path: root/internal/casino/machine.go

package casino

import (
	"fmt"
	"math"
	"math/rand"
	"sync"
)

type machinePhase string

const (
	machineReady    machinePhase = "ready"
	machineSpinning machinePhase = "spinning"
	machinePayout   machinePhase = "payout"
	payoutDelay                  = 2
)

type Machine struct {
	mu              sync.Mutex
	RoomID          int
	Config          MachineConfig
	player          *Participant
	bet             int
	phase           machinePhase
	spin            *SlotSpin
	reel            int
	clock           int
	freeSpins       int
	inFreeSpins     bool
	spinBet         int
	payoutRemainder float64
	// stakeID is the wallet handle of the wager committed to the current
	// round (the triggering wager for a free-spin feature). Resolving by
	// handle — not the player-wide ResolveStakes — consumes only this
	// round's stake, leaving an older failed-payout stake pending.
	stakeID string
	// featureBank holds the winnings of a paid round whose free-spin feature
	// is still running. They are paid as ONE settlement when the feature
	// ends: see finishSpin for why the triggering stake stays pending until
	// then.
	featureBank   float64
	profile       SlotProfile
	rng           *rand.Rand
	suspense      bool
	autoBet       bool
	autoCountdown int
	// stakeFailed marks the in-flight stake whose payout could not be
	// persisted: the stake stays pending, so the seat must not consume
	// (forfeit) it when the player leaves — a refund or startup recovery
	// returns it.
	stakeFailed bool
}

func newMachine(roomID int, cfg MachineConfig, rng *rand.Rand) *Machine {
	cfg = cfg.Normalize()
	return &Machine{RoomID: roomID, Config: cfg, phase: machineReady, profile: machineSlotProfile(cfg), rng: rng}
}

func (m *Machine) join(name string) []Event {
	m.mu.Lock()
	defer m.mu.Unlock()
	if m.player != nil {
		return []Event{{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult, PrivateTo: name, Message: "That slot machine is occupied."}}
	}
	m.player = &Participant{Name: name, Connected: true}
	events := []Event{{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventJoined, Player: name,
		Message:        fmt.Sprintf("%s sits down at the slots machine.", name),
		PrivateMessage: "You sit down at the slot machine.", PrivateTo: name, Color: "casino_action", Public: true}}
	return append(events, m.privateMenu("You sit down at the slot machine.")...)
}

func (m *Machine) setBet(name string, amount int, wallet Wallet) []Event {
	m.mu.Lock()
	defer m.mu.Unlock()
	if !m.owns(name) {
		return m.privateTo(name, "You aren't playing at a slot machine.")
	}
	if m.autoBet {
		return m.private("Autobet is active. Type \"stop\" to stop playing.")
	}
	if m.phase != machineReady {
		return m.private("You're in the middle of a spin!")
	}
	if amount < m.Config.MinBet || amount > m.Config.MaxBet {
		return m.private(fmt.Sprintf("Slot machine bets must be %s.", betRangeText(m.Config.MinBet, m.Config.MaxBet)))
	}
	return m.beginSpinLocked(amount, wallet,
		fmt.Sprintf("%s sets the bet to %d and pulls the lever.", name, amount),
		fmt.Sprintf("Bet set to %d. You pull the lever on the slots machine.", amount))
}

func (m *Machine) start(name string, wallet Wallet) []Event {
	m.mu.Lock()
	defer m.mu.Unlock()
	if !m.owns(name) {
		return m.privateTo(name, "You aren't playing at a slot machine.")
	}
	if m.autoBet {
		return m.private("Autobet is active. Type \"stop\" to stop playing.")
	}
	if m.phase != machineReady {
		return m.private("You're in the middle of a spin!")
	}
	if m.bet <= 0 {
		return m.private("Set a wager first with 'bet <amount>'.")
	}
	return m.beginSpinLocked(m.bet, wallet,
		fmt.Sprintf("%s pulls the lever on the slots machine.", name),
		"You pull the lever on the slots machine.")
}

func (m *Machine) beginSpinLocked(amount int, wallet Wallet, publicMessage, privateMessage string) []Event {
	wager, err := wallet.Wager(amount)
	if err != nil {
		return m.private(walletErrorMessage(err, "You don't have enough chips and credits for that bet."))
	}
	m.bet = amount
	m.spinBet = amount
	m.stakeID = wager.ID
	m.player.Wallet = wallet
	m.stakeFailed = false
	m.spin = generateSlotSpinWithProfile(m.rng, m.spinBet, m.profile)
	m.reel, m.clock, m.suspense = 0, 0, false
	m.phase = machineSpinning
	return m.playerAction(publicMessage, privateMessage)
}

func (m *Machine) enableAutoBet(name string, wallet Wallet) []Event {
	m.mu.Lock()
	defer m.mu.Unlock()
	if !m.owns(name) {
		return m.privateTo(name, "You aren't playing at a slot machine.")
	}
	if m.autoBet {
		return m.private("Autobet is already active.")
	}
	if m.phase != machineReady {
		return m.private("You're in the middle of a spin!")
	}
	if m.bet <= 0 {
		return m.private("Set a wager first with 'bet <amount>'.")
	}
	m.player.Wallet = wallet
	m.autoBet = true
	m.autoCountdown = 0
	return nil
}

func (m *Machine) stopAutoBet(name string) ([]Event, bool) {
	m.mu.Lock()
	defer m.mu.Unlock()
	if !m.owns(name) || !m.autoBet {
		return nil, false
	}
	m.autoBet = false
	m.autoCountdown = 0
	return m.private("Autobet stopped. You remain at the slot machine."), true
}

func (m *Machine) tick() []Event {
	m.mu.Lock()
	defer m.mu.Unlock()
	if m.autoBet && m.player == nil {
		// Defensive: autobet can never run without a seated player.
		m.autoBet, m.autoCountdown = false, 0
	}
	if m.phase == machineReady && m.autoBet {
		return m.autoBetTick()
	}
	if (m.phase != machineSpinning && m.phase != machinePayout) || m.spin == nil {
		return nil
	}
	if m.phase == machinePayout {
		m.clock++
		if m.clock < payoutDelay {
			return nil
		}
		m.clock = 0
		m.phase = machineReady
		return m.finishSpin()
	}
	m.clock++
	delay := m.Config.SpinTicks
	if m.suspense && delay < 4 {
		delay = 4
	}
	if m.clock < delay {
		return nil
	}
	m.clock = 0
	m.reel++
	message := fmt.Sprintf("Reel %d stops...", m.reel)
	events := m.publicSlot(message, m.reel)
	if m.reel < slotGridReels && stoppedScatters(m.spin.Grid, m.reel, m.profile.FreeSpinTrigger) >= 2 && !m.suspense {
		m.suspense = true
		events = append(events, m.public("Two scatters! The remaining reels slow down...")...)
	}
	if m.reel < slotGridReels {
		return events
	}
	m.phase = machinePayout
	m.clock = 0
	return events
}

func (m *Machine) autoBetTick() []Event {
	m.autoCountdown++
	switch m.autoCountdown {
	case 1:
		return m.private("Autobet enabled!")
	case 2:
		return m.private(`Type "stop" to stop playing`)
	case 3:
		m.autoCountdown = 0
		if m.bet <= 0 || m.player.Wallet == nil {
			m.autoBet = false
			return m.private("Autobet stopped: no wager is set.")
		}
		if wager, err := m.player.Wallet.Wager(m.bet); err != nil {
			m.autoBet = false
			return m.private(walletErrorMessage(err, "Autobet stopped: you don't have enough chips and credits for that bet."))
		} else {
			m.stakeID = wager.ID
		}
		m.spinBet = m.bet
		m.stakeFailed = false
		m.spin = generateSlotSpinWithProfile(m.rng, m.spinBet, m.profile)
		m.reel, m.clock, m.suspense = 0, 0, false
		m.phase = machineSpinning
		return m.playerAction(fmt.Sprintf("%s starts an automatic spin.", m.player.Name), fmt.Sprintf("Betting... %d credits.", m.bet))
	default:
		return nil
	}
}

// finishSpin resolves the spin that just stopped: it pays that spin's
// winnings, advances or starts the free-spin feature, and resolves the
// triggering stake once the whole round (feature included) is over.
//
// A free-spin feature pays out as ONE settlement when it ends. While the
// feature runs its winnings are banked in memory and the triggering stake
// stays PENDING (nothing is resolved): paying a free spin as it landed would
// consume the stake early, so a crash mid-feature would eat it instead of
// refunding it. Banking the winnings keeps the refund-on-lost-round behavior
// intact until the feature completes.
func (m *Machine) finishSpin() []Event {
	events := []Event{}
	result := m.spin.Payout + m.payoutRemainder
	// Checked conversion: a runaway profile or overflow must clamp at the
	// economy cap instead of wrapping through a machine-sized int. A NaN or
	// negative result is a corrupt computation, not a jackpot: clamp it to
	// zero (fail closed) rather than up to the economy ceiling (fail open).
	if math.IsNaN(result) || result < 0 {
		result = 0
	} else if result > MaxCredits {
		result = MaxCredits
	}
	credits := int(math.Floor(result))
	m.payoutRemainder = result - float64(credits)

	// A spin belongs to a feature when it is a free spin or when it just
	// triggered one; the feature (and with it the round) resolves on the
	// last free spin.
	triggered := m.spin.ScatterCount >= 3 && m.freeSpins == 0 && !m.inFreeSpins
	inFeature := m.inFreeSpins || triggered
	featureEnds := m.inFreeSpins && m.freeSpins == 0
	payNow := credits
	switch {
	case inFeature && !featureEnds:
		m.featureBank += float64(credits)
		payNow = 0
	case featureEnds:
		payNow = credits + int(m.featureBank)
		m.featureBank = 0
	}

	payFailed := false
	if payNow > 0 && m.player.Wallet != nil {
		// Credit the payout and consume the triggering stake in ONE save: a
		// crash can then never pay the win AND refund the same stake.
		if err := m.player.Wallet.PayCredits(payNow, m.stakeID); err != nil {
			// The payout could not be made durable. Do not announce the win as
			// paid, stop any autobet chain, and keep the stake PENDING
			// (stakeFailed): the settlement was never durable, so the stake is
			// refunded rather than paid.
			payFailed = true
			m.stakeFailed = true
			m.autoBet, m.autoCountdown = false, 0
			failedEvents := m.private(payoutFailedMessage())
			failedEvents[0].Color = "casino_payout"
			events = append(events, failedEvents...)
		}
	}
	if payNow > 0 && !payFailed {
		message := fmt.Sprintf("\nYou win %d credits.", payNow)
		switch {
		case inFeature && !featureEnds:
			// Banked, not spent: say so, or the player would read the win
			// as already in their balance.
			message = fmt.Sprintf("\nYou win %d credits, paid when the free spins end.", payNow)
		case featureEnds:
			message = fmt.Sprintf("\nThe free spins pay %d credits.", payNow)
		}
		winEvents := m.private(message)
		winEvents[0].Color = "casino_result_win"
		if payNow > m.spinBet {
			winEvents[0].Color = "casino_big_win"
		}
		events = append(events, winEvents...)
	}
	if len(m.spin.Wins) > 0 {
		winEvents := m.private(formatWins(m.spin.Wins, m.profile.Ways))
		winEvents[0].Color = "casino_win"
		events = append(events, winEvents...)
	}
	// A paid feature in progress never retriggers: scatters landing during a
	// free spin are ignored, matching the CalculateRTP model (the feature is
	// a fixed number of automatic spins). Retriggering only on a paid spin
	// keeps the machine's actual return aligned with that model.
	if triggered {
		m.freeSpins = m.profile.FreeSpinCount
		m.inFreeSpins = true
		events = append(events, m.public(fmt.Sprintf("Three scatter symbols trigger %d free spins!", m.profile.FreeSpinCount))...)
	}
	if m.freeSpins > 0 {
		// A feature is in progress: the triggering stake stays PENDING until
		// the bonus completes, so a graceful shutdown (or crash) while free
		// spins remain refunds the stake through RefundOutstanding / startup
		// recovery instead of silently eating the feature.
		m.freeSpins--
		m.phase = machineSpinning
		m.spin = generateSlotSpinWithProfile(m.rng, m.spinBet, m.profile)
		m.reel, m.clock, m.suspense = 0, 0, false
		events = append(events, m.public(fmt.Sprintf("%d free spins remain.", m.freeSpins))...)
	} else {
		m.inFreeSpins = false
		if !payFailed && m.player.Wallet != nil {
			// A win already consumed this round's stake inside PayCredits; a
			// loss (payNow == 0) has not, so consume it here. Either way the
			// round is over and the stake must not be refunded.
			m.player.Wallet.ResolveStake(m.stakeID)
			m.stakeID = ""
			m.stakeFailed = false
		}
		if !m.autoBet {
			events = append(events, m.privateMenu("")...)
		}
	}
	return events
}

func (m *Machine) leave(name string) []Event {
	m.mu.Lock()
	defer m.mu.Unlock()
	if !m.owns(name) {
		return nil
	}
	if m.phase != machineReady {
		return m.private("You're in the middle of a spin!")
	}
	m.resetSeat()
	return []Event{{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventLeft, Player: name,
		Message: fmt.Sprintf("%s stands up from the slots machine.", name), PrivateMessage: "You stand up from the slot machine.", PrivateTo: name, Color: "casino_action", Public: true}}
}

// resetSeat frees the machine, discarding any in-flight spin and autobet
// state. A wager already taken for a spin in progress is forfeited: its
// stake is consumed so it is not refunded. The exception is a stake whose
// payout could not be persisted (stakeFailed): it is left pending for a
// shutdown refund or startup recovery.
func (m *Machine) resetSeat() {
	if m.player != nil && m.player.Wallet != nil && !m.stakeFailed {
		m.player.Wallet.ResolveStake(m.stakeID)
	}
	m.player = nil
	m.bet = 0
	m.spin = nil
	m.spinBet = 0
	m.stakeID = ""
	m.phase = machineReady
	m.reel, m.clock, m.suspense = 0, 0, false
	m.freeSpins = 0
	m.inFreeSpins = false
	m.payoutRemainder = 0
	m.featureBank = 0
	m.autoBet, m.autoCountdown = false, 0
	m.stakeFailed = false
}

// markDisconnected removes the player from the machine, forfeiting any
// in-flight wager, so the seat is immediately free for someone else.
//
// Already-landed free-spin winnings (featureBank) are NOT part of the
// in-flight wager: they are settled after resetSeat consumes the triggering
// stake. If the round's payout could not be persisted (stakeFailed), the
// stake is left pending and the bank is reported as forfeited rather than
// silently destroyed.
func (m *Machine) markDisconnected(name string) []Event {
	m.mu.Lock()
	defer m.mu.Unlock()
	if !m.owns(name) {
		return nil
	}
	// A spin whose reels have all stopped has already been revealed to the
	// player, so its result is final. Settle it through the normal path
	// before the seat is reset: otherwise a disconnect during the cosmetic
	// payout delay forfeits an already-shown win and consumes the stake for a
	// spin the player watched land. finishSpin consumes the stake itself on a
	// resolved round (or banks a feature win), so resetSeat below neither
	// double-pays nor double-consumes.
	var events []Event
	if m.phase == machinePayout && m.spin != nil {
		events = append(events, m.finishSpin()...)
	}
	bank := int(m.featureBank)
	wallet := m.player.Wallet
	stakeFailed := m.stakeFailed
	m.resetSeat()
	events = append(events, Event{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventLeft, Player: name,
		Message: fmt.Sprintf("%s stands up from the slots machine.", name), Color: "casino_action", Public: true})
	if bank <= 0 || wallet == nil {
		return events
	}
	switch {
	case stakeFailed:
		events = append(events, Event{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult,
			PrivateTo: name, Player: name,
			PrivateMessage: fmt.Sprintf("Your %d credits of banked free-spin winnings were forfeited because the round could not be persisted.", bank),
			Color:          "casino_action", Public: false})
	case wallet.PayCredits(bank) != nil:
		events = append(events, Event{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult,
			PrivateTo: name, Player: name,
			PrivateMessage: fmt.Sprintf("Your %d credits of free-spin winnings could not be persisted; they were forfeited.", bank),
			Color:          "casino_action", Public: false})
	default:
		events = append(events, Event{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult,
			PrivateTo: name, Player: name,
			Message:        fmt.Sprintf("%s's %d banked free-spin credits pay out on disconnect.", name, bank),
			PrivateMessage: fmt.Sprintf("The house settles your %d banked free-spin winnings.", bank),
			Color:          "casino_action", Public: true})
	}
	return events
}

func (m *Machine) hasParticipant(name string) bool {
	m.mu.Lock()
	defer m.mu.Unlock()
	return m.owns(name)
}

func (m *Machine) isBusy(name string) bool {
	m.mu.Lock()
	defer m.mu.Unlock()
	return m.owns(name) && (m.autoBet || m.phase == machineSpinning || m.phase == machinePayout)
}

func (m *Machine) owns(name string) bool { return m.player != nil && m.player.Name == name }

func (m *Machine) private(message string) []Event {
	return m.privateTo(m.player.Name, message)
}

func (m *Machine) privateTo(name, message string) []Event {
	return []Event{{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult, PrivateTo: name, Message: message, Color: "casino_action"}}
}

func (m *Machine) public(message string) []Event {
	return []Event{{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult, Player: m.player.Name, Message: message, Color: "casino_action", Public: true}}
}

func (m *Machine) playerAction(publicMessage, privateMessage string) []Event {
	return []Event{{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult, Player: m.player.Name,
		Message: publicMessage, PrivateMessage: privateMessage, PrivateTo: m.player.Name, Color: "casino_action", Public: true}}
}

func (m *Machine) publicSlot(message string, stopped int) []Event {
	return []Event{{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult, Player: m.player.Name,
		Message: message, Color: "casino_action", Public: true, Snapshot: &SlotSnapshot{Grid: m.spin.Grid, StoppedReels: stopped}}}
}

func stoppedScatters(grid [slotGridRows][slotGridReels]string, reels int, trigger string) int {
	count := 0
	for row := 0; row < slotGridRows; row++ {
		for reel := 0; reel < reels && reel < slotGridReels; reel++ {
			if grid[row][reel] == trigger {
				count++
			}
		}
	}
	return count
}

func formatWins(wins []SlotWin, ways int) string {
	message := fmt.Sprintf("Winning lines/ways (%d-way evaluation):\n", ways)
	for _, win := range wins {
		message += fmt.Sprintf("  %s x%d: %d ways x %.4gx bet / %d = %.4f credits\n", win.Symbol, win.Length, win.Ways, win.Multiplier, ways, win.Payout)
	}
	return message[:len(message)-1]
}

var slotCommands = []MenuCommand{
	{Command: "bet <amount>", Desc: "Set your wager"},
	{Command: "bet max", Desc: "Set the maximum wager"},
	{Command: "spin", Desc: "Spin using your current wager"},
	{Command: "autospin", Desc: "Start automatic betting"},
	{Command: "stop", Desc: "Leave the slot machine"},
}

func (m *Machine) privateMenu(prefix string) []Event {
	events := m.private(prefix)
	events[0].Color = "casino_menu"
	if m.phase == machineReady {
		events[0].Menu = &MenuView{Heading: prefix, ShowBalance: true, Commands: slotCommands}
	}
	return events
}

// refundAll refunds any pending stake at graceful shutdown/eviction and then
// DISCARDS the round (the machine closes with the process). RefundOutstanding
// returns every pending stake exactly once; a completed spin has none and is
// not refunded again. A stake whose payout could not be persisted
// (stakeFailed) is left pending by RefundOutstanding and returned here, since
// the settlement never became durable. A bonus in progress keeps its
// triggering stake pending, so a shutdown during the feature returns the
// stake (only the still-unplayed free spins' EV is forfeit); winnings that
// have already landed are banked in featureBank and paid through the wallet,
// so a graceful shutdown preserves them. Locked.
//
// Discarding the round is what makes the call safe to repeat: a refunded
// round can never settle (and pay its spin) afterwards, so neither a second
// RefundAll nor a stray tick can pay the same round twice.
func (m *Machine) refundAll() []Event {
	m.mu.Lock()
	defer m.mu.Unlock()
	if m.player == nil || m.player.Wallet == nil {
		return nil
	}
	name, wallet := m.player.Name, m.player.Wallet
	// Free-spin winnings that have already landed live only in featureBank
	// until the feature ends (see finishSpin), so discarding the round must
	// settle them or a graceful shutdown silently destroys them. Refund the
	// pending triggering stake FIRST, then pay the bank: the two are separate
	// (the stake is returned because the feature never completed, the bank is
	// winnings already won).
	chips, credits, err := wallet.RefundOutstanding()
	refund := chips + credits
	bank := int(m.featureBank)
	bankFailed := false
	if err == nil && bank > 0 {
		// Only settle the bank once the refund is durable: on a failed refund
		// the stake stays pending, and paying the bank first would leave the
		// two obligations tangled.
		if payErr := wallet.PayCredits(bank); payErr != nil {
			bankFailed = true
		}
	}
	// A refund that could not be made durable leaves the stakes pending; the
	// round is still discarded, and marking the stake as failed keeps
	// resetSeat from consuming (forfeiting) it. This is LOAD-BEARING, not
	// dead code: on the RefundOutstanding error path the stakes are left
	// pending, and resetSeat's guard is the only thing that stops it from
	// consuming them.
	m.stakeFailed = err != nil
	m.resetSeat()
	var events []Event
	switch {
	case err != nil:
		events = append(events, Event{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult,
			PrivateTo: name, Player: name,
			PrivateMessage: "Shutdown refund could not be persisted; the stake stays pending for the next startup.",
			Color:          "casino_action", Public: false})
	case refund > 0:
		events = append(events, Event{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult,
			PrivateTo: name, Player: name,
			Message:        fmt.Sprintf("%s is refunded %d as the casino closes.", name, refund),
			PrivateMessage: fmt.Sprintf("The house refunds your %d stake for the shutdown.", refund),
			Color:          "casino_action", Public: true})
	}
	// Announce the banked free-spin settlement, or its loss. resetSeat has
	// already zeroed featureBank by this point, so a failed refund does NOT
	// keep the bank in memory: the banked winnings are forfeited and only the
	// trigger stake is recovered. Report that forfeiture explicitly (a
	// stake-linked settlement that survives a failed shutdown refund is not
	// implemented) instead of dropping it silently.
	switch {
	case bankFailed:
		events = append(events, Event{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult,
			PrivateTo: name, Player: name,
			PrivateMessage: fmt.Sprintf("Your %d credits of free-spin winnings could not be persisted; they were forfeited.", bank),
			Color:          "casino_action", Public: false})
	case err != nil && bank > 0:
		events = append(events, Event{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult,
			PrivateTo: name, Player: name,
			PrivateMessage: fmt.Sprintf("Your %d credits of banked free-spin winnings were forfeited because the shutdown refund could not be persisted.", bank),
			Color:          "casino_action", Public: false})
	case err == nil && bank > 0:
		events = append(events, Event{RoomID: m.RoomID, TableID: m.Config.ID, Type: EventResult,
			PrivateTo: name, Player: name,
			Message:        fmt.Sprintf("%s's %d free-spin credits pay out as the casino closes.", name, bank),
			PrivateMessage: fmt.Sprintf("The house settles your %d banked free-spin winnings for the shutdown.", bank),
			Color:          "casino_action", Public: true})
	}
	return events
}

// idle reports whether no player is seated: only an idle machine may have
// its live rules replaced by new room configuration.
func (m *Machine) idle() bool {
	m.mu.Lock()
	defer m.mu.Unlock()
	return m.player == nil
}