'Program: Chapter 9 HandsOn
'Programmer: Paul Bock
'Date: 9/28/2012
'Page: Default
'Description: A Web site to calculate the extended price for books sold,
'             a discount, and the discounted amount. Calculates and displays the total discounts.
'             Uses validator controls for input validation.

Partial Class Webform1

    Inherits System.Web.UI.Page

    Private DiscountTotalDecimal As Decimal
    Const DISCOUNT_RATE_Decimal As Decimal = 0.15D

    Sub SubmitButton_Click(ByVal sender As Object,
                           ByVal e As System.EventArgs) Handles SubmitButton.Click
        'Calculate values for sale.
        Dim QuantityInteger As Integer
        Dim PriceDecimal, ExtendedPriceDecimal As Decimal
        Dim DiscountDecimal, DiscountedPriceDecimal As Decimal

        ErrorMessageLabel.Text = String.Empty
        Try
            ' Convert input values to numeric variables.
            QuantityInteger = Integer.Parse(QuantityTextBox.Text)
            PriceDecimal = Decimal.Parse(PriceTextBox.Text)

            ' Calculate values for sale.
            ExtendedPriceDecimal = QuantityInteger * PriceDecimal
            DiscountDecimal = ExtendedPriceDecimal * DISCOUNT_RATE_Decimal
            DiscountedPriceDecimal = ExtendedPriceDecimal - DiscountDecimal

            'Add to the discount total.
            DiscountTotalDecimal += DiscountDecimal

            ' Save the discount total in a label.
            DiscountHiddenField.Value = DiscountTotalDecimal.ToString()

            ' Format and display answers.
            ExtendedPriceTextBox.Text = ExtendedPriceDecimal.ToString("C")
            DiscountTextBox.Text = DiscountDecimal.ToString("N")
            DiscountPriceTextBox.Text = DiscountedPriceDecimal.ToString("C")
        Catch ex As Exception
            ErrorMessageLabel.Text = "Unable to calculate. Check for numeric values."

        End Try

    End Sub

    Private Sub ClearButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles ClearButton.Click
        ' Clear previous amounts from the page.

        QuantityTextBox.Text = " "
        TitleTextBox.Text = " "
        PriceTextBox.Text = " "
        ExtendedPriceTextBox.Text = " "
        DiscountTextBox.Text = " "
        DiscountTotalLabel.Text = " "
        ErrorMessageLabel.Text = " "

    End Sub

    Sub Page_Load(ByVal sender As Object,
                  ByVal e As System.EventArgs) Handles Me.Load
        ' Check for existing value for the discount total

        With DiscountHiddenField
            If IsPostBack And .Value <> " " Then
                DiscountTotalDecimal = Decimal.Parse(.Value)
            End If
        End With
    End Sub

    Private Sub SummaryButton_Click(ByVal sender As Object,
                                    ByVal e As System.EventArgs) Handles SummaryButton.Click
        ' Display the total discount.

        DiscountTotalLabel.Text = "Total Discounts:" & DiscountTotalDecimal.ToString("C")

    End Sub

    Protected Overrides Sub Finalize()
        MyBase.Finalize()
    End Sub
End Class