completed exception handlers

orders-backend/src/main/java/com/andwati/orders/exception/GlobalExceptionHandler.java

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+package com.andwati.orders.exception;
+
+import com.andwati.orders.dto.response.ErrorResponse;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.validation.ConstraintViolationException;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.validation.FieldError;
+import org.springframework.web.bind.MethodArgumentNotValidException;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+import org.springframework.web.method.annotation.HandlerMethodValidationException;
+
+import java.time.Instant;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@RestControllerAdvice
+public class GlobalExceptionHandler {
+
+    @ExceptionHandler(MethodArgumentNotValidException.class)
+    public ResponseEntity<ErrorResponse> handleMethodArgumentNotValid(
+            MethodArgumentNotValidException exception,
+            HttpServletRequest request
+    ) {
+        List<Map<String, String>> details = exception.getBindingResult()
+                .getFieldErrors()
+                .stream()
+                .map(this::fieldErrorToMap)
+                .toList();
+
+        return build(
+                HttpStatus.BAD_REQUEST,
+                "VALIDATION_ERROR",
+                "Request validation failed",
+                details,
+                request
+        );
+    }
+
+    @ExceptionHandler(ConstraintViolationException.class)
+    public ResponseEntity<ErrorResponse> handleConstraintViolation(
+            ConstraintViolationException exception,
+            HttpServletRequest request
+    ) {
+        List<Map<String, String>> details = exception.getConstraintViolations()
+                .stream()
+                .map(violation -> Map.of(
+                        "field", violation.getPropertyPath().toString(),
+                        "message", violation.getMessage()
+                ))
+                .toList();
+
+        return build(
+                HttpStatus.BAD_REQUEST,
+                "VALIDATION_ERROR",
+                "Request validation failed",
+                details,
+                request
+        );
+    }
+
+    @ExceptionHandler(HandlerMethodValidationException.class)
+    public ResponseEntity<ErrorResponse> handleHandlerMethodValidation(
+            HandlerMethodValidationException exception,
+            HttpServletRequest request
+    ) {
+        return build(
+                HttpStatus.BAD_REQUEST,
+                "VALIDATION_ERROR",
+                "Request validation failed",
+                exception.getMessage(),
+                request
+        );
+    }
+
+    @ExceptionHandler(ProductNotFoundException.class)
+    public ResponseEntity<ErrorResponse> handleProductNotFound(
+            ProductNotFoundException exception,
+            HttpServletRequest request
+    ) {
+        return build(
+                HttpStatus.NOT_FOUND,
+                "PRODUCT_NOT_FOUND",
+                exception.getMessage(),
+                null,
+                request
+        );
+    }
+
+    @ExceptionHandler(OrderNotFoundException.class)
+    public ResponseEntity<ErrorResponse> handleOrderNotFound(
+            OrderNotFoundException exception,
+            HttpServletRequest request
+    ) {
+        return build(
+                HttpStatus.NOT_FOUND,
+                "ORDER_NOT_FOUND",
+                exception.getMessage(),
+                null,
+                request
+        );
+    }
+
+    @ExceptionHandler(InventoryNotFoundException.class)
+    public ResponseEntity<ErrorResponse> handleInventoryNotFound(
+            InventoryNotFoundException exception,
+            HttpServletRequest request
+    ) {
+        return build(
+                HttpStatus.NOT_FOUND,
+                "INVENTORY_NOT_FOUND",
+                exception.getMessage(),
+                null,
+                request
+        );
+    }
+
+    @ExceptionHandler(InsufficientStockException.class)
+    public ResponseEntity<ErrorResponse> handleInsufficientStock(
+            InsufficientStockException exception,
+            HttpServletRequest request
+    ) {
+        return build(
+                HttpStatus.CONFLICT,
+                "INSUFFICIENT_STOCK",
+                exception.getMessage(),
+                exception.getDetails(),
+                request
+        );
+    }
+
+    @ExceptionHandler(OrderNotCancellableException.class)
+    public ResponseEntity<ErrorResponse> handleOrderNotCancellable(
+            OrderNotCancellableException exception,
+            HttpServletRequest request
+    ) {
+        return build(
+                HttpStatus.CONFLICT,
+                "ORDER_NOT_CANCELLABLE",
+                exception.getMessage(),
+                null,
+                request
+        );
+    }
+
+    @ExceptionHandler(IllegalArgumentException.class)
+    public ResponseEntity<ErrorResponse> handleIllegalArgument(
+            IllegalArgumentException exception,
+            HttpServletRequest request
+    ) {
+        return build(
+                HttpStatus.BAD_REQUEST,
+                "VALIDATION_ERROR",
+                exception.getMessage(),
+                null,
+                request
+        );
+    }
+
+    @ExceptionHandler(Exception.class)
+    public ResponseEntity<ErrorResponse> handleUnexpected(
+            Exception exception,
+            HttpServletRequest request
+    ) {
+        return build(
+                HttpStatus.INTERNAL_SERVER_ERROR,
+                "INTERNAL_ERROR",
+                "An unexpected error occurred",
+                null,
+                request
+        );
+    }
+
+    private Map<String, String> fieldErrorToMap(FieldError fieldError) {
+        Map<String, String> map = new HashMap<>();
+        map.put("field", fieldError.getField());
+        map.put("message", fieldError.getDefaultMessage());
+        return map;
+    }
+
+    private ResponseEntity<ErrorResponse> build(
+            HttpStatus status,
+            String error,
+            String message,
+            Object details,
+            HttpServletRequest request
+    ) {
+        ErrorResponse response = new ErrorResponse(
+                error,
+                message,
+                details,
+                Instant.now(),
+                request.getRequestURI()
+        );
+
+        return ResponseEntity.status(status).body(response);
+    }
+}

orders-backend/src/main/java/com/andwati/orders/exception/InsufficientStockException.java

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+package com.andwati.orders.exception;
+
+import java.util.Map;
+import java.util.UUID;
+
+public class InsufficientStockException extends RuntimeException {
+
+    private final Map<String, Object> details;
+
+    public InsufficientStockException(
+            UUID productId,
+            String productName,
+            int requestedQuantity,
+            int availableQuantity
+    ) {
+        super("Insufficient stock for " + productName);
+        this.details = Map.of(
+                "productId", productId,
+                "productName", productName,
+                "requestedQuantity", requestedQuantity,
+                "availableQuantity", availableQuantity
+        );
+    }
+
+    public Map<String, Object> getDetails() {
+        return details;
+    }
+}

orders-backend/src/main/java/com/andwati/orders/exception/InventoryNotFoundException.java

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+package com.andwati.orders.exception;
+
+import java.util.UUID;
+
+public class InventoryNotFoundException extends RuntimeException {
+
+    public InventoryNotFoundException(UUID productId) {
+        super("Inventory record for product " + productId + " does not exist");
+    }
+}

orders-backend/src/main/java/com/andwati/orders/exception/OrderNotCancellableException.java

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+package com.andwati.orders.exception;
+
+import java.util.UUID;
+
+public class OrderNotCancellableException extends RuntimeException {
+
+    public OrderNotCancellableException(UUID orderId) {
+        super("Order " + orderId + " cannot be cancelled because it is not in PLACED status");
+    }
+}

orders-backend/src/main/java/com/andwati/orders/exception/OrderNotFoundException.java

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+package com.andwati.orders.exception;
+
+import java.util.UUID;
+
+public class OrderNotFoundException extends RuntimeException {
+
+    public OrderNotFoundException(UUID orderId) {
+        super("Order " + orderId + " does not exist");
+    }
+}

orders-backend/src/main/java/com/andwati/orders/exception/ProductNotFoundException.java

@@ -0,0 +1,10 @@
+package com.andwati.orders.exception;
+
+import java.util.UUID;
+
+public class ProductNotFoundException extends RuntimeException {
+
+    public ProductNotFoundException(UUID productId) {
+        super("Product " + productId + " does not exist");
+    }
+}