[MM-36198] - Activating a user in System Console does not respect cloud user limits (#17719)

* [MM-36198] - Activating a user in System Console does not respect cloud user limits

* feedback impl

* improve error check

app/cloud.go

@@ -79,6 +79,52 @@ func (a *App) SendAdminUpgradeRequestEmail(username string, subscription *model.
 	return nil
 }
 
+func (a *App) GetSubscriptionStats() (*model.SubscriptionStats, *model.AppError) {
+	if a.Srv().License() == nil || !*a.Srv().License().Features.Cloud {
+		return nil, model.NewAppError("app.GetSubscriptionStats", "api.cloud.license_error", nil, "", http.StatusInternalServerError)
+	}
+
+	subscription, appErr := a.Cloud().GetSubscription("")
+	if appErr != nil {
+		return nil, model.NewAppError("app.GetSubscriptionStats", "api.cloud.request_error", nil, appErr.Error(), http.StatusInternalServerError)
+	}
+
+	count, err := a.Srv().Store.User().Count(model.UserCountOptions{})
+	if err != nil {
+		return nil, model.NewAppError("app.GetSubscriptionStats", "app.user.get_total_users_count.app_error", nil, err.Error(), http.StatusInternalServerError)
+	}
+	cloudUserLimit := *a.Config().ExperimentalSettings.CloudUserLimit
+
+	s := cloudUserLimit - count
+
+	return &model.SubscriptionStats{
+		RemainingSeats: int(s),
+		IsPaidTier:     subscription.IsPaidTier,
+	}, nil
+}
+
+func (a *App) CheckCloudAccountAtLimit() (bool, *model.AppError) {
+	if a.Srv().License() == nil || (a.Srv().License() != nil && !*a.Srv().License().Features.Cloud) {
+		// Not cloud instance, so no at limit checks
+		return false, nil
+	}
+
+	stats, err := a.GetSubscriptionStats()
+	if err != nil {
+		return false, err
+	}
+
+	if stats.IsPaidTier == "true" {
+		return false, nil
+	}
+
+	if stats.RemainingSeats < 1 {
+		return true, nil
+	}
+
+	return false, nil
+}
+
 func (a *App) CheckAndSendUserLimitWarningEmails(c *request.Context) *model.AppError {
 	if a.Srv().License() == nil || (a.Srv().License() != nil && !*a.Srv().License().Features.Cloud) {
 		// Not cloud instance, do nothing