private async Task ExecuteAddCardCommand()
        {
            if (string.IsNullOrEmpty(CardName.DefaultString()))
            {
                await DisplayAlert("Information", "Enter the name!", "OK");

                return;
            }

            if (string.IsNullOrEmpty(CardNumber.DefaultString()))
            {
                await DisplayAlert("Information", "Enter the card number!", "OK");

                return;
            }

            if (CardNumber.DefaultString().Length < 16 ||
                CardNumber.DefaultString().Length < 15)
            {
                await DisplayAlert("Information", "Incomplete card number!", "OK");

                return;
            }

            if (!CreditCardHelper.IsValidCreditCardNumber(CardNumber))
            {
                await DisplayAlert("Information", "Card number is invalid!", "OK");

                return;
            }

            if (string.IsNullOrEmpty(CardExpirationDate.DefaultString()))
            {
                await DisplayAlert("Information", "Enter the expiration date!", "OK");

                return;
            }

            if (string.IsNullOrEmpty(CardCVV.DefaultString()))
            {
                await DisplayAlert("Information", "Enter the secuity code!", "OK");

                return;
            }

            var confirm = await DisplayAlert("Confirmation", "Confirm registration?", "YES", "NO");

            if (confirm)
            {
                var card = new Card()
                {
                    cardName           = CardName,
                    cardNumber         = CardNumber.RemoveNonNumbers(),
                    cardExpirationDate = CardExpirationDate,
                    cardCVV            = CardCVV,
                    cardFlag           = CardFlag
                };

                card.cardFlag = CreditCardHelper.FindFlagCard(card.cardNumber);
                MessagingCenter.Send(this, "addCard", card);
                await PopupNavigation.Instance.PopAsync(true);
            }
        }