#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2011 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.Linq;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Operators;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Encodings.RealVectorEncoding {
  [Item("Swarm Updater", "Updates personal best point and quality as well as global best point and quality.")]
  [StorableClass]
  public sealed class RealVectorSwarmUpdater : SingleSuccessorOperator, IRealVectorSwarmUpdater {

    public override bool CanChangeName {
      get { return false; }
    }

    #region Parameter properties
    public IScopeTreeLookupParameter<DoubleValue> QualityParameter {
      get { return (IScopeTreeLookupParameter<DoubleValue>)Parameters["Quality"]; }
    }
    public IScopeTreeLookupParameter<DoubleValue> PersonalBestQualityParameter {
      get { return (IScopeTreeLookupParameter<DoubleValue>)Parameters["PersonalBestQuality"]; }
    }
    public IScopeTreeLookupParameter<DoubleValue> NeighborBestQualityParameter {
      get { return (IScopeTreeLookupParameter<DoubleValue>)Parameters["NeighborBestQuality"]; }
    }
    public IScopeTreeLookupParameter<RealVector> RealVectorParameter {
      get { return (IScopeTreeLookupParameter<RealVector>)Parameters["RealVector"]; }
    }
    public IScopeTreeLookupParameter<RealVector> PersonalBestParameter {
      get { return (IScopeTreeLookupParameter<RealVector>)Parameters["PersonalBest"]; }
    }
    public IScopeTreeLookupParameter<RealVector> NeighborBestParameter {
      get { return (IScopeTreeLookupParameter<RealVector>)Parameters["NeighborBest"]; }
    }
    public ILookupParameter<BoolValue> MaximizationParameter {
      get { return (ILookupParameter<BoolValue>)Parameters["Maximization"]; }
    }
    public ILookupParameter<DoubleValue> BestQualityParameter {
      get { return (ILookupParameter<DoubleValue>)Parameters["BestQuality"]; }
    }
    public ILookupParameter<RealVector> BestRealVectorParameter {
      get { return (ILookupParameter<RealVector>)Parameters["BestRealVector"]; }
    }
    public IScopeTreeLookupParameter<IntArray> NeighborsParameter {
      get { return (IScopeTreeLookupParameter<IntArray>)Parameters["Neighbors"]; }
    }
    public ValueLookupParameter<IDiscreteDoubleMatrixModifier> VelocityBoundsUpdaterParameter {
      get { return (ValueLookupParameter<IDiscreteDoubleMatrixModifier>)Parameters["VelocityBoundsUpdater"]; }
    }
    public LookupParameter<DoubleMatrix> VelocityBoundsParameter {
      get { return (LookupParameter<DoubleMatrix>)Parameters["VelocityBounds"]; }
    }
    #endregion

    #region Parameter values
    private DoubleValue BestQuality {
      get { return BestQualityParameter.ActualValue; }
      set { BestQualityParameter.ActualValue = value; }
    }
    private RealVector BestRealVector {
      get { return BestRealVectorParameter.ActualValue; }
      set { BestRealVectorParameter.ActualValue = value; }
    }
    private ItemArray<DoubleValue> Quality {
      get { return QualityParameter.ActualValue; }
    }
    private ItemArray<DoubleValue> PersonalBestQuality {
      get { return PersonalBestQualityParameter.ActualValue; }
      set { PersonalBestQualityParameter.ActualValue = value; }
    }
    private ItemArray<DoubleValue> NeighborBestQuality {
      get { return NeighborBestQualityParameter.ActualValue; }
      set { NeighborBestQualityParameter.ActualValue = value; }
    }
    private ItemArray<RealVector> RealVector {
      get { return RealVectorParameter.ActualValue; }
    }
    private ItemArray<RealVector> PersonalBest {
      get { return PersonalBestParameter.ActualValue; }
      set { PersonalBestParameter.ActualValue = value; }
    }
    private ItemArray<RealVector> NeighborBest {
      get { return NeighborBestParameter.ActualValue; }
      set { NeighborBestParameter.ActualValue = value; }
    }
    private bool Maximization {
      get { return MaximizationParameter.ActualValue.Value; }
    }
    private ItemArray<IntArray> Neighbors {
      get { return NeighborsParameter.ActualValue; }
    }
    private IDiscreteDoubleMatrixModifier VelocityBoundsUpdater {
      get { return VelocityBoundsUpdaterParameter.ActualValue; }
    }
    private DoubleMatrix VelocityBounds {
      get { return VelocityBoundsParameter.ActualValue; }
      set { VelocityBoundsParameter.ActualValue = value; }
    }
    #endregion

    #region Construction & Cloning

    [StorableConstructor]
    private RealVectorSwarmUpdater(bool deserializing) : base(deserializing) { }
    private RealVectorSwarmUpdater(RealVectorSwarmUpdater original, Cloner cloner) : base(original, cloner) { }
    public RealVectorSwarmUpdater()
      : base() {
      Parameters.Add(new LookupParameter<DoubleValue>("BestQuality", "Overall best quality."));
      Parameters.Add(new LookupParameter<RealVector>("BestRealVector", "Global best particle position"));
      Parameters.Add(new ScopeTreeLookupParameter<DoubleValue>("Quality", "Particle's quality"));
      Parameters.Add(new ScopeTreeLookupParameter<DoubleValue>("PersonalBestQuality", "Particle's personal best quality"));
      Parameters.Add(new ScopeTreeLookupParameter<DoubleValue>("NeighborBestQuality", "Global best particle quality"));
      Parameters.Add(new ScopeTreeLookupParameter<RealVector>("RealVector", "Particle's position"));
      Parameters.Add(new ScopeTreeLookupParameter<RealVector>("PersonalBest", "Particle's personal best position"));
      Parameters.Add(new ScopeTreeLookupParameter<RealVector>("NeighborBest", "Neighborhood (or global in case of totally connected neighborhood) best particle position"));
      Parameters.Add(new ScopeTreeLookupParameter<IntArray>("Neighbors", "The list of neighbors for each particle."));
      Parameters.Add(new LookupParameter<BoolValue>("Maximization", "True if the problem is a maximization problem, otherwise false."));
      Parameters.Add(new ValueLookupParameter<IDiscreteDoubleMatrixModifier>("VelocityBoundsUpdater", "Modifies the velocity bounds in the course of optimization."));
      Parameters.Add(new LookupParameter<DoubleMatrix>("VelocityBounds", "Maximum velocity for each dimension."));
    }

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

    #endregion

    public override IOperation Apply() {
      UpdateGlobalBest();
      UpdateNeighborBest();
      UpdatePersonalBest();
      return UpdateVelocityBounds();
    }

    private void UpdateGlobalBest() {
      if (BestQuality == null)
        BestQuality = new DoubleValue();
      BestQuality.Value = Maximization ? Quality.Max(v => v.Value) : Quality.Min(v => v.Value);
      BestRealVector = (RealVector)RealVector[Quality.FindIndex(v => v.Value == BestQuality.Value)].Clone();
    }

    private void UpdateNeighborBest() {
      if (Neighbors.Length > 0) {
        var neighborBest = new ItemArray<RealVector>(Neighbors.Length);
        var neighborBestQuality = new ItemArray<DoubleValue>(Neighbors.Length);
        for (int n = 0; n < Neighbors.Length; n++) {
          var pairs = Quality.Zip(RealVector, (q, p) => new { Quality = q, Point = p })
            .Where((p, i) => i == n || Neighbors[n].Contains(i));
          var bestNeighbor = Maximization ?
            pairs.OrderByDescending(p => p.Quality.Value).First() :
            pairs.OrderBy(p => p.Quality.Value).First();
          neighborBest[n] = bestNeighbor.Point;
          neighborBestQuality[n] = bestNeighbor.Quality;
        }
        NeighborBest = neighborBest;
        NeighborBestQuality = neighborBestQuality;
      }
    }

    private void UpdatePersonalBest() {
      if (PersonalBestQuality.Length == 0)
        PersonalBestQuality = (ItemArray<DoubleValue>)Quality.Clone();
      for (int i = 0; i < RealVector.Length; i++) {
        if (Maximization && Quality[i].Value > PersonalBestQuality[i].Value ||
          !Maximization && Quality[i].Value < PersonalBestQuality[i].Value) {
          PersonalBestQuality[i].Value = Quality[i].Value;
          PersonalBest[i] = RealVector[i];
        }
      }
    }

    private IOperation UpdateVelocityBounds() {
      if (VelocityBounds == null)
        VelocityBounds = new DoubleMatrix(new double[,] { { -1, 1 } });
      return VelocityBoundsUpdater == null ?
        base.Apply() :
        new OperationCollection() { 
          ExecutionContext.CreateChildOperation(VelocityBoundsUpdater),
          ExecutionContext.CreateOperation(Successor)
        };
    }
  }
}