package cn.mb.cloud.auth.security.util;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.auth0.jwk.Jwk;
import io.jsonwebtoken.*;
import org.apache.commons.codec.binary.Base64;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.client.RestTemplate;

import java.security.PublicKey;

public class AppleUtil {

    private static final Logger logger = LoggerFactory.getLogger(AppleUtil.class);

    /**
     * 获取苹果的公钥
     *
     * @return
     * @throws Exception
     */
    private static JSONArray getAuthKeys() throws Exception {
        String url = "https://appleid.apple.com/auth/keys";
        RestTemplate restTemplate = new RestTemplate();
        String token = restTemplate.getForObject(url, String.class);
        JSONObject json = JSONObject.parseObject(token);
        JSONArray arr = json.getJSONArray("keys");
        return arr;
    }

    public static Boolean verify(String jwt) throws Exception {
        JSONArray arr = getAuthKeys();
        if (arr == null) {
            return false;
        }
        JSONObject authKey = null;

        //先取苹果第一个key进行校验
        authKey = JSONObject.parseObject(arr.getString(0));
        if (verifyExc(jwt, authKey)) {
            return true;
        } else {
            //再取第二个key校验
            authKey = JSONObject.parseObject(arr.getString(1));
            return verifyExc(jwt, authKey);
        }

    }

    /**
     * 对前端传来的identityToken进行验证
     *
     * @param jwt     对应前端传来的 identityToken
     * @param authKey 苹果的公钥 authKey
     * @return
     * @throws Exception
     */
    public static Boolean verifyExc(String jwt, JSONObject authKey) throws Exception {

        Jwk jwa = Jwk.fromValues(authKey);
        PublicKey publicKey = jwa.getPublicKey();

        String aud = "";
        String sub = "";
        if (jwt.split("\\.").length > 1) {
            String claim = new String(Base64.decodeBase64(jwt.split("\\.")[1]));
            aud = JSONObject.parseObject(claim).get("aud").toString();
            sub = JSONObject.parseObject(claim).get("sub").toString();
        }
        JwtParser jwtParser = Jwts.parser().setSigningKey(publicKey);
        jwtParser.requireIssuer("https://appleid.apple.com");
        jwtParser.requireAudience(aud);
        jwtParser.requireSubject(sub);

        try {
            Jws<Claims> claim = jwtParser.parseClaimsJws(jwt);
            if (claim != null && claim.getBody().containsKey("auth_time")) {
                System.out.println(claim);
                return true;
            }
            return false;
        } catch (ExpiredJwtException e) {
            logger.error("apple identityToken expired", e);
            return false;
        } catch (Exception e) {
            logger.error("apple identityToken illegal", e);
            return false;
        }
    }


    /**
     * 对前端传来的JWT字符串identityToken的第二部分进行解码
     * 主要获取其中的aud和sub，aud大概对应ios前端的包名，sub大概对应当前用户的授权的openID
     *
     * @param identityToken
     * @return {"aud":"com.xkj.****","sub":"000***.8da764d3f9e34d2183e8da08a1057***.0***","c_hash":"UsKAuEoI-****",
     * "email_verified":"true","auth_time":1574673481,"iss":"https://appleid.apple.com",
     * "exp":1574674081,"iat":1574673481,"email":"****@qq.com"}
     */
    public static JSONObject parserIdentityToken(String identityToken) {
        String[] arr = identityToken.split("\\.");
        Base64 base64 = new Base64();
        String decode = new String(base64.decodeBase64(arr[1]));
        String substring = decode.substring(0, decode.indexOf("}") + 1);
        JSONObject jsonObject = JSON.parseObject(substring);
        return jsonObject;
    }
}