using System.Security.Cryptography;
using System.Text;
namespace Project.Persistence;

public class Crypto
{
    private static readonly string _key = "myKeyIsSecureAsFuck"; 
    
    public static string EncryptPassword(string password)
    {
        using (Aes aes = Aes.Create())
        {
            byte[] key = DeriveKey(_key);
            aes.Key = key;
            aes.GenerateIV(); // generate new IV
            
            ICryptoTransform encryptor = aes.CreateEncryptor();
            
            using (MemoryStream msEncrypt = new MemoryStream())
            {
                // save IV
                msEncrypt.Write(aes.IV, 0, aes.IV.Length);
                
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                {
                    swEncrypt.Write(password);
                }
                
                return Convert.ToBase64String(msEncrypt.ToArray());
            }
        }
    }
    
    public static string DecryptPassword(string encryptedPassword)
    {
        byte[] fullCipher = Convert.FromBase64String(encryptedPassword);
        
        using (Aes aes = Aes.Create())
        {
            byte[] key = DeriveKey(_key);
            aes.Key = key;
            
            // extract IV from encryption
            byte[] iv = new byte[aes.BlockSize / 8];
            Array.Copy(fullCipher, 0, iv, 0, iv.Length);
            aes.IV = iv;
            
            ICryptoTransform decryptor = aes.CreateDecryptor();
            
            using (MemoryStream msDecrypt = new MemoryStream(fullCipher, iv.Length, fullCipher.Length - iv.Length))
            using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
            using (StreamReader srDecrypt = new StreamReader(csDecrypt))
            {
                return srDecrypt.ReadToEnd();
            }
        }
    }
    
    private static byte[] DeriveKey(string key)
    {
        // 256 bits for AES-256
        using (var deriveBytes = new Rfc2898DeriveBytes(key, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 }, 1000))
        {
            return deriveBytes.GetBytes(32); 
        }
    }
}