feat(podcasts): add an option to purge old episodes

* Record podcast episode plays in ModifiedAt field.

* Added podcast purger.

server/ctrlsubsonic/handlers_raw.go

@@ -106,6 +106,24 @@ func streamUpdateStats(dbc *db.DB, userID, albumID int, playTime time.Time) erro
 	return nil
 }
 
+func streamUpdatePodcastEpisodeStats(dbc *db.DB, peID int) error {
+	var pe db.PodcastEpisode
+	err := dbc.
+		Where("id=?", peID).
+		First(&pe).
+		Error
+	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
+		return fmt.Errorf("find podcast episode: %w", err)
+	}
+
+	pe.ModifiedAt = time.Now()
+
+	if err := dbc.Save(&pe).Error; err != nil {
+		return fmt.Errorf("save podcast episode: %w", err)
+	}
+	return nil
+}
+
 const (
 	coverDefaultSize = 600
 	coverCacheFormat = "png"
@@ -271,7 +289,15 @@ func (c *Controller) ServeStream(w http.ResponseWriter, r *http.Request) *spec.R
 	if track, ok := file.(*db.Track); ok && track.Album != nil {
 		defer func() {
 			if err := streamUpdateStats(c.DB, user.ID, track.Album.ID, time.Now()); err != nil {
-				log.Printf("error updating status: %v", err)
+				log.Printf("error updating track status: %v", err)
+			}
+		}()
+	}
+
+	if pe, ok := file.(*db.PodcastEpisode); ok {
+		defer func() {
+			if err := streamUpdatePodcastEpisodeStats(c.DB, pe.ID); err != nil {
+				log.Printf("error updating podcast episode status: %v", err)
 			}
 		}()
 	}

server/server.go

@@ -389,6 +389,31 @@ func (s *Server) StartPodcastRefresher(dur time.Duration) (FuncExecute, FuncInte
 		}
 }
 
+func (s *Server) StartPodcastPurger(maxAge time.Duration) (FuncExecute, FuncInterrupt) {
+	ticker := time.NewTicker(24 * time.Hour)
+	done := make(chan struct{})
+	waitFor := func() error {
+		for {
+			select {
+			case <-done:
+				return nil
+			case <-ticker.C:
+				if err := s.podcast.PurgeOldPodcasts(maxAge); err != nil {
+					log.Printf("error purging old podcasts: %v", err)
+				}
+			}
+		}
+	}
+	return func() error {
+			log.Printf("starting job 'podcast purger'\n")
+			return waitFor()
+		}, func(_ error) {
+			// stop job
+			ticker.Stop()
+			done <- struct{}{}
+		}
+}
+
 func (s *Server) StartSessionClean(dur time.Duration) (FuncExecute, FuncInterrupt) {
 	ticker := time.NewTicker(dur)
 	done := make(chan struct{})