protected void CouponButton_Click(object sender, EventArgs e)
 {
     if (string.IsNullOrEmpty(CouponTextBox.Text))
     {
         MessageUserControl.ShowInfo("Please enter a valid coupon.");
     }
     else
     {
         CouponController sysmgr = new CouponController();
         Coupon           coupon = sysmgr.ValidateCoupon(CouponTextBox.Text);
         if (coupon == null)
         {
             MessageUserControl.ShowInfo("Please enter a valid coupon.");
         }
         else
         {
             MessageUserControl.TryRun(() =>
             {
                 decimal couponDiscount = decimal.Parse(coupon.CouponDiscount.ToString());
                 decimal discount       = couponDiscount / 100;
                 CouponIDLabel.Text     = coupon.CouponID.ToString();
                 Label3.Visible         = true;
                 decimal discountValue  = decimal.Parse(SubTotalLabel.Text) * discount;
                 DiscountLabel.Text     = discountValue.ToString();
                 decimal total          = decimal.Parse(TotalLabel.Text);
                 total          -= discountValue;
                 TotalLabel.Text = total.ToString();
             }, "Coupon", "Coupon successfully applied.");
             MainView.ActiveViewIndex = 2;
         }
     }
 }