feat(scanner): enhance album artist mapping logic for better display name handling

Signed-off-by: Deluan <deluan@navidrome.org>

model/metadata/map_participants.go

@@ -224,13 +224,38 @@ func (md Metadata) mapDisplayArtist() string {
 }
 
 func (md Metadata) mapDisplayAlbumArtist(mf model.MediaFile) string {
+	// 1. Check for explicit album artist tags first
+	albumArtistDisplay := md.mapDisplayName(model.TagAlbumArtist, model.TagAlbumArtists)
+	if albumArtistDisplay != "" {
+		return albumArtistDisplay
+	}
+
+	// 2. No explicit album artist, check for track artist tags
+	artistTag := model.TagTrackArtist
+	artistsTag := model.TagTrackArtists
+	hasMultiValuedArtistTag := len(md.tags[artistTag]) > 1 || len(md.tags[artistsTag]) > 1
+	hasSingleValuedArtistTag := len(md.tags[artistTag]) == 1 || len(md.tags[artistsTag]) == 1
+
+	if hasMultiValuedArtistTag {
+		// Special case from tests: Use only the first artist if ARTIST/ARTISTS tag is multi-valued
+		if len(md.tags[artistTag]) > 1 {
+			return md.tags[artistTag][0]
+		}
+		// We know artistsTag must have > 1 here
+		return md.tags[artistsTag][0]
+	}
+	// If execution reaches here, hasMultiValuedArtistTag is false
+	if hasSingleValuedArtistTag {
+		// For single artist values (including those with separators like ';'), use the artist display name
+		return md.mapDisplayArtist()
+	}
+
+	// 3. Neither album artist nor track artist tags found. Fallback logic:
 	fallbackName := consts.UnknownArtist
 	if md.Bool(model.TagCompilation) {
 		fallbackName = consts.VariousArtists
 	}
-	return cmp.Or(
-		md.mapDisplayName(model.TagAlbumArtist, model.TagAlbumArtists),
-		mf.Participants.First(model.RoleAlbumArtist).Name,
-		fallbackName,
-	)
+
+	// Use the name from the first participant found for RoleAlbumArtist, or the default fallback
+	return cmp.Or(mf.Participants.First(model.RoleAlbumArtist).Name, fallbackName)
 }

model/metadata/map_participants_test.go

@@ -370,6 +370,49 @@ var _ = Describe("Participants", func() {
 				Expect(artist1.MbzArtistID).To(Equal(mbid2))
 			})
 		})
+
+		Context("Single-valued ARTIST tag with semicolon, no ARTISTS tags", func() {
+			BeforeEach(func() {
+				mf = toMediaFile(model.RawTags{
+					"ARTIST": {"hey; ho"},
+				})
+			})
+
+			It("should use the full string as display name", func() {
+				Expect(mf.Artist).To(Equal("hey; ho"))
+			})
+
+			It("should split the artist by semicolon", func() {
+				participants := mf.Participants
+				Expect(participants).To(SatisfyAll(
+					HaveKeyWithValue(model.RoleArtist, HaveLen(2)),
+				))
+
+				By("adding the first artist to the participants")
+				artist0 := participants[model.RoleArtist][0]
+				Expect(artist0.ID).ToNot(BeEmpty())
+				Expect(artist0.Name).To(Equal("hey"))
+				Expect(artist0.OrderArtistName).To(Equal("hey"))
+
+				By("adding the second artist to the participants")
+				artist1 := participants[model.RoleArtist][1]
+				Expect(artist1.ID).ToNot(BeEmpty())
+				Expect(artist1.Name).To(Equal("ho"))
+				Expect(artist1.OrderArtistName).To(Equal("ho"))
+			})
+
+			It("should use the full artist name as albumArtist when no ALBUMARTIST is provided", func() {
+				Expect(mf.AlbumArtist).To(Equal("hey; ho"))
+
+				participants := mf.Participants
+				Expect(participants).To(SatisfyAll(
+					HaveKeyWithValue(model.RoleAlbumArtist, HaveLen(2)),
+				))
+
+				albumArtist := participants[model.RoleAlbumArtist][0]
+				Expect(albumArtist.Name).To(Equal("hey"))
+			})
+		})
 	})
 
 	Describe("ALBUMARTIST(S) tags", func() {