using System;
using System.Collections.Generic;
using System.Linq;
using HeuristicLab.Core;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
using HeuristicLab.EvolutionTracking;

namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
  public class SymbolicDataAnalysisExpressionAfterCrossoverOperator : AfterCrossoverOperator<ISymbolicExpressionTree> {
    public override IOperation Apply() {
      var childVertex = GenealogyGraph[ChildParameter.ActualValue].Last();
      var arc0 = (IGenealogyGraphArc)childVertex.InArcs[0];
      var arc1 = (IGenealogyGraphArc)childVertex.InArcs[1];
      var nodes0 = (List<ISymbolicExpressionTreeNode>)arc0.Data;
      var nodes1 = (List<ISymbolicExpressionTreeNode>)arc1.Data;
      var childNodes = ChildParameter.ActualValue.IterateNodesBreadth().ToList();
      IFragment<ISymbolicExpressionTreeNode> fragment = null;

      for (int i = 0; i < Math.Min(nodes0.Count, childNodes.Count); ++i) {
        if (nodes0[i] == childNodes[i]) continue;
        fragment = new Fragment<ISymbolicExpressionTreeNode> {
          Root = childNodes[i],
          Index = i
        };
      }
      if (fragment == null) throw new Exception("Could not determine fragment!");

      for (int i = 0; i < nodes1.Count; ++i) {
        if (nodes1[i] != fragment.Root) continue;
        fragment.OldIndex = i;
      }

      arc0.Data = null;
      arc1.Data = fragment;

      return base.Apply();
    }
  }
}