using System;
using System.Collections.Generic;
using System.DirectoryServices;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace Eugen.ESystem
{
    public class User
    {
        #region Version und Copyright
        // Version und Copyright
        static string dllName = Path.GetFileNameWithoutExtension(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase); //Den Programmnamen auslesen
        static string dllVersion = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version.ToString();
        static object[] attributes = Assembly.GetExecutingAssembly().GetCustomAttributes(typeof(AssemblyCopyrightAttribute), false);
        static string copyright = GenerateCopyright();

        //Assembly Datum und Zeit
        static DateTime value = AssemblyDateTime();
        static string date = value.ToShortDateString();
        static 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 DLL-Info
        /// <summary>
        /// Contains the name of the dll file.
        /// </summary>
        public static string DllName { private set; get; }

        /// <summary>
        /// Contains the version of the dll file.
        /// </summary>
        public static string DllVersion { private set; get; }

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

        /// <summary>
        /// Contains the name-, version- and copyright-information of the dll file.
        /// </summary>
        public static string[] DllInfo { private set; get; }

        private static void SetDllInfo()
        {
            //Name, Version und Copyright setzen
            DllName = dllName;
            DllVersion = dllVersion;
            Copyright = copyright;

            string[] dllInfo = new string[3];
            dllInfo[0] = dllName;
            dllInfo[1] = dllVersion;
            dllInfo[2] = copyright;
            DllInfo = dllInfo;
        }

        protected string ProgramName { private set; get; }
        protected string ProgramVersion { private set; get; }
        protected string ProgramCopyright { private set; get; }
        #endregion

        static User()
        {
            SetDllInfo();
        }

        /// <summary>
        /// Current User
        /// </summary>
        /// <returns>Returns the current user</returns>
        public static string Current()
        {
            return Environment.UserName;
        }

        /// <summary>
        /// Domain of the current user
        /// </summary>
        /// <returns>Returns the domain of the current user</returns>
        public static string Domain()
        {
            return CurrentDomainUser().Remove(CurrentDomainUser().IndexOf("\\"));
        }

        /// <summary>
        /// Is the user a 'cadm'
        /// </summary>
        /// <returns>If the user is a 'cadm' true is returned, otherwise false</returns>
        public static bool IsCadm()
        {
            if (UserExists(String.Concat(Current(), ".cadm"), User.Domain(), null, null, null))
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        /// <summary>
        /// Is the user a 'adm'
        /// </summary>
        /// <returns>If the user is a 'adm' true is returned, otherwise false</returns>
        public static bool IsAdm()
        {
            if (UserExists(String.Concat(Current(), ".adm"), User.Domain(), null, null, null))
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        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;
            }
        }

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