For Song struct a method SetFrom was added.

internal/radio/song.go

@@ -16,6 +16,17 @@ type Song struct {
 	StartAt      time.Time
 }
 
+func (s *Song) SetFrom(os *Song) {
+	s.mutex.Lock()
+	s.Artist = os.Artist
+	s.Title = os.Title
+	s.Duration = os.Duration
+	s.Listeners = os.Listeners
+	s.MaxListeners = os.MaxListeners
+	s.StartAt = os.StartAt
+	s.mutex.Unlock()
+}
+
 func (s *Song) UpdateMaxListeners(listeners int64) {
 	s.mutex.Lock()
 	if listeners > s.MaxListeners {