trackdb: Add lookup methods for track ids

Playlists will want to use this when reading saved state to figure out
what tracks they hold.

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

test_trackdb.py

@@ -49,6 +49,12 @@ class TestTrackDB(unittest.TestCase):
         lib = trackdb.add_path(test_tracks)
         self.assertEqual(trackdb.get_library(test_tracks), lib)
 
+    def test_trackdb_get_track(self):
+        lib = trackdb.add_path(test_tracks)
+        lib.scan().join()
+        self.assertEqual(trackdb.get_track(3), lib[3])
+        self.assertIsNone(trackdb.get_track(200))
+
     def test_trackdb_reset(self):
         trackdb.library.TrackAdded.register(1)
         trackdb.library.TrackRemoved.register(1)

trackdb/__init__.py

@@ -20,6 +20,12 @@ def get_library(path):
             return lib
     return None
 
+def get_track(trackid):
+    for lib in library_paths:
+        if (track := lib[trackid]) != None:
+            return track
+    return None
+
 def remove_path(path):
     lib = get_library(path)
     library_paths.remove(lib)

trackdb/library.py

@@ -16,6 +16,9 @@ class LibraryPath:
         self.thread = None
         self.lock   = threading.Lock()
 
+    def __getitem__(self, trackid):
+        return self.tracks.get(trackid)
+
     def __scan_remove(self):
         with self.lock:
             removed = [ (id, track) for (id, track) in self.tracks.items() if not track.exists() ]

trackdb/test_library.py

@@ -49,6 +49,9 @@ class TestLibraryPath(unittest.TestCase):
         self.assertEqual(self.count_removed, 0)
         self.assertEqual(library.NextID, 13)
 
+        self.assertEqual(lib[3], lib.tracks[3])
+        self.assertIsNone(lib[200])
+
         lib.tracks = { id:track for (id, track) in lib.tracks.items() if 2 < id < 11 }
         lib.scan().join()
         self.assertEqual(len(lib.tracks), 13)