cheKey][$threeChars])
                        &&
                        \strpos($str, $threeChars) !== false
                    ) {
                        // DEBUG
                        //\var_dump($str, $threeChars, $REPLACE_HELPER_CACHE[$cacheKey][$threeChars]);

                        $charDone[$threeChars] = true;
                        $str = \str_replace($threeChars, $REPLACE_HELPER_CACHE[$cacheKey][$threeChars], $str);

                        // DEBUG
                        //\var_dump($str, "\n");
                    }
                }

                foreach ($matches[0] as $keyTmp => $char) {
                    if (isset($matches[0][$keyTmp + 1])) {
                        $twoChars = $matches[0][$keyTmp + 0] . $matches[0][$keyTmp + 1];
                    } else {
                        $twoChars = null;
                    }
                    if (
                        $twoChars
                        &&
                        !isset($charDone[$twoChars])
                        &&
                        isset($REPLACE_HELPER_CACHE[$cacheKey][$twoChars])
                        &&
                        \strpos($str, $twoChars) !== false
                    ) {
                        // DEBUG
                        //\var_dump($str, $twoChars, $REPLACE_HELPER_CACHE[$cacheKey][$twoChars]);

                        $charDone[$twoChars] = true;
                        $str = \str_replace($twoChars, $REPLACE_HELPER_CACHE[$cacheKey][$twoChars], $str);

                        // DEBUG
                        //\var_dump($str, "\n");
                    }
                }
            }

            foreach ($matches[0] as $char) {
                if (
                    !isset($charDone[$char])
                    &&
                    isset($REPLACE_HELPER_CACHE[$cacheKey][$char])
                    &&
                    \strpos($str, $char) !== false
                ) {
                    // DEBUG
                    //\var_dump($str, $char, $REPLACE_HELPER_CACHE[$cacheKey][$char]);

                    $charDone[$char] = true;
                    $str = \str_replace($char, $REPLACE_HELPER_CACHE[$cacheKey][$char], $str);

                    // DEBUG
                    //\var_dump($str, "\n");
                }
            }
        }

        if (!isset(self::$ASCII_MAPS[$language])) {
            $use_transliterate = true;
        }

        if ($use_transliterate) {
            $str = self::to_transliterate($str, null, false);
        }

        if ($remove_unsupported_chars) {
            $str = (string) \str_replace(["\n\r", "\n", "\r", "\t"], ' ', $str);
            $str = (string) \preg_replace('/' . self::$REGEX_ASCII . '/', '', $str);
        }

        return $str;
    }

    /**
     * Convert given string to safe filename (and keep string case).
     *
     * EXAMPLE: <code>
     * ASCII::to_filename('שדגשדג.png', true)); // 'shdgshdg.png'
     * </code>
     *
     * @param string $str               <p>The string input.</p>
     * @param bool   $use_transliterate <p>ASCII::to_transliterate() is used by default - unsafe characters are
     *                                  simply replaced with hyphen otherwise.</p>
     * @param string $fallback_char     <p>The fallback character. - "-" is the default</p>
     *
     * @psalm-pure
     *
     * @return string
     *                <p>A string that contains only safe characters for a filename.</p>
     */
    public static function to_filename(
        string $str,
        bool $use_transliterate = true,
        string $fallback_char = '-'
    ): string {
        if ($use_transliterate) {
            $str = self::to_transliterate($str, $fallback_char);
        }

        $fallback_char_escaped = \preg_quote($fallback_char, '/');

        $str = (string) \preg_replace(
            [
                '/[^' . $fallback_char_escaped . '.\\-a-zA-Z\d\\s]/', // 1) remove un-needed chars
                '/\s+/u',                                             // 2) convert spaces to $fallback_char
                '/[' . $fallback_char_escaped . ']+/u',               // 3) remove double $fallback_char's
            ],
            [
                '',
                $fallback_char,
                $fallback_char,
            ],
            $str
        );

        return \trim($str, $fallback_char);
    }

    /**
     * Converts a string into a URL-friendly slug.
     *
     * - This includes replacing non-ASCII characters with their closest ASCII equivalents, removing remaining
     *   non-ASCII and non-alphanumeric characters, and replacing whitespace with $separator.
     * - The separator defaults to a single dash, and the string is also converted to lowercase.
     * - The language of the source string can also be supplied for language-specific transliteration.
     *
     * @param string                $str                   <p>The string input.</p>
     * @param string                $separator             [optional] <p>The string used to replace whitespace.</p>
     * @param string                $language              [optional] <p>Language of the source string.
     *                                                     (default is 'en') | ASCII::*_LANGUAGE_CODE</p>
     * @param array<string, string> $replacements          [optional] <p>A map of replaceable strings.</p>
     * @param bool                  $replace_extra_symbols [optional] <p>Add some more replacements e.g. "£" with "
     *                                                     pound ".</p>
     * @param bool                  $use_str_to_lower      [optional] <p>Use "string to lower" for the input.</p>
     * @param bool                  $use_transliterate     [optional] <p>Use ASCII::to_transliterate() for unknown
     *                                                     chars.</p>
     * @psalm-pure
     *
     * @return string
     *                <p>The URL-friendly slug.</p>
     *
     * @phpstan-param ASCII::*_LANGUAGE_CODE $language
     */
    public static function to_slugify(
        string $str,
        string $separator = '-',
        string $language = self::ENGLISH_LANGUAGE_CODE,
        array $replacements = [],
        bool $replace_extra_symbols = false,
        bool $use_str_to_lower = true,
        bool $use_transliterate = false
    ): string {
        if ($str === '') {
            return '';
        }

        foreach ($replacements as $from => $to) {
            $str = \str_replace($from, $to, $str);
        }

        $str = self::to_ascii(
            $str,
            $language,
            false,
            $replace_extra_symbols,
            $use_transliterate
        );

        $str = \str_replace('@', $separator, $str);

        $str = (string) \preg_replace(
            '/[^a-zA-Z\\d\\s\\-_' . \preg_quote($separator, '/') . ']/',
            '',
            $str
        );

        if ($use_str_to_lower) {
            $str = \strtolower($str);
        }

        $str = (string) \preg_replace('/^[\'\\s]+|[\'\\s]+$/', '', $str);
        $str = (string) \preg_replace('/\\B([A-Z])/', '-\1', $str);
        $str = (string) \preg_replace('/[\\-_\\s]+/', $separator, $str);

        $l = \strlen($separator);
        if ($l && \strpos($str, $separator) === 0) {
            $str = (string) \substr($str, $l);
        }

        if (\substr($str, -$l) === $separator) {
            $str = (string) \substr($str, 0, \strlen($str) - $l);
        }

        return $str;
    }

    /**
     * Returns an ASCII version of the string. A set of non-ASCII characters are
     * replaced with their closest ASCII counterparts, and the rest are removed
     * unless instructed otherwise.
     *
     * EXAMPLE: <code>
     * ASCII::to_transliterate('déjà σσς iıii'); // 'deja sss iiii'
     * </code>
     *
     * @param string      $str     <p>The input string.</p>
     * @param string|null $unknown [optional] <p>Character use if character unknown. (default is '?')
     *                             But you can also use NULL to keep the unknown chars.</p>
     * @param bool        $strict  [optional] <p>Use "transliterator_transliterate()" from PHP-Intl
     *
     * @psalm-pure
     *
     * @return string
     *                <p>A String that contains only ASCII characters.</p>
     */
    public static function to_transliterate(
        string $str,
        $unknown = '?',
        bool $strict = false
    ): string {
        static $UTF8_TO_TRANSLIT = null;

        static $TRANSLITERATOR = null;

        static $SUPPORT_INTL = null;

        if ($str === '') {
            return '';
        }

        if ($SUPPORT_INTL === null) {
            $SUPPORT_INTL = \extension_loaded('intl');
        }

        // check if we only have ASCII, first (better performance)
        $str_tmp = $str;
        if (self::is_ascii($str)) {
            return $str;
        }

        $str = self::clean($str);

        // check again if we only have ASCII, now ...
        if (
            $str_tmp !== $str
            &&
            self::is_ascii($str)
        ) {
            return $str;
        }

        if (
            $strict
            &&
            $SUPPORT_INTL === true
        ) {
            if (!isset($TRANSLITERATOR)) {
                // INFO: see "*-Latin" rules via "transliterator_list_ids()"
                $TRANSLITERATOR = \transliterator_create('NFKC; [:Nonspacing Mark:] Remove; NFKC; Any-Latin; Latin-ASCII;');
            }

            // INFO: https://unicode.org/cldr/utility/character.jsp
            $str_tmp = \transliterator_transliterate($TRANSLITERATOR, $str);

            if ($str_tmp !== false) {
                // check again if we only have ASCII, now ...
                if (
                    $str_tmp !== $str
                    &&
                    self::is_ascii($str_tmp)
                ) {
                    return $str_tmp;
                }

                $str = $str_tmp;
            }
        }

        if (self::$ORD === null) {
            self::$ORD = self::getData('ascii_ord');
        }

        \preg_match_all('/.|[^\x00]$/us', $str, $array_tmp);
        $chars = $array_tmp[0];
        $ord = null;
        $str_tmp = '';
        foreach ($chars as &$c) {
            $ordC0 = self::$ORD[$c[0]];

            if ($ordC0 >= 0 && $ordC0 <= 127) {
                $str_tmp .= $c;

                continue;
            }

            $ordC1 = self::$ORD[$c[1]];

            // ASCII - next please
            if ($ordC0 >= 192 && $ordC0 <= 223) {
                $ord = ($ordC0 - 192) * 64 + ($ordC1 - 128);
            }

            if ($ordC0 >= 224) {
                $ordC2 = self::$ORD[$c[2]];

                if ($ordC0 <= 239) {
                    $ord = ($ordC0 - 224) * 4096 + ($ordC1 - 128) * 64 + ($ordC2 - 128);
                }

                if ($ordC0 >= 240) {
                    $ordC3 = self::$ORD[$c[3]];

                    if ($ordC0 <= 247) {
                        $ord = ($ordC0 - 240) * 262144 + ($ordC1 - 128) * 4096 + ($ordC2 - 128) * 64 + ($ordC3 - 128);
                    }

                    // We only process valid UTF-8 chars (<= 4 byte), so we don't need this code here ...
                    /*
                    if ($ordC0 >= 248) {
                        $ordC4 = self::$ORD[$c[4]];

                        if ($ordC0 <= 251) {
                            $ord = ($ordC0 - 248) * 16777216 + ($ordC1 - 128) * 262144 + ($ordC2 - 128) * 4096 + ($ordC3 - 128) * 64 + ($ordC4 - 128);
                        }

                        if ($ordC0 >= 252) {
                            $ordC5 = self::$ORD[$c[5]];

                            if ($ordC0 <= 253) {
                                $ord = ($ordC0 - 252) * 1073741824 + ($ordC1 - 128) * 16777216 + ($ordC2 - 128) * 262144 + ($ordC3 - 128) * 4096 + ($ordC4 - 128) * 64 + ($ordC5 - 128);
                            }
                        }
                    }
                     */
                }
            }

            if (
                $ordC0 === 254
                ||
                $ordC0 === 255
                ||
                $ord === null
            ) {
                $str_tmp .= $unknown ?? $c;

                continue;
            }

            $bank = $ord >> 8;
            if (!isset($UTF8_TO_TRANSLIT[$bank])) {
                $UTF8_TO_TRANSLIT[$bank] = self::getDataIfExists(\sprintf('x%03x', $bank));
            }

            $new_char = $ord & 255;

            if (isset($UTF8_TO_TRANSLIT[$bank][$new_char])) {
                // keep for debugging
                /*
                echo "file: " . sprintf('x%02x', $bank) . "\n";
                echo "char: " . $c . "\n";
                echo "ord: " . $ord . "\n";
                echo "new_char: " . $new_char . "\n";
                echo "new_char: " . mb_chr($new_char) . "\n";
                echo "ascii: " . $UTF8_TO_TRANSLIT[$bank][$new_char] . "\n";
                echo "bank:" . $bank . "\n\n";
                 */

                $new_char = $UTF8_TO_TRANSLIT[$bank][$new_char];

                /* @noinspection PhpStatementHasEmptyBodyInspection */
                if ($unknown === null && $new_char === '') {
                    // nothing
                } elseif (
                    $new_char === '[?]'
                    ||
                    $new_char === '[?] '
                ) {
                    $c = $unknown ?? $c;
                } else {
                    $c = $new_char;
                }
            } else {
                // keep for debugging missing chars
                /*
                echo "file: " . sprintf('x%02x', $bank) . "\n";
                echo "char: " . $c . "\n";
                echo "ord: " . $ord . "\n";
                echo "new_char: " . $new_char . "\n";
                echo "new_char: " . mb_chr($new_char) . "\n";
                echo "bank:" . $bank . "\n\n";
                 */

                $c = $unknown ?? $c;
            }

            $str_tmp .= $c;
        }

        return $str_tmp;
    }

    /**
     * WARNING: This method will return broken characters and is only for special cases.
     *
     * Convert a UTF-8 encoded string to a single-byte string suitable for
     * functions that need the same string length after the conversion.
     *
     * The function simply uses (and updates) a tailored dynamic encoding
     * (in/out map parameter) where non-ascii characters are remapped to
     * the range [128-255] in order of appearance.
     *
     * Thus, it supports up to 128 different multibyte code points max over
     * the whole set of strings sharing this encoding.
     *
     * Source: https://github.com/KEINOS/mb_levenshtein
     *
     * @param string $str <p>UTF-8 string to be converted to extended ASCII.</p>
     * @param array  $map <p>Internal-Map of code points to ASCII characters.</p>
     *
     * @return string
     *                <p>Mapped broken string.</p>
     *
     * @phpstan-param array<string, string> $map
     */
    private static function to_ascii_remap_intern(string $str, array &$map): string
    {
        // find all utf-8 characters
        $matches = [];
        if (!\preg_match_all('/[\xC0-\xF7][\x80-\xBF]+/', $str, $matches)) {
            return $str; // plain ascii string
        }

        // update the encoding map with the characters not already met
        $mapCount = \count($map);
        foreach ($matches[0] as $mbc) {
            if (!isset($map[$mbc])) {
                $map[$mbc] = \chr(128 + $mapCount);
                ++$mapCount;
            }
        }

        // finally, remap non-ascii characters
        return \strtr($str, $map);
    }

    /**
     * Get the language from a string.
     *
     * e.g.: de_at -> de_at
     *       de_DE -> de
     *       DE_DE -> de
     *       de-de -> de
     *
     * @return string
     */
    private static function get_language(string $language)
    {
        if ($language === '') {
            return '';
        }

        if (
            \strpos($language, '_') === false
            &&
            \strpos($language, '-') === false
        ) {
            return \strtolower($language);
        }

        $language = \str_replace('-', '_', \strtolower($language));

        $regex = '/(?<first>[a-z]+)_\g{first}/';

        return (string) \preg_replace($regex, '$1', $language);
    }

    /**
     * Get data from "/data/*.php".
     *
     * @return array<array-key,mixed>
     */
    private static function getData(string $file)
    {
        return include __DIR__ . '/data/' . $file . '.php';
    }

    /**
     * Get data from "/data/*.php".
     *
     * @return array<array-key,mixed>
     */
    private static function getDataIfExists(string $file): array
    {
        $file = __DIR__ . '/data/' . $file . '.php';
        if (\is_file($file)) {
            return include $file;
        }

        return [];
    }

    /**
     * @return void
     */
    private static function prepareAsciiAndExtrasMaps()
    {
        if (self::$ASCII_MAPS_AND_EXTRAS === null) {
            self::prepareAsciiMaps();
            self::prepareAsciiExtras();

            self::$ASCII_MAPS_AND_EXTRAS = \array_merge_recursive(
                self::$ASCII_MAPS ?? [],
                self::$ASCII_EXTRAS ?? []
            );
        }
    }

    /**
     * @return void
     */
    private static function prepareAsciiMaps()
    {
        if (self::$ASCII_MAPS === null) {
            self::$ASCII_MAPS = self::getData('ascii_by_languages');
        }
    }

    /**
     * @return void
     */
    private static function prepareAsciiExtras()
    {
        if (self::$ASCII_EXTRAS === null) {
            self::$ASCII_EXTRAS = self::getData('ascii_extras_by_languages');
        }
    }
}