explicit info in GUI for playlist

internal/playback/playlist_controller.go

@@ -17,6 +17,7 @@ const (
 type PlaylistEvent struct {
 	Revision uint64
 	Kind     PlaylistEventKind
+	Failure  Status
 }
 
 // PlaylistReadiness is retained as an alias for callers that only publish
@@ -47,13 +48,24 @@ type PlaylistController struct {
 	mu          sync.RWMutex
 	snapshot    PlaylistSnapshot
 	hasSnapshot bool
+	failure     PlaylistFailure
+}
+
+type PlaylistFailure struct {
+	EntryIndex int
+	EntryName  string
+	Revision   uint64
+	Policy     PlaylistFailurePolicy
+	Status     Status
 }
 
 type PlaylistSnapshot struct {
-	State    PlaylistState
-	Entry    PlaylistEntry
-	Revision uint64
-	Timing   PlaylistTimingState
+	State      PlaylistState
+	Entry      PlaylistEntry
+	Revision   uint64
+	Timing     PlaylistTimingState
+	Failure    PlaylistFailure
+	HasFailure bool
 }
 
 var (
@@ -155,6 +167,7 @@ func (c *PlaylistController) Run(
 				continue
 			}
 			if apply {
+				c.clearFailure()
 				stopTimer()
 				select {
 				case <-ctx.Done():
@@ -179,6 +192,13 @@ func (c *PlaylistController) Run(
 					continue
 				}
 				stopTimer()
+				c.setFailure(PlaylistFailure{
+					EntryIndex: state.CurrentIndex,
+					EntryName:  c.playlist.Entries[state.CurrentIndex].Name,
+					Revision:   revision,
+					Policy:     c.playlist.OnFailure,
+					Status:     ready.Failure,
+				})
 				// A failed entry must not retain a live or apparently active
 				// duration clock, even when the policy is to wait.
 				timing = NewPlaylistTiming(revision, timing.Duration)
@@ -285,15 +305,29 @@ func (c *PlaylistController) publish(
 
 	c.mu.Lock()
 	c.snapshot = PlaylistSnapshot{
-		State:    state,
-		Entry:    entry,
-		Revision: revision,
-		Timing:   timing,
+		State:      state,
+		Entry:      entry,
+		Revision:   revision,
+		Timing:     timing,
+		Failure:    c.failure,
+		HasFailure: c.failure.Revision != 0,
 	}
 	c.hasSnapshot = true
 	c.mu.Unlock()
 }
 
+func (c *PlaylistController) setFailure(failure PlaylistFailure) {
+	c.mu.Lock()
+	c.failure = failure
+	c.mu.Unlock()
+}
+
+func (c *PlaylistController) clearFailure() {
+	c.mu.Lock()
+	c.failure = PlaylistFailure{}
+	c.mu.Unlock()
+}
+
 func stopPlaylistTimer(timer playlistTimer) {
 	if timer == nil || timer.Stop() {
 		return