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);
        }

        /// <summary>
        /// 生成 search_keywords 的 HEX 編碼字串
        /// </summary>
        /// <param name="follower">follower 物件</param>
        /// <returns>HEX 編碼字串</returns>
        public string GenerateSearchKeywords(Model.follower follower)
        {
            try
            {
                // 解密各欄位
                string phone_decrypted = string.IsNullOrEmpty(follower.phone) ? "" : DecryptAutoKey(follower.phone);
                string cellphone_decrypted = string.IsNullOrEmpty(follower.cellphone) ? "" : DecryptAutoKey(follower.cellphone);
                string id_code_decrypted = string.IsNullOrEmpty(follower.id_code) ? "" : DecryptAutoKey(follower.id_code);
                string passport_decrypted = string.IsNullOrEmpty(follower.passport) ? "" : DecryptAutoKey(follower.passport);

                // 組合字串 (使用 | 分隔)
                string joinedString = string.Join("|", new string[] {
                    phone_decrypted,
                    cellphone_decrypted,
                    id_code_decrypted,
                    passport_decrypted
                });

                // 轉換為 HEX 編碼
                if (string.IsNullOrEmpty(joinedString.Replace("|", "")))
                {
                    return ""; // 如果所有欄位都是空的，返回空字串
                }

                byte[] bytes = Encoding.UTF8.GetBytes(joinedString);
                string hexString = BitConverter.ToString(bytes).Replace("-", "").ToLower();
                return hexString;
            }
            catch
            {
                return ""; // 發生錯誤時返回空字串
            }
        }

        /// <summary>
        /// 將搜尋字串轉換為 HEX 編碼 (用於搜尋功能)
        /// </summary>
        /// <param name="searchText">要搜尋的文字</param>
        /// <returns>HEX 編碼字串</returns>
        public string ConvertToHex(string searchText)
        {
            try
            {
                if (string.IsNullOrEmpty(searchText))
                    return "";

                byte[] bytes = Encoding.UTF8.GetBytes(searchText);
                string hexString = BitConverter.ToString(bytes).Replace("-", "").ToLower();
                return hexString;
            }
            catch
            {
                return "";
            }
        }
    }
}