feat(song): add ID3v2 tags

internal/deezer/tag.go

@@ -0,0 +1,70 @@
+package deezer
+
+import (
+	"fmt"
+	"path"
+	"strconv"
+	"strings"
+
+	"github.com/bogem/id3v2/v2"
+)
+
+func AddTags(album *Album, song *Song, pathFile string) error {
+	ext := path.Ext(pathFile)
+	if ext == ".mp3" {
+		tag, err := id3v2.Open(pathFile, id3v2.Options{Parse: true})
+		if err != nil {
+			return err
+		}
+		defer tag.Close()
+
+		var year string
+		duration, _ := strconv.Atoi(song.Duration)
+		dateParts := strings.Split(album.Data.PhysicalReleaseDate, "-")
+		if len(dateParts) == 3 {
+			year = dateParts[0]
+		}
+
+		addTag(tag, "TALB", album.Data.Name)
+		addTag(tag, "TPE2", album.Data.Artist)
+		addTag(tag, "TPUB", album.Data.Label)
+		addTag(tag, "TDOR", album.Data.OriginalReleaseDate)
+		addTag(tag, "COMM", album.Data.ProducerLine)
+		if year != "" {
+			addTag(tag, "TYER", year)
+		}
+
+		addTag(tag, "TIT2", song.Title)
+		addTag(tag, "TPE1", strings.Join(song.Contributors.MainArtists, " / "))
+		addTag(tag, "TCOM", strings.Join(song.Contributors.Composers, " / "))
+		addTag(tag, "TEXT", strings.Join(song.Contributors.Authors, " / "))
+		addTag(tag, "TRCK", song.TrackNumber)
+		if duration > 0 {
+			addTag(tag, "TLEN", fmt.Sprintf("%d", duration*1000))
+		}
+		addTXXXTag(tag, "GAIN", song.Gain)
+		addTXXXTag(tag, "ISRC", song.ISRC)
+		addTXXXTag(tag, "Explicit lyrics", song.ExplicitLyrics)
+
+		return tag.Save()
+	}
+
+	return nil
+}
+
+func addTag(tag *id3v2.Tag, name, value string) {
+	if value != "" {
+		tag.AddTextFrame(name, tag.DefaultEncoding(), value)
+	}
+}
+
+func addTXXXTag(tag *id3v2.Tag, description, value string) {
+	if value != "" {
+		udf := id3v2.UserDefinedTextFrame{
+			Encoding:    tag.DefaultEncoding(),
+			Description: description,
+			Value:       value,
+		}
+		tag.AddUserDefinedTextFrame(udf)
+	}
+}