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

namespace CB.Common
{
    public class BlackIpHttpModule : IHttpModule
    {
        public void Dispose() { }

        public void Init(HttpApplication application)
        {
            application.BeginRequest += new EventHandler(Application_BeginRequest);
        }

        private void Application_BeginRequest(object sender, EventArgs e)
        {
            HttpApplication application = (HttpApplication)sender;
            //using (var sw = new StreamWriter(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "ipaddress.txt"), true, System.Text.Encoding.Default))
            //{
            //    sw.WriteLine("Ip => " + IPAddress);
            //    sw.Flush();
            //}
            if (BlackIPs.Any(ip => ip == IPAddress))
            {
                application.Context.Response.Write("禁止访问");
                application.Context.Response.StatusCode = (int)System.Net.HttpStatusCode.Forbidden;
                application.CompleteRequest();
            }
        }

        public static string IPAddress
        {
            get
            {
                string userIP;
                // HttpRequest Request = HttpContext.Current.Request;  
                HttpRequest Request = HttpContext.Current.Request; // ForumContext.Current.Context.Request;  
                // 如果使用代理，获取真实IP  
                if (Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != "")
                    userIP = Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
                else
                    userIP = Request.ServerVariables["REMOTE_ADDR"];
                if (userIP == null || userIP == "")
                    userIP = Request.UserHostAddress;
                return userIP;
            }
        }

        private volatile static List<string> _blacklist = null;
        public List<string> BlackIPs
        {
            get
            {
                if (_blacklist == null)
                {
                    _blacklist = new List<string>();
                    string s = System.Configuration.ConfigurationManager.AppSettings["blackips"];
                    if (!string.IsNullOrEmpty(s))
                    {
                        _blacklist.AddRange(s.Trim().Split(new char[] { ';' }, StringSplitOptions.RemoveEmptyEntries));
                    }
                }
                return _blacklist;
            }
        }
    }
}