Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    Friend WithEvents TxbPrevReading As System.Windows.Forms.TextBox
    Friend WithEvents TxbCurrReading As System.Windows.Forms.TextBox
    Friend WithEvents Calculate As System.Windows.Forms.Button
    Friend WithEvents Button2 As System.Windows.Forms.Button
    Friend WithEvents LblKWH As System.Windows.Forms.Label
    Friend WithEvents Lblcharge As System.Windows.Forms.Label
    Friend WithEvents Lbltotal As System.Windows.Forms.Label
    Friend WithEvents Lblsalestax As System.Windows.Forms.Label
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents Label3 As System.Windows.Forms.Label
    Friend WithEvents Label4 As System.Windows.Forms.Label
    Friend WithEvents Label5 As System.Windows.Forms.Label
    Friend WithEvents Label6 As System.Windows.Forms.Label
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.TxbPrevReading = New System.Windows.Forms.TextBox
        Me.TxbCurrReading = New System.Windows.Forms.TextBox
        Me.Calculate = New System.Windows.Forms.Button
        Me.Button2 = New System.Windows.Forms.Button
        Me.LblKWH = New System.Windows.Forms.Label
        Me.Lblcharge = New System.Windows.Forms.Label
        Me.Lbltotal = New System.Windows.Forms.Label
        Me.Lblsalestax = New System.Windows.Forms.Label
        Me.Label1 = New System.Windows.Forms.Label
        Me.Label2 = New System.Windows.Forms.Label
        Me.Label3 = New System.Windows.Forms.Label
        Me.Label4 = New System.Windows.Forms.Label
        Me.Label5 = New System.Windows.Forms.Label
        Me.Label6 = New System.Windows.Forms.Label
        Me.SuspendLayout()
        '
        'TxbPrevReading
        '
        Me.TxbPrevReading.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.TxbPrevReading.Location = New System.Drawing.Point(32, 48)
        Me.TxbPrevReading.Name = "TxbPrevReading"
        Me.TxbPrevReading.TabIndex = 0
        Me.TxbPrevReading.Text = ""
        '
        'TxbCurrReading
        '
        Me.TxbCurrReading.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.TxbCurrReading.Location = New System.Drawing.Point(32, 96)
        Me.TxbCurrReading.Name = "TxbCurrReading"
        Me.TxbCurrReading.TabIndex = 1
        Me.TxbCurrReading.Text = ""
        '
        'Calculate
        '
        Me.Calculate.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Calculate.Location = New System.Drawing.Point(168, 32)
        Me.Calculate.Name = "Calculate"
        Me.Calculate.Size = New System.Drawing.Size(88, 23)
        Me.Calculate.TabIndex = 2
        Me.Calculate.Text = "&Calculate"
        '
        'Button2
        '
        Me.Button2.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Button2.Location = New System.Drawing.Point(168, 88)
        Me.Button2.Name = "Button2"
        Me.Button2.Size = New System.Drawing.Size(88, 23)
        Me.Button2.TabIndex = 3
        Me.Button2.Text = "E&xit."
        '
        'LblKWH
        '
        Me.LblKWH.BackColor = System.Drawing.SystemColors.Info
        Me.LblKWH.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.LblKWH.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.LblKWH.Location = New System.Drawing.Point(160, 152)
        Me.LblKWH.Name = "LblKWH"
        Me.LblKWH.TabIndex = 4
        Me.LblKWH.TextAlign = System.Drawing.ContentAlignment.MiddleCenter
        '
        'Lblcharge
        '
        Me.Lblcharge.BackColor = System.Drawing.SystemColors.Info
        Me.Lblcharge.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.Lblcharge.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Lblcharge.Location = New System.Drawing.Point(160, 184)
        Me.Lblcharge.Name = "Lblcharge"
        Me.Lblcharge.TabIndex = 5
        Me.Lblcharge.TextAlign = System.Drawing.ContentAlignment.MiddleRight
        '
        'Lbltotal
        '
        Me.Lbltotal.BackColor = System.Drawing.SystemColors.Info
        Me.Lbltotal.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.Lbltotal.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Lbltotal.Location = New System.Drawing.Point(160, 248)
        Me.Lbltotal.Name = "Lbltotal"
        Me.Lbltotal.TabIndex = 6
        Me.Lbltotal.TextAlign = System.Drawing.ContentAlignment.MiddleRight
        '
        'Lblsalestax
        '
        Me.Lblsalestax.BackColor = System.Drawing.SystemColors.Info
        Me.Lblsalestax.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.Lblsalestax.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Lblsalestax.Location = New System.Drawing.Point(160, 216)
        Me.Lblsalestax.Name = "Lblsalestax"
        Me.Lblsalestax.TabIndex = 7
        Me.Lblsalestax.TextAlign = System.Drawing.ContentAlignment.MiddleRight
        '
        'Label1
        '
        Me.Label1.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.Label1.Location = New System.Drawing.Point(24, 216)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(120, 23)
        Me.Label1.TabIndex = 11
        Me.Label1.Text = " Sales Tax:"
        Me.Label1.TextAlign = System.Drawing.ContentAlignment.MiddleLeft
        '
        'Label2
        '
        Me.Label2.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.Label2.Location = New System.Drawing.Point(24, 248)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(120, 23)
        Me.Label2.TabIndex = 10
        Me.Label2.Text = " Total Bill:"
        Me.Label2.TextAlign = System.Drawing.ContentAlignment.MiddleLeft
        '
        'Label3
        '
        Me.Label3.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.Label3.Location = New System.Drawing.Point(24, 184)
        Me.Label3.Name = "Label3"
        Me.Label3.Size = New System.Drawing.Size(120, 23)
        Me.Label3.TabIndex = 9
        Me.Label3.Text = " Electricity Consumed:"
        Me.Label3.TextAlign = System.Drawing.ContentAlignment.MiddleLeft
        '
        'Label4
        '
        Me.Label4.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.Label4.Location = New System.Drawing.Point(24, 152)
        Me.Label4.Name = "Label4"
        Me.Label4.Size = New System.Drawing.Size(120, 23)
        Me.Label4.TabIndex = 8
        Me.Label4.Text = " KWH Consumed:"
        Me.Label4.TextAlign = System.Drawing.ContentAlignment.MiddleLeft
        '
        'Label5
        '
        Me.Label5.Location = New System.Drawing.Point(24, 24)
        Me.Label5.Name = "Label5"
        Me.Label5.Size = New System.Drawing.Size(128, 24)
        Me.Label5.TabIndex = 12
        Me.Label5.Text = "Previous Meter Reading"
        Me.Label5.TextAlign = System.Drawing.ContentAlignment.MiddleLeft
        '
        'Label6
        '
        Me.Label6.Location = New System.Drawing.Point(24, 72)
        Me.Label6.Name = "Label6"
        Me.Label6.Size = New System.Drawing.Size(128, 24)
        Me.Label6.TabIndex = 13
        Me.Label6.Text = "Current Meter Reading"
        Me.Label6.TextAlign = System.Drawing.ContentAlignment.MiddleLeft
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 293)
        Me.Controls.Add(Me.TxbCurrReading)
        Me.Controls.Add(Me.TxbPrevReading)
        Me.Controls.Add(Me.Label6)
        Me.Controls.Add(Me.Label5)
        Me.Controls.Add(Me.Label1)
        Me.Controls.Add(Me.Label2)
        Me.Controls.Add(Me.Label3)
        Me.Controls.Add(Me.Label4)
        Me.Controls.Add(Me.Lblsalestax)
        Me.Controls.Add(Me.Lbltotal)
        Me.Controls.Add(Me.Lblcharge)
        Me.Controls.Add(Me.LblKWH)
        Me.Controls.Add(Me.Button2)
        Me.Controls.Add(Me.Calculate)
        Me.Name = "Form1"
        Me.Text = "  Electric Bill"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Me.Close()
    End Sub


    Private Sub Txb_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TxbCurrReading.KeyPress, TxbPrevReading.KeyPress
        If (e.KeyChar < "0" OrElse e.KeyChar > "9") AndAlso e.KeyChar <> ControlChars.Back Then
            e.Handled = True
        End If
        If e.KeyChar = ControlChars.Cr Then
            If Me.TxbPrevReading.Text <> "" AndAlso Me.TxbCurrReading.Text <> "" Then
                Me.Calculate.PerformClick()
            Else
                Me.TxbCurrReading.Focus()
            End If
        End If
    End Sub

    Private Sub Calculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Calculate.Click
        Dim electricityCharge, salesTax As Double
        Dim previousMeterReading, currentMeterReading, kwhConsumed As Integer
        If Me.TxbCurrReading.Text <> "" AndAlso Me.TxbPrevReading.Text <> "" Then
            currentMeterReading = Me.TxbCurrReading.Text
            previousMeterReading = Me.TxbPrevReading.Text
            kwhConsumed = currentMeterReading - previousMeterReading
            If kwhConsumed < 0 Then
                MsgBox(" The Current Meter Reading have to be greater than the Previous", MsgBoxStyle.Critical, " Wrong entry")
                Me.TxbCurrReading.SelectAll()
            Else
                electricityCharge = ComputeElectricityCharge(kwhConsumed)
                salesTax = ComputeSalesTax(electricityCharge)
                Me.Lblcharge.Text = Format(electricityCharge, "currency")
                Me.LblKWH.Text = kwhConsumed
                Me.Lblsalestax.Text = Format(salesTax, "currency")
                Me.Lbltotal.Text = Format(salesTax + electricityCharge, "currency")
                Me.TxbCurrReading.Focus()
            End If
        End If
    End Sub
    Private Function ComputeElectricityCharge(ByVal kwh As Integer) As Double
        Dim amount As Double
        Select Case kwh
            Case Is < 500
                amount = kwh * 0.05
            Case 500 To 1000
                amount = 25 + (kwh - 500) * 0.055
            Case Is > 1000
                amount = 52.5 + (kwh - 1000) * 0.06
        End Select
        amount = Math.Round(amount, 2)
        Return amount
    End Function

    Public Function ComputeSalesTax(ByVal amount As Double) As Double
        Const SALES_TAX_RATE As Double = 0.085
        Dim salesTax As Double
        salesTax = SALES_TAX_RATE * amount
        salesTax = Math.Round(salesTax, 2)
        Return salesTax
    End Function
End Class