CarPark Revised

Module Module1
    Function Modulus11(FrequentNumber As String) As Boolean
        Dim WeightingFactor As Integer
        Dim Checksum As Integer
        For i = 2 To 5
            WeightingFactor = i * Convert.ToInt32(Convert.ToString(FrequentNumber(5 - i)))
            Checksum += WeightingFactor
        Next
        Checksum = 11 - (Checksum Mod 11)
        If Checksum = Convert.ToInt32(Right(FrequentNumber, 1)) Then
            Return True
        Else
            Return False
        End If
    End Function
    Sub Main()
        Dim DayEnd As Boolean
        Dim Day As String
        Dim ArrivalHour As Integer
        Dim NumberHours As Integer
        Dim InvalidHours As Boolean
        Dim HourlyRate As Integer

        Dim ParkingPrice As Double
        Dim ParkingPayment As Double
        Dim FrequentDiscount As Integer
        Dim FrequentNumber As String
        Dim DayTotal As Double
        Dim DayNames As New List(Of String)(New String() {"sunday",
                                            "monday",
                                            "tuesday",
                                            "wednesday",
                                            "thursday",
                                            "friday",
                                            "saturday"})

        Do
            Console.Clear()
            Do
                Console.Write("Enter the day: ") : Day = Console.ReadLine.ToLower
            Loop Until DayNames.Contains(Day)
            Do
                Console.Write("Enter the hour of arrival (8 to 23): ") : ArrivalHour = Console.ReadLine()
            Loop Until ArrivalHour > 7 And ArrivalHour < 24
            If ArrivalHour < 16 Then
                Console.WriteLine("Price per hour:" & Environment.NewLine & "Sunday : £2; Saturday : £3; Rest £10")
                Console.WriteLine("Max parking hours:" & Environment.NewLine & "Sunday : 8 hours; Saturday : 4 hours; Rest 2 hours")
            Else
                Console.WriteLine("Parking upto midnight, £2/hour")
            End If
            Do
                Console.Write("Enter the number of hours you would like to park your car: ") : NumberHours = Console.ReadLine()
                InvalidHours = True
                If ArrivalHour < 16 Then
                    Select Case Day
                        Case "sunday"
                            If NumberHours <= 8 Then
                                InvalidHours = False
                                HourlyRate = 2
                            End If
                        Case "saturday"
                            If NumberHours <= 4 Then
                                InvalidHours = False
                                HourlyRate = 3
                            End If
                        Case Else
                            If NumberHours <= 2 Then
                                InvalidHours = False
                                HourlyRate = 10
                            End If
                    End Select
                    If NumberHours < 0 Then
                        InvalidHours = True
                    End If
                Else
                    If NumberHours <= 24 - ArrivalHour And NumberHours > 0 Then
                        InvalidHours = False
                        HourlyRate = 2
                    End If
                End If
                ParkingPrice = HourlyRate * NumberHours
            Loop While InvalidHours
            If ArrivalHour < 16 And ArrivalHour + NumberHours > 16 Then
                ParkingPrice = (16 - ArrivalHour) * HourlyRate + 2
            End If
            FrequentDiscount = 0
            Console.WriteLine("Enter 'True' if you have a valid frequent parking number to avail a discount")
            Console.WriteLine("If not applicable, Enter False")
            Console.Write(">")
            If Console.ReadLine() Then
                Console.Write("Enter your frequent parking number (XXXXX): ") : FrequentNumber = Console.ReadLine()
                If Modulus11(FrequentNumber) Then
                    Console.WriteLine("Discount Valid!")
                    If ArrivalHour < 16 Then
                        FrequentDiscount = 10
                    Else
                        FrequentDiscount = 50
                    End If
                Else
                    Console.WriteLine("Your frequent parking number is invalid.")
                End If
            End If
            ParkingPrice = ParkingPrice * (100 - FrequentDiscount) / 100
            Console.WriteLine("Your bill is £" & ParkingPrice & " after a discount of " & FrequentDiscount & "%")
            Do
                Console.Write("Enter the amount paid(more than or equal to bill): ")
                ParkingPayment = Console.ReadLine
            Loop Until ParkingPayment >= ParkingPrice
            DayTotal += ParkingPayment
            Console.Write("Enter -1 to end the day: ")
            If Console.ReadLine() = -1 Then
                DayEnd = True
            End If
        Loop Until DayEnd
        Console.WriteLine("The daily total of payments: " & DayTotal)
        Console.ReadLine()
    End Sub

End Module