feat(agents): support multiple languages for Last.fm and Deezer metadata (#4952)

* feat(lastfm): support multiple languages for album and artist info retrieval

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

* fix(lastfm): improve content validation for album and artist descriptions

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

* refactor(lastfm): remove single language test and clarify languages field in configuration

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

* feat(deezer): support multiple languages for artist bio retrieval

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

* refactor(lastfm): rename ignoredBiographies to ignoredContent for clarity

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

---------

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

conf/configuration.go

@@ -175,6 +175,9 @@ type lastfmOptions struct {
 	Secret                  string
 	Language                string
 	ScrobbleFirstArtistOnly bool
+
+	// Computed values
+	Languages []string // Computed from Language, split by comma
 }
 
 type spotifyOptions struct {
@@ -185,6 +188,9 @@ type spotifyOptions struct {
 type deezerOptions struct {
 	Enabled  bool
 	Language string
+
+	// Computed values
+	Languages []string // Computed from Language, split by comma
 }
 
 type listenBrainzOptions struct {
@@ -374,6 +380,12 @@ func Load(noConfigDump bool) {
 	Server.PID.Album = cmp.Or(Server.PID.Album, consts.DefaultAlbumPID)
 	Server.PID.Track = cmp.Or(Server.PID.Track, consts.DefaultTrackPID)
 
+	// Parse LastFM.Language into Languages slice (comma-separated, with fallback to DefaultInfoLanguage)
+	Server.LastFM.Languages = parseLanguages(Server.LastFM.Language)
+
+	// Parse Deezer.Language into Languages slice (comma-separated, with fallback to DefaultInfoLanguage)
+	Server.Deezer.Languages = parseLanguages(Server.Deezer.Language)
+
 	logDeprecatedOptions("Scanner.GenreSeparators", "")
 	logDeprecatedOptions("Scanner.GroupAlbumReleases", "")
 	logDeprecatedOptions("DevEnableBufferedScrobble", "") // Deprecated: Buffered scrobbling is now always enabled and this option is ignored
@@ -462,6 +474,22 @@ func validatePlaylistsPath() error {
 	return nil
 }
 
+// parseLanguages parses a comma-separated language string into a slice.
+// It trims whitespace from each entry and ensures at least [DefaultInfoLanguage] is returned.
+func parseLanguages(lang string) []string {
+	var languages []string
+	for _, l := range strings.Split(lang, ",") {
+		l = strings.TrimSpace(l)
+		if l != "" {
+			languages = append(languages, l)
+		}
+	}
+	if len(languages) == 0 {
+		return []string{consts.DefaultInfoLanguage}
+	}
+	return languages
+}
+
 func validatePurgeMissingOption() error {
 	allowedValues := []string{consts.PurgeMissingNever, consts.PurgeMissingAlways, consts.PurgeMissingFull}
 	valid := false
@@ -618,14 +646,14 @@ func setViperDefaults() {
 	viper.SetDefault("subsonic.legacyclients", "DSub,SubMusic")
 	viper.SetDefault("agents", "lastfm,spotify,deezer")
 	viper.SetDefault("lastfm.enabled", true)
-	viper.SetDefault("lastfm.language", "en")
+	viper.SetDefault("lastfm.language", consts.DefaultInfoLanguage)
 	viper.SetDefault("lastfm.apikey", "")
 	viper.SetDefault("lastfm.secret", "")
 	viper.SetDefault("lastfm.scrobblefirstartistonly", false)
 	viper.SetDefault("spotify.id", "")
 	viper.SetDefault("spotify.secret", "")
 	viper.SetDefault("deezer.enabled", true)
-	viper.SetDefault("deezer.language", "en")
+	viper.SetDefault("deezer.language", consts.DefaultInfoLanguage)
 	viper.SetDefault("listenbrainz.enabled", true)
 	viper.SetDefault("listenbrainz.baseurl", "https://api.listenbrainz.org/1/")
 	viper.SetDefault("enablescrobblehistory", true)

conf/configuration_test.go

@@ -26,6 +26,32 @@ var _ = Describe("Configuration", func() {
 		conf.ResetConf()
 	})
 
+	Describe("ParseLanguages", func() {
+		It("parses single language", func() {
+			Expect(conf.ParseLanguages("en")).To(Equal([]string{"en"}))
+		})
+
+		It("parses multiple comma-separated languages", func() {
+			Expect(conf.ParseLanguages("pt,en")).To(Equal([]string{"pt", "en"}))
+		})
+
+		It("trims whitespace from languages", func() {
+			Expect(conf.ParseLanguages(" pt , en ")).To(Equal([]string{"pt", "en"}))
+		})
+
+		It("returns default 'en' when empty", func() {
+			Expect(conf.ParseLanguages("")).To(Equal([]string{"en"}))
+		})
+
+		It("returns default 'en' when only whitespace", func() {
+			Expect(conf.ParseLanguages("   ")).To(Equal([]string{"en"}))
+		})
+
+		It("handles multiple languages with various spacing", func() {
+			Expect(conf.ParseLanguages("ja, pt, en")).To(Equal([]string{"ja", "pt", "en"}))
+		})
+	})
+
 	DescribeTable("should load configuration from",
 		func(format string) {
 			filename := filepath.Join("testdata", "cfg."+format)

conf/export_test.go

@@ -5,3 +5,5 @@ func ResetConf() {
 }
 
 var SetViperDefaults = setViperDefaults
+
+var ParseLanguages = parseLanguages