$ErrorActionPreference = 'Stop'

$outDir = 'C:\install\missing_updates'
if (-not (Test-Path $outDir)) {
    New-Item -Path $outDir -ItemType Directory -Force | Out-Null
}
$logFile = Join-Path $outDir 'missing_updates.txt'
if (Test-Path $logFile) { Remove-Item $logFile -Force }

function Log {
    param([string]$Text)
    Write-Host $Text
    Add-Content -Path $logFile -Value $Text
}

Log "Online WU scan (buiten WSUS om) - $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss')"
Log "Server: $env:COMPUTERNAME"
Log ('=' * 70)

# --- Online scan tegen Microsoft Update, WSUS negeren ---
Log ""
Log "Scannen tegen Microsoft Update (kan een paar minuten duren)..."
$session  = New-Object -ComObject Microsoft.Update.Session
$searcher = $session.CreateUpdateSearcher()
$searcher.ServerSelection = 3   # ssOthers = expliciet niet WSUS
$searcher.ServiceID = '7971f918-a847-4430-9279-4a52d1efe18d'  # Microsoft Update

$result = $searcher.Search("IsInstalled=0 AND Type='Software' AND IsHidden=0")

$count = $result.Updates.Count
Log "Aantal ontbrekende updates gevonden: $count"
Log ('=' * 70)

if ($count -eq 0) {
    Log ""
    Log "Geen ontbrekende updates. Server is up-to-date volgens Microsoft Update."
    return
}

# --- Per update: details loggen en download-URL's verzamelen ---
$downloadList = @()

for ($i = 0; $i -lt $count; $i++) {
    $u = $result.Updates.Item($i)
    $kb = ($u.KBArticleIDs | ForEach-Object { "KB$_" }) -join ', '

    Log ""
    Log ("-" * 70)
    Log "[$($i+1)/$count] $($u.Title)"
    Log "  KB:        $kb"
    Log "  Ernst:     $($u.MsrcSeverity)"
    Log "  UpdateID:  $($u.Identity.UpdateID)"

    # Download-URL's uit de bundle halen (bundelt vaak de echte .msu)
    $bundled = $u.BundledUpdates
    if ($bundled.Count -eq 0) {
        # Geen bundle, probeer update zelf
        foreach ($c in $u.DownloadContents) {
            if ($c.DownloadUrl) {
                Log "  URL:       $($c.DownloadUrl)"
                $downloadList += [PSCustomObject]@{ KB = $kb; Url = $c.DownloadUrl }
            }
        }
    } else {
        for ($b = 0; $b -lt $bundled.Count; $b++) {
            $bu = $bundled.Item($b)
            foreach ($c in $bu.DownloadContents) {
                if ($c.DownloadUrl) {
                    Log "  URL:       $($c.DownloadUrl)"
                    $downloadList += [PSCustomObject]@{ KB = $kb; Url = $c.DownloadUrl }
                }
            }
        }
    }
}

# --- Download-URL's apart wegschrijven ---
$urlFile = Join-Path $outDir 'download_urls.txt'
$downloadList | ForEach-Object { $_.Url } | Sort-Object -Unique | Set-Content $urlFile
Log ""
Log ('=' * 70)
Log "Alle download-URL's staan in: $urlFile"

# --- Bestanden downloaden via BITS ---
Log ""
Log "Downloaden naar $outDir ..."
$n = 0
foreach ($item in ($downloadList | Sort-Object Url -Unique)) {
    $n++
    $fileName = Split-Path $item.Url -Leaf
    # Zorg dat de bestandsnaam het KB-nummer bevat voor herkenbaarheid
    $kbClean = ($item.KB -replace '[, ]', '_')
    $dest = Join-Path $outDir "$($kbClean)__$fileName"

    Log "  [$n] $fileName"
    try {
        Start-BitsTransfer -Source $item.Url -Destination $dest -ErrorAction Stop
        $size = [math]::Round((Get-Item $dest).Length / 1MB, 1)
        Log "       OK ($size MB)"
    }
    catch {
        Log "       MISLUKT: $($_.Exception.Message)"
        Log "       Handmatig downloaden via bovenstaande URL."
    }
}

Log ""
Log ('=' * 70)
Log "Klaar: $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss')"
Log "Rapport:   $logFile"
Log "URL-lijst: $urlFile"
Log "Bestanden: $outDir"