Random Character Permutation

random_char_permutations.php

<?php
/**
 * Create possible random array permutation by characters
 */
function random_array_permutations($array_or_string, int $length, int $max = 10, array $must_be_not_in = []) : array
{
    if (!is_array($array_or_string)) {
        $array_or_string = str_split((string) $array_or_string);
    }
    $count = count($array_or_string);
    if ($count === 0) {
        return [];
    }

    // shuffling to random
    shuffle($array_or_string);
    // make it unique & no equal value
    $array_or_string = array_unique($array_or_string);
    // flipping value as key
    $must_be_not_in = array_flip($must_be_not_in);
    $data = [];
    $possible = pow($max, $length);
    while (count($data) < $max && $possible > 1) {
        $possible--;
        $current = '';
        $e = 0;
        while (strlen($current) < $length) {
            // shuffling to random
            shuffle($array_or_string);
            if (!isset($array_or_string[$e])) {
                $e = 0;
                continue;
            }
            $current .= $array_or_string[$e++];
        }
        // coninue if contains
        if (isset($must_be_not_in[$current])) {
            continue;
        }
        // append as key
        $data[$current] = 0;
    }

    return array_keys($data);
}