ruby-sea-battle/game-server/internal/game/manager_test.go

package game

import (
	"context"
	"encoding/json"
	"sync"
	"testing"
	"time"

	"github.com/golang-jwt/jwt/v5"

	"github.com/ruby-sea-battle/game-server/internal/auth"
	"github.com/ruby-sea-battle/game-server/internal/protocol"
)

type fakeConn struct {
	mu        sync.Mutex
	sent      [][]byte
	closed    bool
	closeCode int
}

func (f *fakeConn) Send(_ context.Context, data []byte) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	cp := make([]byte, len(data))
	copy(cp, data)
	f.sent = append(f.sent, cp)
	return nil
}

func (f *fakeConn) Close(code int, _ string) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.closed = true
	f.closeCode = code
	return nil
}

func (f *fakeConn) messages() [][]byte {
	f.mu.Lock()
	defer f.mu.Unlock()
	out := make([][]byte, len(f.sent))
	copy(out, f.sent)
	return out
}

func (f *fakeConn) isClosed() (bool, int) {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.closed, f.closeCode
}

func claims(exp time.Time) *auth.GameClaims {
	return &auth.GameClaims{
		MatchID:    "match-1",
		Player1ID:  10,
		Player2ID:  20,
		GameServer: "ws://game.example.com/ws",
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(exp),
		},
	}
}

func parseMsg(t *testing.T, data []byte) []any {
	t.Helper()
	var v []any
	if err := json.Unmarshal(data, &v); err != nil {
		t.Fatalf("unmarshal %s: %v", data, err)
	}
	return v
}

func TestJoinFirstPlayerWaits(t *testing.T) {
	m := NewManager(time.Minute)
	c1 := &fakeConn{}
	gc := claims(time.Now().Add(time.Hour))

	_, idx, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join: %v", err)
	}
	if idx != 0 {
		t.Fatalf("slot = %d, want 0", idx)
	}
	if got := len(c1.messages()); got != 0 {
		t.Fatalf("first player got %d messages, want 0", got)
	}
}

func TestSecondJoinStartsMatch(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	if _, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID); err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, idx, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	} else if idx != 1 {
		t.Fatalf("slot = %d, want 1", idx)
	}

	for i, c := range []*fakeConn{c1, c2} {
		msgs := c.messages()
		if len(msgs) != 1 {
			t.Fatalf("player %d got %d messages, want 1", i, len(msgs))
		}
		v := parseMsg(t, msgs[0])
		// [3, seq, StatePlacingShips]
		if v[0] != float64(protocol.OpState) || v[1] != float64(1) || v[2] != float64(protocol.StatePlacingShips) {
			t.Fatalf("player %d got unexpected message: %v", i, v)
		}
	}
}

func TestJoinTimeoutEndsMatch(t *testing.T) {
	m := NewManager(50 * time.Millisecond)
	gc := claims(time.Now().Add(time.Hour))
	c1 := &fakeConn{}

	if _, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID); err != nil {
		t.Fatalf("join: %v", err)
	}

	deadline := time.Now().Add(2 * time.Second)
	for {
		if closed, _ := c1.isClosed(); closed {
			break
		}
		if time.Now().After(deadline) {
			t.Fatal("timed out waiting for the match to end")
		}
		time.Sleep(10 * time.Millisecond)
	}

	msgs := c1.messages()
	if len(msgs) != 1 {
		t.Fatalf("got %d messages, want 1", len(msgs))
	}
	v := parseMsg(t, msgs[0])
	// [2, seq, -1, "join timeout exceeded"]
	if v[0] != float64(protocol.OpEnd) || v[1] != float64(1) || v[2] != float64(protocol.EndCodeJoinTimeout) || v[3] != "join timeout exceeded" {
		t.Fatalf("unexpected END message: %v", v)
	}
	if closed, code := c1.isClosed(); !closed || code != protocol.CloseCodeNormal {
		t.Fatalf("conn closed=%v code=%d, want closed with %d", closed, code, protocol.CloseCodeNormal)
	}
}

func TestJoinAfterFinishReplaysEnd(t *testing.T) {
	m := NewManager(50 * time.Millisecond)
	gc := claims(time.Now().Add(time.Hour))
	c1 := &fakeConn{}

	if _, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID); err != nil {
		t.Fatalf("join: %v", err)
	}
	time.Sleep(200 * time.Millisecond) // let the join timer fire

	// A late join with the same (still valid) token must not create a new
	// match; the stored END is replayed instead. This also works for the
	// player who never connected at all.
	for _, userID := range []int64{gc.Player1ID, gc.Player2ID} {
		c := &fakeConn{}
		_, _, err := m.Join(context.Background(), c, gc, userID)
		if err != ErrMatchFinished {
			t.Fatalf("join after finish: err = %v, want ErrMatchFinished", err)
		}
		msgs := c.messages()
		if len(msgs) != 1 {
			t.Fatalf("replayed %d messages, want 1", len(msgs))
		}
		v := parseMsg(t, msgs[0])
		if v[0] != float64(protocol.OpEnd) || v[2] != float64(protocol.EndCodeJoinTimeout) {
			t.Fatalf("unexpected replayed message: %v", v)
		}
		if closed, _ := c.isClosed(); !closed {
			t.Fatal("connection was not closed after replaying END")
		}
	}
}

func TestReconnectReplacesConnection(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	old, c2 := &fakeConn{}, &fakeConn{}

	if _, _, err := m.Join(context.Background(), old, gc, gc.Player1ID); err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}
	// Game started: both got STATE, nobody acknowledged it yet.

	// Player 1 reconnects: old connection must be closed, the unacknowledged
	// STATE must be replayed to the new one.
	fresh := &fakeConn{}
	if _, idx, err := m.Join(context.Background(), fresh, gc, gc.Player1ID); err != nil {
		t.Fatalf("rejoin p1: %v", err)
	} else if idx != 0 {
		t.Fatalf("slot = %d, want 0", idx)
	}

	if closed, code := old.isClosed(); !closed || code != protocol.CloseCodeReplaced {
		t.Fatalf("old conn closed=%v code=%d, want closed with %d", closed, code, protocol.CloseCodeReplaced)
	}
	msgs := fresh.messages()
	if len(msgs) != 1 {
		t.Fatalf("replayed %d messages, want 1", len(msgs))
	}
	v := parseMsg(t, msgs[0])
	if v[0] != float64(protocol.OpState) || v[2] != float64(protocol.StatePlacingShips) {
		t.Fatalf("unexpected replayed message: %v", v)
	}

	// Leave with the old connection must not detach the new one.
	m.Leave(old, mustMatch(t, m, gc.MatchID), 0)
	m.Leave(fresh, mustMatch(t, m, gc.MatchID), 0)
}

func TestAckThenReconnectResendsCurrentState(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}

	// Player 1 acknowledges the STATE message, then reconnects. The queue
	// is empty, so the server re-sends the current state with a fresh seq.
	if err := m.Ack(match, 0, 1); err != nil {
		t.Fatalf("ack: %v", err)
	}

	fresh := &fakeConn{}
	if _, _, err := m.Join(context.Background(), fresh, gc, gc.Player1ID); err != nil {
		t.Fatalf("rejoin p1: %v", err)
	}
	msgs := fresh.messages()
	if len(msgs) != 1 {
		t.Fatalf("got %d messages, want 1", len(msgs))
	}
	v := parseMsg(t, msgs[0])
	if v[0] != float64(protocol.OpState) || v[1] != float64(2) || v[2] != float64(protocol.StatePlacingShips) {
		t.Fatalf("unexpected message: %v", v)
	}
}

func TestServerStateTransitions(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}
	// Initial state is StatePlacingShips
	if match.State() != StatePlacingShips {
		t.Fatalf("state = %d, want StatePlacingShips", match.State())
	}

	// Move to StatePlayer1Ready
	m.SetState(context.Background(), match, StatePlayer1Ready)
	p1Msgs, p2Msgs := c1.messages(), c2.messages()
	if v := parseMsg(t, p1Msgs[len(p1Msgs)-1]); v[2] != float64(protocol.StateWaitOpponentReady) {
		t.Fatalf("p1 got %v, want StateWaitOpponentReady (3)", v)
	}
	if v := parseMsg(t, p2Msgs[len(p2Msgs)-1]); v[2] != float64(protocol.StateOpponentReady) {
		t.Fatalf("p2 got %v, want StateOpponentReady (2)", v)
	}

	// Move to StatePlayer1Turn
	m.SetState(context.Background(), match, StatePlayer1Turn)
	p1Msgs, p2Msgs = c1.messages(), c2.messages()
	if v := parseMsg(t, p1Msgs[len(p1Msgs)-1]); v[2] != float64(protocol.StateYourTurn) {
		t.Fatalf("p1 got %v, want StateYourTurn (4)", v)
	}
	if v := parseMsg(t, p2Msgs[len(p2Msgs)-1]); v[2] != float64(protocol.StateWaitOpponentTurn) {
		t.Fatalf("p2 got %v, want StateWaitOpponentTurn (5)", v)
	}

	// Move to StatePlayer2Turn
	m.SetState(context.Background(), match, StatePlayer2Turn)
	p1Msgs, p2Msgs = c1.messages(), c2.messages()
	if v := parseMsg(t, p1Msgs[len(p1Msgs)-1]); v[2] != float64(protocol.StateWaitOpponentTurn) {
		t.Fatalf("p1 got %v, want StateWaitOpponentTurn (5)", v)
	}
	if v := parseMsg(t, p2Msgs[len(p2Msgs)-1]); v[2] != float64(protocol.StateYourTurn) {
		t.Fatalf("p2 got %v, want StateYourTurn (4)", v)
	}
}

func TestAckValidation(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}

	// seq <= 0 should fail
	if err := m.Ack(match, 0, 0); err != ErrInvalidSeq {
		t.Fatalf("ack 0: got err = %v, want ErrInvalidSeq", err)
	}
	if err := m.Ack(match, 0, -1); err != ErrInvalidSeq {
		t.Fatalf("ack -1: got err = %v, want ErrInvalidSeq", err)
	}

	// seq > slot.seq (e.g. 2 when only 1 sent) should fail
	if err := m.Ack(match, 0, 2); err != ErrInvalidSeq {
		t.Fatalf("ack 2: got err = %v, want ErrInvalidSeq", err)
	}

	// seq == 1 should succeed
	if err := m.Ack(match, 0, 1); err != nil {
		t.Fatalf("ack 1: unexpected err = %v", err)
	}

	// Idempotent duplicate ack should succeed
	if err := m.Ack(match, 0, 1); err != nil {
		t.Fatalf("repeat ack 1: unexpected err = %v", err)
	}
}

func TestEndMatchCleansUpMatch(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}

	// Match started successfully and is in m.matches
	if m.GetMatch(gc.MatchID) == nil {
		t.Fatal("expected match in m.matches")
	}

	// End match
	m.EndMatch(match.ID, 0, "game completed")

	// Match should be deleted from m.matches (preventing memory leak)
	if m.GetMatch(gc.MatchID) != nil {
		t.Fatal("expected match to be deleted from m.matches")
	}

	// Both connections should be notified and closed with CloseCodeNormal
	for i, c := range []*fakeConn{c1, c2} {
		msgs := c.messages()
		lastMsg := parseMsg(t, msgs[len(msgs)-1])
		if lastMsg[0] != float64(protocol.OpEnd) || lastMsg[3] != "game completed" {
			t.Fatalf("player %d unexpected END: %v", i, lastMsg)
		}
		if closed, code := c.isClosed(); !closed || code != protocol.CloseCodeNormal {
			t.Fatalf("player %d closed=%v code=%d, want closed with %d", i, closed, code, protocol.CloseCodeNormal)
		}
	}

	// Late join should replay END
	c3 := &fakeConn{}
	_, _, err = m.Join(context.Background(), c3, gc, gc.Player1ID)
	if err != ErrMatchFinished {
		t.Fatalf("err = %v, want ErrMatchFinished", err)
	}
	msgs := c3.messages()
	if len(msgs) != 1 {
		t.Fatalf("replayed %d messages, want 1", len(msgs))
	}
}

func TestManagerShutdown(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	_, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}

	m.Shutdown()

	for i, c := range []*fakeConn{c1, c2} {
		if closed, code := c.isClosed(); !closed || code != protocol.CloseCodeGoingAway {
			t.Fatalf("player %d closed=%v code=%d, want closed with %d", i, closed, code, protocol.CloseCodeGoingAway)
		}
	}
}

func TestJoinWhenMatchAlreadyEndedReplaysReason(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1 := &fakeConn{}

	_, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join: %v", err)
	}

	// Trigger onJoinTimeout so match is ended
	m.onJoinTimeout(gc.MatchID)

	// Late join on ended match must send the reason before closing
	c2 := &fakeConn{}
	_, _, err = m.Join(context.Background(), c2, gc, gc.Player2ID)
	if err != ErrMatchFinished {
		t.Fatalf("got err = %v, want ErrMatchFinished", err)
	}
	msgs := c2.messages()
	if len(msgs) != 1 {
		t.Fatalf("got %d messages, want 1", len(msgs))
	}
	v := parseMsg(t, msgs[0])
	if v[0] != float64(protocol.OpEnd) || v[2] != float64(protocol.EndCodeJoinTimeout) || v[3] != "join timeout exceeded" {
		t.Fatalf("unexpected message: %v", v)
	}
	if closed, code := c2.isClosed(); !closed || code != protocol.CloseCodeNormal {
		t.Fatalf("c2 closed=%v code=%d, want %d", closed, code, protocol.CloseCodeNormal)
	}
}

func mustMatch(t *testing.T, m *Manager, id string) *Match {
	t.Helper()
	m.mu.Lock()
	defer m.mu.Unlock()
	match, ok := m.matches[id]
	if !ok {
		t.Fatalf("match %q not found", id)
	}
	return match
}

func validTestShips() []protocol.Ship {
	return []protocol.Ship{
		// 4 size 1
		{Orientation: protocol.OrientationHorizontal, X: 9, Y: 4, Size: 1},
		{Orientation: protocol.OrientationVertical, X: 7, Y: 4, Size: 1},
		{Orientation: protocol.OrientationHorizontal, X: 5, Y: 4, Size: 1},
		{Orientation: protocol.OrientationHorizontal, X: 3, Y: 4, Size: 1},
		// 3 size 2
		{Orientation: protocol.OrientationHorizontal, X: 0, Y: 4, Size: 2},
		{Orientation: protocol.OrientationHorizontal, X: 7, Y: 2, Size: 2},
		{Orientation: protocol.OrientationHorizontal, X: 4, Y: 2, Size: 2},
		// 2 size 3
		{Orientation: protocol.OrientationHorizontal, X: 0, Y: 2, Size: 3},
		{Orientation: protocol.OrientationHorizontal, X: 5, Y: 0, Size: 3},
		// 1 size 4
		{Orientation: protocol.OrientationHorizontal, X: 0, Y: 0, Size: 4},
	}
}

func TestPlaceShipsP1First(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}
	if match.State() != StatePlacingShips {
		t.Fatalf("state = %d, want StatePlacingShips", match.State())
	}

	ships := validTestShips()

	// Player 1 places ships first
	if err := m.PlaceShips(context.Background(), match, 0, ships); err != nil {
		t.Fatalf("p1 place ships: %v", err)
	}
	if match.State() != StatePlayer1Ready {
		t.Fatalf("state = %d, want StatePlayer1Ready (2)", match.State())
	}

	// Verify stored ships and board for p1
	p1Ships := match.Ships(0)
	if len(p1Ships) != len(ships) {
		t.Fatalf("got %d ships, want %d", len(p1Ships), len(ships))
	}
	p1Board, placed := match.Board(0)
	if !placed {
		t.Fatal("expected p1 board placed to be true")
	}
	// Check that ship 9 (size 4 at 0,0 horizontal) is in p1 board with id 10
	for x := 0; x < 4; x++ {
		if p1Board[0][x] != 10 {
			t.Fatalf("p1Board[0][%d] = %d, want 10", x, p1Board[0][x])
		}
	}

	// Verify states delivered to p1 and p2
	p1Msgs, p2Msgs := c1.messages(), c2.messages()
	if v := parseMsg(t, p1Msgs[len(p1Msgs)-1]); v[2] != float64(protocol.StateWaitOpponentReady) {
		t.Fatalf("p1 got state %v, want StateWaitOpponentReady (3)", v)
	}
	if v := parseMsg(t, p2Msgs[len(p2Msgs)-1]); v[2] != float64(protocol.StateOpponentReady) {
		t.Fatalf("p2 got state %v, want StateOpponentReady (2)", v)
	}

	// Player 1 cannot place ships again
	if err := m.PlaceShips(context.Background(), match, 0, ships); err == nil {
		t.Fatal("expected error when player 1 places ships again")
	}

	// Player 2 places ships
	if err := m.PlaceShips(context.Background(), match, 1, ships); err != nil {
		t.Fatalf("p2 place ships: %v", err)
	}
	if match.State() != StatePlayer1Turn {
		t.Fatalf("state = %d, want StatePlayer1Turn (4)", match.State())
	}

	// Verify states delivered to p1 and p2 after game starts
	p1Msgs, p2Msgs = c1.messages(), c2.messages()
	if v := parseMsg(t, p1Msgs[len(p1Msgs)-1]); v[2] != float64(protocol.StateYourTurn) {
		t.Fatalf("p1 got state %v, want StateYourTurn (4)", v)
	}
	if v := parseMsg(t, p2Msgs[len(p2Msgs)-1]); v[2] != float64(protocol.StateWaitOpponentTurn) {
		t.Fatalf("p2 got state %v, want StateWaitOpponentTurn (5)", v)
	}

	// Subsequent PlaceShips calls are rejected
	if err := m.PlaceShips(context.Background(), match, 1, ships); err == nil {
		t.Fatal("expected error when match is in turn phase")
	}
}

func TestPlaceShipsP2First(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}

	ships := validTestShips()

	// Player 2 places ships first
	if err := m.PlaceShips(context.Background(), match, 1, ships); err != nil {
		t.Fatalf("p2 place ships: %v", err)
	}
	if match.State() != StatePlayer2Ready {
		t.Fatalf("state = %d, want StatePlayer2Ready (3)", match.State())
	}

	// Verify states delivered to p1 and p2
	p1Msgs, p2Msgs := c1.messages(), c2.messages()
	if v := parseMsg(t, p1Msgs[len(p1Msgs)-1]); v[2] != float64(protocol.StateOpponentReady) {
		t.Fatalf("p1 got state %v, want StateOpponentReady (2)", v)
	}
	if v := parseMsg(t, p2Msgs[len(p2Msgs)-1]); v[2] != float64(protocol.StateWaitOpponentReady) {
		t.Fatalf("p2 got state %v, want StateWaitOpponentReady (3)", v)
	}

	// Player 1 places ships
	if err := m.PlaceShips(context.Background(), match, 0, ships); err != nil {
		t.Fatalf("p1 place ships: %v", err)
	}
	if match.State() != StatePlayer2Turn {
		t.Fatalf("state = %d, want StatePlayer2Turn (5)", match.State())
	}

	// Player 2 finished first, so Player 2 gets first turn!
	p1Msgs, p2Msgs = c1.messages(), c2.messages()
	if v := parseMsg(t, p1Msgs[len(p1Msgs)-1]); v[2] != float64(protocol.StateWaitOpponentTurn) {
		t.Fatalf("p1 got state %v, want StateWaitOpponentTurn (5)", v)
	}
	if v := parseMsg(t, p2Msgs[len(p2Msgs)-1]); v[2] != float64(protocol.StateYourTurn) {
		t.Fatalf("p2 got state %v, want StateYourTurn (4)", v)
	}
}

func TestPlaceShipsValidationFailure(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}

	invalidShips := validTestShips()
	invalidShips[0].X = invalidShips[1].X // overlapping ships

	if err := m.PlaceShips(context.Background(), match, 0, invalidShips); err == nil {
		t.Fatal("expected validation error")
	}
	if match.State() != StatePlacingShips {
		t.Fatalf("state changed to %d on error, want StatePlacingShips", match.State())
	}
	if match.Ships(0) != nil {
		t.Fatal("expected nil ships for p1 after failed placement")
	}
}

func TestPlaceShipsBeforeMatchStarts(t *testing.T) {
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1 := &fakeConn{}

	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}

	if err := m.PlaceShips(context.Background(), match, 0, validTestShips()); err != ErrMatchNotStarted {
		t.Fatalf("got err = %v, want ErrMatchNotStarted", err)
	}
}

func setupStartedGame(t *testing.T) (*Manager, *Match, *fakeConn, *fakeConn) {
	t.Helper()
	m := NewManager(time.Minute)
	gc := claims(time.Now().Add(time.Hour))
	c1, c2 := &fakeConn{}, &fakeConn{}

	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
	if err != nil {
		t.Fatalf("join p1: %v", err)
	}
	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
		t.Fatalf("join p2: %v", err)
	}

	ships := validTestShips()
	if err := m.PlaceShips(context.Background(), match, 0, ships); err != nil {
		t.Fatalf("p1 place ships: %v", err)
	}
	if err := m.PlaceShips(context.Background(), match, 1, ships); err != nil {
		t.Fatalf("p2 place ships: %v", err)
	}
	if match.State() != StatePlayer1Turn {
		t.Fatalf("state = %d, want StatePlayer1Turn", match.State())
	}
	return m, match, c1, c2
}

func TestFireMissTransitionsTurn(t *testing.T) {
	m, match, c1, c2 := setupStartedGame(t)

	// In validTestShips, cell (9, 9) has no ships.
	res, err := m.Fire(context.Background(), match, 0, 9, 9)
	if err != nil {
		t.Fatalf("Fire: %v", err)
	}
	if res != protocol.FireResultMiss {
		t.Fatalf("res = %d, want FireResultMiss", res)
	}

	// Shooter receives FIRE_RESULT with miss (1)
	c1Msgs := c1.messages()
	// c1 got: [STATE 1], [STATE 3], [STATE 4], [FIRE_RESULT 1], [STATE 5]
	fireMsg := parseMsg(t, c1Msgs[len(c1Msgs)-2])
	if fireMsg[0] != float64(protocol.OpFireResult) || fireMsg[2] != float64(protocol.FireResultMiss) {
		t.Fatalf("unexpected fireMsg: %v", fireMsg)
	}

	// Turn transitions to Player 2
	if match.State() != StatePlayer2Turn {
		t.Fatalf("state = %d, want StatePlayer2Turn", match.State())
	}

	c1Last := parseMsg(t, c1Msgs[len(c1Msgs)-1])
	if c1Last[0] != float64(protocol.OpState) || c1Last[2] != float64(protocol.StateWaitOpponentTurn) {
		t.Fatalf("c1 last state = %v, want StateWaitOpponentTurn", c1Last)
	}

	c2Msgs := c2.messages()
	c2Last := parseMsg(t, c2Msgs[len(c2Msgs)-1])
	if c2Last[0] != float64(protocol.OpState) || c2Last[2] != float64(protocol.StateYourTurn) {
		t.Fatalf("c2 last state = %v, want StateYourTurn", c2Last)
	}

	// Target board cell (9, 9) marked struck
	struck, ok := match.Struck(1)
	if !ok || !struck[9][9] {
		t.Fatalf("expected p2 cell (9, 9) to be struck")
	}
}

func TestFireHitKeepsTurn(t *testing.T) {
	m, match, c1, c2 := setupStartedGame(t)

	// Ship 9 is 4 cells horizontally at (0, 0), (1, 0), (2, 0), (3, 0)
	res, err := m.Fire(context.Background(), match, 0, 0, 0)
	if err != nil {
		t.Fatalf("Fire: %v", err)
	}
	if res != protocol.FireResultHit {
		t.Fatalf("res = %d, want FireResultHit", res)
	}

	c1Msgs := c1.messages()
	fireMsg := parseMsg(t, c1Msgs[len(c1Msgs)-1])
	if fireMsg[0] != float64(protocol.OpFireResult) || fireMsg[2] != float64(protocol.FireResultHit) {
		t.Fatalf("unexpected fireMsg: %v", fireMsg)
	}

	// Turn stays with Player 1
	if match.State() != StatePlayer1Turn {
		t.Fatalf("state = %d, want StatePlayer1Turn", match.State())
	}

	// Player 2 should not have received any new messages
	c2Msgs := c2.messages()
	// c2 messages before: [STATE 1], [STATE 2], [STATE 5]
	if len(c2Msgs) != 3 {
		t.Fatalf("p2 received unexpected message: %d messages", len(c2Msgs))
	}
}

func TestFireSunkMarksSurroundings(t *testing.T) {
	m, match, c1, _ := setupStartedGame(t)

	// Ship 0 is 1 cell at (9, 4)
	res, err := m.Fire(context.Background(), match, 0, 9, 4)
	if err != nil {
		t.Fatalf("Fire: %v", err)
	}
	if res != protocol.FireResultSunk {
		t.Fatalf("res = %d, want FireResultSunk", res)
	}

	c1Msgs := c1.messages()
	fireMsg := parseMsg(t, c1Msgs[len(c1Msgs)-1])
	if fireMsg[0] != float64(protocol.OpFireResult) || fireMsg[2] != float64(protocol.FireResultSunk) {
		t.Fatalf("unexpected fireMsg: %v", fireMsg)
	}

	if match.ShipsRemaining(1) != 9 {
		t.Fatalf("shipsRemaining = %d, want 9", match.ShipsRemaining(1))
	}

	// Check that (9, 4) and surrounding cells (8,3), (8,4), (8,5), (9,3), (9,5) are struck
	struck, _ := match.Struck(1)
	expectedCells := [][2]int{
		{9, 4},
		{8, 3}, {8, 4}, {8, 5},
		{9, 3}, {9, 5},
	}
	for _, pt := range expectedCells {
		if !struck[pt[1]][pt[0]] {
			t.Fatalf("expected cell (%d, %d) to be struck", pt[0], pt[1])
		}
	}

	// Turn stays with Player 1 because hit/sunk does not pass turn unless game over
	if match.State() != StatePlayer1Turn {
		t.Fatalf("state = %d, want StatePlayer1Turn", match.State())
	}
}

func TestFireInvalidPosition(t *testing.T) {
	m, match, c1, _ := setupStartedGame(t)

	t.Run("out of bounds negative", func(t *testing.T) {
		res, err := m.Fire(context.Background(), match, 0, -1, 5)
		if err != nil {
			t.Fatalf("Fire: %v", err)
		}
		if res != protocol.FireResultInvalidPosition {
			t.Fatalf("res = %d, want FireResultInvalidPosition", res)
		}
		msgs := c1.messages()
		msg := parseMsg(t, msgs[len(msgs)-1])
		if msg[0] != float64(protocol.OpFireResult) || msg[2] != float64(protocol.FireResultInvalidPosition) {
			t.Fatalf("unexpected msg: %v", msg)
		}
	})

	t.Run("out of bounds over 9", func(t *testing.T) {
		res, err := m.Fire(context.Background(), match, 0, 10, 0)
		if err != nil {
			t.Fatalf("Fire: %v", err)
		}
		if res != protocol.FireResultInvalidPosition {
			t.Fatalf("res = %d, want FireResultInvalidPosition", res)
		}
	})

	t.Run("already struck cell", func(t *testing.T) {
		// First shoot (9, 4) - sinks single ship
		res, err := m.Fire(context.Background(), match, 0, 9, 4)
		if err != nil || res != protocol.FireResultSunk {
			t.Fatalf("initial fire: res=%d, err=%v", res, err)
		}

		// Shooting (9, 4) again returns InvalidPosition
		res, err = m.Fire(context.Background(), match, 0, 9, 4)
		if err != nil {
			t.Fatalf("repeat fire: %v", err)
		}
		if res != protocol.FireResultInvalidPosition {
			t.Fatalf("res = %d, want FireResultInvalidPosition", res)
		}

		// Shooting diagonal neighbor (8, 5) which was marked struck due to sunk ship also returns InvalidPosition
		res, err = m.Fire(context.Background(), match, 0, 8, 5)
		if err != nil {
			t.Fatalf("halo fire: %v", err)
		}
		if res != protocol.FireResultInvalidPosition {
			t.Fatalf("res = %d, want FireResultInvalidPosition", res)
		}
	})
}

func TestFireIgnoredWhenNotYourTurn(t *testing.T) {
	m, match, c1, c2 := setupStartedGame(t)

	// It's player 1's turn, player 2 tries to shoot
	c2CountBefore := len(c2.messages())
	res, err := m.Fire(context.Background(), match, 1, 0, 0)
	if err != ErrNotYourTurn {
		t.Fatalf("p2 fire: got err = %v, want ErrNotYourTurn", err)
	}
	if res != 0 {
		t.Fatalf("res = %d, want 0", res)
	}
	if len(c2.messages()) != c2CountBefore {
		t.Fatal("expected no messages sent to p2 on ignored fire")
	}

	// Match state unchanged
	if match.State() != StatePlayer1Turn {
		t.Fatalf("state = %d, want StatePlayer1Turn", match.State())
	}
	_ = c1
}

func TestFireWinCondition(t *testing.T) {
	m, match, c1, c2 := setupStartedGame(t)
	gc := claims(time.Now().Add(time.Hour))

	// Player 1 destroys all 10 ships of Player 2
	ships := validTestShips()
	for i, ship := range ships {
		cells := ship.Cells()
		for j, c := range cells {
			res, err := m.Fire(context.Background(), match, 0, c.X, c.Y)
			if err != nil {
				t.Fatalf("ship %d cell %d fire: %v", i, j, err)
			}
			if j < len(cells)-1 {
				if res != protocol.FireResultHit {
					t.Fatalf("ship %d cell %d: res = %d, want Hit", i, j, res)
				}
			} else {
				if res != protocol.FireResultSunk {
					t.Fatalf("ship %d cell %d: res = %d, want Sunk", i, j, res)
				}
			}
		}
	}

	// Match should be removed from m.matches (preventing memory leak)
	if m.GetMatch(match.ID) != nil {
		t.Fatal("expected match to be removed from m.matches")
	}

	// Check END messages sent to both players
	c1Msgs := c1.messages()
	// c1 receives FIRE_RESULT (sunk) followed by END (victory)
	c1End := parseMsg(t, c1Msgs[len(c1Msgs)-1])
	if c1End[0] != float64(protocol.OpEnd) || c1End[2] != float64(protocol.EndCodeVictory) || c1End[3] != "victory" {
		t.Fatalf("p1 got %v, want END with EndCodeVictory (1) 'victory'", c1End)
	}

	c2Msgs := c2.messages()
	c2End := parseMsg(t, c2Msgs[len(c2Msgs)-1])
	if c2End[0] != float64(protocol.OpEnd) || c2End[2] != float64(protocol.EndCodeDefeat) || c2End[3] != "defeat" {
		t.Fatalf("p2 got %v, want END with EndCodeDefeat (2) 'defeat'", c2End)
	}

	// Connections must be closed immediately with CloseCodeNormal
	if closed, code := c1.isClosed(); !closed || code != protocol.CloseCodeNormal {
		t.Fatalf("c1 closed=%v code=%d, want closed with %d", closed, code, protocol.CloseCodeNormal)
	}
	if closed, code := c2.isClosed(); !closed || code != protocol.CloseCodeNormal {
		t.Fatalf("c2 closed=%v code=%d, want closed with %d", closed, code, protocol.CloseCodeNormal)
	}

	// Late reconnects get the respective END messages replayed
	c1Rejoin := &fakeConn{}
	_, _, err := m.Join(context.Background(), c1Rejoin, gc, gc.Player1ID)
	if err != ErrMatchFinished {
		t.Fatalf("rejoin p1: got err = %v, want ErrMatchFinished", err)
	}
	msgs := c1Rejoin.messages()
	if len(msgs) != 1 {
		t.Fatalf("p1 got %d replay messages, want 1", len(msgs))
	}
	if v := parseMsg(t, msgs[0]); v[0] != float64(protocol.OpEnd) || v[2] != float64(protocol.EndCodeVictory) {
		t.Fatalf("p1 replayed msg = %v, want END victory", v)
	}

	c2Rejoin := &fakeConn{}
	_, _, err = m.Join(context.Background(), c2Rejoin, gc, gc.Player2ID)
	if err != ErrMatchFinished {
		t.Fatalf("rejoin p2: got err = %v, want ErrMatchFinished", err)
	}
	msgs = c2Rejoin.messages()
	if len(msgs) != 1 {
		t.Fatalf("p2 got %d replay messages, want 1", len(msgs))
	}
	if v := parseMsg(t, msgs[0]); v[0] != float64(protocol.OpEnd) || v[2] != float64(protocol.EndCodeDefeat) {
		t.Fatalf("p2 replayed msg = %v, want END defeat", v)
	}
}

func TestFireAckAndReplay(t *testing.T) {
	m, match, _, _ := setupStartedGame(t)

	// In setupStartedGame, c1 received 3 STATE messages (seq 1, 2, 3)
	// Player 1 fires: generates FIRE_RESULT with seq 4
	res, err := m.Fire(context.Background(), match, 0, 0, 0)
	if err != nil || res != protocol.FireResultHit {
		t.Fatalf("fire: res=%d, err=%v", res, err)
	}

	// Ack seq 4
	if err := m.Ack(match, 0, 4); err != nil {
		t.Fatalf("ack: %v", err)
	}

	// Player 1 fires again at (1, 0): generates FIRE_RESULT with seq 5
	res, err = m.Fire(context.Background(), match, 0, 1, 0)
	if err != nil || res != protocol.FireResultHit {
		t.Fatalf("fire 2: res=%d, err=%v", res, err)
	}

	// Reconnect player 1 without ACKing seq 5
	fresh := &fakeConn{}
	gc := claims(time.Now().Add(time.Hour))
	if _, _, err := m.Join(context.Background(), fresh, gc, gc.Player1ID); err != nil {
		t.Fatalf("rejoin: %v", err)
	}

	freshMsgs := fresh.messages()
	if len(freshMsgs) != 1 {
		t.Fatalf("rejoined player got %d messages, want 1", len(freshMsgs))
	}
	v := parseMsg(t, freshMsgs[0])
	// Should be replayed FIRE_RESULT [7, 5, 2]
	if v[0] != float64(protocol.OpFireResult) || v[1] != float64(5) || v[2] != float64(protocol.FireResultHit) {
		t.Fatalf("replayed msg = %v, want [7, 5, 2]", v)
	}
}