param(
    [Parameter(Mandatory = $true)]
    [string]$SiteUrl,

    [string]$PageName = 'PortalSettingsV3',

    [switch]$Publish
)

$ErrorActionPreference = 'Stop'
$componentId = 'c41d05ec-0682-4af0-b807-649806ed56b3'

if (-not (Get-Command Connect-PnPOnline -ErrorAction SilentlyContinue)) {
    throw 'PnP PowerShell wurde nicht gefunden. Bitte das zur SharePoint-SE-Umgebung passende PnP-Modul laden.'
}

Connect-PnPOnline -Url $SiteUrl -CurrentCredentials

$pageFileName = if ($PageName.EndsWith('.aspx', [StringComparison]::OrdinalIgnoreCase)) { $PageName } else { $PageName + '.aspx' }
$pageIdentity = $pageFileName.Substring(0, $pageFileName.Length - 5)
$page = Get-PnPClientSidePage -Identity $pageFileName -ErrorAction SilentlyContinue

if (-not $page) {
    Write-Host "Erstelle moderne Seite $pageFileName ..." -ForegroundColor Yellow
    $page = Add-PnPClientSidePage -Name $pageIdentity -LayoutType Article
}
else {
    Write-Host "Verwende vorhandene moderne Seite $pageFileName." -ForegroundColor Yellow
}

$existingControl = @($page.Controls | Where-Object {
    $_.WebPartId -and $_.WebPartId.ToString().Equals($componentId, [StringComparison]::OrdinalIgnoreCase)
}) | Select-Object -First 1

if (-not $existingControl) {
    if (-not $page.Sections -or $page.Sections.Count -eq 0) {
        Add-PnPClientSidePageSection -Page $page -SectionTemplate OneColumn -Order 1 | Out-Null
    }
    $component = Get-PnPAvailableClientSideComponents -Page $page | Where-Object {
        $_.Id.ToString().Equals($componentId, [StringComparison]::OrdinalIgnoreCase)
    } | Select-Object -First 1
    if (-not $component) {
        throw 'Das Portal Settings V3 WebPart ist nicht verfügbar. Ist die App im Root Web installiert beziehungsweise aktualisiert?'
    }
    Add-PnPClientSideWebPart -Page $page -Component $component -Section 1 -Column 1 -Order 1 | Out-Null
    Write-Host 'Portal Settings WebPart wurde hinzugefügt.' -ForegroundColor Green
}
else {
    Write-Host 'Portal Settings WebPart ist bereits vorhanden.' -ForegroundColor Green
}

$page.Save()
if ($Publish) { $page.Publish() }

Write-Host ("Fertig: " + $SiteUrl.TrimEnd('/') + '/SitePages/' + $pageFileName) -ForegroundColor Green