Fix song counter and inconsistent queue state

zyrarbot/music/music_player.py

@@ -189,12 +189,30 @@ 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
 
-        next_index = self._next_index(state, advance=advance)
+        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
             state.current = None
@@ -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)