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

namespace OssTJiaUploaderService
{
    public static class CryptoHelper
    {
        private static readonly string _key = EnvReader.GetMachineVariable("ENC_AES_KEY");
        private static readonly string _iv = EnvReader.GetMachineVariable("ENC_AES_IV");

        public static string Decrypt(string input)
        {
            if (!input.StartsWith("ENC(") || !input.EndsWith(")"))
                return input;

            var base64 = input[4..^1];
            using var aes = Aes.Create();
            aes.Key = Encoding.UTF8.GetBytes(_key);
            aes.IV = Encoding.UTF8.GetBytes(_iv);
            var decryptor = aes.CreateDecryptor();

            var buffer = Convert.FromBase64String(base64);
            var result = decryptor.TransformFinalBlock(buffer, 0, buffer.Length);
            return Encoding.UTF8.GetString(result);
        }

        public static string Encrypt(string plainText)
        {
            using var aes = Aes.Create();
            aes.Key = Encoding.UTF8.GetBytes(_key);
            aes.IV = Encoding.UTF8.GetBytes(_iv);
            var encryptor = aes.CreateEncryptor();

            var bytes = Encoding.UTF8.GetBytes(plainText);
            var encrypted = encryptor.TransformFinalBlock(bytes, 0, bytes.Length);
            return $"ENC({Convert.ToBase64String(encrypted)})";
        }
    }

}