Fix song counter and inconsistent queue state

tests/test_music_player.py

@@ -25,15 +25,36 @@ class MusicPlayerQueueTest(unittest.IsolatedAsyncioTestCase):
         self.assertIs(voice_client.playing, track)
         self.assertEqual(player.state(GUILD).index, 0)
 
-    async def test_single_play_budget_drops_track_from_queue(self):
+    async def test_last_play_remains_pointed_to_until_playback_finishes(self):
         player, _ = build_player(default_plays=1)
         track = FakeTrack("a")
         await player.enqueue(GUILD, track)
 
         state = player.state(GUILD)
+        self.assertEqual(state.queue, [track])
+        self.assertEqual(state.index, 0)
+        self.assertIs(state.current, track)
+
+        await player.play_next(GUILD, advance=True)
+
         self.assertEqual(state.queue, [])
         self.assertEqual(state.index, -1)
-        self.assertIs(state.current, track)
+        self.assertIsNone(state.current)
+
+    async def test_last_play_of_recreated_track_is_removed_after_callback(self):
+        player, _, state = await self._queue_abc(default_plays=2)
+        state.loop_mode = LoopMode.TRACK
+
+        await player.play_next(GUILD, advance=True)
+        self.assertEqual([track.id for track in state.queue], ["a", "b", "c"])
+        self.assertEqual(state.index, 0)
+        self.assertEqual(state.current.plays_left, 0)
+
+        await player.play_next(GUILD, advance=True)
+
+        self.assertEqual([track.id for track in state.queue], ["b", "c"])
+        self.assertEqual(state.index, 0)
+        self.assertEqual(state.current.id, "b")
 
     async def test_enqueue_while_playing_only_appends(self):
         _, _, state = await self._queue_abc()

zyrarbot/music/music_player.py

@@ -189,11 +189,29 @@ class MusicPlayer:
         if state.consume_jump():
             advance = False
 
+        # Utwór z ostatnim odtworzeniem musi pozostać w kolejce do chwili
+        # zakończenia źródła. W przeciwnym razie panel dostaje `current`, ale
+        # `queue_index` wskazuje pozycję spoza kolejki podczas faktycznego
+        # odtwarzania ostatniej kopii.
+        retired_index: int | None = None
+        if advance and state.current is not None and 0 <= state.index < len(state.queue):
+            current = state.queue[state.index]
+            if current is state.current and self.plays_left(current) <= 0:
+                retired_index = state.index
+                state.queue.pop(state.index)
+                state.index -= 1
+
         if not state.queue:
             state.index = -1
             state.current = None
+            await self.trigger_state_change()
             return
 
+        if retired_index is not None:
+            next_index = retired_index
+            if state.loop_mode.loops_queue:
+                next_index %= len(state.queue)
+        else:
             next_index = self._next_index(state, advance=advance)
         if next_index >= len(state.queue):
             state.index = next_index
@@ -220,13 +238,12 @@ class MusicPlayer:
         track.plays_left = self.plays_left(track) - 1
         track.volume = state.volume
 
+        state.queue[next_index] = track
         if track.plays_left <= 0:
-            state.queue.pop(next_index)
-            state.index = next_index - 1
+            # Usunięcie nastąpi dopiero po callbacku discord.py, po tym jak
+            # ostatnie odtworzenie rzeczywiście się zakończy.
             if state.loop_mode.loops_track:
                 state.loop_mode = LoopMode.OFF
-        else:
-            state.queue[next_index] = track
 
         state.current = track
         self._record_history(guild_id, track)