<#
.SYNOPSIS
  Herstart relevante services wanneer een VSS back-up is mislukt.

.DESCRIPTION
  - Zoekt in de Event Logs (Application/System) naar recente VSS-fouten.
  - (Optioneel) Controleert VSS-writers via 'vssadmin list writers' op Failed.
  - Herstart een configureerbare set van VSS-gerelateerde services.
  - Logt acties naar bestand en uitvoer; verifieert na afloop de writer-status.

.PARAMETER LookbackMinutes
  Periode (minuten) om terug te kijken voor VSS-fouten in Event Logs.

.PARAMETER RequireFailedWriter
  Alleen services herstarten als er daadwerkelijk één of meer VSS-writers in Failed staan.

.PARAMETER Force
  Stop-Service gebruikt -Force wanneer nodig.

.PARAMETER LogPath
  Pad naar logbestand.

.PARAMETER ServiceList
  Overschrijf de standaardlijst met te herstarten services (servicenamen, niet weergavenamen).

.NOTES
  - Run als Administrator.
  - Pas de standaard ServiceList aan voor de betreffende serverrol(len).
#>

[CmdletBinding()]
param(
    [int]$LookbackMinutes = 60,
    [switch]$RequireFailedWriter,
    [switch]$Force,
    [string]$LogPath = "C:\Windows\Temp\VSS-Restart-$(Get-Date -Format 'yyyyMMdd_HHmmss').log",
    [string[]]$ServiceList = @(
        # Kern VSS
        'VSS',          # Volume Shadow Copy
        'SwPrv',        # Microsoft Software Shadow Copy Provider
        'EventSystem',  # COM+ Event System
        'COMSysApp',    # COM+ System Application (soms niet nodig/aanwezig)

        # Veelvoorkomende writers (pas aan op rol)
        'SQLWriter',    # SQL Server VSS Writer (indien aanwezig)
        'IISADMIN',     # IIS Admin Service (indien aanwezig)
        'W3SVC',        # World Wide Web Publishing (indien aanwezig)
        'BITS',         # Background Intelligent Transfer Service (soms storend bij backups)
        'wbengine',     # Windows Backup Engine (indien gebruikt)

        # Hyper-V (host of guest; alleen herstarten als aanwezig)
        'vmicvss',      # Hyper-V Volume Shadow Copy Requestor (Guest service)
        'vmms'          # Hyper-V Virtual Machine Management (Host)
    )
)

# ---------- Auto-defaults wanneer GEEN parameters zijn meegegeven ----------
$NoParams = ($PSBoundParameters.Count -eq 0)
if ($NoParams) {
    try {
        if (-not (Test-Path -LiteralPath 'C:\Temp')) {
            New-Item -ItemType Directory -Path 'C:\Temp' -Force | Out-Null
        }
    } catch {}
    $LogPath = "C:\Temp\VSS-Restart-$(Get-Date -Format 'yyyyMMdd_HHmmss').log"
}
# Force-effectiviteit wordt later bepaald met $ForceEffective i.p.v. $Force direct te wijzigen
$ForceEffective = ($NoParams -or $Force.IsPresent)

# ---------- Helpers ----------
function Write-Log {
    param([string]$Message)
    $stamp = (Get-Date).ToString('yyyy-MM-dd HH:mm:ss')
    $line  = "[$stamp] $Message"
    Write-Output $line
    try { Add-Content -Path $LogPath -Value $line -Encoding UTF8 -ErrorAction Stop } catch {}
}

function Test-VssErrors {
    param([int]$Minutes)
    $since = (Get-Date).AddMinutes(-$Minutes)

    $filters = @(
        @{ LogName='Application'; ProviderName='VSS' },
        @{ LogName='System';      ProviderName='VolSnap' },                  # Volsnap driver errors
        @{ LogName='Application'; ProviderName='Backup' },                   # Sommige backupapps loggen onder 'Backup'
        @{ LogName='Application'; ProviderName='Windows Server Backup' }     # WSB
    )

    $events = foreach ($f in $filters) {
        try {
            Get-WinEvent -FilterHashtable @{
                LogName      = $f.LogName
                ProviderName = $f.ProviderName
                Level        = 2           # Error
                StartTime    = $since
            } -ErrorAction SilentlyContinue
        } catch {}
    }

    $hasErrors = $false
    if ($events) {
        $hasErrors = $true
        Write-Log "VSS/VOLSNAP/Backup fouten gevonden sinds ${since}:"
        $events | Sort-Object TimeCreated -Descending | Select-Object -First 10 |
            ForEach-Object {
                Write-Log ("  {0:u} {1} {2}: {3}" -f $_.TimeCreated, $_.ProviderName, $_.Id, ($_.Message -replace '\r?\n',' '))
            }
    } else {
        Write-Log "Geen VSS-gerelateerde fouten gevonden sinds $since."
    }
    return $hasErrors
}

function Get-VssWriterStatus {
    # Parse 'vssadmin list writers' op Failed writers
    $failed = @()
    $all    = @()

    $output = & vssadmin list writers 2>$null
    if (-not $output) {
        Write-Log "Kon 'vssadmin list writers' niet uitvoeren of geen output."
        return ,@(),@()
    }

    $current = [ordered]@{ Writer=''; State=''; LastError='' }
    foreach ($line in $output) {
        if ($line -match "^\s*Writer name:\s+'(.+?)'") {
            if ($current.Writer) { $all += [pscustomobject]$current }
            $current = [ordered]@{ Writer=$matches[1]; State=''; LastError='' }
        } elseif ($line -match '^\s*State:\s+\[(\d+)\]\s+(.+)$') {
            $current.State = "$($matches[1]) $($matches[2])"
        } elseif ($line -match '^\s*Last error:\s+(.+)$') {
            $current.LastError = $matches[1]
        }
    }
    if ($current.Writer) { $all += [pscustomobject]$current }

    foreach ($w in $all) {
        if ($w.State -match '^\s*9\b|Failed') {
            $failed += $w
        }
    }
    return ,$failed,$all
}

function Restart-ServiceSafe {
    param(
        [string]$Name,
        [switch]$ForceStop
    )
    try {
        $svc = Get-Service -Name $Name -ErrorAction Stop
    } catch {
        Write-Log "Service '$Name' niet gevonden; overslaan."
        return
    }

    # Sommige services zijn al gestopt of disabled
    if ($svc.Status -eq 'Running') {
        Write-Log "Stoppen service '$Name'..."
        try {
            if ($ForceStop) {
                Stop-Service -Name $Name -Force -ErrorAction Stop
            } else {
                Stop-Service -Name $Name -ErrorAction Stop
            }
            $svc.WaitForStatus('Stopped','00:00:20')
        } catch {
            Write-Log "Kon service '$Name' niet stoppen: $($_.Exception.Message)"
        }
    } else {
        Write-Log "Service '$Name' is niet Running (status=$($svc.Status)); stop stap overslaan."
    }

    Write-Log "Starten service '$Name'..."
    try {
        Start-Service -Name $Name -ErrorAction Stop
        (Get-Service -Name $Name).WaitForStatus('Running','00:00:20')
        Write-Log "Service '$Name' draait."
    } catch {
        Write-Log "Kon service '$Name' niet starten: $($_.Exception.Message)"
    }
}

# ---------- Main ----------
Write-Log "=== VSS Service Restart Script gestart op $(hostname) ==="
Write-Log "Logbestand: $LogPath"

$hasVssErrors = Test-VssErrors -Minutes $LookbackMinutes

$failedWriters = @()
$allWriters    = @()
$failedWriters, $allWriters = Get-VssWriterStatus

if ($failedWriters.Count -gt 0) {
    Write-Log "VSS-writers in FAILED staat:"
    $failedWriters | ForEach-Object { Write-Log ("  {0} | State={1} | LastError={2}" -f $_.Writer, $_.State, $_.LastError) }
} else {
    Write-Log "Geen FAILED VSS-writers gedetecteerd."
}

$shouldAct = $hasVssErrors -or ($failedWriters.Count -gt 0)
if ($RequireFailedWriter -and $failedWriters.Count -eq 0) {
    $shouldAct = $false
    Write-Log "RequireFailedWriter is ingeschakeld en er zijn geen failed writers; geen services herstart."
}

if ($shouldAct) {
    Write-Log "Services worden herstart. Aantal in lijst: $($ServiceList.Count)."
    foreach ($svcName in $ServiceList) {
        Restart-ServiceSafe -Name $svcName -ForceStop:$ForceEffective
    }

    Start-Sleep -Seconds 5
    Write-Log "Hercontrole VSS-writers na herstart..."
    $failedAfter, $allAfter = Get-VssWriterStatus

    if ($failedAfter.Count -eq 0) {
        Write-Log "Alle VSS-writers zijn nu OK."
        exit 0
    } else {
        Write-Log "Nog steeds FAILED VSS-writers na herstart:"
        $failedAfter | ForEach-Object { Write-Log ("  {0} | State={1} | LastError={2}" -f $_.Writer, $_.State, $_.LastError) }
        exit 2
    }
} else {
    Write-Log "Geen actie ondernomen; geen relevante fouten binnen de lookback of policy verhindert actie."
    exit 0
}