#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2013 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;
using System.Collections.Generic;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Problems.DataAnalysis;
using HeuristicLab.Problems.DataAnalysis.Transformations;

namespace HeuristicLab.DataPreprocessing {

  internal class Snapshot {
    public IList<IList> VariableValues { get; set; }

    public IList<string> VariableNames { get; set; }

    public double TrainingToTestRatio { get; set; }

    public IList<ITransformation> Transformations { get; set; }

    public DataPreprocessingChangedEventType ChangedType { get; set; }

    public int ChangedColumn { get; set; }

    public int ChangedRow { get; set; }
  }

  [Item("PreprocessingData", "Represents data used for preprocessing.")]
  public class TransactionalPreprocessingData : PreprocessingData, ITransactionalPreprocessingData {

    private const int MAX_UNDO_DEPTH = 5;

    private IList<Snapshot> undoHistory;

    private Stack<DataPreprocessingChangedEventType> eventStack = new Stack<DataPreprocessingChangedEventType>();

    private DataPreprocessingChangedEventType lastOccuredChangedType = DataPreprocessingChangedEventType.Any;

    public bool IsInTransaction { get { return eventStack.Count > 0; } }

    public TransactionalPreprocessingData(IDataAnalysisProblemData problemData)
      : base(problemData) {
      undoHistory = new List<Snapshot>();
    }

    private TransactionalPreprocessingData(TransactionalPreprocessingData original, Cloner cloner)
      : base(original, cloner) {
      undoHistory = new List<Snapshot>();
    }

    private void SaveSnapshot(DataPreprocessingChangedEventType changedType, int column, int row) {
      if (eventStack.Count > 0) return;

      var currentSnapshot = new Snapshot {
        VariableValues = CopyVariableValues(variableValues),
        VariableNames = new List<string>(variableNames),
        TrainingToTestRatio = trainingToTestRatio,
        Transformations = new List<ITransformation>(transformations),
        ChangedType = changedType,
        ChangedColumn = column,
        ChangedRow = row
      };

      if (undoHistory.Count >= MAX_UNDO_DEPTH)
        undoHistory.RemoveAt(0);

      undoHistory.Add(currentSnapshot);
    }

    #region NamedItem abstract Member Implementations

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

    #endregion

    #region Overridden IPreprocessingData Members

    public override void SetCell<T>(int columnIndex, int rowIndex, T value) {
      SaveSnapshot(DataPreprocessingChangedEventType.ChangeItem, columnIndex, rowIndex);
      base.SetCell<T>(columnIndex, rowIndex, value);
      if (!IsInTransaction)
        OnChanged(DataPreprocessingChangedEventType.ChangeItem, columnIndex, rowIndex);
    }

    public override void SetValues<T>(int columnIndex, IList<T> values) {
      SaveSnapshot(DataPreprocessingChangedEventType.ChangeColumn, columnIndex, -1);
      base.SetValues<T>(columnIndex, values);
      if (!IsInTransaction)
        OnChanged(DataPreprocessingChangedEventType.ChangeColumn, columnIndex, -1);
    }

    public override void InsertRow(int rowIndex) {
      SaveSnapshot(DataPreprocessingChangedEventType.DeleteRow, -1, rowIndex);
      base.InsertRow(rowIndex);
      if (!IsInTransaction)
        OnChanged(DataPreprocessingChangedEventType.AddRow, -1, rowIndex);
    }

    public override void DeleteRow(int rowIndex) {
      SaveSnapshot(DataPreprocessingChangedEventType.AddRow, -1, rowIndex);
      base.DeleteRow(rowIndex);
      if (!IsInTransaction)
        OnChanged(DataPreprocessingChangedEventType.DeleteRow, -1, rowIndex);
    }

    public override void InsertColumn<T>(string variableName, int columnIndex) {
      SaveSnapshot(DataPreprocessingChangedEventType.DeleteColumn, columnIndex, -1);
      base.InsertColumn<T>(variableName, columnIndex);
      if (!IsInTransaction)
        OnChanged(DataPreprocessingChangedEventType.AddColumn, columnIndex, -1);
    }

    public override void DeleteColumn(int columnIndex) {
      SaveSnapshot(DataPreprocessingChangedEventType.AddColumn, columnIndex, -1);
      base.DeleteColumn(columnIndex);
      if (!IsInTransaction)
        OnChanged(DataPreprocessingChangedEventType.DeleteColumn, columnIndex, -1);
    }

    #endregion

    #region TransactionalPreprocessingData members

    public event DataPreprocessingChangedEventHandler Changed;
    protected virtual void OnChanged(DataPreprocessingChangedEventType type, int column, int row) {
      var listeners = Changed;
      if (listeners != null) listeners(this, new DataPreprocessingChangedEventArgs(type, column, row));
    }

    public bool IsUndoAvailable {
      get { return undoHistory.Count > 0; }
    }

    public void Undo() {
      if (IsUndoAvailable) {
        Snapshot previousSnapshot = undoHistory[undoHistory.Count - 1];
        variableValues = previousSnapshot.VariableValues;
        variableNames = previousSnapshot.VariableNames;
        trainingToTestRatio = previousSnapshot.TrainingToTestRatio;
        transformations = previousSnapshot.Transformations;
        undoHistory.Remove(previousSnapshot);
        OnChanged(previousSnapshot.ChangedType,
          previousSnapshot.ChangedColumn,
          previousSnapshot.ChangedRow);
      }
    }

    public void InTransaction(Action action, DataPreprocessingChangedEventType type = DataPreprocessingChangedEventType.Any) {
      BeginTransaction(type);
      action();
      EndTransaction();
    }

    public void BeginTransaction(DataPreprocessingChangedEventType type) {
      SaveSnapshot(type, -1, -1);
      eventStack.Push(type);
    }

    public void EndTransaction() {
      if (eventStack.Count == 0)
        throw new InvalidOperationException("There is no open transaction that can be ended.");

      var @event = eventStack.Pop();
      OnChanged(@event, -1, -1);
    }

    #endregion
  }
}