using Steamworks;
using Steamworks.Data;
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using UnityEngine;

namespace Mirror.FizzySteam
{
    public class NextClient : NextCommon, IClient
    {
        public bool Connected { get; private set; }
        public bool Error { get; private set; }

        private TimeSpan ConnectionTimeout;

        private event Action<byte[], int> OnReceivedData;
        private event Action OnConnected;
        private event Action OnDisconnected;
        private Action<string> SetTransportError;

        private CancellationTokenSource cancelToken;
        private TaskCompletionSource<Task> connectedComplete;
        private SteamId hostSteamID = 0;
        private FizzyConnectionManager HostConnectionManager;
        private Connection HostConnection => HostConnectionManager.Connection;
        private List<Action> BufferedData;

        private NextClient(FizzyFacepunch transport)
        {
            ConnectionTimeout = TimeSpan.FromSeconds(Math.Max(1, transport.Timeout));
            BufferedData = new List<Action>();
        }

        public static NextClient CreateClient(FizzyFacepunch transport, string host)
        {
            NextClient c = new NextClient(transport);

            c.OnConnected += () => transport.OnClientConnected.Invoke();
            c.OnDisconnected += () => transport.OnClientDisconnected.Invoke();
            c.OnReceivedData += (data, ch) => transport.OnClientDataReceived.Invoke(new ArraySegment<byte>(data), ch);
            c.SetTransportError = transport.SetTransportError;

            if (SteamClient.IsValid)
            {
                c.Connect(host);
            }
            else
            {
                c.SetTransportError("SteamWorks not initialized");
                Debug.LogError("SteamWorks not initialized");
                c.OnConnectionFailed();
            }

            return c;
        }

        private async void Connect(string host)
        {
            cancelToken = new CancellationTokenSource();
            SteamNetworkingSockets.OnConnectionStatusChanged += OnConnectionStatusChanged;

            try
            {
                hostSteamID = UInt64.Parse(host);
                connectedComplete = new TaskCompletionSource<Task>();
                OnConnected += SetConnectedComplete;
                HostConnectionManager = SteamNetworkingSockets.ConnectRelay<FizzyConnectionManager>(hostSteamID);
                HostConnectionManager.ForwardMessage = OnMessageReceived;
                Task connectedCompleteTask = connectedComplete.Task;
                Task timeOutTask = Task.Delay(ConnectionTimeout, cancelToken.Token);

                if (await Task.WhenAny(connectedCompleteTask, timeOutTask) != connectedCompleteTask)
                {
                    if (cancelToken.IsCancellationRequested)
                    {
                        SetTransportError("The connection attempt was cancelled.");
                        Debug.LogError($"The connection attempt was cancelled.");
                    }
                    else if (timeOutTask.IsCompleted)
                    {
                        SetTransportError($"Connection to {host} timed out.");
                        Debug.LogError($"Connection to {host} timed out.");
                    }

                    OnConnected -= SetConnectedComplete;
                    OnConnectionFailed();
                }

                OnConnected -= SetConnectedComplete;
            }
            catch (FormatException)
            {
                SetTransportError("Connection string was not in the right format. Did you enter a SteamId?");
                Debug.LogError($"Connection string was not in the right format. Did you enter a SteamId?");
                Error = true;
                OnConnectionFailed();
            }
            catch (Exception ex)
            {
                SetTransportError(ex.Message);
                Debug.LogError(ex.Message);
                Error = true;
                OnConnectionFailed();
            }
            finally
            {
                if (Error)
                {
                    Debug.LogError("Connection failed.");
                    OnConnectionFailed();
                }
            }
        }

        private void OnMessageReceived(IntPtr dataPtr, int size)
        {
            (byte[] data, int ch) = ProcessMessage(dataPtr, size);
            if (Connected)
            {
                OnReceivedData(data, ch);
            }
            else
            {
                BufferedData.Add(() => OnReceivedData(data, ch));
            }
        }

        private void OnConnectionStatusChanged(Connection conn, ConnectionInfo info)
        {
            ulong clientSteamID = info.Identity.SteamId;
            if (info.State == ConnectionState.Connected)
            {
                Connected = true;
                OnConnected.Invoke();
                Debug.LogError("Connection established.");

                if (BufferedData.Count > 0)
                {
                    Debug.LogError($"{BufferedData.Count} received before connection was established. Processing now.");
                    {
                        foreach (Action a in BufferedData)
                        {
                            a();
                        }
                    }
                }
            }
            else if (info.State == ConnectionState.ClosedByPeer)
            {
                SetTransportError("connection closed by peer");
                Connected = false;
                OnDisconnected.Invoke();
                Debug.LogError("Disconnected.");
                conn.Close(false, 0, "Disconnected");
            }
            else
            {
                Debug.LogError($"Connection state changed: {info.State.ToString()}");
            }
        }

        public void Disconnect()
        {
            cancelToken?.Cancel();
            SteamNetworkingSockets.OnConnectionStatusChanged -= OnConnectionStatusChanged;

            if (HostConnectionManager != null)
            {
                Debug.LogError("Sending Disconnect message");
                HostConnection.Close(false, 0, "Graceful disconnect");
                HostConnectionManager = null;
            }
        }

        public void ReceiveData()
        {
            HostConnectionManager.Receive(MAX_MESSAGES);
        }

        public void Send(byte[] data, int channelId)
        {
            Result res = SendSocket(HostConnection, data, channelId);

            if (res != Result.OK)
            {
                Debug.LogError($"Could not send: {res.ToString()}");
            }
        }

        private void SetConnectedComplete() => connectedComplete.SetResult(connectedComplete.Task);
        private void OnConnectionFailed() => OnDisconnected.Invoke();
        public void FlushData()
        {
            HostConnection.Flush();
        }
    }
}