<?php
/**
 * Orange Management
 *
 * PHP Version 7.0
 *
 * @category   TBD
 * @package    TBD
 * @author     OMS Development Team <dev@oms.com>
 * @author     Dennis Eichhorn <d.eichhorn@oms.com>
 * @copyright  2013 Dennis Eichhorn
 * @license    OMS License 1.0
 * @version    1.0.0
 * @link       http://orange-management.com
 */
namespace phpOMS\Validation;

class BitcoinValidator
{
    public static function validate(string $addr)  : bool
    {
        $decoded = self::decodeBase58($addr);

        $d1 = hash("sha256", substr($decoded, 0, 21), true);
        $d2 = hash("sha256", $d1, true);

        if (substr_compare($decoded, $d2, 21, 4)) {
            return false;
        }

        return true;
    }

    public static function decodeBase58(string $input) : string
    {
        $alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";

        $out = array_fill(0, 25, 0);
        $len = strlen($input);

        for ($i = 0; $i < $len; $i++) {
            if (($p = strpos($alphabet, $input[$i])) === false) {
                throw new \Exception("invalid character found");
            }

            $c = $p;
            for ($j = 25; $j--;) {
                $c += (int) (58 * $out[$j]);
                $out[$j] = (int) ($c % 256);
                $c /= 256;
                $c = (int) $c;
            }

            if ($c !== 0) {
                throw new \Exception("address too long");
            }
        }

        $result = "";
        foreach ($out as $val) {
            $result .= chr($val);
        }

        return $result;
    }
}