add trackiterator

backend/librarymanager.go

@@ -8,6 +8,10 @@ type AlbumIterator interface {
 	Next() *subsonic.AlbumID3
 }
 
+type TrackIterator interface {
+	Next() *subsonic.Child
+}
+
 type LibraryManager struct {
 	PreCacheCoverFn func(coverID string)
 

backend/trackiterator.go

@@ -0,0 +1,42 @@
+package backend
+
+import "github.com/dweymouth/go-subsonic/subsonic"
+
+type allTracksIterator struct {
+	albumIter   AlbumIterator
+	curAlbum    *subsonic.AlbumID3
+	curTrackIdx int
+	done        bool
+}
+
+func (l *LibraryManager) AllTracksIterator() TrackIterator {
+	return &allTracksIterator{
+		albumIter: l.AlbumsIter(AlbumSortRecentlyAdded),
+	}
+}
+
+func (a *allTracksIterator) Next() *subsonic.Child {
+	if a.done {
+		return nil
+	}
+
+	// fetch next album
+	if a.curAlbum == nil || a.curTrackIdx >= len(a.curAlbum.Song) {
+		a.curAlbum = a.albumIter.Next()
+		if a.curAlbum == nil {
+			a.done = true
+			return nil
+		}
+		a.curTrackIdx = 0
+
+		if len(a.curAlbum.Song) == 0 {
+			// in the unlikely case of an album with zero tracks,
+			// just call recursively to move to next album
+			return a.Next()
+		}
+	}
+
+	tr := a.curAlbum.Song[a.curTrackIdx]
+	a.curTrackIdx += 1
+	return tr
+}