_at_uts: now - 300
+      })
+
+      results = ScrobbleActivity.get_top_artists(limit: 10)
+
+      # All 3 tracks should be counted as a single artist entry
+      assert [thin_lizzy] = Enum.filter(results, fn r -> r.name == "Thin Lizzy" end)
+      assert thin_lizzy.play_count == 3
+      # MAX picks the real musicbrainz_id over the empty string
+      assert thin_lizzy.musicbrainz_id == artist_mbid
+    end
+
+    test "returns image_hash from artist_infos when available" do
+      artist_mbid = Ecto.UUID.generate()
+
+      MusicLibrary.Repo.insert!(%MusicLibrary.Artists.ArtistInfo{
+        id: artist_mbid,
+        musicbrainz_data: %{"name" => "Test Artist"},
+        image_data_hash: "abc123"
+      })
+
+      track_fixture(%{
+        artist_name: "Test Artist",
+        artist_musicbrainz_id: artist_mbid,
+        title: "Track 1",
+        scrobbled_at_uts: System.system_time(:second) - 100
+      })
+
+      [result] = ScrobbleActivity.get_top_artists(limit: 10)
+
+      assert result.image_hash == "abc123"
+    end
+
+    test "returns nil image_hash for tracks without artist_infos" do
+      track_fixture(%{
+        artist_name: "Unknown Artist",
+        artist_musicbrainz_id: "",
+        title: "Track 1",
+        scrobbled_at_uts: System.system_time(:second) - 100
+      })
+
+      [result] = ScrobbleActivity.get_top_artists(limit: 10)
+
+      assert result.image_hash == nil
+    end
+  end
+
+  describe "get_top_artists_by_days/2" do
+    test "counts tracks with missing artist_infos records within date range" do
+      artist_mbid = Ecto.UUID.generate()
+
+      MusicLibrary.Repo.insert!(%MusicLibrary.Artists.ArtistInfo{
+        id: artist_mbid,
+        musicbrainz_data: %{"name" => "Thin Lizzy"}
+      })
+
+      now = DateTime.utc_now()
+      now_unix = DateTime.to_unix(now)
+
+      # Two tracks with matching artist_infos
+      track_fixture(%{
+        artist_name: "Thin Lizzy",
+        artist_musicbrainz_id: artist_mbid,
+        title: "The Boys Are Back in Town",
+        scrobbled_at_uts: now_unix - 100
+      })
+
+      track_fixture(%{
+        artist_name: "Thin Lizzy",
+        artist_musicbrainz_id: artist_mbid,
+        title: "Jailbreak",
+        scrobbled_at_uts: now_unix - 200
+      })
+
+      # One track with empty musicbrainz_id
+      track_fixture(%{
+        artist_name: "Thin Lizzy",
+        artist_musicbrainz_id: "",
+        title: "Rosalie / Cowgirl's Song",
+        scrobbled_at_uts: now_unix - 300
+      })
+
+      results =
+        ScrobbleActivity.get_top_artists_by_days(7,
+          limit: 10,
+          current_time: now,
+          timezone: "Etc/UTC"
+        )
+
+      assert [thin_lizzy] = Enum.filter(results, fn r -> r.name == "Thin Lizzy" end)
+      assert thin_lizzy.play_count == 3
+    end
+  end
+
   describe "integration with existing functions" do
     test "scrobble_count returns correct count" do
       initial_count = ScrobbleActivity.scrobble_count()