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

namespace LFP_Manager.Function
{
    class CsCryptoHelper
    {
        // 고정 키 및 IV (보안상 실제 사용 시 안전하게 관리 필요)
        private static readonly string key = "1234567890123456"; // 16글자 = 128bit
        private static readonly string iv = "6543210987654321";  // 16글자 = 128bit

        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();

                using (MemoryStream msEncrypt = new MemoryStream())
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                {
                    swEncrypt.Write(plainText);
                    swEncrypt.Close();
                    return Convert.ToBase64String(msEncrypt.ToArray());
                }
            }
        }

        public static string Decrypt(string cipherText)
        {
            using (Aes aesAlg = Aes.Create())
            {
                aesAlg.Key = Encoding.UTF8.GetBytes(key);
                aesAlg.IV = Encoding.UTF8.GetBytes(iv);

                ICryptoTransform decryptor = aesAlg.CreateDecryptor();

                byte[] buffer = Convert.FromBase64String(cipherText);

                using (MemoryStream msDecrypt = new MemoryStream(buffer))
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                {
                    return srDecrypt.ReadToEnd();
                }
            }
        }
    }
}