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

/// <summary>
/// 加密相關
/// </summary>
/// 

namespace MyWeb
{
    public class encrypt
    {
        public string MD5(string str, int bits = 32)   //MD5加密
        {
            if (bits == 16)
            {
                return FormsAuthentication.HashPasswordForStoringInConfigFile(str, "MD5").ToLower().Substring(8, 16);
            }
            else
            {
                return FormsAuthentication.HashPasswordForStoringInConfigFile(str, "MD5").ToLower();
            }
        }

        public string SHA1(string SourceStr)    //SHA1加密
        {
            return FormsAuthentication.HashPasswordForStoringInConfigFile(SourceStr, "SHA1");
        }

        private byte[] Keys = { 0xEF, 0xAB, 0x56, 0x78, 0x90, 0x34, 0xCD, 0x12 };

        public string EncryptDes(string SourceStr, string skey)       //使用標準DES對稱加密, skey請帶入8位數自訂KEY
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(skey.Substring(0, 8));
                byte[] rgbIV = Keys;
                byte[] inputByteArray = Encoding.UTF8.GetBytes(SourceStr);
                DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();
                MemoryStream mStream = new MemoryStream();
                CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                cStream.Write(inputByteArray, 0, inputByteArray.Length);
                cStream.FlushFinalBlock();
                string str = Convert.ToBase64String(mStream.ToArray());
                return str;
            }
            catch
            {
                return SourceStr;
            }
        }

        public string DecryptDes(string SourceStr, string skey)       //使用標準DES對稱解密, skey請帶入8位數自訂KEY
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(skey.Substring(0, 8));
                byte[] rgbIV = Keys;
                byte[] inputByteArray = Convert.FromBase64String(SourceStr);
                DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();
                MemoryStream mStream = new MemoryStream();
                CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                cStream.Write(inputByteArray, 0, inputByteArray.Length);
                cStream.FlushFinalBlock();
                return Encoding.UTF8.GetString(mStream.ToArray());
            }
            catch
            {
                return SourceStr;
            }
        }

        public string EncryptAutoKey(string str)
        {
            function f = new function();
            if (!f.isStrNull(str))
            {
                string key = f.randKey(8);
                string encode = EncryptDes(str, key);
                str = f.randKey(3) + f.Left(key, 5) + f.Left(encode, encode.Length - 2) + f.Right(key, 3) + f.Right(encode, 2);
                return str;
            }
            return "";
        }
        public string DecryptAutoKey(string str)
        {
            try
            {
                function f = new function();
                if (!string.IsNullOrEmpty(str))
                {
                    string str2 = str?.Substring(3, (str ?? "").Length - 3);
                    string key = f.Left(str2, 5) + f.Left(f.Right(str2, 5), 3);
                    str2 = str2.Substring(5, str2.Length - 10) + f.Right(str2, 2);
                    return DecryptDes(str2, key);
                }
                    
            }
            catch (Exception ex)
            {

            }
            return str;
        }


        public string SHA256(string str)
        {
            using (SHA256 hash = SHA256Managed.Create())
            {
                return string.Concat(hash
                  .ComputeHash(Encoding.UTF8.GetBytes(str))
                  .Select(item => item.ToString("x2")));
            }
        }

        public string followerHash(string s1, string s2)
        {
            string input = s1 + s2;
            input = new string(input.Where(c => 
                char.IsLetterOrDigit(c)).ToArray()).ToUpper();
            return SHA256(input);
        }
    }
}