Public Class Form1
    Dim matchsticks As Integer
    Dim matchsticksLabel As String
    Dim playing As Boolean = False
    Dim playerTurn As Boolean = False

    'Give the Rules of the Game button
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        'Declare a constant so it doesn't fill up the line MsgBox() is on.
        Const rules As String = "The object of this game is to pick up sticks. But, that's not all. Here is how the game is played. You choose the number of matchsticks (from 5 to 40) to place in a pile. Then, the computer will choose who goes first. When your turn comes, you can remove 1 - 3 matchsticks from the pile. The contestant who removes the last matchstick loses."

        'Show the rules to the user
        MsgBox(rules, , "Da Rules")
    End Sub

    'Begin a New Game button
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        If playing Then
            If MsgBox("Do you really want to start a new game?", vbQuestion + vbYesNo) = vbNo Then
                Return
            End If
        End If
        'Constants for min/max sticks
        Const minSticks As Integer = 5
        Const maxSticks As Integer = 40

        'Reset the matchsticks label
        matchsticksLabel = ""

        'Display input box and prompt the user properly.
        If Integer.TryParse(InputBox("How many matchsticks do you want to place in a pile? (A number:" & minSticks.ToString() & " - " & maxSticks.ToString() & ")", "Starting Matchsticks", minSticks), matchsticks) Then
            'The user has entered a valid entry.
            If matchsticks >= minSticks And matchsticks <= maxSticks Then
                playing = True
                For index As Integer = 1 To matchsticks
                    matchsticksLabel += "| "
                Next
                TextBox1.Text = matchsticksLabel

                If (matchsticks Mod 4) = 1 Then
                    playerTurn = True
                    MsgBox("The computer has chosen for you to go first.", , "Player Turn")
                Else
                    playerTurn = False
                    MsgBox("The computer has chosen the be the first to go.", , "Player Turn")
                    CheckIfWon(CInt(Int((3 * Rnd()) + 1)))

                End If
            Else
                'The user has entered a number out of range. Reset the program.
                playing = False
                matchsticks = 0
                TextBox1.Text = matchsticksLabel
                Return
            End If
        End If
    End Sub

    'Remove 1 matchstick
    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        Dim draw As Integer = 1
        If draw > matchsticks Then
            draw = matchsticks
        End If
        matchsticks -= 1
        If Not CheckIfWon(draw) Then
            playerTurn = Not playerTurn
            TextBox1.Text = matchsticksLabel.Substring(0, matchsticks * 2)
            CheckIfWon(CInt(Int((3 * Rnd()) + 1)))
        End If
    End Sub

    'Remove 2 matchstick
    Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
        Dim draw As Integer = 2
        If draw > matchsticks Then
            draw = matchsticks
        End If
        matchsticks -= draw
        If Not CheckIfWon(draw) Then
            playerTurn = Not playerTurn
            TextBox1.Text = matchsticksLabel.Substring(0, matchsticks * 2)
            CheckIfWon(Int((3 * Rnd()) + 1))
        End If
    End Sub

    'Remove 3 matchstick
    Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click
        Dim draw As Integer = 3
        If draw > matchsticks Then
            draw = matchsticks
        End If
        matchsticks -= draw
        If Not CheckIfWon(draw) Then
            playerTurn = Not playerTurn
            TextBox1.Text = matchsticksLabel.Substring(0, matchsticks * 2)
            CheckIfWon(Int((3 * Rnd()) + 1))
        End If
    End Sub

    'Check if the user has one or whether or not they are playing.
    Private Function CheckIfWon(draw As Integer) As Boolean
        'If there are no matchsticks to begin with or they are not playing... do nothing.
        If (draw <= 0) Or (Not playing) Then
            Return True
        End If

        'Whether or not the computer is drawing
        If playerTurn = False Then
            If draw >= matchsticks Then
                If matchsticks <> 1 Then
                    draw = matchsticks - 1
                Else
                    draw = matchsticks
                End If
            End If
            matchsticks -= draw
            TextBox1.Text = matchsticksLabel.Substring(0, matchsticks * 2)
        End If

        'End game results.
        If matchsticks <= 0 Then
            If playerTurn = False Then
                MsgBox("The computer selects " & draw.ToString() & " matchsticks. I win.", , "Hooray")
                Return True
            Else
                MsgBox("I select " & draw.ToString() & " matchsticks. I lose.", , "Boo")
                Return True
            End If
        End If

        'Post game results, whenever any contestant draws.
        If playerTurn = True Then
            MsgBox("I select " & draw.ToString() & "matchsticks. There are " & matchsticks.ToString() & " matchsticks left.", , "Drawing")
        Else
            MsgBox("The computer selects " & draw.ToString() & "matchsticks. There are " & matchsticks.ToString() & " matchsticks left.", , "Drawing")
            playerTurn = Not playerTurn
        End If
        Return False
    End Function
End Class