#region

using System;
using System.Text;
using CSFrameworkV5.Common;
using CSFrameworkV5.Core;

#endregion

namespace CSFrameworkV5.WCFContract
{
    /// <summary>
    ///     WebService接口安全管理核心类
    /// </summary>
    public class WebServiceSecurity
    {
        private const int WCF_PREFIX_LEN = 16; /*预设伪造16位的数据(校验码)*/
        private const int WCF_SUFFIX_LEN = 8; /*预设伪造8位的数据(校验码)*/

        /// <summary>
        ///     加密用户登录凭证
        /// </summary>
        /// <param name="user">当前用户登录信息</param>
        /// <returns></returns>
        public static byte[] EncryptLoginer(Loginer user)
        {
            var user_byte = ZipTools.CompressionObject(user);
            var result =
                new byte[user_byte.Length + WCF_PREFIX_LEN + WCF_SUFFIX_LEN];

            var prefix = GetByteData(WCF_PREFIX_LEN);
            var suffix = GetByteData(WCF_SUFFIX_LEN);

            Array.Copy(user_byte, 0, result, WCF_PREFIX_LEN,
                user_byte.Length); //复制用户数据
            Array.Copy(prefix, 0, result, 0, prefix.Length); //复制头部伪码
            Array.Copy(suffix, 0, result, result.Length - WCF_SUFFIX_LEN,
                suffix.Length); //复制尾部伪码

            return result;
        }

        /// <summary>
        ///     用户登录信息加密后伪造指定位数的数据.
        /// </summary>
        private static byte[] GetByteData(int bit)
        {
            //128位伪造数据
            var chars = "ZA1D30A4B5C006S3LDFGHKD72C8E920D" +
                        "FJKQ30F506E7EQWERUIYUI02F1A0D0IO" +
                        "WEURTK236890L23B3B40C5E180D6F4D5" +
                        "EOPFDGHKW3IT6F4X90238503AS1094A2";

            if (bit < 2) bit = 2; //最少两位

            var n = GetRandomNum(chars.Length - bit - 2); //获取随机数
            var s = chars.Substring(n - 1, bit);
            var result = Encoding.ASCII.GetBytes(s);
            return result;
        }

        /// <summary>
        ///     自定义用户登录验证码
        /// </summary>
        /// <returns></returns>
        public static byte[] GetLoginTicket()
        {
            var result = Encoding.ASCII.GetBytes(Globals.WCF_LOGIN_TICKET);
            return result;
        }

        //获取随机数
        private static int GetRandomNum(int maxValue)
        {
            var seed = new Random();
            var randomNum = new Random();
            return randomNum.Next(1, maxValue);
        }

        /// <summary>
        ///     检查用户登录凭证，验证通过才允许访问后台数据.
        /// </summary>
        /// <param name="loginer">用户登录凭证</param>
        /// <returns></returns>
        public static Loginer ValidateLoginer(byte[] loginer)
        {
            //用户登录信息的长度小于伪码长度,数据包无效!
            if (loginer.Length < WCF_PREFIX_LEN + WCF_SUFFIX_LEN) //return null;
                throw new Exception("验证用户资料失败!");

            try
            {
                //用户登录信息的长度
                var objectArrar = new byte[loginer.Length -
                                           (WCF_PREFIX_LEN + WCF_SUFFIX_LEN)];

                //复制用户登录信息的数据包(去掉前后伪码)
                Array.Copy(loginer, WCF_PREFIX_LEN, objectArrar, 0,
                    objectArrar.Length);

                //转换为用户对象
                var user = (Loginer)ZipTools.DecompressionObject(objectArrar);

                if (user.Account.Length >= 1) //系统限制用户帐号的长度必须大于或等于1位
                    return user; //转换成功,返回用户对象.                

                throw new Exception("用户帐号不正确!");
            }
            catch
            {
                throw new Exception("验证用户资料失败!");
            }
        }

        /// <summary>
        ///     用户登录的验证码,防止用户恶意攻击Login接口.
        /// </summary>
        /// <param name="ticket">验证码</param>
        /// <returns></returns>
        public static bool ValidateLoginIdentity(byte[] validationTicket)
        {
            if (validationTicket == null ||
                validationTicket.Length < Encoding.ASCII
                    .GetBytes(Globals.WCF_LOGIN_TICKET).Length)
                throw new Exception("验证用户资料失败!");

            //取系统定义的验证码,你可以定义为128位.
            var TicketString =
                Encoding.ASCII.GetString(GetLoginTicket()).ToUpper();

            //客户端传来的验证码与系统定义的相比较
            var success =
                Encoding.ASCII.GetString(validationTicket).ToUpper() ==
                TicketString;

            if (success == false)
                throw new Exception("无效的验证码! 你还可以尝试X次,否则查你户口,封你IP!");

            return success;

            //
            //设计一个防止用户恶意攻击的管理器,记录每次调用的方法名及调用时间,
            //如果在指定的时间内调用超过最大限制数则视为恶意攻击,你可以暂时封杀
            //用户的IP.
            //
        }
    }
}