<?php 
/**
 * Created by PhpStorm.
 * User: Administrator
 * Date: 2018/1/19/019
 * Time: 17:23
 */

namespace common\helpers;


class BankCardHelper
{
    /**
     * @var BankCardHelper
     */
    private static $_instance;

    /**
     * BankCardHelper constructor.
     */
    private function __construct()
    {
    }
    
    /**
     * 验证银行卡号的正确性luhn算法
     * @param $card_number
     * @return bool
     */
    public function check_bankCard($card_number)
    {
        $arr_no = str_split($card_number);
        $last_n = $arr_no[count($arr_no)-1];
        krsort($arr_no);
        $i = 1;
        $total = 0;
        foreach ($arr_no as $n) {
            if ($i%2 == 0) {
                $ix = $n * 2;
                if ($ix >= 10) {
                    $nx = 1 + ($ix % 10);
                    $total += $nx;
                } else {
                    $total += $ix;
                }
            } else {
                $total += $n;
            }
            $i++;
        }
        $total -= $last_n;
        $x = 10 - ($total % 10);
        if ($x == $last_n) {
            return true;
        } else {
            return false;
        }
    }

    public static function getInstance()
    {
        if (self::$_instance === null) {
            self::$_instance = new self();
        }
        return self::$_instance;
    }
}