#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 HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Encodings.PermutationEncoding;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Problems.TravelingSalesman {
  /// <summary>
  /// A base class for operators which evaluate TSP solutions given in path representation using city coordinates.
  /// </summary>
  [Item("TSPCoordinatesPathEvaluator", "A base class for operators which evaluate TSP solutions given in path representation using city coordinates.")]
  [StorableClass]
  public abstract class TSPCoordinatesPathEvaluator : TSPEvaluator, ITSPCoordinatesPathEvaluator {
    private object locker = new object();

    public ILookupParameter<Permutation> PermutationParameter {
      get { return (ILookupParameter<Permutation>)Parameters["Permutation"]; }
    }
    public ILookupParameter<DoubleMatrix> CoordinatesParameter {
      get { return (ILookupParameter<DoubleMatrix>)Parameters["Coordinates"]; }
    }
    public ILookupParameter<DistanceMatrix> DistanceMatrixParameter {
      get { return (ILookupParameter<DistanceMatrix>)Parameters["DistanceMatrix"]; }
    }
    public ILookupParameter<BoolValue> UseDistanceMatrixParameter {
      get { return (ILookupParameter<BoolValue>)Parameters["UseDistanceMatrix"]; }
    }

    [StorableConstructor]
    protected TSPCoordinatesPathEvaluator(bool deserializing) : base(deserializing) { }
    protected TSPCoordinatesPathEvaluator(TSPCoordinatesPathEvaluator original, Cloner cloner) : base(original, cloner) { }
    protected TSPCoordinatesPathEvaluator()
      : base() {
      Parameters.Add(new LookupParameter<Permutation>("Permutation", "The TSP solution given in path representation which should be evaluated."));
      Parameters.Add(new LookupParameter<DoubleMatrix>("Coordinates", "The x- and y-Coordinates of the cities."));
      Parameters.Add(new LookupParameter<DistanceMatrix>("DistanceMatrix", "The matrix which contains the distances between the cities."));
      Parameters.Add(new LookupParameter<BoolValue>("UseDistanceMatrix", "True if a distance matrix should be calculated and used for evaluation, otherwise false."));
    }

    [StorableHook(HookType.AfterDeserialization)]
    private void AfterDeserialization() {
      // BackwardsCompatibility3.3
      #region Backwards compatible code (remove with 3.4)
      LookupParameter<DoubleMatrix> oldDistanceMatrixParameter = Parameters["DistanceMatrix"] as LookupParameter<DoubleMatrix>;
      if (oldDistanceMatrixParameter != null) {
        Parameters.Remove(oldDistanceMatrixParameter);
        Parameters.Add(new LookupParameter<DistanceMatrix>("DistanceMatrix", "The matrix which contains the distances between the cities."));
        DistanceMatrixParameter.ActualName = oldDistanceMatrixParameter.ActualName;
      }
      #endregion
    }

    public static double Apply(TSPCoordinatesPathEvaluator evaluator, DoubleMatrix coordinates, Permutation tour) {
      DoubleMatrix c = coordinates;
      Permutation p = tour;
      double length = 0;
      for (int i = 0; i < p.Length - 1; i++)
        length += evaluator.CalculateDistance(c[p[i], 0], c[p[i], 1], c[p[i + 1], 0], c[p[i + 1], 1]);
      length += evaluator.CalculateDistance(c[p[p.Length - 1], 0], c[p[p.Length - 1], 1], c[p[0], 0], c[p[0], 1]);
      return length;
    }

    public sealed override IOperation InstrumentedApply() {
      if (UseDistanceMatrixParameter.ActualValue.Value) {
        Permutation p = PermutationParameter.ActualValue;
        DistanceMatrix dm = DistanceMatrixParameter.ActualValue;

        if (dm == null) {  // calculate distance matrix
          lock (locker) {
            dm = DistanceMatrixParameter.ActualValue;
            if (dm == null) {  // check again to avoid race condition
              DoubleMatrix c = CoordinatesParameter.ActualValue;
              if (c == null) throw new InvalidOperationException("Neither a distance matrix nor coordinates were given.");
              dm = new DistanceMatrix(c.Rows, c.Rows);
              for (int i = 0; i < dm.Rows; i++) {
                for (int j = 0; j < dm.Columns; j++)
                  dm[i, j] = CalculateDistance(c[i, 0], c[i, 1], c[j, 0], c[j, 1]);
              }
              DistanceMatrixParameter.ActualValue = (DistanceMatrix)dm.AsReadOnly();
            }
          }
        }

        double length = 0;
        for (int i = 0; i < p.Length - 1; i++)
          length += dm[p[i], p[i + 1]];
        length += dm[p[p.Length - 1], p[0]];
        QualityParameter.ActualValue = new DoubleValue(length);
      } else {
        Permutation p = PermutationParameter.ActualValue;
        DoubleMatrix c = CoordinatesParameter.ActualValue;
        if (c == null) throw new InvalidOperationException("No coordinates were given.");
        double length = 0;
        for (int i = 0; i < p.Length - 1; i++)
          length += CalculateDistance(c[p[i], 0], c[p[i], 1], c[p[i + 1], 0], c[p[i + 1], 1]);
        length += CalculateDistance(c[p[p.Length - 1], 0], c[p[p.Length - 1], 1], c[p[0], 0], c[p[0], 1]);
        QualityParameter.ActualValue = new DoubleValue(length);
      }
      return base.InstrumentedApply();
    }

    /// <summary>
    /// Calculates the distance between two points.
    /// </summary>
    /// <param name="x1">The x-coordinate of point 1.</param>
    /// <param name="y1">The y-coordinate of point 1.</param>
    /// <param name="x2">The x-coordinate of point 2.</param>
    /// <param name="y2">The y-coordinate of point 2.</param>
    /// <returns>The calculated distance.</returns>
    protected abstract double CalculateDistance(double x1, double y1, double x2, double y2);
  }
}