dice.php

<?php

class Dice
{
    protected $json;
    protected $hex;

    /**
     * This sets how many hex characters to use for the length of the number
     *
     *  1 = 0-15
     *  2 = 0-255
     *  3 = 0-4096
     *  4 = 0-65535 -- this
     *  5 = 0-1048575
     *  6 = 0-16777215
     */

    protected $length;


    public function __construct($length = null)
    {
        if (is_null($length)) {
            $length = 4;
        }
        $this->length = $length;
        $this->getJson();
        $this->processNumbers();
    }

    protected function getJson()
    {
        if (!file_exists('numbers.json')) {
            echo "Aquiring new random numbers" . PHP_EOL;
            $data = file_get_contents('https://qrng.anu.edu.au/API/jsonI.php?length=1024&type=hex16&size=1024');
            file_put_contents('numbers.json', $data);
            $this->json = json_decode($data);
        }
        {
            $this->json = json_decode(file_get_contents('numbers.json'));
        }
        return $this->json;
    }

    protected function processNumbers()
    {
        if (!file_exists('numbers.data')) {
            $this->hex = implode($this->json->data);

            $this->hex = str_split($this->hex, $this->length);

            foreach ($this->hex as $key => $value) {
                $this->hex[$key] = hexdec($value);
            }

            file_put_contents('numbers.data', serialize($this->hex));
        } else {
            $this->hex = unserialize(file_get_contents('numbers.data'));
            if (empty($this->hex)) {
                unlink('numbers.data');
                unlink('numbers.json');
                $this->getJson();
                $this->processNumbers();
            }
        }
        return $this->hex;
    }

    public function getNumber()
    {
        if (count($this->hex) == 0) {
            $this->processNumbers();
        }
        $number = array_shift($this->hex);
        file_put_contents('numbers.data', serialize($this->hex));

        return $number;
    }

    public function rand($min = null, $max = null)
    {
        if (!is_null($max) && $max > $this->rand_max()) {
            throw new Exception("Max cannot be greater then " . $this->rand_max(), 1);
        }

        if (!is_null($min) && $min > $this->rand_max()) {
            throw new Exception("Min cannot be greater then " . $this->rand_max(), 1);
        }

        if (!is_null($min) && !is_null($max)) {
            $counts = [];
            $count = 0;
            for ($i = $min; $i <= $max; $i++) {
                $counts[$count] = $i;
                $count++;
            }
            $countKey = $this->getNumber() % $sides;
            $value = $counts[$countKey];
            return $value;
        } else {
            return $this->getNumber();
        }
    }

    public function rand_max()
    {
        $str = "";
        for ($i=1; $i <= $this->length ; $i++) {
            $str .= "f";
        }
        return hexdec($str);
    }

    public function roll($sides)
    {
        return ($this->getNumber() % $sides)+1;
    }
}

$dice = new Dice();

for ($i=0; $i < 100; $i++) {
    print_r($dice->roll(20));
    echo PHP_EOL;
}