Fix backend issues

backend/src/main/java/com/petshop/backend/controller/RefundController.java

@@ -30,7 +30,7 @@ public class RefundController {
     }
 
     @PostMapping
-    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF')")
     public ResponseEntity<RefundResponse> createRefund(@Valid @RequestBody RefundRequest request) {
         Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
         String role = authentication.getAuthorities().stream()
@@ -85,7 +85,7 @@ public class RefundController {
     }
 
     @PutMapping("/{id}")
-    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    @PreAuthorize("hasRole('STAFF')")
     public ResponseEntity<RefundResponse> updateRefund(@PathVariable Long id, @Valid @RequestBody RefundUpdateRequest request) {
         return ResponseEntity.ok(refundService.updateRefundStatus(id, request.getStatus()));
     }

backend/src/main/java/com/petshop/backend/controller/SaleController.java

@@ -40,7 +40,7 @@ public class SaleController {
     }
 
     @PostMapping
-    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    @PreAuthorize("hasRole('STAFF')")
     public ResponseEntity<SaleResponse> createSale(@Valid @RequestBody SaleRequest request) {
         return ResponseEntity.status(HttpStatus.CREATED).body(saleService.createSale(request));
     }

backend/src/main/java/com/petshop/backend/exception/GlobalExceptionHandler.java

@@ -42,9 +42,10 @@ public class GlobalExceptionHandler {
             errors.put(fieldName, errorMessage);
         });
 
+        String firstMessage = errors.values().stream().findFirst().orElse("Validation failed");
         Map<String, Object> response = new HashMap<>();
         response.put("status", HttpStatus.BAD_REQUEST.value());
-        response.put("message", "Validation failed");
+        response.put("message", firstMessage);
         response.put("errors", errors);
         response.put("details", buildDetails(ex));
         response.put("path", request.getRequestURI());

backend/src/main/java/com/petshop/backend/repository/ProductRepository.java

@@ -11,6 +11,10 @@ import org.springframework.stereotype.Repository;
 @Repository
 public interface ProductRepository extends JpaRepository<Product, Long> {
 
+    boolean existsByProdNameIgnoreCase(String prodName);
+
+    boolean existsByProdNameIgnoreCaseAndProdIdNot(String prodName, Long prodId);
+
     @Query("SELECT p FROM Product p WHERE " +
            "(:q IS NULL OR LOWER(p.prodName) LIKE LOWER(CONCAT('%', :q, '%')) OR LOWER(COALESCE(p.prodDesc, '')) LIKE LOWER(CONCAT('%', :q, '%'))) AND " +
            "(:categoryId IS NULL OR p.category.categoryId = :categoryId)")

backend/src/main/java/com/petshop/backend/service/ProductService.java

@@ -5,6 +5,7 @@ import com.petshop.backend.dto.product.ProductRequest;
 import com.petshop.backend.dto.product.ProductResponse;
 import com.petshop.backend.entity.Category;
 import com.petshop.backend.entity.Product;
+import com.petshop.backend.exception.BusinessException;
 import com.petshop.backend.exception.ResourceNotFoundException;
 import com.petshop.backend.repository.CategoryRepository;
 import com.petshop.backend.repository.ProductRepository;
@@ -45,6 +46,10 @@ public class ProductService {
 
     @Transactional
     public ProductResponse createProduct(ProductRequest request) {
+        if (productRepository.existsByProdNameIgnoreCase(request.getProdName())) {
+            throw new BusinessException("A product with this name already exists");
+        }
+
         Category category = categoryRepository.findById(request.getCategoryId())
                 .orElseThrow(() -> new ResourceNotFoundException("Category not found with id: " + request.getCategoryId()));
 
@@ -63,6 +68,10 @@ public class ProductService {
         Product product = productRepository.findById(id)
                 .orElseThrow(() -> new ResourceNotFoundException("Product not found with id: " + id));
 
+        if (productRepository.existsByProdNameIgnoreCaseAndProdIdNot(request.getProdName(), id)) {
+            throw new BusinessException("A product with this name already exists");
+        }
+
         Category category = categoryRepository.findById(request.getCategoryId())
                 .orElseThrow(() -> new ResourceNotFoundException("Category not found with id: " + request.getCategoryId()));
 

backend/src/main/resources/application.yml

@@ -68,6 +68,8 @@ openrouter:
   model: ${OPENROUTER_MODEL:openrouter/free}
 
 logging:
+  file:
+    name: ${LOG_FILE:log.txt}
   level:
     com.petshop: ${LOG_LEVEL:INFO}
     org.springframework.security: ${LOG_LEVEL_SECURITY:WARN}