package casino

import (
	"math/rand"
	"strconv"
)

// card is a single playing card shared by every card-based table game.
type card struct {
	rank string
	suit string
}

func (c card) String() string { return c.rank + " of " + c.suit }

// blackjackValue scores aces as 11 and faces as 10.
func (c card) blackjackValue() int {
	switch c.rank {
	case "A":
		return 11
	case "K", "Q", "J":
		return 10
	default:
		value, _ := strconv.Atoi(c.rank)
		return value
	}
}

// baccaratValue scores aces as 1 and faces/tens as 0.
func (c card) baccaratValue() int {
	switch c.rank {
	case "K", "Q", "J", "10":
		return 0
	case "A":
		return 1
	default:
		value, _ := strconv.Atoi(c.rank)
		return value
	}
}

// shoe is a shuffled multi-deck card shoe shared by card table games. It
// reshuffles once the remaining cards fall to the shuffleAt fraction.
type shoe struct {
	cards     []card
	rng       *rand.Rand
	decks     int
	shuffleAt float64
}

func newShoe(decks int, shuffleAt float64, rng *rand.Rand) *shoe {
	s := &shoe{rng: rng, decks: decks, shuffleAt: shuffleAt}
	s.shuffle()
	return s
}

func (s *shoe) shuffle() {
	ranks := []string{"A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K"}
	suits := []string{"clubs", "diamonds", "hearts", "spades"}
	s.cards = make([]card, 0, s.decks*52)
	for deck := 0; deck < s.decks; deck++ {
		for _, suit := range suits {
			for _, rank := range ranks {
				s.cards = append(s.cards, card{rank: rank, suit: suit})
			}
		}
	}
	s.rng.Shuffle(len(s.cards), func(i, j int) { s.cards[i], s.cards[j] = s.cards[j], s.cards[i] })
}

func (s *shoe) draw() card {
	if s.shuffleAt > 0 && len(s.cards) <= int(float64(s.decks*52)*s.shuffleAt) {
		s.shuffle()
	}
	card := s.cards[len(s.cards)-1]
	s.cards = s.cards[:len(s.cards)-1]
	return card
}