Public Class Form1


    Private Sub ImageClicked(ByVal sender As Object, ByVal e As System.EventArgs) Handles picAuto.Click _
        , picHome.Click
        Dim picImageClicked As PictureBox = sender
        Me.grpWhatToKnow.Visible = True
        Me.btnNewLoan.Visible = True
        Me.btnCalculate.Visible = True
        Me.btnCalculate.Enabled = False
        Me.lstTerm.Items.Clear()

        Select Case picImageClicked.Tag
            Case "auto"
                Me.lstTerm.Items.Add("2 years")
                Me.lstTerm.Items.Add("3 years")
                Me.lstTerm.Items.Add("5 years")
                Me.lstTerm.Items.Add("7 years")
            Case "home"
                Me.lstTerm.Items.Add("10 years")
                Me.lstTerm.Items.Add("15 years")
                Me.lstTerm.Items.Add("30 years")
        End Select

    End Sub

    Private Sub btnNewLoan_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnNewLoan.Click
        Me.grpWhatToKnow.Visible = False
        Me.radHowMuch.Checked = False
        Me.radPaymentSize.Checked = False
        Me.lblTermPrompt.Visible = False
        Me.lstTerm.Visible = False
        Me.lblPrincipalOrPaymentPrompt.Visible = False
        Me.txtPrincipalOrPayment.Visible = False
        Me.lblRatePrompt.Visible = False
        Me.cboRate.Visible = False
        Me.btnNewLoan.Visible = False
        Me.btnCalculate.Visible = False
        Me.lblResult.text = Nothing
    End Sub

    Private Sub radPaymentSize_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles radPaymentSize.Click _
        , radHowMuch.Click
        Dim radOptionClicked As RadioButton = sender

        Me.lblTermPrompt.Visible = True
        Me.lstTerm.Visible = True

        Select Case radOptionClicked.Tag
            Case "how much"
                Me.lblPrincipalOrPaymentPrompt.Text = "Desired Payment:"
            Case "payment size"
                Me.lblPrincipalOrPaymentPrompt.Text = "Loan Ammount:"
        End Select
        Me.lblPrincipalOrPaymentPrompt.Visible = True
        Me.txtPrincipalOrPayment.Visible = True
        Me.txtPrincipalOrPayment.Text = Nothing
        Me.lblRatePrompt.Visible = True
        Me.cboRate.Visible = True
        Me.cboRate.Text = Nothing
    End Sub

    Private Sub lstTerm_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles lstTerm.SelectedIndexChanged _
        , txtPrincipalOrPayment.TextChanged, cboRate.SelectedIndexChanged, cboRate.TextChanged
        Me.lblResult.text = Nothing
        Me.btnCalculate.Enabled = False

        If Me.txtPrincipalOrPayment.Text <> Nothing And _
            Me.cboRate.Text <> Nothing Then
            Me.btnCalculate.Enabled = True
        End If
    End Sub

    Private Sub btnCalculate_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
        Dim term As Integer
        Dim principalOrPayment As Decimal
        Dim rate As Double
        Dim result As Decimal
        Dim validData As Boolean
        term = Val(Me.lstTerm.SelectedItem)
        GetDollarAmount(Me.txtPrincipalOrPayment, principalOrPayment, validData)

        If validData Then
            GetPercentAmount(Me.cboRate, rate, validData)
        End If

        If validData Then
            If Me.radHowMuch.Checked Then
                result = PV(rate / 12, term * 12, -principalOrPayment)
                Me.lblResult.Text = "Loan Ammount: " & Format(result, "Currency")
            Else
                result = Pmt(rate / 12, term * 12, -principalOrPayment)
                Me.lblResult.Text = "Payment Ammount: " & Format(result, "Currency")
            End If
        Else
            Me.lblResult.Text = "Data not valid."
        End If
    End Sub
    Sub GetDollarAmount(ByVal txtUserData As TextBox, ByRef dollars As Decimal, _
                        ByRef isValid As Boolean)
        Dim testAmount As String

        isValid = False
        If txtUserData.Text <> Nothing Then
            testAmount = txtUserData.Text
            testAmount = testAmount.Replace("$", "")
            testAmount = testAmount.Replace(",", "")
            If IsNumeric(testAmount) Then
                dollars = Val(testAmount)
                isValid = True
            End If
        End If
    End Sub
    Sub GetPercentAmount(ByVal cboUserData As ComboBox, ByRef percent As Double, _
                         ByRef isValid As Boolean)
        Dim testAmount As String

        isValid = False
        If cboUserData.text <> Nothing Then
            testAmount = cboUserData.text
            testAmount = testAmount.TrimEnd("%")
            If IsNumeric(testAmount) Then
                If Val(testAmount) / 100 Then
                    percent = Val(testAmount) / 100
                Else
                    percent = Val(testAmount)
                End If
                isValid = True
            End If
        End If
    End Sub
End Class