using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Numerics;
using System.Threading;
using System.Threading.Tasks;
using Mistox.ResevedPackets;

namespace Mistox.Client {

    public class MistoxClient {

        public string ServerName { get; private set; } = "";                        // The Name of the server
        public string UserName { get; private set; } = "";                          // My UserName
        public bool Alive { get; set; } = true;                                     // Is the server running
        public bool isAuthenticated { get; private set; } = false;                  // Is the server authenticated
        public ConcurrentDictionary<IPEndPoint, mUDPClient> clientConnections { get; private set; } = new();    // UserName, Connection
        public Vector3 Position { get; set; } = new Vector3(0, 0, 0);               // My world position
        public float MaxNetworkRenderDistance { get; private set; } = 0;            // The distance for connections

        public mTCPClient? ServerConnection {get; private set; }                     // Global TCP Server Connection
        public UdpClient ClientSocket { get; private set; }                         // Global UDP Sender
        public UDPReceiver UdpReceiver { get; private set; }                        // Global UDP Receiver

        private readonly string ConnectionKey = "";                                 // Server Connection Key
        private readonly int Port = 0;                                              // The port of the connected socket
        private readonly int HeartbeatInterval = 5000;                              // How often should we heartbeat

        public MistoxClient(string userName, string connectionKey, IPEndPoint Server) {
            // Create and listen on UDP
            Port = Server.Port;
            ClientSocket = new UdpClient( Server.Port );
            UdpReceiver = new UDPReceiver( this );
            UserName = userName;
            ConnectionKey = connectionKey;

            onServerConnected += () => {};
            onUserConnected += (_) => {};
            onUserJoined += (_) => {};
            onDataReceived += (_,_) => {};
            onUserLeft += (_) => {};
            onUserDisconnected += (_) => {};
            onServerDisconnected += () => {};

            // Create and connect to server on TCP
            Console.WriteLine( "The client is initilized and trying to connect to the server at ip : " + Server.Address );
            try {
                ServerConnection = new mTCPClient( this, Server );
                Console.WriteLine( "Connected to the server sucessfully" );
                Alive = true;
            } catch ( Exception e ) {
                Console.WriteLine( "An error has occured with the connection to the server. Error { " );
                Console.WriteLine( e.ToString() );
                Console.WriteLine( "}" );
                Alive = false;
            }

            // Start the heartbeat
            _ = RunAsync(Heartbeat);
        }

        async Task RunAsync(Func<Task> work) {
            try{
                await work();
            } catch (Exception ex) {
                Console.WriteLine($"Error during background packet processing: {ex.Message}");
            }
        }

/////////////////////////////
// Heartbeat
/////////////////////////////

        async Task Heartbeat() {
            while (Alive) {
                await SendServer(new HeartbeatPacket {
                    Position = Position
                });
                Thread.Sleep(HeartbeatInterval);
            }
        }

        void HeartbeatReceived(HeartbeatPacket packet) {
            // Build a HashSet of server IP addresses for O(1) removal checks
            var activeIps = new HashSet<IPAddress>(packet.ServerList.Count);
            for (int i = 0; i < packet.ServerList.Count; i++) {
                activeIps.Add(packet.ServerList[i].IpAddress);
            }

            // Add users that joined
            foreach (UserTableObject cur in packet.ServerList) {
                IPEndPoint remoteHost = new IPEndPoint(cur.IpAddress, Port);
                if (!clientConnections.ContainsKey(remoteHost)) {
                    mUDPClient newConnection = new mUDPClient(this, remoteHost);
                    clientConnections[remoteHost] = newConnection;
                }
            }

            // Remove users that left
            foreach (IPEndPoint key in clientConnections.Keys) {
                if (!activeIps.Contains(key.Address)) {
                    clientConnections.TryRemove(key, out _);
                }
            }
            
            // Update distance status
            float maxDistanceSq = MaxNetworkRenderDistance * MaxNetworkRenderDistance;
            foreach (mUDPClient cur in clientConnections.Values) {
                float dx = Position.X - cur.Position.X;
                float dy = Position.Y - cur.Position.Y;
                float dz = Position.Z - cur.Position.Z;
                
                // Fixed bug (dz * dz instead of dz + dz) & avoided Sqrt
                float distanceSq = (dx * dx) + (dy * dy) + (dz * dz);
                cur.WithinRange = distanceSq < maxDistanceSq;
            }
        }

/////////////////////////////
// Auth
/////////////////////////////

        async Task TryAuth() {
            Console.WriteLine("Attempting to authenticate against the server...");
            if (ServerConnection == null) return;
            await ServerConnection.Send(new UserAuthPacket {
                UserName = UserName,
                ConnectionKey = ConnectionKey
            });
        }

        async Task CheckAuthStatus(UserAuthPacket packet) {
            if (packet.AuthSuccessful == 1) {
                isAuthenticated = true;
            }
            ServerName = packet.ServerName;
        }

/////////////////////////////
// Events
/////////////////////////////

        // When (self) connects to the server
        public event Action onServerConnected;
        public void InvokeOnServerConnected(){
            Alive = true;
            Task.Run(async () => {
                try {
                    await TryAuth();
                } catch {}
            });
            onServerConnected?.Invoke();
        }

        // When any user connects to the server (self) hasn't seen yet
        public event Action<string> onUserJoined;
        public void InvokeOnUserJoined(string UserName){
            onUserJoined?.Invoke(UserName);
        }

        // When user is within range of (self) and network rendering starts
        public event Action<mUDPClient> onUserConnected;
        public void InvokeOnUserConnected(mUDPClient ConnectedUser){
            onUserConnected?.Invoke(ConnectedUser);
        }

        // When generic data is received
        public event Action<mUDPClient?, dynamic> onDataReceived;
        public void InvokeOnReceived(dynamic DataPacket, mUDPClient? remote = null){
            switch (DataPacket as object)  {
                case HeartbeatPacket packet:
                    HeartbeatReceived(packet); 
                    break;
                case UserAuthPacket packet:
                    _ = RunAsync(async () => {
                        await CheckAuthStatus(packet);
                    });
                    break;
                case null:
                    Console.WriteLine("Received a null packet.");
                    break;
                default:
                    onDataReceived?.Invoke(remote, DataPacket);
                    break;
            }
        }

        // When user is no longer in range of (self) and network rendering stops
        public event Action<mUDPClient> onUserDisconnected;
        public void InvokeOnUserDisconnected(mUDPClient DisconnectedUser){
            onUserDisconnected?.Invoke(DisconnectedUser);
        }

        // When any user disconnects from the server that isn't (self)
        public event Action<string> onUserLeft;
        public void InvokeOnUserLeft(string UserName){
            onUserLeft?.Invoke(UserName);
        }

        // When (self) disconnects to the server
        public event Action onServerDisconnected;
        public void InvokeOnServerDisconnected(){
            Alive = false;
            onServerDisconnected?.Invoke();
        }

/////////////////////////////
// Send Methods
/////////////////////////////

        public async Task SendAllClientsInRange<Packet>(Packet data) {
            foreach( mUDPClient cur in clientConnections.Values ){
                if (cur.WithinRange) {
                    await cur.Send( data );
                }
            }
        }

        public async Task SendClient<Packet>(string UserName, Packet data) {
            foreach( mUDPClient cur in clientConnections.Values ) {
                if (cur.UserName.ToLower() == UserName.ToLower()) {
                    await cur.Send( data );
                    break;
                }
            }
        }

        public async Task SendServer<Packet>(Packet data) {
            if (ServerConnection == null) return;
            await ServerConnection.Send( data );
        }
    }

}