<?php
//设置时区
date_default_timezone_set("Asia/Shanghai");
//定义TOKEN常量，这里的"weixin"就是在公众号里配置的TOKEN
define("TOKEN", "test_service");

require_once("Utils.php");
//打印请求的URL查询字符串到query.xml
Utils::traceHttp();

$wechatObj = new wechatCallBackapiTest();
/**
 * 如果有"echostr"字段，说明是一个URL验证请求，
 * 否则是微信用户发过来的信息
 */
if (isset($_GET["echostr"])){
    $wechatObj->valid();
}else {
    $wechatObj->responseMsg();
}

class wechatCallBackapiTest
{
    /**
     * 用于微信公众号里填写的URL的验证，
     * 如果合格则直接将"echostr"字段原样返回
     */
    public function valid()
    {
        $echoStr = $_GET["echostr"];
        if ($this->checkSignature()){
            echo $echoStr;
            exit;
        }
    }

    /**
     * 用于验证是否是微信服务器发来的消息
     * @return bool
     */
    private function checkSignature()
    {
        $signature = $_GET["signature"];
        $timestamp = $_GET["timestamp"];
        $nonce = $_GET["nonce"];

        $token = TOKEN;
        $tmpArr = array($token, $timestamp, $nonce);
        sort($tmpArr);
        $tmpStr = implode($tmpArr);
        $tmpStr = sha1($tmpStr);

        if ($tmpStr == $signature){
            return true;
        }else {
            return false;
        }
    }

    /**
     * 响应用户发来的消息
     */
    public function responseMsg()
    {
        //获取post过来的数据，它一个XML格式的数据
        $postStr = $GLOBALS["HTTP_RAW_POST_DATA"];
        //将数据打印到log.xml
        Utils::logger($postStr);
        if (!empty($postStr)){
            //将XML数据解析为一个对象
            $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
            $RX_TYPE = trim($postObj->MsgType);
            //消息类型分离
            switch($RX_TYPE){
                case "event":
                    $result = $this->receiveEvent($postObj);
                    break;
                default:
                    $result = "unknow msg type:".$RX_TYPE;
                    break;
            }
            //打印输出的数据到log.xml
            Utils::logger($result, '公众号');
            echo $result;
        }else{
            echo "";
            exit;
        }
    }

    /**
     * 接收事件消息
     */
    private function receiveEvent($object)
    {
        switch ($object->Event){
            //关注公众号事件
            case "subscribe":
                $content = "欢迎关注";
                break;
            default:
                $content = "";
                break;
        }
        $result = $this->transmitText($object, $content);
        return $result;
    }

    /**
     * 回复文本消息
     */
    private function transmitText($object, $content)
    {
        $xmlTpl = "<xml>
    <ToUserName><![CDATA[%s]]></ToUserName>
    <FromUserName><![CDATA[%s]]></FromUserName>
    <CreateTime><![CDATA[%s]]></CreateTime>
    <MsgType><![CDATA[text]]></MsgType>
    <Content><![CDATA[%s]]></Content>
</xml>";
        $result = sprintf($xmlTpl, $object->FromUserName, $object->ToUserName, time(), $content);
        return $result;
    }
}