restrict editing and creating of sys_categories in TYPO3 to certain category mounts - typo3

Question

i need to restrict the creating and editing of sys_category entries to certain category mounts for user oder usergroups.
More precise: a given backend user should be able to create a new category but not anywhere in the category treee but only under a certain category mount. And he should not be able to delete or edit categories which are not under his category mount.
Please note: i don't mean displaying only branches of category trees in other records like news. I do mean creating and editing sys_category records.
Is there a possibility?
Thanks!

Answer 1

Register 2 new Hooks:
// Check record while creating categories
$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_tcemain.php']['processDatamapClass'][]
= \JWeiland\SitePackage\Hooks\CheckCategoryRecords::class;
// Check record while moving categories
$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_tcemain.php']['processCmdmapClass'][]
= \JWeiland\SitePackage\Hooks\CheckCategoryRecords::class;
Add the file for Hook:
class CheckCategoryRecords
{
public function processDatamap_beforeStart(DataHandler $dataHandler): void
{
$context = GeneralUtility::makeInstance(\TYPO3\CMS\Core\Context\Context::class);
$groups = $context->getPropertyFromAspect('backend.user', 'groupIds');
if (
array_key_exists('sys_category', $dataHandler->datamap)
&& is_array($dataHandler->datamap['sys_category'])
&& !empty($dataHandler->datamap['sys_category'])
&& !$this->getBackendUserAuthentication()->isAdmin()
) {
// Hook is only valid, if a record is saved and editor has no admin rights
foreach ($dataHandler->datamap['sys_category'] as $uid => $categoryRecord) {
if (!isset($categoryRecord['pid'])) {
continue;
}
//...add further conditions, if needed...
if (!in_array($groupUidWithCategoryRights, $groups, true)) {
// Add further condition, if category is allowed for given parent column
// editor is not allowed to add or move categories
unset($dataHandler->datamap['sys_category'][$uid]);
$dataHandler->log(
'sys_category',
$uid,
1,
0,
1,
'You are not allowed to create or move categories'
);
}
}
}
}
}