Capitalize an string to correct format

capitalize.php

<?php    

    /**
     * Capitalize an string|array
     * Ex: Fred El BRAVO => Fred el Bravo
     *     Empresa Xpto s/a => Empresa Xpto S/A
     *
     * @param string|array $input
     * @param array $exclude {If passed an array, exclude any element}
     *
     * @return string|array
     */
    function capitalize($input, $exclude = [])
    {
        if (is_array($input)) {
            $fn = function (&$value, $key) use ($exclude) {
                $value = !in_array($key, $exclude) ? capitalize($value) : $value;
            };
            array_walk(
                $input,
                $fn
            );
            return $input;
        } else {
            $arr = [
                'da' => 'da', 'das' => 'das', 'de' => 'de', 'di' => 'di', 'do' => 'do', 'dos' => 'dos', 'e' => 'e', 'el' => 'el',
                'i'  => 'I', 'ii' => 'II', 'iii' => 'III', 'iv' => 'IV', 'v' => 'V', 'vi' => 'VI', 'vii' => 'VII', 'viii' => 'VIII',
                'ix' => 'IX', 'x' => 'X', 'xi' => 'XI', 'xii' => 'XII', 'xiii' => 'XIII', 'a/c' => 'A/C', 'ltda' => 'LTDA',
                'me' => 'ME', 'eireli' => 'EIRELI', 'epp' => 'EPP', 's/a' => 'S/A', 's.a' => 'S/A', 's.a.' => 'S/A',
            ];
            $fn = function ($word) use ($arr) {
                return (!array_key_exists($word, $arr)) ? mb_convert_case(trim($word), MB_CASE_TITLE, 'utf-8') : $arr[$word];
            };
            return join(' ',
                array_map(
                    $fn,
                    explode(
                        ' ',
                        mb_strtolower(trim($input), 'utf-8')
                    )
                )
            );
        }
    }