Set USERDEF1 (or USERDEF2) in a language menu on record detail pages if the record is not translated. #TYPO3

MenuUtility.php

<?php
namespace BGM\BgmTheme\Utility;

/*
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */

use TYPO3\CMS\Core\Utility\GeneralUtility;

/**
 * Class MenuUtility
 */
class MenuUtility {

    /**
     * Check if we are on the detail view of a record and if the record is translated.
     * If the record is not translated, the ITEM_STATE of the language menu item is set to USERDEF1 or USERDEF2
     * as it is also done for pages (see AbstractMenuContentObject::prepareMenuItemsForLanguageMenu() "Checking if the
     * "disabled" state should be set.").
     *
     * TypoScript configuration example for EXT:news
     *
     * lib.languageSelector = HMENU
     * lib.languageSelector {
     *   special = language
     *   [...]
     *   1 = TMENU
     *   1 {
     *     [...]
     *     itemArrayProcFunc = BGM\BgmTheme\Utility\MenuUtility->checkForRecordTranslations
     *     itemArrayProcFunc.getParameters {
     *       # GET.PARAMETER.WITH.RECORD.UID = TABLENAME
     *       tx_news_pi1.news = tx_news_domain_model_news
     *     }
     *   }
     * }
     *
     * @see \TYPO3\CMS\Frontend\ContentObject\Menu\AbstractMenuContentObject::prepareMenuItemsForLanguageMenu()
     * @param array $menuArr
     * @param array $conf
     * @return array $menuArr
     */
    public function checkForRecordTranslations($menuArr, $conf){
        $check = $this->shouldCheck($conf['getParameters.'], GeneralUtility::_GET());
        if($check !== false){
            /** @var \TYPO3\CMS\Frontend\ContentObject\Menu\TextMenuContentObject $parentObject */
            $parentObject = $conf['parentObj'];
            /** @var \TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController $tsfe */
            $tsfe = $this->getTypoScriptFrontendController();
            /** @var \TYPO3\CMS\Core\Database\DatabaseConnection $db */
            $db = $this->getDatabaseConnection();
            foreach($menuArr as &$menuItem){
                /** @var int $sUid current menu item language id */
                $sUid = intval($menuItem['_PAGES_OVERLAY_LANGUAGE']);
                // Find overlay record:
                if ($sUid) {
                    $currentRecord = $db->exec_SELECTgetSingleRow(
                        '*',
                        $db->quoteStr($check['table'], $check['table']),
                        'uid = ' . intval($check['recordUid'])
                    );
                    $overlayMode = $GLOBALS['TSFE']->sys_language_mode === 'strict' ? 'hideNonTranslated' : '';
                    $lRecs = $parentObject->sys_page->getRecordOverlay($check['table'], $currentRecord, $sUid, $overlayMode);
                } else {
                    $lRecs = [];
                }
                // Checking if the "disabled" state should be set.
                if (GeneralUtility::hideIfNotTranslated($tsfe->page['l18n_cfg']) && $sUid &&
                    empty($lRecs) || GeneralUtility::hideIfDefaultLanguage($tsfe->page['l18n_cfg']) &&
                    (!$sUid || empty($lRecs)) ||
                    !$parentObject->conf['special.']['normalWhenNoLanguage'] && $sUid && empty($lRecs)
                ) {
                    $menuItem['ITEM_STATE'] = $tsfe->sys_language_uid == $sUid ? 'USERDEF2' : 'USERDEF1';
                }
            }
        }
        return $menuArr;
    }

    /**
     * Walk through GET-Parameters and TypoScript-Configuration to check if we should do something.
     * If we should do something this function returns the tablename and uid of the record to check.
     * Else it returns false.
     *
     * @param array $parameter
     * @return mixed
     */
    protected function shouldCheck($configuration, $getParameters){
        $result = false;
        foreach($configuration as $key => $configuratedParameter) {
            $getParameterKey = $key;
            if(is_array($configuratedParameter)){
                $getParameterKey = rtrim($key, '.');
            }
            if (isset($getParameters[$getParameterKey])){
                if(is_array($getParameters[$getParameterKey]) && is_array($configuratedParameter)){
                    $result = $this->shouldCheck($configuratedParameter, $getParameters[$getParameterKey]);
                } elseif (is_string($configuratedParameter) && $configuratedParameter !== 0 && isset($getParameters[$getParameterKey])){
                    $result = [
                        'table' => $configuratedParameter,
                        'recordUid' => $getParameters[$getParameterKey],
                    ];
                }
            }
        }
        return $result;
    }

    /**
     * @return \TYPO3\CMS\Core\Database\DatabaseConnection
     */
    protected function getDatabaseConnection()
    {
        return $GLOBALS['TYPO3_DB'];
    }

    /**
     * @return \TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController
     */
    protected function getTypoScriptFrontendController()
    {
        return $GLOBALS['TSFE'];
    }
}

Thanks for the work, this saved me some hours. I forked it to work with TYPO3 9 https://gist.github.com/rbqueo/1a6e4d0e80df4a371ea39a287b57650f