type QueueStore[_ any] struct {
	sync.RWMutex
	entryLimit uint64
	directory  string
	fileExt    string

	entries map[string]int64 // key -> modtime as unix nano
}

// NewQueueStore - Creates an instance for QueueStore.
func NewQueueStore[I any](directory string, limit uint64, ext string) *QueueStore[I] {
	if limit == 0 {
		limit = defaultLimit
	}

	if ext == "" {
		ext = defaultExt
	}

	return &QueueStore[I]{

	var queueStore store.Store[event.Event]
	if args.QueueDir != "" {
		queueDir := filepath.Join(args.QueueDir, storePrefix+"-nsq-"+id)
		queueStore = store.NewQueueStore[event.Event](queueDir, args.QueueLimit, event.StoreExtension)
		if err := queueStore.Open(); err != nil {
			return nil, fmt.Errorf("unable to initialize the queue store of NSQ `%s`: %w", id, err)
		}
	}

	ctx, cancel := context.WithCancel(ctx)

	var queueStore store.Store[event.Event]
	if args.QueueDir != "" {
		queueDir := filepath.Join(args.QueueDir, storePrefix+"-webhook-"+id)
		queueStore = store.NewQueueStore[event.Event](queueDir, args.QueueLimit, event.StoreExtension)
		if err := queueStore.Open(); err != nil {
			cancel()
			return nil, fmt.Errorf("unable to initialize the queue store of Webhook `%s`: %w", id, err)
		}

		args.KeepAlive = 10 * time.Second
	}

	var queueStore store.Store[event.Event]
	if args.QueueDir != "" {
		queueDir := filepath.Join(args.QueueDir, storePrefix+"-mqtt-"+id)
		queueStore = store.NewQueueStore[event.Event](queueDir, args.QueueLimit, event.StoreExtension)
		if err := queueStore.Open(); err != nil {
			return nil, fmt.Errorf("unable to initialize the queue store of MQTT `%s`: %w", id, err)
		}
	}

	var queueStore store.Store[event.Event]
	if args.QueueDir != "" {
		queueDir := filepath.Join(args.QueueDir, storePrefix+"-redis-"+id)
		queueStore = store.NewQueueStore[event.Event](queueDir, args.QueueLimit, event.StoreExtension)
		if err := queueStore.Open(); err != nil {
			return nil, fmt.Errorf("unable to initialize the queue store of Redis `%s`: %w", id, err)
		}
	}