MODX output filter to print out the size of a file

fmt.fileSize.php

<?php

/**
 *
 * Example usage: [[*filepath:fmt.fileSize=`mb`]]
 *
 */
$units = array(
    'gb' => array('size' => 1073741824, 'label' => 'GB'),
    'mb' => array('size' => 1048576,    'label' => 'MB'),
    'kb' => array('size' => 1024,       'label' => 'KB'),
    'b'  => array('size' => 0,          'label' => 'bytes')
);
$path = MODX_BASE_PATH . $input;
$size = is_file($path) ? filesize($path) : 0;
$unit = (isset($options) && isset($units[$options])) ? $options : false;
if ($size > 0) {
    if ($unit === false) {
        // If the unit is not specified, detect it automatically.
        foreach ($units as $key => $properties) {
            if ($size >= $properties['size']) {
                $unit = $key;
                break;
            }
        }
    }
    if ($unit != 'b') {
        $size = $size / $units[$unit]['size'];
    }
}
else {
    if ($unit === false) {
        $unit = 'b';
    }
}
return round($size, 2) . ' ' . $units[$unit]['label'];