import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.JSONObject;
import lombok.extern.slf4j.Slf4j;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import javax.xml.bind.DatatypeConverter;
import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.TreeMap;

@Slf4j
public class HMACSHA256Util {
    public static void main(String[] args) throws Exception {
        String secretKey = "secret_key";

        String reqJson = "{\"amount\":\"73800\",\"currency\":\"BRL\",\"goodsName\":\"锂电池\",\"merchantId\":\"1840690697213079001\",\"notifyUrl\":\"https://example.com/notify\",\"orderId\":\"1863816181848834001\",\"orderName\":\"展示名字\",\"payer\":{\"document\":\"12345678900\",\"email\":\"s.jycv@qq.com\",\"name\":\"Jack\",\"phoneNumber\":\"+8612345678901\",\"type\":1},\"requestId\":\"1863816181848834001\",\"subMerchantId\":\"1840690697213079002\"}\n";
        System.out.println("排序前待签报文:" + reqJson);

        String sign = sign(reqJson, secretKey);
        System.out.println("签值:" + sign);

        boolean verify = verify(reqJson, secretKey, sign);
        System.out.println("验签结果:" + verify);
    }

    public static String sign(String reqJson, String secretKey) throws NoSuchAlgorithmException, InvalidKeyException {
        // 解析 JSON 字符串为 JSONObject
        JSONObject jsonObject = JSON.parseObject(reqJson);

        // 对 JSONObject 进行排序
        TreeMap<String, Object> sortedParameters = sortJSONObject(jsonObject);

        // 将排序后的 TreeMap 转换为 JSON 字符串
        String jsonString = JSON.toJSONString(sortedParameters);

        // 生成 HMAC-SHA256 签名
        Mac hmacSHA256 = Mac.getInstance("HmacSHA256");
        SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
        hmacSHA256.init(secretKeySpec);
        log.info("排序后待签报文:{}", jsonString);
        byte[] hash = hmacSHA256.doFinal(jsonString.getBytes(StandardCharsets.UTF_8));
        String sign = DatatypeConverter.printBase64Binary(hash);
        log.info("签名:{}", sign);
        return sign;
    }

    // 验证签名的方法
    public static boolean verify(String reqJson, String secretKey, String providedSignature) throws Exception {
        // 生成签名
        String generatedSignature = sign(reqJson, secretKey);

        // 比较生成的签名和提供的签名
        return generatedSignature.equals(providedSignature);
    }

    public static TreeMap<String, Object> sortJSONObject(JSONObject jsonObject) {
        if (jsonObject == null) {
            return null;
        }

        TreeMap<String, Object> sortedMap = new TreeMap<>();
        for (String key : jsonObject.keySet()) {
            Object value = jsonObject.get(key);
            if (value instanceof JSONObject) {
                sortedMap.put(key, sortJSONObject((JSONObject) value));
            } else {
                sortedMap.put(key, value);
            }
        }
        return sortedMap;
    }
}