fix: Revise the base unit conversion section

Author: anh-tus

backend/src/main/java/com/smalltrend/dto/products/ProductVariantRespone.java

@@ -23,6 +23,7 @@ public class ProductVariantRespone {
     private String imageUrl;
     private Map<String, String> attributes;
     private Boolean isActive;
+    private Boolean isBaseUnit;
     private Boolean productActive;
     private BigDecimal taxRate;
     private String taxName;

backend/src/main/java/com/smalltrend/service/products/ProductVariantService.java

@@ -458,6 +458,22 @@ private ProductVariantRespone mapToResponse(ProductVariant variant) {
         response.setImageUrl(variant.getImageUrl());
         response.setSellPrice(variant.getSellPrice());
         response.setIsActive(variant.isActive());
+
+        boolean isConversionDerivedVariant = false;
+        if (product != null && product.getId() != null && variant.getUnit() != null && variant.getUnit().getId() != null) {
+            List<UnitConversion> conversionsToThisUnit = unitConversionRepository.findByProductIdAndToUnitId(
+                    product.getId(),
+                    variant.getUnit().getId());
+
+            isConversionDerivedVariant = conversionsToThisUnit.stream()
+                    .filter(conversion -> conversion != null
+                    && conversion.getVariant() != null
+                    && conversion.getVariant().getId() != null
+                    && !conversion.getVariant().getId().equals(variant.getId()))
+                    .anyMatch(conversion -> hasSameAttributes(conversion.getVariant(), variant));
+        }
+
+        response.setIsBaseUnit(!isConversionDerivedVariant);
         response.setProductActive(product != null ? product.getIsActive() : null);
         response.setAttributes(variant.getAttributes());
         response.setCreatedAt(variant.getCreatedAt());

backend/src/main/java/com/smalltrend/service/products/UnitConversionService.java

@@ -20,7 +20,9 @@
 
 import java.time.LocalDate;
 import java.math.RoundingMode;
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.stream.Collectors;
 
 @Service
@@ -58,6 +60,24 @@ public UnitConversionResponse addConversion(Integer variantId, UnitConversionReq
                 .orElseThrow(() -> new RuntimeException(
                 "Không tìm thấy biến thể với ID: " + variantId));
 
+        Integer productId = baseVariant.getProduct() != null ? baseVariant.getProduct().getId() : null;
+        Integer unitId = baseVariant.getUnit() != null ? baseVariant.getUnit().getId() : null;
+
+        if (productId != null && unitId != null) {
+            List<UnitConversion> conversionsToThisUnit = unitConversionRepository.findByProductIdAndToUnitId(productId, unitId);
+            boolean isConversionDerivedVariant = conversionsToThisUnit.stream()
+                    .filter(conversion -> conversion != null
+                    && conversion.getVariant() != null
+                    && conversion.getVariant().getId() != null
+                    && !conversion.getVariant().getId().equals(baseVariant.getId()))
+                    .anyMatch(conversion -> hasSameAttributes(conversion.getVariant(), baseVariant));
+
+            if (isConversionDerivedVariant) {
+                throw new RuntimeException("Chỉ biến thể đơn vị gốc mới được phép thêm quy đổi đơn vị.");
+            }
+        }
+
+
         Unit toUnit = unitRepository.findById(request.getToUnitId())
                 .orElseThrow(() -> new RuntimeException(
                 "Không tìm thấy đơn vị với ID: " + request.getToUnitId()));
@@ -94,7 +114,6 @@ public UnitConversionResponse addConversion(Integer variantId, UnitConversionReq
                 .unit(toUnit)
                 .sellPrice(request.getSellPrice())
                 .isActive(baseVariant.isActive())
-                .imageUrl(baseVariant.getImageUrl()) // Kế thừa ảnh từ variant gốc
                 .attributes(baseVariant.getAttributes() != null
                         ? new java.util.HashMap<>(baseVariant.getAttributes())
                         : new java.util.HashMap<>())
@@ -212,4 +231,10 @@ public UnitConversionResponse mapToResponse(UnitConversion entity) {
         response.setIsActive(entity.isActive());
         return response;
     }
+
+    private boolean hasSameAttributes(ProductVariant left, ProductVariant right) {
+        Map<String, String> leftAttrs = left != null && left.getAttributes() != null ? left.getAttributes() : Collections.emptyMap();
+        Map<String, String> rightAttrs = right != null && right.getAttributes() != null ? right.getAttributes() : Collections.emptyMap();
+        return leftAttrs.equals(rightAttrs);
+    }
 }

frontend/src/hooks/product_variants.js

@@ -27,6 +27,7 @@ export const useFetchVariants = (productId) => {
         stock_quantity: v.stockQuantity,
         image_url: v.imageUrl,
         is_active: v.isActive,
+        is_base_unit: v.isBaseUnit,
         created_at: v.createdAt,
         attributes: v.attributes,
         unit_conversions: v.unitConversions || [],

frontend/src/pages/Products/ProductManager/ProductDetail.jsx

@@ -680,15 +680,27 @@ function ProductDetail() {
                               >
                                 <Edit className="w-[18px] h-[18px]" />
                               </Button>
-                              <Button
-                                size="sm"
-                                variant="ghost"
-                                title={expandedVariantId === variant.id ? "Thu gọn quy đổi" : "Cấu hình quy đổi đơn vị"}
-                                onClick={() => setExpandedVariantId(expandedVariantId === variant.id ? null : variant.id)}
-                                className={`h-10 w-10 p-0 rounded-xl border border-gray-200 shadow-sm hover:shadow-md transition-all focus:ring-0 ${expandedVariantId === variant.id ? 'bg-indigo-100 text-indigo-700 border-indigo-200' : 'hover:bg-indigo-50 text-indigo-600'}`}
-                              >
-                                <Box className="w-[18px] h-[18px]" />
-                              </Button>
+                              {variant.is_base_unit ? (
+                                <Button
+                                  size="sm"
+                                  variant="ghost"
+                                  title={expandedVariantId === variant.id ? "Thu gọn quy đổi" : "Cấu hình quy đổi đơn vị"}
+                                  onClick={() => setExpandedVariantId(expandedVariantId === variant.id ? null : variant.id)}
+                                  className={`h-10 w-10 p-0 rounded-xl border border-gray-200 shadow-sm hover:shadow-md transition-all focus:ring-0 ${expandedVariantId === variant.id ? 'bg-indigo-100 text-indigo-700 border-indigo-200' : 'hover:bg-indigo-50 text-indigo-600'}`}
+                                >
+                                  <Box className="w-[18px] h-[18px]" />
+                                </Button>
+                              ) : (
+                                <Button
+                                  size="sm"
+                                  variant="ghost"
+                                  disabled
+                                  title="Biến thể quy đổi không được phép tạo thêm quy đổi"
+                                  className="h-10 w-10 p-0 rounded-xl border border-gray-200 text-gray-300 cursor-not-allowed bg-gray-50"
+                                >
+                                  <Box className="w-[18px] h-[18px]" />
+                                </Button>
+                              )}
                               {isWithin2Minutes(variant.created_at) && (
                                 <Button
                                   size="sm"
@@ -706,7 +718,7 @@ function ProductDetail() {
                       </TableCell>
                     </TableRow>
                     {/* Dòng hiển thị quy đổi đơn vị khi expand */}
-                    {canManageProduct && expandedVariantId === variant.id && (
+                    {canManageProduct && variant.is_base_unit && expandedVariantId === variant.id && (
                       <TableRow className="bg-gray-50/30">
                         <TableCell colSpan={10} className="p-0">
                           <div className="px-6 py-4 animate-in slide-in-from-top-2 duration-200 border-b border-gray-100">