package com.hxzk.gps.util.AES;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;
import java.util.Base64;

public class AES {

    private static final String ALGORITHM = "AES";
    private static final String TRANSFORMATION = "AES/CBC/PKCS5Padding";
    private static final String PUBLIC_KEY = "KTbVslm2mvQLoD3p";
    private static final int IV_SIZE = 16; // AES 的 IV 长度为 16 字节

    /**
     * 加密方法
     *
     * @param plainText 明文
     * @return 加密后的 Base64 编码字符串，包含 IV 和密文
     * @throws Exception 异常
     */
    public static String encrypt(String plainText) throws Exception {
        // 生成随机的 IV
        byte[] ivBytes = new byte[IV_SIZE];
        SecureRandom secureRandom = new SecureRandom();
        secureRandom.nextBytes(ivBytes);
        IvParameterSpec iv = new IvParameterSpec(ivBytes);

        byte[] keyBytes = PUBLIC_KEY.getBytes(StandardCharsets.UTF_8);
        SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, ALGORITHM);

        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, iv);

        byte[] encryptedBytes = cipher.doFinal(plainText.getBytes(StandardCharsets.UTF_8));

        // 将 IV 和密文拼接在一起
        byte[] combined = new byte[IV_SIZE + encryptedBytes.length];
        System.arraycopy(ivBytes, 0, combined, 0, IV_SIZE);
        System.arraycopy(encryptedBytes, 0, combined, IV_SIZE, encryptedBytes.length);

        return Base64.getEncoder().encodeToString(combined);
    }

    /**
     * 解密方法
     *
     * @param encryptedText 加密后的 Base64 编码字符串，包含 IV 和密文
     * @return 解密后的明文
     * @throws Exception 异常
     */
    public static String decrypt(String encryptedText) throws Exception {
        // 将空格替换成 = 号
        String replacedText = encryptedText.replace(" ", "+");

        byte[] combined = Base64.getDecoder().decode(replacedText);

        // 提取 IV
        byte[] ivBytes = new byte[IV_SIZE];
        System.arraycopy(combined, 0, ivBytes, 0, IV_SIZE);
        IvParameterSpec iv = new IvParameterSpec(ivBytes);

        // 提取密文
        byte[] encryptedBytes = new byte[combined.length - IV_SIZE];
        System.arraycopy(combined, IV_SIZE, encryptedBytes, 0, encryptedBytes.length);

        byte[] keyBytes = PUBLIC_KEY.getBytes(StandardCharsets.UTF_8);
        SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, ALGORITHM);

        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, iv);

        byte[] decryptedBytes = cipher.doFinal(encryptedBytes);
        return new String(decryptedBytes, StandardCharsets.UTF_8);
    }

    public static void main(String[] args) {
        try {
            // 模拟从请求中获取的参数
            String param1 = "szhang";
            String param2 = "SZhang13439350593";

            // 多次加密相同的参数

                String encryptedParam1 = encrypt(param1);
                String encryptedParam2 = encrypt(param2);
                System.out.println("加密后的 username: " + encryptedParam1);
                System.out.println("加密后的 password: " + encryptedParam2);

                // 解密参数
                String decryptedParam1 = decrypt(encryptedParam1);
                String decryptedParam2 = decrypt(encryptedParam2);
                System.out.println("解密后的 username: " + decryptedParam1);
                System.out.println("解密后的 password: " + decryptedParam2);


        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}