From 923d8ddbe984fc36ca331ebecb708800503ca894 Mon Sep 17 00:00:00 2001
From: Drew Weymouth <dweymouth@gmail.com>
Date: Fri, 30 Dec 2022 17:45:57 -0800
Subject: [PATCH] add scrobbling of played tracks

---
 backend/playbackmanager.go | 35 +++++++++++++++++++++++++++++++++++
 backend/util/stopwatch.go  | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)
 create mode 100644 backend/util/stopwatch.go

diff --git a/backend/playbackmanager.go b/backend/playbackmanager.go
index 9358694..d0faffa 100644
--- a/backend/playbackmanager.go
+++ b/backend/playbackmanager.go
@@ -2,12 +2,19 @@ package backend
 
 import (
 	"context"
+	"log"
+	"strconv"
+	"supersonic/backend/util"
 	"supersonic/player"
 	"time"
 
 	subsonic "github.com/dweymouth/go-subsonic"
 )
 
+const (
+	ScrobbleThreshold = 0.6
+)
+
 type PlaybackManager struct {
 	ctx           context.Context
 	cancelPollPos context.CancelFunc
@@ -15,6 +22,9 @@ type PlaybackManager struct {
 	sm            *ServerManager
 	player        *player.Player
 
+	playTimeStopwatch util.Stopwatch
+	curTrackTime      float64
+
 	playQueue        []*subsonic.Child
 	nowPlayingIdx    int64
 	onSongChange     []func(*subsonic.Child)
@@ -27,11 +37,20 @@ func NewPlaybackManager(ctx context.Context, s *ServerManager, p *player.Player)
 		sm:     s,
 		player: p,
 	}
+	// TODO: we get some spurious OnTrackChange callbacks from the player,
+	// especially when loading/playing a new album,
+	// but for now they're pretty much harmless. Investigate later.
 	p.OnTrackChange(func(tracknum int64) {
 		if tracknum >= int64(len(pm.playQueue)) {
 			return
 		}
+		pm.checkScrobble(pm.playTimeStopwatch.Elapsed())
+		pm.playTimeStopwatch.Reset()
+		if pm.player.GetStatus().State == player.Playing {
+			pm.playTimeStopwatch.Start()
+		}
 		pm.nowPlayingIdx = tracknum
+		pm.curTrackTime = float64(pm.playQueue[pm.nowPlayingIdx].Duration)
 		for _, cb := range pm.onSongChange {
 			cb(pm.NowPlaying())
 		}
@@ -41,15 +60,20 @@ func NewPlaybackManager(ctx context.Context, s *ServerManager, p *player.Player)
 		pm.doUpdateTimePos()
 	})
 	p.OnStopped(func() {
+		pm.playTimeStopwatch.Stop()
+		pm.checkScrobble(pm.playTimeStopwatch.Elapsed())
+		pm.playTimeStopwatch.Reset()
 		pm.stopPollTimePos()
 		for _, cb := range pm.onSongChange {
 			cb(nil)
 		}
 	})
 	p.OnPaused(func() {
+		pm.playTimeStopwatch.Stop()
 		pm.stopPollTimePos()
 	})
 	p.OnPlaying(func() {
+		pm.playTimeStopwatch.Start()
 		pm.startPollTimePos()
 	})
 
@@ -107,6 +131,17 @@ func (p *PlaybackManager) PlayAlbum(albumID string) error {
 	return p.player.PlayFromBeginning()
 }
 
+func (p *PlaybackManager) checkScrobble(playDur time.Duration) {
+	if playDur.Seconds() < 0.1 || p.curTrackTime < 0.1 {
+		return
+	}
+	song := p.playQueue[p.nowPlayingIdx]
+	if playDur.Seconds()/p.curTrackTime > ScrobbleThreshold {
+		log.Printf("Scrobbling %q", song.Title)
+		p.sm.Server.Scrobble(song.ID, map[string]string{"time": strconv.FormatInt(time.Now().Unix()*1000, 10)})
+	}
+}
+
 func (p *PlaybackManager) startPollTimePos() {
 	ctx, cancel := context.WithCancel(p.ctx)
 	p.cancelPollPos = cancel
diff --git a/backend/util/stopwatch.go b/backend/util/stopwatch.go
new file mode 100644
index 0000000..f3610a2
--- /dev/null
+++ b/backend/util/stopwatch.go
@@ -0,0 +1,38 @@
+package util
+
+import "time"
+
+type Stopwatch struct {
+	running bool
+	started time.Time
+	elapsed time.Duration
+}
+
+func (s *Stopwatch) Start() {
+	if s.running {
+		return
+	}
+	s.started = time.Now()
+	s.running = true
+}
+
+func (s *Stopwatch) Stop() {
+	if !s.running {
+		return
+	}
+	s.elapsed += time.Since(s.started)
+	s.running = false
+}
+
+func (s *Stopwatch) Elapsed() time.Duration {
+	e := s.elapsed
+	if s.running {
+		e += time.Since(s.started)
+	}
+	return e
+}
+
+func (s *Stopwatch) Reset() {
+	s.running = false
+	s.elapsed = time.Duration(0)
+}