#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.Linq;
using System.Reflection;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Scripting;

namespace HeuristicLab.Problems.Programmable {
  [Item("ProblemDefinitionScript", "Script that defines the parameter vector and evaluates the solution for a programmable problem.")]
  [StorableClass]
  public abstract class ProblemScript : Script {
    protected bool SuppressEvents { get; set; }

    [Storable]
    private VariableStore variableStore;
    public VariableStore VariableStore {
      get { return variableStore; }
    }

    [StorableConstructor]
    protected ProblemScript(bool deserializing) : base(deserializing) { }
    protected ProblemScript(ProblemScript original, Cloner cloner)
      : base(original, cloner) {
      variableStore = cloner.Clone(original.variableStore);
    }
    protected ProblemScript() {
      variableStore = new VariableStore();
    }

    private volatile IProblemDefinition instance;
    private object locker = new object();
    public IProblemDefinition Instance {
      get {
        SuppressEvents = true;
        try {
          var oldInstance = instance;
          var compilationNecessary = false;
          if (instance == null) {
            lock (locker) {
              if (instance == null) {
                compilationNecessary = true;
                Compile();
              }
            }
          }
          if (compilationNecessary && (oldInstance != null || instance != null))
            OnInstanceChanged();
          return instance;
        } finally {
          SuppressEvents = false;
        }
      }
      protected set {
        instance = value;
        if (!SuppressEvents) OnInstanceChanged();
      }
    }

    public override Assembly Compile() {
      var assembly = base.Compile();
      var types = assembly.GetTypes();
      try {
        var inst = (ProblemScriptBase)Activator.CreateInstance(types.First(x => typeof(ProblemScriptBase).IsAssignableFrom(x)));
        inst.vars = new Variables(VariableStore);
        inst.Initialize();
        Instance = inst;
      } catch {
        Instance = null;
      }
      return assembly;
    }

    protected override void OnCodeChanged() {
      base.OnCodeChanged();
      instance = null;
    }

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