/***************************************************************************
 *                                 World.cs
 *                            -------------------
 *   begin                : May 1, 2002
 *   copyright            : (C) The RunUO Software Team
 *   email                : info@runuo.com
 *
 *   $Id$
 *
 ***************************************************************************/

/***************************************************************************
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 ***************************************************************************/

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Reflection;
using System.Threading;
using Server.Guilds;
using Server.Network;

namespace Server
{
  public static class World
  {
    private static readonly ManualResetEvent m_DiskWriteHandle = new ManualResetEvent(true);

    private static Queue<IEntity> _addQueue, _deleteQueue;

    public static readonly string MobileIndexPath = Path.Combine("Saves/Mobiles/", "Mobiles.idx");
    public static readonly string MobileTypesPath = Path.Combine("Saves/Mobiles/", "Mobiles.tdb");
    public static readonly string MobileDataPath = Path.Combine("Saves/Mobiles/", "Mobiles.bin");

    public static readonly string ItemIndexPath = Path.Combine("Saves/Items/", "Items.idx");
    public static readonly string ItemTypesPath = Path.Combine("Saves/Items/", "Items.tdb");
    public static readonly string ItemDataPath = Path.Combine("Saves/Items/", "Items.bin");

    public static readonly string GuildIndexPath = Path.Combine("Saves/Guilds/", "Guilds.idx");
    public static readonly string GuildDataPath = Path.Combine("Saves/Guilds/", "Guilds.bin");

    private static readonly Type[] m_SerialTypeArray = { typeof(Serial) };

    internal static int m_Saves;

    internal static List<Type> m_ItemTypes = new List<Type>();
    internal static List<Type> m_MobileTypes = new List<Type>();

    public static bool Saving{ get; private set; }

    public static bool Loaded{ get; private set; }

    public static bool Loading{ get; private set; }

    public static Dictionary<Serial, Mobile> Mobiles{ get; private set; }

    public static Dictionary<Serial, Item> Items{ get; private set; }

    public static string LoadingType{ get; private set; }

    public static void NotifyDiskWriteComplete()
    {
      if (m_DiskWriteHandle.Set()) Console.WriteLine("Closing Save Files. ");
    }

    public static void WaitForWriteCompletion()
    {
      m_DiskWriteHandle.WaitOne();
    }

    public static bool OnDelete(IEntity entity)
    {
      if (Saving || Loading)
      {
        if (Saving) AppendSafetyLog("delete", entity);

        _deleteQueue.Enqueue(entity);

        return false;
      }

      return true;
    }

    public static void Broadcast(int hue, bool ascii, string text)
    {
      Packet p;

      if (ascii)
        p = new AsciiMessage(Serial.MinusOne, -1, MessageType.Regular, hue, 3, "System", text);
      else
        p = new UnicodeMessage(Serial.MinusOne, -1, MessageType.Regular, hue, 3, "ENU", "System", text);

      List<NetState> list = TcpServer.Instances;

      p.Acquire();

      for (int i = 0; i < list.Count; ++i)
        if (list[i].Mobile != null)
          list[i].Send(p);

      p.Release();
    }

    public static void Broadcast(int hue, bool ascii, string format, params object[] args)
    {
      Broadcast(hue, ascii, string.Format(format, args));
    }

    private static List<Tuple<ConstructorInfo, string>> ReadTypes(BinaryReader tdbReader)
    {
      int count = tdbReader.ReadInt32();

      List<Tuple<ConstructorInfo, string>> types = new List<Tuple<ConstructorInfo, string>>(count);

      for (int i = 0; i < count; ++i)
      {
        string typeName = tdbReader.ReadString();

        Type t = AssemblyHandler.FindFirstTypeForName(typeName);

        if (t == null)
        {
          Console.WriteLine("failed");

          if (!Core.Service)
          {
            Console.WriteLine("Error: Type '{0}' was not found. Delete all of those types? (y/n)", typeName);

            if (Console.ReadKey(true).Key == ConsoleKey.Y)
            {
              types.Add(null);
              Console.Write("World: Loading...");
              continue;
            }

            Console.WriteLine("Types will not be deleted. An exception will be thrown.");
          }
          else
          {
            Console.WriteLine("Error: Type '{0}' was not found.", typeName);
          }

          throw new Exception($"Bad type '{typeName}'");
        }

        ConstructorInfo ctor = t.GetConstructor(m_SerialTypeArray);

        if (ctor != null)
          types.Add(new Tuple<ConstructorInfo, string>(ctor, typeName));
        else
          throw new Exception($"Type '{t}' does not have a serialization constructor");
      }

      return types;
    }

    public static void Load()
    {
      if (Loaded)
        return;

      Loaded = true;
      LoadingType = null;

      Console.Write("World: Loading...");

      Stopwatch watch = Stopwatch.StartNew();

      Loading = true;

      _addQueue = new Queue<IEntity>();
      _deleteQueue = new Queue<IEntity>();

      int mobileCount, itemCount, guildCount;

      object[] ctorArgs = new object[1];

      List<ItemEntry> items = new List<ItemEntry>();
      List<MobileEntry> mobiles = new List<MobileEntry>();
      List<GuildEntry> guilds = new List<GuildEntry>();

      if (File.Exists(MobileIndexPath) && File.Exists(MobileTypesPath))
      {
        using FileStream idx = new FileStream(MobileIndexPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        BinaryReader idxReader = new BinaryReader(idx);

        using (FileStream tdb = new FileStream(MobileTypesPath, FileMode.Open, FileAccess.Read, FileShare.Read))
        {
          BinaryReader tdbReader = new BinaryReader(tdb);

          List<Tuple<ConstructorInfo, string>> types = ReadTypes(tdbReader);

          mobileCount = idxReader.ReadInt32();

          Mobiles = new Dictionary<Serial, Mobile>(mobileCount);

          for (int i = 0; i < mobileCount; ++i)
          {
            int typeID = idxReader.ReadInt32();
            uint serial = idxReader.ReadUInt32();
            long pos = idxReader.ReadInt64();
            int length = idxReader.ReadInt32();

            Tuple<ConstructorInfo, string> objs = types[typeID];

            if (objs == null)
              continue;

            Mobile m = null;
            ConstructorInfo ctor = objs.Item1;
            string typeName = objs.Item2;

            try
            {
              ctorArgs[0] = (Serial)serial;
              m = (Mobile)ctor.Invoke(ctorArgs);
            }
            catch
            {
              // ignored
            }

            if (m != null)
            {
              mobiles.Add(new MobileEntry(m, typeID, typeName, pos, length));
              AddMobile(m);
            }
          }

          tdbReader.Close();
        }

        idxReader.Close();
      }
      else
        Mobiles = new Dictionary<Serial, Mobile>();

      if (File.Exists(ItemIndexPath) && File.Exists(ItemTypesPath))
      {
        using FileStream idx = new FileStream(ItemIndexPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        BinaryReader idxReader = new BinaryReader(idx);

        using (FileStream tdb = new FileStream(ItemTypesPath, FileMode.Open, FileAccess.Read, FileShare.Read))
        {
          BinaryReader tdbReader = new BinaryReader(tdb);

          List<Tuple<ConstructorInfo, string>> types = ReadTypes(tdbReader);

          itemCount = idxReader.ReadInt32();

          Items = new Dictionary<Serial, Item>(itemCount);

          for (int i = 0; i < itemCount; ++i)
          {
            int typeID = idxReader.ReadInt32();
            uint serial = idxReader.ReadUInt32();
            long pos = idxReader.ReadInt64();
            int length = idxReader.ReadInt32();

            Tuple<ConstructorInfo, string> objs = types[typeID];

            if (objs == null)
              continue;

            Item item = null;
            ConstructorInfo ctor = objs.Item1;
            string typeName = objs.Item2;

            try
            {
              ctorArgs[0] = (Serial)serial;
              item = (Item)ctor.Invoke(ctorArgs);
            }
            catch
            {
              // ignored
            }

            if (item != null)
            {
              items.Add(new ItemEntry(item, typeID, typeName, pos, length));
              AddItem(item);
            }
          }

          tdbReader.Close();
        }

        idxReader.Close();
      }
      else
        Items = new Dictionary<Serial, Item>();

      if (File.Exists(GuildIndexPath))
      {
        using FileStream idx = new FileStream(GuildIndexPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        BinaryReader idxReader = new BinaryReader(idx);

        guildCount = idxReader.ReadInt32();

        CreateGuildEventArgs createEventArgs = new CreateGuildEventArgs(0xFFFFFFFF);
        for (int i = 0; i < guildCount; ++i)
        {
          idxReader.ReadInt32(); //no typeid for guilds
          uint id = idxReader.ReadUInt32();
          long pos = idxReader.ReadInt64();
          int length = idxReader.ReadInt32();

          createEventArgs.Id = id;
          EventSink.InvokeCreateGuild(createEventArgs);
          BaseGuild guild = createEventArgs.Guild;
          if (guild != null)
            guilds.Add(new GuildEntry(guild, pos, length));
        }

        idxReader.Close();
      }

      bool failedMobiles = false, failedItems = false, failedGuilds = false;
      Type failedType = null;
      Serial failedSerial = Serial.Zero;
      Exception failed = null;
      int failedTypeID = 0;

      if (File.Exists(MobileDataPath))
      {
        using FileStream bin = new FileStream(MobileDataPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        BinaryFileReader reader = new BinaryFileReader(new BinaryReader(bin));

        for (int i = 0; i < mobiles.Count; ++i)
        {
          MobileEntry entry = mobiles[i];
          Mobile m = entry.Mobile;

          if (m != null)
          {
            reader.Seek(entry.Position, SeekOrigin.Begin);

            try
            {
              LoadingType = entry.TypeName;
              m.Deserialize(reader);

              if (reader.Position != entry.Position + entry.Length)
                throw new Exception($"***** Bad serialize on {m.GetType()} *****");
            }
            catch (Exception e)
            {
              mobiles.RemoveAt(i);

              failed = e;
              failedMobiles = true;
              failedType = m.GetType();
              failedTypeID = entry.TypeID;
              failedSerial = m.Serial;

              break;
            }
          }
        }

        reader.Close();
      }

      if (!failedMobiles && File.Exists(ItemDataPath))
      {
        using FileStream bin = new FileStream(ItemDataPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        BinaryFileReader reader = new BinaryFileReader(new BinaryReader(bin));

        for (int i = 0; i < items.Count; ++i)
        {
          ItemEntry entry = items[i];
          Item item = entry.Item;

          if (item != null)
          {
            reader.Seek(entry.Position, SeekOrigin.Begin);

            try
            {
              LoadingType = entry.TypeName;
              item.Deserialize(reader);

              if (reader.Position != entry.Position + entry.Length)
                throw new Exception($"***** Bad serialize on {item.GetType()} *****");
            }
            catch (Exception e)
            {
              items.RemoveAt(i);

              failed = e;
              failedItems = true;
              failedType = item.GetType();
              failedTypeID = entry.TypeID;
              failedSerial = item.Serial;

              break;
            }
          }
        }

        reader.Close();
      }

      LoadingType = null;

      if (!failedMobiles && !failedItems && File.Exists(GuildDataPath))
      {
        using FileStream bin = new FileStream(GuildDataPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        BinaryFileReader reader = new BinaryFileReader(new BinaryReader(bin));

        for (int i = 0; i < guilds.Count; ++i)
        {
          GuildEntry entry = guilds[i];
          BaseGuild g = entry.Guild;

          if (g != null)
          {
            reader.Seek(entry.Position, SeekOrigin.Begin);

            try
            {
              g.Deserialize(reader);

              if (reader.Position != entry.Position + entry.Length)
                throw new Exception($"***** Bad serialize on Guild {g.Id} *****");
            }
            catch (Exception e)
            {
              guilds.RemoveAt(i);

              failed = e;
              failedGuilds = true;
              failedType = typeof(BaseGuild);
              failedTypeID = (int)g.Id;
              failedSerial = g.Id;

              break;
            }
          }
        }

        reader.Close();
      }

      if (failedItems || failedMobiles || failedGuilds)
      {
        Console.WriteLine("An error was encountered while loading a saved object");

        Console.WriteLine(" - Type: {0}", failedType);
        Console.WriteLine(" - Serial: {0}", failedSerial);

        if (!Core.Service)
        {
          Console.WriteLine("Delete the object? (y/n)");

          if (Console.ReadKey(true).Key == ConsoleKey.Y)
          {
            if (failedType != typeof(BaseGuild))
            {
              Console.WriteLine("Delete all objects of that type? (y/n)");

              if (Console.ReadKey(true).Key == ConsoleKey.Y)
              {
                if (failedMobiles)
                  for (int i = 0; i < mobiles.Count;)
                    if (mobiles[i].TypeID == failedTypeID)
                      mobiles.RemoveAt(i);
                    else
                      ++i;
                else if (failedItems)
                  for (int i = 0; i < items.Count;)
                    if (items[i].TypeID == failedTypeID)
                      items.RemoveAt(i);
                    else
                      ++i;
              }
            }

            SaveIndex(mobiles, MobileIndexPath);
            SaveIndex(items, ItemIndexPath);
            SaveIndex(guilds, GuildIndexPath);
          }

          Console.WriteLine("After pressing return an exception will be thrown and the server will terminate.");
          Console.ReadLine();
        }
        else
        {
          Console.WriteLine("An exception will be thrown and the server will terminate.");
        }

        throw new Exception(
          $"Load failed (items={failedItems}, mobiles={failedMobiles}, guilds={failedGuilds}, type={failedType}, serial={failedSerial})",
          failed);
      }

      EventSink.InvokeWorldLoad();

      Loading = false;

      ProcessSafetyQueues();

      foreach (Item item in Items.Values)
      {
        if (item.Parent == null)
          item.UpdateTotals();

        item.ClearProperties();
      }

      foreach (Mobile m in Mobiles.Values)
      {
        m.UpdateRegion(); // Is this really needed?
        m.UpdateTotals();

        m.ClearProperties();
      }

      watch.Stop();

      Console.WriteLine("done ({1} items, {2} mobiles) ({0:F2} seconds)", watch.Elapsed.TotalSeconds, Items.Count,
        Mobiles.Count);
    }

    private static void ProcessSafetyQueues()
    {
      while (_addQueue.Count > 0)
      {
        IEntity entity = _addQueue.Dequeue();

        if (entity is Item item)
          AddItem(item);
        else if (entity is Mobile mob)
          AddMobile(mob);
      }

      while (_deleteQueue.Count > 0)
      {
        IEntity entity = _deleteQueue.Dequeue();

        if (entity is Item item)
          item.Delete();
        else if (entity is Mobile mob)
          mob.Delete();
      }
    }

    private static void AppendSafetyLog(string action, IEntity entity)
    {
      string message =
        $"Warning: Attempted to {action} {entity} during world save.{Environment.NewLine}This action could cause inconsistent state.{Environment.NewLine}It is strongly advised that the offending scripts be corrected.";

      Console.WriteLine(message);

      try
      {
        using StreamWriter op = new StreamWriter("world-save-errors.log", true);
        op.WriteLine("{0}\t{1}", DateTime.UtcNow, message);
        op.WriteLine(new StackTrace(2).ToString());
        op.WriteLine();
      }
      catch
      {
        // ignored
      }
    }

    private static void SaveIndex<T>(List<T> list, string path) where T : IEntityEntry
    {
      if (!Directory.Exists("Saves/Mobiles/"))
        Directory.CreateDirectory("Saves/Mobiles/");

      if (!Directory.Exists("Saves/Items/"))
        Directory.CreateDirectory("Saves/Items/");

      if (!Directory.Exists("Saves/Guilds/"))
        Directory.CreateDirectory("Saves/Guilds/");

      using FileStream idx = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.None);
      BinaryWriter idxWriter = new BinaryWriter(idx);

      idxWriter.Write(list.Count);

      for (int i = 0; i < list.Count; ++i)
      {
        T e = list[i];

        idxWriter.Write(e.TypeID);
        idxWriter.Write(e.Serial);
        idxWriter.Write(e.Position);
        idxWriter.Write(e.Length);
      }

      idxWriter.Close();
    }

    public static void Save()
    {
      Save(true, false);
    }

    public static void Save(bool message, bool permitBackgroundWrite)
    {
      if (Saving)
        return;

      ++m_Saves;

      NetState.Pause();

      WaitForWriteCompletion(); //Blocks Save until current disk flush is done.

      Saving = true;

      m_DiskWriteHandle.Reset();

      if (message)
        Broadcast(0x35, true, "The world is saving, please wait.");

      SaveStrategy strategy = SaveStrategy.Acquire();
      Console.WriteLine("Core: Using {0} save strategy", strategy.Name.ToLowerInvariant());

      Console.Write($"[{DateTime.UtcNow.ToLongTimeString()}] World: Saving...");

      Stopwatch watch = Stopwatch.StartNew();

      if (!Directory.Exists("Saves/Mobiles/"))
        Directory.CreateDirectory("Saves/Mobiles/");
      if (!Directory.Exists("Saves/Items/"))
        Directory.CreateDirectory("Saves/Items/");
      if (!Directory.Exists("Saves/Guilds/"))
        Directory.CreateDirectory("Saves/Guilds/");


      strategy.Save(permitBackgroundWrite);

      try
      {
        EventSink.InvokeWorldSave(message);
      }
      catch (Exception e)
      {
        throw new Exception("World Save event threw an exception.  Save failed!", e);
      }

      watch.Stop();

      Saving = false;

      if (!permitBackgroundWrite)
        NotifyDiskWriteComplete(); //Sets the DiskWriteHandle.  If we allow background writes, we leave this upto the individual save strategies.

      ProcessSafetyQueues();

      strategy.ProcessDecay();

      Console.WriteLine("Save done in {0:F2} seconds.", watch.Elapsed.TotalSeconds);

      if (message)
        Broadcast(0x35, true, "World save complete. The entire process took {0:F1} seconds.",
          watch.Elapsed.TotalSeconds);

      NetState.Resume();
    }

    public static IEntity FindEntity(Serial serial)
    {
      if (serial.IsItem)
        return FindItem(serial);
      if (serial.IsMobile)
        return FindMobile(serial);

      return null;
    }

    public static Mobile FindMobile(Serial serial)
    {
      Mobiles.TryGetValue(serial, out Mobile mob);

      return mob;
    }

    public static void AddMobile(Mobile m)
    {
      if (Saving)
      {
        AppendSafetyLog("add", m);
        _addQueue.Enqueue(m);
      }
      else
      {
        Mobiles.Add(m.Serial, m);
      }
    }

    public static Item FindItem(Serial serial)
    {
      Items.TryGetValue(serial, out Item item);

      return item;
    }

    public static void AddItem(Item item)
    {
      if (Saving)
      {
        AppendSafetyLog("add", item);
        _addQueue.Enqueue(item);
      }
      else
      {
        Items.Add(item.Serial, item);
      }
    }

    public static void RemoveMobile(Mobile m)
    {
      Mobiles.Remove(m.Serial);
    }

    public static void RemoveItem(Item item)
    {
      Items.Remove(item.Serial);
    }

    private interface IEntityEntry
    {
      Serial Serial{ get; }
      int TypeID{ get; }
      long Position{ get; }
      int Length{ get; }
    }

    private sealed class GuildEntry : IEntityEntry
    {
      public GuildEntry(BaseGuild g, long pos, int length)
      {
        Guild = g;
        Position = pos;
        Length = length;
      }

      public BaseGuild Guild{ get; }

      public Serial Serial => Guild?.Id ?? 0;

      public int TypeID => 0;

      public long Position{ get; }

      public int Length{ get; }
    }

    private sealed class ItemEntry : IEntityEntry
    {
      public ItemEntry(Item item, int typeID, string typeName, long pos, int length)
      {
        Item = item;
        TypeID = typeID;
        TypeName = typeName;
        Position = pos;
        Length = length;
      }

      public Item Item{ get; }

      public string TypeName{ get; }

      public Serial Serial => Item?.Serial ?? Serial.MinusOne;

      public int TypeID{ get; }

      public long Position{ get; }

      public int Length{ get; }
    }

    private sealed class MobileEntry : IEntityEntry
    {
      public MobileEntry(Mobile mobile, int typeID, string typeName, long pos, int length)
      {
        Mobile = mobile;
        TypeID = typeID;
        TypeName = typeName;
        Position = pos;
        Length = length;
      }

      public Mobile Mobile{ get; }

      public string TypeName{ get; }

      public Serial Serial => Mobile?.Serial ?? Serial.MinusOne;

      public int TypeID{ get; }

      public long Position{ get; }

      public int Length{ get; }
    }
  }
}