//引入命名空间
using System;
using System.Configuration;
using System.Web.Configuration;
using System.Web;
using System.Web.SessionState;

namespace Samples.AspNet.Session
{

  public class MySessionIDManager : IHttpModule, ISessionIDManager
  {

    private SessionStateSection pConfig = null;

    //
    // IHttpModule Members
    //

    //
    // IHttpModule.Init
    //

    public void Init(HttpApplication app)
    {
      // Obtain session-state configuration settings.

      if (pConfig == null)
      {
        Configuration cfg =
          WebConfigurationManager.OpenWebConfiguration(System.Web.Hosting.HostingEnvironment.ApplicationVirtualPath);
        pConfig = (SessionStateSection)cfg.GetSection("system.web/sessionState");
      }
    }

    //
    // IHttpModule.Dispose
    //

    public void Dispose()
    {
    }

    //
    // ISessionIDManager Members
    //

    //
    // ISessionIDManager.Initialize
    //

    public void Initialize()
    {
    }

    //
    // ISessionIDManager.InitializeRequest
    //

    public bool InitializeRequest(HttpContext context, 
                                  bool suppressAutoDetectRedirect, 
                                  out bool supportSessionIDReissue)
    {
      if (pConfig.Cookieless == HttpCookieMode.UseCookies)
      {
        supportSessionIDReissue = false;
        return false;
      }
      else
      {
        supportSessionIDReissue = true;
        return context.Response.IsRequestBeingRedirected;
      }
    }

    //
    // ISessionIDManager.GetSessionID
    //
    public string GetSessionID(HttpContext context)
    {
      string id = null;

      if (pConfig.Cookieless == HttpCookieMode.UseUri)
      {
        // Retrieve the SessionID from the URI.
      }
      else
      {
        id = context.Request.Cookies[pConfig.CookieName].Value;
      }      

      // Verify that the retrieved SessionID is valid. If not, return null.

      if (!Validate(id))
        id = null;

      return id;
    }

    //
    // ISessionIDManager.CreateSessionID
    //

    public string CreateSessionID(HttpContext context)
    {
      return Guid.NewGuid().ToString();
    }

    //
    // ISessionIDManager.RemoveSessionID
    //

    public void RemoveSessionID(HttpContext context)
    {
      context.Response.Cookies.Remove(pConfig.CookieName);
    }

    //
    // ISessionIDManager.SaveSessionID
    //

    public void SaveSessionID(HttpContext context, string id, out bool redirected, out bool cookieAdded)
    {
      redirected = false;
      cookieAdded = false;

      if (pConfig.Cookieless == HttpCookieMode.UseUri)
      {
        // Add the SessionID to the URI. Set the redirected variable as appropriate.

        redirected = true;
        return;
      }
      else
      {
        context.Response.Cookies.Add(new HttpCookie(pConfig.CookieName, id));
        cookieAdded = true;
      }
    }

    //
    // ISessionIDManager.Validate
    //

    public bool Validate(string id)
    {
      try
      {
        Guid testGuid = new Guid(id);

        if (id == testGuid.ToString())
          return true;
      }
      catch
      {
      }

      return false;
    }
  }
}