using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.Web;

namespace System
{
    public static class EncryptHelper
    {
        /// <summary>
        /// AES秘钥(强烈要求.json自定义取出)
        /// </summary>
        private const string AesKey = "OwenItc-*&$%RTj3";

        /// <summary>
        /// AES偏移向量(强烈要求.json自定义取出)
        /// </summary>
        private const string AesIV = "*&^KJ8a-Tj3*&$%R";

        public static string AesEncrypt(string toEncryptString)
        {
            return AesEncrypt(toEncryptString, AesKey, AesIV);
        }
     
        /// <summary>
        /// AES加密
        /// </summary>
        /// <param name="toEncryptString">待加密的明文</param>
        /// <returns></returns>
        public static string AesEncrypt(this string toEncryptString, string aesKey, string aesIV)
        {
            var rijndaelCipher = new RijndaelManaged
            {
                Mode = CipherMode.CBC,
                Padding = PaddingMode.PKCS7,
                KeySize = 128,
                BlockSize = 128
            };

            var toEncryptBytes = Encoding.UTF8.GetBytes(toEncryptString);
            var keyBytes = Encoding.UTF8.GetBytes(aesKey);
            var ivBytes = Encoding.UTF8.GetBytes(aesIV);

            rijndaelCipher.Key = keyBytes;
            rijndaelCipher.IV = ivBytes;

            ICryptoTransform transform = rijndaelCipher.CreateEncryptor();
            byte[] cipherBytes = transform.TransformFinalBlock(toEncryptBytes, 0, toEncryptBytes.Length);
            return Convert.ToBase64String(cipherBytes);
        }

        public static string AesDecrpt(string toDecrpt)
        {
            return AesDecrpt(toDecrpt, AesKey, AesIV);
        }
        /// <summary>
        /// AES解密
        /// </summary>
        /// <param name="toDecrpt"></param>
        /// <returns></returns>
        public static string AesDecrpt(this string toDecrpt, string aesKey, string aesIV)
        {
            var key = Encoding.UTF8.GetBytes(aesKey);
            var encryptedData = Convert.FromBase64String(toDecrpt);
            var iv = Encoding.UTF8.GetBytes(aesIV);

            var rDel = new RijndaelManaged
            {
                Key = key,
                IV = iv,
                Mode = CipherMode.CBC,
                Padding = PaddingMode.PKCS7
            };

            var cTransform = rDel.CreateDecryptor();
            var resultArray = cTransform.TransformFinalBlock(encryptedData, 0, encryptedData.Length);

            return Encoding.UTF8.GetString(resultArray);
        }

        public static string UrlEncode(string toEncryptString)
        {
            if (string.IsNullOrEmpty(toEncryptString)) return null;
            return HttpUtility.UrlEncode(AesEncrypt(toEncryptString), Encoding.UTF8);
        }

        public static string UrlDecode(string toEncryptString)
        {
            if (string.IsNullOrEmpty(toEncryptString)) return null;
            return AesDecrpt(toEncryptString);
        }

        public static string Decode(string toEncryptString)
        {
            if (string.IsNullOrEmpty(toEncryptString)) return null;
            return AesDecrpt(HttpUtility.UrlDecode(toEncryptString, Encoding.UTF8));
        }

        public static string GetMd5(this string source)
        {
            if (string.IsNullOrEmpty(source)) return null;

            MD5 md = MD5.Create();

            byte[] bytes = md.ComputeHash(System.Text.Encoding.UTF8.GetBytes(source));

            string dec = null;

            foreach (byte b in bytes)
            {

                dec += b.ToString("x2");

            }

            return dec;
        }
    }
}