v0.6.0 multi-user game support with longpoll, tests and doc updated

internal/service/game.go

@@ -104,6 +104,9 @@ func (s *Service) ApplyMove(gameID, moveUCI, newFEN string) error {
 	// Add the new position to game history
 	g.AddSnapshot(newFEN, moveUCI, nextTurn)
 
+	// Notify waiting clients about the state change
+	s.waiter.NotifyGame(gameID, len(g.Moves()))
+
 	// Persist if storage enabled
 	if s.store != nil {
 		moveNumber := len(g.Moves())
@@ -132,6 +135,12 @@ func (s *Service) UpdateGameState(gameID string, state core.State) error {
 	}
 
 	g.SetState(state)
+
+	// Notify if game ended
+	if state != core.StateOngoing && state != core.StatePending {
+		s.waiter.NotifyGame(gameID, len(g.Moves()))
+	}
+
 	return nil
 }
 
@@ -165,6 +174,9 @@ func (s *Service) UndoMoves(gameID string, count int) error {
 		return err
 	}
 
+	// Notify waiting clients about the undo
+	s.waiter.NotifyGame(gameID, len(g.Moves()))
+
 	// Delete undone moves from storage if enabled
 	if s.store != nil {
 		remainingMoves := originalMoveCount - count
@@ -183,6 +195,9 @@ func (s *Service) DeleteGame(gameID string) error {
 		return fmt.Errorf("game not found: %s", gameID)
 	}
 
+	// Notify and remove all waiters before deletion
+	s.waiter.RemoveGame(gameID)
+
 	delete(s.games, gameID)
 	return nil
 }

internal/service/service.go

@@ -2,7 +2,11 @@
 package service
 
 import (
+	"context"
+	"errors"
+	"fmt"
 	"sync"
+	"time"
 
 	"chess/internal/game"
 	"chess/internal/storage"
@@ -14,15 +18,17 @@ type Service struct {
 	mu        sync.RWMutex
 	store     *storage.Store // nil if persistence disabled
 	jwtSecret []byte
+	waiter    *WaitRegistry // Long-polling notification registry
 }
 
 // New creates a new service instance with optional storage
-func New(store *storage.Store, jwtSecret []byte) (*Service, error) {
+func New(store *storage.Store, jwtSecret []byte) *Service {
 	return &Service{
 		games:     make(map[string]*game.Game),
 		store:     store,
 		jwtSecret: jwtSecret,
-	}, nil
+		waiter:    NewWaitRegistry(),
+	}
 }
 
 // GetStorageHealth returns the storage component status
@@ -36,8 +42,21 @@ func (s *Service) GetStorageHealth() string {
 	return "degraded"
 }
 
-// Close cleans up resources
-func (s *Service) Close() error {
+// RegisterWait registers a client to wait for game state changes
+func (s *Service) RegisterWait(gameID string, moveCount int, ctx context.Context) <-chan struct{} {
+	return s.waiter.RegisterWait(gameID, moveCount, ctx)
+}
+
+// Shutdown gracefully shuts down the service
+func (s *Service) Shutdown(timeout time.Duration) error {
+	// Collect all errors
+	var errs []error
+
+	// Shutdown wait registry
+	if err := s.waiter.Shutdown(timeout); err != nil {
+		errs = append(errs, fmt.Errorf("wait registry: %w", err))
+	}
+
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
@@ -46,8 +65,10 @@ func (s *Service) Close() error {
 
 	// Close storage if enabled
 	if s.store != nil {
-		return s.store.Close()
+		if err := s.store.Close(); err != nil {
+			errs = append(errs, fmt.Errorf("storage: %w", err))
+		}
 	}
 
-	return nil
+	return errors.Join(errs...)
 }

internal/service/waiter.go

@@ -0,0 +1,178 @@
+// FILE: internal/service/waiter.go
+package service
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+)
+
+const (
+	// WaitTimeout is the maximum time a client can wait for notifications
+	WaitTimeout = 25 * time.Second
+
+	// WaitChannelBuffer size for notification channels
+	WaitChannelBuffer = 1
+)
+
+// WaitRegistry manages long-polling clients waiting for game state changes
+type WaitRegistry struct {
+	mu       sync.RWMutex
+	waiters  map[string][]*WaitRequest // gameID → waiting clients
+	shutdown chan struct{}
+	wg       sync.WaitGroup
+}
+
+// WaitRequest represents a single client waiting for game updates
+type WaitRequest struct {
+	MoveCount int             // Last known move count
+	Notify    chan struct{}   // Buffered channel for notifications
+	Timer     *time.Timer     // Timeout timer
+	Context   context.Context // Client connection context
+	GameID    string          // Game being watched
+}
+
+// NewWaitRegistry creates a new wait registry
+func NewWaitRegistry() *WaitRegistry {
+	return &WaitRegistry{
+		waiters:  make(map[string][]*WaitRequest),
+		shutdown: make(chan struct{}),
+	}
+}
+
+// RegisterWait registers a client to wait for game state changes
+func (w *WaitRegistry) RegisterWait(gameID string, moveCount int, ctx context.Context) <-chan struct{} {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	// Create wait request
+	req := &WaitRequest{
+		MoveCount: moveCount,
+		Notify:    make(chan struct{}, WaitChannelBuffer),
+		Context:   ctx,
+		GameID:    gameID,
+	}
+
+	// Setup timeout timer
+	req.Timer = time.AfterFunc(WaitTimeout, func() {
+		w.handleTimeout(req)
+	})
+
+	// Add to waiters map
+	w.waiters[gameID] = append(w.waiters[gameID], req)
+
+	// Setup cleanup on context cancellation
+	w.wg.Add(1)
+	go func() {
+		defer w.wg.Done()
+		select {
+		case <-ctx.Done():
+			// Client disconnected
+			w.removeWaiter(gameID, req)
+		case <-req.Notify:
+			// Notification received
+			req.Timer.Stop()
+			w.removeWaiter(gameID, req)
+		case <-w.shutdown:
+			// Server shutting down
+			req.Timer.Stop()
+			close(req.Notify)
+		}
+	}()
+
+	return req.Notify
+}
+
+// NotifyGame notifies all clients waiting on a game about state change
+func (w *WaitRegistry) NotifyGame(gameID string, currentMoveCount int) {
+	w.mu.RLock()
+	waitList := w.waiters[gameID]
+	w.mu.RUnlock()
+
+	if len(waitList) == 0 {
+		return
+	}
+
+	// Non-blocking notification to all waiters
+	for _, req := range waitList {
+		// Only notify if move count changed
+		if req.MoveCount != currentMoveCount {
+			select {
+			case req.Notify <- struct{}{}:
+				// Notification sent
+			default:
+				// Channel full or closed, skip slow client
+			}
+		}
+	}
+}
+
+// RemoveGame removes all waiters for a game (called before game deletion)
+func (w *WaitRegistry) RemoveGame(gameID string) {
+	w.mu.Lock()
+	waitList := w.waiters[gameID]
+	delete(w.waiters, gameID)
+	w.mu.Unlock()
+
+	// Notify all waiters that game is gone
+	for _, req := range waitList {
+		select {
+		case req.Notify <- struct{}{}:
+		default:
+		}
+	}
+}
+
+// Shutdown gracefully shuts down the wait registry
+func (w *WaitRegistry) Shutdown(timeout time.Duration) error {
+	close(w.shutdown)
+
+	// Wait for all goroutines with timeout
+	done := make(chan struct{})
+	go func() {
+		w.wg.Wait()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		return nil
+	case <-time.After(timeout):
+		return fmt.Errorf("http wait registry shutdown failed")
+	}
+}
+
+// handleTimeout handles wait request timeout
+func (w *WaitRegistry) handleTimeout(req *WaitRequest) {
+	// Send timeout notification
+	select {
+	case req.Notify <- struct{}{}:
+		// Timeout notification sent
+	default:
+		// Channel full or closed
+	}
+}
+
+// removeWaiter removes a specific waiter from the registry
+func (w *WaitRegistry) removeWaiter(gameID string, req *WaitRequest) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	waitList := w.waiters[gameID]
+	for i, waiter := range waitList {
+		if waiter == req {
+			// Remove from slice
+			w.waiters[gameID] = append(waitList[:i], waitList[i+1:]...)
+			break
+		}
+	}
+
+	// Clean up empty entries
+	if len(w.waiters[gameID]) == 0 {
+		delete(w.waiters, gameID)
+	}
+
+	// Stop timer if still running
+	req.Timer.Stop()
+}