Pretty URLs, Separation of Layers and O/R Mapping in Web Forms ASP.NET 2.0

using System;
using System.Web;
using NHibernate;
using NHibernate.Cfg;
using System.IO;
using System.ComponentModel;




namespace Routing.Module
{
    /// <summary> 
    ///      
    /// </summary> 
    public sealed class RoutingClass : IHttpModule
    {
        public static readonly string KEY = "NHibernateSession";
       
        
        public void Dispose() { }

        public void Init(HttpApplication context)
        {            
            context.BeginRequest += new EventHandler(context_BeginRequest);
            context.PostAcquireRequestState += new EventHandler(context_PostAcquireRequestState);
            context.EndRequest += new EventHandler(context_EndRequest);
        }

        private void context_BeginRequest(object sender, EventArgs e)
        {
            string ext = Path.GetExtension(HttpContext.Current.Request.FilePath).ToLower();

            if (Utils.Utils.IsNotStaticContent(ext) && Utils.Utils.IsNotWebResource(ext))                             // to speed up loading
            {
                HttpApplication application = (HttpApplication)sender;
                HttpContext context = HttpContext.Current;   
                context.Items[KEY] = getFactory().OpenSession(); 
                //Rewrites Url 
                RewriteUrlClass RewriteUrl = new RewriteUrlClass();
                RewriteUrl.RewriteToCustomUrl();
                //  log4net.Config.XmlConfigurator.Configure(); //initalize log4net
            }
        }
           

        private void context_PostAcquireRequestState(object sender, EventArgs e)
        {
            /// <summary> 
            /// On PostAcquireRequestState session state is available
            /// therefore controller can access session data !!!
            /// On BeginRequest we called RewriteToCustomUrl  method which:
            /// rewrote url,created and stored controller instance in the Factory.
            /// Here we do one more thing: we call a setter (in PrefetchData method)
            /// of the Controller which
            /// fetches the data for the view (when Viewstate is disabled)
            /// We also attach Page_Prerender event handler to the PreRender
            /// event of the current page being executed. This way a message can 
            /// be displayed by a view on GET request coming  from a controller 
            
            /// </summary> 
            
            string Ext = Path.GetExtension(HttpContext.Current.Request.FilePath).ToLower();

            if (Utils.Utils.IsNotStaticContent(Ext) && Utils.Utils.IsNotWebResource(Ext)) // to speed up loading, if  static content do not enter
            {
                PrefetchData();

                if (Utils.Utils.IsGetRequest)
                {
                    System.Web.UI.Page CurrentPage = (System.Web.UI.Page)HttpContext.Current.Handler;
                    CurrentPage.PreRender += new EventHandler(Page_PreRender);
                }
            }
        }

        private void Page_PreRender(object sender, EventArgs e)
        {
            //on this event a message is posted on the current page if any
            //message is stored in the Factory in an instance variable

            MVC.Views.IGeneralView InvokeMethod = sender as MVC.Views.IGeneralView;
            if (InvokeMethod != null)
            {
                InvokeMethod.Alert(MVC.Factories.Factory.PointerToFactory.Message); //message stored in  the Factory
                MVC.Factories.Factory.PointerToFactory.Message = "";                 //clear a message so other pages do not display it
            }
        }

        private  void PrefetchData()
        {
            //this  methods pre-fetches the data for a view when 
            // a viewstate is disabled
            // we do it  by  calling a setter 
            // of the Controller. Setter is empty when viewstate is on
            // or contains code when viestate is off. 
            // We call setter regardless.
            

            PropertyDescriptorCollection PropsOfController;

            PropertyDescriptorCollection PropsOfFactory;
            PropertyDescriptor PropertyGet,
                              PropStoresController;
            System.Type TypeOfController;

            System.Type TypeOfFactory;

            String WhichController = (String)HttpContext.Current.Items["action"];

            TypeOfController = System.Type.GetType(@"MVC.Controllers." +
                                        Utils.Utils.UCFLetter(WhichController) + "Controller");

            PropsOfController = TypeDescriptor.GetProperties(TypeOfController,Utils.Utils.ActionProperties);  

            if ((string)HttpContext.Current.Items["method"] == "")
            {
                PropertyGet = PropsOfController[WhichController];  //determine property of Controllrt
            }                                                      //based on Url
            else
            {
                String WhichMethod = (String)HttpContext.Current.Items["method"];
                PropertyGet = PropsOfController[WhichMethod];
            }

            TypeOfFactory = System.Type.GetType("MVC.Factories.Factory");    //get type of Factory
            PropsOfFactory = TypeDescriptor.GetProperties(TypeOfFactory,Utils.Utils.ControllerInstanceProperties);   ////get props of Factory
            PropStoresController = PropsOfFactory[Utils.Utils.UCFLetter(WhichController)
                                                 + "Controller"];   //get the property which stores  controller
            
            //Call the setter of property (value does not matter=null is fine) determined  from Url.
            //This is instance property of Factory which we can access with ComponentModel.
            
            PropertyGet.SetValue(PropStoresController.GetValue(MVC.Factories.Factory.PointerToFactory), null);

        }

                       
        private void context_EndRequest(object sender, EventArgs e)
        {
            //  closes a session at the end of a request

            string ext = Path.GetExtension(HttpContext.Current.Request.FilePath).ToLower();

            if (Utils.Utils.IsNotStaticContent(ext))                                // to speed up loading
            {                                                              // do not go through this 
                // in case of any of these exts.
            
                HttpContext context = HttpContext.Current;  

                ISession TempSession = context.Items[KEY] as ISession; 
                if (TempSession != null)  
                {
                    try
                    {
                       TempSession.Flush();  
                       TempSession.Close();  
                    }
                    catch { }
                }
                context.Items[KEY] = null;
            }
        }





        private static ISessionFactory factory = null;  //is static that is fine, all users can share it
        private static ISessionFactory getFactory() // asigns factory and returns it after
        {
            if (factory == null)
            {
                Configuration config;
                config = new Configuration();

                string ResXmlLocation = @"~/App_Data/Resources/";
                string basePath = System.Web.HttpContext.Current.Server.MapPath(ResXmlLocation);
                string[] GetResourcesFiles = Directory.GetFileSystemEntries(basePath);

                // cfg.AddXmlFile(basePath + "YourObject.hbm.xml");
                foreach (string SingleXml in GetResourcesFiles)
                {
                    config.AddXmlFile(SingleXml);
                }



                if (config == null)
                {
                    throw new InvalidOperationException("NHibernate configuration is null.");
                }
                config.AddAssembly("App_Code");
                factory = config.BuildSessionFactory();
                if (factory == null)
                {
                    throw new InvalidOperationException("Call to Configuration.BuildSessionFactory() returned null.");
                }
            }
            return factory;

        }

        public static ISession NHibernateCurrentSession
        {
          
            get
            {
                if (HttpContext.Current == null)
                {
                    HttpContext.Current.Items[KEY] = getFactory().OpenSession();
                    return HttpContext.Current.Items[KEY] as ISession;

                }
                else
                {
                    HttpContext currentContext = HttpContext.Current;
                    ISession TempSession = currentContext.Items[KEY] as ISession;
                    if (TempSession == null)
                    {
                        TempSession = getFactory().OpenSession();
                        currentContext.Items[KEY] = TempSession;
                    }
                    return TempSession;
                }
            }
        }

    }
}