#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2018 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 System.Linq;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Optimization;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Encodings.PermutationEncoding {
  [Item("ExhaustiveInsertionMoveGenerator", "Generates all possible insertion moves (3-opt) from a given permutation.")]
  [StorableClass]
  public class ExhaustiveInsertionMoveGenerator : TranslocationMoveGenerator, IExhaustiveMoveGenerator {
    [StorableConstructor]
    protected ExhaustiveInsertionMoveGenerator(bool deserializing) : base(deserializing) { }
    protected ExhaustiveInsertionMoveGenerator(ExhaustiveInsertionMoveGenerator original, Cloner cloner) : base(original, cloner) { }
    public ExhaustiveInsertionMoveGenerator() : base() { }

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

    public static IEnumerable<TranslocationMove> Generate(Permutation permutation) {
      int length = permutation.Length;
      if (length == 1) throw new ArgumentException("ExhaustiveInsertionMoveGenerator: There cannot be an insertion move given a permutation of length 1.", "permutation");

      if (permutation.PermutationType == PermutationTypes.Absolute) {
        for (int i = 0; i < length; i++) {
          for (int j = 1; j <= length - 1; j++) {
            yield return new TranslocationMove(i, i, (i + j) % length);
          }
        }
      } else {
        if (length > 2) {
          for (int i = 0; i < length; i++) {
            for (int j = 1; j <= length - 1; j++) {
              if (i == 0 && j == length - 1
                || i == length - 1 && j == 1) continue;
              yield return new TranslocationMove(i, i, (i + j) % length);
            }
          }
        } else { // doesn't make sense, but just create a dummy move to not crash the algorithms
          yield return new TranslocationMove(0, 0, 1);
        }
      }
    }

    public static TranslocationMove[] Apply(Permutation permutation) {
      return Generate(permutation).ToArray();
    }

    protected override TranslocationMove[] GenerateMoves(Permutation permutation) {
      return Apply(permutation);
    }
  }
}