casino/pkg/room/room_test.go

package room

import (
	"context"
	"fmt"
	"math/rand"
	"os"
	"sync"
	"testing"
	"time"

	"github.com/drjones/quantum-arcade/pkg/fair"
	"github.com/drjones/quantum-arcade/pkg/fixed"
	"github.com/drjones/quantum-arcade/pkg/ledger"
	"github.com/drjones/quantum-arcade/pkg/sim"
	"github.com/jackc/pgx/v5/pgxpool"
)

// These are internal tests so the state machine can be driven a step at a time
// instead of waiting on wall-clock timers.

var runID = fmt.Sprintf("%d-%d", time.Now().UnixNano(), rand.Int63())

func testPool(t *testing.T) *pgxpool.Pool {
	t.Helper()
	dsn := os.Getenv("ARCADE_TEST_DSN")
	if dsn == "" {
		dsn = "postgres://arcade:arcade_dev@localhost:5432/arcade"
	}
	pool, err := pgxpool.New(context.Background(), dsn)
	if err != nil {
		t.Skipf("no database available: %v", err)
	}
	if err := pool.Ping(context.Background()); err != nil {
		t.Skipf("no database available: %v", err)
	}
	return pool
}

type fixture struct {
	t      *testing.T
	room   *Room
	ledger *ledger.Ledger
	ctx    context.Context
}

func newFixture(t *testing.T) *fixture {
	t.Helper()
	pool := testPool(t)
	l := ledger.New(pool)
	return &fixture{
		t:      t,
		room:   New("rocket", pool, l),
		ledger: l,
		ctx:    context.Background(),
	}
}

// player creates a funded account and returns its id and public key.
func (f *fixture) player(label string, fundMsat int64) (int64, []byte) {
	f.t.Helper()
	pk := []byte(fmt.Sprintf("%s-%s-%s", runID, f.t.Name(), label))
	id, err := f.ledger.EnsurePlayer(f.ctx, pk)
	if err != nil {
		f.t.Fatal(err)
	}
	if fundMsat > 0 {
		if _, err := f.ledger.Deposit(f.ctx, id, fundMsat); err != nil {
			f.t.Fatal(err)
		}
	}
	return id, pk
}

// openBetting drives the room into an open betting window.
func (f *fixture) openBetting() {
	f.t.Helper()
	if err := f.room.openRound(f.ctx); err != nil {
		f.t.Fatal(err)
	}
}

// startRun locks the round and begins the climb.
func (f *fixture) startRun() {
	f.t.Helper()
	f.room.mu.Lock()
	f.room.state = StateLocked
	f.room.mu.Unlock()
	if err := f.room.startRunning(f.ctx); err != nil {
		f.t.Fatal(err)
	}
}

// forceCrashPoint pins the round's crash point so cash-out tests do not depend
// on a random draw. A genuine 1.00x crash is an instant bust where nobody can
// cash out, which is correct behaviour but useless for testing the cash-out
// path.
func (f *fixture) forceCrashPoint(multiplier int64) {
	f.t.Helper()
	f.room.mu.Lock()
	f.room.crashPoint = fixed.FromInt(multiplier)
	f.room.mu.Unlock()
}

// advanceTo moves the round to a specific tick without settling.
func (f *fixture) advanceTo(tick int) {
	f.t.Helper()
	f.room.mu.Lock()
	f.room.tick = tick
	f.room.mu.Unlock()
}

/* ---------------- lifecycle ---------------- */

func TestNewRoomStartsSettled(t *testing.T) {
	f := newFixture(t)
	if got := f.room.Snapshot().State; got != StateSettled {
		t.Fatalf("new room state = %q, want %q", got, StateSettled)
	}
}

func TestOpenRoundCommitsBeforeBetting(t *testing.T) {
	f := newFixture(t)
	f.openBetting()

	snap := f.room.Snapshot()
	if snap.State != StateBetting {
		t.Fatalf("state = %q, want betting_open", snap.State)
	}
	if snap.Commitment == "" {
		t.Fatal("no commitment published when betting opened")
	}
	// The seed must not leak while bets are still being taken.
	if snap.ServerSeed != "" {
		t.Fatal("server seed exposed during the betting window")
	}
	if snap.CrashPoint != "" {
		t.Fatal("crash point exposed during the betting window")
	}
}

func TestSeedRevealedOnlyAfterSettlement(t *testing.T) {
	f := newFixture(t)
	f.openBetting()
	f.startRun()

	if snap := f.room.Snapshot(); snap.ServerSeed != "" {
		t.Fatal("seed revealed while the round was running")
	}
	if err := f.room.settle(f.ctx); err != nil {
		t.Fatal(err)
	}
	snap := f.room.Snapshot()
	if snap.ServerSeed == "" {
		t.Fatal("seed not revealed after settlement")
	}
	if snap.CrashPoint == "" {
		t.Fatal("crash point not revealed after settlement")
	}
}

func TestEachRoundGetsAFreshSeed(t *testing.T) {
	f := newFixture(t)
	seen := map[string]bool{}
	for i := 0; i < 20; i++ {
		f.openBetting()
		c := f.room.Snapshot().Commitment
		if seen[c] {
			t.Fatalf("commitment reused on round %d", i)
		}
		seen[c] = true
	}
}

func TestNonceAdvancesPerRound(t *testing.T) {
	f := newFixture(t)
	f.openBetting()
	first := f.room.nonce
	f.openBetting()
	if f.room.nonce != first+1 {
		t.Fatalf("nonce went %d -> %d, want +1", first, f.room.nonce)
	}
}

/* ---------------- betting ---------------- */

func TestPlaceBetDebitsStakeImmediately(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 10_000)
	f.openBetting()

	before, _ := f.ledger.Balance(f.ctx, id)
	if err := f.room.PlaceBet(f.ctx, id, pk, "a", 3_000); err != nil {
		t.Fatal(err)
	}
	after, _ := f.ledger.Balance(f.ctx, id)
	if before-after != 3_000 {
		t.Fatalf("balance moved by %d, want 3000", before-after)
	}
}

func TestCannotBetOutsideBettingWindow(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 10_000)

	// Room starts settled.
	if err := f.room.PlaceBet(f.ctx, id, pk, "a", 1_000); err == nil {
		t.Fatal("bet accepted while settled")
	}

	f.openBetting()
	f.startRun()
	if err := f.room.PlaceBet(f.ctx, id, pk, "a", 1_000); err == nil {
		t.Fatal("bet accepted while running")
	}
}

func TestCannotBetTwiceInOneRound(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 10_000)
	f.openBetting()

	if err := f.room.PlaceBet(f.ctx, id, pk, "a", 1_000); err != nil {
		t.Fatal(err)
	}
	if err := f.room.PlaceBet(f.ctx, id, pk, "a", 1_000); err == nil {
		t.Fatal("second bet in the same round was accepted")
	}
}

func TestCannotBetMoreThanBalance(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 1_000)
	f.openBetting()

	if err := f.room.PlaceBet(f.ctx, id, pk, "a", 50_000); err == nil {
		t.Fatal("bet larger than balance was accepted")
	}
	// And nothing was taken.
	if bal, _ := f.ledger.Balance(f.ctx, id); bal != 1_000 {
		t.Fatalf("balance = %d after failed bet, want 1000", bal)
	}
}

func TestNonPositiveStakesRejected(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 10_000)
	f.openBetting()

	for _, stake := range []int64{0, -1, -5_000} {
		if err := f.room.PlaceBet(f.ctx, id, pk, "a", stake); err == nil {
			t.Fatalf("stake %d was accepted", stake)
		}
	}
}

/* ---------------- cash out ---------------- */

func TestCashOutOnlyWhileRunning(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 10_000)
	f.openBetting()
	if err := f.room.PlaceBet(f.ctx, id, pk, "a", 1_000); err != nil {
		t.Fatal(err)
	}

	if _, err := f.room.CashOut(id); err == nil {
		t.Fatal("cash out accepted during betting")
	}
	f.startRun()
	f.forceCrashPoint(100)
	if _, err := f.room.CashOut(id); err != nil {
		t.Fatalf("cash out rejected while running: %v", err)
	}
}

func TestCannotCashOutTwice(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 10_000)
	f.openBetting()
	_ = f.room.PlaceBet(f.ctx, id, pk, "a", 1_000)
	f.startRun()
	f.forceCrashPoint(100)

	if _, err := f.room.CashOut(id); err != nil {
		t.Fatal(err)
	}
	if _, err := f.room.CashOut(id); err == nil {
		t.Fatal("second cash out was accepted")
	}
}

func TestCannotCashOutWithoutABet(t *testing.T) {
	f := newFixture(t)
	id, _ := f.player("a", 10_000)
	f.openBetting()
	f.startRun()
	f.forceCrashPoint(100)

	if _, err := f.room.CashOut(id); err == nil {
		t.Fatal("cash out accepted with no bet placed")
	}
}

// Past the crash point there is nothing left to cash out.
func TestCannotCashOutAfterTheCrash(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 10_000)
	f.openBetting()
	_ = f.room.PlaceBet(f.ctx, id, pk, "a", 1_000)
	f.startRun()

	// Jump past the crash point without letting the loop settle.
	f.room.mu.Lock()
	target := sim.TicksToMultiplier(f.room.crashPoint)
	f.room.mu.Unlock()
	f.advanceTo(target + 5)

	if _, err := f.room.CashOut(id); err == nil {
		t.Fatal("cash out accepted after the crash point")
	}
}

/* ---------------- settlement ---------------- */

func TestCashedOutPlayerIsPaid(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 100_000)
	house, err := f.ledger.AccountByName(f.ctx, "house_pot")
	if err != nil {
		t.Fatal(err)
	}
	// Fund the house so it can cover the payout.
	hp, _ := f.player("housefund", 1_000_000)
	if _, err := f.ledger.Transfer(f.ctx, hp, house, 1_000_000); err != nil {
		t.Fatal(err)
	}

	f.openBetting()
	const stake = 10_000
	if err := f.room.PlaceBet(f.ctx, id, pk, "a", stake); err != nil {
		t.Fatal(err)
	}
	f.startRun()

	// Advance a little so the multiplier is meaningfully above 1.0, but stay
	// below the crash point.
	f.room.mu.Lock()
	crashTick := sim.TicksToMultiplier(f.room.crashPoint)
	f.room.mu.Unlock()
	if crashTick < 2 {
		t.Skip("crash point too low for this test; rerun")
	}
	f.advanceTo(crashTick - 1)

	at, err := f.room.CashOut(id)
	if err != nil {
		t.Fatal(err)
	}

	beforeSettle, _ := f.ledger.Balance(f.ctx, id)
	if err := f.room.settle(f.ctx); err != nil {
		t.Fatal(err)
	}
	afterSettle, _ := f.ledger.Balance(f.ctx, id)

	want := stake * int64(at) / int64(fixed.One)
	if afterSettle-beforeSettle != want {
		t.Fatalf("payout = %d, want %d (cashed out at %v)",
			afterSettle-beforeSettle, want, at)
	}
}

func TestPlayerWhoDidNotCashOutGetsNothing(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 100_000)

	f.openBetting()
	if err := f.room.PlaceBet(f.ctx, id, pk, "a", 10_000); err != nil {
		t.Fatal(err)
	}
	f.startRun()

	before, _ := f.ledger.Balance(f.ctx, id)
	if err := f.room.settle(f.ctx); err != nil {
		t.Fatal(err)
	}
	after, _ := f.ledger.Balance(f.ctx, id)
	if after != before {
		t.Fatalf("balance changed by %d for a player who never cashed out", after-before)
	}
}

// The books must balance across a full round with mixed outcomes.
func TestBooksBalanceAcrossAFullRound(t *testing.T) {
	f := newFixture(t)
	house, _ := f.ledger.AccountByName(f.ctx, "house_pot")
	hp, _ := f.player("housefund", 10_000_000)
	if _, err := f.ledger.Transfer(f.ctx, hp, house, 10_000_000); err != nil {
		t.Fatal(err)
	}

	f.openBetting()
	var ids []int64
	for i := 0; i < 5; i++ {
		id, pk := f.player(fmt.Sprintf("p%d", i), 100_000)
		if err := f.room.PlaceBet(f.ctx, id, pk, "p", 10_000); err != nil {
			t.Fatal(err)
		}
		ids = append(ids, id)
	}
	f.startRun()

	f.room.mu.Lock()
	crashTick := sim.TicksToMultiplier(f.room.crashPoint)
	f.room.mu.Unlock()
	if crashTick > 2 {
		f.advanceTo(crashTick - 1)
		// Half cash out, half ride it in.
		for i, id := range ids {
			if i%2 == 0 {
				if _, err := f.room.CashOut(id); err != nil {
					t.Fatalf("cash out %d: %v", i, err)
				}
			}
		}
	}

	if err := f.room.settle(f.ctx); err != nil {
		t.Fatal(err)
	}
	total, err := f.ledger.ConservationCheck(f.ctx)
	if err != nil {
		t.Fatal(err)
	}
	if total != 0 {
		t.Fatalf("books do not balance after settlement: %d", total)
	}
}

/* ---------------- fairness wiring ---------------- */

// The crash point must follow from the committed seed and the participant set,
// which is what makes the published proof meaningful.
func TestCrashPointDerivesFromCommittedSeedAndPlayers(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 100_000)

	f.openBetting()
	if err := f.room.PlaceBet(f.ctx, id, pk, "a", 1_000); err != nil {
		t.Fatal(err)
	}
	f.startRun()

	f.room.mu.RLock()
	seed := f.room.serverSeed
	nonce := f.room.nonce
	order := append([][]byte(nil), f.room.order...)
	actual := f.room.crashPoint
	f.room.mu.RUnlock()

	expected := sim.CrashPoint(fair.RoundSeed(seed, fair.ClientSeed(order), nonce))
	if actual != expected {
		t.Fatalf("crash point %v does not follow from the published inputs (want %v)",
			actual, expected)
	}
}

func TestAddingAPlayerChangesTheOutcome(t *testing.T) {
	f := newFixture(t)
	_, pkA := f.player("a", 100_000)
	_, pkB := f.player("b", 100_000)

	seed := fair.NewServerSeed()
	one := sim.CrashPoint(fair.RoundSeed(seed, fair.ClientSeed([][]byte{pkA}), 1))
	two := sim.CrashPoint(fair.RoundSeed(seed, fair.ClientSeed([][]byte{pkA, pkB}), 1))
	if one == two {
		t.Fatal("a second participant did not affect the outcome")
	}
}

/* ---------------- broadcast ---------------- */

func TestSubscriberReceivesUpdates(t *testing.T) {
	f := newFixture(t)
	ch, unsubscribe := f.room.Subscribe()
	defer unsubscribe()

	f.openBetting()

	select {
	case snap := <-ch:
		if snap.State != StateBetting {
			t.Fatalf("received state %q, want betting_open", snap.State)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("subscriber received no update")
	}
}

// A phone that stops reading must not stall the round for everyone else.
func TestSlowSubscriberDoesNotBlockTheRoom(t *testing.T) {
	f := newFixture(t)
	_, unsubscribe := f.room.Subscribe() // never drained
	defer unsubscribe()

	done := make(chan struct{})
	go func() {
		for i := 0; i < 200; i++ {
			f.room.broadcast()
		}
		close(done)
	}()

	select {
	case <-done:
	case <-time.After(3 * time.Second):
		t.Fatal("broadcast blocked on a subscriber that stopped reading")
	}
}

func TestUnsubscribeStopsDelivery(t *testing.T) {
	f := newFixture(t)
	ch, unsubscribe := f.room.Subscribe()
	unsubscribe()

	// The channel is closed, so a receive returns immediately with ok == false.
	select {
	case _, ok := <-ch:
		if ok {
			t.Fatal("received a value after unsubscribing")
		}
	case <-time.After(time.Second):
		t.Fatal("channel was not closed by unsubscribe")
	}
}

/* ---------------- concurrency ---------------- */

// Many players betting at once must all be recorded, with no lost updates and
// no double-charging.
func TestConcurrentBetsAreAllRecorded(t *testing.T) {
	f := newFixture(t)
	f.openBetting()

	const players = 12
	type acct struct {
		id int64
		pk []byte
	}
	accts := make([]acct, players)
	for i := range accts {
		id, pk := f.player(fmt.Sprintf("c%d", i), 100_000)
		accts[i] = acct{id, pk}
	}

	var wg sync.WaitGroup
	errs := make([]error, players)
	for i, a := range accts {
		wg.Add(1)
		go func(i int, a acct) {
			defer wg.Done()
			errs[i] = f.room.PlaceBet(f.ctx, a.id, a.pk, "c", 5_000)
		}(i, a)
	}
	wg.Wait()

	for i, err := range errs {
		if err != nil {
			t.Fatalf("player %d could not bet: %v", i, err)
		}
	}
	if got := len(f.room.Snapshot().Players); got != players {
		t.Fatalf("%d players in the round, want %d", got, players)
	}
	for _, a := range accts {
		bal, _ := f.ledger.Balance(f.ctx, a.id)
		if bal != 95_000 {
			t.Fatalf("account %d balance = %d, want 95000", a.id, bal)
		}
	}
}

// Concurrent cash-outs by the same player must yield exactly one success.
func TestConcurrentCashOutsYieldOne(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 100_000)
	f.openBetting()
	_ = f.room.PlaceBet(f.ctx, id, pk, "a", 5_000)
	f.startRun()
	f.forceCrashPoint(100)

	const attempts = 10
	var wg sync.WaitGroup
	results := make([]error, attempts)
	for i := 0; i < attempts; i++ {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			_, results[i] = f.room.CashOut(id)
		}(i)
	}
	wg.Wait()

	successes := 0
	for _, err := range results {
		if err == nil {
			successes++
		}
	}
	if successes != 1 {
		t.Fatalf("%d concurrent cash-outs succeeded, want 1", successes)
	}
}

/* ---------------- snapshot ---------------- */

func TestSnapshotReportsCashOutMultiplier(t *testing.T) {
	f := newFixture(t)
	id, pk := f.player("a", 100_000)
	f.openBetting()
	_ = f.room.PlaceBet(f.ctx, id, pk, "nick", 5_000)
	f.startRun()
	f.forceCrashPoint(100)

	if _, err := f.room.CashOut(id); err != nil {
		t.Fatal(err)
	}
	snap := f.room.Snapshot()
	if len(snap.Players) != 1 {
		t.Fatalf("%d players in snapshot, want 1", len(snap.Players))
	}
	if snap.Players[0].CashedOut == "" {
		t.Fatal("snapshot does not show the cash-out")
	}
	if snap.Players[0].Nickname != "nick" {
		t.Fatalf("nickname = %q, want %q", snap.Players[0].Nickname, "nick")
	}
}

func TestMultiplierStartsAtOneEachRound(t *testing.T) {
	f := newFixture(t)
	f.openBetting()
	if got := f.room.Snapshot().Multiplier; got != fixed.One.String() {
		t.Fatalf("multiplier at round open = %s, want %s", got, fixed.One.String())
	}
}