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

namespace HeuristicLab.Encodings.PermutationEncoding {
  /// <summary>
  /// Manipulates a permutation array by moving randomly one element to another position in the array.
  /// </summary> 
  /// <remarks>
  /// It is implemented as described in Fogel, D.B. (1988). An Evolutionary Approach to the Traveling Salesman Problem, Biological Cybernetics, 60, pp. 139-144.
  /// </remarks>
  [Item("InsertionManipulator", "An operator which moves randomly one element to another position in the permutation. It is implemented as described in Fogel, D.B. (1988). An Evolutionary Approach to the Traveling Salesman Problem, Biological Cybernetics, 60, pp. 139-144.")]
  [StorableClass]
  public class InsertionManipulator : PermutationManipulator {
    /// <summary>
    /// Moves an randomly chosen element in the specified <paramref name="permutation"/> array 
    /// to another randomly generated position.
    /// </summary>
    /// <param name="random">The random number generator.</param>
    /// <param name="permutation">The permutation to manipulate.</param>
    public static void Apply(IRandom random, Permutation permutation) {
      Permutation original = (Permutation)permutation.Clone();
      int cutIndex, insertIndex, number;

      cutIndex = random.Next(original.Length);
      insertIndex = random.Next(original.Length);
      number = original[cutIndex];

      int i = 0;  // index in new permutation
      int j = 0;  // index in old permutation
      while (i < original.Length) {
        if (j == cutIndex) {
          j++;
        }
        if (i == insertIndex) {
          permutation[i] = number;
          i++;
        }
        if ((i < original.Length) && (j < original.Length)) {
          permutation[i] = original[j];
          i++;
          j++;
        }
      }
    }

    /// <summary>
    /// Moves an randomly chosen element in the specified <paramref name="permutation"/> array 
    /// to another randomly generated position.
    /// </summary>
    /// <remarks>Calls <see cref="Apply"/>.</remarks>
    /// <param name="random">A random number generator.</param>
    /// <param name="permutation">The permutation to manipulate.</param>
    protected override void Manipulate(IRandom random, Permutation permutation) {
      Apply(random, permutation);
    }
  }
}