''' <summary>
''' The class that handles the Tilesets.
''' </summary>
''' <remarks></remarks>
Public Class TileSet

    Private _img As Image = Nothing

    Private _tilelist As New List(Of Tiles)
    Private _threadlist As New List(Of Threading.Thread)
    Private _canfinish As Boolean = False
    Private _calculator As New Stopwatch
    Public Event TilesetFinished()

    ''' <summary>
    ''' Stores a tile, with the coordinate on the tileset and the image it is.
    ''' </summary>
    ''' <remarks></remarks>
    Public Structure Tiles
        Public Property X As Integer
        Public Property Y As Integer
        Public Property Img As Image
    End Structure

    ''' <summary>
    ''' Creates a new Tileset Class.
    ''' </summary>
    ''' <param name="tileset">The Image to load.</param>
    ''' <remarks></remarks>
    Public Sub New(ByRef tileset As Image)
        'Check dimensions
        If ValidDimensions(tileset) Then _img = tileset Else Throw New ArgumentException("Invalid Image Dimensions!")
        'Now create the tiles
        Me.CreateTiles(_img)
    End Sub

    ''' <summary>
    ''' Creats a new Tileset Class.
    ''' </summary>
    ''' <param name="filepath">The filepath to the image.</param>
    ''' <remarks></remarks>
    Public Sub New(ByVal filepath As String)
        Me.New(Image.FromFile(filepath))
    End Sub

    ''' <summary>
    ''' Checks the Image for valid base 2 dimensions.
    ''' </summary>
    ''' <param name="img">The image to check for.</param>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Private Function ValidDimensions(ByVal img As Image) As Boolean
        Return img.Width Mod 16 = 0 AndAlso img.Height Mod 16 = 0
    End Function

    ''' <summary>
    ''' Creates the individual pieces for the tileset in a 16 x 16 mini square.
    ''' </summary>
    ''' <param name="tileset">The tileset image to use.</param>
    ''' <remarks></remarks>
    Private Sub CreateTiles(ByRef tileset As Image)
        'Get the number of horizontal squares
        Dim _horizontal As Integer = CInt(tileset.Width / 16)
        Dim _vertical As Integer = CInt(tileset.Height / 16)
        Dim graphics As Graphics = graphics.FromImage(tileset)
        _calculator.Start()
        'x number of columns.
        For hori As Integer = 0 To _horizontal
            Dim imgcopy As Image = CopyImage(tileset)
            'Spin off a thread.
            Dim tr As New Threading.Thread(New Threading.ParameterizedThreadStart(AddressOf CalculateColumn))
            _threadlist.Add(tr)
            tr.Start(New ThreadData With {.HorizontalValue = hori, .img = imgcopy, .graphics = graphics, .ID = tr.ManagedThreadId})
        Next
        _canfinish = True
    End Sub

    ''' <summary>
    ''' Copies an image.
    ''' </summary>
    ''' <param name="img"></param>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Private Function CopyImage(ByRef img As Image) As Image
        Dim MS As New MemoryStream
        img.Save(MS, Imaging.ImageFormat.Png)
        Return Image.FromStream(MS)
    End Function

    Private Structure ThreadData
        Public img As Image
        Public HorizontalValue As Integer
        Public graphics As Graphics
        Public ID As Integer
    End Structure

    ''' <summary>
    ''' Calculuates a series of columns for a tileset.
    ''' </summary>
    ''' <param name="TD2"></param>
    ''' <remarks></remarks>
    Private Sub CalculateColumn(ByVal TD2 As Object)
        Dim TD As ThreadData = CType(TD2, ThreadData)
        Dim _horizontal As Integer = CInt(TD.img.Width / 16)
        Dim _vertical As Integer = CInt(TD.img.Height / 16)
        Dim graphics As Graphics = graphics.FromImage(TD.img)
        Dim bmp As New Bitmap(16I, 16I)
        'x number of rows.
        For verti As Integer = 0 To _vertical

            'Get current square.
            Dim topleft As Point = New Point(TD.HorizontalValue * 16, verti * 16)
            Dim bottomright As Point = New Point(topleft.X + 15, topleft.Y + 15)

            'Create the tile.
            Dim tile As New Tiles
            tile.X = TD.HorizontalValue
            tile.Y = verti

            'Create the bitmap.
            graphics.DrawImage(bmp, New Rectangle(topleft, New Size(bottomright)))

            'Assign it.
            tile.Img = bmp

            _tilelist.Add(tile)

        Next
        Me.ThreadFinished(TD)
    End Sub

    Public ReadOnly Property TileData As List(Of Tiles)
        Get
            Return _tilelist
        End Get
    End Property

    ''' <summary>
    ''' Called when a thread is finished.
    ''' </summary>
    ''' <param name="td">The thread data.</param>
    ''' <remarks></remarks>
    Private Sub ThreadFinished(ByRef td As ThreadData)
        SyncLock _threadlist
            For i As Integer = _threadlist.Count - 1 To 0 Step -1
                If _threadlist(i).ManagedThreadId = td.ID Then _threadlist.RemoveAt(i) : Exit For
            Next
        End SyncLock
        If _threadlist.Count = 0 AndAlso _canfinish Then
            _calculator.Stop()
            System.Windows.Forms.MessageBox.Show(_calculator.Elapsed.TotalSeconds.ToString)
            RaiseEvent TilesetFinished()
        End If
    End Sub

End Class