#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 * and the BEACON Center for the Study of Evolution in Action.
 * 
 * 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.Threading;
using HeuristicLab.Analysis;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.PluginInfrastructure;
using HeuristicLab.Random;

namespace HeuristicLab.Algorithms.IteratedSymbolicExpressionConstruction {
  [Item("Iterated Symbolic Expression Construction", "Generates symbolic expression trees iteratively.")]
  [StorableClass]
  [Creatable(CreatableAttribute.Categories.SingleSolutionAlgorithms, Priority = 400)]
  public class IteratedSymbolicExpressionConstruction : BasicAlgorithm {
    public override Type ProblemType {
      get { return typeof(SymbolicExpressionTreeProblem); }
    }
    public new SymbolicExpressionTreeProblem Problem {
      get { return (SymbolicExpressionTreeProblem)base.Problem; }
      set { base.Problem = value; }
    }

    #region ParameterNames
    private const string MaximumEvaluationsParameterName = "Maximum Evaluations";
    private const string SeedParameterName = "Seed";
    private const string SetSeedRandomlyParameterName = "SetSeedRandomly";
    private const string ResultUpdateIntervalParameterName = "ResultUpdateInterval";
    private const string PolicyParameterName = "Policy";
    #endregion

    #region ParameterProperties
    public IFixedValueParameter<IntValue> MaximumEvaluationsParameter {
      get { return (IFixedValueParameter<IntValue>)Parameters[MaximumEvaluationsParameterName]; }
    }
    public IFixedValueParameter<IntValue> SeedParameter {
      get { return (IFixedValueParameter<IntValue>)Parameters[SeedParameterName]; }
    }
    public IFixedValueParameter<BoolValue> SetSeedRandomlyParameter {
      get { return (IFixedValueParameter<BoolValue>)Parameters[SetSeedRandomlyParameterName]; }
    }
    public IFixedValueParameter<IntValue> ResultUpdateIntervalParameter {
      get { return (IFixedValueParameter<IntValue>)Parameters[ResultUpdateIntervalParameterName]; }
    }
    public IValueParameter<ISymbolicExpressionConstructionPolicy> PolicyParameter {
      get {
        return (IValueParameter<ISymbolicExpressionConstructionPolicy>)Parameters[PolicyParameterName];
      }
    }
    #endregion

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

    #region ResultsProperties
    public double ResultsBestQuality {
      get { return ((DoubleValue)Results["Best Quality"].Value).Value; }
    }
    public int ResultsBestFoundOnEvaluation {
      get { return ((IntValue)Results["Evaluation Best Solution Was Found"].Value).Value; }
    }
    public int ResultsEvaluations {
      get { return ((IntValue)Results["Evaluations"].Value).Value; }
    }
    public DataTable ResultsQualities {
      get { return ((DataTable)Results["Qualities"].Value); }
    }
    public DataRow ResultsQualitiesBest {
      get { return ResultsQualities.Rows["Best Quality"]; }
    }
    public DataRow ResultQualitiesAverage {
      get { return ResultsQualities.Rows["Average Quality"]; }
    }
    #endregion

    private readonly IRandom random = new MersenneTwister();


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

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

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

    public IteratedSymbolicExpressionConstruction() {
      Parameters.Add(new FixedValueParameter<IntValue>(MaximumEvaluationsParameterName, "", new IntValue(500000)));
      Parameters.Add(new FixedValueParameter<IntValue>(ResultUpdateIntervalParameterName, "The update interval for the result values in number of evaluations", new IntValue(100)));
      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<ISymbolicExpressionConstructionPolicy>(PolicyParameterName, "The policy to use for exploring the search tree", new UcbSymbolicExpressionConstructionPolicy()));
    }

    protected override void Run(CancellationToken cancellationToken) {
      // TODO minimization problems
      if (!Problem.Maximization) throw new NotSupportedException("Minimization problems are not supported");

      // Set up the algorithm
      if (SetSeedRandomly) Seed = new System.Random().Next();
      random.Reset(Seed);

      var policy = PolicyParameter.Value;
      policy.Initialize(Problem, random);

      IntValue evaluations = new IntValue(0);
      DoubleValue bestQuality = new DoubleValue(Double.NegativeInfinity);
      IntValue bestFoundOnEvaluation = new IntValue(0);

      // Set up the results display
      Results.Add(new Result("Evaluations", evaluations));
      Results.Add(new Result("Best Quality", bestQuality));
      Results.Add(new Result("Evaluation Best Solution Was Found", bestFoundOnEvaluation));

      var table = new DataTable("Qualities");
      var bestQualityRow = new DataRow("Best Quality");
      table.Rows.Add(bestQualityRow);

      var currentQualityRow = new DataRow("Average Quality");
      currentQualityRow.VisualProperties.LineStyle = DataRowVisualProperties.DataRowLineStyle.Dot;
      table.Rows.Add(currentQualityRow);

      Results.Add(new Result("Qualities", table));

      // for problem-specific analyzer
      ISymbolicExpressionTree[] solutions = new ISymbolicExpressionTree[1];
      double[] qualities = new double[1];

      // the algorithm
      // Loop until iteration limit reached or canceled.
      int evals = 0;
      double sumQuality = 0; // for average quality calculation
      int resultUpdateInterval = ResultUpdateInterval;
      try {
        while (evals < MaximumEvaluations) {
          double quality = double.NaN;
          ISymbolicExpressionTree tree = null;
          IEnumerable<object> stateSequence;
          tree = policy.Sample(out stateSequence);
          quality = Problem.Evaluate(tree, random);
          evals++;
          sumQuality += quality;

          policy.Update(stateSequence, quality);
          cancellationToken.ThrowIfCancellationRequested();

          // update statistics results in regular update intervals
          if ((evals - 1) % resultUpdateInterval == resultUpdateInterval - 1) {
            evaluations.Value = evals;
            bestQualityRow.Values.Add(bestQuality.Value);
            currentQualityRow.Values.Add(sumQuality / (double)resultUpdateInterval);
            sumQuality = 0;
          }

          // update best solution results whenever a new better solution is found
          if (Problem.IsBetter(quality, bestQuality.Value)) {
            bestQuality.Value = quality;
            bestFoundOnEvaluation.Value = evals;

            // for problem-specific analyzer
            solutions[0] = tree;
            qualities[0] = quality;
          }

          // run problem-specific analyzer in each iteration
          Problem.Analyze(solutions, qualities, Results, random);
        }
      } finally {
        // update stats whenever the alg is stopped
        evaluations.Value = evals;
        bestQualityRow.Values.Add(bestQuality.Value);
        currentQualityRow.Values.Add(sumQuality / (double)resultUpdateInterval);
      }
    }

  }
}