<?php

/**
 * Generates a random alphanumeric string
 *
 * @return string
 */
private static function generateOrderId()
{
    // most characters, except those that look like others (e.g. o and 0)
    $characters = 'ABCDEFGHJKMNPQRSTUVWXYZ23456789';

    $string = '';
    for ($i = 0; $i < 10; $i++) {
        $string .= $characters[rand(0, strlen($characters) - 1)];
    }

    return $string;
}