/***************************************************************************
 *                                Target.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 Server.Network;

namespace Server.Targeting
{
  public abstract class Target
  {
    private static int m_NextTargetID;

    private Timer m_TimeoutTimer;

    protected Target(int range, bool allowGround, TargetFlags flags)
    {
      TargetID = ++m_NextTargetID;
      Range = range;
      AllowGround = allowGround;
      Flags = flags;

      CheckLOS = true;
    }

    public DateTime TimeoutTime{ get; private set; }

    public bool CheckLOS{ get; set; }

    public bool DisallowMultis{ get; set; }

    public bool AllowNonlocal{ get; set; }

    public int TargetID{ get; }

    public int Range{ get; set; }

    public bool AllowGround{ get; set; }

    public TargetFlags Flags{ get; set; }

    public static void Cancel(Mobile m)
    {
      m.NetState?.Send(CancelTarget.Instance);
      m.Target?.OnTargetCancel(m, TargetCancelType.Canceled);
    }

    public void BeginTimeout(Mobile from, TimeSpan delay)
    {
      TimeoutTime = DateTime.UtcNow + delay;

      m_TimeoutTimer?.Stop();

      m_TimeoutTimer = new TimeoutTimer(this, from, delay);
      m_TimeoutTimer.Start();
    }

    public void CancelTimeout()
    {
      m_TimeoutTimer?.Stop();
      m_TimeoutTimer = null;
    }

    public void Timeout(Mobile from)
    {
      CancelTimeout();
      from.ClearTarget();

      Cancel(from);

      OnTargetCancel(from, TargetCancelType.Timeout);
      OnTargetFinish(from);
    }

    public virtual Packet GetPacketFor(NetState ns) => new TargetReq(this);

    public void Cancel(Mobile from, TargetCancelType type)
    {
      CancelTimeout();
      from.ClearTarget();

      OnTargetCancel(from, type);
      OnTargetFinish(from);
    }

    public void Invoke(Mobile from, object targeted)
    {
      CancelTimeout();
      from.ClearTarget();

      if (from.Deleted)
      {
        OnTargetCancel(from, TargetCancelType.Canceled);
        OnTargetFinish(from);
        return;
      }

      Point3D loc;
      Map map;

      Item item = targeted as Item;
      Mobile mobile = targeted as Mobile;

      if (targeted is LandTarget target)
      {
        loc = target.Location;
        map = from.Map;
      }
      else if (targeted is StaticTarget staticTarget)
      {
        loc = staticTarget.Location;
        map = from.Map;
      }
      else if (mobile != null)
      {
        if (mobile.Deleted)
        {
          OnTargetDeleted(from, mobile);
          OnTargetFinish(from);
          return;
        }

        if (!mobile.CanTarget)
        {
          OnTargetUntargetable(from, mobile);
          OnTargetFinish(from);
          return;
        }

        loc = mobile.Location;
        map = mobile.Map;
      }
      else if (item != null)
      {
        if (item.Deleted)
        {
          OnTargetDeleted(from, item);
          OnTargetFinish(from);
          return;
        }

        if (!item.CanTarget)
        {
          OnTargetUntargetable(from, item);
          OnTargetFinish(from);
          return;
        }

        if (!AllowNonlocal && item.RootParent is Mobile && item.RootParent != from && from.AccessLevel == AccessLevel.Player)
        {
          OnNonlocalTarget(from, item);
          OnTargetFinish(from);
          return;
        }

        loc = item.GetWorldLocation();
        map = item.Map;
      }
      else
      {
        OnTargetCancel(from, TargetCancelType.Canceled);
        OnTargetFinish(from);
        return;
      }

      if (map == null || map != from.Map || Range != -1 && !from.InRange(loc, Range))
      {
        OnTargetOutOfRange(from, targeted);
      }
      else
      {
        if (!from.CanSee(targeted))
          OnCantSeeTarget(from, targeted);
        else if (CheckLOS && !from.InLOS(targeted))
          OnTargetOutOfLOS(from, targeted);
        else if (item?.InSecureTrade == true)
          OnTargetInSecureTrade(from, targeted);
        else if (item?.IsAccessibleTo(from) == false)
          OnTargetNotAccessible(from, targeted);
        else if (item?.CheckTarget(from, this, targeted) == false)
          OnTargetUntargetable(from, targeted);
        else if (mobile?.CheckTarget(from, this, mobile) == false)
          OnTargetUntargetable(from, mobile);
        else if (from.Region.OnTarget(from, this, targeted))
          OnTarget(from, targeted);
      }

      OnTargetFinish(from);
    }

    protected virtual void OnTarget(Mobile from, object targeted)
    {
    }

    protected virtual void OnTargetNotAccessible(Mobile from, object targeted)
    {
      from.SendLocalizedMessage(500447); // That is not accessible.
    }

    protected virtual void OnTargetInSecureTrade(Mobile from, object targeted)
    {
      from.SendLocalizedMessage(500447); // That is not accessible.
    }

    protected virtual void OnNonlocalTarget(Mobile from, object targeted)
    {
      from.SendLocalizedMessage(500447); // That is not accessible.
    }

    protected virtual void OnCantSeeTarget(Mobile from, object targeted)
    {
      from.SendLocalizedMessage(500237); // Target can not be seen.
    }

    protected virtual void OnTargetOutOfLOS(Mobile from, object targeted)
    {
      from.SendLocalizedMessage(500237); // Target can not be seen.
    }

    protected virtual void OnTargetOutOfRange(Mobile from, object targeted)
    {
      from.SendLocalizedMessage(500446); // That is too far away.
    }

    protected virtual void OnTargetDeleted(Mobile from, object targeted)
    {
    }

    protected virtual void OnTargetUntargetable(Mobile from, object targeted)
    {
      from.SendLocalizedMessage(500447); // That is not accessible.
    }

    protected virtual void OnTargetCancel(Mobile from, TargetCancelType cancelType)
    {
    }

    protected virtual void OnTargetFinish(Mobile from)
    {
    }

    private class TimeoutTimer : Timer
    {
      private static TimeSpan ThirtySeconds = TimeSpan.FromSeconds(30.0);
      private static TimeSpan TenSeconds = TimeSpan.FromSeconds(10.0);
      private static TimeSpan OneSecond = TimeSpan.FromSeconds(1.0);
      private Mobile m_Mobile;
      private Target m_Target;

      public TimeoutTimer(Target target, Mobile m, TimeSpan delay) : base(delay)
      {
        m_Target = target;
        m_Mobile = m;

        if (delay >= ThirtySeconds)
          Priority = TimerPriority.FiveSeconds;
        else if (delay >= TenSeconds)
          Priority = TimerPriority.OneSecond;
        else if (delay >= OneSecond)
          Priority = TimerPriority.TwoFiftyMS;
        else
          Priority = TimerPriority.TwentyFiveMS;
      }

      protected override void OnTick()
      {
        if (m_Mobile.Target == m_Target)
          m_Target.Timeout(m_Mobile);
      }
    }
  }
}