#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2011 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.Text;
using HeuristicLab.Core;
using System.Drawing;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Common;
using HeuristicLab.Collections;
using HeuristicLab.Optimization;
using System.Threading;
using System.Threading.Tasks;

namespace HeuristicLab.SimulationCore {
  [Item("Simulation", "A base class for simulations.")]
  [StorableClass]
  public abstract class Simulation: Algorithm, ISimulation, IStorableContent {
    public string Filename { get; set; }
        
    public override Type ProblemType {
      get { return typeof(IScenario); }
    }

    [Storable]
    private ResultCollection results;
    public override ResultCollection Results {
      get {
        return results;
      }
    }

    #region Variables for communication between threads
    private CancellationTokenSource cancellationTokenSource;
    private bool stopPending;
    private DateTime lastUpdateTime;
    #endregion

    [StorableConstructor]
    protected Simulation(bool deserializing) : base(deserializing) { }
    protected Simulation()
      : base() {
        results = new ResultCollection();
    }
    protected Simulation(Simulation original, Cloner cloner)
      : base(original, cloner) {
        results = cloner.Clone(original.results) as ResultCollection;
    }

    public sealed override void Prepare() {
      base.Prepare();
      results.Clear();
      OnPrepared();
    }
    protected override void OnPrepared() {
      base.OnPrepared();
    }

    private class RunInformation {
      public CancellationTokenSource CancellationToken { get; set; }
      public IExecutionContext ExecutionContext { get; set; }
    }

    public virtual void Start(IExecutionContext executionContext) {
      base.Start();

      RunInformation runInfo = new RunInformation();
      cancellationTokenSource = new CancellationTokenSource();
      runInfo.CancellationToken = cancellationTokenSource;
      runInfo.ExecutionContext = executionContext;
      stopPending = false;
      Task task = Task.Factory.StartNew(Run, runInfo, runInfo.CancellationToken.Token);
      task.ContinueWith(t => {
        try {
          t.Wait();
        }
        catch (AggregateException ex) {
          try {
            ex.Flatten().Handle(x => x is OperationCanceledException);
          }
          catch (AggregateException remaining) {
            if (remaining.InnerExceptions.Count == 1) OnExceptionOccurred(remaining.InnerExceptions[0]);
            else OnExceptionOccurred(remaining);
          }
        }
        cancellationTokenSource.Dispose();
        cancellationTokenSource = null;
        if (stopPending) OnStopped();
        else OnPaused();
      });
    }

    public override void Start() {
      Start(null);      
    }
    protected override void OnStarted() {
      base.OnStarted();
    }

    public override void Pause() {
      base.Pause();
      cancellationTokenSource.Cancel();
    }
    protected override void OnPaused() {
      base.OnPaused();
    }

    public override void Stop() {
      base.Stop();
      if (ExecutionState == ExecutionState.Paused) {
        OnStopped();
      } else {
        stopPending = true;
        cancellationTokenSource.Cancel();
      }
    }
    protected override void OnStopped() {
      base.OnStopped();
    }

    protected override void OnExceptionOccurred(Exception exception) {
      base.OnExceptionOccurred(exception);
    }

    private void Run(object state) {
      RunInformation runInfo = (RunInformation)state;

      OnStarted();
      lastUpdateTime = DateTime.Now;
      System.Timers.Timer timer = new System.Timers.Timer(250);
      timer.AutoReset = true;
      timer.Elapsed += new System.Timers.ElapsedEventHandler(timer_Elapsed);
      timer.Start();
      try {
        foreach (IParameter parameter in Parameters) {
          if(parameter is ILookupParameter)
            (parameter as ILookupParameter).ExecutionContext = runInfo.ExecutionContext;
        }

        Run(runInfo.CancellationToken.Token);
      }
      finally {
        timer.Elapsed -= new System.Timers.ElapsedEventHandler(timer_Elapsed);
        timer.Stop();
        ExecutionTime += DateTime.Now - lastUpdateTime;

        foreach (IParameter parameter in Parameters) {
          if (parameter is ILookupParameter)
            (parameter as ILookupParameter).ExecutionContext = null;
        }
      }
      Stop();

      runInfo.CancellationToken.Token.ThrowIfCancellationRequested();
    }
    protected abstract void Run(CancellationToken cancellationToken);

    private void timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e) {
      System.Timers.Timer timer = (System.Timers.Timer)sender;
      timer.Enabled = false;
      DateTime now = DateTime.Now;
      ExecutionTime += now - lastUpdateTime;
      lastUpdateTime = now;
      timer.Enabled = true;
    }
  }
}