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

namespace Do.NET.Web
{
    //web.config  <system.web> <sessionState mode="InProc" cookieless="UseUri" timeout="30"/>
    //Do.NET.Web.CurrentUserModule.Count gibt die Anzahl der Benutzer im System
    /*
    <httpModules>
      <add name="CurrentUserModule" type="Do.NET.Web.CurrentUserModule, Do.NET.Web"/>
    </httpModules>
    */
    public class CurrentUserModule : IHttpModule
    {
        #region Props
        static TimeSpan _deleteSpan = new TimeSpan(0, 5, 0);//5 min
        static Hashtable _sessions = new Hashtable(10000);       
        #endregion

        public static int Count
        {
            get
            {
                int counter = 0;
                //HttpContext context = HttpContext.Current;
                try
                {
                    lock(_sessions)
                    {
                    //CurrentUserModule mod = context.ApplicationInstance.Modules.Get("CurrentUserModule") as CurrentUserModule;
                    counter = _sessions.Count;
                    }
                }
                catch (Exception ex)
                {
                    throw new NotSupportedException("Module name CurrentUserModule not found", ex);
                }
                return counter;
            }
        }

        #region IHttpModule Members
        public void Dispose()
        {
            _sessions.Clear();
        }

        public void Init(HttpApplication context)
        {
            context.AcquireRequestState += new EventHandler(context_AcquireRequestState);
        }
        #endregion

        void context_AcquireRequestState(object sender, EventArgs e)
        {
            lock (_sessions)
            {
                if (HttpContext.Current.Session == null)
                    return;

                string key = HttpContext.Current.Session.SessionID;
                if (_sessions.ContainsKey(key))
                {
                    _sessions[key] = DateTime.Now.Add(_deleteSpan);
                }
                else
                {//new User
                    //Delete user by deleteSpan
                    if (_sessions.Count > 0)
                    {
                        try
                        {
                            foreach (string tmp_key in _sessions.Keys)
                            {
                                DateTime? time = _sessions[tmp_key] as DateTime?;
                                if (time.HasValue)
                                {
                                    if (time.Value < DateTime.Now)
                                    {
                                        _sessions.Remove(tmp_key);
                                    }
                                }
                            }
                        }
                        catch (Exception ex)
                        {
                            System.Diagnostics.Debug.Write(ex.ToString());
                        }
                    }
                    _sessions[key] = DateTime.Now.Add(_deleteSpan);
                }
            }
        }

    }
}