using LobbyRelaySample;
using System;
using System.Collections;
using Unity.Collections;
using Unity.Jobs;
using Unity.Networking.Transport;
using Unity.Networking.Transport.Relay;
using Unity.Services.Relay;
using Unity.Services.Relay.Allocations;
using Unity.Services.Relay.Models;
using UnityEngine;

namespace LobbyRelaySample.Relay
{
    /// <summary>
    /// Responsible for setting up a connection with Relay using UTP, for the lobby host.
    /// Must be a MonoBehaviour since the binding process doesn't have asynchronous callback options.
    /// </summary>
    public abstract class RelayUTPSetup : MonoBehaviour
    {
        protected bool m_isRelayConnected = false;
        protected NetworkDriver m_networkDriver;
        protected NativeList<NetworkConnection> m_connections;
        protected NetworkEndPoint m_endpointForServer;
        protected JobHandle m_currentUpdateHandle;

        protected void BindToAllocation(string ip, int port, byte[] allocationIdBytes, byte[] connectionDataBytes, byte[] hostConnectionDataBytes, byte[] hmacKeyBytes, int connectionCapacity)
        {
            NetworkEndPoint     serverEndpoint     = NetworkEndPoint.Parse(ip, (ushort)port);
            RelayAllocationId   allocationId       = ConvertAllocationIdBytes(allocationIdBytes);
            RelayConnectionData connectionData     = ConvertConnectionDataBytes(connectionDataBytes);
            RelayConnectionData hostConnectionData = ConvertConnectionDataBytes(hostConnectionDataBytes);
            RelayHMACKey        key                = ConvertHMACKeyBytes(hmacKeyBytes);

            m_endpointForServer = serverEndpoint;
            var relayServerData = new RelayServerData(ref serverEndpoint, 0, ref allocationId, ref connectionData, ref hostConnectionData, ref key);
            relayServerData.ComputeNewNonce();
            var relayNetworkParameter = new RelayNetworkParameter { ServerData = relayServerData };

            m_networkDriver = NetworkDriver.Create(new INetworkParameter[] { relayNetworkParameter });
            m_connections = new NativeList<NetworkConnection>(connectionCapacity, Allocator.Persistent);

            if (m_networkDriver.Bind(NetworkEndPoint.AnyIpv4) != 0)
                Debug.LogError("Failed to bind to Relay allocation.");
            else
                StartCoroutine(WaitForBindComplete()); // TODO: This is the only reason for being a MonoBehaviour?
        }

        private IEnumerator WaitForBindComplete()
        {
            while (!m_networkDriver.Bound)
            {
                m_networkDriver.ScheduleUpdate().Complete();
                yield return null; // TODO: Does this not proceed until a client connects as well?
            }
            OnBindingComplete();
        }

        protected abstract void OnBindingComplete();

        #region UTP uses pointers instead of managed arrays for performance reasons, so we use these helper functions to convert them.
        unsafe private static RelayAllocationId ConvertAllocationIdBytes(byte[] allocationIdBytes)
        {
            fixed (byte* ptr = allocationIdBytes)
            {
                return RelayAllocationId.FromBytePointer(ptr, allocationIdBytes.Length);
            }
        }

        unsafe private static RelayConnectionData ConvertConnectionDataBytes(byte[] connectionData)
        {
            fixed (byte* ptr = connectionData)
            {
                return RelayConnectionData.FromBytePointer(ptr, RelayConnectionData.k_Length);
            }
        }

        unsafe private static RelayHMACKey ConvertHMACKeyBytes(byte[] hmac)
        {
            fixed (byte* ptr = hmac)
            {
                return RelayHMACKey.FromBytePointer(ptr, RelayHMACKey.k_Length);
            }
        }
        #endregion


        private void LateUpdate()
        {
            if (m_networkDriver.IsCreated && m_isRelayConnected)
                m_currentUpdateHandle.Complete(); // This prevents warnings about a job allocation longer than 4 frames if FixedUpdate is very fast.
        }
    }

    public class RelayUtpSetup_Host : RelayUTPSetup
    {
        private LocalLobby m_localLobby;

        public void DoRelaySetup(LocalLobby localLobby)
        {
            m_localLobby = localLobby;
            RelayInterface.AllocateAsync(m_localLobby.MaxPlayerCount, OnAllocation);
        }

        public void OnAllocation(Allocation allocation)
        {
            RelayInterface.GetJoinCodeAsync(allocation.AllocationId, OnRelayCode);
            BindToAllocation(allocation);
        }

        public void OnRelayCode(string relayCode)
        {
            m_localLobby.RelayCode = relayCode;
            RelayInterface.JoinAsync(m_localLobby.RelayCode, OnJoin);
        }

        private void OnJoin(JoinAllocation joinAllocation)
        {
            m_localLobby.RelayServer = new ServerAddress(joinAllocation.RelayServer.IpV4, joinAllocation.RelayServer.Port);
        }

        private void BindToAllocation(Allocation allocation)
        {
            BindToAllocation(allocation.RelayServer.IpV4, allocation.RelayServer.Port, allocation.AllocationIdBytes, allocation.ConnectionData, allocation.ConnectionData, allocation.Key, 16);
        }

        protected override void OnBindingComplete()
        {
            if (m_networkDriver.Listen() != 0)
            {
                Debug.LogError("Server failed to listen");
            }
            else
            {
                Debug.LogWarning("Server is now listening!");
                m_isRelayConnected = true;
            }
        }

        struct DriverUpdateJob : IJob
        {
            public NetworkDriver driver;
            public NativeList<NetworkConnection> connections;

            public void Execute()
            {
                // Remove connections which have been destroyed from the list of active connections
                for (int i = 0; i < connections.Length; ++i)
                {
                    if (!connections[i].IsCreated)
                    {
                        connections.RemoveAtSwapBack(i);
                        // Index i is a new connection since we did a swap back, check it again
                        --i;
                    }
                }

                // Accept all new connections
                while (true)
                {
                    var con = driver.Accept();
                    // "Nothing more to accept" is signaled by returning an invalid connection from accept
                    if (!con.IsCreated)
                        break;
                    connections.Add(con);
                }
            }
        }

        private struct PongJob : Unity.Jobs.IJobParallelForDefer
        {
            public NetworkDriver.Concurrent driver;
            public NativeArray<NetworkConnection> connections;

            public void Execute(int i)
            {
                DataStreamReader strm;
                NetworkEvent.Type cmd;
                // Pop all events for the connection
                while ((cmd = driver.PopEventForConnection(connections[i], out strm)) != NetworkEvent.Type.Empty)
                {
                    if (cmd == NetworkEvent.Type.Data)
                    {
                        // For ping requests we reply with a pong message
                        int id = strm.ReadInt();

                        Debug.LogWarning("Received int: " + id);

                        // Create a temporary DataStreamWriter to keep our serialized pong message
                        if (driver.BeginSend(connections[i], out var pongData) == 0)
                        {
                            pongData.WriteInt(id);
                            // Send the pong message with the same id as the ping
                            driver.EndSend(pongData);
                        }
                    }
                    else if (cmd == NetworkEvent.Type.Disconnect)
                    {
                        // When disconnected we make sure the connection return false to IsCreated so the next frames
                        // DriverUpdateJob will remove it
                        connections[i] = default(NetworkConnection);
                    }
                }
            }
        }

        private void Update()
        {
            // When connecting to the relay we need to this? 
            if (m_networkDriver.IsCreated && !m_isRelayConnected)
            {
                m_networkDriver.ScheduleUpdate().Complete();
            
                var updateJob = new DriverUpdateJob {driver = m_networkDriver, connections = m_connections};
                updateJob.Schedule().Complete();
            }
        }

        void FixedUpdate()
        {
            if (m_networkDriver.IsCreated && m_isRelayConnected) {
                // Wait for the previous frames ping to complete before starting a new one, the Complete in LateUpdate is not
                // enough since we can get multiple FixedUpdate per frame on slow clients
                m_currentUpdateHandle.Complete();
                var updateJob = new DriverUpdateJob {driver = m_networkDriver, connections = m_connections};
                var pongJob = new PongJob
                {
                    // PongJob is a ParallelFor job, it must use the concurrent NetworkDriver
                    driver = m_networkDriver.ToConcurrent(),
                    // PongJob uses IJobParallelForDeferExtensions, we *must* use AsDeferredJobArray in order to access the
                    // list from the job
                    connections = m_connections.AsDeferredJobArray()
                };
                // Update the driver should be the first job in the chain
                m_currentUpdateHandle = m_networkDriver.ScheduleUpdate();
                // The DriverUpdateJob which accepts new connections should be the second job in the chain, it needs to depend
                // on the driver update job
                m_currentUpdateHandle = updateJob.Schedule(m_currentUpdateHandle);
                // PongJob uses IJobParallelForDeferExtensions, we *must* schedule with a list as first parameter rather than
                // an int since the job needs to pick up new connections from DriverUpdateJob
                // The PongJob is the last job in the chain and it must depends on the DriverUpdateJob
                m_currentUpdateHandle = pongJob.Schedule(m_connections, 1, m_currentUpdateHandle);
            }
        }
    }

    public class RelayUtpSetup_Client : RelayUTPSetup
    {
        private LocalLobby m_localLobby;
        private JobHandle m_activeUpdateJobHandle;

        public void JoinRelay(LocalLobby localLobby)
        {
            m_localLobby = localLobby;
            localLobby.onChanged += OnLobbyChange;
        }

        private void OnLobbyChange(LocalLobby lobby)
        {
            if (m_localLobby.RelayCode != null)
            {
                RelayInterface.JoinAsync(m_localLobby.RelayCode, OnJoin);
                m_localLobby.onChanged -= OnLobbyChange;
            }
        }

        private void OnJoin(JoinAllocation allocation)
        {
            if (allocation == null)
                return; // TODO: Error messaging.

            BindToAllocation(allocation.RelayServer.IpV4, allocation.RelayServer.Port, allocation.AllocationIdBytes, allocation.ConnectionData, allocation.HostConnectionData, allocation.Key, 1);
        }

        protected override void OnBindingComplete()
        {
            StartCoroutine(ConnectToServer());
        }

        private IEnumerator ConnectToServer()
        {
            // Once the client is bound to the Relay server, you can send a connection request
            m_connections.Add(m_networkDriver.Connect(m_endpointForServer));
            while (m_networkDriver.GetConnectionState(m_connections[0]) == NetworkConnection.State.Connecting)
            {
                m_networkDriver.ScheduleUpdate().Complete();
                yield return null;
            }
            if (m_networkDriver.GetConnectionState(m_connections[0]) != NetworkConnection.State.Connected)
                Debug.LogError("Client failed to connect to server");
        }

        private struct PingJob : IJob
        {
            public NetworkDriver driver;
            public NativeArray<NetworkConnection> connection; // TODO: I think we were using NativeArray to merely contain one entry, since we'd be unable to pass just that via jobs?
            public float fixedTime;

            public void Execute()
            {
                DataStreamReader strm;
                NetworkEvent.Type cmd;
                // Process all events on the connection. If the connection is invalid it will return Empty immediately
                while (connection.Length > 0 && (cmd = connection[0].PopEvent(driver, out strm)) != NetworkEvent.Type.Empty)
                {
                    if (cmd == NetworkEvent.Type.Connect)
                    {
                        // Create a 4 byte data stream which we can store our ping sequence number in

                        if (driver.BeginSend(connection[0], out var pingData) == 0)
                        {
                            pingData.WriteInt(123);
                            driver.EndSend(pingData);
                        }
                    }
                    else if (cmd == NetworkEvent.Type.Data)
                    {
                        //// When the pong message is received we calculate the ping time and disconnect
                        //pingStats[1] = (int)((fixedTime - pendingPings[0].time) * 1000);
                        //connection[0].Disconnect(driver);
                        //connection[0] = default(NetworkConnection);
                        if (driver.BeginSend(connection[0], out var pingData) == 0)
                        {
                            pingData.WriteInt(1234);
                            driver.EndSend(pingData);
                        }
                    }
                    else if (cmd == NetworkEvent.Type.Disconnect)
                    {
                        // If the server disconnected us we clear out connection
                        connection[0] = default(NetworkConnection);
                    }
                }
            }
        }

        private void Update()
        {
            // When connecting to the relay we need to this? 
            if (m_networkDriver.IsCreated && !m_isRelayConnected)
            {
                m_networkDriver.ScheduleUpdate().Complete();

                var pingJob = new PingJob
                {
                    driver = m_networkDriver,
                    connection = m_connections.AsArray(),
                    fixedTime = Time.fixedTime
                };

                pingJob.Schedule().Complete();
            }
        }

        void FixedUpdate()
        {
            if (m_networkDriver.IsCreated && m_isRelayConnected)
            {

                // Wait for the previous frames ping to complete before starting a new one, the Complete in LateUpdate is not
                // enough since we can get multiple FixedUpdate per frame on slow clients
                m_activeUpdateJobHandle.Complete();

                var pingJob = new PingJob
                {
                    driver = m_networkDriver,
                    connection = m_connections,
                    fixedTime = Time.fixedTime
                };
                // Schedule a chain with the driver update followed by the ping job
                m_activeUpdateJobHandle = m_networkDriver.ScheduleUpdate();
                m_activeUpdateJobHandle = pingJob.Schedule(m_activeUpdateJobHandle);
            }
        }
    }
}