using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Net;
using DistributedGA.Core.Domain;
using DistributedGA.Core.Interface;

namespace DistributedGA.Core.Implementation {
  public class PeerNetworkMessageHandler : IMessageHandler {
    //own peer-instance Information
    private PeerInfo ownInstance = null;

    //uses peer-list from IPeerListManager to decide which peers to contact
    private IPeerListManager peerListManager;

    //uses IMessageSender to send populations to peers
    private IMessageSender sender = null;

    //provides current population for the higher layer IMigrationOperator
    //to queues are used to gather and and provide population more efficiently
    private object activeQueueLocker = new object();
    private ConcurrentQueue<SolutionInfo> writeQueue;
    private ConcurrentQueue<SolutionInfo> readQueue;

    //uses IMessageService for recieving population from one peer at once
    private IMessageService host = null;



    public void Init() {
      try {
        ownInstance = new PeerInfo() {
          IpAddress = GetExternalIpAddress(),
          Port = 0,
          ProblemInstance = "TestProblem"
        }; // TODO: get own peerinfo

        writeQueue = new ConcurrentQueue<SolutionInfo>();
        readQueue = new ConcurrentQueue<SolutionInfo>();

        host = new WcfMessageService();
        ownInstance.Port = host.Init(ownInstance.IpAddress); //getting port, on which service is hostet
        host.OnDataRecieved += new EventHandler<MessageRecieveEventArgs>(OnPopulationRecieved);

        peerListManager = new WcfPeerListManager();
        peerListManager.Init(ownInstance);

        sender = new WcfMessageSender();
        sender.Init(ownInstance);

      } catch (Exception ex) {
        AddError("PeerNetworkMessageHandler.Init", ex);
      }
    }

    public void Dispose() {
      try {
        host.Dispose();
      } catch (Exception ex) {
        AddError("PeerNetworkMessageHandler.Dispose", ex);
      }
    }

    public void PublishDataToNetwork(SolutionInfo[] data) {
      try {
        foreach (PeerInfo peer in peerListManager.GetPeerList()) {
          //HACK: manipulate for monitoring in test
          foreach (SolutionInfo si in data) {
            si.IterationNumber = ownInstance.Port;
          }
          //maybe something will go wrong during network communication...
          try {
            sender.SendData(peer, data);
          } catch (Exception ex) {
            AddError("PeerNetworkMessageHandler.PublishMigrationInfo(during sending to one peer!)", ex);
          }
        }
      } catch (Exception ex) {
        AddError("PeerNetworkMessageHandler.PublishMigrationInfo", ex);
      }
    }

    public SolutionInfo[] GetDataFromNetwork() {
      try {
        List<SolutionInfo> res = new List<SolutionInfo>();
        SolutionInfo item = null;
        lock (activeQueueLocker) {
          var tmp = readQueue;
          readQueue = writeQueue;
          writeQueue = tmp;
        }

        //creating resultset
        while (!readQueue.IsEmpty) {
          if (readQueue.TryDequeue(out item)) {
            res.Add(item);
          }
        }
        return res.ToArray();
      } catch (Exception ex) {
        AddError("PeerNetworkMessageHandler.GetMigrationInfo", ex);
        return null;
      }
    }

    public PeerInfo GetPeerInfo() {
      return ownInstance;
    }

    public List<PeerInfo> GetCurrentNetwork() {
      return peerListManager.GetPeerList();
    }

    private string GetExternalIpAddress() {
      try {
        var strHostName = Dns.GetHostName();
        // Then using host name, get the IP address list..
        IPHostEntry ipEntry = Dns.GetHostEntry(strHostName);
        IPAddress[] addr = ipEntry.AddressList;

        return addr
          .Select(ip => ip.ToString())
          .First(str => str.StartsWith(ConfigurationManager.AppSettings["LanIpPrefix"]));
      } catch { return null; }
    }

    private void OnPopulationRecieved(object sender, MessageRecieveEventArgs e) {
      if (e != null) {
        lock (activeQueueLocker) {
          foreach (SolutionInfo si in e.data) {
            writeQueue.Enqueue(si);
          }
        }
      }
    }

    private void AddError(string source, Exception ex) {
      if (peerListManager != null) {
        try {
          peerListManager.SendLogToServer(string.Concat("Source: ", source, ", Exception: ", ex.Message));
        } catch { }
      }
    }

  }
}