Refresh Module

using System;
using System.IO;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;

namespace RefreshModule
{
    internal class RefreshManager
    {   
        private class ClientInfo
        {
            public string PageID;
            public int Ticket;
            public int Hash;
            public ClientInfo(string pageID, int ticket, int hash)
            {
                PageID = pageID;
                Ticket = ticket;
                Hash = hash;
            }
        }
            
        private const string INFO_ON_CLIENT_SIDE = "_iocs_";
        private const string TICKET_MANAGER_ID = "_tmi_";
        private const string REFRESH_ENTRY = "_re_";
        public const string HIDDENFIELD_TEMPLATE = "[{0}]:[{1}]";
        private HttpContext context = null;

        public RefreshManager():this(HttpContext.Current)
        {
            
        }
        
        public RefreshManager(HttpContext context)
        {
            this.context = context;
            InitializeClientData();
        }
        
        private void InitializeClientData()
        {
            if (context.Items[INFO_ON_CLIENT_SIDE] == null)
            {
                TextReader read = new StreamReader(context.Request.InputStream);
                string input = read.ReadToEnd();
                try
                {
                    string[] ci = context.Request[INFO_ON_CLIENT_SIDE].Split(":".ToCharArray());
                    
                    Guid pageID = new Guid(ci[0].Trim("[]".ToCharArray()));
                    int ticket = Int32.Parse(ci[1].Trim("[]".ToCharArray()));
                    context.Items[INFO_ON_CLIENT_SIDE] =
                        new ClientInfo(pageID.ToString(),ticket, input.GetHashCode());
                }
                catch
                {

                    context.Items[INFO_ON_CLIENT_SIDE] =
                        new ClientInfo(Guid.NewGuid().ToString(), 0, input.GetHashCode());
                }
            }
        }
        
        public string PageID
        {
            get
            {
                return (context.Items[INFO_ON_CLIENT_SIDE] as ClientInfo).PageID;
            }
        }

        public int ClientTicket
        {   
            get
            {
                return (context.Items[INFO_ON_CLIENT_SIDE] as ClientInfo).Ticket;
            }
        }


        public int CurrentHash
        {
            get
            {
                return (context.Items[INFO_ON_CLIENT_SIDE] as ClientInfo).Hash;
            }
        }
        
        public static bool IsPageRefreshed
        {
            get
            {
                if(HttpContext.Current.Items[REFRESH_ENTRY] == null)
                    return false;
                return (bool) HttpContext.Current.Items[REFRESH_ENTRY]; 
            }
            
            internal set
            {
                HttpContext.Current.Items[REFRESH_ENTRY] = value; 
            }
        }
        
        public void RegisterHidenFields(Page page)
        {
            TicketManager manager = Manager;
            if (!manager.IsPageRegistred(PageID))
            {
                manager.RegisterKey(PageID, CurrentHash);
            }
            page.ClientScript.RegisterHiddenField(INFO_ON_CLIENT_SIDE,
                string.Format(HIDDENFIELD_TEMPLATE, PageID, manager.GetNextTicket(PageID, IsPageRefreshed)));
        }
       
      

        public TicketManager Manager
        {
            get
            {
                 HttpSessionState session = HttpContext.Current.Session;
                 if (session[TICKET_MANAGER_ID] == null)
                    session[TICKET_MANAGER_ID] = new TicketManager();
                
                 return session[TICKET_MANAGER_ID] as TicketManager;
            }
        }
      
        public bool CheckRequest()
        {
            TicketManager manager = Manager;
            
            if(!manager.IsPageRegistred(PageID))
            {
                manager.RegisterKey(PageID, CurrentHash);
            }

            IsPageRefreshed = manager.IsTicketCashed(
                PageID, ClientTicket, CurrentHash);
            
            if(!IsPageRefreshed)
                manager.UpdateTicket(PageID, ClientTicket, CurrentHash);
            
            return IsPageRefreshed;
        }
   }
}