update metadata tags when sorting

internal/metadata/vobis.go

@@ -0,0 +1,57 @@
+package metadata
+
+import (
+	"log/slog"
+	"strconv"
+
+	"github.com/go-flac/flacvorbis/v2"
+	"github.com/go-flac/go-flac/v2"
+)
+
+func updateFlacMetadata(m Metadata, input, output string) error {
+	f, err := flac.ParseFile(input)
+	if err != nil {
+		return err
+	}
+
+	vorbisMeta := createVorbisMetaBlock(m)
+	meta := vorbisMeta.Marshal()
+
+	replaced := false
+	for i, block := range f.Meta {
+		if block.Type == flac.VorbisComment {
+			f.Meta[i] = &meta
+			replaced = true
+			break
+		}
+	}
+
+	if !replaced {
+		f.Meta = append(f.Meta, &meta)
+	}
+
+	return f.Save(output)
+}
+
+func createVorbisMetaBlock(m Metadata) flacvorbis.MetaDataBlockVorbisComment {
+	vorbisMeta := flacvorbis.New()
+
+	vorbisMeta.Add(flacvorbis.FIELD_TITLE, m.Title)
+	vorbisMeta.Add(flacvorbis.FIELD_ALBUM, m.Album)
+	vorbisMeta.Add("COMMENT", m.Comment)
+	vorbisMeta.Add("TRACKNUMBER", strconv.Itoa(m.Track))
+	vorbisMeta.Add("TOTALTRACKS", strconv.Itoa(m.TotalTracks))
+	vorbisMeta.Add("DISCNUMBER", strconv.Itoa(m.Disc))
+	vorbisMeta.Add("TOTALDISCS", strconv.Itoa(m.TotalDiscs))
+
+	for _, artist := range m.Artist {
+		vorbisMeta.Add(flacvorbis.FIELD_ARTIST, artist)
+		slog.Debug("Added ARTIST filed to metadata", "artist", artist)
+	}
+
+	for _, albumArtist := range m.AlbumArtist {
+		vorbisMeta.Add("ALBUMARTIST", albumArtist)
+	}
+
+	return *vorbisMeta
+}