/***************************************************************************
 *                                Commands.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 Server.Network;

namespace Server
{
  public delegate void CommandEventHandler(CommandEventArgs e);

  public class CommandEventArgs : EventArgs
  {
    public CommandEventArgs(Mobile mobile, string command, string argString, string[] arguments)
    {
      Mobile = mobile;
      Command = command;
      ArgString = argString;
      Arguments = arguments;
    }

    public Mobile Mobile { get; }

    public string Command { get; }

    public string ArgString { get; }

    public string[] Arguments { get; }

    public int Length => Arguments.Length;

    public string GetString(int index)
    {
      if (index < 0 || index >= Arguments.Length)
        return "";

      return Arguments[index];
    }

    public int GetInt32(int index)
    {
      if (index < 0 || index >= Arguments.Length)
        return 0;

      return Utility.ToInt32(Arguments[index]);
    }

    public uint GetUInt32(int index)
    {
      if (index < 0 || index >= Arguments.Length)
        return 0;

      return Utility.ToUInt32(Arguments[index]);
    }

    public bool GetBoolean(int index)
    {
      if (index < 0 || index >= Arguments.Length)
        return false;

      return Utility.ToBoolean(Arguments[index]);
    }

    public double GetDouble(int index)
    {
      if (index < 0 || index >= Arguments.Length)
        return 0.0;

      return Utility.ToDouble(Arguments[index]);
    }

    public TimeSpan GetTimeSpan(int index)
    {
      if (index < 0 || index >= Arguments.Length)
        return TimeSpan.Zero;

      return Utility.ToTimeSpan(Arguments[index]);
    }
  }

  public static partial class EventSink
  {
    public static event Action<CommandEventArgs> Command;
    public static void InvokeCommand(CommandEventArgs e) => Command?.Invoke(e);
  }

  public class CommandEntry : IComparable<CommandEntry>
  {
    public CommandEntry(string command, CommandEventHandler handler, AccessLevel accessLevel)
    {
      Command = command;
      Handler = handler;
      AccessLevel = accessLevel;
    }

    public string Command { get; }

    public CommandEventHandler Handler { get; }

    public AccessLevel AccessLevel { get; }

    public int CompareTo(CommandEntry e) => e == null ? 1 : Command.CompareTo(e.Command);
  }

  public static class CommandSystem
  {
    public static string Prefix { get; set; } = "[";

    public static Dictionary<string, CommandEntry> Entries { get; } =
      new Dictionary<string, CommandEntry>(StringComparer.OrdinalIgnoreCase);

    public static AccessLevel BadCommandIgnoreLevel { get; set; } = AccessLevel.Player;

    public static string[] Split(string value)
    {
      var array = value.ToCharArray();
      var list = new List<string>();

      var start = 0;

      while (start < array.Length)
      {
        var c = array[start];

        if (c == '"')
        {
          ++start;
          var end = start;

          while (end < array.Length)
            if (array[end] != '"' || array[end - 1] == '\\')
              ++end;
            else
              break;

          list.Add(value.Substring(start, end - start));

          start = end + 2;
        }
        else if (c != ' ')
        {
          var end = start;

          while (end < array.Length)
            if (array[end] != ' ')
              ++end;
            else
              break;

          list.Add(value.Substring(start, end - start));

          start = end + 1;
        }
        else
        {
          ++start;
        }
      }

      return list.ToArray();
    }

    public static void Register(string command, AccessLevel access, CommandEventHandler handler)
    {
      Entries[command] = new CommandEntry(command, handler, access);
    }

    public static bool Handle(Mobile from, string text, MessageType type = MessageType.Regular)
    {
      if (!text.StartsWith(Prefix) && type != MessageType.Command)
        return false;

      if (type != MessageType.Command)
        text = text.Substring(Prefix.Length);

      var indexOf = text.IndexOf(' ');

      string command;
      string[] args;
      string argString;

      if (indexOf >= 0)
      {
        argString = text.Substring(indexOf + 1);

        command = text.Substring(0, indexOf);
        args = Split(argString);
      }
      else
      {
        argString = "";
        command = text.ToLower();
        args = Array.Empty<string>();
      }

      Entries.TryGetValue(command, out var entry);

      if (entry != null)
      {
        if (from.AccessLevel >= entry.AccessLevel)
        {
          if (entry.Handler != null)
          {
            var e = new CommandEventArgs(from, command, argString, args);
            entry.Handler(e);
            EventSink.InvokeCommand(e);
          }
        }
        else
        {
          if (from.AccessLevel <= BadCommandIgnoreLevel)
            return false;

          from.SendMessage("You do not have access to that command.");
        }
      }
      else
      {
        if (from.AccessLevel <= BadCommandIgnoreLevel)
          return false;

        from.SendMessage("That is not a valid command.");
      }

      return true;
    }
  }
}