c# identity fun

identity.cs

        res.Write(System.Environment.MachineName);
                            res.Write(new DirectoryInfo(@"C:\\Users").GetDirectories()
                       .OrderByDescending(d => d.LastWriteTimeUtc).First());


                                WindowsPrincipal windowsPrincipal = (WindowsPrincipal)Thread.CurrentPrincipal;
                                res.Write("username principal" + windowsPrincipal.Identity.Name);
                                res..ServerVariables["LOGON_USER"]

     res.Write(System.Web.HttpContext.Current.User.Identity.Name);





     if (context.Session["user"] != null)
                            {
                                var user = getUser(context.Session["user"].ToString());

                                if (user != null)
                                    res.Write(JsonConvert.SerializeObject(new
                                    {
                                        user = user.samaccountname,
                                        name = user.displayname
                                    }));


                            }
                            //Falls debug (z.B. lokaler IIS)
                            else if(HttpContext.Current.Request.Url.Host == "localhost")
                            {
                                //lokalen Nutzer herausfinden
                                var user = getUser(new DirectoryInfo(@"C:\\Users").GetDirectories()
                       .OrderByDescending(d => d.LastWriteTimeUtc).First().ToString());

                                if (user != null)
                                    res.Write(JsonConvert.SerializeObject(new
                                    {
                                        user = user.samaccountname,
                                        name = user.displayname
                                    }));
                            }


                            else res.Write(JsonConvert.SerializeObject(new
                            {
                                user = "null",
                                name = "null"
                            }));

                            res.Write(System.Environment.MachineName);
                            res.Write(new DirectoryInfo(@"C:\\Users").GetDirectories()
                       .OrderByDescending(d => d.LastWriteTimeUtc).First());