using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using Server.Accounting;
using Server.Network;

namespace Server.Misc
{
  public class CrashGuard
  {
    private static bool Enabled = true;
    private static bool SaveBackup = true;
    private static bool RestartServer = true;
    private static bool GenerateReport = true;

    public static void Initialize()
    {
      if (Enabled) // If enabled, register our crash event handler
        EventSink.Crashed += CrashGuard_OnCrash;
    }

    public static void CrashGuard_OnCrash(CrashedEventArgs e)
    {
      if (GenerateReport)
        GenerateCrashReport(e);

      World.WaitForWriteCompletion();

      if (SaveBackup)
        Backup();


      /*if ( Core.Service )
        e.Close = true;
      else */
      if (RestartServer)
        Restart(e);
    }

    private static void SendEmail(string filePath)
    {
      Console.Write("Crash: Sending email...");

      if (Email.FROM_ADDRESS != null && Email.CRASH_ADDRESS != null)
        Email.SendCrashEmail(filePath);

    }

    private static string GetRoot()
    {
      try
      {
        return Path.GetDirectoryName(Environment.GetCommandLineArgs()[0]);
      }
      catch
      {
        return "";
      }
    }

    private static string Combine(string path1, string path2) => path1.Length == 0 ? path2 : Path.Combine(path1, path2);

    private static void Restart(CrashedEventArgs e)
    {
      string root = GetRoot();

      Console.Write("Crash: Restarting...");

      try
      {
        Process.Start(Core.ExePath, Core.Arguments);
        Console.WriteLine("done");

        e.Close = true;
      }
      catch
      {
        Console.WriteLine("failed");
      }
    }

    private static void CreateDirectory(string path)
    {
      if (!Directory.Exists(path))
        Directory.CreateDirectory(path);
    }

    private static void CreateDirectory(string path1, string path2)
    {
      CreateDirectory(Combine(path1, path2));
    }

    private static void CopyFile(string rootOrigin, string rootBackup, string path)
    {
      string originPath = Combine(rootOrigin, path);
      string backupPath = Combine(rootBackup, path);

      try
      {
        if (File.Exists(originPath))
          File.Copy(originPath, backupPath);
      }
      catch
      {
        // ignored
      }
    }

    private static void Backup()
    {
      Console.Write("Crash: Backing up...");

      try
      {
        string timeStamp = GetTimeStamp();

        string root = GetRoot();
        string rootBackup = Combine(root, $"Backups/Crashed/{timeStamp}/");
        string rootOrigin = Combine(root, "Saves/");

        // Create new directories
        CreateDirectory(rootBackup);
        CreateDirectory(rootBackup, "Accounts/");
        CreateDirectory(rootBackup, "Items/");
        CreateDirectory(rootBackup, "Mobiles/");
        CreateDirectory(rootBackup, "Guilds/");
        CreateDirectory(rootBackup, "Regions/");

        // Copy files
        CopyFile(rootOrigin, rootBackup, "Accounts/Accounts.xml");

        CopyFile(rootOrigin, rootBackup, "Items/Items.bin");
        CopyFile(rootOrigin, rootBackup, "Items/Items.idx");
        CopyFile(rootOrigin, rootBackup, "Items/Items.tdb");

        CopyFile(rootOrigin, rootBackup, "Mobiles/Mobiles.bin");
        CopyFile(rootOrigin, rootBackup, "Mobiles/Mobiles.idx");
        CopyFile(rootOrigin, rootBackup, "Mobiles/Mobiles.tdb");

        CopyFile(rootOrigin, rootBackup, "Guilds/Guilds.bin");
        CopyFile(rootOrigin, rootBackup, "Guilds/Guilds.idx");

        CopyFile(rootOrigin, rootBackup, "Regions/Regions.bin");
        CopyFile(rootOrigin, rootBackup, "Regions/Regions.idx");

        Console.WriteLine("done");
      }
      catch
      {
        Console.WriteLine("failed");
      }
    }

    private static void GenerateCrashReport(CrashedEventArgs e)
    {
      Console.Write("Crash: Generating report...");

      try
      {
        string timeStamp = GetTimeStamp();
        string fileName = $"Crash {timeStamp}.log";

        string root = GetRoot();
        string filePath = Combine(root, fileName);

        using (StreamWriter op = new StreamWriter(filePath))
        {
          Version ver = Core.Assembly.GetName().Version;

          op.WriteLine("Server Crash Report");
          op.WriteLine("===================");
          op.WriteLine();
          op.WriteLine("ModernUO Version {0}.{1}, Build {2}.{3}", ver.Major, ver.Minor, ver.Build, ver.Revision);
          op.WriteLine("Operating System: {0}", Environment.OSVersion);
          op.WriteLine(".NET Framework: {0}", Environment.Version);
          op.WriteLine("Time: {0}", DateTime.UtcNow);

          try
          {
            op.WriteLine("Mobiles: {0}", World.Mobiles.Count);
          }
          catch
          {
            // ignored
          }

          try
          {
            op.WriteLine("Items: {0}", World.Items.Count);
          }
          catch
          {
            // ignored
          }

          op.WriteLine("Exception:");
          op.WriteLine(e.Exception);
          op.WriteLine();

          op.WriteLine("Clients:");

          try
          {
            List<NetState> states = NetState.Instances;

            op.WriteLine("- Count: {0}", states.Count);

            for (int i = 0; i < states.Count; ++i)
            {
              NetState state = states[i];

              op.Write("+ {0}:", state);

              if (state.Account is Account a)
                op.Write(" (account = {0})", a.Username);

              Mobile m = state.Mobile;

              if (m != null)
                op.Write(" (mobile = 0x{0:X} '{1}')", m.Serial.Value, m.Name);

              op.WriteLine();
            }
          }
          catch
          {
            op.WriteLine("- Failed");
          }
        }

        Console.WriteLine("done");

        if (Email.FROM_ADDRESS != null && Email.CRASH_ADDRESS != null)
          SendEmail(filePath);
      }
      catch
      {
        Console.WriteLine("failed");
      }
    }

    private static string GetTimeStamp()
    {
      DateTime now = DateTime.UtcNow;

      return $"{now.Day}-{now.Month}-{now.Year}-{now.Hour}-{now.Minute}-{now.Second}";
    }
  }
}