using System;
using System.Buffers;
using System.IO;
using Server.ContextMenus;
using Server.Menus.ItemLists;
using Server.Menus.Questions;

namespace Server.Network
{
    [Flags]
    public enum CMEFlags
    {
        None = 0x00,
        Disabled = 0x01,
        Arrow = 0x02,
        Highlighted = 0x04,
        Colored = 0x20
    }

    public static class OutgoingMenuPackets
    {
        public static void SendDisplayItemListMenu(this NetState ns, ItemListMenu menu)
        {
            if (ns == null || menu == null || !ns.GetSendBuffer(out var buffer))
            {
                return;
            }

            var writer = new CircularBufferWriter(buffer);
            writer.Write((byte)0x7C);  // Packet ID
            writer.Seek(2, SeekOrigin.Current); // Length
            writer.Write(menu.Serial);
            writer.Write((ushort)0);

            var question = menu.Question?.Trim();

            if (question == null)
            {
                writer.Write((byte)0);
            }
            else
            {
                var questionLength = question.Length;
                writer.Write((byte)questionLength);
                writer.WriteAscii(question);
            }

            var entries = menu.Entries;

            int entriesLength = (byte)entries.Length;

            writer.Write((byte)entriesLength);

            for (var i = 0; i < entriesLength; ++i)
            {
                var e = entries[i];

                writer.Write((ushort)e.ItemID);
                writer.Write((short)e.Hue);

                var name = e.Name?.Trim();

                if (name == null)
                {
                    writer.Write((byte)0);
                }
                else
                {
                    var nameLength = name.Length;
                    writer.Write((byte)nameLength);
                    writer.WriteAscii(name);
                }
            }

            writer.WritePacketLength();

            ns.Send(ref buffer, writer.Position);
        }

        public static void SendDisplayQuestionMenu(this NetState ns, QuestionMenu menu)
        {
            if (ns == null || menu == null || !ns.GetSendBuffer(out var buffer))
            {
                return;
            }

            var writer = new CircularBufferWriter(buffer);
            writer.Write((byte)0x7C); // Packet ID
            writer.Seek(2, SeekOrigin.Current); // Length
            writer.Write(menu.Serial);
            writer.Write((ushort)0);

            var question = menu.Question?.Trim();

            if (question == null)
            {
                writer.Write((byte)0);
            }
            else
            {
                var questionLength = question.Length;
                writer.Write((byte)questionLength);
                writer.WriteAscii(question);
            }

            var answers = menu.Answers;

            int answersLength = (byte)answers.Length;

            writer.Write((byte)answersLength);

            for (var i = 0; i < answersLength; ++i)
            {
                writer.Write(0);

                var answer = answers[i]?.Trim();

                if (answer == null)
                {
                    writer.Write((byte)0);
                }
                else
                {
                    var nameLength = answer.Length;
                    writer.Write((byte)nameLength);
                    writer.WriteAscii(answer);
                }
            }

            writer.WritePacketLength();

            ns.Send(ref buffer, writer.Position);
        }

        public static void SendDisplayContextMenu(this NetState ns, ContextMenu menu)
        {
            if (ns == null || menu == null || !ns.GetSendBuffer(out var buffer))
            {
                return;
            }

            var newCommand = ns.NewHaven && menu.RequiresNewPacket;

            var entries = menu.Entries;
            var entriesLength = (byte)entries.Length;

            var writer = new CircularBufferWriter(buffer);
            writer.Write((byte)0xBF); // Packet ID
            writer.Seek(2, SeekOrigin.Current); // Length
            writer.Write((short)0x14); // Subpacket
            writer.Write((short)(newCommand ? 0x02 : 0x01)); // Command

            var target = menu.Target;
            writer.Write(target.Serial);
            writer.Write(entriesLength);

            var p = target switch
            {
                Mobile _  => target.Location,
                Item item => item.GetWorldLocation(),
                _         => Point3D.Zero
            };

            for (var i = 0; i < entriesLength; ++i)
            {
                var e = entries[i];

                var range = e.Range;

                if (range == -1)
                {
                    range = Core.GlobalUpdateRange;
                }

                var flags = e.Flags;
                if (!(e.Enabled && menu.From.InRange(p, range)))
                {
                    flags |= CMEFlags.Disabled;
                }

                if (newCommand)
                {
                    writer.Write(e.Number);
                    writer.Write((short)i);
                    writer.Write((short)flags);
                }
                else
                {
                    writer.Write((short)i);
                    writer.Write((ushort)(e.Number - 3000000));

                    var color = e.Color & 0xFFFF;

                    if (color != 0xFFFF)
                    {
                        flags |= CMEFlags.Colored;
                    }

                    writer.Write((short)flags);

                    if ((flags & CMEFlags.Colored) != 0)
                    {
                        writer.Write((short)color);
                    }
                }
            }

            writer.WritePacketLength();

            ns.Send(ref buffer, writer.Position);
        }
    }
}