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

namespace WingServerCommon.Config
{
    public class ConfigCrypter
    {
        // Defalt key vector
        private byte[] _keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
        private string _defaultKey = "vinno123";

        /// <summary>
        /// DES encrypt string.
        /// </summary>
        /// <param name="encryptString">String to be encrypted</param>
        /// <param name="encryptKey">encrypt key,8 characters</param>
        /// <returns>Return encrypted string while success，empty string will be return while failed.</returns>
        public string EncryptDES(string encryptString, string encryptKey = "")
        {
            try
            {
                var needEncrypt = !IsBase64Formatted(encryptString);
                if (needEncrypt)
                {
                    encryptKey = string.IsNullOrEmpty(encryptKey) ? _defaultKey : encryptKey;
                    var rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));
                    var rgbIV = _keys;
                    var inputByteArray = Encoding.UTF8.GetBytes(encryptString);
                    var dCSP = new DESCryptoServiceProvider();
                    var mStream = new MemoryStream();
                    var cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                    cStream.Write(inputByteArray, 0, inputByteArray.Length);
                    cStream.FlushFinalBlock();
                    var asdsad = Convert.ToBase64String(mStream.ToArray());
                    return Convert.ToBase64String(mStream.ToArray());
                }
                else
                {
                    return encryptString;
                }
            }
            catch (Exception e)
            {
                Logger.WriteLineError($"Encrypt failed:{e}");
                return string.Empty;
            }
        }

        /// <summary>
        /// DES decrypt string
        /// </summary>
        /// <param name="decryptString">String to be decrypted</param>
        /// <param name="decryptKey">decrypt key,8 characters,same as encrypt key.</param>
        /// <returns>Return decrypted string while success，source string will be return while failed.</returns>
        public string DecryptDES(string decryptString, string decryptKey = "")
        {
            if (string.IsNullOrEmpty(decryptString))
            {
                return string.Empty;
            }
            var needDecrypt = IsBase64Formatted(decryptString);
            if (needDecrypt)
            {
                try
                {
                    decryptKey = string.IsNullOrEmpty(decryptKey) ? _defaultKey : decryptKey;
                    var rgbKey = Encoding.UTF8.GetBytes(decryptKey);
                    var rgbIV = _keys;
                    var inputByteArray = Convert.FromBase64String(decryptString);
                    var DCSP = new DESCryptoServiceProvider();
                    var mStream = new MemoryStream();
                    var cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                    cStream.Write(inputByteArray, 0, inputByteArray.Length);
                    cStream.FlushFinalBlock();
                    var asdasd = Encoding.UTF8.GetString(mStream.ToArray());
                    return Encoding.UTF8.GetString(mStream.ToArray());
                }
                catch (Exception e)
                {
                    Logger.WriteLineError($"decrypt failed:{e}");
                    return decryptString;
                }
            }
            return decryptString;
        }

        private bool IsBase64Formatted(string input)
        {
            try
            {
                Convert.FromBase64String(input);
                return true;
            }
            catch
            {
                return false;
            }
        }
    }
}