<?php
class wxApi{
	const APPID = '';
	const APPSECRET = '';
	const CURL_PROXY_HOST = "0.0.0.0";//"10.152.18.220";
	const CURL_PROXY_PORT = 0;//8080;
	/**
	 * 
	 * 网页授权接口微信服务器返回的数据，返回样例如下
	 * {
	 *  "access_token":"ACCESS_TOKEN",
	 *  "expires_in":7200,
	 *  "refresh_token":"REFRESH_TOKEN",
	 *  "openid":"OPENID",
	 *  "scope":"SCOPE",
	 *  "unionid": "o6_bmasdasdsad6_2sgVt7hMZOPfL"
	 * }
	 * 其中access_token可用于获取共享收货地址
	 * openid是微信支付jsapi支付接口必须的参数
	 * @var array
	 */
	public $data = null;
	/**
	 * 
	 * 通过跳转获取用户的openid，跳转流程如下：
	 * 1、设置自己需要调回的url及其其他参数，跳转到微信服务器https://open.weixin.qq.com/connect/oauth2/authorize
	 * 2、微信服务处理完成之后会跳转回用户redirect_uri地址，此时会带上一些参数，如：code
	 * 
	 * @return 用户的openid
	 */
	public function GetOpenid(){
		//通过code获得openid
		if (!isset($_GET['code'])){
			//触发微信返回code码
			$baseUrl = urlencode('http://'.$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF'].$_SERVER['QUERY_STRING']);
			$url = $this->__CreateOauthUrlForCode($baseUrl);
			Header("Location: $url");
			exit();
		} else {
			//获取code码，以获取openid
		    $code = $_GET['code'];
			$openid = $this->getOpenidFromMp($code);
			return $openid;
		}
	}

	
	/**
	 * 
	 * 通过code从工作平台获取openid机器access_token
	 * @param string $code 微信跳转回来带上的code
	 * 
	 * @return openid
	 */
	public function GetOpenidFromMp($code){
		$url = $this->__CreateOauthUrlForOpenid($code);
		//初始化curl
		$ch = curl_init();
		//设置超时
		curl_setopt($ch, CURLOPT_TIMEOUT, 30);
		curl_setopt($ch, CURLOPT_URL, $url);
		curl_setopt($ch, CURLOPT_SSL_VERIFYPEER,FALSE);
		curl_setopt($ch, CURLOPT_SSL_VERIFYHOST,FALSE);
		curl_setopt($ch, CURLOPT_HEADER, FALSE);
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
		if(self::CURL_PROXY_HOST != "0.0.0.0" 
			&& self::CURL_PROXY_PORT != 0){
			curl_setopt($ch,CURLOPT_PROXY, self::CURL_PROXY_HOST);
			curl_setopt($ch,CURLOPT_PROXYPORT, self::CURL_PROXY_PORT);
		}
		//运行curl，结果以jason形式返回
		$res = curl_exec($ch);
		curl_close($ch);
		//取出openid
		$data = json_decode($res,true);
		$this->data = $data;
		$openid = $data['openid'];
		return $openid;
	}
	/**
	 * 
	 * 拼接签名字符串
	 * @param array $urlObj
	 * 
	 * @return 返回已经拼接好的字符串
	 */
	private function ToUrlParams($urlObj){
		$buff = "";
		foreach ($urlObj as $k => $v){
			if($k != "sign"){
				$buff .= $k . "=" . $v . "&";
			}
		}
		$buff = trim($buff, "&");
		return $buff;
	}
	/**
	 * 
	 * 构造获取code的url连接
	 * @param string $redirectUrl 微信服务器回跳的url，需要url编码
	 * 
	 * @return 返回构造好的url
	 */
	private function __CreateOauthUrlForCode($redirectUrl){
		$urlObj["appid"] = self::APPID;
		$urlObj["redirect_uri"] = "$redirectUrl";
		$urlObj["response_type"] = "code";
		$urlObj["scope"] = "snsapi_base";
		$urlObj["state"] = "STATE"."#wechat_redirect";
		$bizString = $this->ToUrlParams($urlObj);
		return "https://open.weixin.qq.com/connect/oauth2/authorize?".$bizString;
	}
	
	/**
	 * 
	 * 构造获取open和access_toke的url地址
	 * @param string $code，微信跳转带回的code
	 * 
	 * @return 请求的url
	 */
	private function __CreateOauthUrlForOpenid($code){
		$urlObj["appid"] = self::APPID;
		$urlObj["secret"] = self::APPSECRET;
		$urlObj["code"] = $code;
		$urlObj["grant_type"] = "authorization_code";
		$bizString = $this->ToUrlParams($urlObj);
		return "https://api.weixin.qq.com/sns/oauth2/access_token?".$bizString;
	}
}//wxApi
/*
$tools = new wxApi();
$openId = $tools->GetOpenid();
echo $openId;
*/