Fix PlayerMPD.prev/next() when stopped

* Avoid MPD-related crashes during all prev/next() calls.
* Explicitly handle prev() in stopped state, configurable via
  `playermpd.stopped_prev_action`.
* Explicitly handle next() in stopped state, configurable via
  `playermpd.stopped_next_action`.
* Explicitly handle next() when reaching the end of the playlist:
  jukebox-daemon will now stop playing by default (similar to v2).
  It can also be configured to restart the playlist instead by setting
  the new config option `playermpd.end_of_playlist_next_action: rewind`
  or to ignore the action completely.

Fixes #2294
Fixes #2327

Co-authored-by: pabera <[email protected]>

resources/default-settings/jukebox.default.yaml

@@ -87,6 +87,12 @@ playermpd:
     update_on_startup: true
     check_user_rights: true
   mpd_conf: ~/.config/mpd/mpd.conf
+  # Must be one of: 'none', 'stop', 'rewind':
+  end_of_playlist_next_action: stop
+  # Must be one of: 'none', 'prev', 'rewind':
+  stopped_prev_action: prev
+  # Must be one of: 'none', 'next', 'rewind':
+  stopped_next_action: next
 rpc:
   tcp_port: 5555
   websocket_port: 5556

src/jukebox/components/playermpd/__init__.py

@@ -156,6 +156,20 @@ def __init__(self):
         self.second_swipe_action = None
         self.decode_2nd_swipe_option()
 
+        self.end_of_playlist_next_action_dict = {'rewind': self.rewind,
+                                                 'stop': self.stop,
+                                                 'none': lambda: None}
+        self.end_of_playlist_next_action = None
+        self.stopped_prev_action_dict = {'rewind': self.rewind,
+                                         'prev': self._prev_in_stopped_state,
+                                         'none': lambda: None}
+        self.stopped_prev_action = None
+        self.stopped_next_action_dict = {'rewind': self.rewind,
+                                         'next': self._next_in_stopped_state,
+                                         'none': lambda: None}
+        self.stopped_next_action = None
+        self.decode_prev_next_actions()
+
         self.mpd_client = mpd.MPDClient()
         self.coverart_cache_manager = CoverartCacheManager()
 
@@ -231,6 +245,31 @@ def decode_2nd_swipe_option(self):
                                                          custom_action['args'],
                                                          custom_action['kwargs'])
 
+    def decode_prev_next_actions(self):
+        end_of_playlist_next_action = cfg.setndefault('playermpd', 'end_of_playlist_next_action', value='').lower()
+        if end_of_playlist_next_action not in self.end_of_playlist_next_action_dict:
+            end_of_playlist_next_action = 'stop'
+            logger.error(f"Config playermpd.end_of_playlist_next_action must be one of "
+                         f"{self.end_of_playlist_next_action.keys()}. "
+                         f"Using default 'stop'")
+        self.end_of_playlist_next_action = self.end_of_playlist_next_action_dict[end_of_playlist_next_action]
+
+        stopped_prev_action = cfg.setndefault('playermpd', 'stopped_prev_action', value='').lower()
+        if stopped_prev_action not in self.stopped_prev_action_dict:
+            stopped_prev_action = 'prev'
+            logger.error(f"Config playermpd.stopped_prev_action must be one of "
+                         f"{self.stopped_prev_action.keys()}. "
+                         f"Using default 'prev'")
+        self.stopped_prev_action = self.stopped_prev_action_dict[stopped_prev_action]
+
+        stopped_next_action = cfg.setndefault('playermpd', 'stopped_prev_action', value='').lower()
+        if stopped_next_action not in self.stopped_prev_action_dict:
+            stopped_next_action = 'prev'
+            logger.error(f"Config playermpd.stopped_next_action must be one of "
+                         f"{self.stopped_next_action.keys()}. "
+                         f"Using default 'next'")
+        self.stopped_next_action = self.stopped_prev_action_dict[stopped_prev_action]
+
     def mpd_retry_with_mutex(self, mpd_cmd, *args):
         """
         This method adds thread saftey for acceses to mpd via a mutex lock,
@@ -327,15 +366,48 @@ def pause(self, state: int = 1):
     @plugs.tag
     def prev(self):
         logger.debug("Prev")
+        if self.mpd_status['state'] == 'stop':
+            logger.debug('Player is stopped, calling stopped_prev_action')
+            return self.stopped_prev_action()
+        try:
+            with self.mpd_lock:
+                self.mpd_client.previous()
+        except mpd.base.CommandError:
+            # This shouldn't happen in reality, but we still catch
+            # this error to avoid crashing the player thread:
+            logger.warning('Failed to go to previous song, ignoring')
+
+    def _prev_in_stopped_state(self):
         with self.mpd_lock:
-            self.mpd_client.previous()
+            self.mpd_client.play(max(0, int(self.mpd_status['pos']) - 1))
 
     @plugs.tag
     def next(self):
         """Play next track in current playlist"""
         logger.debug("Next")
+        if self.mpd_status['state'] == 'stop':
+            logger.debug('Player is stopped, calling stopped_next_action')
+            return self.stopped_next_action()
+        playlist_len = int(self.mpd_status.get('playlistlength', -1))
+        current_pos = int(self.mpd_status.get('pos', 0))
+        if current_pos == playlist_len - 1:
+            logger.debug(f'next() called during last song ({current_pos}) of '
+                         f'playlist (len={playlist_len}), running end_of_playlist_next_action.')
+            return self.end_of_playlist_next_action()
+        try:
+            with self.mpd_lock:
+                self.mpd_client.next()
+        except mpd.base.CommandError:
+            # This shouldn't happen in reality, but we still catch
+            # this error to avoid crashing the player thread:
+            logger.warning('Failed to go to next song, ignoring')
+
+    def _next_in_stopped_state(self):
+        pos = int(self.mpd_status['pos']) + 1
+        if pos > int(self.mpd_status['playlistlength']) - 1:
+            return self.end_of_playlist_next_action()
         with self.mpd_lock:
-            self.mpd_client.next()
+            self.mpd_client.play(pos)
 
     @plugs.tag
     def seek(self, new_time):