package main

var (
  ctx context.Context
  cancel func()
)

func main() {
  ctx, cancel := context.WithCancel(context.Background)
  defer cancel() // ensures on exit the routines are shut

  // waits for ^c in the background
  go interruptWatcher()

  // waits for file changes in /tmp or for context cancel
  watch(ctx)
}

func watch(ctx context.Context) {
  events := make(chan notify.EventInfo, 1)

  notify.Watch("/tmp", events, notify.InDelete, notify.InCloseWrite, notify.InMovedTo)

  for {
      select {
      case event := <-events:
        fmt.Printf("Handling event %#v\n", event)
      case <-ctx.Done(): // ^c notifies on this and we know to exit
        notify.Stop(events)
        return
    }
  }
}

func interruptWatcher() {
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)

	for {
		select {
		case sig := <-sigs:
			switch sig {
			case syscall.SIGINT, syscall.SIGTERM:
				fmt.Printf("Shutting down on %s", sig)
				cancel()
			}
		case <-ctx.Done():
			return
		}
	}
}