#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2019 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 System.Threading;
using System.Threading.Tasks;
using HeuristicLab.Common;
using HeuristicLab.Data;
using HeuristicLab.MainForm;

namespace HeuristicLab.Problems.DataAnalysis.Views {
  [View("Variable Impacts")]
  [Content(typeof(IRegressionSolution))]
  public partial class RegressionSolutionVariableImpactsView : DataAnalysisSolutionEvaluationView {
    private enum SortingCriteria {
      ImpactValue,
      Occurrence,
      VariableName
    }
    private CancellationTokenSource cancellationToken = new CancellationTokenSource();
    private List<Tuple<string, double>> rawVariableImpacts = new List<Tuple<string, double>>();

    public new IRegressionSolution Content {
      get { return (IRegressionSolution)base.Content; }
      set {
        base.Content = value;
      }
    }

    public RegressionSolutionVariableImpactsView()
      : base() {
      InitializeComponent();

      //Set the default values
      this.dataPartitionComboBox.SelectedIndex = 0;
      this.replacementComboBox.SelectedIndex = 3;
      this.factorVarReplComboBox.SelectedIndex = 0;
      this.sortByComboBox.SelectedItem = SortingCriteria.ImpactValue;
    }

    protected override void RegisterContentEvents() {
      base.RegisterContentEvents();
      Content.ModelChanged += new EventHandler(Content_ModelChanged);
      Content.ProblemDataChanged += new EventHandler(Content_ProblemDataChanged);
    }
    protected override void DeregisterContentEvents() {
      base.DeregisterContentEvents();
      Content.ModelChanged -= new EventHandler(Content_ModelChanged);
      Content.ProblemDataChanged -= new EventHandler(Content_ProblemDataChanged);
    }

    protected virtual void Content_ProblemDataChanged(object sender, EventArgs e) {
      OnContentChanged();
    }
    protected virtual void Content_ModelChanged(object sender, EventArgs e) {
      OnContentChanged();
    }
    protected override void OnContentChanged() {
      base.OnContentChanged();
      rawVariableImpacts.Clear();

      if (Content == null) {
        variableImpactsArrayView.Content = null;
      } else {
        UpdateVariableImpact();
      }
    }
    private void RegressionSolutionVariableImpactsView_VisibleChanged(object sender, EventArgs e) {
      cancellationToken.Cancel();
    }

    private void dataPartitionComboBox_SelectedIndexChanged(object sender, EventArgs e) {
      rawVariableImpacts.Clear();
      UpdateVariableImpact();
    }
    private void replacementComboBox_SelectedIndexChanged(object sender, EventArgs e) {
      rawVariableImpacts.Clear();
      UpdateVariableImpact();
    }
    private void sortByComboBox_SelectedIndexChanged(object sender, EventArgs e) {
      //Update the default ordering (asc,desc), but remove the eventHandler beforehand (otherwise the data would be ordered twice)
      ascendingCheckBox.CheckedChanged -= ascendingCheckBox_CheckedChanged;
      ascendingCheckBox.Checked = (SortingCriteria)sortByComboBox.SelectedItem != SortingCriteria.ImpactValue;
      ascendingCheckBox.CheckedChanged += ascendingCheckBox_CheckedChanged;

      UpdateOrdering();
    }
    private void ascendingCheckBox_CheckedChanged(object sender, EventArgs e) {
      UpdateOrdering();
    }

    private async void UpdateVariableImpact() {
      //Check if the selection is valid
      if (Content == null) { return; }
      if (replacementComboBox.SelectedIndex < 0) { return; }
      if (dataPartitionComboBox.SelectedIndex < 0) { return; }
      if (factorVarReplComboBox.SelectedIndex < 0) { return; }

      //Prepare arguments
      var replMethod = (RegressionSolutionVariableImpactsCalculator.ReplacementMethodEnum)replacementComboBox.Items[replacementComboBox.SelectedIndex];
      var factorReplMethod = (RegressionSolutionVariableImpactsCalculator.FactorReplacementMethodEnum)factorVarReplComboBox.Items[factorVarReplComboBox.SelectedIndex];
      var dataPartition = (RegressionSolutionVariableImpactsCalculator.DataPartitionEnum)dataPartitionComboBox.SelectedItem;

      variableImpactsArrayView.Caption = Content.Name + " Variable Impacts";
      var progress = Progress.Show(this, "Calculating variable impacts for " + Content.Name);
      cancellationToken = new CancellationTokenSource();

      try {
        var problemData = Content.ProblemData;
        var inputvariables = new HashSet<string>(problemData.AllowedInputVariables.Union(Content.Model.VariablesUsedForPrediction));
        //Remember the original ordering of the variables
        var originalVariableOrdering = problemData.Dataset.VariableNames
          .Where(v => inputvariables.Contains(v))
          .Where(v => problemData.Dataset.VariableHasType<double>(v) || problemData.Dataset.VariableHasType<string>(v))
          .ToList();

        List<Tuple<string, double>> impacts = null;
        await Task.Run(() => { impacts = CalculateVariableImpacts(originalVariableOrdering, Content.Model, problemData, Content.EstimatedValues, dataPartition, replMethod, factorReplMethod, cancellationToken.Token, progress); });
        if (impacts == null) { return; }

        rawVariableImpacts.AddRange(impacts);
        UpdateOrdering();
      }
      finally {
        Progress.Hide(this);
      }
    }
    private List<Tuple<string, double>> CalculateVariableImpacts(List<string> originalVariableOrdering,
      IRegressionModel model,
      IRegressionProblemData problemData,
      IEnumerable<double> estimatedValues,
      RegressionSolutionVariableImpactsCalculator.DataPartitionEnum dataPartition,
      RegressionSolutionVariableImpactsCalculator.ReplacementMethodEnum replMethod,
      RegressionSolutionVariableImpactsCalculator.FactorReplacementMethodEnum factorReplMethod,
      CancellationToken token,
      IProgress progress) {
      List<Tuple<string, double>> impacts = new List<Tuple<string, double>>();
      int count = originalVariableOrdering.Count;
      int i = 0;
      var modifiableDataset = ((Dataset)(problemData.Dataset).Clone()).ToModifiable();
      IEnumerable<int> rows = RegressionSolutionVariableImpactsCalculator.GetPartitionRows(dataPartition, problemData);

      //Calculate original quality-values (via calculator, default is R²)
      IEnumerable<double> targetValuesPartition = problemData.Dataset.GetDoubleValues(problemData.TargetVariable, rows);
      IEnumerable<double> estimatedValuesPartition = Content.GetEstimatedValues(rows);

      var originalCalculatorValue = RegressionSolutionVariableImpactsCalculator.CalculateQuality(targetValuesPartition, estimatedValuesPartition);

      foreach (var variableName in originalVariableOrdering) {
        if (cancellationToken.Token.IsCancellationRequested) { return null; }
        progress.ProgressValue = (double)++i / count;
        progress.Message = string.Format("Calculating impact for variable {0} ({1} of {2})", variableName, i, count);

        double impact = 0;
        //If the variable isn't used for prediction, it has zero impact.
        if (model.VariablesUsedForPrediction.Contains(variableName)) {
          impact = RegressionSolutionVariableImpactsCalculator.CalculateImpact(variableName, model, problemData, modifiableDataset, rows, replMethod, factorReplMethod, targetValuesPartition, originalCalculatorValue);
        }
        impacts.Add(new Tuple<string, double>(variableName, impact));
      }

      return impacts;
    }

    /// <summary>
    /// Updates the <see cref="variableImpactsArrayView"/> according to the selected ordering <see cref="ascendingCheckBox"/> of the selected Column <see cref="sortByComboBox"/>
    /// The default is "Descending" by "VariableImpact" (as in previous versions)
    /// </summary>
    private void UpdateOrdering() {
      //Check if valid sortingCriteria is selected and data exists
      if (sortByComboBox.SelectedIndex == -1) { return; }
      if (rawVariableImpacts == null) { return; }
      if (!rawVariableImpacts.Any()) { return; }

      var selectedItem = (SortingCriteria)sortByComboBox.SelectedItem;
      bool ascending = ascendingCheckBox.Checked;

      IEnumerable<Tuple<string, double>> orderedEntries = null;

      //Sort accordingly
      switch (selectedItem) {
        case SortingCriteria.ImpactValue:
          orderedEntries = rawVariableImpacts.OrderBy(v => v.Item2);
          break;
        case SortingCriteria.Occurrence:
          orderedEntries = rawVariableImpacts;
          break;
        case SortingCriteria.VariableName:
          orderedEntries = rawVariableImpacts.OrderBy(v => v.Item1, new NaturalStringComparer());
          break;
        default:
          throw new NotImplementedException("Ordering for selected SortingCriteria not implemented");
      }

      if (!ascending) { orderedEntries = orderedEntries.Reverse(); }

      //Write the data back
      var impactArray = new DoubleArray(orderedEntries.Select(i => i.Item2).ToArray()) {
        ElementNames = orderedEntries.Select(i => i.Item1)
      };

      //Could be, if the View was closed
      if (!variableImpactsArrayView.IsDisposed) {
        variableImpactsArrayView.Content = (DoubleArray)impactArray.AsReadOnly();
      }
    }
  }
}