'    Program: Gas Prices
'             Enter the gas prices, then on button click
'             determine highest, lowest, or average


Public Class GasPrice
    Dim listArray(11) As Decimal
    Dim counter As Integer = 0

    ' Enter button
    Private Sub btnEnter_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEnter.Click
        ModifyArray(txtInput.Text) ' pass to array
        txtInput.Clear()
        txtInput.Focus()
    End Sub

    ' Pass to array function
    Sub ModifyArray(ByVal arrayElement As Decimal)
        listArray(counter) = arrayElement
        counter += 1
        lstOutput.Items.Add(arrayElement)

        If counter > listArray.GetUpperBound(0) Then ' Button disable
            btnEnter.Enabled = False
        End If
    End Sub

    ' Highest price button
    Private Sub btnHighestPrice_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnHighestPrice.Click
        Array.Sort(listArray)
        Dim index As Decimal = -1
        Dim max As Decimal = listArray(0)

        For i = 0 To listArray.GetUpperBound(0)
            If (listArray(i) > max) Then
                max = listArray(i)
                index = i
            End If
        Next
        lblAnswer.Text = "Highest price: $" & max & " in month " & index
    End Sub

    ' Lowest price button
    Private Sub btnLowestPrice_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLowestPrice.Click
        Array.Sort(listArray)
        Dim index As Decimal = 0
        Dim min As Decimal = listArray(0)

        For i = 0 To listArray.GetUpperBound(0)
            If (listArray(i) < min) Then
                min = listArray(i)
                index = i
            End If
        Next
        lblAnswer.Text = "Lowest price: $" & min & " in month " & index
    End Sub

    ' Average price button
    Private Sub btnAveragePrice_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAveragePrice.Click
        Dim counter As Decimal
        Dim total As Decimal = 0
        Dim average As Decimal

        For counter = 0 To UBound(listArray)
            total = total + listArray(counter)
        Next
        average = total / UBound(listArray)
        lblAnswer.Text = "Average price: $" & average
    End Sub
End Class