fix #78 #106: app crash due to imcompatible ncm metadata json

algo/ncm/meta.go

@@ -1,6 +1,7 @@
 package ncm
 
 import (
+	"go.uber.org/zap"
 	"strings"
 
 	"unlock-music.dev/cli/algo/common"
@@ -17,9 +18,11 @@ type ncmMeta interface {
 }
 
 type ncmMetaMusic struct {
+	logger *zap.Logger
+
 	Format        string        `json:"format"`
 	MusicName     string        `json:"musicName"`
-	Artist        [][]interface{} `json:"artist"`
+	Artist        interface{}   `json:"artist"`
 	Album         string        `json:"album"`
 	AlbumPicDocID interface{}   `json:"albumPicDocId"`
 	AlbumPic      string        `json:"albumPic"`
@@ -30,20 +33,34 @@ type ncmMetaMusic struct {
 	TransNames    []interface{} `json:"transNames"`
 }
 
+func newNcmMetaMusic(logger *zap.Logger) *ncmMetaMusic {
+	ncm := new(ncmMetaMusic)
+	ncm.logger = logger.With(zap.String("module", "ncmMetaMusic"))
+	return ncm
+}
+
 func (m *ncmMetaMusic) GetAlbumImageURL() string {
 	return m.AlbumPic
 }
 
-func (m *ncmMetaMusic) GetArtists() (artists []string) {
-	for _, artist := range m.Artist {
-		for _, item := range artist {
-			name, ok := item.(string)
-			if ok {
+func (m *ncmMetaMusic) GetArtists() []string {
+	m.logger.Debug("ncm artists", zap.Any("artists", m.Artist))
+
+	var artists []string = nil
+	if jsonArtists, ok := m.Artist.([][]string); ok {
+		for _, artist := range jsonArtists {
+			for _, name := range artist {
 				artists = append(artists, name)
 			}
 		}
+	} else if artist, ok := m.Artist.(string); ok {
+		// #78: artist is a string type.
+		// https://git.unlock-music.dev/um/cli/issues/78
+		artists = []string{artist}
+	} else {
+		m.logger.Warn("unexpected artist type", zap.Any("artists", m.Artist))
 	}
-	return
+	return artists
 }
 
 func (m *ncmMetaMusic) GetTitle() string {

algo/ncm/ncm.go

@@ -8,6 +8,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"go.uber.org/zap"
 	"io"
 	"net/http"
 	"strings"
@@ -30,10 +31,11 @@ var (
 )
 
 func NewDecoder(p *common.DecoderParams) common.Decoder {
-	return &Decoder{rd: p.Reader}
+	return &Decoder{rd: p.Reader, logger: p.Logger.With(zap.String("module", "ncm"))}
 }
 
 type Decoder struct {
+	logger *zap.Logger
 	rd     io.ReadSeeker // rd is the original file reader
 
 	offset int
@@ -74,7 +76,7 @@ func (d *Decoder) Validate() error {
 	}
 
 	if err := d.parseMeta(); err != nil {
-		return fmt.Errorf("parse meta failed: %w", err)
+		return fmt.Errorf("parse meta failed: %w (raw json=%s)", err, string(d.metaRaw))
 	}
 
 	d.cipher = newNcmCipher(keyData)
@@ -181,7 +183,7 @@ func (d *Decoder) readCoverData() error {
 func (d *Decoder) parseMeta() error {
 	switch d.metaType {
 	case "music":
-		d.meta = new(ncmMetaMusic)
+		d.meta = newNcmMetaMusic(d.logger)
 		return json.Unmarshal(d.metaRaw, d.meta)
 	case "dj":
 		d.meta = new(ncmMetaDJ)