#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 System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Core.Networks;
using HeuristicLab.Operators;
using HeuristicLab.Optimization;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Networks {
  [Item("AlgorithmNode", "A node of a network which contains a HeuristicLab algorithm.")]
  [StorableClass]
  public class AlgorithmNode : Node, IAlgorithmNode {
    protected object locker = new object();

    new public PortCollection Ports {
      get { return base.Ports; }
    }

    [Storable]
    private IAlgorithm algorithm;
    public IAlgorithm Algorithm {
      get { return algorithm; }
      set {
        if (value != algorithm) {
          algorithm = value;
          OnAlgorithmChanged();
        }
      }
    }

    [Storable]
    private RunCollection runs;
    public RunCollection Runs {
      get { return runs; }
    }

    [Storable]
    private IItemCollection<IAlgorithm> startedAlgorithms;
    public IItemCollection<IAlgorithm> StartedAlgorithms {
      get { return startedAlgorithms; }
    }

    [StorableConstructor]
    protected AlgorithmNode(bool deserializing) : base(deserializing) { }
    protected AlgorithmNode(AlgorithmNode original, Cloner cloner)
      : base(original, cloner) {
      algorithm = cloner.Clone(original.algorithm);
      runs = cloner.Clone(original.runs);
      startedAlgorithms = cloner.Clone(original.startedAlgorithms);
      RegisterStartedAlgorithmsEvents();
    }
    public AlgorithmNode()
      : base("AlgorithmNode") {
      runs = new RunCollection();
      startedAlgorithms = new ItemCollection<IAlgorithm>();
      RegisterStartedAlgorithmsEvents();
    }

    public AlgorithmNode(string name)
      : base(name) {
      runs = new RunCollection();
      startedAlgorithms = new ItemCollection<IAlgorithm>();
      RegisterStartedAlgorithmsEvents();
    }
    public AlgorithmNode(string name, string description)
      : base(name, description) {
      runs = new RunCollection();
      startedAlgorithms = new ItemCollection<IAlgorithm>();
      RegisterStartedAlgorithmsEvents();
    }

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

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

    protected virtual void RegisterStartedAlgorithmsEvents() {
      startedAlgorithms.ItemsAdded += StartedAlgorithms_ItemsChanged;
      startedAlgorithms.ItemsRemoved += StartedAlgorithms_ItemsChanged;
    }

    private void StartedAlgorithms_ItemsChanged(object sender, Collections.CollectionItemsChangedEventArgs<IAlgorithm> e) {
      OnStartedAlgorithmsChanged();
    }

    protected virtual void Configure(IConfigurationPort port, IMessage message, CancellationToken token) {
      // set algorithm and problem parameters
      lock (locker) {
        if (algorithm != null) {
          foreach (var v in message.Values) {
            IParameter param = null;
            if (Algorithm.Parameters.TryGetValue(v.Name, out param)) {
              var vp = param as IValueParameter;
              if (vp != null) vp.Value = v.Value;
            }
            if (Algorithm.Problem.Parameters.TryGetValue(v.Name, out param)) {
              var vp = param as IValueParameter;
              if (vp != null) vp.Value = v.Value;
            }
          }
        }
      }
    }

    protected virtual void Execute(IExecutionPort port, IMessage message, CancellationToken token) {
      if (Algorithm == null) throw new InvalidOperationException("Algorithm is null");

      IAlgorithm algorithm;
      lock (locker) {
        // prevent cloning of ports in hook operators
        var cloner = new Cloner();
        foreach (var hook in Algorithm.GetObjectGraphObjects(new HashSet<object>() { Algorithm.Results, Algorithm.Runs }).OfType<IHookOperator>()) {
          cloner.RegisterClonedObject(hook.Port, hook.Port);
        }
        algorithm = (IAlgorithm)Algorithm.Clone(cloner);
      }

      // set parameters
      foreach (var v in message.Values) {
        IParameter param = null;
        if (algorithm.Parameters.TryGetValue(v.Name, out param)) {
          var vp = param as IValueParameter;
          if (vp != null) vp.Value = v.Value;
        }
        if (algorithm.Problem.Parameters.TryGetValue(v.Name, out param)) {
          var vp = param as IValueParameter;
          if (vp != null) vp.Value = v.Value;
        }
      }

      token.ThrowIfCancellationRequested();

      Exception exception = null;
      using (var started = new AutoResetEvent(false))
      using (var stopped = new AutoResetEvent(false))
      using (var ctr = token.Register(() => {
        started.WaitOne();
        try { algorithm.Stop(); }
        catch (InvalidOperationException) {
          // NOTE:
          // After the algorithm's engine is stopped, all stateful items in the algorithm are cleared before the execution state of the algorithm is set to stopped.
          // When algorithm.Stop() is called during that operation, an InvalidOperationException is thrown because Stop is called on the engine but the engine is already stopped.
          // This exception can be ignored, as the algorithm will stop immediately after the clearing of its stateful items is finished.
        }
      })) {
        algorithm.StoreAlgorithmInEachRun = false;
        algorithm.Prepare(true);
        algorithm.ExceptionOccurred += (sender, args) => { exception = args.Value; };
        algorithm.Started += (sender, args) => { started.Set(); startedAlgorithms.Add((IAlgorithm)sender); };
        algorithm.Stopped += (sender, args) => { stopped.Set(); startedAlgorithms.Remove((IAlgorithm)sender); };
        algorithm.Start();
        stopped.WaitOne();
      }

      if (exception != null) throw exception;
      token.ThrowIfCancellationRequested();

      // retrieve results
      var run = algorithm.Runs.First();
      foreach (var v in message.Values) {
        IItem result = null;
        if (run.Results.TryGetValue(v.Name, out result)) {
          v.Value = result;
        }
      }

      lock (locker) {
        Runs.Add(run);
      }
    }

    public event EventHandler AlgorithmChanged;
    protected virtual void OnAlgorithmChanged() {
      var handler = AlgorithmChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }

    public event EventHandler StartedAlgorithmsChanged;
    protected virtual void OnStartedAlgorithmsChanged() {
      var handler = StartedAlgorithmsChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }

    #region Ports Events
    protected override void RegisterPortsEvents() {
      base.RegisterPortsEvents();
      foreach (var p in Ports)
        RegisterPortEvents(p);
    }
    protected override void Ports_ItemsAdded(object sender, Collections.CollectionItemsChangedEventArgs<IPort> e) {
      base.Ports_ItemsAdded(sender, e);
      foreach (var p in e.Items)
        RegisterPortEvents(p);
    }
    protected override void Ports_ItemsRemoved(object sender, Collections.CollectionItemsChangedEventArgs<IPort> e) {
      base.Ports_ItemsRemoved(sender, e);
      foreach (var p in e.Items)
        DeregisterPortEvents(p);
    }
    protected override void Ports_ItemsReplaced(object sender, Collections.CollectionItemsChangedEventArgs<IPort> e) {
      base.Ports_ItemsReplaced(sender, e);
      foreach (var p in e.OldItems)
        DeregisterPortEvents(p);
      foreach (var p in e.Items)
        RegisterPortEvents(p);
    }
    protected override void Ports_CollectionReset(object sender, Collections.CollectionItemsChangedEventArgs<IPort> e) {
      base.Ports_CollectionReset(sender, e);
      foreach (var p in e.OldItems)
        DeregisterPortEvents(p);
      foreach (var p in e.Items)
        RegisterPortEvents(p);
    }
    #endregion

    #region Port Events
    private void RegisterPortEvents(IPort port) {
      IConfigurationPort c = port as IConfigurationPort;
      if (c != null) {
        c.MessageReceived += ConfigurationPort_MessageReceived;
      }
      IExecutionPort e = port as IExecutionPort;
      if (e != null) {
        e.MessageReceived += ExecutionPort_MessageReceived;
      }
    }
    private void DeregisterPortEvents(IPort port) {
      IConfigurationPort c = port as IConfigurationPort;
      if (c != null) {
        c.MessageReceived -= ConfigurationPort_MessageReceived;
      }
      IExecutionPort e = port as IExecutionPort;
      if (e != null) {
        e.MessageReceived -= ExecutionPort_MessageReceived;
      }
    }
    protected virtual void ConfigurationPort_MessageReceived(object sender, EventArgs<IMessage, CancellationToken> e) {
      Configure((IConfigurationPort)sender, e.Value, e.Value2);
    }
    protected virtual void ExecutionPort_MessageReceived(object sender, EventArgs<IMessage, CancellationToken> e) {
      Execute((IExecutionPort)sender, e.Value, e.Value2);
    }
    #endregion
  }
}