#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2010 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.Data;
using HeuristicLab.Encodings.RealVectorEncoding;
using HeuristicLab.Operators;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Analysis.FitnessLandscape {

  [Item("GridRealVectorsCreator", "An operator that creates solutions on a grid accross the whole solution space.")]
  [StorableClass]
  public sealed class GridRealVectorCreator : SingleSuccessorOperator {

    #region Parameters
    public ValueLookupParameter<IntValue> NumberOfSolutionsParameter {
      get { return (ValueLookupParameter<IntValue>)Parameters["NumberOfSolutions"]; }
    }
    public LookupParameter<IntValue> ProblemSizeParameter {
      get { return (LookupParameter<IntValue>)Parameters["ProblemSize"]; }
    }
    public ValueLookupParameter<DoubleMatrix> BoundsParameter {
      get { return (ValueLookupParameter<DoubleMatrix>)Parameters["Bounds"]; }
    }
    private ScopeParameter CurrentScopeParameter {
      get { return (ScopeParameter)Parameters["CurrentScope"]; }
    }
    public LookupParameter<IRandom> RandomParameter {
      get { return (LookupParameter<IRandom>)Parameters["Random"]; }
    }
    public LookupParameter<RealVector> RealVectorParameter {
      get { return (LookupParameter<RealVector>)Parameters["RealVector"]; }
    }
    #endregion

    #region Parameter Values
    public IScope CurrentScope {
      get { return CurrentScopeParameter.ActualValue; }
    }
    public int NumberOfSolutions {
      get { return NumberOfSolutionsParameter.ActualValue.Value; }
    }
    public DoubleMatrix Bounds {
      get { return BoundsParameter.ActualValue; }
    }
    public IRandom Random {
      get { return RandomParameter.ActualValue; }
    }
    public int ProblemSize {
      get { return ProblemSizeParameter.ActualValue.Value; }
    }
    #endregion

    #region Construction & Cloning
    [StorableConstructor]
    private GridRealVectorCreator(bool deserializing) : base(deserializing) { }
    private GridRealVectorCreator(GridRealVectorCreator original, Cloner cloner) : base(original, cloner) { }
    public GridRealVectorCreator()
      : base() {
      Parameters.Add(new ValueLookupParameter<IntValue>("NumberOfSolutions", "The number of solutions that should be created."));
      Parameters.Add(new ValueLookupParameter<DoubleMatrix>("Bounds", "The minimum and maximum values in each dimension."));
      Parameters.Add(new ScopeParameter("CurrentScope", "The current scope to which the new solutions are added as sub-scopes."));
      Parameters.Add(new LookupParameter<IRandom>("Random", "Random number generator for sampling large grids."));
      Parameters.Add(new LookupParameter<IntValue>("ProblemSize", "The number of dimensions"));
      Parameters.Add(new LookupParameter<RealVector>("RealVector", "The real vector to be created in every scope."));
      RealVectorParameter.ActualName = "Point";
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new GridRealVectorCreator(this, cloner);
    }
    #endregion

    public override IOperation Apply() {
      string realVectorName = RealVectorParameter.TranslatedName;
      int current = CurrentScope.SubScopes.Count;
      for (int i = 0; i < NumberOfSolutions; i++)
        CurrentScope.SubScopes.Add(new Scope((current + i).ToString()));
      double[] ranges = Enumerable.Range(0, Bounds.Rows).Select(i => Math.Abs(Bounds[i, 0]-Bounds[i, 1])).ToArray();
      double[] offsets = Enumerable.Range(0, Bounds.Rows).Select(i => Math.Min(Bounds[i, 0], Bounds[i, 1])).ToArray();
      foreach (RealVector vector in GenerateGridSample(ProblemSize, NumberOfSolutions)) {
        for (int i = 0; i<ProblemSize; i++) {
          vector[i] = vector[i] * ranges[i % ranges.Length] + offsets[i % ranges.Length];
        }
        CurrentScope.SubScopes[current].Variables.Add(new Variable(realVectorName, vector));
        current++;
      }
      return base.Apply();
    }

    public IEnumerable<RealVector> GenerateGridSample(int nDim, int nVectors) {
      int nPoints = (int)Math.Max(Math.Ceiling(Math.Pow(nVectors, 1.0/nDim)), 3);
      double nPossibleSamples = Math.Pow(nPoints, nDim);
      if (nVectors > nPossibleSamples)
        throw new InvalidOperationException(string.Format("Number of samples ({0}) exceeds number of possible samples ({1})", nVectors, nPossibleSamples));
      if (nPossibleSamples < nVectors * 2) {
        if (nPossibleSamples > (double)int.MaxValue)
          throw new InvalidOperationException("Cannot exhaustivly generate more than int.MaxValue samples");
        List<RealVector> vectors = new List<RealVector>();
        for (int i = 0; i<nPossibleSamples; i++) {
          RealVector newVector = new RealVector(nDim);
          int index = i;
          for (int j = 0; j<nDim; j++) {
            newVector[j] = 1.0 * (index % nPoints) / (nPoints-1);
            index /= nPoints;
          }
          vectors.Add(newVector);
        }
        while (vectors.Count > nVectors) {
          vectors.RemoveAt(Random.Next(vectors.Count));
        }
        return vectors;
      } else {
        HashSet<RealVector> vectors = new HashSet<RealVector>();
        while (vectors.Count < nVectors) {
          RealVector newVector = new RealVector(nDim);
          for (int i = 0; i<nDim; i++) {
            newVector[i] = 1.0 * Random.Next(nPoints) / (nPoints-1);
          }
          vectors.Add(newVector);
        }
        return vectors;
      }
    }
  }
}