using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.DirectoryServices;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Security;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Test_Benutzername
{
    public partial class Form1 : Form
    {
        #region Version und Copyright
        // Version und Copyright
        string programName = Path.GetFileNameWithoutExtension(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase); //Den Programmnamen auslesen
        string programVersion = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version.ToString();
        static object[] attributes = Assembly.GetExecutingAssembly().GetCustomAttributes(typeof(AssemblyCopyrightAttribute), false);
        string copyright = GenerateCopyright();
        string icon = Application.StartupPath + "\\Info.bmp";

        //Assembly Datum und Zeit
        static DateTime value = AssemblyDateTime();
        string date = value.ToShortDateString();
        string time = value.ToLongTimeString();

        private static DateTime AssemblyDateTime()
        {
            var version = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version;
            var buildDateTime = new DateTime(2000, 1, 1).Add(new TimeSpan(TimeSpan.TicksPerDay * version.Build + TimeSpan.TicksPerSecond * 2 * version.Revision));
            //Tage seit dem 1. Januar 2000 und Sekunden seit Mitternacht, (multiplizier mit 2 ergibt das Original)
            return buildDateTime;
        }

        private static string CurrentYear()
        {
            DateTime dtn = DateTime.Now;
            return dtn.Year.ToString();
        }

        private static string StartYear()
        {
            string startYear = "";
            if (((AssemblyCopyrightAttribute)attributes[0]).Copyright.Contains("Copyright © "))
            {
                startYear = ((AssemblyCopyrightAttribute)attributes[0]).Copyright.Replace("Copyright © ", "");
                while (startYear.StartsWith(" "))
                {
                    startYear = startYear.Remove(0, 1);
                }

                if (startYear.Contains("-"))
                {
                    startYear = startYear.Remove(startYear.IndexOf("-"));
                }
                else
                {
                    startYear = startYear.Remove(startYear.IndexOf(" "));
                }
                return startYear;
            }
            else
            {
                DateTime dtn = DateTime.Now;
                return dtn.Year.ToString();
            }
        }

        private static string GenerateCopyright()
        {
            string startYear = StartYear();
            string currentYear = CurrentYear();

            if (startYear == currentYear)
            {
                return ((AssemblyCopyrightAttribute)attributes[0]).Copyright;
            }
            else
            {
                string temp = ((AssemblyCopyrightAttribute)attributes[0]).Copyright;
                string start = temp.Remove(temp.IndexOf(startYear) - 1);
                string end = (temp.Remove(0, temp.IndexOf(" by")));

                return String.Concat(start, " ", startYear, "-", currentYear, end);
            }
        }
        #endregion

        #region Programm-Info
        /// <summary>
        /// Contains the name of the program file
        /// </summary>
        public static string ProgramName { set; get; }

        /// <summary>
        /// Contains the version of the program file
        /// </summary>
        public static string ProgramVersion { set; get; }

        /// <summary>
        /// Contains the copyright notice
        /// </summary>
        public static string Copyright { set; get; }

        private void SetProgramInfo()
        {
            //Name, Version und Copyright setzen
            ProgramName = programName;
            ProgramVersion = programVersion;
            Copyright = copyright;
        }
        #endregion
        public Form1()
        {
            SetProgramInfo();
            InitializeComponent();
        }

        //public static Boolean CheckNTLogon(String Username, String password)
        //{
        //    IntPtr _token;
        //    UnsafeNativeMethods.LogonUserEx(Username, Environment.UserDomainName, password,
        //       SafeNativeMethods.UnsafeNativeMethods.LogonType.Logon32_Interactive,
        //       0, out _token, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);
        //    UnsafeNativeMethods.CloseHandle(_token);
        //    return _token != IntPtr.Zero;
        //}

        private void buttonStart_Click(object sender, EventArgs e)
        {
            labelResult.Text = "Aktueller User: " + CurrentUser();
            labelResult.Text += Environment.NewLine + "Aktueller Domain/Username: " + CurrentDomainUser();

            string user = String.Concat(CurrentUser(), ".cadm");
            string domain = CurrentDomainUser().Remove(CurrentDomainUser().IndexOf("\\"));

            if (UserExists(user, domain, null, null, null))
            {
                labelResult.Text += Environment.NewLine + "Gefundener Username: " + user;
            }
            else
            {
                labelResult.Text += Environment.NewLine + "User " + user + " wurde nicht gefunden";
            }
        }

        private string CurrentUser()
        {
            return Environment.UserName;
        }

        private string CurrentDomainUser()
        {
            return System.Security.Principal.WindowsIdentity.GetCurrent().Name;
        }

        private static bool UserExists (string userName, string domainName, string machineName, string authenticationUser, string authenticationPassword)
        {
            if (domainName == null && machineName == null)
            {
                machineName = Environment.MachineName;
            }

            string adsiPath = "WinNT://";
            if (domainName != null && machineName != null)
            {
                adsiPath += domainName + "/" + machineName + ",computer";
            }
            else if (machineName != null)
            {
                adsiPath += machineName + ",computer";
            }
            else if (domainName != null)
            {
                adsiPath += domainName + ",domain";
            }
            DirectoryEntry computerEntry = new DirectoryEntry(adsiPath, authenticationUser, authenticationPassword);

            try
            {
                DirectoryEntry userEntry = computerEntry.Children.Find(userName, "user");
                return true;
            }
            catch
            {
                return false;
            }
        }
    }
}