more fancy features

README.md

@@ -55,11 +55,9 @@ err = cartService.ReserveForCart(ctx, inventory.CartReserveRequest{
 // Get available inventory (accounting for reservations)
 available, err := cartService.GetAvailableInventory(ctx, "item1", "warehouse1")
 
-// Get reservation status and remaining time
+// Get reservation summary for an item
-active, remaining, err := cartService.GetReservationStatus(ctx, "item1", "warehouse1", "cart123")
+summary, err := cartService.GetReservationSummary(ctx, "item1", "warehouse1")
-if active {
+fmt.Printf("Reservations: %d, Next release: %v, Remaining: %d\n", summary.ReservationCount, summary.EarliestRelease, summary.RemainingItems)
-    fmt.Printf("Reservation active, %v remaining\n", remaining)
-}
 ```
 
 ## Dependencies

pkg/inventory/redis_reservation_service.go

@@ -46,13 +46,13 @@ func totalReservedKey(sku SKU, locationID LocationID) string {
 
 func (s *RedisCartReservationService) ReserveForCart(ctx context.Context, req CartReserveRequest) error {
 	keys := []string{
-		getInventoryKey(req.Sku, req.LocationID),
+		getInventoryKey(req.SKU, req.LocationID),
-		cartQtyKey(req.Sku, req.LocationID),
+		cartQtyKey(req.SKU, req.LocationID),
-		cartExpKey(req.Sku, req.LocationID),
+		cartExpKey(req.SKU, req.LocationID),
-		totalReservedKey(req.Sku, req.LocationID),
+		totalReservedKey(req.SKU, req.LocationID),
 	}
 	args := []interface{}{
-		string(req.CartId),
+		string(req.CartID),
 		req.Quantity,
 		int64(req.TTL.Seconds()),
 	}
@@ -112,6 +112,39 @@ func (s *RedisCartReservationService) GetReservationStatus(ctx context.Context,
 	}, nil
 }
 
+func (s *RedisCartReservationService) GetReservationSummary(ctx context.Context, sku SKU, locationID LocationID) (*ReservationSummary, error) {
+	qtyKey := cartQtyKey(sku, locationID)
+	expKey := cartExpKey(sku, locationID)
+
+	// Get reservation count
+	reservationCount, err := s.client.HLen(ctx, qtyKey).Result()
+	if err != nil {
+		return nil, err
+	}
+
+	// Get earliest release (min score in sorted set)
+	minScore, err := s.client.ZRangeWithScores(ctx, expKey, 0, 0).Result()
+	if err != nil {
+		return nil, err
+	}
+	var earliestRelease time.Time
+	if len(minScore) > 0 {
+		earliestRelease = time.Unix(int64(minScore[0].Score), 0)
+	}
+
+	// Get remaining items
+	remainingItems, err := s.GetAvailableInventory(ctx, sku, locationID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &ReservationSummary{
+		ReservationCount: reservationCount,
+		EarliestRelease:  earliestRelease,
+		RemainingItems:   remainingItems,
+	}, nil
+}
+
 func (s *RedisCartReservationService) GetAvailableInventory(ctx context.Context, sku SKU, locationID LocationID) (int64, error) {
 	keys := []string{
 		getInventoryKey(sku, locationID),

pkg/inventory/redis_reservation_service_test.go

@@ -49,8 +49,8 @@ func TestReserveAndRelease(t *testing.T) {
 
 	// Reserve
 	req := CartReserveRequest{
-		InventoryReference: &InventoryReference{Sku: sku, LocationID: locationID},
+		InventoryReference: &InventoryReference{SKU: sku, LocationID: locationID},
-		CartId:             cartID,
+		CartID:             cartID,
 		Quantity:           2,
 		TTL:                5 * time.Minute,
 	}
@@ -132,8 +132,8 @@ func TestConcurrentReserves(t *testing.T) {
 		go func(cartNum int) {
 			defer wg.Done()
 			req := CartReserveRequest{
-				InventoryReference: &InventoryReference{Sku: sku, LocationID: locationID},
+				InventoryReference: &InventoryReference{SKU: sku, LocationID: locationID},
-				CartId:             CartID(fmt.Sprintf("cart%d", cartNum)),
+				CartID:             CartID(fmt.Sprintf("cart%d", cartNum)),
 				Quantity:           1,
 				TTL:                5 * time.Minute,
 			}
@@ -195,8 +195,8 @@ func TestExpiry(t *testing.T) {
 
 	// Reserve with short TTL
 	req := CartReserveRequest{
-		InventoryReference: &InventoryReference{Sku: sku, LocationID: locationID},
+		InventoryReference: &InventoryReference{SKU: sku, LocationID: locationID},
-		CartId:             cartID,
+		CartID:             cartID,
 		Quantity:           2,
 		TTL:                10 * time.Second,
 	}
@@ -239,3 +239,73 @@ func TestExpiry(t *testing.T) {
 		t.Errorf("expected available 8, got %d", available)
 	}
 }
+
+func TestGetReservationSummary(t *testing.T) {
+	client, mr, err := setupTestRedis()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer mr.Close()
+
+	service, err := NewRedisCartReservationService(client)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ctx := context.Background()
+	sku := SKU("test-item")
+	locationID := LocationID("warehouse1")
+
+	// Set initial inventory
+	err = client.Set(ctx, getInventoryKey(sku, locationID), 10, 0).Err()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Reserve two carts
+	req1 := CartReserveRequest{
+		InventoryReference: &InventoryReference{SKU: sku, LocationID: locationID},
+		CartID:             "cart1",
+		Quantity:           2,
+		TTL:                5 * time.Minute,
+	}
+	err = service.ReserveForCart(ctx, req1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	req2 := CartReserveRequest{
+		InventoryReference: &InventoryReference{SKU: sku, LocationID: locationID},
+		CartID:             "cart2",
+		Quantity:           1,
+		TTL:                10 * time.Minute,
+	}
+	err = service.ReserveForCart(ctx, req2)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Get summary
+	summary, err := service.GetReservationSummary(ctx, sku, locationID)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if summary.ReservationCount != 2 {
+		t.Errorf("expected 2 reservations, got %d", summary.ReservationCount)
+	}
+
+	if summary.RemainingItems != 7 {
+		t.Errorf("expected remaining 7, got %d", summary.RemainingItems)
+	}
+
+	if summary.EarliestRelease.IsZero() {
+		t.Error("expected earliest release time")
+	}
+
+	// Earliest should be cart1's expiry (5 min)
+	expectedEarliest := time.Now().Add(5 * time.Minute)
+	if summary.EarliestRelease.After(expectedEarliest.Add(1*time.Second)) || summary.EarliestRelease.Before(expectedEarliest.Add(-1*time.Second)) {
+		t.Errorf("earliest release time incorrect: %v", summary.EarliestRelease)
+	}
+}

pkg/inventory/redis_service.go

@@ -66,7 +66,7 @@ func (s *RedisInventoryService) GetInventoryBatch(ctx context.Context, refs ...*
 	pipe := s.client.Pipeline()
 	cmds := make([]*redis.StringCmd, len(refs))
 	for i, ref := range refs {
-		key := getInventoryKey(ref.Sku, ref.LocationID)
+		key := getInventoryKey(ref.SKU, ref.LocationID)
 		cmds[i] = pipe.Get(ctx, key)
 	}
 	_, err := pipe.Exec(ctx)
@@ -139,7 +139,7 @@ func makeKeysAndArgs(req ...ReserveRequest) ([]string, []string) {
 		if r.Quantity <= 0 {
 			return nil, nil
 		}
-		keys[i] = getInventoryKey(r.Sku, r.LocationID)
+		keys[i] = getInventoryKey(r.SKU, r.LocationID)
 		args[i] = strconv.Itoa(int(r.Quantity))
 	}
 	return keys, args

pkg/inventory/types.go

@@ -16,7 +16,7 @@ type InventoryItem struct {
 }
 
 type InventoryReference struct {
-	Sku        SKU
+	SKU        SKU
 	LocationID LocationID
 }
 
@@ -47,7 +47,7 @@ type CartID string
 
 type CartReserveRequest struct {
 	*InventoryReference
-	CartId   CartID
+	CartID   CartID
 	Quantity uint32
 	TTL      time.Duration
 }
@@ -58,9 +58,16 @@ type CartReservationService interface {
 	GetAvailableInventory(ctx context.Context, sku SKU, locationID LocationID) (int64, error)
 	GetReservationExpiry(ctx context.Context, sku SKU, locationID LocationID, cartID CartID) (time.Time, error)
 	GetReservationStatus(ctx context.Context, sku SKU, locationID LocationID, cartID CartID) (*ReservationStatus, error)
+	GetReservationSummary(ctx context.Context, sku SKU, locationID LocationID) (*ReservationSummary, error)
 }
 
 type ReservationStatus struct {
 	Active        bool
 	RemainingTime time.Duration
 }
+
+type ReservationSummary struct {
+	ReservationCount int64     `json:"reservation_count"`
+	EarliestRelease  time.Time `json:"earliest_release"`
+	RemainingItems   int64     `json:"remaining_items"`
+}