using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Web;

namespace AUTS.Services.Tool
{
    public class IPHelper
    {
        public static string GetIP()
        {
            if (HttpContext.Current == null)
            {
                throw new Exception("HttpContext.Current为null");
            }

            string ip = string.Empty;
            if (!string.IsNullOrEmpty(HttpContext.Current.Request.ServerVariables["HTTP_VIA"]))
                ip = Convert.ToString(HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]);
            if (string.IsNullOrEmpty(ip))
                ip = Convert.ToString(HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"]);
            return ip;
        }

        /// <summary>获取客户端的IP，可以取到代理后的IP
        /// 
        /// </summary>
        /// <returns></returns>
        public static string GetClientIp()
        {
            string result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
            if (!string.IsNullOrEmpty(result))
            {
                //可能有代理  
                if (result.IndexOf(".", StringComparison.Ordinal) == -1)
                    result = null;
                else
                {
                    if (result.IndexOf(",", StringComparison.Ordinal) != -1)
                    {
                        //有“,”，估计多个代理。取第一个不是内网的IP。  
                        result = result.Replace("  ", "").Replace("'", "");
                        string[] temparyip = result.Split(",;".ToCharArray());
                        foreach (string t in temparyip)
                        {
                            if (IsIpAddress(t)
                                && t.Substring(0, 3) != "10."
                                && t.Substring(0, 7) != "192.168"
                                && t.Substring(0, 7) != "172.16.")
                            {
                                return t;        //找到不是内网的地址  
                            }
                        }
                    }
                    else if (IsIpAddress(result))  //代理即是IP格式  
                        return result;
                    else
                        result = null;        //代理中的内容  非IP，取IP  
                }
            }
            if (string.IsNullOrEmpty(result))
                result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
            if (string.IsNullOrEmpty(result))
                result = HttpContext.Current.Request.UserHostAddress;
            return result;
        }

        ///  <summary>判断是否是IP地址格式  0.0.0.0
        ///  
        ///  </summary>
        ///  <param  name="str">待判断的IP地址</param>
        ///  <returns>true  or  false</returns>
        public static bool IsIpAddress(string str)
        {
            if (string.IsNullOrEmpty(str) || str.Length < 7 || str.Length > 15) return false;

            const string regformat = @"^d{1,3}[.]d{1,3}[.]d{1,3}[.]d{1,3}$";

            Regex regex = new Regex(regformat, RegexOptions.IgnoreCase);
            return regex.IsMatch(str);
        }
    }
}