using System.Linq;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Encodings.BinaryVectorEncoding;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Problems.NK {

  [Item("Median Bit Binary Vector Comparer", "Compares two binary vectors by the median positive bit location")]
  [StorableClass]
  public sealed class MedianBitBinaryVectorComparer : BinaryVectorComparer {

    [StorableConstructor]
    private MedianBitBinaryVectorComparer(bool deserializing) : base(deserializing) { }
    private MedianBitBinaryVectorComparer(MedianBitBinaryVectorComparer original, Cloner cloner)
      : base(original, cloner) {
    }
    public MedianBitBinaryVectorComparer() { }
    public override IDeepCloneable Clone(Cloner cloner) {
      return new MedianBitBinaryVectorComparer(this, cloner);
    }

    public static int MedianBit(BinaryVector x) {
      var activeIndices = x.Select((b, i) => new { b, i }).Where(v => v.b).ToList();
      if (activeIndices.Count > 0)
        return activeIndices[activeIndices.Count / 2].i;
      else
        return 0;
    }
    public override int Compare(BinaryVector x, BinaryVector y) {
      return MedianBit(x) - MedianBit(y);
    }
  }
}