fix: Ensure each timer can only be scheduled once

If a timer is scheduled with the timer manager while it is already
scheduled, the new exipry time should override the prev. expiry time
instead of adding a second instance of the same timer function.

Signed-off-by: Matthias Blankertz <matthias@blankertz.org>

software/src/app.py

@@ -57,6 +57,7 @@ class PlayerApp:
         self.buttons = deps.buttons(self) if deps.buttons is not None else None
         self.mp3file = None
         self.volume_pos = 3
+        self.paused = False
         self.player.set_volume(VOLUME_CURVE[self.volume_pos])
         self._onIdle()
 
@@ -96,6 +97,10 @@ class PlayerApp:
             self.player.set_volume(VOLUME_CURVE[self.volume_pos])
         elif what == self.buttons.NEXT:
             self._play_next()
+        elif what == self.buttons.PREV:
+            self._play_prev()
+        elif what == self.buttons.PLAY_PAUSE:
+            self._pause_toggle()
 
     def onPlaybackDone(self):
         assert self.mp3file is not None
@@ -136,6 +141,15 @@ class PlayerApp:
             self.playlist = None
             self.playing_tag = None
 
+    def _play_prev(self):
+        if self.playlist is None:
+            return
+        filename = self.playlist.getPrevPath()
+        self._play(filename)
+        if filename is None:
+            self.playlist = None
+            self.playing_tag = None
+
     def _play(self, filename: bytes | None, offset=0):
         if self.mp3file is not None:
             self.player.stop()
@@ -146,8 +160,19 @@ class PlayerApp:
             print(f'Playing {filename!r}')
             self.mp3file = open(filename, 'rb')
             self.player.play(self.mp3file, offset)
+            self.paused = False
             self._onActive()
 
+    def _pause_toggle(self):
+        if self.playlist is None:
+            return
+        if self.paused:
+            self._play(self.playlist.getCurrentPath(), self.pause_offset)
+        else:
+            self.pause_offset = self.player.stop()
+            self.paused = True
+            self._onIdle()
+
     def _onIdle(self):
         self.timer_manager.schedule(time.ticks_ms() + self.idle_timeout_ms, self.onIdleTimeout)
         self.leds.set_state(self.leds.IDLE)

software/src/utils/playlistdb.py

@@ -107,6 +107,17 @@ class BTreeDB(IPlaylistDB):
                 self.setPlaybackOffset(0)
             return self.getCurrentPath()
 
+        def getPrevPath(self):
+            """
+            Select prev track and return path.
+            """
+            if self.pos > 0:
+                self.pos -= 1
+            if self.persist != BTreeDB.PERSIST_NO:
+                self.parent._setPlaylistPos(self.tag, self.pos)
+                self.setPlaybackOffset(0)
+            return self.getCurrentPath()
+
         def setPlaybackOffset(self, offset):
             """
             Store the current position in the track for PERSIST_OFFSET mode

software/src/utils/timer.py

@@ -22,6 +22,7 @@ class TimerManager(object):
 
     def schedule(self, when, what):
         cur_nearest = self.timers[0][0] if len(self.timers) > 0 else None
+        self._remove_timer(what)  # Ensure timer is not already scheduled
         heapq.heappush(self.timers, (when, what))
         if cur_nearest is None or cur_nearest > self.timers[0][0]:
             # New timer is closer than previous closest timer
@@ -31,18 +32,22 @@ class TimerManager(object):
             self.worker_event.set()
 
     def cancel(self, what):
+        remove_idx = self._remove_timer(what)
+        if remove_idx == 0:
+            # Cancel timer was closest timer
+            if self.timer_debug:
+                print("cancel: wake")
+            self.worker_event.set()
+        return True
+
+    def _remove_timer(self, what):
         try:
             (when, _), i = next(filter(lambda item: item[0][1] == what, zip(self.timers, range(len(self.timers)))))
         except StopIteration:
             return False
         del self.timers[i]
         heapq.heapify(self.timers)
-        if i == 0:
-            # Cancel timer was closest timer
-            if self.timer_debug:
-                print("cancel: wake")
-            self.worker_event.set()
-        return True
+        return i
 
     async def _timer_worker(self):
         while True: