#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2019 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 HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HEAL.Attic;

namespace HeuristicLab.Encodings.PermutationEncoding {
  [Item("StochasticSwap2SingleMoveGenerator", "Randomly samples a single from all possible swap-2 moves from a given permutation.")]
  [StorableType("A3F2B5E5-CB79-46FA-8336-69C54F354C1B")]
  public class StochasticSwap2SingleMoveGenerator : Swap2MoveGenerator, IStochasticOperator, ISingleMoveGenerator {
    public ILookupParameter<IRandom> RandomParameter {
      get { return (ILookupParameter<IRandom>)Parameters["Random"]; }
    }

    [StorableConstructor]
    protected StochasticSwap2SingleMoveGenerator(StorableConstructorFlag _) : base(_) { }
    protected StochasticSwap2SingleMoveGenerator(StochasticSwap2SingleMoveGenerator original, Cloner cloner) : base(original, cloner) { }
    public StochasticSwap2SingleMoveGenerator()
      : base() {
      Parameters.Add(new LookupParameter<IRandom>("Random", "The random number generator."));
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new StochasticSwap2SingleMoveGenerator(this, cloner);
    }

    public static Swap2Move Apply(Permutation permutation, IRandom random) {
      int length = permutation.Length;
      if (length < 2) throw new ArgumentException("StochasticSwap2SingleMoveGenerator: There cannot be a swap-2 move given a permutation of length less than 2.", "permutation");
      int index1 = random.Next(length), index2 = 0;
      do {
        index2 = random.Next(length);
      } while (index1 == index2);
      return new Swap2Move(index1, index2);
    }

    protected override Swap2Move[] GenerateMoves(Permutation permutation) {
      IRandom random = RandomParameter.ActualValue;
      return new Swap2Move[] { Apply(permutation, random) };
    }
  }
}