using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Connections;
using Server.Accounting;
using Server.Gumps;
using Server.HuePickers;
using Server.Items;
using Server.Menus;

namespace Server.Network
{
    public delegate void NetStateCreatedCallback(NetState ns);

    public class AsyncState
    {
        public AsyncState(bool paused) => Paused = paused;
        public bool Paused { get; set; }
    }

    public partial class NetState : IComparable<NetState>
    {
        private static readonly AsyncState m_PauseState = new AsyncState(true);
        private static readonly AsyncState m_ResumeState = new AsyncState(false);

        private static AsyncState m_AsyncState = m_ResumeState;

        private static readonly ConcurrentQueue<NetState> m_Disposed = new ConcurrentQueue<NetState>();
        private readonly string m_ToString;
        internal int m_AuthID;

        private int m_Disposing;

        internal int m_Seed;
        private ClientVersion m_Version;

        public NetState(ConnectionContext connection)
        {
            Connection = connection;
            Seeded = false;
            Gumps = new List<Gump>();
            HuePickers = new List<HuePicker>();
            Menus = new List<IMenu>();
            Trades = new List<SecureTrade>();

            try
            {
                Address = Utility.Intern(((IPEndPoint)Connection.RemoteEndPoint).Address);
                m_ToString = Address.ToString();
            }
            catch (Exception ex)
            {
                TraceException(ex);
                Address = IPAddress.None;
                m_ToString = "(error)";
            }

            ConnectedOn = DateTime.UtcNow;

            connection.ConnectionClosed.Register(
                () =>
                {
                    TcpServer.Instances.Remove(this);
                    Dispose();
                }
            );

            CreatedCallback?.Invoke(this);
        }

        public DateTime ConnectedOn { get; }

        public TimeSpan ConnectedFor => DateTime.UtcNow - ConnectedOn;

        public DateTime ThrottledUntil { get; set; }

        public IPAddress Address { get; }
        public static AsyncState AsyncState => m_AsyncState;

        public IPacketEncoder PacketEncoder { get; set; }

        public static NetStateCreatedCallback CreatedCallback { get; set; }

        public bool SentFirstPacket { get; set; }

        public bool BlockAllPackets { get; set; }

        public List<SecureTrade> Trades { get; }

        public bool Seeded { get; set; }

        public ConnectionContext Connection { get; private set; }

        public bool CompressionEnabled { get; set; }

        public int Sequence { get; set; }

        public List<Gump> Gumps { get; private set; }

        public List<HuePicker> HuePickers { get; private set; }

        public List<IMenu> Menus { get; private set; }

        public static int GumpCap { get; set; } = 512;

        public static int HuePickerCap { get; set; } = 512;

        public static int MenuCap { get; set; } = 512;

        public CityInfo[] CityInfo { get; set; }

        public Mobile Mobile { get; set; }

        public ServerInfo[] ServerInfo { get; set; }

        public IAccount Account { get; set; }

        public bool IsDisposing => m_Disposing != 0;

        public int CompareTo(NetState other) => other == null ? 1 : m_ToString.CompareTo(other.m_ToString);

        public void ValidateAllTrades()
        {
            for (var i = Trades.Count - 1; i >= 0; --i)
            {
                if (i >= Trades.Count)
                {
                    continue;
                }

                var trade = Trades[i];

                if (trade.From.Mobile.Deleted || trade.To.Mobile.Deleted || !trade.From.Mobile.Alive ||
                    !trade.To.Mobile.Alive || !trade.From.Mobile.InRange(trade.To.Mobile, 2) ||
                    trade.From.Mobile.Map != trade.To.Mobile.Map)
                {
                    trade.Cancel();
                }
            }
        }

        public void CancelAllTrades()
        {
            for (var i = Trades.Count - 1; i >= 0; --i)
            {
                if (i < Trades.Count)
                {
                    Trades[i].Cancel();
                }
            }
        }

        public void RemoveTrade(SecureTrade trade)
        {
            Trades.Remove(trade);
        }

        public SecureTrade FindTrade(Mobile m)
        {
            for (var i = 0; i < Trades.Count; ++i)
            {
                var trade = Trades[i];

                if (trade.From.Mobile == m || trade.To.Mobile == m)
                {
                    return trade;
                }
            }

            return null;
        }

        public SecureTradeContainer FindTradeContainer(Mobile m)
        {
            for (var i = 0; i < Trades.Count; ++i)
            {
                var trade = Trades[i];

                var from = trade.From;
                var to = trade.To;

                if (from.Mobile == Mobile && to.Mobile == m)
                {
                    return from.Container;
                }

                if (from.Mobile == m && to.Mobile == Mobile)
                {
                    return to.Container;
                }
            }

            return null;
        }

        public SecureTradeContainer AddTrade(NetState state)
        {
            var newTrade = new SecureTrade(Mobile, state.Mobile);

            Trades.Add(newTrade);
            state.Trades.Add(newTrade);

            return newTrade.From.Container;
        }

        public void WriteConsole(string text)
        {
            Console.WriteLine("Client: {0}: {1}", this, text);
        }

        public void WriteConsole(string format, params object[] args)
        {
            WriteConsole(string.Format(format, args));
        }

        public void AddMenu(IMenu menu)
        {
            Menus ??= new List<IMenu>();

            if (Menus.Count < MenuCap)
            {
                Menus.Add(menu);
            }
            else
            {
                WriteConsole("Exceeded menu cap, disconnecting...");
                Dispose();
            }
        }

        public void RemoveMenu(IMenu menu)
        {
            Menus?.Remove(menu);
        }

        public void RemoveMenu(int index)
        {
            Menus?.RemoveAt(index);
        }

        public void ClearMenus()
        {
            Menus?.Clear();
        }

        public void AddHuePicker(HuePicker huePicker)
        {
            HuePickers ??= new List<HuePicker>();

            if (HuePickers.Count < HuePickerCap)
            {
                HuePickers.Add(huePicker);
            }
            else
            {
                WriteConsole("Exceeded hue picker cap, disconnecting...");
                Dispose();
            }
        }

        public void RemoveHuePicker(HuePicker huePicker)
        {
            HuePickers?.Remove(huePicker);
        }

        public void RemoveHuePicker(int index)
        {
            HuePickers?.RemoveAt(index);
        }

        public void ClearHuePickers()
        {
            HuePickers?.Clear();
        }

        public void AddGump(Gump gump)
        {
            Gumps ??= new List<Gump>();

            if (Gumps.Count < GumpCap)
            {
                Gumps.Add(gump);
            }
            else
            {
                WriteConsole("Exceeded gump cap, disconnecting...");
                Dispose();
            }
        }

        public void RemoveGump(Gump gump)
        {
            Gumps?.Remove(gump);
        }

        public void RemoveGump(int index)
        {
            Gumps?.RemoveAt(index);
        }

        public void ClearGumps()
        {
            Gumps?.Clear();
        }

        public void LaunchBrowser(string url)
        {
            Send(new MessageLocalized(Serial.MinusOne, -1, MessageType.Label, 0x35, 3, 501231, "", ""));
            Send(new LaunchBrowser(url));
        }

        public override string ToString() => m_ToString;

        public static void Pause()
        {
            m_AsyncState = Interlocked.Exchange(ref m_AsyncState, m_PauseState);
        }

        public static void Resume()
        {
            m_AsyncState = Interlocked.Exchange(ref m_AsyncState, m_ResumeState);
        }

        public virtual async void Send(Packet p)
        {
            if (Connection == null || BlockAllPackets)
            {
                p.OnSend();
                return;
            }

            var outPipe = Connection.Transport.Output;

            try
            {
                // TODO: Rented memory
                ReadOnlyMemory<byte> buffer = p.Compile(CompressionEnabled, out var length);

                if (buffer.Length > 0 && length > 0)
                {
                    var result = await outPipe.WriteAsync(buffer.Slice(0, length));

                    if (result.IsCanceled || result.IsCompleted)
                    {
                        Dispose();
                        return;
                    }
                }

                p.OnSend();
            }
            catch (SocketException ex)
            {
                Console.WriteLine(ex);
                TraceException(ex);
                Dispose();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
                Dispose();
            }
        }

        public async Task ProcessIncoming(IMessagePumpService messagePumpService)
        {
            var inPipe = Connection.Transport.Input;

            try
            {
                while (true)
                {
                    if (AsyncState.Paused)
                    {
                        continue;
                    }

                    var result = await inPipe.ReadAsync();
                    if (result.IsCanceled || result.IsCompleted)
                    {
                        return;
                    }

                    var seq = result.Buffer;

                    if (seq.IsEmpty)
                    {
                        break;
                    }

                    var pos = PacketHandlers.ProcessPacket(messagePumpService, this, seq);

                    if (pos <= 0)
                    {
                        break;
                    }

                    inPipe.AdvanceTo(seq.Slice(0, pos).End);
                }
            }
            catch (SocketException ex)
            {
                Console.WriteLine(ex);
                TraceException(ex);
            }
            catch
            {
                // Console.WriteLine(ex);
            }
            finally
            {
                Dispose();
            }
        }

        public bool CheckEncrypted(int packetID)
        {
            if (!SentFirstPacket && packetID != 0xF0 && packetID != 0xF1 && packetID != 0xCF && packetID != 0x80 &&
                packetID != 0x91 && packetID != 0xA4 && packetID != 0xEF)
            {
                Console.WriteLine("Client: {0}: Encrypted client detected, disconnecting", this);
                Dispose();
                return true;
            }

            return false;
        }

        public PacketHandler GetHandler(int packetID) =>
            ContainerGridLines ? PacketHandlers.Get6017Handler(packetID) : PacketHandlers.GetHandler(packetID);

        public static void TraceException(Exception ex)
        {
            try
            {
                using var op = new StreamWriter("network-errors.log", true);
                op.WriteLine("# {0}", DateTime.UtcNow);

                op.WriteLine(ex);

                op.WriteLine();
                op.WriteLine();
            }
            catch
            {
                // ignored
            }

            Console.WriteLine(ex);
        }

        public virtual void Dispose()
        {
            var disposing = Interlocked.Exchange(ref m_Disposing, 1);
            if (disposing == 1)
            {
                return;
            }

            try
            {
                Connection.Transport.Input.Complete();
                Connection.Transport.Output.Complete();
                Connection.Abort();
                Task.Run(Connection.DisposeAsync).Wait();
            }
            catch (Exception ex)
            {
                TraceException(ex);
            }

            Connection = null;
            m_Disposed.Enqueue(this);
        }

        public static void ProcessDisposedQueue()
        {
            var breakout = 0;

            while (breakout++ < 200)
            {
                if (!m_Disposed.TryDequeue(out var ns))
                {
                    break;
                }

                var m = ns.Mobile;
                var a = ns.Account;

                if (m != null)
                {
                    m.NetState = null;
                    ns.Mobile = null;
                }

                ns.Gumps.Clear();
                ns.Menus.Clear();
                ns.HuePickers.Clear();
                ns.Account = null;
                ns.ServerInfo = null;
                ns.CityInfo = null;

                if (a != null)
                {
                    ns.WriteConsole("Disconnected. [{0} Online] [{1}]", TcpServer.Instances.Count, a);
                }
                else
                {
                    ns.WriteConsole("Disconnected. [{0} Online]", TcpServer.Instances.Count);
                }
            }
        }
    }
}