param (
    [parameter( Mandatory = $true )][string]$OrganizationalUnit,
    [psobject]$Script = ( Get-Content -Path "$PSScriptRoot\update.ps1" ),
    [int]$Threads = 64
)

$Credential = Get-Credential
$UserName = $Credential.UserName
$Password = $Credential.GetNetworkCredential().Password

function Export-ServerList
{
    param (
        [string]$OrganizationalUnit
    )

    $ServerList = dsquery.exe computer $OrganizationalUnit -o rdn -limit 0
    for ( $i = 0; $i -lt $ServerList.Count; $i++ )
    {
        $ServerList[$i] =  $ServerList[$i] -replace '"', ''
    }

    return $ServerList
}

function Run-Schdule
{
    param (
        [string]$ComputerName
    )

    Invoke-Command -ComputerName $ComputerName -ScriptBlock {
        param (
            [psobject]$Script,
            [string]$UserName,
            [string]$Password
        )

        $Script | Out-File -FilePath $env:SystemRoot\System32\update.ps1 -Force

        schtasks.exe /Create /TN WindowsUpdate /TR "powershell.exe -ExecutionPolicy Bypass -File update.ps1" `
            /SC Daily /ST 02:00 /RU $UserName /RP $Password /F
    } -ArgumentList $Script, $UserName, $Password
}

Write-Host "Step 1: Exporting server list..."
$ServerList = Export-ServerList -OrganizationalUnit $OrganizationalUnit

Write-Host "Step 2: Running jobs in parallel..."
$ServerList | Invoke-Parallel -ThrottleLimit $Threads -ScriptBlock {
    Run-Schdule -ComputerName $_
}

Write-Host "finished."