path: root/internal/casino/baccarat.go

package casino

import (
	"fmt"
	"math/rand"
)

// Baccarat uses the shared table phases; these aliases keep the call sites
// readable.
const (
	baccaratWaiting = phaseWaiting
	baccaratBetting = phaseBetting
)

// baccaratSpots are the outcomes a participant may wager on.
const (
	baccaratSpotPlayer = "player"
	baccaratSpotBanker = "banker"
	baccaratSpotTie    = "tie"
)

type baccaratPlayer struct {
	Participant
	// mainSpot is the spot of the committed main wager (player, banker or
	// tie). Once the round ends it is what a bare "bet" repeats.
	mainSpot string
	// sides holds this round's optional side-bet stakes by spot.
	sides map[string]Wager
	// lastBets remembers the last stake placed on each spot so a bare "bet"
	// can repeat the side bets and the main wager together.
	lastBets map[string]int
}

func (p *baccaratPlayer) participantPtr() *Participant { return &p.Participant }

// totalStaked is every credit this seat has committed to the current round.
func (p *baccaratPlayer) totalStaked() int {
	total := 0
	if p.HasBet {
		total += p.Wager.Total
	}
	for _, w := range p.sides {
		total += w.Total
	}
	return total
}

// sideSpots lists committed side spots in the table's own order so menus and
// settlements never depend on map iteration.
func (p *baccaratPlayer) sideSpots(rules BaccaratConfig) []string {
	var spots []string
	for _, spot := range rules.spots() {
		if baccaratIsMainSpot(spot) || p.sides[spot].Total == 0 {
			continue
		}
		spots = append(spots, spot)
	}
	return spots
}

// wagers lists the main wager first, then every side bet, as one settlement
// and snapshot unit each.
func (p *baccaratPlayer) wagers(rules BaccaratConfig) []baccaratWager {
	var out []baccaratWager
	if p.HasBet {
		out = append(out, baccaratWager{spot: p.mainSpot, wager: p.Wager})
	}
	for _, spot := range p.sideSpots(rules) {
		out = append(out, baccaratWager{spot: spot, wager: p.sides[spot]})
	}
	return out
}

func (p *baccaratPlayer) hasLastBet() bool {
	for _, amount := range p.lastBets {
		if amount > 0 {
			return true
		}
	}
	return false
}

// baccaratWager pairs a committed stake with the spot it rides on.
type baccaratWager struct {
	spot  string
	wager Wager
}

func baccaratIsMainSpot(spot string) bool {
	return spot == baccaratSpotPlayer || spot == baccaratSpotBanker || spot == baccaratSpotTie
}

type baccaratTable struct {
	tableCore[*baccaratPlayer]
	Rules BaccaratConfig
	shoe  *shoe
}

func newBaccaratTable(roomID int, cfg TableConfig, rng *rand.Rand) *baccaratTable {
	cfg = cfg.Normalize()
	rules := cfg.Baccarat.Normalize()
	return &baccaratTable{
		tableCore: newTableCore[*baccaratPlayer](&tableBase{RoomID: roomID, Config: cfg}),
		Rules:     rules,
		shoe:      newShoe(rules.Decks, rules.ShuffleAt, rng),
	}
}

func (t *baccaratTable) menuEvent(name string) Event {
	p := t.players.get(name)
	if p != nil && p.HasBet {
		return t.committedMenu(name)
	}
	commands := []MenuCommand{}
	if p != nil && p.hasLastBet() {
		commands = append(commands, MenuCommand{Command: "bet", Desc: "Repeat your last bets"})
	}
	if p != nil && len(p.sides) > 0 {
		commands = append(commands, MenuCommand{Command: "unbet", Desc: "Take back your side bets"})
	}
	commands = append(commands,
		MenuCommand{Command: fmt.Sprintf("bet %d banker", t.Config.MinBet)},
		MenuCommand{Command: "bet <amount> on <bet>"},
		MenuCommand{Command: "stop", Desc: "Leave; during a round, leave afterward"},
		MenuCommand{Command: "table", Desc: "Check the table"})
	commands = withTableHints(commands, t.wagerRows())
	e := t.betMenuEvent(name, commands)
	if p != nil {
		e.Menu.Repeat = p.hasLastBet()
	}
	return e
}

func (t *baccaratTable) join(name string) []Event {
	t.mu.Lock()
	defer t.mu.Unlock()
	if t.players.has(name) {
		return []Event{t.menuEvent(name)}
	}
	if t.players.count() >= t.Config.MaxPlayers {
		return []Event{t.private(name, "That baccarat table is full.")}
	}
	events := []Event{t.addSeatLocked(name, &baccaratPlayer{Participant: Participant{Name: name, Connected: true}})}
	// The rules board is a rendered felt (presentation layer); the engine
	// only ships the configuration.
	rules := t.private(name, "")
	rules.Snapshot = &BaccaratRulesView{Config: t.Config}
	events = append(events, rules, t.menuEvent(name))
	return events
}

func (t *baccaratTable) leave(name string) []Event {
	t.mu.Lock()
	defer t.mu.Unlock()
	p := t.players.get(name)
	if p == nil {
		return nil
	}
	// A wager is committed for the round in flight; everyone else may stand
	// up whenever they like.
	if p.totalStaked() > 0 {
		return []Event{t.private(name, "You're in the middle of a baccarat round!")}
	}
	var events []Event
	events = append(events, t.refundSidesLocked(p)...)
	t.removeSeatLocked(name)
	events = append(events, t.playerAction(name, fmt.Sprintf("%s stands up.", name), "You stand up."))
	return t.closeIfEmptyLocked(events)
}

// bet commits one wager: a main bet (player, banker or tie) or a side bet.
// Side bets may only be placed before the main wager, so the main bet remains
// the single trigger that ends the betting window and deals the cards.
func (t *baccaratTable) bet(name, spot string, amount int, wallet Wallet) []Event {
	t.mu.Lock()
	defer t.mu.Unlock()
	p := t.players.get(name)
	if p == nil {
		return []Event{t.private(name, "You aren't playing baccarat.")}
	}
	if spot == "" {
		spot = p.mainSpot
	}
	if spot == "" {
		return []Event{t.private(name, "Bet on what? Try bet <amount> on "+t.Rules.betChoices()+".")}
	}
	if !t.Rules.allowsSpot(spot) {
		return []Event{t.private(name, "Baccarat bets must be on player, banker, or tie, or an enabled optional bet. Available: "+t.Rules.betChoices()+".")}
	}
	events, ok := t.placeBetLocked(p, spot, amount, wallet)
	if !ok {
		return events
	}
	return t.finishBetLocked(events)
}

// placeBetLocked validates and commits a single wager without deciding
// whether the round should start. It reports false with a refusal event when
// the wager is not allowed.
func (t *baccaratTable) placeBetLocked(p *baccaratPlayer, spot string, amount int, wallet Wallet) ([]Event, bool) {
	isMain := baccaratIsMainSpot(spot)
	if isMain && p.HasBet {
		return []Event{t.private(p.Name, "You have already bet a main wager this round.")}, false
	}
	if !isMain {
		if p.sides[spot].Total > 0 {
			return []Event{t.private(p.Name, "You have already bet that side wager this round.")}, false
		}
		if p.HasBet {
			return []Event{t.private(p.Name, "Place side bets before your main wager.")}, false
		}
	}
	if amount < t.Config.MinBet || amount > t.Config.MaxBet {
		return []Event{t.private(p.Name, fmt.Sprintf("Baccarat bets must be %s.", betRangeText(t.Config.MinBet, t.Config.MaxBet)))}, false
	}
	if wallet == nil {
		return []Event{t.private(p.Name, "Wallet unavailable.")}, false
	}
	stake, err := wallet.Wager(amount)
	if err != nil {
		return []Event{t.private(p.Name, walletErrorMessage(err))}, false
	}
	p.Wallet = wallet
	p.SittingOut = false
	if p.lastBets == nil {
		p.lastBets = map[string]int{}
	}
	p.lastBets[spot] = amount
	if isMain {
		p.HasBet, p.Wager, p.mainSpot = true, stake, spot
	} else {
		if p.sides == nil {
			p.sides = map[string]Wager{}
		}
		p.sides[spot] = stake
	}
	return []Event{t.playerAction(p.Name,
		fmt.Sprintf("%s bets %d credits on %s.", p.Name, amount, spot),
		fmt.Sprintf("You bet %d credits on %s.", amount, spot))}, true
}

// finishBetLocked opens the shared betting window and deals the moment every
// active seat has a main wager. Side bets on their own never deal.
func (t *baccaratTable) finishBetLocked(events []Event) []Event {
	events = t.openBettingLocked(events)
	if allBet(t.players.participants()) {
		events = append(events, t.deal()...)
	}
	return events
}

// rebetAll repeats every remembered side bet and then the main wager in one
// command. It is the baccarat meaning of a bare "bet".
func (t *baccaratTable) rebetAll(name string, wallet Wallet) []Event {
	t.mu.Lock()
	defer t.mu.Unlock()
	p := t.players.get(name)
	if p == nil {
		return []Event{t.private(name, "You aren't playing baccarat.")}
	}
	if p.HasBet {
		return []Event{t.private(name, "You have already bet a main wager this round.")}
	}
	if !p.hasLastBet() {
		return []Event{t.private(name, "Bet on what? Try bet <amount> on "+t.Rules.betChoices()+".")}
	}
	var events []Event
	for _, spot := range t.Rules.spots() {
		if baccaratIsMainSpot(spot) {
			continue
		}
		if amount := p.lastBets[spot]; amount > 0 {
			ev, ok := t.placeBetLocked(p, spot, amount, wallet)
			events = append(events, ev...)
			if !ok {
				return events
			}
		}
	}
	if p.mainSpot != "" {
		if amount := p.lastBets[p.mainSpot]; amount > 0 {
			ev, ok := t.placeBetLocked(p, p.mainSpot, amount, wallet)
			events = append(events, ev...)
			if !ok {
				return events
			}
		}
	}
	return t.finishBetLocked(events)
}

func (t *baccaratTable) tick() []Event {
	t.mu.Lock()
	defer t.mu.Unlock()
	if t.phase != baccaratBetting {
		return nil
	}
	sitOuts, goRound, pending := t.window.advance(t.players.participants())
	if pending {
		if !t.window.timer.warn() {
			return nil
		}
		var warnings []Event
		for _, p := range t.players.participants() {
			if p.Connected && !p.HasBet && !p.SittingOut {
				warnings = append(warnings, t.warning(p.Name, fmt.Sprintf("Betting closes in %d ticks. Bet now or sit out this hand.", t.window.timer.remaining())))
			}
		}
		return warnings
	}
	var events []Event
	// A seat with side bets but no main wager is not in the round; return the
	// side stakes rather than letting them ride on a hand their owner skipped.
	for _, p := range t.players.ordered() {
		if !p.HasBet && len(p.sides) > 0 {
			events = append(events, t.refundSidesLocked(p)...)
		}
	}
	for _, name := range sitOuts {
		events = append(events, t.event(fmt.Sprintf("%s sits out this baccarat round.", name), true))
	}
	if goRound {
		return append(events, t.deal()...)
	}
	t.resetRound()
	return events
}

func (t *baccaratTable) action(name, action string) []Event {
	t.mu.Lock()
	defer t.mu.Unlock()
	if action == "unbet" {
		return t.unbetAllLocked(name)
	}
	if events, handled := t.controlLocked(name, action); handled {
		// A seat that sits out or leaves before committing a main wager is not
		// in the round; return any side stakes it already placed.
		if p := t.players.get(name); p != nil && !p.HasBet && len(p.sides) > 0 {
			events = append(events, t.refundSidesLocked(p)...)
		}
		if t.phase == baccaratBetting && allBet(t.players.participants()) {
			return append(events, t.deal()...)
		}
		return events
	}
	return []Event{t.private(name, "That game has no player actions.")}
}

// unbetAllLocked returns every stake the seat has committed this round, main
// wager and side bets alike.
func (t *baccaratTable) unbetAllLocked(name string) []Event {
	p := t.players.get(name)
	if p == nil {
		return []Event{t.private(name, "You aren't seated at this table.")}
	}
	if t.phase != baccaratWaiting && t.phase != baccaratBetting {
		return []Event{t.private(name, "You can only take back bets before the round starts.")}
	}
	total := 0
	var ids []string
	if p.HasBet {
		total += p.Wager.Total
		if p.Wager.ID != "" {
			ids = append(ids, p.Wager.ID)
		}
	}
	for _, w := range p.sides {
		total += w.Total
		if w.ID != "" {
			ids = append(ids, w.ID)
		}
	}
	if total == 0 {
		return []Event{t.private(name, "Nothing to take back.")}
	}
	if p.Wallet != nil {
		if err := p.Wallet.PayCredits(total, ids...); err != nil {
			return []Event{t.private(name, payoutFailedMessage())}
		}
	}
	p.HasBet, p.Wager = false, Wager{}
	p.sides = nil
	return []Event{t.private(name, fmt.Sprintf("You take back %d credits.", total))}
}

// refundSidesLocked returns every side stake on a seat that never committed a
// main wager.
func (t *baccaratTable) refundSidesLocked(p *baccaratPlayer) []Event {
	total := 0
	var ids []string
	for _, spot := range p.sideSpots(t.Rules) {
		w := p.sides[spot]
		total += w.Total
		if w.ID != "" {
			ids = append(ids, w.ID)
		}
	}
	if total == 0 {
		return nil
	}
	if p.Wallet != nil {
		if err := p.Wallet.PayCredits(total, ids...); err != nil {
			return []Event{t.private(p.Name, "Your side bets could not be returned just now; the stake stays pending and will be refunded after the next server restart.")}
		}
	}
	p.sides = nil
	return []Event{t.private(p.Name, fmt.Sprintf("Your %d in side bets is returned; no main wager was placed.", total))}
}

func (t *baccaratTable) rebet(name string) (string, int) {
	t.mu.Lock()
	defer t.mu.Unlock()
	p := t.players.get(name)
	if p == nil {
		return "", t.Config.MinBet
	}
	if p.mainSpot != "" && p.lastBets[p.mainSpot] > 0 {
		return p.mainSpot, p.lastBets[p.mainSpot]
	}
	return "", t.Config.MinBet
}

// deal plays out the hand by the punto banco tableau, settles every wager,
// and resets the table for the next round.
func (t *baccaratTable) deal() []Event {
	// The cut-card reshuffle and the round-coverage guarantee both happen at
	// this boundary, before a single card of the coup is dealt (deal() is
	// synchronous, so a wager here has never had a card dealt for it):
	// draw() rebuilds an exhausted shoe in place, which mid-coup could deal
	// a card the coup already holds.
	t.shoe.shuffleIfDue()
	t.shoe.ensureForRound(baccaratRoundCards)
	player, banker := playTableau(t.shoe)
	playerTotal, bankerTotal := baccaratTotal(player), baccaratTotal(banker)
	round := t.event("New baccarat hand!", true)
	round.Snapshot = t.snapshot(player, banker)
	events := []Event{round, t.event(baccaratOutcomeMessage(playerTotal, bankerTotal), true)}
	if explanation := baccaratVariantOutcome(player, banker, t.Rules); explanation != "" {
		events = append(events, t.event(explanation, true))
	}
	for _, p := range t.players.ordered() {
		if !p.HasBet {
			continue
		}
		wagers := p.wagers(t.Rules)
		lines := make([]settlementLine, 0, len(wagers))
		var ids []string
		totalStake, totalReturn := 0, 0
		var payoutErr error
		for _, w := range wagers {
			result, payout, err := settleBaccaratHand(w.spot, w.wager.Total, player, banker, t.Rules)
			if err != nil && payoutErr == nil {
				payoutErr = err
			}
			if w.wager.ID != "" {
				ids = append(ids, w.wager.ID)
			}
			totalStake += w.wager.Total
			totalReturn += payout
			line := settlementLine{Label: w.spot, Odds: baccaratSettlementOdds(w.spot, player, banker, t.Rules), Result: result, Stake: w.wager.Total, Returned: payout}
			if result == "win" && w.spot == baccaratSpotTie {
				line.Tag = "casino_jackpot_win"
			}
			lines = append(lines, line)
		}
		// The shared settlement path pays before announcing and leaves the
		// stakes pending on any failure, so a refund can never be paid on top
		// of a payout that was not durable.
		payoutFailed := settleStakeOutcome(p.Wallet, totalReturn, ids, payoutErr)
		publicResult, _ := baccaratResultMessages(p.Name, returnResult(totalStake, totalReturn), totalReturn)
		privateResult := settlementText(lines)
		if payoutFailed {
			privateResult = payoutFailedMessage()
			publicResult = p.Name + "’s settlement is pending recovery."
		}
		settlement := t.playerAction(p.Name, publicResult, privateResult)
		// Returning players get their balance in the next bet menu; only
		// departures/sit-outs need it attached to the settlement.
		settlement.ShowBalance = !payoutFailed && (p.LeaveAfter || p.SitOutAfter || !p.Connected)
		if !payoutFailed {
			settlement.Settlement = lines
			switch {
			case len(lines) == 1 && lines[0].Tag != "":
				settlement.Color = lines[0].Tag
			case totalReturn > totalStake:
				settlement.Color = "casino_result_win"
			case totalReturn == totalStake:
				settlement.Color = "casino_result_push"
			default:
				settlement.Color = "casino_result_loss"
			}
		}
		events = append(events, settlement)
		// settleStakeOutcome already consumed these stakes by handle (a payout
		// removed them, a push/loss resolved them). Deliberately do NOT call the
		// player-wide ResolveStakes here: it would also consume a stake left
		// pending by an earlier failed payout, which must stay refundable.
	}
	t.resetRound()
	events = append(events, t.finishControlsLocked()...)
	for _, p := range t.players.ordered() {
		if p.Connected && !p.SittingOut {
			events = append(events, t.menuEvent(p.Name))
		}
	}
	return events
}

func (t *baccaratTable) snapshot(player, banker []card) *BaccaratSnapshot {
	snapshot := &BaccaratSnapshot{
		PlayerScore: fmt.Sprintf("%d", baccaratTotal(player)),
		BankerScore: fmt.Sprintf("%d", baccaratTotal(banker)),
	}
	for _, c := range player {
		snapshot.Player = append(snapshot.Player, CardView{Rank: c.rank, Suit: c.suit})
	}
	for _, c := range banker {
		snapshot.Banker = append(snapshot.Banker, CardView{Rank: c.rank, Suit: c.suit})
	}
	for _, p := range t.players.ordered() {
		for _, w := range p.wagers(t.Rules) {
			snapshot.Bets = append(snapshot.Bets, BaccaratBetView{Name: p.Name, Spot: w.spot, Amount: w.wager.Total})
		}
	}
	return snapshot
}

func (t *baccaratTable) resetRound() {
	t.phase = baccaratWaiting
	t.window.close()
	clearBets(t.players.participants())
	for _, p := range t.players.ordered() {
		p.sides = nil
	}
}

// markDisconnected removes the player from the table. A committed wager is
// REFUNDED rather than forfeited: deal() is synchronous, so a seated bettor
// whose wager is still outstanding has had no card dealt for it (the coup
// only starts once every connected seat has bet) and nothing is revealed by
// returning the stake. An open betting window then resolves or resets on the
// next tick now that they no longer hold it open.
func (t *baccaratTable) markDisconnected(name string) []Event {
	t.mu.Lock()
	defer t.mu.Unlock()
	if !t.players.has(name) {
		return nil
	}
	if p := t.players.get(name); p != nil && p.totalStaked() > 0 && p.Wallet != nil {
		if _, _, err := p.Wallet.RefundOutstanding(); err != nil {
			// The stake stays pending on disk and startup recovery will return
			// it, but tell the departing player instead of silently swallowing
			// the failure.
			t.removeSeatLocked(name)
			events := []Event{t.event(fmt.Sprintf("%s stands up.", name), true)}
			events = append(events, t.private(name, "Your stake could not be returned just now; it stays pending and will be refunded after the next server restart."))
			return t.closeIfEmptyLocked(events)
		}
	}
	t.removeSeatLocked(name)
	events := []Event{t.event(fmt.Sprintf("%s stands up.", name), true)}
	return t.closeIfEmptyLocked(events)
}

// baccaratTotal scores a hand modulo 10.
func baccaratTotal(hand []card) int {
	total := 0
	for _, c := range hand {
		total += c.baccaratValue()
	}
	return total % 10
}

// playTableau deals the initial four cards and applies the punto banco
// drawing rules, returning the final player and banker hands.
func playTableau(sh *shoe) (player, banker []card) {
	player = []card{sh.draw(), sh.draw()}
	banker = []card{sh.draw(), sh.draw()}
	playerTotal, bankerTotal := baccaratTotal(player), baccaratTotal(banker)
	if playerTotal >= 8 || bankerTotal >= 8 {
		// A natural 8 or 9 ends the hand immediately.
		return player, banker
	}
	playerThird := -1
	if playerTotal <= 5 {
		c := sh.draw()
		playerThird = c.baccaratValue()
		player = append(player, c)
	}
	if playerThird < 0 {
		if bankerTotal <= 5 {
			banker = append(banker, sh.draw())
		}
		return player, banker
	}
	if bankerDraws(bankerTotal, playerThird) {
		banker = append(banker, sh.draw())
	}
	return player, banker
}

// bankerDraws applies the banker tableau when the player took a third card.
func bankerDraws(bankerTotal, playerThird int) bool {
	switch bankerTotal {
	case 0, 1, 2:
		return true
	case 3:
		return playerThird != 8
	case 4:
		return playerThird >= 2 && playerThird <= 7
	case 5:
		return playerThird >= 4 && playerThird <= 7
	case 6:
		return playerThird == 6 || playerThird == 7
	default: // 7
		return false
	}
}

// settleBaccaratBet is the ordinary main-wager payout helper. Gameplay must
// use settleBaccaratHand first to apply variant exceptions and optional bets;
// totals alone cannot identify a three-card Banker seven.
// It returns the result label and total payout (stake plus winnings).
// Player and banker bets push on a tie. Winnings
// round down to whole credits, so the banker commission effectively rounds
// up: never bet less than one commission unit.
func settleBaccaratBet(spot string, bet int, playerTotal, bankerTotal int, rules BaccaratConfig) (string, int, error) {
	switch {
	case playerTotal > bankerTotal:
		if spot == baccaratSpotPlayer {
			return "win", bet * 2, nil
		}
	case bankerTotal > playerTotal:
		if spot == baccaratSpotBanker {
			bankerWin, err := MulPayout(bet, rules.BankerPayout)
			if err != nil {
				return "win", bet + bankerWin, err
			}
			// The banker commission rounds UP, not down: when the wager is
			// too small for a whole credit of commission, a winning banker
			// bet returns only the stake. MulPayout's positive-stake floor
			// would otherwise round the commission to zero and make the
			// banker bet +EV (it wins more often than it loses, and ties
			// push), which the "never bet less than one commission unit"
			// rule exists to prevent.
			if float64(bet)*rules.BankerPayout < 1 {
				return "push", bet, nil
			}
			return "win", bet + bankerWin, nil
		}
	default:
		if spot == baccaratSpotTie {
			tieWin, err := MulPayout(bet, rules.TiePayout)
			if err != nil {
				return "win", bet + tieWin, err
			}
			return "win", bet + tieWin, nil
		}
		return "push", bet, nil
	}
	return "loss", 0, nil
}

func baccaratOutcomeMessage(playerTotal, bankerTotal int) string {
	switch {
	case playerTotal > bankerTotal:
		return fmt.Sprintf("Player wins %d over %d.", playerTotal, bankerTotal)
	case bankerTotal > playerTotal:
		return fmt.Sprintf("Banker wins %d over %d.", bankerTotal, playerTotal)
	default:
		return fmt.Sprintf("Player and banker tie at %d.", playerTotal)
	}
}

func baccaratResultMessages(name, result string, payout int) (string, string) {
	switch result {
	case "win":
		return name + " wins!", fmt.Sprintf("You win! +%d credits", payout)
	case "push":
		return name + " pushes.", fmt.Sprintf("You push. +%d credits", payout)
	default:
		return name + " loses.", "You lose!"
	}
}

// refundAll refunds every committed wager at this table (graceful
// shutdown/eviction): the wallet returns every outstanding stake exactly
// once. It then RESETS the round, so a refunded round can never settle (and
// pay) afterwards: calling it twice, or letting the table keep running,
// cannot pay the same round twice.
func (t *baccaratTable) refundAll() []Event {
	t.mu.Lock()
	defer t.mu.Unlock()
	events := t.refundAllLocked()
	t.resetRound()
	return events
}