path: root/internal/casino/roulette_racetrack.go

package casino

import (
	"fmt"
	"strconv"
	"strings"
)

// rouletteShare is a total-return fraction: a winning pocket pays
// stake*num/den credits, floor-rounded like a house paying in chips.
// Ordinary bets have den 1. Call bets split the stake across several chips,
// so their shares carry a denominator; a pocket covered by more than one
// component (for example 17 in Orphelins) sums those component returns into
// one share.
type rouletteShare struct {
	num int
	den int
}

// payout returns floor(stake*num/den) and refuses a wager whose return would
// exceed the economy's credit cap, without overflowing stake*num.
func (s rouletteShare) payout(stake int) (int, error) {
	if stake <= 0 || s.num <= 0 || s.den <= 0 {
		return 0, nil
	}
	if limit := ((MaxCredits+1)*s.den - 1) / s.num; stake > limit {
		return MaxCredits, fmt.Errorf("payout overflow: %d * %d/%d exceeds %d", stake, s.num, s.den, MaxCredits)
	}
	return stake * s.num / s.den, nil
}

// rouletteWager is a resolved wager: every covered pocket and its total-return
// share. A wager can cover one pocket (straight), many pockets at one rate
// (outside or inside combination), or several chip components at different
// rates (the racetrack call bets).
type rouletteWager struct {
	shares map[string]rouletteShare
}

func (w rouletteWager) covers(pocket string) (rouletteShare, bool) {
	share, ok := w.shares[pocket]
	return share, ok
}

// validate verifies that every possible winning pocket pays a representable
// amount for this stake before the wager is committed.
func (w rouletteWager) validate(stake int) error {
	for _, share := range w.shares {
		if _, err := share.payout(stake); err != nil {
			return err
		}
	}
	return nil
}

// rouletteComponent is one chip group inside a call bet: the pockets it covers
// and the total-return multiplier (stake included) paid when one of them hits.
type rouletteComponent struct {
	pockets []string
	chips   int
	mult    int
}

// rouletteCallBet is a fixed French/racetrack bet. The series is the display
// order (wheel order) and parts are the actual chip placement.
type rouletteCallBet struct {
	canonical string
	name      string
	chips     int
	series    []string
	parts     []rouletteComponent
}

// RacetrackBetView is one call bet for the presentation layer.
type RacetrackBetView struct {
	Name   string
	Syntax string
	Chips  int
	Series []string
}

// RacetrackBets returns the fixed French call bets in display order. The
// numbers are shown for reference; the actual wagers are the named bets.
func RacetrackBets() []RacetrackBetView {
	views := make([]RacetrackBetView, 0, len(rouletteCallBets))
	for _, bet := range rouletteCallBets {
		views = append(views, RacetrackBetView{
			Name:   bet.name,
			Syntax: bet.canonical,
			Chips:  bet.chips,
			Series: append([]string(nil), bet.series...),
		})
	}
	return views
}

// The four standard single-zero call bets. Chip placements and payouts follow
// the traditional layout: Voisins (9 chips), Tiers (6), Orphelins (5) and
// Jeu Zero (4). Every inside component returns 36/covered, so the combined
// wager keeps the wheel's normal house edge before whole-credit rounding.
var rouletteCallBets = []rouletteCallBet{
	{
		canonical: "voisins",
		name:      "Voisins du Zero",
		chips:     9,
		series:    []string{"22", "18", "29", "7", "28", "12", "35", "3", "26", "0", "32", "15", "19", "4", "21", "2", "25"},
		parts: []rouletteComponent{
			{pockets: []string{"0", "2", "3"}, chips: 2, mult: 12}, // trio
			{pockets: []string{"4", "7"}, chips: 1, mult: 18},
			{pockets: []string{"12", "15"}, chips: 1, mult: 18},
			{pockets: []string{"18", "21"}, chips: 1, mult: 18},
			{pockets: []string{"19", "22"}, chips: 1, mult: 18},
			{pockets: []string{"25", "26", "28", "29"}, chips: 2, mult: 9}, // corner
			{pockets: []string{"32", "35"}, chips: 1, mult: 18},
		},
	},
	{
		canonical: "tiers",
		name:      "Tiers du Cylindre",
		chips:     6,
		series:    []string{"27", "13", "36", "11", "30", "8", "23", "10", "5", "24", "16", "33"},
		parts: []rouletteComponent{
			{pockets: []string{"5", "8"}, chips: 1, mult: 18},
			{pockets: []string{"10", "11"}, chips: 1, mult: 18},
			{pockets: []string{"13", "16"}, chips: 1, mult: 18},
			{pockets: []string{"23", "24"}, chips: 1, mult: 18},
			{pockets: []string{"27", "30"}, chips: 1, mult: 18},
			{pockets: []string{"33", "36"}, chips: 1, mult: 18},
		},
	},
	{
		canonical: "orphelins",
		name:      "Orphelins",
		chips:     5,
		series:    []string{"17", "34", "6", "1", "20", "14", "31", "9"},
		parts: []rouletteComponent{
			{pockets: []string{"1"}, chips: 1, mult: 36},
			{pockets: []string{"6", "9"}, chips: 1, mult: 18},
			{pockets: []string{"14", "17"}, chips: 1, mult: 18},
			{pockets: []string{"17", "20"}, chips: 1, mult: 18},
			{pockets: []string{"31", "34"}, chips: 1, mult: 18},
		},
	},
	{
		canonical: "jeuzero",
		name:      "Jeu Zero",
		chips:     4,
		series:    []string{"12", "35", "3", "26", "0", "32", "15"},
		parts: []rouletteComponent{
			{pockets: []string{"0", "3"}, chips: 1, mult: 18},
			{pockets: []string{"12", "15"}, chips: 1, mult: 18},
			{pockets: []string{"32", "35"}, chips: 1, mult: 18},
			{pockets: []string{"26"}, chips: 1, mult: 36},
		},
	},
}

// rouletteCallAliases maps the many spellings players use onto a canonical
// call bet. Accents are stripped before lookup.
var rouletteCallAliases = map[string]string{
	"voisins":                "voisins",
	"voisins du zero":        "voisins",
	"grands voisins":         "voisins",
	"grands voisins du zero": "voisins",
	"vdz":                    "voisins",
	"tiers":                  "tiers",
	"tiers du cylindre":      "tiers",
	"le tiers du cylindre":   "tiers",
	"tdc":                    "tiers",
	"small series":           "tiers",
	"orphelins":              "orphelins",
	"orphans":                "orphelins",
	"les orphelins":          "orphelins",
	"zero":                   "jeuzero",
	"jeu zero":               "jeuzero",
	"jeuzero":                "jeuzero",
}

// neighborsRadius is how many pockets on each side of the chosen number the
// neighbours bet includes: the number plus four either side, nine in total.
const neighborsRadius = 4

// wager converts a call bet's chip placement into per-pocket return shares,
// summing shares where components overlap (17 in Orphelins).
func (b rouletteCallBet) wager() rouletteWager {
	shares := map[string]rouletteShare{}
	for _, part := range b.parts {
		for _, pocket := range part.pockets {
			share := shares[pocket]
			shares[pocket] = rouletteShare{num: share.num + part.chips*part.mult, den: b.chips}
		}
	}
	return rouletteWager{shares: shares}
}

// normalizeRacetrackName lowercases, strips accents and collapses whitespace so
// "Voisins du Zéro" and "voisins  du zero" resolve the same way.
func normalizeRacetrackName(spot string) string {
	name := strings.ToLower(strings.TrimSpace(spot))
	name = strings.NewReplacer("é", "e", "è", "e", "ê", "e", "à", "a", "ô", "o", "û", "u").Replace(name)
	return strings.Join(strings.Fields(name), " ")
}

// rouletteRacetrackWager resolves a call bet or a neighbours bet for a
// single-zero table whose racetrack is enabled.
func rouletteRacetrackWager(spot string, double bool) (rouletteWager, bool) {
	if double {
		return rouletteWager{}, false
	}
	if canonical, ok := rouletteCallAliases[normalizeRacetrackName(spot)]; ok {
		for _, bet := range rouletteCallBets {
			if bet.canonical == canonical {
				return bet.wager(), true
			}
		}
	}
	return rouletteNeighborsWager(spot, double)
}

// rouletteNeighborsWager covers the chosen pocket and the four pockets on each
// side of it in wheel order, one chip each (nine chips, a uniform 3:1 return).
// It accepts "neighbors 17", "neighbors of 17", "17 neighbors" and the British
// "neighbours" spelling.
func rouletteNeighborsWager(spot string, double bool) (rouletteWager, bool) {
	if double {
		return rouletteWager{}, false
	}
	keyword := false
	number := ""
	numbers := 0
	for _, field := range strings.Fields(strings.ToLower(spot)) {
		switch field {
		case "neighbor", "neighbors", "neighbour", "neighbours":
			keyword = true
			continue
		case "of", "the", "around":
			continue
		}
		pocket, ok := roulettePocketToken(field, double)
		if !ok {
			return rouletteWager{}, false
		}
		number = pocket
		numbers++
	}
	if !keyword || numbers != 1 || number == "" {
		return rouletteWager{}, false
	}
	wheel := rouletteWheel(false)
	index := -1
	for i, pocket := range wheel {
		if pocket == number {
			index = i
			break
		}
	}
	if index < 0 {
		return rouletteWager{}, false
	}
	shares := map[string]rouletteShare{}
	for d := -neighborsRadius; d <= neighborsRadius; d++ {
		pocket := wheel[(index+d+len(wheel))%len(wheel)]
		shares[pocket] = rouletteShare{num: 36, den: 2*neighborsRadius + 1}
	}
	return rouletteWager{shares: shares}, true
}

// rouletteWagerFor resolves any roulette target into a wager. Call bets and
// neighbours are reachable only on a single-zero table with the racetrack
// enabled; every other target uses the ordinary uniform bets.
func rouletteWagerFor(spot string, double, racetrack bool) (rouletteWager, bool) {
	if racetrack && !double {
		if wager, ok := rouletteRacetrackWager(spot, double); ok {
			return wager, true
		}
	}
	pockets, mult := rouletteBet(spot, double)
	if mult == 0 {
		return rouletteWager{}, false
	}
	shares := make(map[string]rouletteShare, len(pockets))
	for _, pocket := range pockets {
		shares[pocket] = rouletteShare{num: mult, den: 1}
	}
	return rouletteWager{shares: shares}, true
}

// formatShare renders a share for diagnostics and tests without floating
// point.
func formatShare(share rouletteShare) string {
	if share.den == 1 {
		return strconv.Itoa(share.num)
	}
	return fmt.Sprintf("%d/%d", share.num, share.den)
}