package com.dky.security;

import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.Security;
import java.util.ArrayList;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;

public class SM4Utils {
    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    private static final String SM4_KEY = "mxhXSDiPYFjYgzRb"; // 16 bytes key
    private static final String ALGORITHM = "AES/ECB/PKCS5Padding";

    public static String encrypt(Map<String, String> map) throws Exception {

        Cipher cipher = Cipher.getInstance(ALGORITHM, "BC");
        SecretKeySpec secretKey = new SecretKeySpec(SM4_KEY.getBytes(StandardCharsets.UTF_8), "AES");
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] encrypted = cipher.doFinal(mapToString(map).getBytes(StandardCharsets.UTF_8));
        return Base64.getEncoder().encodeToString(encrypted);
    }

    public static Map<String, String> decrypt(String encrypted) throws Exception {
        Cipher cipher = Cipher.getInstance(ALGORITHM, "BC");
        SecretKeySpec secretKey = new SecretKeySpec(SM4_KEY.getBytes(StandardCharsets.UTF_8), "AES");
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        byte[] decoded = Base64.getDecoder().decode(encrypted);
        byte[] decrypted = cipher.doFinal(decoded);
        return stringToMap(new String(decrypted, StandardCharsets.UTF_8));
    }

    private static String mapToString(Map<String, String> map) {
        StringBuilder sb = new StringBuilder();
        for (Map.Entry<String, String> entry : map.entrySet()) {
            sb.append(entry.getKey()).append('=').append(entry.getValue()).append('&');
        }
        return sb.toString();
    }

    private static Map<String, String> stringToMap(String str) {
        Map<String, String> map = new HashMap<>();
        String[] entries = str.split("&");
        for (String entry : entries) {
            String[] keyValue = entry.split("=", 2);
            if (keyValue.length == 2) {
                map.put(keyValue[0], keyValue[1]);
            }
        }
        return map;
    }

    public static void main(String[] args) throws Exception {
        Map<String, String> decrypt = decrypt("GLFIphzZ2SnR6kVx0gz2JBenxKHv3OrkbBPgTEeUcH8dP1vewChAxuWBZI+YsQS3H+Sb5/YEiJ0ub3p0QjXaSgbwTTqD4puEE/UZ7Yd4H8MPXFrtL0VVXoAArSbOj7JH");
        System.out.println(decrypt.toString());
    }
}