fetching from object not from source

internal/cli/shell.go

@@ -100,11 +100,7 @@ func interpretCommand(command string, store musicObjectStore) (musicObjectStore,
 
 		current := currentMusicObjects[index]
 
-		if len(current.GetSources()) <= 0 {
-			return store, errors.New("selected object has no sources to download")
-		}
-
-		currentMusicObjects, err = plugin.FetchList(current.GetSources()[0])
+		currentMusicObjects, err = plugin.FetchList(current)
 		if err != nil {
 			return store, err
 		}

internal/plugin/interface.go

@@ -99,7 +99,7 @@ func compileSource(source data.Source) (data.Source, error) {
 	return source, errors.New("couldn't find corresponding object source on " + sourceType.Name + " for " + source.Url)
 }
 
-func Fetch(source data.Source) (data.MusicObject, error) {
+func FetchSource(source data.Source) (data.MusicObject, error) {
 	// the fetch function without the post processing of the music objects
 	source, err := compileSource(source)
 	if err != nil {
@@ -147,10 +147,29 @@ func Fetch(source data.Source) (data.MusicObject, error) {
 	return nil, nil
 }
 
-func FetchList(source data.Source) ([]data.MusicObject, error) {
+func Fetch(musicObject data.MusicObject) (data.MusicObject, error) {
+	sources := musicObject.GetSources()
+
+	if len(sources) <= 0 {
+		return musicObject, errors.New("didn't find a source for object")
+	}
+
+	for _, source := range sources {
+		newMusicObject, err := FetchSource(source)
+		if err != nil {
+			return musicObject, err
+		}
+
+		musicObject = musicObject.Merge(newMusicObject)
+	}
+
+	return musicObject, nil
+}
+
+func FetchList(musicObject data.MusicObject) ([]data.MusicObject, error) {
 	res := []data.MusicObject{}
 
-	musicObject, err := Fetch(source)
+	musicObject, err := Fetch(musicObject)
 	if err != nil {
 		return res, err
 	}