protected void btnRemove_Click(object sender, EventArgs e)
        {
            if (!string.IsNullOrWhiteSpace(lblOfferAmount.Text))
            {
                string message = string.Empty;
                calculateOrderAmount = new CalculateOrderAmount(Convert.ToDouble(lblOfferAmount.Text), 0.00);
                discountCommand      = new DiscountCommand(calculateOrderAmount);
                cashBackCommand      = new CashBackCommand(calculateOrderAmount);

                if (rblOffers.SelectedIndex == 0)
                {
                    command = cashBackCommand;
                    message = "Cash back offer is not applied";
                    System.Text.StringBuilder sb = new System.Text.StringBuilder();
                    sb.Append("<script type = 'text/javascript'>");
                    sb.Append("window.onload=function(){");
                    sb.Append("alert('");
                    sb.Append(message);
                    sb.Append("')};");
                    sb.Append("</script>");
                    ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", sb.ToString());
                }
                else if (rblOffers.SelectedIndex == 1)
                {
                    command = discountCommand;
                    lblOfferAmount.Visible = false;
                    lblTotalAmount.Text    = command.UnExecute().ToString();
                }

                btnApply.Enabled  = true;
                btnRemove.Enabled = false;
            }
        }
        protected void btnApply_Click(object sender, EventArgs e)
        {
            if (!string.IsNullOrWhiteSpace(lblTotalAmount.Text))
            {
                string message = string.Empty;
                calculateOrderAmount = new CalculateOrderAmount(Convert.ToDouble(lblTotalAmount.Text), Convert.ToDouble(rblOffers.SelectedValue));
                discountCommand      = new DiscountCommand(calculateOrderAmount);
                cashBackCommand      = new CashBackCommand(calculateOrderAmount);

                //Cash back offer selected
                if (rblOffers.SelectedIndex == 0)
                {
                    command = cashBackCommand;
                    message = "Cash back of Rs." + command.Execute().ToString() + " will be added to your account!!!";
                    #region Show a message
                    System.Text.StringBuilder sb = new System.Text.StringBuilder();
                    sb.Append("<script type = 'text/javascript'>");
                    sb.Append("window.onload=function(){");
                    sb.Append("alert('");
                    sb.Append(message);
                    sb.Append("')};");
                    sb.Append("</script>");
                    ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", sb.ToString());
                    #endregion
                }
                //Discount Offer Selected
                else if (rblOffers.SelectedIndex == 1)
                {
                    command             = discountCommand;
                    lblTotalAmount.Text = command.Execute().ToString();

                    #region Enable/Disable Controls
                    lblOfferAmount.Text    = lblTotalAmount.Text;
                    lblOfferAmount.Visible = true;

                    lblOfferAmount.Font.Strikeout = true;
                    lblOfferAmount.ForeColor      = System.Drawing.Color.Red;
                    #endregion
                }

                btnApply.Enabled  = false;
                btnRemove.Enabled = true;
            }
        }