Option Explicit On
Option Strict On

Public Class Form1

    Dim numbers(100) As Double
    Dim compared(100) As Double ' compared to average
    Dim sorted(100) As Double
    Dim numItems As Integer

    Private Function ExtractLine(ByVal text As String, ByRef line As String, ByRef startPos As Integer, ByRef foundPos As Integer) As Boolean
        ' find the next occurrence of the new line char
        foundPos = text.IndexOf(ControlChars.NewLine, startPos)
        ' check if it was found
        If foundPos = -1 Then
            Return False
        Else
            ' pull out the current line of the file
            line = text.Substring(startPos, foundPos - startPos)
            ' update the starting point for search
            startPos = foundPos + 2
            Return True
        End If
    End Function

    ' general function to calculate mean of any array of doubles
    Private Function CalcAverage(ByVal data() As Double, ByVal numOfItems As Integer) As Double

        Dim total As Double
        Dim ave As Double

        Dim cnt As Integer
        For cnt = 0 To numOfItems - 1
            total = total + data(cnt)

        Next cnt
        ave = total / numItems
        Return ave
    End Function


    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim allText As String
        Dim lineExists As Boolean
        Dim current As String
        Dim start As Integer = 0
        Dim foundPos As Integer

        ' check if file exists
        If My.Computer.FileSystem.FileExists("numbers.txt") Then

            ' read the file contents
            allText = My.Computer.FileSystem.ReadAllText("numbers.txt")

            ' while not at end, extract line
            Do
                lineExists = ExtractLine(allText, current, start, foundPos)
                If lineExists Then
                    ' stick the line in the list box
                    rtbData.AppendText(current & ControlChars.NewLine)
                    Dim isConverted As Boolean
                    isConverted = Double.TryParse(current, numbers(numItems))
                    If isConverted Then
                        numItems = numItems + 1
                    End If

                End If
            Loop While lineExists
        Else
            MsgBox("Please put the numbers.txt file in the bin folder for the project")
        End If

    End Sub

    Private Sub btnHowMany_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnHowMany.Click

        Dim threshold As Double
        Dim isConverted As Boolean
        Dim numAbove As Integer
        ' convert threshold to number
        isConverted = Double.TryParse(txtThreshold.Text, threshold)
        If isConverted Then
            ' loop through the array finding out how many are larger than the threshold

            Dim cnt As Integer
            For cnt = 0 To numItems - 1
                ' just for fun
                'MsgBox("Current number is: " & numbers(cnt).ToString)

                ' figure out if numberr is above threshold
                If numbers(cnt) > threshold Then
                    ' is above threshold
                    numAbove = numAbove + 1
                End If

            Next cnt
            txtAnswer.Text = numAbove.ToString
        End If
    End Sub


    Private Sub btnAve_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAve.Click

        Dim ave As Double
        ave = CalcAverage(numbers, numItems)
        TxtAve.Text = ave.ToString("n2")

    End Sub

    Private Sub btnMax_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnMax.Click
        Dim max As Double = -9999999999

        For cnt As Integer = 0 To numItems - 1
            If numbers(cnt) > max Then
                max = numbers(cnt)
            End If
        Next cnt
        txtMax.Text = max.ToString

    End Sub

    ' display for each element in array its difference from the average
    Private Sub btnCompareToAve_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCompareToAve.Click
        Dim ave As Double
        ave = CalcAverage(numbers, numItems)

        ' illegal example
        ' compared = numbers - ave

        Dim cnt As Integer
        ' set compared to compare to average
        For cnt = 0 To numItems - 1
            compared(cnt) = numbers(cnt) - ave
        Next cnt


        ' display comparisons in rich text box
        For cnt = 0 To numItems - 1
            rtbCompared.AppendText(compared(cnt) & ControlChars.NewLine)
        Next cnt
    End Sub

    Private Sub btnSort_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSort.Click

        Dim cnt As Integer
        sorted = numbers
        Array.Sort(sorted)
        Array.Reverse(sorted)
        ' display comparisons in rich text box
        For cnt = 0 To numItems - 1
            rtbSorted.AppendText(sorted(cnt) & ControlChars.NewLine)
        Next cnt
    End Sub

    Private Sub btnSortAsc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSortAsc.Click

        rtbSorted.Clear()
        Dim cnt As Integer
        sorted = numbers
        Array.Sort(sorted)
        ' display comparisons in rich text box
        For cnt = 100 - (numItems - 1) To 100
            rtbSorted.AppendText(sorted(cnt) & ControlChars.NewLine)
        Next cnt
    End Sub
End Class