using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace GFGGame
{
    public static class AesEncryption
    {
        // !!!重要警告!!!
        // 硬编码在客户端的密钥并不安全，容易被反编译获取。
        // 这只能防止简单的窥探，无法抵御专业黑客。
        // 对于极度敏感的信息，请考虑其他方案（如服务端令牌验证）。
        private static readonly string Key = "45418100000000000000000000000000"; // 必须恰好是32字节
        private static readonly string IV = "1234567890123456"; // 必须恰好是16字节

        public static string Encrypt(string plainText)
        {
            using (Aes aesAlg = Aes.Create())
            {
                aesAlg.Key = Encoding.UTF8.GetBytes(Key);
                aesAlg.IV = Encoding.UTF8.GetBytes(IV);

                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {
                            swEncrypt.Write(plainText);
                        }
                    }

                    return Convert.ToBase64String(msEncrypt.ToArray());
                }
            }
        }

        public static string Decrypt(string cipherText)
        {
            try
            {
                byte[] buffer = Convert.FromBase64String(cipherText);
                using (Aes aesAlg = Aes.Create())
                {
                    aesAlg.Key = Encoding.UTF8.GetBytes(Key);
                    aesAlg.IV = Encoding.UTF8.GetBytes(IV);

                    ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
                    using (MemoryStream msDecrypt = new MemoryStream(buffer))
                    {
                        using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                        {
                            using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                            {
                                return srDecrypt.ReadToEnd();
                            }
                        }
                    }
                }
            }
            catch
            {
                // 解密失败（可能数据被篡改或密钥错误）
                return null;
            }
        }
    }
}