Enhance play method for playlist support (#172)

Refactor play method to support playlists and sequential playback.

linux_voice_assistant/mpv_player.py

@@ -18,6 +18,7 @@ class MpvMediaPlayer:
         self._log = logging.getLogger(self.__class__.__name__)
         self._player = LibMpvPlayer(device=device)
         self._done_callback: Optional[Callable[[], None]] = None
+        self._playlist: List[str] = []
 
         self._log.debug("MpvMediaPlayer initialized (device=%s)", device)
 
@@ -31,34 +32,55 @@ class MpvMediaPlayer:
         Play a media URL.
 
         Args:
-            url: Media URL or list of URLs (LVA currently uses a single URL).
+            url: Media URL or list of URLs for sequential playback.
             done_callback: Optional callback invoked when playback finishes.
             stop_first: Kept for API compatibility.
         """
-        # LVA currently only uses single URLs
-        if isinstance(url, list):
-            self._log.debug("Received URL list, using first entry")
-            url = url[0]
+        # Handle single URL vs list
+        if isinstance(url, str):
+            urls = [url]
+        else:
+            urls = list(url)  # Copy the list
         
-        # Track is changing - only stop for replacement if actually playing
+        if not urls:
+            self._log.warning("play() called with empty URL list")
+            return
+
+        # Track is changing - stop if needed
         if self._done_callback is not None:
             if self._player.state() != PlayerState.IDLE:
-                self._log.debug(
-                    "Stopping active playback before starting new media"
-                )
+                self._log.debug("Stopping active playback before starting new media")
                 self._player.stop(for_replacement=True)
             self._done_callback = None
 
-        self._log.info("Playing media: %s", url)
-        self._log.debug(
-            "play(url=%s, stop_first=%s, done_callback=%s)",
-            url,
-            stop_first,
-            bool(done_callback),
-        )
+        self._log.info("Playing %d URL(s): %s", len(urls), urls[0])
         
+        # Store playlist and callback
+        self._playlist = urls
         self._done_callback = done_callback
-        self._player.play(url, done_callback=done_callback, stop_first=stop_first)
+        
+        # Start playing first URL
+        next_url = self._playlist.pop(0)
+        self._player.play(next_url, done_callback=self._on_track_finished, stop_first=stop_first)
+
+    def _on_track_finished(self) -> None:
+        """Called when a track finishes - plays next or invokes done callback."""
+        if self._playlist:
+            # More tracks to play
+            next_url = self._playlist.pop(0)
+            self._log.debug("Playing next URL from playlist: %s", next_url)
+            self._player.play(next_url, done_callback=self._on_track_finished, stop_first=False)
+        else:
+            # Playlist finished
+            callback = self._done_callback
+            self._done_callback = None
+            
+            if callback:
+                self._log.debug("Playlist finished, invoking done_callback")
+                try:
+                    callback()
+                except Exception as e:
+                    self._log.exception("Error in done_callback: %s", e)
 
     def pause(self) -> None:
         """Pause playback."""