#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2016 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 * Implementation is based on jMetal framework https://github.com/jMetal/jMetal
 *
 * 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.Analysis;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Encodings.RealVectorEncoding;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Problems.TestFunctions;
using HeuristicLab.Random;
using System;
using System.Collections.Generic;
using System.Threading;

namespace HeuristicLab.Algorithms.DifferentialEvolution {

  [Item("Differential Evolution (DE)", "A differential evolution algorithm.")]
  [StorableClass]
  [Creatable(CreatableAttribute.Categories.PopulationBasedAlgorithms, Priority = 400)]
  public class DifferentialEvolution : BasicAlgorithm {
    public Func<IEnumerable<double>, double> Evaluation;

    public override Type ProblemType {
      get { return typeof(SingleObjectiveTestFunctionProblem); }
    }
    public new SingleObjectiveTestFunctionProblem Problem {
      get { return (SingleObjectiveTestFunctionProblem)base.Problem; }
      set { base.Problem = value; }
    }

    private readonly IRandom _random = new MersenneTwister();
    private int evals;

    #region ParameterNames
    private const string MaximumEvaluationsParameterName = "Maximum Evaluations";
    private const string SeedParameterName = "Seed";
    private const string SetSeedRandomlyParameterName = "SetSeedRandomly";
    private const string CrossoverProbabilityParameterName = "CrossoverProbability";
    private const string PopulationSizeParameterName = "PopulationSize";
    private const string ScalingFactorParameterName = "ScalingFactor";
    private const string ValueToReachParameterName = "ValueToReach";
    #endregion

    #region ParameterProperties
    public IFixedValueParameter<IntValue> MaximumEvaluationsParameter {
      get { return (IFixedValueParameter<IntValue>)Parameters[MaximumEvaluationsParameterName]; }
    }
    public IFixedValueParameter<IntValue> SeedParameter {
      get { return (IFixedValueParameter<IntValue>)Parameters[SeedParameterName]; }
    }
    public FixedValueParameter<BoolValue> SetSeedRandomlyParameter {
      get { return (FixedValueParameter<BoolValue>)Parameters[SetSeedRandomlyParameterName]; }
    }
    private ValueParameter<IntValue> PopulationSizeParameter {
      get { return (ValueParameter<IntValue>)Parameters[PopulationSizeParameterName]; }
    }
    public ValueParameter<DoubleValue> CrossoverProbabilityParameter {
      get { return (ValueParameter<DoubleValue>)Parameters[CrossoverProbabilityParameterName]; }
    }
    public ValueParameter<DoubleValue> ScalingFactorParameter {
      get { return (ValueParameter<DoubleValue>)Parameters[ScalingFactorParameterName]; }
    }
    public ValueParameter<DoubleValue> ValueToReachParameter {
      get { return (ValueParameter<DoubleValue>)Parameters[ValueToReachParameterName]; }
    }
    #endregion

    #region Properties
    public int MaximumEvaluations {
      get { return MaximumEvaluationsParameter.Value.Value; }
      set { MaximumEvaluationsParameter.Value.Value = value; }
    }

    public Double CrossoverProbability {
      get { return CrossoverProbabilityParameter.Value.Value; }
      set { CrossoverProbabilityParameter.Value.Value = value; }
    }
    public Double ScalingFactor {
      get { return ScalingFactorParameter.Value.Value; }
      set { ScalingFactorParameter.Value.Value = value; }
    }
    public int Seed {
      get { return SeedParameter.Value.Value; }
      set { SeedParameter.Value.Value = value; }
    }
    public bool SetSeedRandomly {
      get { return SetSeedRandomlyParameter.Value.Value; }
      set { SetSeedRandomlyParameter.Value.Value = value; }
    }
    public IntValue PopulationSize {
      get { return PopulationSizeParameter.Value; }
      set { PopulationSizeParameter.Value = value; }
    }
    public Double ValueToReach {
      get { return ValueToReachParameter.Value.Value; }
      set { ValueToReachParameter.Value.Value = value; }
    }
    #endregion

    #region ResultsProperties
    private double ResultsBestQuality {
      get { return ((DoubleValue)Results["Best Quality"].Value).Value; }
      set { ((DoubleValue)Results["Best Quality"].Value).Value = value; }
    }

    private double VTRBestQuality {
      get { return ((DoubleValue)Results["VTR"].Value).Value; }
      set { ((DoubleValue)Results["VTR"].Value).Value = value; }
    }

    private RealVector ResultsBestSolution {
      get { return (RealVector)Results["Best Solution"].Value; }
      set { Results["Best Solution"].Value = value; }
    }

    private int ResultsEvaluations {
      get { return ((IntValue)Results["Evaluations"].Value).Value; }
      set { ((IntValue)Results["Evaluations"].Value).Value = value; }
    }
    private int ResultsIterations {
      get { return ((IntValue)Results["Iterations"].Value).Value; }
      set { ((IntValue)Results["Iterations"].Value).Value = value; }
    }

    private DataTable ResultsQualities {
      get { return ((DataTable)Results["Qualities"].Value); }
    }
    private DataRow ResultsQualitiesBest {
      get { return ResultsQualities.Rows["Best Quality"]; }
    }

    #endregion

    [StorableConstructor]
    protected DifferentialEvolution(bool deserializing) : base(deserializing) { }

    protected DifferentialEvolution(DifferentialEvolution original, Cloner cloner)
      : base(original, cloner) {
    }

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

    public DifferentialEvolution() {
      Parameters.Add(new FixedValueParameter<IntValue>(MaximumEvaluationsParameterName, "", new IntValue(Int32.MaxValue)));
      Parameters.Add(new FixedValueParameter<IntValue>(SeedParameterName, "The random seed used to initialize the new pseudo random number generator.", new IntValue(0)));
      Parameters.Add(new FixedValueParameter<BoolValue>(SetSeedRandomlyParameterName, "True if the random seed should be set to a random value, otherwise false.", new BoolValue(true)));
      Parameters.Add(new ValueParameter<IntValue>(PopulationSizeParameterName, "The size of the population of solutions.", new IntValue(100)));
      Parameters.Add(new ValueParameter<DoubleValue>(CrossoverProbabilityParameterName, "The value for crossover rate", new DoubleValue(0.88)));
      Parameters.Add(new ValueParameter<DoubleValue>(ScalingFactorParameterName, "The value for scaling factor", new DoubleValue(0.47)));
      Parameters.Add(new ValueParameter<DoubleValue>(ValueToReachParameterName, "Value to reach (VTR) parameter", new DoubleValue(0.00000001)));
    }

    protected override void Run(CancellationToken cancellationToken) {

      // Set up the results display
      Results.Add(new Result("Iterations", new IntValue(0)));
      Results.Add(new Result("Evaluations", new IntValue(0)));
      Results.Add(new Result("Best Solution", new RealVector()));
      Results.Add(new Result("Best Quality", new DoubleValue(double.NaN)));
      Results.Add(new Result("VTR", new DoubleValue(double.NaN)));
      var table = new DataTable("Qualities");
      table.Rows.Add(new DataRow("Best Quality"));
      Results.Add(new Result("Qualities", table));


      //problem variables
      var dim = Problem.ProblemSize.Value;
      var lb = Problem.Bounds[0, 0];
      var ub = Problem.Bounds[0, 1];
      var range = ub - lb;
      this.evals = 0;

      double[,] populationOld = new double[PopulationSizeParameter.Value.Value, Problem.ProblemSize.Value];
      double[,] mutationPopulation = new double[PopulationSizeParameter.Value.Value, Problem.ProblemSize.Value];
      double[,] trialPopulation = new double[PopulationSizeParameter.Value.Value, Problem.ProblemSize.Value];
      double[] bestPopulation = new double[Problem.ProblemSize.Value];
      double[] bestPopulationIteration = new double[Problem.ProblemSize.Value];

      //create initial population 
      //population is a matrix of size PopulationSize*ProblemSize
      for(int i = 0; i < PopulationSizeParameter.Value.Value; i++) {
        for(int j = 0; j < Problem.ProblemSize.Value; j++) {
          populationOld[i, j] = _random.NextDouble() * range + lb;
        }
      }

      //evaluate the best member after the intialiazation
      //the idea is to select first member and after that to check the others members from the population

      int best_index = 0;
      double[] populationRow = new double[Problem.ProblemSize.Value];
      double[] qualityPopulation = new double[PopulationSizeParameter.Value.Value];
      bestPopulation = getMatrixRow(populationOld, best_index);
      RealVector bestPopulationVector = new RealVector(bestPopulation);
      double bestPopulationValue = Obj(bestPopulationVector);
      qualityPopulation[best_index] = bestPopulationValue;
      RealVector selectionVector;
      RealVector trialVector;
      double qtrial;


      for(var i = 1; i < PopulationSizeParameter.Value.Value; i++) {
        populationRow = getMatrixRow(populationOld, i);
        trialVector = new RealVector(populationRow);

        qtrial = Obj(trialVector);
        qualityPopulation[i] = qtrial;

        if(qtrial > bestPopulationValue) {
          bestPopulationVector = new RealVector(populationRow);
          bestPopulationValue = qtrial;
          best_index = i;
        }
      }

      int iterations = 1;

      // Loop until iteration limit reached or canceled.
      // todo replace with a function
      // && bestPopulationValue > Problem.BestKnownQuality.Value + ValueToReachParameter.Value.Value
      while(ResultsEvaluations < MaximumEvaluations
          && !cancellationToken.IsCancellationRequested
          && (bestPopulationValue - Problem.BestKnownQuality.Value) > ValueToReachParameter.Value.Value) {
        //mutation DE/rand/1/bin; classic DE
        for(int i = 0; i < PopulationSizeParameter.Value.Value; i++) {
          int r0, r1, r2;

          //assure the selected vectors r0, r1 and r2 are different
          do {
            r0 = _random.Next(0, PopulationSizeParameter.Value.Value);
          } while(r0 == i);
          do {
            r1 = _random.Next(0, PopulationSizeParameter.Value.Value);
          } while(r1 == i || r1 == r0);
          do {
            r2 = _random.Next(0, PopulationSizeParameter.Value.Value);
          } while(r2 == i || r2 == r0 || r2 == r1);

          for(int j = 0; j < getMatrixRow(mutationPopulation, i).Length; j++) {
            mutationPopulation[i, j] = populationOld[r0, j] +
                ScalingFactorParameter.Value.Value * (populationOld[r1, j] - populationOld[r2, j]);
            //check the problem upper and lower bounds
            if(mutationPopulation[i, j] > ub) mutationPopulation[i, j] = ub;
            if(mutationPopulation[i, j] < lb) mutationPopulation[i, j] = lb;
          }
        }

        //uniform crossover
        for(int i = 0; i < PopulationSizeParameter.Value.Value; i++) {
          double rnbr = _random.Next(0, Problem.ProblemSize.Value);
          for(int j = 0; j < getMatrixRow(mutationPopulation, i).Length; j++) {
            if(_random.NextDouble() <= CrossoverProbabilityParameter.Value.Value || j == rnbr) {
              trialPopulation[i, j] = mutationPopulation[i, j];
            } else {
              trialPopulation[i, j] = populationOld[i, j];
            }
          }
        }

        //One-to-One Survivor Selection
        for(int i = 0; i < PopulationSizeParameter.Value.Value; i++) {
          selectionVector = new RealVector(getMatrixRow(populationOld, i));
          trialVector = new RealVector(getMatrixRow(trialPopulation, i));

          var selectionEval = qualityPopulation[i];
          var trialEval = Obj(trialVector);

          if(trialEval < selectionEval) {
            for(int j = 0; j < getMatrixRow(populationOld, i).Length; j++) {
              populationOld[i, j] = trialPopulation[i, j];
            }
            qualityPopulation[i] = trialEval;
          }
        }

        //update the best candidate
        for(int i = 0; i < PopulationSizeParameter.Value.Value; i++) {
          selectionVector = new RealVector(getMatrixRow(populationOld, i));
          var quality = qualityPopulation[i];
          if(quality < bestPopulationValue) {
            bestPopulationVector = (RealVector)selectionVector.Clone();
            bestPopulationValue = quality;
          }
        }

        iterations = iterations + 1;

        //update the results
        ResultsEvaluations = evals;
        ResultsIterations = iterations;
        ResultsBestSolution = bestPopulationVector;
        ResultsBestQuality = bestPopulationValue;

        //update the results in view
        if(iterations % 10 == 0) ResultsQualitiesBest.Values.Add(bestPopulationValue);
        if(bestPopulationValue < Problem.BestKnownQuality.Value + ValueToReachParameter.Value.Value) {
          VTRBestQuality = bestPopulationValue;
        }
      }
    }

    public override bool SupportsPause { get { return false; } } // XXX is pause actually supported?

    //evaluate the vector
    public double Obj(RealVector x) {
      evals = evals + 1;
      if(Problem.Maximization.Value)
        return -Problem.Evaluator.Evaluate(x);

      return Problem.Evaluator.Evaluate(x);
    }

    // Get ith row from the matrix
    public double[] getMatrixRow(double[,] Mat, int i) {
      double[] tmp = new double[Mat.GetUpperBound(1) + 1];

      for(int j = 0; j <= Mat.GetUpperBound(1); j++) {
        tmp[j] = Mat[i, j];
      }

      return tmp;
    }
  }
}