/*************************************************************************
 * ModernUO                                                              *
 * Copyright 2019-2020 - ModernUO Development Team                       *
 * Email: hi@modernuo.com                                                *
 * File: OutgoingEntityPackets.cs                                        *
 *                                                                       *
 * 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 3 of the License, or     *
 * (at your option) any later version.                                   *
 *                                                                       *
 * You should have received a copy of the GNU General Public License     *
 * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 *************************************************************************/

using System;
using System.Buffers;
using Server.Items;

namespace Server.Network
{
    public static class OutgoingEntityPackets
    {
        public const int OPLPacketLength = 9;
        public const int RemoveEntityLength = 5;
        public const int MaxWorldEntityPacketLength = 26;

        public static void CreateOPLInfo(Span<byte> buffer, Item item) =>
            CreateOPLInfo(buffer, item.Serial, item.PropertyList.Hash);

        public static void CreateOPLInfo(Span<byte> buffer, Serial serial, int hash)
        {
            if (buffer[0] != 0)
            {
                return;
            }

            var writer = new SpanWriter(buffer);
            writer.Write((byte)0xDC); // Packet ID
            writer.Write(serial);
            writer.Write(hash);
        }

        public static void SendOPLInfo(this NetState ns, IPropertyListObject obj) =>
            ns.SendOPLInfo(obj.Serial, obj.PropertyList.Hash);

        public static void SendOPLInfo(this NetState ns, Serial serial, int hash)
        {
            if (ns == null)
            {
                return;
            }

            Span<byte> buffer = stackalloc byte[OPLPacketLength].InitializePacket();
            CreateOPLInfo(buffer, serial, hash);

            ns.Send(buffer);
        }

        public static void CreateRemoveEntity(Span<byte> buffer, Serial serial)
        {
            if (buffer[0] != 0)
            {
                return;
            }

            var writer = new SpanWriter(buffer);
            writer.Write((byte)0x1D); // Packet ID
            writer.Write(serial);
        }

        public static void SendRemoveEntity(this NetState ns, Serial serial)
        {
            if (ns == null)
            {
                return;
            }

            Span<byte> buffer = stackalloc byte[RemoveEntityLength].InitializePacket();
            CreateRemoveEntity(buffer, serial);

            ns.Send(buffer);
        }

        public static int CreateWorldEntity(Span<byte> buffer, IEntity entity, bool isHS)
        {
            if (buffer[0] != 0)
            {
                return buffer.Length;
            }

            var writer = new SpanWriter(buffer);
            writer.Write((byte)0xF3); // Packet ID
            writer.Write((short)0x1); // command

            int type = 0;
            int gfx = 0;
            int amount = 1;
            int hue = 0;
            byte light = 0;
            int flags = 0;

            if (entity is BaseMulti multi)
            {
                type = 2;
                gfx = multi.ItemID & (isHS ? 0xFFFF : 0x7FFF);
                hue = multi.Hue;
                amount = multi.Amount;
            }
            else if (entity is Item item)
            {
                // type = 3 if is damageable
                gfx = item.ItemID & (isHS ? 0xFFFF : 0x7FFF);
                hue = item.Hue;
                amount = item.Amount;
                light = (byte)item.Light;
                flags = item.GetPacketFlags();
            }
            else if (entity is Mobile mobile)
            {
                type = 1;
                gfx = mobile.BodyValue;
                hue = mobile.Hue;
                flags = mobile.GetPacketFlags(true);
            }

            writer.Write((byte)type);
            writer.Write(entity.Serial);
            writer.Write((ushort)gfx);
            writer.Write((byte)0);

            writer.Write((short)amount); // Min
            writer.Write((short)amount); // Max

            writer.Write((short)(entity.X & 0x7FFF));
            writer.Write((short)(entity.Y & 0x3FFF));
            writer.Write((sbyte)entity.Z);

            writer.Write(light);
            writer.Write((short)hue);
            writer.Write((byte)flags);

            if (isHS)
            {
                writer.Write((short)0);
            }

            return writer.Position;
        }
    }
}
