db: Preserve the current track when adding tracks

We have to be careful not to check track positions against playlists
where current == -1, because this could drastically slow down adding new
tracks because SQLite would need to find the position for every track

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

db/playlist.py

@@ -57,6 +57,9 @@ class Playlist(GObject.GObject):
                           f"WHERE trackid=?", [ track.rowid ])
         return cur.fetchone()[1] - 1
 
+    def track_adjusts_current(self, track):
+        return self.current > -1 and self.get_track_index(track) <= self.current
+
     def add_track(self, track):
         self.emit("track-added", track)
 
@@ -132,7 +135,9 @@ class Playlist(GObject.GObject):
     def refreshed(self): pass
 
     @GObject.Signal(arg_types=(GObject.TYPE_PYOBJECT,))
-    def track_added(self, track): pass
+    def track_added(self, track):
+        if self.track_adjusts_current(track):
+            self.current += 1
 
     @GObject.Signal(arg_types=(GObject.TYPE_PYOBJECT,))
     def track_removed(self, track): pass

db/test_playlist.py

@@ -40,6 +40,32 @@ class TestPlaylist(unittest.TestCase):
         with self.assertRaises(NotImplementedError):
             plist.delete()
 
+    def test_add_track(self):
+        plist = db.user.Table.find("Test Playlist")
+        track1 = db.make_fake_track(1, 1, "Track 1", "/a/b/c/1.ogg")
+        track2 = db.make_fake_track(2, 2, "Track 2", "/a/b/c/2.ogg")
+        track3 = db.make_fake_track(3, 3, "Track 3", "/a/b/c/3.ogg")
+        plist.sort = [ "tracks.number ASC" ]
+
+        plist.add_track(track2)
+        self.assertEqual(plist.get_track(0), track2)
+        self.assertEqual(plist.current, -1)
+        self.assertFalse(plist.track_adjusts_current(track2))
+
+        plist.current = 0
+        self.assertTrue(plist.track_adjusts_current(track2))
+
+        plist.add_track(track1)
+        self.assertEqual(plist.get_track(0), track1)
+        self.assertEqual(plist.get_track(1), track2)
+        self.assertEqual(plist.current, 1)
+
+        plist.add_track(track3)
+        self.assertEqual(plist.get_track(0), track1)
+        self.assertEqual(plist.get_track(1), track2)
+        self.assertEqual(plist.get_track(2), track3)
+        self.assertEqual(plist.current, 1)
+
     def test_current(self):
         plist = db.user.Table.find("Test Playlist")
         self.assertEqual(plist.get_property("current"), -1)