/* jwt 库
 * github地址：https://github.com/kelvinmo/simplejwt
 * 假设克隆后文件夹名为：simplejwt-master
 */
<?php
//此处仅加载本需求使用到的文件
require_once "./simplejwt-master/src/SimpleJWT/Crypt/EncryptionAlgorithm.php";
require_once "./simplejwt-master/src/SimpleJWT/Crypt/KeyManagementAlgorithm.php";
require_once "./simplejwt-master/src/SimpleJWT/Crypt/Algorithm.php";
require_once "./simplejwt-master/src/SimpleJWT/Crypt/KeyEncryptionAlgorithm.php";
require_once "./simplejwt-master/src/SimpleJWT/Crypt/AESCBC_HMACSHA2.php";
require_once "./simplejwt-master/src/SimpleJWT/Crypt/AESKeyWrap.php";
require_once "./simplejwt-master/src/SimpleJWT/Crypt/AlgorithmFactory.php";
require_once "./simplejwt-master/src/SimpleJWT/JWE.php";
require_once "./simplejwt-master/src/SimpleJWT/Keys/KeySet.php";
require_once "./simplejwt-master/src/SimpleJWT/Util/Util.php";
require_once "./simplejwt-master/src/SimpleJWT/Keys/Key.php";
require_once "./simplejwt-master/src/SimpleJWT/Crypt/CryptException.php";
require_once "./simplejwt-master/src/SimpleJWT/InvalidTokenException.php";
require_once "./simplejwt-master/src/SimpleJWT/Keys/SymmetricKey.php";
require_once "./simplejwt-master/src/SimpleJWT/Crypt/KeyDerivationAlgorithm.php";
/* Webhook 基本协议实现
 *
 * 以下代码为示例，未妥善处理业务字段或异常等因素
 */
public function execute(){
    # 配置项，测试时请修改以下配置
    $arrPsks = array("MDEyMzQ1Njc4OWFiY2RlMQ");

    //组建自己的 PSK_TABLE, 可根据自己的需求修改
    $psk_table = array();
    foreach ($arrPsks as $key => $strPsk) {
        $strKey = strval($key);
        $keys = new \SimpleJWT\Keys\KeySet();
        $pskKey = new \SimpleJWT\Keys\SymmetricKey($strPsk, 'base64url');
        $pskKey->setKeyId($strKey);
        $keys->add($pskKey);
        $psk_table[$strKey] = $keys;
    }
    $alg = "A128KW";

    //获取到请求数据
    $token = file_get_contents ('php://input');
    
    //解析请求数据
    $parts = explode('.', $token, 5);
    if (count($parts) != 5) {
        throw new InvalidTokenException('Cannot decode compact serialisation', InvalidTokenException::TOKEN_PARSE_ERROR);
    }
    list($protected, $encrypted_key, $iv, $ciphertext, $tag) = $parts;

    //解析出 header
    $jose_header = json_decode(\SimpleJWT\Util\Util::base64url_decode($protected), true);

    //从 protected 字段中解出来 kid
    $kid = $jose_header['kid'];

    //通过 kid 确定要使用哪个解密 key
    $psk = $psk_table[strval($kid)];

    //用 key 解密取得解密后的内容
    $jwe = \SimpleJWT\JWE::decrypt($token,$psk,$alg);
    $req = json_decode( $jwe->getPlaintext(), true);

    //如果资源方有多张卡片，从 req 中解析出来 srcid,处理相应的业务逻辑
    if ($req['srcid'] == "123"){
        //do something
        $res = array(
            'status' => 0,
            'msg'    => "",
        );
        $res['data'] = array(
            'item_list' => array(
                'title'     => "故宫博物院",
                'jump_url'  => "/path/to/pages3",
            ),
        );
    } else {
        $res = array(
            'status'    => 2,
            'msg'       => "Invalid srcid",
        );
    }

    //处理业务响应结果
    $playload = json_encode($res);

    //用请求的 header 和 key 生成加密结果，保持加密算法和头内容(kid/rid)与请求一致
    $jwe = new \SimpleJWT\JWE($jose_header, $playload);
    $res_body = $jwe->encrypt($psk);

    header("Content-type:application/jwt; charset=UTF-8");
    echo ($res_body);
}