#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.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> NeighborsBestQualityParameter {
      get { return (IScopeTreeLookupParameter<DoubleValue>)Parameters["NeighborsBestQuality"]; }
    }
    public IScopeTreeLookupParameter<RealVector> RealVectorParameter {
      get { return (IScopeTreeLookupParameter<RealVector>)Parameters["RealVector"]; }
    }
    public IScopeTreeLookupParameter<RealVector> PersonalBestParameter {
      get { return (IScopeTreeLookupParameter<RealVector>)Parameters["PersonalBest"]; }
    }
    public IScopeTreeLookupParameter<RealVector> NeighborsBestParameter {
      get { return (IScopeTreeLookupParameter<RealVector>)Parameters["NeighborsBest"]; }
    }
    public IValueLookupParameter<BoolValue> MaximizationParameter {
      get { return (IValueLookupParameter<BoolValue>)Parameters["Maximization"]; }
    }
    public ILookupParameter<DoubleValue> BestQualityParameter {
      get { return (ILookupParameter<DoubleValue>)Parameters["BestQuality"]; }
    }
    public ILookupParameter<RealVector> BestPointParameter {
      get { return (ILookupParameter<RealVector>)Parameters["BestPoint"]; }
    }
    public IScopeTreeLookupParameter<IntArray> NeighborsParameter {
      get { return (IScopeTreeLookupParameter<IntArray>)Parameters["Neighbors"]; }
    }
    #endregion

    #region Parameter values
    private DoubleValue BestQuality {
      get { return BestQualityParameter.ActualValue; }
    }
    private RealVector BestPoint {
      get { return BestPointParameter.ActualValue; }
      set { BestPointParameter.ActualValue = value; }
    }
    private ItemArray<DoubleValue> Quality {
      get { return QualityParameter.ActualValue; }
    }
    private ItemArray<DoubleValue> PersonalBestQuality {
      get { return PersonalBestQualityParameter.ActualValue; }
    }
    private ItemArray<DoubleValue> NeighborsBestQuality {
      get { return NeighborsBestQualityParameter.ActualValue; }
    }
    private ItemArray<RealVector> RealVector {
      get { return RealVectorParameter.ActualValue; }
    }
    private ItemArray<RealVector> PersonalBest {
      get { return PersonalBestParameter.ActualValue; }
      set { PersonalBestParameter.ActualValue = value; }
    }
    private ItemArray<RealVector> NeighborsBest {
      get { return NeighborsBestParameter.ActualValue; }
      set { NeighborsBestParameter.ActualValue = value; }
    }
    private bool Maximization {
      get { return MaximizationParameter.ActualValue.Value; }
    }
    private ItemArray<IntArray> Neighbors {
      get { return NeighborsParameter.ActualValue; }
    }
    #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>("BestPoint", "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>("NeighborsBestQuality", "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>("NeighborsBest", "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 ValueLookupParameter<BoolValue>("Maximization", "True if the problem is a maximization problem, otherwise false."));
    }

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

    #endregion

    public override IOperation Apply() {
      InitializeBestPoint();
      UpdateSwarm();
      UpdateNeighbors();
      UpdateVelocityBounds();
      return base.Apply();
    }

    private void InitializeBestPoint() {
      if (BestQuality == null)
        BestQualityParameter.ActualValue = new DoubleValue();
      BestQuality.Value = Maximization ? Quality.Max(v => v.Value) : Quality.Min(v => v.Value);
      int bestIndex = Quality.FindIndex(v => v.Value == BestQuality.Value);
      BestPoint = (RealVector)RealVector[bestIndex].Clone();
    }

    private void UpdateNeighbors() {
      if (Neighbors != null & Neighbors.Length > 0) {
        if (this.NeighborsBest == null || NeighborsBest.Length != Neighbors.Length)
          NeighborsBest = new ItemArray<RealVector>(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));
          NeighborsBest[n] = Maximization ?
          pairs.OrderByDescending(p => p.Quality.Value).First().Point :
          pairs.OrderBy(p => p.Quality.Value).First().Point;
        }
        NeighborsBestParameter.ActualValue = NeighborsBest;
      }
    }

    private void UpdateVelocityBounds() {
      // ToDo: Add code
    }

    private void UpdateSwarm() {
      if (PersonalBestQuality.Length == 0) {
        ItemArray<DoubleValue> personalBestQualities = new ItemArray<DoubleValue>(RealVector.Length);
        for (int i = 0; i < RealVector.Length; i++) {
          if (Maximization) {
            personalBestQualities[i] = new DoubleValue(double.MinValue);
          } else {
            personalBestQualities[i] = new DoubleValue(double.MaxValue);
          }
        }
        PersonalBestQualityParameter.ActualValue = personalBestQualities;
      }
      if (NeighborsBestQuality.Length == 0) {
        if (NeighborsParameter != null && Neighbors.Length > 0) {
          ItemArray<DoubleValue> neighborsBestQualities = new ItemArray<DoubleValue>(RealVector.Length);
          for (int i = 0; i < RealVector.Length; i++) {
            if (Maximization) {
              neighborsBestQualities[i] = new DoubleValue(double.MinValue);
            } else {
              neighborsBestQualities[i] = new DoubleValue(double.MaxValue);
            }
          }
          NeighborsBestQualityParameter.ActualValue = neighborsBestQualities;
        }
      }
      ItemArray<RealVector> neighborsBest = new ItemArray<RealVector>(RealVector.Length);
      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];
          if (Maximization && PersonalBestQuality[i].Value > NeighborsBestQuality[i].Value ||
             !Maximization && PersonalBestQuality[i].Value < NeighborsBestQuality[i].Value) {
            NeighborsBestQuality[i].Value = PersonalBestQuality[i].Value;
            neighborsBest[i] = PersonalBest[i];
          }
        }
      }
      if (NeighborsParameter != null && Neighbors.Length > 0) {
        NeighborsBestParameter.ActualValue = neighborsBest;
      }
    }

  }
}