using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace MV485.util
{

    public class AesEncryptionHelper
    {
        // 定义一个静态的密钥和初始化向量(IV)，这两个值应该保密并且保持不变。
        //private static readonly byte[] Key = Encoding.UTF8.GetBytes("Your16ByteKeyHere!"); // 16, 24, or 32 bytes for AES-128, AES-192, or AES-256
        //private static readonly byte[] IV = Encoding.UTF8.GetBytes("Your16ByteIVHere!");   // 必须是16字节

        public static string key = "bjhcxd@aitest$tool!s"; // 密钥可以是任意长度，但会自动填充到 32 字节

        // AES 加密方法
        public static string EncryptString(string plainText, string key)
        {
            using (Aes aesAlg = Aes.Create())
            {
                // 设置密钥和生成随机的 IV
                byte[] keyBytes = Encoding.UTF8.GetBytes(key.PadRight(32, '0').Substring(0, 32)); // 确保密钥长度为 32 字节
                aesAlg.Key = keyBytes;
                aesAlg.GenerateIV(); // 生成随机的 IV

                // 创建加密器
                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

                // 将明文转换为字节数组
                byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);

                // 使用内存流进行加密
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    // 写入 IV 到输出流
                    msEncrypt.Write(BitConverter.GetBytes(aesAlg.IV.Length), 0, sizeof(int));
                    msEncrypt.Write(aesAlg.IV, 0, aesAlg.IV.Length);

                    // 使用加密器加密数据
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                    {
                        swEncrypt.Write(plainText);
                    }

                    // 返回加密后的数据作为 Base64 字符串
                    return Convert.ToBase64String(msEncrypt.ToArray());
                }
            }
        }

        // AES 解密方法
        public static string DecryptString(string cipherText, string key)
        {
            using (Aes aesAlg = Aes.Create())
            {
                // 设置密钥
                byte[] keyBytes = Encoding.UTF8.GetBytes(key.PadRight(32, '0').Substring(0, 32)); // 确保密钥长度为 32 字节
                aesAlg.Key = keyBytes;

                // 将 Base64 编码的密文转换为字节数组
                byte[] cipherTextBytes = Convert.FromBase64String(cipherText);

                // 从密文中提取 IV
                int ivLength = BitConverter.ToInt32(cipherTextBytes, 0);
                byte[] iv = new byte[ivLength];
                Array.Copy(cipherTextBytes, sizeof(int), iv, 0, ivLength);
                aesAlg.IV = iv;

                // 创建解密器
                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

                // 使用内存流进行解密
                using (MemoryStream msDecrypt = new MemoryStream(cipherTextBytes, sizeof(int) + ivLength, cipherTextBytes.Length - sizeof(int) - ivLength))
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                {
                    // 返回解密后的字符串
                    return srDecrypt.ReadToEnd();
                }
            }
        }


        //-----------------------------------------------------------------------------
    }
}