card-counting.cs

public HandRank GetHandRank() =>
    IsRoyalFlush() ? HandRank.RoyalFlush :
    IsStraightFlush() ? HandRank.StraightFlush :
    IsFourOfAKind() ? HandRank.FourOfAKind :
    IsFullHouse() ? HandRank.FullHouse :
    IsFlush() ? HandRank.Flush :
    IsStraight() ? HandRank.Straight :
    IsThreeOfAKind() ? HandRank.ThreeOfAKind :
    IsTwoPair() ? HandRank.TwoPair :
    IsPair() ? HandRank.Pair :
    HandRank.HighCard;

private bool IsRoyalFlush() => IsFlush() && Cards.All(x => x.Value >= CardValue.Ten);

private bool IsStraightFlush() => IsStraight() && IsFlush();

private bool IsFourOfAKind() =>
    Cards.GroupBy(x => x.Value).Any(x => x.Count() == 4);

private bool IsFullHouse() =>
    Cards.GroupBy(x => x.Value).Any(x => x.Count() == 3) &&
        Cards.GroupBy(x => x.Value).Any(x => x.Count() == 2);

private bool IsFlush() => Cards.All(x => x.Suit == Cards.First().Suit);

private bool IsStraight() =>
    Cards.GroupBy(x => x.Value).Count() == 5 &&
        Cards.Max(x => x.Value) - Cards.Min(x => x.Value) == 4;

private bool IsThreeOfAKind() => Cards.GroupBy(x => x.Value).Any(x => x.Count() == 3);

private bool IsTwoPair() => Cards.GroupBy(x => x.Value).Select(grp => new { grp.Key, Count = grp.Count() })
    .GroupBy(x => x.Count).Any(x => x.Count() == 2);

private bool IsPair() => Cards.GroupBy(x => x.Value).Any(x => x.Count() == 2);