Add pre-alarm action

app.go

@@ -16,11 +16,12 @@ import (
 )
 
 type App struct {
-	cfg       *config.Config
-	db        *reveil.LevelDBStorage
-	router    *gin.Engine
-	srv       *http.Server
-	nextAlarm *time.Timer
+	cfg          *config.Config
+	db           *reveil.LevelDBStorage
+	router       *gin.Engine
+	srv          *http.Server
+	nextAlarm    *time.Timer
+	nextPreAlarm *time.Timer
 }
 
 func NewApp(cfg *config.Config) *App {
@@ -76,11 +77,45 @@ func (app *App) Start() {
 func (app *App) ResetTimer() {
 	if app.nextAlarm != nil {
 		app.nextAlarm.Stop()
+		app.nextPreAlarm = nil
 		app.nextAlarm = nil
 	}
 
+	settings, _ := reveil.ReadSettings(app.cfg.SettingsFile)
+
 	if na, routines, federated, err := reveil.GetNextAlarm(app.cfg, app.db); err == nil && na != nil {
+		if settings != nil && settings.PreAlarmAction != "" {
+			app.nextPreAlarm = time.AfterFunc(time.Until(*na)-settings.PreAlarmActionDelay*time.Minute, func() {
+				app.nextPreAlarm = nil
+
+				settings, err := reveil.ReadSettings(app.cfg.SettingsFile)
+				if err != nil {
+					log.Println("Unable to read settings:", err.Error())
+					return
+				}
+
+				action, err := reveil.LoadAction(app.cfg, settings.PreAlarmAction)
+				if err != nil {
+					log.Println("Unable to load pre-alarm action:", err.Error())
+				}
+
+				cmd, err := action.Launch(settings)
+				if err != nil {
+					log.Println(err.Error())
+					return
+				}
+
+				go func() {
+					err := cmd.Wait()
+					if err != nil {
+						log.Printf("%q: %s", action.Name, err.Error())
+					}
+				}()
+			})
+			log.Println("Next pre-alarm programmed for", time.Time(*na).Add(settings.PreAlarmActionDelay*-1*time.Minute))
+		}
 		app.nextAlarm = time.AfterFunc(time.Until(*na), func() {
+			app.nextPreAlarm = nil
 			app.nextAlarm = nil
 			reveil.RemoveOldAlarmsSingle(app.db)