<?php
namespace app\index\controller;
use app\index\model\ShortUrlModel;
use app\index\service\HelperService;
use think\Controller;
use think\Validate;

class ShortUrl extends CmsController
{
    public function index(){

        $params = $this->request->param();
        $rule = [
            'old_url'=>'require'
        ];
        $validate = new Validate($rule);
        if(!$validate->check($params)){
            HelperService::returnJson([
                'code'=>400,
                'msg'=>$validate->getError(),
                'data'=>""
            ]);
        }


        $num = 0;
        $flag = 'NEW';
        while(true){
            $shortUrlModel =  new ShortUrlModel();
            $res = $shortUrlModel->where(['old_url'=>"{$params['old_url']}"])->find();
            if($res){
                $url_str = $res['url_str'];
                $flag = 'OLD';
                break;
            }
            $random = rand(0,9999);
            $random = str_pad($random,4,'0',STR_PAD_LEFT);
            $url_str = $this->createShortUrl("{$params['old_url']}",$random);
            //首先看库里有没有没有插入
            $res = $shortUrlModel->where(['url_str'=>"{$url_str}"])->find();
            if(empty($res)){
                break;
            }
            $num++;
        }

        if('NEW' == $flag){
            $shortUrlModel =  new ShortUrlModel();
            $shortUrlModel->insert([
                'old_url'=>"{$params['old_url']}",
                'url_str'=>"{$url_str}",
                'num'=>$num,
            ]);
        }

        HelperService::returnJson([
            'code'=>200,
            'msg'=>"http://{$_SERVER['HTTP_HOST']}?to={$url_str}",
            'data'=>$flag
        ]);
    }

    private function createShortUrl($or_url,$salt){

        $md5_url   = md5($or_url);
        //$salt      = '0826';//这里不高于aaaa就不会出现61以上的数字，所以来说，后面的特别符号是不会出现的！
        $md5_url   = $this->addSalt($md5_url,$salt);
        $short_url = '';

        for($i=0;$i<6;$i++){
            $current_str = substr($md5_url,$i*6,6);
            //处理当前串的值
            $short_url .= $this->ZChar($current_str);
        }

        return $short_url;
    }

    /**
     * 处理字符串
     * @param $str
     * @return int
     */
    private function dealStr($str){
        if(strlen($str) != 6){
            die("dealStr:{$str}error");
        }
        $count = '';
        for($i=0;$i<6;$i++){
            //加权,避免不同序列的和一致
            $number = hexdec($str[$i])*($i+1)%12;
            $count += $number;
        }

        return $count % 66;
    }

    /**
     * 字码表
     * @param $char_point
     * @return mixed
     */
    private function char($char_point){

        $char_array = ["0","1","2","3","4","5",
            "6","7","8","9","a","b","c","d",
            "e","f","g","h","i","j","k","l",
            "m","n","o","p","q","r","s","t",
            "u","v","w","x","y","z","A","B",
            "C","D","E","F","G","H","I","J",
            "K","L","M","N","O","P","Q","R",
            "S","T","U","V","W","X","Y","Z",
            "$","@",'+',"="];
        $char_point = intval($char_point);
        if($char_point < 0 || $char_point > 65){
            die('char:'.$char_point.' error');
        }

        return $char_array[$char_point];
    }

    /**
     * 添加盐
     * @param $md5_url
     * @param $salt
     * @return string
     */
    private function addSalt($md5_url,$salt){
        if(strlen($md5_url) != 32){
            die('addSalt:{$md5_url} error');
        }
        $len  = strlen($salt);
        for($i=0;$i<$len;$i++){
            $position = hexdec($md5_url[$i]);
            $weight   = ceil($position/8);
            $position = $position * $weight;
            $pre      = substr($md5_url,0,$position);
            $next     = substr($md5_url,$position);
            $md5_url  = $pre.$salt[$i].$next;
        }
        return $md5_url;
    }

    /**
     * 加密字节
     * @param $current_str
     * @return mixed
     */
    private function ZChar($current_str){
        $Vchar = $this->dealStr($current_str);
        return $this->char($Vchar);
    }
}