<?php
/**
 * Created by PhpStorm.
 * User: 0fun
 * Date: 2018/5/10
 * Time: 17:16
 */

class Jssdk
{
    private $appId;
    private $appSecret;
    private $redis;

    public function __construct($group = 'default')
    {
        $CI = & get_instance();
        if(is_array($group)){
            $this->appId = $group['appid'];
            $this->appSecret = $group['appSecret'];
        } else {
            $CI->load->config('wechat');
            $config =$CI->config->item($group);

            $this->appId = $config['appid'];
            $this->appSecret = $config['appSecret'];
        }

        $r = &load_cache('redis');
        $this->redis = $r->redis();

        $param = array('appid' => $this->appId, "secret" => $this->appSecret);
        $CI->load->library("hd_wechat", $param);
        $this->hd_wechat = $CI->hd_wechat;
        $this->hd_wechat->init($param);
    }

    public function getSignPackage()
    {
        $jsapiTicket = $this->getJsApiTicket();
        $url = "https://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";

        if($_SERVER['QUERY_STRING'])
        {
            //$url .= '?'.$_SERVER['QUERY_STRING'];
        }

        $timestamp = time();
        $nonceStr = $this->createNonceStr();

        // 这里参数的顺序要按照 key 值 ASCII 码升序排序
        $string = "jsapi_ticket=$jsapiTicket&noncestr=$nonceStr&timestamp=$timestamp&url=$url";
        $signature = sha1($string);

        $signPackage = array(
            "appId"     => $this->appId,
            "nonceStr"  => $nonceStr,
            "timestamp" => $timestamp,
            "url"       => $url,
            "signature" => $signature,
            "rawString" => $string,
            'jsapi_ticket' => $jsapiTicket
        );

        return $signPackage;
    }

    private function createNonceStr($length = 16)
    {
        $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        $str = "";
        for ($i = 0; $i < $length; $i++)
        {
            $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
        }

        return $str;
    }

    private function getJsApiTicket()
    {
        $ticket = $this->hd_wechat->api_ticket();
        return $ticket;
    }
}