Проверка состояния скачивания командлетом Invoke-WebRequest

Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
 
$form = New-Object System.Windows.Forms.Form
$form.Text = 'Status Server'
$form.Size = New-Object System.Drawing.Size(350,500)
$form.BackColor = "0x7AC5E7"
$form.Opacity = 0.96
$form.FormBorderStyle = [System.Windows.Forms.FormBorderStyle]::SizableToolWindow
$form.StartPosition = 'CenterScreen'
 
$file = New-TemporaryFile
 
$eventHandler = [System.EventHandler]{
$textBox.Text
$listbox.Items.Add
$url = $textBox.Text
(Invoke-WebRequest -Uri $url).RawContent | Out-File $file.FullName
Get-Content $file.FullName | ForEach-Object {[Void]$listbox.Items.Add($_)}
 
}
 
$eventHandler2 = [System.EventHandler]{
start-process -filepath 'C:\Windows\System32\notepad.exe' -argumentlist $file.FullName
Start-Sleep -Milliseconds 300
$form.Close()
}
 
$eventHandler3 = [System.EventHandler]{
$listBox.Items.Clear()
$textBox.Clear()
Remove-Item $file.FullName -errorAction silentlycontinue
}
 
$OKButton = New-Object System.Windows.Forms.Button
$OKButton.Location = New-Object System.Drawing.Point(10,420)
$OKButton.Size = New-Object System.Drawing.Size(75,23)
$OKButton.Anchor = "Top, Right"
$OKButton.Text = 'OK'
$OKButton.Add_Click($eventHandler)
$form.Controls.Add($OKButton)
 
$LButton = New-Object System.Windows.Forms.Button
$LButton.Location = New-Object System.Drawing.Point(170,420)
$LButton.Size = New-Object System.Drawing.Size(75,23)
$LButton.Anchor = "Top, Right"
$LButton.Text = 'Clear'
$LButton.Add_Click($eventHandler3)
$form.Controls.Add($LButton)
 
$NButton = New-Object System.Windows.Forms.Button
$NButton.Location = New-Object System.Drawing.Point(250,420)
$NButton.Size = New-Object System.Drawing.Size(75,23)
$NButton.Anchor = "Top, Right"
$NButton.Text = 'Notepad'
$NButton.Add_Click($eventHandler2)
$form.Controls.Add($NButton)
 
$CancelButton = New-Object System.Windows.Forms.Button
$CancelButton.Location = New-Object System.Drawing.Point(90,420)
$CancelButton.Size = New-Object System.Drawing.Size(75,23)
$CancelButton.Anchor = "Top, Right"
$CancelButton.Text = 'Cancel'
$CancelButton.Add_click({$form.close()})
$form.Controls.Add($CancelButton)
 
$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Point(10,20)
$label.Size = New-Object System.Drawing.Size(280,20)
$label.Text = 'Вставьте ссылку:'
$form.Controls.Add($label)
 
$textBox = New-Object "System.Windows.Forms.TextBox"
$textBox.Location = New-Object System.Drawing.Point(10,40)
$textBox.Size = New-Object System.Drawing.Size(315,20)
$textBox.Anchor = 'Top, Left, Right'
$textBox.width = 315;
$form.Controls.Add($textBox)
 
$listbox = New-Object System.Windows.Forms.ListBox
$listbox.DisplayMember = $tmp.FullName
$listbox.Name = "listbox"
$listbox.Location = New-Object System.Drawing.Point(10,75)
$listbox.Size = New-Object System.Drawing.Size(315,330)
$listbox.Anchor = "Top, Bottom, Left, Right"
$listbox.Height = 330
 
$form.Controls.Add($listbox)
 
$form.Topmost = $true
 
$form.Add_Shown({$textBox.Select()})
$form.Add_Shown({$listbox.Select()})
$form.ShowDialog()
Remove-Item $file.FullName -errorAction silentlycontinue