#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2014 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using HeuristicLab.Common;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace HeuristicLab.Core.Networks {
  [Item("MessagePort", "A port of a network node for sending and receiving messages.")]
  [StorableClass]
  public class MessagePort : ParameterizedPort, IMessagePort {
    public override Image ItemImage {
      get {
        if (PortConnectionValid) return base.ItemImage;
        else return HeuristicLab.Common.Resources.VSImageLibrary.Error;
      }
    }

    new public PortParameterCollection Parameters {
      get { return base.Parameters; }
    }

    [Storable]
    protected IMessagePort connectedPort;
    public IMessagePort ConnectedPort {
      get { return connectedPort; }
      set {
        if (connectedPort != value) {
          DeregisterConnectedPortEvents();
          connectedPort = value;
          RegisterConnectedPortEvents();
          OnConnectedPortChanged();
          CheckPortConnection();
        }
      }
    }
    IPort IConnectablePort.ConnectedPort {
      get { return ConnectedPort; }
      set {
        if (!(value is IMessagePort))
          throw new InvalidOperationException("Type mismatch. ConnectedPort is not an IMessagePort.");
        ConnectedPort = (IMessagePort)value;
      }
    }
    [Storable]
    protected bool portConnectionValid;
    public bool PortConnectionValid {
      get { return portConnectionValid; }
      protected set {
        if (value != portConnectionValid) {
          portConnectionValid = value;
          OnPortConnectionValidChanged();
          OnItemImageChanged();
        }
      }
    }
    [Storable]
    protected IMessage lastMessage;
    public IMessage LastMessage {
      get { return lastMessage; }
      protected set {
        if (value != lastMessage) {
          lastMessage = value;
          OnLastMessageChanged();
        }
      }
    }

    [StorableConstructor]
    protected MessagePort(bool deserializing) : base(deserializing) { }
    protected MessagePort(MessagePort original, Cloner cloner)
      : base(original, cloner) {
      connectedPort = cloner.Clone(original.connectedPort);
      portConnectionValid = original.portConnectionValid;
      lastMessage = null;
      RegisterConnectedPortEvents();
    }
    public MessagePort()
      : base("MessagePort") {
      portConnectionValid = true;
      lastMessage = null;
    }
    public MessagePort(string name)
      : base(name) {
      portConnectionValid = true;
      lastMessage = null;
    }
    public MessagePort(string name, string description)
      : base(name, description) {
      portConnectionValid = true;
      lastMessage = null;
    }

    [StorableHook(HookType.AfterDeserialization)]
    private void AfterDeserialization() {
      RegisterConnectedPortEvents();
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new MessagePort(this, cloner);
    }

    public bool CanConnectToPort(IPort port) {
      return (port == null) || (port is IMessagePort);
    }

    public IMessage PrepareMessage() {
      if (!PortConnectionValid) throw new InvalidOperationException("Port connection is not valid");
      var message = new Message();

      // collect output parameters from local port
      message.Values.AddRange(
        Parameters
          .Where(p => p.Type.HasFlag(PortParameterType.Output))
          .Select(p => p.CreateMessageValue())
      );

      // collect remaining parameters from connected port
      if (ConnectedPort != null) {
        message.Values.AddRange(
          ConnectedPort.Parameters
            .Where(p => !message.Values.ContainsKey(p.Name))
            .Select(p => p.CreateMessageValue())
        );
      }

      // collect remaining input parameters from local port
      message.Values.AddRange(
        Parameters
          .Where(p => p.Type.HasFlag(PortParameterType.Input) && !message.Values.ContainsKey(p.Name))
          .Select(p => p.CreateMessageValue())
      );

      return message;
    }
    public void SendMessage(IMessage message) {
      SendMessage(message, CancellationToken.None);
    }
    public void SendMessage(IMessage message, CancellationToken token) {
      if (!PortConnectionValid) throw new InvalidOperationException("Port connection is not valid");
      if (ConnectedPort != null) ConnectedPort.ReceiveMessage(message, token);
      LastMessage = message;
      OnMessageSent(message, token);
    }
    public async Task SendMessageAsync(IMessage message) {
      await SendMessageAsync(message, CancellationToken.None);
    }
    public async Task SendMessageAsync(IMessage message, CancellationToken token) {
      await Task.Run(() => { SendMessage(message, token); }, token);
    }
    public event EventHandler<EventArgs<IMessage, CancellationToken>> MessageSent;
    protected virtual void OnMessageSent(IMessage message, CancellationToken token) {
      var handler = MessageSent;
      if (handler != null) handler(this, new EventArgs<IMessage, CancellationToken>(message, token));
    }

    public void ReceiveMessage(IMessage message, CancellationToken token) {
      if (!PortConnectionValid) throw new InvalidOperationException("Port connection is not valid");
      LastMessage = message;
      OnMessageReceived(message, token);
      token.ThrowIfCancellationRequested();
    }
    public event EventHandler<EventArgs<IMessage, CancellationToken>> MessageReceived;
    protected virtual void OnMessageReceived(IMessage message, CancellationToken token) {
      var handler = MessageReceived;
      if (handler != null) handler(this, new EventArgs<IMessage, CancellationToken>(message, token));
    }

    public event EventHandler ConnectedPortChanged;
    protected virtual void OnConnectedPortChanged() {
      var handler = ConnectedPortChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler PortConnectionValidChanged;
    protected virtual void OnPortConnectionValidChanged() {
      var handler = PortConnectionValidChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler LastMessageChanged;
    protected virtual void OnLastMessageChanged() {
      var handler = LastMessageChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }

    protected override void OnInterfaceChanged() {
      CheckPortConnection();
      base.OnInterfaceChanged();
    }

    #region ConnectedPort Events
    protected virtual void RegisterConnectedPortEvents() {
      if (connectedPort != null) {
        connectedPort.InterfaceChanged += ConnectedPort_InterfaceChanged;
        connectedPort.MessageSent += ConnectedPort_MessageSent;
      }
    }
    protected virtual void DeregisterConnectedPortEvents() {
      if (connectedPort != null) {
        connectedPort.InterfaceChanged -= ConnectedPort_InterfaceChanged;
        connectedPort.MessageSent -= ConnectedPort_MessageSent;
      }
    }
    protected virtual void ConnectedPort_InterfaceChanged(object sender, EventArgs e) {
      CheckPortConnection();
    }
    protected virtual void ConnectedPort_MessageSent(object sender, EventArgs<IMessage, CancellationToken> e) {
      ReceiveMessage(e.Value, e.Value2);
    }
    #endregion

    #region Helpers
    protected virtual void CheckPortConnection() {
      PortConnectionValid = (ConnectedPort == null) ||
                            (ParametersCompatibleToTarget(Parameters, ConnectedPort.Parameters) &&
                             ParametersCompatibleToTarget(ConnectedPort.Parameters, Parameters));
    }
    protected virtual bool ParametersCompatibleToTarget(IEnumerable<IPortParameter> source, IEnumerable<IPortParameter> target) {
      // checks if the source parameters are compatible to the input parameters of the target
      foreach (var input in target.Where(p => p.Type.HasFlag(PortParameterType.Input))) {
        var param = source.Where(p => input.Name == p.Name).FirstOrDefault();
        if (param == null) {
          if (input.DefaultValue == null) return false;
        } else {
          if (!param.Type.HasFlag(PortParameterType.Output)) return false;
          if (!input.DataType.IsAssignableFrom(param.DataType)) return false;
        }
      }
      return true;
    }
    #endregion
  }
}