function InstallationResultToText($result) {
  switch ($result) {
    2 { "Succeeded" }
    3 { "Succeeded with errors" }
    4 { "Failed" }
    5 { "Cancelled" }
    default { "Unexpected ($result)" }  
  }
}

Write-Host "--- Running Windows Update ---"
Write-Host "Searching for updates..."
Write-Host ""
$updateSession = new-object -com "Microsoft.Update.Session"
$updateSearcher = $updateSession.CreateupdateSearcher()
$criteria = "IsInstalled=0 and Type='Software' and IsHidden=0"
$searchResult = $updateSearcher.Search($criteria)

Write-Host "List of applicable items on the machine:"

if ($searchResult.Updates.Count -eq 0) {
  Write-Host "There are no applicable updates."
  exit 0
} else {
  $downloadReq = $False
  $i = 0
  foreach ($update in $searchResult.Updates){
    $i++
    if ( $update.IsDownloaded ) {
      Write-Host $i">" $update.Title "(downloaded)"
    } else {
      $downloadReq = $true
      Write-Host $i">" $update.Title "(not downloaded)"
    }
  }
}

if ( $downloadReq ) {
  Write-Host ""
  Write-Host "Creating collection of updates to download..."
  $updatesToDownload = new-object -com "Microsoft.Update.UpdateColl"
  foreach ($update in $searchResult.Updates){
    $updatesToDownload.Add($update) | out-null
  }
  Write-Host "Downloading updates..."
  $downloader = $updateSession.CreateUpdateDownloader()
  $downloader.Updates = $updatesToDownload
  $downloader.Download()
  Write-Host "List of downloaded updates:"
  $i = 0
  foreach ($update in $searchResult.Updates){
    $i++
    if ( $update.IsDownloaded ) {
      Write-Host $i">" $update.Title "(downloaded)"
    } else {
      Write-Host $i">" $update.Title "(not downloaded)"
    }
  }
} else {
  Write-Host "All updates are already downloaded."
}

$updatesToInstall = new-object -com "Microsoft.Update.UpdateColl"
Write-Host ""
Write-Host "Creating collection of downloaded updates to install..."
foreach ($update in $searchResult.Updates){
  if ( $update.IsDownloaded ) {
    $updatesToInstall.Add($update) | out-null
  }
}
$returnValue = 0
if ( $updatesToInstall.Count -eq 0 ) {
  Write-Host "Not ready for installation."
} else {
  Write-Host "Installing" $updatesToInstall.Count "updates..."
  $installer = $updateSession.CreateUpdateInstaller()
  $installer.Updates = $updatesToInstall
  $installationResult = $installer.Install()
  if ( $installationResult.ResultCode -eq 2 ) {
    Write-Host "All updates installed successfully."
  } else {
    Write-Host "Some updates could not installed."
  }
  $returnValue = $installationResult.ResultCode
  if ( $installationResult.RebootRequired ) {
    Write-Host "One or more updates are requiring reboot."
    $returnValue = $returnValue + 100
  } else {
     Write-Host "Finished. Reboot are not required."
  }
  Write-Host ""
  Write-Host "Listing of updates installed and indivisual installation results:"
  $i = 0
  foreach ($update in $updatesToInstall){
    $result = $installationResult.GetUpdateResult($i)
    $i++
    Write-Host $i">" $update.Title ":" $(InstallationResultToText $result.ResultCode) ", HRESULT:" $($result.HResult)
  }
}
Exit $returnValue