fix(reminder): decrement limit properly

reminder/handler.go

@@ -132,6 +132,11 @@
 	go func(c tb.Context, reminder Reminder) {
 		time.Sleep(time.Until(reminder.Time))
 
+		ctx := sentry.SetHubOnContext(context.Background(), sentry.CurrentHub())
+		span := sentry.StartSpan(ctx, "reminder.trigger", sentry.WithTransactionName("Reminder Trigger"), sentry.WithTransactionSource(sentry.SourceTask))
+		defer span.Finish()
+		ctx = span.Context()
+
 		template := fmt.Sprintf(
 			"Hi %s! I'm reminding you to %s. Have a great day!",
 			strings.Join(reminder.Subject, ", "),
@@ -141,9 +146,14 @@
 		if err != nil {
 			sentry.GetHubFromContext(ctx).CaptureException(err)
 		}
+
+		err = d.DecrementUserLimit(ctx, c.Sender().ID)
+		if err != nil {
+			sentry.GetHubFromContext(ctx).CaptureException(err)
+		}
 	}(c, reminder)
 
-	err = d.IncrementUserLimit(ctx, c.Sender().ID, reminderCount+1)
+	err = d.IncrementUserLimit(ctx, c.Sender().ID)
 	if err != nil {
 		sentry.GetHubFromContext(ctx).CaptureException(err)
 	}

reminder/user_limiter.go

@@ -26,11 +26,52 @@
 	return strconv.Atoi(string(value))
 }
 
-func (d *Dependency) IncrementUserLimit(ctx context.Context, id int64, value int) error {
+func (d *Dependency) IncrementUserLimit(ctx context.Context, id int64) error {
 	span := sentry.StartSpan(ctx, "reminder.increment_user_limit")
 	defer span.Finish()
 
-	err := d.memory.Set(fmt.Sprintf("reminder:user_limit:%d", id), []byte(strconv.Itoa(value)))
+	value, err := d.memory.Get(fmt.Sprintf("reminder:user_limit:%d", id))
+	if err != nil && !errors.Is(err, bigcache.ErrEntryNotFound) {
+		return fmt.Errorf("acquiring value from memory: %w", err)
+	}
+
+	if value == nil || string(value) == "" {
+		value = []byte("0")
+	}
+
+	i, err := strconv.Atoi(string(value))
+	if err != nil {
+		return fmt.Errorf("invalid value: %s", value)
+	}
+
+	err = d.memory.Set(fmt.Sprintf("reminder:user_limit:%d", id), []byte(strconv.Itoa(i+1)))
+	if err != nil {
+		return fmt.Errorf("setting value to memory: %w", err)
+	}
+
+	return nil
+}
+
+func (d *Dependency) DecrementUserLimit(ctx context.Context, id int64) error {
+	span := sentry.StartSpan(ctx, "reminder.decrement_user_limit")
+	defer span.Finish()
+
+	value, err := d.memory.Get(fmt.Sprintf("reminder:user_limit:%d", id))
+	if err != nil && !errors.Is(err, bigcache.ErrEntryNotFound) {
+		return fmt.Errorf("acquiring value from memory: %w", err)
+	}
+
+	if value == nil || string(value) == "" {
+		// Don't decrement anything that's empty
+		return nil
+	}
+
+	i, err := strconv.Atoi(string(value))
+	if err != nil {
+		return fmt.Errorf("invalid value: %s", value)
+	}
+
+	err = d.memory.Set(fmt.Sprintf("reminder:user_limit:%d", id), []byte(strconv.Itoa(i-1)))
 	if err != nil {
 		return fmt.Errorf("setting value to memory: %w", err)
 	}

reminder/user_limiter_test.go

@@ -35,7 +35,7 @@ func TestUserLimit(t *testing.T) {
 		t.Errorf("expecting userLimit to be 0, instead got %d", userLimit)
 	}
 
-	err = dependency.IncrementUserLimit(ctx, 123, 1)
+	err = dependency.IncrementUserLimit(ctx, 123)
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -48,4 +48,18 @@ func TestUserLimit(t *testing.T) {
 	if userLimit2 != 1 {
 		t.Errorf("expecting userLimit2 to be 1, instead got %d", userLimit2)
 	}
+
+	err = dependency.DecrementUserLimit(ctx, 123)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	userLimit3, err := dependency.CheckUserLimit(ctx, 123)
+	if err != nil {
+		t.Errorf("unexpected error: %s", err.Error())
+	}
+
+	if userLimit3 != 0 {
+		t.Errorf("expecting userLimit3 to be 0, instead got %d", userLimit2)
+	}
 }