pokercore/scoring.go

package pokercore

import (
	"fmt"
)

type HandScore int

const (
	ScoreHighCard = HandScore(iota * 100_000_000_000)
	ScorePair
	ScoreTwoPair
	ScoreThreeOfAKind
	ScoreStraight
	ScoreFlush
	ScoreFullHouse
	ScoreFourOfAKind
	ScoreStraightFlush
	ScoreRoyalFlush
)

func (c Card) Score() HandScore {
	return HandScore(c.Rank.Score())
}

func (c Cards) PokerHandScore() (HandScore, error) {
	ph, err := c.PokerHand()
	if err != nil {
		return 0, err
	}
	return ph.Score, nil
}

func (x HandScore) String() string {
	return fmt.Sprintf("<HandScore %d>", x)
}

func (ph *PokerHand) calculateScore() {

	// sanity check, we should only be called in the PokerHand() method from
	// a Cards, but just in case
	if len(ph.Hand) != 5 {
		// normally we don't panic in a library but this is a "should never
		// happen"
		panic("PokerHand.calculateScore() called on a PokerHand with != 5 cards")
	}

	if ph.Hand.containsRoyalFlush() {
		ph.Type = RoyalFlush
		ph.Score = ScoreRoyalFlush
		return
	}

	if ph.Hand.containsStraightFlush() {
		ph.Type = StraightFlush
		ph.Score = ScoreStraightFlush
		ph.Score += 1000 * ph.Hand.HighestRank().Score()
		return
	}

	if ph.Hand.containsFourOfAKind() {
		ph.Type = FourOfAKind
		ph.Score = ScoreFourOfAKind
		ph.Score += 1000 * ph.Hand.fourOfAKindRank().Score()
		ph.Score += 100 * ph.Hand.fourOfAKindKicker().Score()
		return
	}

	if ph.Hand.containsFullHouse() {
		ph.Type = FullHouse
		ph.Score = ScoreFullHouse
		// FIXME write a good test for this
		ph.Score += 1000 * ph.Hand.fullHouseTripsRank().Score()
		ph.Score += 100 * ph.Hand.fullHousePairRank().Score()
		return
	}

	if ph.Hand.containsFlush() {
		ph.Type = Flush
		ph.Score = ScoreFlush
		// flush base score plus sum of card ranks
		ph.Score += ph.Hand[0].Score()
		ph.Score += ph.Hand[1].Score()
		ph.Score += ph.Hand[2].Score()
		ph.Score += ph.Hand[3].Score()
		ph.Score += ph.Hand[4].Score()
		return
	}

	if ph.Hand.containsStraight() {
		ph.Type = Straight
		ph.Score = ScoreStraight

		// note that ph.Hand is already sorted by rank ascending with ace
		// high

		// Straights are scored by the highest card in the straight
		// UNLESS the second highest card is a 5 and the highest card is an Ace
		// In that case, the straight is a 5-high straight, not an Ace-high straight
		if ph.Hand[3].Rank == FIVE && ph.Hand[4].Rank == ACE {
			// 5-high straight, scored by the five's rank
			ph.Score += ph.Hand[3].Score()
		} else {
			// All other straights are scored by the highest card in the straight
			ph.Score += ph.Hand[4].Score()
		}
		return
	}

	if ph.Hand.containsThreeOfAKind() {
		ph.Type = ThreeOfAKind
		ph.Score = ScoreThreeOfAKind
		ph.Score += 1000 * ph.Hand.threeOfAKindTripsRank().Score()
		ph.Score += 100 * ph.Hand.threeOfAKindFirstKicker().Score()
		ph.Score += 10 * ph.Hand.threeOfAKindSecondKicker().Score()
		return
	}

	if ph.Hand.containsTwoPair() {
		ph.Type = TwoPair
		ph.Score = ScoreTwoPair
		ph.Score += 1000 * ph.Hand.twoPairBiggestPair().Score()
		ph.Score += 100 * ph.Hand.twoPairSmallestPair().Score()
		ph.Score += 10 * ph.Hand.twoPairKicker().Score()
		return
	}

	if ph.Hand.containsPair() {
		ph.Type = Pair
		ph.Score = ScorePair
		ph.Score += 1000 * ph.Hand.pairRank().Score()
		ph.Score += 100 * ph.Hand.pairFirstKicker().Score()
		ph.Score += 10 * ph.Hand.pairSecondKicker().Score()
		ph.Score += ph.Hand.pairThirdKicker().Score()
		return
	}

	ph.Type = HighCard
	ph.Score = ScoreHighCard // base score
	// unmade hands are scored like flushes, just add up the values
	ph.Score += ph.Hand[0].Score()
	ph.Score += ph.Hand[1].Score()
	ph.Score += ph.Hand[2].Score()
	ph.Score += ph.Hand[3].Score()
	ph.Score += ph.Hand[4].Score()
	return
}