/*
 * Copyright 2023 Eduard Kargin <kargin.eduard@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using ENet;
using NLog;
using Ragon.Protocol;
using Ragon.Server.IO;

namespace Ragon.Server.ENetServer
{
  public sealed class ENetServer : INetworkServer
  {
    public Executor Executor => _executor;

    private readonly Host _host = new();
    private readonly ILogger _logger = LogManager.GetCurrentClassLogger();

    private ENetConnection[] _connections = Array.Empty<ENetConnection>();
    private INetworkListener _listener;
    private uint _protocol;
    private ENet.Event _event;
    private Executor _executor = new();

    public void Start(INetworkListener listener, NetworkConfiguration configuration)
    {
      Library.Initialize();

      _connections = new ENetConnection[configuration.LimitConnections];

      _listener = listener;
      _protocol = configuration.Protocol;

      var address = new Address
      {
        Port = (ushort)configuration.Port,
      };

      _host.Create(address, _connections.Length, 2, 0, 0, 1024 * 1024);

      var protocolDecoded = RagonVersion.Parse(_protocol);
      _logger.Info($"Listen at 127.0.0.1:{configuration.Port}");
      _logger.Info($"Protocol: {protocolDecoded}");
    }

    public void Update()
    {
      bool polled = false;
      while (!polled)
      {
        if (_host.CheckEvents(out _event) <= 0)
        {
          if (_host.Service(0, out _event) <= 0)
            break;

          polled = true;
        }

        switch (_event.Type)
        {
          case EventType.None:
          {
            _logger.Trace("None event");
            break;
          }
          case EventType.Connect:
          {
            if (!IsValidProtocol(_event.Data))
            {
              _logger.Warn($"Mismatched protocol Server: {RagonVersion.Parse(_protocol)} Client: {RagonVersion.Parse(_event.Data)}, close connection");
              _event.Peer.DisconnectNow(0);
              break;
            }

            var connection = new ENetConnection(_event.Peer);

            _connections[_event.Peer.ID] = connection;
            _listener.OnConnected(connection);
            break;
          }
          case EventType.Disconnect:
          {
            var connection = _connections[_event.Peer.ID];
            _listener.OnDisconnected(connection);
            break;
          }
          case EventType.Timeout:
          {
            var connection = _connections[_event.Peer.ID];
            _listener.OnTimeout(connection);
            break;
          }
          case EventType.Receive:
          {
            var peerId = (ushort)_event.Peer.ID;
            var connection = _connections[peerId];
            var dataRaw = new byte[_event.Packet.Length];

            _event.Packet.CopyTo(dataRaw);
            _event.Packet.Dispose();

            _listener.OnData(connection, (NetworkChannel)_event.ChannelID, dataRaw);
            break;
          }
        }
      }
    }

    public void Broadcast(byte[] data, NetworkChannel channel)
    {
      var packet = new Packet();
      var flag = channel == NetworkChannel.RELIABLE? PacketFlags.Reliable: PacketFlags.None;
      
      packet.Create(data, flag);

      _host.Broadcast((byte)channel, ref packet);
    }
    
    public void Stop()
    {
      _host?.Dispose();

      Library.Deinitialize();
    }

    private bool IsValidProtocol(uint protocol)
    {
      return protocol == _protocol;
    }
  }
}