Break a string into n number of equal parts to an array.php

<?php
/**
 * Break a string into 
 * n number of equal 
 * parts to an array
 */

$string = 'This-is-a-long-string-that-has-some-random-text-with-hyphens!';
$string_length = strlen($string);

switch ($string_length) {

  case ($string_length > 0 && $string_length < 21):
    $parts = ceil($string_length / 2); // Break string into 2 parts
    $str_chunks = chunk_split($string, $parts);
    break;

  default:
    $parts = ceil($string_length / 3); // Break string into 3 parts
    $str_chunks = chunk_split($string, $parts);
    break;

}

$string_array = array_filter(explode(PHP_EOL, $str_chunks));