add support for OpenSubsonic playbackReport extension (#910)

* add support for OpenSubsonic playbackReport extension

* better style

backend/mediaprovider/mediaprovider.go

@@ -302,6 +302,10 @@ type CanSavePlayQueue interface {
 	GetPlayQueue() (*SavedPlayQueue, error)
 }
 
+type CanReportPlayback interface {
+	ReportPlayback(trackID string, positionMs int64, state string) error
+}
+
 type LyricsProvider interface {
 	GetLyrics(track *Track) (*Lyrics, error)
 }

backend/mediaprovider/subsonic/subsonicmediaprovider.go

@@ -37,6 +37,9 @@ type subsonicMediaProvider struct {
 
 	radiosCached   []*mediaprovider.RadioStation
 	radiosCachedAt int64 // unix
+
+	playbackReportOnce      sync.Once
+	playbackReportSupported bool
 }
 
 func SubsonicMediaProvider(subsonicClient *subsonic.Client) mediaprovider.MediaProvider {
@@ -459,6 +462,30 @@ func (s *subsonicMediaProvider) GetLyrics(track *mediaprovider.Track) (*mediapro
 // CanSavePlayQueue interface
 var _ mediaprovider.CanSavePlayQueue = (*subsonicMediaProvider)(nil)
 
+// CanReportPlayback interface
+var _ mediaprovider.CanReportPlayback = (*subsonicMediaProvider)(nil)
+
+func (s *subsonicMediaProvider) ReportPlayback(trackID string, positionMs int64, state string) error {
+	s.playbackReportOnce.Do(func() {
+		ext, err := s.client.GetOpenSubsonicExtensions()
+		s.playbackReportSupported = err == nil && slices.ContainsFunc(ext,
+			func(e *subsonic.OpenSubsonicExtension) bool {
+				return e.Name == subsonic.PlaybackReport
+			})
+	})
+	if !s.playbackReportSupported {
+		return nil
+	}
+	ignoreScrobble := true
+	return s.client.ReportPlayback(subsonic.ReportPlaybackParameters{
+		MediaID:        trackID,
+		MediaType:      subsonic.PlaybackMediaTypeSong,
+		PositionMs:     positionMs,
+		State:          subsonic.PlaybackState(state),
+		IgnoreScrobble: &ignoreScrobble,
+	})
+}
+
 func (s *subsonicMediaProvider) SavePlayQueue(trackIDs []string, currentTrackIdx int, timeSeconds int) error {
 	if len(trackIDs) == 0 {
 		return nil // don't save an empty queue

backend/playbackengine.go

@@ -170,17 +170,24 @@ func (p *playbackEngine) registerPlayerCallbacks(pl player.BasePlayer) {
 	pl.OnSeek(func() {
 		p.handleTimePosUpdate(true)
 		p.invokeNoArgCallbacks(p.onSeek)
+		seekState := "playing"
+		if p.PlaybackStatus().State == player.Paused {
+			seekState = "paused"
+		}
+		p.reportPlayback(seekState)
 	})
 	pl.OnStopped(p.handleOnStopped)
 	pl.OnPaused(func() {
 		p.playTimeStopwatch.Stop()
 		p.stopPollTimePos()
 		p.invokeNoArgCallbacks(p.onPaused)
+		p.reportPlayback("paused")
 	})
 	pl.OnPlaying(func() {
 		p.playTimeStopwatch.Start()
 		p.startPollTimePos()
 		p.invokeNoArgCallbacks(p.onPlaying)
+		p.reportPlayback("playing")
 	})
 }
 
@@ -926,6 +933,7 @@ func (p *playbackEngine) handleOnStopped() {
 	p.handleTimePosUpdate(false)
 	p.invokeOnSongChangeCallbacks()
 	p.invokeNoArgCallbacks(p.onStopped)
+	p.reportPlayback("stopped")
 	p.alreadyScrobbled = false
 	p.wasStopped = true
 	p.nowPlayingIdx = -1
@@ -1091,6 +1099,7 @@ func (p *playbackEngine) sendNowPlayingScrobble() {
 		track.PlayCount += 1
 	}
 	go p.sm.Server.TrackBeganPlayback(track.ID)
+	p.reportPlayback("starting")
 }
 
 // creates a deep copy of the track info so that we can maintain our own state
@@ -1113,6 +1122,22 @@ func (p *playbackEngine) invokeOnSongChangeCallbacks() {
 	p.lastScrobbled = nil
 }
 
+func (p *playbackEngine) reportPlayback(state string) {
+	reporter, ok := p.sm.Server.(mediaprovider.CanReportPlayback)
+	if !ok {
+		return
+	}
+	if p.getPlayQueueLength() == 0 || p.nowPlayingIdx < 0 {
+		return
+	}
+	np := p.NowPlaying()
+	if np == nil || np.Metadata().Type != mediaprovider.MediaItemTypeTrack {
+		return
+	}
+	posMs := int64(p.latestTrackPosition * 1000)
+	go reporter.ReportPlayback(np.Metadata().ID, posMs, state)
+}
+
 func (pm *playbackEngine) invokeNoArgCallbacks(cbs []func()) {
 	if pm.callbacksDisabled {
 		return