using System.IO;
using System.Security.Cryptography;
using System.Text;
using Microsoft.Extensions.Logging;

namespace Livia.Models;
//from https://www.c-sharpcorner.com/article/encryption-and-decryption-using-a-symmetric-key-in-c-sharp/

public interface IAesOperation
{
    string EncryptString(string key, string plainText);
    string DecryptString(string key, string cipherText);
}

internal class AesOperation(ILogger logger) : IAesOperation
{
    public string EncryptString(string key, string plainText)
    {
        try
        {
            byte[] iv = new byte[16];
            byte[] array;

            using (Aes aes = Aes.Create())
            {
                aes.Key = Encoding.UTF8.GetBytes(key);
                aes.IV = iv;

                ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV);

                using MemoryStream memoryStream = new();
                using CryptoStream cryptoStream = new(memoryStream, encryptor, CryptoStreamMode.Write);
                using (StreamWriter streamWriter = new(cryptoStream))
                {
                    streamWriter.Write(plainText);
                }

                array = memoryStream.ToArray();
            }

            return Convert.ToBase64String(array);
        }
        catch (Exception e)
        {
            logger.LogError(e, "Encrypt failed");
            return string.Empty;
        }
    }

    public string DecryptString(string key, string cipherText)
    {
        try
        {
            byte[] iv = new byte[16];
            byte[] buffer = Convert.FromBase64String(cipherText);

            using Aes aes = Aes.Create();
            aes.Key = Encoding.UTF8.GetBytes(key);
            aes.IV = iv;
            ICryptoTransform decryptor = aes.CreateDecryptor(aes.Key, aes.IV);

            using MemoryStream memoryStream = new(buffer);
            using CryptoStream cryptoStream = new(memoryStream, decryptor, CryptoStreamMode.Read);
            using StreamReader streamReader = new(cryptoStream);
            return streamReader.ReadToEnd();
        }
        catch (Exception e)
        {
            logger.LogError(e, "Decrypt failed");
            return string.Empty;
        }
    }
}