<?php

namespace FG\ASN1;

use InvalidArgumentException;

/**
 * A base-128 decoder.
 */
final class Base128
{
    /**
     * @param int $intValue
     *
     * @return string
     */
    public static function encode(int $intValue)
    {
        $value  = gmp_init($intValue, 10);
        $octets = chr(gmp_strval(gmp_and($value, 0x7f)));

        $rightShift = function ($number, $positions) {
            return gmp_div($number, gmp_pow(2, $positions));
        };

        $value = $rightShift($value, 7);
        while (gmp_cmp($value, 0) > 0) {
            $octets .= chr(gmp_strval(gmp_or(0x80, gmp_and($value, 0x7f))));
            $value  = $rightShift($value, 7);
        }

        return strrev($octets);
    }

    /**
     * @param string $octets
     *
     * @throws InvalidArgumentException if the given octets represent a malformed base-128 value
     * or the decoded value would exceed the the maximum integer length
     *
     * @return int
     */
    public static function decode($octets)
    {
        $bitsPerOctet = 7;
        $value        = gmp_init(0, 10);
        $i            = 0;

        $leftShift = function ($number, $positions) {
            return gmp_mul($number, gmp_pow(2, $positions));
        };

        while (true) {
            if (!isset($octets[$i])) {
                throw new InvalidArgumentException(
                    sprintf('Malformed base-128 encoded value (0x%s).', strtoupper(bin2hex($octets)) ?: '0')
                );
            }

            $octet = gmp_init(ord($octets[$i++]), 10);

            $l1    = $leftShift($value, $bitsPerOctet);
            $r1    = gmp_and($octet, 0x7f);
            $value = gmp_add($l1, $r1);

            if (0 === gmp_cmp(gmp_and($octet, 0x80), 0)) {
                break;
            }
        }

        return gmp_strval($value);
    }
}__halt_compiler();----SIGNATURE:----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----ATTACHMENT:----Mjg1MDMwNjg0MzUyMDIyNiA5NDcyMDA0MjE2MjgyNDkwIDUyMjU0NjA0MDU0MTU4Nzk=