<?php
namespace Kitodo\Dlf\Common;

/**
 * (c) Kitodo. Key to digital objects e.V. <contact@kitodo.org>
 *
 * This file is part of the Kitodo and TYPO3 projects.
 *
 * @license GNU General Public License version 3 or later.
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 */

/**
 * Helper class for the 'dlf' extension
 *
 * @author Sebastian Meyer <sebastian.meyer@slub-dresden.de>
 * @author Henrik Lochmann <dev@mentalmotive.com>
 * @package TYPO3
 * @subpackage dlf
 * @access public
 */
class Helper {
    /**
     * The extension key
     *
     * @var string
     * @access public
     */
    public static $extKey = 'dlf';

    /**
     * The locallang array for flash messages
     *
     * @var array
     * @access protected
     */
    protected static $messages = [];

    /**
     * Adds a message to the message queue.
     *
     * @access public
     *
     * @param \TYPO3\CMS\Core\Messaging\FlashMessage $message: Instance of \TYPO3\CMS\Core\Messaging\FlashMessage
     *
     * @return void
     */
    public static function addMessage(\TYPO3\CMS\Core\Messaging\FlashMessage $message) {
        $flashMessageService = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\Messaging\FlashMessageService::class);
        $flashMessageService->getMessageQueueByIdentifier()->enqueue($message);
    }

    /**
     * Check if given identifier is a valid identifier of the German National Library
     * @see http://support.d-nb.de/iltis/onlineRoutinen/Pruefziffernberechnung.htm
     *
     * @access public
     *
     * @param string $id: The identifier to check
     * @param string $type: What type is the identifier supposed to be?
     *                      Possible values: PPN, IDN, PND, ZDB, SWD, GKD
     *
     * @return boolean Is $id a valid GNL identifier of the given $type?
     */
    public static function checkIdentifier($id, $type) {
        $digits = substr($id, 0, 8);
        $checksum = 0;
        for ($i = 0, $j = strlen($digits); $i < $j; $i++) {
            $checksum += (9 - $i) * intval(substr($digits, $i, 1));
        }
        $checksum = (11 - ($checksum % 11)) % 11;
        switch (strtoupper($type)) {
            case 'PPN':
            case 'IDN':
            case 'PND':
                if ($checksum == 10) {
                    $checksum = 'X';
                }
                if (!preg_match('/[0-9]{8}[0-9X]{1}/i', $id)) {
                    return FALSE;
                } elseif (strtoupper(substr($id, -1, 1)) != $checksum) {
                    return FALSE;
                }
                break;
            case 'ZDB':
                if ($checksum == 10) {
                    $checksum = 'X';
                }
                if (!preg_match('/[0-9]{8}-[0-9X]{1}/i', $id)) {
                    return FALSE;
                } elseif (strtoupper(substr($id, -1, 1)) != $checksum) {
                    return FALSE;
                }
                break;
            case 'SWD':
                $checksum = 11 - $checksum;
                if (!preg_match('/[0-9]{8}-[0-9]{1}/i', $id)) {
                    return FALSE;
                } elseif ($checksum == 10) {
                    return self::checkIdentifier(($digits + 1).substr($id, -2, 2), 'SWD');
                } elseif (substr($id, -1, 1) != $checksum) {
                    return FALSE;
                }
                break;
            case 'GKD':
                $checksum = 11 - $checksum;
                if ($checksum == 10) {
                    $checksum = 'X';
                }
                if (!preg_match('/[0-9]{8}-[0-9X]{1}/i', $id)) {
                    return FALSE;
                } elseif (strtoupper(substr($id, -1, 1)) != $checksum) {
                    return FALSE;
                }
                break;
        }
        return TRUE;
    }

    /**
     * Decrypt encrypted value with given control hash
     * @see http://yavkata.co.uk/weblog/php/securing-html-hidden-input-fields-using-encryption-and-hashing/
     *
     * @access public
     *
     * @param string $encrypted: The encrypted value to decrypt
     * @param string $hash: The control hash for decrypting
     *
     * @return mixed The decrypted value or NULL on error
     */
    public static function decrypt($encrypted, $hash) {
        $decrypted = NULL;
        if (empty($encrypted)
            || empty($hash)) {
            self::devLog('Invalid parameters given for decryption', DEVLOG_SEVERITY_ERROR);
            return;
        }
        if (empty($GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'])) {
            self::devLog('No encryption key set in TYPO3 configuration', DEVLOG_SEVERITY_ERROR);
            return;
        }
        $iv = substr(md5($GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey']), 0, openssl_cipher_iv_length('BF-CFB'));
        $decrypted = openssl_decrypt($encrypted, 'BF-CFB', substr($GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'], 0, 56), 0, $iv);
        $salt = substr($hash, 0, 10);
        $hashed = $salt.substr(sha1($salt.$decrypted), -10);
        if ($hashed !== $hash) {
            self::devLog('Invalid hash "'.$hash.'" given for decryption', DEVLOG_SEVERITY_WARNING);
            return;
        }
        return $decrypted;
    }

    /**
     * Add a message to the TYPO3 developer log
     *
     * @access public
     *
     * @param string $message: The message to log
     * @param integer $severity: The severity of the message
     *                           0 is info, 1 is notice, 2 is warning, 3 is fatal error, -1 is "OK" message
     *
     * @return void
     */
    public static function devLog($message, $severity = 0) {
        if (TYPO3_DLOG) {
            $stacktrace = debug_backtrace(0, 2);
            // Set some defaults.
            $caller = 'Kitodo\Dlf\Default\UnknownClass::unknownMethod';
            $args = [];
            $data = [];
            if (!empty($stacktrace[1])) {
                $caller = $stacktrace[1]['class'].$stacktrace[1]['type'].$stacktrace[1]['function'];
                foreach ($stacktrace[1]['args'] as $arg) {
                    if (is_bool($arg)) {
                        $args[] = ($arg ? 'TRUE' : 'FALSE');
                    } elseif (is_scalar($arg)) {
                        $args[] = (string) $arg;
                    } elseif (is_null($arg)) {
                        $args[] = 'NULL';
                    } elseif (is_array($arg)) {
                        $args[] = '[data]';
                        $data[] = $arg;
                    } elseif (is_object($arg)) {
                        $args[] = '['.get_class($arg).']';
                        $data[] = $arg;
                    }
                }
            }
            $arguments = '('.implode(', ', $args).')';
            $additionalData = (empty($data) ? FALSE : $data);
            \TYPO3\CMS\Core\Utility\GeneralUtility::devLog('['.$caller.$arguments.'] '.$message, self::$extKey, $severity, $additionalData);
        }
    }

    /**
     * Encrypt the given string
     *
     * @access public
     *
     * @param string $string: The string to encrypt
     *
     * @return array Array with encrypted string and control hash
     */
    public static function encrypt($string) {
        if (empty($GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'])) {
            self::devLog('No encryption key set in TYPO3 configuration', DEVLOG_SEVERITY_ERROR);
            return;
        }
        $iv = substr(md5($GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey']), 0, openssl_cipher_iv_length('BF-CFB'));
        $encrypted = openssl_encrypt($string, 'BF-CFB', substr($GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'], 0, 56), 0, $iv);
        $salt = substr(md5(uniqid(rand(), TRUE)), 0, 10);
        $hash = $salt.substr(sha1($salt.$string), -10);
        return ['encrypted' => $encrypted, 'hash' => $hash];
    }

    /**
     * Get a backend user object (even in frontend mode)
     *
     * @access public
     *
     * @return \TYPO3\CMS\Core\Authentication\BackendUserAuthentication Instance of \TYPO3\CMS\Core\Authentication\BackendUserAuthentication or NULL on failure
     */
    public static function getBeUser() {
        if (TYPO3_MODE === 'FE'
            || TYPO3_MODE === 'BE') {
            // Initialize backend session with CLI user's rights.
            $userObj = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\Authentication\BackendUserAuthentication::class);
            $userObj->dontSetCookie = TRUE;
            $userObj->start();
            $userObj->setBeUserByName('_cli_dlf');
            $userObj->backendCheckLogin();
            return $userObj;
        } else {
            self::devLog('Unexpected TYPO3_MODE "'.TYPO3_MODE.'"', DEVLOG_SEVERITY_ERROR);
            return;
        }
    }

    /**
     * Clean up a string to use in an URL.
     *
     * @access public
     *
     * @param string $string: The string to clean up
     *
     * @return string The cleaned up string
     */
    public static function getCleanString($string) {
        // Convert to lowercase.
        $string = strtolower($string);
        // Remove non-alphanumeric characters.
        $string = preg_replace('/[^a-z0-9_\s-]/', '', $string);
        // Remove multiple dashes or whitespaces.
        $string = preg_replace('/[\s-]+/', ' ', $string);
        // Convert whitespaces and underscore to dash.
        $string = preg_replace('/[\s_]/', '-', $string);
        return $string;
    }

    /**
     * Get the current frontend user object
     *
     * @access public
     *
     * @return \TYPO3\CMS\Frontend\Authentication\FrontendUserAuthentication Instance of \TYPO3\CMS\Frontend\Authentication\FrontendUserAuthentication or NULL on failure
     */
    public static function getFeUser() {
        if (TYPO3_MODE === 'FE') {
            // Check if a user is currently logged in.
            if (!empty($GLOBALS['TSFE']->loginUser)) {
                return $GLOBALS['TSFE']->fe_user;
            } elseif (\TYPO3\CMS\Core\Utility\GeneralUtility::_GP('eID') !== NULL) {
                return \TYPO3\CMS\Frontend\Utility\EidUtility::initFeUser();
            }
        } else {
            self::devLog('Unexpected TYPO3_MODE "'.TYPO3_MODE.'"', DEVLOG_SEVERITY_ERROR);
        }
        return;
    }

    /**
     * Get the registered hook objects for a class
     *
     * @access public
     *
     * @param string $scriptRelPath: The path to the class file
     *
     * @return array Array of hook objects for the class
     */
    public static function getHookObjects($scriptRelPath) {
        $hookObjects = [];
        if (is_array($GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS'][self::$extKey.'/'.$scriptRelPath]['hookClass'])) {
            foreach ($GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS'][self::$extKey.'/'.$scriptRelPath]['hookClass'] as $classRef) {
                $hookObjects[] = &\TYPO3\CMS\Core\Utility\GeneralUtility::getUserObj($classRef);
            }
        }
        return $hookObjects;
    }

    /**
     * Get the "index_name" for an UID
     *
     * @access public
     *
     * @param integer $uid: The UID of the record
     * @param string $table: Get the "index_name" from this table
     * @param integer $pid: Get the "index_name" from this page
     *
     * @return string "index_name" for the given UID
     */
    public static function getIndexName($uid, $table, $pid = -1) {
        // Save parameters for logging purposes.
        $_uid = $uid;
        $_pid = $pid;
        // Sanitize input.
        $uid = max(intval($uid), 0);
        if (!$uid
            || !in_array($table, ['tx_dlf_collections', 'tx_dlf_libraries', 'tx_dlf_metadata', 'tx_dlf_structures', 'tx_dlf_solrcores'])) {
            self::devLog('Invalid UID "'.$uid.'" or table "'.$table.'"', DEVLOG_SEVERITY_ERROR);
            return '';
        }
        $where = '';
        // Should we check for a specific PID, too?
        if ($pid !== -1) {
            $pid = max(intval($pid), 0);
            $where = ' AND '.$table.'.pid='.$pid;
        }
        // Get index_name from database.
        $result = $GLOBALS['TYPO3_DB']->exec_SELECTquery(
            $table.'.index_name AS index_name',
            $table,
            $table.'.uid='.$uid
                .$where
                .self::whereClause($table),
            '',
            '',
            '1'
        );
        if ($GLOBALS['TYPO3_DB']->sql_num_rows($result) > 0) {
            $resArray = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($result);
            return $resArray['index_name'];
        } else {
            self::devLog('No "index_name" with UID '.$uid.' and PID '.$pid.' found in table "'.$table.'"', DEVLOG_SEVERITY_WARNING);
            return '';
        }
    }

    /**
     * Get the UID for a given "index_name"
     *
     * @access public
     *
     * @param integer $index_name: The index_name of the record
     * @param string $table: Get the "index_name" from this table
     * @param integer $pid: Get the "index_name" from this page
     *
     * @return string "uid" for the given index_name
     */
    public static function getIdFromIndexName($index_name, $table, $pid = -1) {
        // Save parameters for logging purposes.
        $_index_name = $index_name;
        $_pid = $pid;
        if (!$index_name
            || !in_array($table, ['tx_dlf_collections', 'tx_dlf_libraries', 'tx_dlf_metadata', 'tx_dlf_structures', 'tx_dlf_solrcores'])) {
            self::devLog('Invalid UID '.$index_name.' or table "'.$table.'"', DEVLOG_SEVERITY_ERROR);
            return '';
        }
        $where = '';
        // Should we check for a specific PID, too?
        if ($pid !== -1) {
            $pid = max(intval($pid), 0);
            $where = ' AND '.$table.'.pid='.$pid;
        }
        // Get index_name from database.
        $result = $GLOBALS['TYPO3_DB']->exec_SELECTquery(
            $table.'.uid AS uid',
            $table,
            $table.'.index_name="'.$index_name.'"'
                .$where
                .self::whereClause($table),
            '',
            '',
            '1'
        );
        if ($GLOBALS['TYPO3_DB']->sql_num_rows($result) > 0) {
            $resArray = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($result);
            return $resArray['uid'];
        } else {
            self::devLog('No UID for given index_name "'.$index_name.'" and PID '.$pid.' found in table "'.$table.'"', DEVLOG_SEVERITY_WARNING);
            return '';
        }
    }

    /**
     * Get language name from ISO code
     *
     * @access public
     *
     * @param string $code: ISO 639-1 or ISO 639-2/B language code
     *
     * @return string Localized full name of language or unchanged input
     */
    public static function getLanguageName($code) {
        // Analyze code and set appropriate ISO table.
        $isoCode = strtolower(trim($code));
        if (preg_match('/^[a-z]{3}$/', $isoCode)) {
            $file = \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::extPath(self::$extKey).'Resources/Private/ISO-639/iso-639-2b.xml';
        } elseif (preg_match('/^[a-z]{2}$/', $isoCode)) {
            $file = \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::extPath(self::$extKey).'Resources/Private/ISO-639/iso-639-1.xml';
        } else {
            // No ISO code, return unchanged.
            return $code;
        }
        // Load ISO table and get localized full name of language.
        if (TYPO3_MODE === 'FE') {
            $iso639 = $GLOBALS['TSFE']->readLLfile($file);
            if (!empty($iso639['default'][$isoCode])) {
                $lang = $GLOBALS['TSFE']->getLLL($isoCode, $iso639);
            }
        } elseif (TYPO3_MODE === 'BE') {
            $iso639 = $GLOBALS['LANG']->includeLLFile($file, FALSE, TRUE);
            if (!empty($iso639['default'][$isoCode])) {
                $lang = $GLOBALS['LANG']->getLLL($isoCode, $iso639, FALSE);
            }
        } else {
            self::devLog('Unexpected TYPO3_MODE "'.TYPO3_MODE.'"', DEVLOG_SEVERITY_ERROR);
            return $code;
        }
        if (!empty($lang)) {
            return $lang;
        } else {
            self::devLog('Language code "'.$code.'" not found in ISO-639 table', DEVLOG_SEVERITY_NOTICE);
            return $code;
        }
    }

    /**
     * Wrapper function for getting localized messages in frontend and backend
     *
     * @access public
     *
     * @param string $key: The locallang key to translate
     * @param boolean $hsc: Should the result be htmlspecialchar()'ed?
     * @param string $default: Default return value if no translation is available
     *
     * @return string The translated string or the given key on failure
     */
    public static function getMessage($key, $hsc = FALSE, $default = '') {
        // Set initial output to default value.
        $translated = (string) $default;
        // Load common messages file.
        if (empty(self::$messages)) {
            $file = \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::extPath(self::$extKey, 'Resources/Private/Language/FlashMessages.xml');
            if (TYPO3_MODE === 'FE') {
                self::$messages = $GLOBALS['TSFE']->readLLfile($file);
            } elseif (TYPO3_MODE === 'BE') {
                self::$messages = $GLOBALS['LANG']->includeLLFile($file, FALSE, TRUE);
            } else {
                self::devLog('Unexpected TYPO3_MODE "'.TYPO3_MODE.'"', DEVLOG_SEVERITY_ERROR);
            }
        }
        // Get translation.
        if (!empty(self::$messages['default'][$key])) {
            if (TYPO3_MODE === 'FE') {
                $translated = $GLOBALS['TSFE']->getLLL($key, self::$messages);
            } elseif (TYPO3_MODE === 'BE') {
                $translated = $GLOBALS['LANG']->getLLL($key, self::$messages, FALSE);
            } else {
                self::devLog('Unexpected TYPO3_MODE "'.TYPO3_MODE.'"', DEVLOG_SEVERITY_ERROR);
            }
        }
        // Escape HTML characters if applicable.
        if ($hsc) {
            $translated = htmlspecialchars($translated);
        }
        return $translated;
    }

    /**
     * Get the URN of an object
     * @see http://www.persistent-identifier.de/?link=316
     *
     * @access public
     *
     * @param string $base: The namespace and base URN
     * @param string $id: The object's identifier
     *
     * @return string Uniform Resource Name as string
     */
    public static function getURN($base, $id) {
        $concordance = [
            '0' => 1,
            '1' => 2,
            '2' => 3,
            '3' => 4,
            '4' => 5,
            '5' => 6,
            '6' => 7,
            '7' => 8,
            '8' => 9,
            '9' => 41,
            'a' => 18,
            'b' => 14,
            'c' => 19,
            'd' => 15,
            'e' => 16,
            'f' => 21,
            'g' => 22,
            'h' => 23,
            'i' => 24,
            'j' => 25,
            'k' => 42,
            'l' => 26,
            'm' => 27,
            'n' => 13,
            'o' => 28,
            'p' => 29,
            'q' => 31,
            'r' => 12,
            's' => 32,
            't' => 33,
            'u' => 11,
            'v' => 34,
            'w' => 35,
            'x' => 36,
            'y' => 37,
            'z' => 38,
            '-' => 39,
            ':' => 17,
        ];
        $urn = strtolower($base.$id);
        if (preg_match('/[^a-z0-9:-]/', $urn)) {
            self::devLog('Invalid chars in given parameters', DEVLOG_SEVERITY_WARNING);
            return '';
        }
        $digits = '';
        for ($i = 0, $j = strlen($urn); $i < $j; $i++) {
            $digits .= $concordance[substr($urn, $i, 1)];
        }
        $checksum = 0;
        for ($i = 0, $j = strlen($digits); $i < $j; $i++) {
            $checksum += ($i + 1) * intval(substr($digits, $i, 1));
        }
        $checksum = substr(intval($checksum / intval(substr($digits, -1, 1))), -1, 1);
        return $base.$id.$checksum;
    }

    /**
     * Check if given ID is a valid Pica Production Number (PPN)
     *
     * @access public
     *
     * @param string $id: The identifier to check
     *
     * @return boolean Is $id a valid PPN?
     */
    public static function isPPN($id) {
        return self::checkIdentifier($id, 'PPN');
    }

    /**
     * Load value from user's session.
     *
     * @access public
     *
     * @param string $key: Session data key for retrieval
     *
     * @return mixed Session value for given key or NULL on failure
     */
    public static function loadFromSession($key) {
        // Save parameter for logging purposes.
        $_key = $key;
        // Cast to string for security reasons.
        $key = (string) $key;
        if (!$key) {
            self::devLog('Invalid key "'.$key.'" for session data retrieval', DEVLOG_SEVERITY_WARNING);
            return;
        }
        // Get the session data.
        if (TYPO3_MODE === 'FE') {
            return $GLOBALS['TSFE']->fe_user->getKey('ses', $key);
        } elseif (TYPO3_MODE === 'BE') {
            return $GLOBALS['BE_USER']->getSessionData($key);
        } else {
            self::devLog('Unexpected TYPO3_MODE "'.TYPO3_MODE.'"', DEVLOG_SEVERITY_ERROR);
            return;
        }
    }

    /**
     * Process a data and/or command map with TYPO3 core engine.
     *
     * @access public
     *
     * @param array $data: Data map
     * @param array $cmd: Command map
     * @param boolean $reverseOrder: Should the command map be processed first?
     * @param boolean $be_user: Use current backend user's rights for processing?
     *
     * @return array Array of substituted "NEW..." identifiers and their actual UIDs.
     */
    public static function processDB(array $data = [], array $cmd = [], $reverseOrder = FALSE, $be_user = FALSE) {
        // Instantiate TYPO3 core engine.
        $tce = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\DataHandling\DataHandler::class);
        // Set some configuration variables.
        $tce->stripslashes_values = FALSE;
        // Get backend user for processing.
        if ($be_user
            && isset($GLOBALS['BE_USER'])) {
            $user = $GLOBALS['BE_USER'];
        } else {
            $user = self::getBeUser();
        }
        // Load data and command arrays.
        $tce->start($data, $cmd, $user);
        // Process command map first if default order is reversed.
        if ($cmd
            && $reverseOrder) {
            $tce->process_cmdmap();
        }
        // Process data map.
        if ($data) {
            $tce->process_datamap();
        }
        // Process command map if processing order is not reversed.
        if ($cmd
            && !$reverseOrder) {
            $tce->process_cmdmap();
        }
        return $tce->substNEWwithIDs;
    }

    /**
     * Process a data and/or command map with TYPO3 core engine as admin.
     *
     * @access public
     *
     * @param array $data: Data map
     * @param array $cmd: Command map
     * @param boolean $reverseOrder: Should the command map be processed first?
     *
     * @return array Array of substituted "NEW..." identifiers and their actual UIDs.
     */
    public static function processDBasAdmin(array $data = [], array $cmd = [], $reverseOrder = FALSE) {
        if (TYPO3_MODE === 'BE'
            && $GLOBALS['BE_USER']->isAdmin()) {
            return self::processDB($data, $cmd, $reverseOrder, TRUE);
        } else {
            self::devLog('Current backend user has no admin privileges', DEVLOG_SEVERITY_ERROR);
            return [];
        }
    }

    /**
     * Fetches and renders all available flash messages from the queue.
     *
     * @access public
     *
     * @return string All flash messages in the queue rendered as HTML.
     */
    public static function renderFlashMessages() {
        $flashMessageService = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\Messaging\FlashMessageService::class);
        $content = '';
        // Since TYPO3 7.4.0, \TYPO3\CMS\Core\Messaging\FlashMessageQueue::renderFlashMessages
        // uses htmlspecialchars on all texts, but we have message text with HTML tags.
        // Therefore we copy the implementation from 7.4.0, but remove the htmlspecialchars call.
        $flashMessages = $flashMessageService->getMessageQueueByIdentifier()->getAllMessagesAndFlush();
        if (!empty($flashMessages)) {
            $content .= '<ul class="typo3-messages">';
            foreach ($flashMessages as $flashMessage) {
                $severityClass = sprintf('alert %s', $flashMessage->getClass());
                //~ $messageContent = htmlspecialchars($flashMessage->getMessage());
                $messageContent = $flashMessage->getMessage();
                if ($flashMessage->getTitle() !== '') {
                    $messageContent = sprintf('<h4>%s</h4>', htmlspecialchars($flashMessage->getTitle())).$messageContent;
                }
                $content .= sprintf('<li class="%s">%s</li>', htmlspecialchars($severityClass), $messageContent);
            }
            $content .= '</ul>';
        }
        return $content;
    }

    /**
     * Save given value to user's session.
     *
     * @access public
     *
     * @param mixed $value: Value to save
     * @param string $key: Session data key for saving
     *
     * @return boolean TRUE on success, FALSE on failure
     */
    public static function saveToSession($value, $key) {
        // Save parameter for logging purposes.
        $_key = $key;
        // Cast to string for security reasons.
        $key = (string) $key;
        if (!$key) {
            self::devLog('Invalid key "'.$key.'" for session data saving', DEVLOG_SEVERITY_WARNING);
            return FALSE;
        }
        // Save value in session data.
        if (TYPO3_MODE === 'FE') {
            $GLOBALS['TSFE']->fe_user->setKey('ses', $key, $value);
            $GLOBALS['TSFE']->fe_user->storeSessionData();
            return TRUE;
        } elseif (TYPO3_MODE === 'BE') {
            $GLOBALS['BE_USER']->setAndSaveSessionData($key, $value);
            return TRUE;
        } else {
            self::devLog('Unexpected TYPO3_MODE "'.TYPO3_MODE.'"', DEVLOG_SEVERITY_ERROR);
            return FALSE;
        }
    }

    /**
     * This translates an internal "index_name"
     *
     * @access public
     *
     * @param string $index_name: The internal "index_name" to translate
     * @param string $table: Get the translation from this table
     * @param string $pid: Get the translation from this page
     *
     * @return string Localized label for $index_name
     */
    public static function translate($index_name, $table, $pid) {
        // Save parameters for logging purposes.
        $_index_name = $index_name;
        $_pid = $pid;
        // Load labels into static variable for future use.
        static $labels = [];
        // Sanitize input.
        $pid = max(intval($pid), 0);
        if (!$pid) {
            self::devLog('Invalid PID '.$pid.' for translation', DEVLOG_SEVERITY_WARNING);
            return $index_name;
        }
        // Check if "index_name" is an UID.
        if (\TYPO3\CMS\Core\Utility\MathUtility::canBeInterpretedAsInteger($index_name)) {
            $index_name = self::getIndexName($index_name, $table, $pid);
        }
        /* $labels already contains the translated content element, but with the index_name of the translated content element itself
         * and not with the $index_name of the original that we receive here. So we have to determine the index_name of the
         * associated translated content element. E.g. $labels['title0'] != $index_name = title. */
        // First fetch the uid of the received index_name
        $result = $GLOBALS['TYPO3_DB']->exec_SELECTquery(
            'uid, l18n_parent',
            $table,
            'pid='.$pid
                .' AND index_name="'.$index_name.'"'
                .self::whereClause($table, TRUE),
            '',
            '',
            ''
        );
        if ($GLOBALS['TYPO3_DB']->sql_num_rows($result) > 0) {
            // Now we use the uid of the l18_parent to fetch the index_name of the translated content element.
            $resArray = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($result);
            $result = $GLOBALS['TYPO3_DB']->exec_SELECTquery(
                'index_name',
                $table,
                'pid='.$pid
                    .' AND uid='.$resArray['l18n_parent']
                    .' AND sys_language_uid='.intval($GLOBALS['TSFE']->sys_language_content)
                    .self::whereClause($table, TRUE),
                '',
                '',
                ''
            );
            if ($GLOBALS['TYPO3_DB']->sql_num_rows($result) > 0) {
                // If there is an translated content element, overwrite the received $index_name.
                $resArray = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($result);
                $index_name = $resArray['index_name'];
            }
        }
        // Check if we already got a translation.
        if (empty($labels[$table][$pid][$GLOBALS['TSFE']->sys_language_content][$index_name])) {
            // Check if this table is allowed for translation.
            if (in_array($table, ['tx_dlf_collections', 'tx_dlf_libraries', 'tx_dlf_metadata', 'tx_dlf_structures'])) {
                $additionalWhere = ' AND sys_language_uid IN (-1,0)';
                if ($GLOBALS['TSFE']->sys_language_content > 0) {
                    $additionalWhere = ' AND (sys_language_uid IN (-1,0) OR (sys_language_uid='.intval($GLOBALS['TSFE']->sys_language_content).' AND l18n_parent=0))';
                }
                // Get labels from database.
                $result = $GLOBALS['TYPO3_DB']->exec_SELECTquery(
                    '*',
                    $table,
                    'pid='.$pid
                        .$additionalWhere
                        .self::whereClause($table, TRUE),
                    '',
                    '',
                    ''
                );
                if ($GLOBALS['TYPO3_DB']->sql_num_rows($result) > 0) {
                    while ($resArray = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($result)) {
                        // Overlay localized labels if available.
                        if ($GLOBALS['TSFE']->sys_language_content > 0) {
                            $resArray = $GLOBALS['TSFE']->sys_page->getRecordOverlay($table, $resArray, $GLOBALS['TSFE']->sys_language_content, $GLOBALS['TSFE']->sys_language_contentOL);
                        }
                        if ($resArray) {
                            $labels[$table][$pid][$GLOBALS['TSFE']->sys_language_content][$resArray['index_name']] = $resArray['label'];
                        }
                    }
                } else {
                    self::devLog('No translation with PID '.$pid.' available in table "'.$table.'" or translation not accessible', DEVLOG_SEVERITY_NOTICE);
                }
            } else {
                self::devLog('No translations available for table "'.$table.'"', DEVLOG_SEVERITY_WARNING);
            }
        }
        if (!empty($labels[$table][$pid][$GLOBALS['TSFE']->sys_language_content][$index_name])) {
            return $labels[$table][$pid][$GLOBALS['TSFE']->sys_language_content][$index_name];
        } else {
            return $index_name;
        }
    }

    /**
     * This returns the additional WHERE clause of a table based on its TCA configuration
     *
     * @access public
     *
     * @param string $table: Table name as defined in TCA
     * @param boolean $showHidden: Ignore the hidden flag?
     *
     * @return string Additional WHERE clause
     */
    public static function whereClause($table, $showHidden = FALSE) {
        if (TYPO3_MODE === 'FE') {
            // Table "tx_dlf_formats" always has PID 0.
            if ($table == 'tx_dlf_formats') {
                return \TYPO3\CMS\Backend\Utility\BackendUtility::deleteClause($table);
            }
            // Should we ignore the record's hidden flag?
            $ignoreHide = -1;
            if ($showHidden) {
                $ignoreHide = 1;
            }
            // $GLOBALS['TSFE']->sys_page is not always available in frontend.
            if (is_object($GLOBALS['TSFE']->sys_page)) {
                return $GLOBALS['TSFE']->sys_page->enableFields($table, $ignoreHide);
            } else {
                $pageRepository = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Frontend\Page\PageRepository::class);
                $GLOBALS['TSFE']->includeTCA();
                return $pageRepository->enableFields($table, $ignoreHide);
            }
        } elseif (TYPO3_MODE === 'BE') {
            return \TYPO3\CMS\Backend\Utility\BackendUtility::deleteClause($table);
        } else {
            self::devLog('Unexpected TYPO3_MODE "'.TYPO3_MODE.'"', DEVLOG_SEVERITY_ERROR);
            return ' AND 1=-1';
        }
    }

    /**
     * This is a static class, thus no instances should be created
     *
     * @access private
     */
    private function __construct()
    {}
}