#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.Drawing;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Operators {
  /// <summary>
  /// The base class for all operators.
  /// </summary>
  [Item("Operator", "Base class for operators.")]
  [StorableClass]
  public abstract class Operator : ParameterizedNamedItem, IOperator {
    public override Image ItemImage {
      get {
        if (Breakpoint) return HeuristicLab.Common.Resources.VS2008ImageLibrary.BreakpointActive;
        else return HeuristicLab.Common.Resources.VS2008ImageLibrary.Method;
      }
    }
    public override bool CanChangeDescription {
      get { return false; }
    }

    [Storable]
    private IExecutionContext executionContext;
    protected IExecutionContext ExecutionContext {
      get { return executionContext; }
      private set {
        if (value != executionContext) {
          executionContext = value;
          OnExecutionContextChanged();
        }
      }
    }

    /// <summary>
    /// Flag whether the current instance has been canceled.
    /// </summary>
    private bool canceled;
    /// <inheritdoc/>
    protected bool Canceled {
      get { return canceled; }
      private set {
        if (value != canceled) {
          canceled = value;
          OnCanceledChanged();
        }
      }
    }

    [Storable]
    private bool breakpoint;
    /// <inheritdoc/>
    /// <remarks>Calls <see cref="OnBreakpointChanged"/> in the setter.</remarks>
    public bool Breakpoint {
      get { return breakpoint; }
      set {
        if (value != breakpoint) {
          breakpoint = value;
          OnBreakpointChanged();
          OnItemImageChanged();
        }
      }
    }

    [StorableConstructor]
    protected Operator(bool deserializing) : base(deserializing) { }
    protected Operator(Operator original, Cloner cloner)
      : base(original, cloner) {
      this.canceled = original.canceled;
      this.breakpoint = original.breakpoint;
      this.executionContext = cloner.Clone<IExecutionContext>(original.executionContext);
    }
    /// <summary>
    /// Initializes a new instance of <see cref="OperatorBase"/> setting the breakpoint flag and 
    /// the canceled flag to <c>false</c> and the name of the operator to the type name. 
    /// </summary>
    protected Operator()
      : base() {
      canceled = false;
      breakpoint = false;
    }
    protected Operator(string name)
      : base(name) {
      canceled = false;
      breakpoint = false;
    }
    protected Operator(string name, ParameterCollection parameters)
      : base(name, parameters) {
      canceled = false;
      breakpoint = false;
    }
    protected Operator(string name, string description)
      : base(name, description) {
      canceled = false;
      breakpoint = false;
    }
    protected Operator(string name, string description, ParameterCollection parameters)
      : base(name, description, parameters) {
      canceled = false;
      breakpoint = false;
    }

    /// <inheritdoc/>
    public virtual IOperation Execute(IExecutionContext context) {
      try {
        Canceled = false;
        ExecutionContext = context;
        foreach (IParameter param in Parameters)
          param.ExecutionContext = context;
        IOperation next = Apply();
        OnExecuted();
        return next;
      }
      finally {
        foreach (IParameter param in Parameters)
          param.ExecutionContext = null;
        ExecutionContext = null;
      }
    }
    /// <inheritdoc/>
    /// <remarks>Sets property <see cref="Canceled"/> to <c>true</c>.</remarks>
    public void Abort() {
      Canceled = true;
    }
    /// <summary>
    /// Performs the current operator on the specified <paramref name="scope"/>.
    /// </summary>
    /// <param name="scope">The scope where to execute the operator</param>
    /// <returns><c>null</c>.</returns>
    public abstract IOperation Apply();

    protected virtual void OnExecutionContextChanged() { }
    protected virtual void OnCanceledChanged() { }
    /// <inheritdoc/>
    public event EventHandler BreakpointChanged;
    /// <summary>
    /// Fires a new <c>BreakpointChanged</c> event.
    /// </summary>
    protected virtual void OnBreakpointChanged() {
      if (BreakpointChanged != null) {
        BreakpointChanged(this, EventArgs.Empty);
      }
    }
    /// <inheritdoc/>
    public event EventHandler Executed;
    /// <summary>
    /// Fires a new <c>Executed</c> event.
    /// </summary>
    protected virtual void OnExecuted() {
      if (Executed != null) {
        Executed(this, EventArgs.Empty);
      }
    }
  }
}