Event on next alarm reached

app.go

@@ -15,13 +15,14 @@ import (
 )
 
 type App struct {
-	cfg    *config.Config
-	db     *reveil.LevelDBStorage
-	router *gin.Engine
-	srv    *http.Server
+	cfg       *config.Config
+	db        *reveil.LevelDBStorage
+	router    *gin.Engine
+	srv       *http.Server
+	nextAlarm *time.Timer
 }
 
-func NewApp(cfg *config.Config) App {
+func NewApp(cfg *config.Config) *App {
 	if cfg.DevProxy == "" {
 		gin.SetMode(gin.ReleaseMode)
 	}
@@ -38,21 +39,21 @@ func NewApp(cfg *config.Config) App {
 		log.Fatal("Unable to open the database:", err)
 	}
 
-	// Register routes
-	ui.DeclareRoutes(router, cfg)
-	api.DeclareRoutes(router, cfg, db)
-
-	router.GET("/api/version", func(c *gin.Context) {
-		c.JSON(http.StatusOK, gin.H{"version": Version})
-	})
-
-	// We are ready!
-	app := App{
+	// Prepare struct
+	app := &App{
 		cfg:    cfg,
 		db:     db,
 		router: router,
 	}
 
+	// Register routes
+	ui.DeclareRoutes(router, cfg)
+	api.DeclareRoutes(router, cfg, db, app.ResetTimer)
+
+	router.GET("/api/version", func(c *gin.Context) {
+		c.JSON(http.StatusOK, gin.H{"version": Version})
+	})
+
 	return app
 }
 
@@ -62,13 +63,34 @@ func (app *App) Start() {
 		Handler: app.router,
 	}
 
+	app.ResetTimer()
+
 	log.Printf("Ready, listening on %s\n", app.cfg.Bind)
 	if err := app.srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
 		log.Fatalf("listen: %s\n", err)
 	}
 }
 
+func (app *App) ResetTimer() {
+	if app.nextAlarm != nil {
+		app.nextAlarm.Stop()
+		app.nextAlarm = nil
+	}
+
+	if na, err := reveil.GetNextAlarm(app.db); err == nil && na != nil {
+		app.nextAlarm = time.AfterFunc(time.Until(*na), func() {
+			app.nextAlarm = nil
+			log.Println("RUN WAKEUP FUNC")
+		})
+		log.Println("Next timer programmed for", *na)
+	}
+}
+
 func (app *App) Stop() {
+	if app.nextAlarm != nil {
+		app.nextAlarm.Stop()
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 	if err := app.srv.Shutdown(ctx); err != nil {