Dim whereToSave As String
Delegate Sub ChangeTextsSafe(ByVal length As Long, ByVal position As Integer, ByVal percent As Integer, ByVal speed As Double)
Delegate Sub DownloadCompleteSafe(ByVal cancelled As Boolean)
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Me.Button3.Enabled = False
Dim theResponse As HttpWebResponse
Dim theRequest As HttpWebRequest
Try
theRequest = WebRequest.Create(Me.TextBox1.Text)
theResponse = theRequest.GetResponse
Catch ex As Exception
MessageBox.Show("An error occurred while downloading file. Possibe causes:" & ControlChars.CrLf & _
"1) File doesn't exist" & ControlChars.CrLf & _
"2) Remote server error", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
Dim cancelDelegate As New DownloadCompleteSafe(AddressOf DownloadComplete)
Me.Invoke(cancelDelegate, True)
Exit Sub
End Try
Dim length As Long = theResponse.ContentLength
Dim safedelegate As New ChangeTextsSafe(AddressOf ChangeTexts)
Me.Invoke(safedelegate, length, 0, 0, 0)
Dim writeStream As New IO.FileStream(Me.whereToSave, IO.FileMode.Create)
Dim nRead As Integer
Dim speedtimer As New Stopwatch
Dim currentspeed As Double = -1
Dim readings As Integer = 0

Do
If BackgroundWorker1.CancellationPending Then
Exit Do
End If
speedtimer.Start()
Dim readBytes(4095) As Byte
Dim bytesread As Integer = theResponse.GetResponseStream.Read(readBytes, 0, 4096)
nRead += bytesread
Dim percent As Short = (nRead / length) * 100
Me.Invoke(safedelegate, length, nRead, percent, currentspeed)

If bytesread = 0 Then Exit Do
writeStream.Write(readBytes, 0, bytesread)
speedtimer.Stop()
readings += 1

If readings >= 5 Then
currentspeed = 20480 / (speedtimer.ElapsedMilliseconds / 1000)
speedtimer.Reset()
readings = 0
End If
Loop

theResponse.GetResponseStream.Close()
writeStream.Close()

If Me.BackgroundWorker1.CancellationPending Then
IO.File.Delete(Me.whereToSave)
Dim cancelDelegate As New DownloadCompleteSafe(AddressOf DownloadComplete)
Me.Invoke(cancelDelegate, True)
Exit Sub
End If

Dim completeDelegate As New DownloadCompleteSafe(AddressOf DownloadComplete)
Me.Invoke(completeDelegate, False)
End Sub

Public Sub DownloadComplete(ByVal cancelled As Boolean)
Me.TextBox1.Enabled = True
Me.Button3.Enabled = True

If cancelled Then
Me.Button5.Enabled = False
Me.label13.Text = "Cancelled"
MessageBox.Show("Download Cancelled !", "Aborted", MessageBoxButtons.OK, MessageBoxIcon.Information)
Else
Me.Button5.Enabled = False
Me.label13.Text = "Successfully downloaded"
MessageBox.Show("Download Succeded !", "Aborted", MessageBoxButtons.OK, MessageBoxIcon.Information)
End If

Me.ProgressBar1.Value = 0
End Sub

Public Sub ChangeTexts(ByVal length As Long, ByVal position As Integer, ByVal percent As Integer, ByVal speed As Double)

Me.label12.Text = Math.Round((length / 1024), 2) & " KB"
Me.label10.Text = Me.TextBox1.Text
Me.label13.Text = Math.Round((position / 1024), 2) & " KB of " & Math.Round((length / 1024), 2) & "KB (" & Me.ProgressBar1.Value & "%)"
Me.Label15.Text = Me.ProgressBar1.Value & "%"
If speed = -1 Then
Me.label14.Text = "calculating..."
Else
Me.label14.Text = Math.Round((speed / 1024), 2) & " KB/s"
End If

Me.ProgressBar1.Value = percent
End Sub

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If TextBox1.Text = "" Then
SaveFileDialog1.Filter = "All File(*.*)--(*.*)"
ElseIf Me.TextBox1.Text.EndsWith(".exe") Then
SaveFileDialog1.Filter = "Setup File(*.exe)--*.exe"
ElseIf Me.TextBox1.Text.EndsWith(".rar") Then
SaveFileDialog1.Filter = "RAR File(*.rar)--*.rar"
ElseIf Me.TextBox1.Text.EndsWith(".zip") Then
SaveFileDialog1.Filter = "ZIP File(*.zip)--*.zip"
ElseIf Me.TextBox1.Text.EndsWith(".pdf") Then
SaveFileDialog1.Filter = "PDF(*.pdf)--*.pdf"
End If
Me.SaveFileDialog1.FileName = Me.TextBox1.Text.Split("/"c)(Me.TextBox1.Text.Split("/"c).Length - 1)
Me.label9.Text = Me.TextBox1.Text.Split("/"c)(Me.TextBox1.Text.Split("/"c).Length - 1)
Me.SaveFileDialog1.ShowDialog()
Me.TextBox2.Text = Me.SaveFileDialog1.FileName
End Sub

Private Sub btDownload_Click(sender As Object, e As EventArgs) Handles Button3.Click
If Me.TextBox1.Text "" AndAlso Me.TextBox1.Text.StartsWith("http://") Then
Me.whereToSave = Me.TextBox2.Text
Me.SaveFileDialog1.FileName = ""
Me.TextBox2.Text = whereToSave
Me.TextBox1.Enabled = False
Me.Button3.Enabled = False
Me.Button5.Enabled = True
Me.TextBox2.Enabled = False
Me.Button1.Enabled = False
Me.BackgroundWorker1.RunWorkerAsync()

Else
MessageBox.Show("This url is not valid", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning)
End If
End Sub

Private Sub btCancel_Click(sender As Object, e As EventArgs) Handles Button5.Click
Me.BackgroundWorker1.CancelAsync()
TextBox2.Enabled = True
Button1.Enabled = True
End Sub

Me.Close()

MsgBox("مقدمة وإهداء من أخوكم ابو فهمي " & vbCrLf & "أتمني ان يحوز علي رضاكم" & vbCrLf & "جميع الحقوق محفوظة " & vbCrLf & "24/1/2015 : تاريخ الإصدار ")