#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.Collections.Generic;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Data;
using HeuristicLab.Parameters;
using HeuristicLab.Problems.VehicleRouting.Encodings.Potvin;
using HeuristicLab.Problems.VehicleRouting.Encodings;
using HeuristicLab.Problems.VehicleRouting;
using System;

namespace HeuristicLab.Analysis.FitnessLandscape.VRP {
  [Item("TwoOptManipulator", "Two opt manipulation")]
  [StorableClass]
  public sealed class TwoOptManipulator : PotvinManipulator {
    [StorableConstructor]
    private TwoOptManipulator(bool deserializing) : base(deserializing) { }
    private TwoOptManipulator(TwoOptManipulator original, Cloner cloner)
      : base(original, cloner) {
    }
    public override IDeepCloneable Clone(Cloner cloner) {
      return new TwoOptManipulator(this, cloner);
    }
    public TwoOptManipulator()
      : base() {
    }

    public static void Apply(IRandom random, PotvinEncoding individual) {
      List<Tour> tours = individual.Tours.FindAll(t => t.Cities.Count >= 4);

      if (tours.Count > 0) {
        int tourIdx = random.Next(tours.Count);
        Tour tour = tours[tourIdx];

        int a;
        if (tour.Cities.Count == 4) {
            a = 0;
        } else if (tour.Cities.Count == 5) {
          int idx = random.Next(4);
          if (idx >= 2)
            idx++;
          a = idx;
        } else {
          a = random.Next(tour.Cities.Count);
        }

        int b;
        List<int> indices = new List<int>();
        for (int i = 0; i < tour.Cities.Count; i++) {
          if (Math.Abs(i - a) > 2) {
            indices.Add(i);
          }
        }
        b = indices[random.Next(indices.Count)];

        if (b < a) {
          int tmp = a;
          a = b;
          b = tmp;
        }

        int index = a + 1;
        int count = b - a - 1;
        List<int> segment = tour.Cities.GetRange(index, count);
        tour.Cities.RemoveRange(index, count);
        segment.Reverse();
        tour.Cities.InsertRange(index, segment);
      }
    }

    protected override void Manipulate(IRandom random, PotvinEncoding individual) {
      Apply(random, individual);
    }
  }
}