#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2017 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.Diagnostics;
using System.Linq;
using System.Threading;
using HeuristicLab.Analysis;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Problems.GeneralizedQuadraticAssignment.Algorithms {
  [Item("Context-based Algorithm", "Algorithms that make use of contexts to facilitate applying operators.")]
  [StorableClass]
  public abstract class ContextAlgorithm<TContext, TEncoding> : BasicAlgorithm
    where TContext : class, IContext, new()
    where TEncoding : class, IEncoding {

    public override Type ProblemType {
      get { return typeof(SingleObjectiveBasicProblem<TEncoding>); }
    }

    public new SingleObjectiveBasicProblem<TEncoding> Problem {
      get { return (SingleObjectiveBasicProblem<TEncoding>)base.Problem; }
      set { base.Problem = value; }
    }

    [Storable]
    private TContext context;
    public TContext Context {
      get { return context; }
    }

    [Storable]
    private ValueParameter<IAnalyzer> analyzerParameter;
    public IValueParameter<IAnalyzer> AnalyzerParameter {
      get { return analyzerParameter; }
    }
    [Storable]
    private FixedValueParameter<IntValue> maximumIterationsParameter;
    public IFixedValueParameter<IntValue> MaximumIterationsParameter {
      get { return maximumIterationsParameter; }
    }
    [Storable]
    private FixedValueParameter<IntValue> maximumEvaluationsParameter;
    public IFixedValueParameter<IntValue> MaximumEvaluationsParameter {
      get { return maximumEvaluationsParameter; }
    }
    [Storable]
    private FixedValueParameter<TimeSpanValue> maximumRuntimeParameter;
    public IFixedValueParameter<TimeSpanValue> MaximumRuntimeParameter {
      get { return maximumRuntimeParameter; }
    }
    [Storable]
    private FixedValueParameter<BoolValue> stopAtBestKnownQualityParameter;
    public IFixedValueParameter<BoolValue> StopAtBestKnownQualityParameter {
      get { return stopAtBestKnownQualityParameter; }
    }

    public IAnalyzer Analyzer {
      get { return analyzerParameter.Value; }
      set { analyzerParameter.Value = value; }
    }
    public int MaximumIterations {
      get { return maximumIterationsParameter.Value.Value; }
      set { maximumIterationsParameter.Value.Value = value; }
    }
    public int MaximumEvaluations {
      get { return maximumEvaluationsParameter.Value.Value; }
      set { maximumEvaluationsParameter.Value.Value = value; }
    }
    public TimeSpan MaximumRuntime {
      get { return maximumRuntimeParameter.Value.Value; }
      set { maximumRuntimeParameter.Value.Value = value; }
    }
    public bool StopAtBestKnownQuality {
      get { return stopAtBestKnownQualityParameter.Value.Value; }
      set { stopAtBestKnownQualityParameter.Value.Value = value; }
    }

    private Stopwatch stopwatch;
    [Storable]
    private TimeSpan elapsed;
    [Storable]
    private IndexedDataTable<double> qualityPerClock;
    [Storable]
    private IndexedDataRow<double> firstHitGraph;

    [StorableConstructor]
    protected ContextAlgorithm(bool deserializing) : base(deserializing) { }
    protected ContextAlgorithm(ContextAlgorithm<TContext, TEncoding> original, Cloner cloner)
      : base(original, cloner) {
      context = cloner.Clone(original.context);
      analyzerParameter = cloner.Clone(original.analyzerParameter);
      maximumIterationsParameter = cloner.Clone(original.maximumIterationsParameter);
      maximumEvaluationsParameter = cloner.Clone(original.maximumEvaluationsParameter);
      maximumRuntimeParameter = cloner.Clone(original.maximumRuntimeParameter);
      stopAtBestKnownQualityParameter = cloner.Clone(original.stopAtBestKnownQualityParameter);
      elapsed = original.elapsed;
      qualityPerClock = cloner.Clone(original.qualityPerClock);
      firstHitGraph = cloner.Clone(original.firstHitGraph);
      if (context != null)
        context.BestQualityChanged += ContextOnBestQualityChanged;
    }
    protected ContextAlgorithm()
      : base() {
      Parameters.Add(analyzerParameter = new ValueParameter<IAnalyzer>("Analyzer", "The analyzers that are used to perform an analysis of the solutions.", new MultiAnalyzer()));
      Parameters.Add(maximumIterationsParameter = new FixedValueParameter<IntValue>("MaximumIterations", "The number of iterations that the algorithm should run or < 1 to ignore.", new IntValue(0)));
      Parameters.Add(maximumEvaluationsParameter = new FixedValueParameter<IntValue>("MaximumEvaluations", "The number of evaluated solutions that the algorithm should perform or < 1 to ignore.", new IntValue(0)));
      Parameters.Add(maximumRuntimeParameter = new FixedValueParameter<TimeSpanValue>("MaximumRuntime", "The timespan that the algorithm is allowed to run.", new TimeSpanValue(TimeSpan.FromMinutes(1))));
      Parameters.Add(stopAtBestKnownQualityParameter = new FixedValueParameter<BoolValue>("StopAtBestKnownQuality", "Whether the algorithm should terminate if the best known quality has been found.", new BoolValue(true)));
    }

    protected override void Initialize(CancellationToken cancellationToken) {
      base.Initialize(cancellationToken);
      context = new TContext();
      context.Scope.Variables.Add(new Variable("Results", Results));
      context.BestQualityChanged += ContextOnBestQualityChanged;

      IExecutionContext ctxt = null;
      foreach (var item in Problem.ExecutionContextItems)
        ctxt = new Core.ExecutionContext(ctxt, item, Context.Scope);
      ctxt = new Core.ExecutionContext(ctxt, this, Context.Scope);
      context.Parent = ctxt;

      context.Iterations = 0;
      context.EvaluatedSolutions = 0;
      context.BestQuality = double.NaN;

      qualityPerClock = new IndexedDataTable<double>("Quality Per Clock");
      firstHitGraph = new IndexedDataRow<double>("First-hit Graph");
      qualityPerClock.Rows.Add(firstHitGraph);
      Results.Add(new Result("QualityPerClock", qualityPerClock));

      elapsed = TimeSpan.Zero;
      stopwatch = Stopwatch.StartNew();
    }

    protected override void Run(CancellationToken cancellationToken) {
      if (stopwatch == null || !stopwatch.IsRunning) stopwatch = Stopwatch.StartNew();
    }

    private void ContextOnBestQualityChanged(object sender, EventArgs e) {
      if (double.IsNaN(Context.BestQuality)) return;
      var newEntry = Tuple.Create((elapsed + stopwatch.Elapsed).TotalSeconds, Context.BestQuality);

      if (firstHitGraph.Values.Count == 0) {
        firstHitGraph.Values.Add(newEntry); // record the first data
        firstHitGraph.Values.Add(Tuple.Create(newEntry.Item1, newEntry.Item2)); // last entry records max number of evaluations
        return;
      }

      var improvement = firstHitGraph.Values.Last().Item2 != newEntry.Item2;
      if (improvement) {
        firstHitGraph.Values[firstHitGraph.Values.Count - 1] = newEntry; // record the improvement
        firstHitGraph.Values.Add(Tuple.Create(newEntry.Item1, newEntry.Item2)); // last entry records max number of evaluations
      } else {
        firstHitGraph.Values[firstHitGraph.Values.Count - 1] = Tuple.Create(newEntry.Item1, newEntry.Item2);
      }
    }

    public override void Prepare() {
      if (context != null) {
        context.BestQualityChanged -= ContextOnBestQualityChanged;
        context = null;
      }
      base.Prepare();
    }

    protected override void OnPaused() {
      elapsed += stopwatch.Elapsed;
      stopwatch.Reset();
      firstHitGraph.Values[firstHitGraph.Values.Count - 1] = Tuple.Create(elapsed.TotalSeconds, Context.BestQuality);
      base.OnPaused();
    }

    protected override void OnStopped() {
      if (stopwatch.IsRunning) {
        elapsed += stopwatch.Elapsed;
        stopwatch.Reset();
        firstHitGraph.Values[firstHitGraph.Values.Count - 1] = Tuple.Create(elapsed.TotalSeconds, Context.BestQuality);
      }
      // base call must be done last as the results will be cloned and a run is created
      base.OnStopped();
    }

    [StorableHook(HookType.AfterDeserialization)]
    private void AfterDeserialization() {
      if (context != null) context.BestQualityChanged += ContextOnBestQualityChanged;
    }

    protected virtual bool StoppingCriterion() {
      return MaximumIterations > 0 && Context.Iterations > MaximumIterations
        || MaximumEvaluations > 0 && Context.EvaluatedSolutions > MaximumEvaluations
        || MaximumRuntime > TimeSpan.Zero && ExecutionTime > MaximumRuntime
        || StopAtBestKnownQuality && !double.IsNaN(Problem.BestKnownQuality)
          && Context.BestQuality.IsAlmost(Problem.BestKnownQuality);
    }
  }
}