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

    [Parameter(Mandatory = $true)]
    [string]$ListTitle,

    [Parameter(Mandatory = $true)]
    [string]$ExpiryFieldInternalName,

    [Guid]$FieldCustomizerComponentId = 'a555f4fc-d6a6-4421-8189-457449d9bbde'
)

$isapiPath = Join-Path ([Environment]::GetFolderPath('CommonProgramFiles')) 'microsoft shared\Web Server Extensions\16\ISAPI'
Add-Type -Path (Join-Path $isapiPath 'Microsoft.SharePoint.Client.Runtime.dll')
Add-Type -Path (Join-Path $isapiPath 'Microsoft.SharePoint.Client.dll')

$context = New-Object Microsoft.SharePoint.Client.ClientContext($SiteUrl)
$context.Credentials = [System.Net.CredentialCache]::DefaultNetworkCredentials

try {
    $list = $context.Web.Lists.GetByTitle($ListTitle)
    $field = $list.Fields.GetByInternalNameOrTitle($ExpiryFieldInternalName)
    $context.Load($list)
    $context.Load($field)
    $context.ExecuteQuery()

    if ($field.ClientSideComponentId -ne $FieldCustomizerComponentId) {
        throw "Das Feld '$($field.InternalName)' ist nicht mit dem erwarteten ExpiryIndicator-Field-Customizer verbunden."
    }

    if ($PSCmdlet.ShouldProcess("$($list.Title)/$($field.InternalName)", 'Field-Customizer-Verknüpfung entfernen')) {
        $field.ClientSideComponentId = [Guid]::Empty
        $field.ClientSideComponentProperties = ''
        $field.Update()
        $context.ExecuteQuery()
        Write-Host "ExpiryIndicator-Verknüpfung wurde entfernt. Feld und Daten bleiben unverändert."
    }
}
finally {
    $context.Dispose()
}