update metadata tags when sorting

internal/metadata/metadata.go

@@ -0,0 +1,78 @@
+package metadata
+
+import (
+	"fmt"
+	"log/slog"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/dhowden/tag"
+)
+
+type Metadata struct {
+	Title       string
+	Artist      []string
+	Album       string
+	AlbumArtist []string
+	Track       int
+	TotalTracks int
+	Disc        int
+	TotalDiscs  int
+	Comment     string
+}
+
+func ReadAudioTags(filePath string) (*Metadata, error) {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open file: %w", err)
+	}
+	defer f.Close()
+
+	m, err := tag.ReadFrom(f)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read tags: %w", err)
+	}
+
+	track, totalTracks := m.Track()
+	disc, totalDiscs := m.Disc()
+
+	info := &Metadata{
+		Title:       m.Title(),
+		Artist:      parseSeperatedTag(m.Artist()),
+		Album:       m.Album(),
+		AlbumArtist: parseSeperatedTag(m.AlbumArtist()),
+		Track:       track,
+		TotalTracks: totalTracks,
+		Disc:        disc,
+		TotalDiscs:  totalDiscs,
+		Comment:     m.Comment(),
+	}
+
+	return info, nil
+}
+
+func parseSeperatedTag(s string) []string {
+	parsed := make([]string, 0)
+
+	for element := range strings.SplitSeq(s, ";") {
+		parsed = append(parsed, strings.TrimSpace(element))
+	}
+
+	return parsed
+}
+
+func UpdateMetadata(src, dst string, m Metadata) error {
+
+	ext := strings.ToLower(filepath.Ext(src))
+
+	switch {
+	case ext == ".flac":
+		return updateFlacMetadata(m, src, dst)
+	default:
+		slog.Warn("Unsupported format for updating metadata")
+	}
+
+	return nil
+
+}