#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2010 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 HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.DebugEngine {

  [StorableClass]
  [Item("Debug Engine", "Engine for debugging algorithms.")]
  public class DebugEngine : Engine {
    private IOperator currentOperator;

    [StorableConstructor]
    protected DebugEngine(bool deserializing) : base(deserializing) { }
    protected DebugEngine(DebugEngine original, Cloner cloner) : base(original, cloner) { }
    public DebugEngine()
      : base() {
    }

    public new Stack<IOperation> ExecutionStack {
      get { return base.ExecutionStack; }
    }

    public IAtomicOperation CurrentOperation { get; private set; }

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

    /// <summary>
    /// Deals with the next operation, if it is an <see cref="AtomicOperation"/> it is executed,
    /// if it is a <see cref="CompositeOperation"/> its single operations are pushed on the execution stack.
    /// </summary>
    /// <remarks>If an error occurs during the execution the operation is aborted and the operation
    /// is pushed on the stack again.<br/>
    /// If the execution was successful <see cref="EngineBase.OnOperationExecuted"/> is called.</remarks>
    protected override void ProcessNextOperation() {
      currentOperator = null;
      IOperation next = ExecutionStack.Pop();
      OperationCollection coll = next as OperationCollection;
      while (coll != null) {
        Log.LogMessage("Expanding OperationCollection");
        for (int i = coll.Count - 1; i >= 0; i--) {
          ExecutionStack.Push(coll[i]);
        }
        next = ExecutionStack.Count > 0 ? ExecutionStack.Pop() : null;
        coll = next as OperationCollection;
      }
      IAtomicOperation operation = next as IAtomicOperation;
      if (operation != null) {
        Log.LogMessage("Preparing IAtomicOperation");
        try {
          currentOperator = operation.Operator;
          CurrentOperation = operation;
          if (operation.Operator.Breakpoint) {
            Log.LogMessage(string.Format("Breakpoint: Before {0}", operation.Operator.Name != string.Empty ? operation.Operator.Name : operation.Operator.ItemName));
            Pause();
          }
          Log.LogMessage("Executing IAtomicOperation");
          ExecutionStack.Push(operation.Operator.Execute((IExecutionContext)operation));
        } catch (Exception ex) {
          OnExceptionOccurred(new OperatorExecutionException(operation.Operator, ex));
          Pause();
        }
      } else {
        Log.LogMessage("Nothing to do");
        CurrentOperation = null;
      }
    }

    public override void Pause() {
      base.Pause();
      if (currentOperator != null) currentOperator.Abort();
    }
    public override void Stop() {
      base.Stop();
      if (currentOperator != null) currentOperator.Abort();
    }

    public virtual void Step() {
      OnStarted();
      var lastUpdateTime = DateTime.Now;
      if (ExecutionStack.Count > 0) {
        while (ExecutionStack.Count > 0 && ExecutionStack.Peek() == null)
          ExecutionStack.Pop();
        if (ExecutionStack.Count > 0)
          ProcessNextOperation();
      }
      ExecutionTime += DateTime.Now - lastUpdateTime;
      OnPaused();
    }
  }
}