feat(product-gift): createMultiItem 单商品路径支持赠品（抽取 processGifts 共享方法）

cfc-backend/src/main/java/com/etotem/cfc/service/ProductOrderService.java

@@ -176,11 +176,6 @@ public class ProductOrderService {
             return Result.error("请先登录");
         }
 
-        if (dto.getItems() != null && !dto.getItems().isEmpty()
-                && dto.getGiftItemIds() != null && !dto.getGiftItemIds().isEmpty()) {
-            return Result.error("赠品仅支持单商品下单");
-        }
-
         if (dto.getItems() != null && !dto.getItems().isEmpty()) {
             return createMultiItem(dto, buyerId);
         }
@@ -266,44 +261,9 @@ public class ProductOrderService {
         order.setUpdatedAt(new Date());
         orderMapper.insert(order);
         // ===== 赠品校验与记录 =====
-        if (dto.getGiftItemIds() != null && !dto.getGiftItemIds().isEmpty()) {
-            MembershipLevelDTO currentLevel = order.getFamilyId() != null
-                    ? membershipService.getCurrentLevel(order.getFamilyId())
-                    : null;
-            String userLevel = currentLevel != null ? currentLevel.getLevelCode() : null;
-            if (userLevel == null || "FREE".equals(userLevel)) {
-                return Result.error("您暂无会员等级，无法享受赠品");
-            }
-            List<GiftConfigVO> activeConfigs = productGiftService.getActiveConfigsByProductAndLevel(
-                    product.getId(), userLevel);
-            if (activeConfigs.isEmpty()) {
-                return Result.error("您所在等级暂无该商品赠品");
-            }
-            Set<Long> allowedItemIds = activeConfigs.stream()
-                    .flatMap(c -> c.getItems().stream())
-                    .map(GiftConfigVO.GiftItemVO::getId)
-                    .collect(Collectors.toSet());
-            for (Long itemId : dto.getGiftItemIds()) {
-                if (!allowedItemIds.contains(itemId)) {
-                    return Result.error("赠品项不存在或超出权限");
-                }
-                ProductGiftItem giftItem = productGiftService.getActiveItemById(itemId);
-                if (giftItem == null) {
-                    return Result.error("赠品项不存在");
-                }
-                ProductOrderGift orderGift = new ProductOrderGift();
-                orderGift.setOrderId(order.getId());
-                orderGift.setOrderNo(order.getOrderNo());
-                orderGift.setGiftType(giftItem.getGiftType());
-                orderGift.setGiftProductId(giftItem.getGiftProductId());
-                orderGift.setGiftProductName(giftItem.getGiftProductName());
-                orderGift.setGiftProductImage(giftItem.getGiftProductImage());
-                orderGift.setCfValue(giftItem.getCfValue() != null ? giftItem.getCfValue() : 0);
-                orderGift.setQuantity(1);
-                orderGift.setFulfilled(0);
-                orderGift.setCreatedAt(new Date());
-                productOrderGiftMapper.insert(orderGift);
-            }
+        Result<Void> giftResult = processGifts(order, dto, product);
+        if (giftResult.getCode() != 200) {
+            return Result.error(giftResult.getMessage());
         }
         return Result.success(ProductOrderDTO.from(order));
     }
@@ -575,9 +535,69 @@ public class ProductOrderService {
         order.setCreatedAt(new Date());
         order.setUpdatedAt(new Date());
         orderMapper.insert(order);
+        // ===== 赠品校验与记录（仅单商品下单支持赠品） =====
+        if (dto.getGiftItemIds() != null && !dto.getGiftItemIds().isEmpty()) {
+            if (dto.getItems().size() > 1) {
+                return Result.error("赠品仅支持单商品下单");
+            }
+            Result<Void> giftResult = processGifts(order, dto, firstProduct);
+            if (giftResult.getCode() != 200) {
+                return Result.error(giftResult.getMessage());
+            }
+        }
         return Result.success(ProductOrderDTO.from(order));
     }
 
+    /**
+     * 赠品校验与记录：校验 giftItemIds 属于该商品该等级启用配置，写入 product_order_gifts（fulfilled=0）。
+     * 返回 code!=200 表示校验失败（调用方返回 Result.error(message)）。
+     */
+    private Result<Void> processGifts(ProductOrder order, CreateProductOrderDTO dto, Product product) {
+        if (dto.getGiftItemIds() == null || dto.getGiftItemIds().isEmpty()) {
+            return Result.success(null);
+        }
+        // 家庭创建者等级（MembershipService.getCurrentLevel 无会员时返回 FREE）
+        MembershipLevelDTO currentLevel = order.getFamilyId() != null
+                ? membershipService.getCurrentLevel(order.getFamilyId())
+                : null;
+        String userLevel = currentLevel != null ? currentLevel.getLevelCode() : null;
+        if (userLevel == null || "FREE".equals(userLevel)) {
+            return Result.error("您暂无会员等级，无法享受赠品");
+        }
+        // 查询该商品该等级下启用的赠品项（含库存校验）
+        List<GiftConfigVO> activeConfigs = productGiftService.getActiveConfigsByProductAndLevel(
+                product.getId(), userLevel);
+        if (activeConfigs.isEmpty()) {
+            return Result.error("您所在等级暂无该商品赠品");
+        }
+        Set<Long> allowedItemIds = activeConfigs.stream()
+                .flatMap(c -> c.getItems().stream())
+                .map(GiftConfigVO.GiftItemVO::getId)
+                .collect(Collectors.toSet());
+        for (Long itemId : dto.getGiftItemIds()) {
+            if (!allowedItemIds.contains(itemId)) {
+                return Result.error("赠品项不存在或超出权限");
+            }
+            ProductGiftItem giftItem = productGiftService.getActiveItemById(itemId);
+            if (giftItem == null) {
+                return Result.error("赠品项不存在");
+            }
+            ProductOrderGift orderGift = new ProductOrderGift();
+            orderGift.setOrderId(order.getId());
+            orderGift.setOrderNo(order.getOrderNo());
+            orderGift.setGiftType(giftItem.getGiftType());
+            orderGift.setGiftProductId(giftItem.getGiftProductId());
+            orderGift.setGiftProductName(giftItem.getGiftProductName());
+            orderGift.setGiftProductImage(giftItem.getGiftProductImage());
+            orderGift.setCfValue(giftItem.getCfValue() != null ? giftItem.getCfValue() : 0);
+            orderGift.setQuantity(1);
+            orderGift.setFulfilled(0);
+            orderGift.setCreatedAt(new Date());
+            productOrderGiftMapper.insert(orderGift);
+        }
+        return Result.success(null);
+    }
+
     public Result<Map<String, Object>> pay(String orderNo, Long userId) {
         ProductOrder order = orderMapper.selectOne(
             new LambdaQueryWrapper<ProductOrder>().eq(ProductOrder::getOrderNo, orderNo));