Install Updates - Native

Function Install-Updates()
{
    [CmdletBinding(SupportsShouldProcess = $true, DefaultParameterSetName = "None")]
    param
    (
        [Parameter(ParameterSetName = "DownloadOnly")]
        [switch] $DownloadOnly,

        [Parameter(ParameterSetName = "InstallOnly")]
        [switch] $InstallOnly,

        [switch] $IncludeHidden
    )

    Function Private:Cleanup
    {
        [void][System.Runtime.InteropServices.Marshal]::ReleaseComObject($session)
        if ($null -ne $updates)
        {
            [void][System.Runtime.InteropServices.Marshal]::ReleaseComObject($updates)
        }
        if ($null -ne $needToDownload)
        {
            [void][System.Runtime.InteropServices.Marshal]::ReleaseComObject($needToDownload)
        }
        if ($null -ne $needToInstall)
        {
            [void][System.Runtime.InteropServices.Marshal]::ReleaseComObject($needToInstall)
        }
    }

    $session = New-Object -ComObject Microsoft.Update.Session
    $searcher = $session.CreateUpdateSearcher()

    $searchStr = "IsInstalled=0 AND IsHidden={0}" -f ([System.Convert]::ToInt32($IncludeHidden.ToBool()))
    $updates = $searcher.Search($searchStr).Updates

    $needToDownload = New-Object -ComObject Microsoft.Update.UpdateColl
    $needToInstall = New-Object -ComObject Microsoft.Update.UpdateColl
    if ($updates.Count -gt 0)
    {
        $displayList = New-Object 'System.Collections.Generic.List[object]' -ArgumentList $updates.Count
        for ($i = 1; $i -le $updates.Count; $i++)
        {
            $update = $updates[$i - 1]
            $displayList.Add([pscustomobject]@{
                    ID         = $i
                    KBArticle  = $update.KBArticleIDs -join ', '
                    Downloaded = $update.IsDownloaded
                    Title      = $update.Title
                })
            if ($update.IsDownloaded)
            {
                [void] $needToInstall.Add($update)
            }
            else
            {
                [void] $needToDownload.Add($update)
            }
        }
    }
    else
    {
        Write-Host "No updates are needed." -f Green
        return
    }

    Write-Host $($displayList | Sort-Object KBArticle | Out-String) -f Cyan

    if ($PSCmdlet.ShouldProcess(("Number of updates: {0}" -f $updates.Count), "Process updates"))
    {
        if ($needToDownload.Count -gt 0 -and -not $InstallOnly)
        {
            Write-Host "`nDownloading updates that haven't yet..." -f Yellow -NoNewline
            $downloader = $session.CreateUpdateDownloader()
            $downloader.Updates = $needToDownload
            $result = $downloader.Download()
            if (-not (($result.Hresult -eq 0) -and ($result.ResultCode -eq 2)))
            {
                Write-Host "FAIL" -f Red
                Write-Error "Updates could not be downloaded." -Category InvalidResult
            }
            else
            {
                Write-Host "DONE!" -f Green
                for ($u = 0; $u -lt @($downloader.Updates).Count; $u++)
                {
                    $dlup = $downloader.Updates.Item($u)
                    [void] $needToInstall.Add($dlup)
                }
            }
            Start-Sleep -Seconds 2
        }

        if ($needToInstall.Count -gt 0 -and -not $DownloadOnly)
        {
            Write-Host "Installing updates..." -f Yellow -NoNewline
            $installer = $session.CreateUpdateInstaller()
            $installer.Updates = $needToInstall
            $installResult = $installer.Install();
            if (-not ($installResult.Hresult -eq 0) -and ($installResult.ResultCode -eq 2))
            {
                Write-Host "DONE!" -f Green
            }
            else
            {
                Write-Host "FAIL" -f Red
                Write-Error ("Failed to install updates.  Error Code: {0}" -f $installResult.Hresult) -Category InvalidResult
            }
            if ($installResult.RebootRequired)
            {
                Write-Warning "A reboot is required to finish the installation."
            }
        }
    }
    Private:Cleanup
}