using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using HeuristicLab.DataImporter.Data;
using HeuristicLab.DataImporter.Data.CommandBase;
using HeuristicLab.DataImporter.Data.Model;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.DataImporter.Command {
  [StorableClass]
  [ViewableCommandInfo("Fuzzy-link ColumnGroups", 2, ColumnGroupState.Sorted, "Time Series", Position = 4)]
  public class FuzzyLinkColumnGroupsCommand : DataSetCommandWithAffectedColumnGroupsBase {
    private ColumnGroup newColumnGroup;
    private ColumnGroup oldColumnGroup;
    private int removePos;

    private FuzzyLinkColumnGroupsCommand()
      : base(null, null) {
    }

    public FuzzyLinkColumnGroupsCommand(DataSet dataSet, List<string> affectedColumnGroups)
      : base(dataSet, affectedColumnGroups) {
    }

    //IMPORTANT this method has not been tested and therefore it is not guaranteed that it works as expected
    public override void Execute() {
      if (AffectedColumnGroupNames.Count != 2)
        throw new CommandExecutionException("This command only works if excatly two column groups are activated.", this);
      ColumnGroup leftColumnGroup = this.DataSet.GetColumnGroup(AffectedColumnGroupNames[0]);
      ColumnGroup rightColumnGroup = this.DataSet.GetColumnGroup(AffectedColumnGroupNames[1]);
      int leftIndex = this.DataSet.IndexOfColumnGroup(leftColumnGroup);
      int rightIndex = this.DataSet.IndexOfColumnGroup(rightColumnGroup);

      this.oldColumnGroup = rightColumnGroup;
      this.removePos = rightIndex;

      if (leftColumnGroup.SortedColumnsCount != 2 || rightColumnGroup.SortedColumnsCount != 2)
        throw new CommandExecutionException("Both ColumnGroups must be sorted by exactly two columns.", this);

      if (leftColumnGroup.SortOrdersForColumns.ElementAt(leftColumnGroup.SortedColumnIndexes.ElementAt(0)) !=
          rightColumnGroup.SortOrdersForColumns.ElementAt(rightColumnGroup.SortedColumnIndexes.ElementAt(0)) ||
          leftColumnGroup.SortOrdersForColumns.ElementAt(leftColumnGroup.SortedColumnIndexes.ElementAt(1)) !=
          rightColumnGroup.SortOrdersForColumns.ElementAt(rightColumnGroup.SortedColumnIndexes.ElementAt(1)) ||
          leftColumnGroup.SortOrdersForColumns.ElementAt(leftColumnGroup.SortedColumnIndexes.ElementAt(0)) != SortOrder.Ascending ||
          leftColumnGroup.SortOrdersForColumns.ElementAt(leftColumnGroup.SortedColumnIndexes.ElementAt(1)) != SortOrder.Ascending
        )
        throw new CommandExecutionException("Both ColumnGroups must be sorted in the same direction and ascending.", this);

      foreach (int sortColIndex in leftColumnGroup.SortedColumnIndexes) {
        if (leftColumnGroup.Columns.ElementAt(sortColIndex).ContainsNullValues)
          throw new CommandExecutionException("KeyColumns must not contain null values.", this);
      }
      foreach (int sortColIndex in rightColumnGroup.SortedColumnIndexes) {
        if (rightColumnGroup.Columns.ElementAt(sortColIndex).ContainsNullValues)
          throw new CommandExecutionException("KeyColumns must not contain null values.", this);
      }
      FuzzyLinkColumnGroups(leftColumnGroup, rightColumnGroup);

      DataSet.ReplaceColumnGroup(removePos, newColumnGroup);
      DataSet.FireChanged();
    }

    public override void UndoExecute() {
      DataSet.ReplaceColumnGroup(removePos, oldColumnGroup);
      DataSet.FireChanged();
    }


    public void FuzzyLinkColumnGroups(ColumnGroup left, ColumnGroup right) {
      ColumnBase keyColumn1 = left.Columns.ElementAt(left.SortedColumnIndexes.ElementAt(0));
      ColumnBase keyColumn2 = right.Columns.ElementAt(right.SortedColumnIndexes.ElementAt(0));
      ColumnBase fuzzyKeyColumn1 = left.Columns.ElementAt(left.SortedColumnIndexes.ElementAt(1));
      ColumnBase fuzzyKeyColumn2 = right.Columns.ElementAt(right.SortedColumnIndexes.ElementAt(1));

      this.newColumnGroup = new ColumnGroup(right.Name);
      foreach (ColumnBase col in right.Columns)
        newColumnGroup.AddColumn(col.CreateCopyOfColumnWithoutValues());

      // FOR NOW WE ASSERT THAT SORT ORDER IS ASCENDING
      //int keyCompareDirection = this.oldColumnGroup1.SortOrdersForColumns.ElementAt(oldColumnGroup1.SortedColumnIndices.ElementAt(0))
      //  == SortOrder.Ascending ? -1 : +1;
      //int fuzzyKeyCompareDirection = this.oldColumnGroup1.SortOrdersForColumns.ElementAt(oldColumnGroup1.SortedColumnIndices.ElementAt(1))
      //  == SortOrder.Ascending ? -1 : +1;

      IComparable[] row2;
      int[] firstMatchingColumn = new int[left.RowCount];
      int j = 0;
      // for all keys on left side fuzzy link to right side
      // first pass find indices of last rows on the right side with matching keys
      for (int i = 0; i < left.RowCount; i++) {
        // skip on the right side while the right side key is smaller than the left side key
        while (j < right.RowCount && keyColumn1.GetValue(i).CompareTo(keyColumn2.GetValue(j)) > 0) {
          j++;
        }
        // store the first j with the same key
        if (j < right.RowCount && keyColumn1.GetValue(i).CompareTo(keyColumn2.GetValue(j)) == 0) {
          firstMatchingColumn[i] = j;
        } else {
          firstMatchingColumn[i] = -1;
        }
      }
      // second pass to find the best fuzzy link (=same or next smaller value)
      j = firstMatchingColumn[0];
      for (int i = 0; i < left.RowCount; i++) {
        if (keyColumn1.GetValue(i).CompareTo(keyColumn2.GetValue(j)) != 0) j = firstMatchingColumn[i];
        if (j < 0) {
          // no matching key => add an empty row
          newColumnGroup.AddRow(right.GetEmptyRow());
        } else {
          int bestMatch = j;
          // go forward while the fuzzy key on the right is smaller than or equal to the fuzzy key on the left
          while (j < right.RowCount &&
            keyColumn1.GetValue(i).CompareTo(keyColumn2.GetValue(j)) == 0 &&
            fuzzyKeyColumn1.GetValue(i).CompareTo(fuzzyKeyColumn2.GetValue(j)) >= 0) {
            bestMatch = j;
            j++;
          }
          // invariant: j = right.RowCount OR best fuzzy-link = fuzzyKeyColumn2(bestMatch)
          // if we found a match take that row and otherwise use the empty row
          if (keyColumn1.GetValue(i).CompareTo(keyColumn2.GetValue(bestMatch)) == 0 &&
            fuzzyKeyColumn1.GetValue(i).CompareTo(fuzzyKeyColumn2.GetValue(bestMatch)) >= 0) {
            row2 = right.GetRow(bestMatch);
            j = bestMatch;
          } else {
            row2 = right.GetEmptyRow();
          }
          newColumnGroup.AddRow(row2);
        }
      }
    }

    public override string Description {
      get { return "Fuzzy-link column groups"; }
    }
  }
}