namespace Yuuna.Contracts.Optimization
{
    using System.Collections.Generic;

    public sealed class ScoreComparer : IComparer<IScore>
    {
        public readonly static IComparer<IScore> Default = new ScoreComparer();

        private ScoreComparer()
        { 
        }

        public int Compare(IScore x, IScore y)
        {
            var f1 = x.Contrast.SequentialKeys.Count == x.SequentialMatches.Count;
            var f2 = y.Contrast.SequentialKeys.Count == y.SequentialMatches.Count;
            if (f1 & f2)
                return x.Contrast.SequentialKeys.Count - y.Contrast.SequentialKeys.Count;
            else if (f1)
                return 1;
            else if (f2)
                return -1;
            else
            {
                var v1 = x.Contrast.SequentialKeys.Count - x.SequentialMatches.Count;
                var v2 = y.Contrast.SequentialKeys.Count - y.SequentialMatches.Count;
                if (v1 > v2)
                    return -v2;
                else if (v1 < v2)
                    return v1;
                return x.Contrast.SequentialKeys.Count - y.Contrast.SequentialKeys.Count;
            }
        }
    }
}