using System.Collections.Generic;
using UnityEngine;
using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace NeonTea.Quakeball.Net.Peers {
    public abstract class Peer {
        private Thread ListenThread;

        public byte[] Fingerprint = new byte[] { 0xCA, 0x11, 0x7F, 0xF8 };

        protected UdpClient UdpClient;
        protected Connection MainConnection;

        public abstract void OnStart(string orighost, int origport);
        public abstract void OnStop(DisconnectReason reason);
        public abstract void HandlePacket(IPEndPoint endpoint, ByteReader reader);

        public void Start(string host, int port) {
            int own_port = port;
            if (this.GetType() == typeof(Client)) {
                own_port = 0;
            }
            UdpClient = new UdpClient(own_port);

            try {
                MainConnection = new Connection(new IPEndPoint(FindAddress(host), port));
            } catch (Exception e) {
                Debug.Log($"Failed to create initial connection: {e.ToString()}");
                Net.Singleton.Stop(new DisconnectReason(Reason.INITIAL_ERROR, e.ToString()));
                return;
            }
            StartListen(MainConnection);

            OnStart(host, port);
        }

        public void Stop(DisconnectReason reason) {
            UdpClient.Close();
            if (ListenThread != null) {
                ListenThread.Abort();
            }
            MainConnection.Status = ConnectionStatus.Closed;
            OnStop(reason);
        }

        protected IPAddress FindAddress(string host) {
            IPAddress addr;
            try {
                addr = Dns.GetHostAddresses(host)[0];
            } catch (ArgumentException) {
                addr = IPAddress.Parse(host);
            }
            return addr;
        }

        protected void SendBytes(byte[] bytes, IPEndPoint endpoint) {
            if (bytes != null) {
                List<byte> ByteList = new List<byte>();
                ByteList.AddRange(Fingerprint);
                ByteList.AddRange(bytes);
                byte[] sent = ByteList.ToArray();
                UdpClient.Send(sent, sent.Length, endpoint);
            }
        }

        private bool StartListen(Connection connection) {
            if (ListenThread != null) {
                return false;
            }
            Thread t = new Thread(ListenThreadMethod);
            t.Start(connection);
            ListenThread = t;
            return true;
        }

        private void ListenThreadMethod(object obj) {
            Connection listened;
            try {
                listened = (Connection)obj;
            } catch (InvalidCastException) {
                Debug.Log($"Can not cast {obj} to a Connection");
                return;
            }
            while (listened.Status != ConnectionStatus.Closed) {
                try {
                    IPEndPoint Listened = new IPEndPoint(listened.Endpoint.Address, listened.Endpoint.Port);
                    ByteReader Received = new ByteReader(UdpClient.Receive(ref Listened));
                    foreach (byte b in Fingerprint) {
                        if (!(Received.hasNext() && Received.next() == b)) {
                            goto end_of_handle;
                        }
                    }
                    HandlePacket(Listened, Received);
                } catch (Exception e) {
                    Net.Singleton.Stop(new DisconnectReason(Reason.LISTENING_ERROR, e.ToString()));
                }
            end_of_handle: { };
            }
        }
    }

    public class ByteReader {
        private byte[] ByteList;
        private uint pos = 0;

        public ByteReader(byte[] list) {
            ByteList = list;
        }

        public bool hasNext() {
            return pos < ByteList.Length;
        }

        public byte next() {
            return ByteList[pos++];
        }
    }

    public struct DisconnectReason {
        public static DisconnectReason LOCAL_MANUAL = new DisconnectReason(Reason.LOCAL_MANUAL, "");

        public Reason Reason;
        public string Description;

        public DisconnectReason(Reason reason, string description) {
            Reason = reason;
            Description = description;
        }
    }

    public enum Reason {
        LOCAL_MANUAL,
        LISTENING_ERROR,
        INITIAL_ERROR,
    }
}