feat: add BookExceptionHandler

src/main/java/mate/academy/bookstore/config/I18nConfig.java

@@ -0,0 +1,27 @@
+package mate.academy.bookstore.config;
+
+import org.springframework.context.MessageSource;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.ReloadableResourceBundleMessageSource;
+import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
+
+@Configuration
+public class I18nConfig {
+    @Bean
+    public MessageSource messageSource() {
+        ReloadableResourceBundleMessageSource messageSource
+                = new ReloadableResourceBundleMessageSource();
+
+        messageSource.setBasename("classpath:messages");
+        messageSource.setDefaultEncoding("UTF-8");
+        return messageSource;
+    }
+
+    @Bean
+    public LocalValidatorFactoryBean getValidator() {
+        LocalValidatorFactoryBean bean = new LocalValidatorFactoryBean();
+        bean.setValidationMessageSource(messageSource());
+        return bean;
+    }
+}

src/main/java/mate/academy/bookstore/dto/BookRequestDto.java

@@ -8,17 +8,23 @@
 
 @Data
 public class BookRequestDto {
-    @NotBlank(message = "Title is required")
+    private static final String ISBN_PATTERN =
+            "^(?:ISBN(?:-1[03])?:? )?(?=[0-9X]{10}$|(?=(?:[0-9]+[- ]){3})"
+                + "[- 0-9X]{13}$|97[89][0-9]{10}$|(?=(?:[0-9]+[- ]){4})[- 0-9]{17}$)"
+                + "(?:97[89][- ]?)?[0-9]{1,5}[- ]?[0-9]+[- ]?[0-9]+[- ]?[0-9X]$";
+    private static final String PRICE_MIN = "0.01";
+
+    @NotBlank(message = "{validation.title.notempty}")
     private String title;
 
-    @NotBlank(message = "Author is required")
+    @NotBlank(message = "{validation.author.notempty}")
     private String author;
 
-    @NotBlank(message = "ISBN is required")
-    @Pattern(regexp = "^\\d{13}$", message = "The ISBN must contain exactly 13 digits")
+    @NotBlank(message = "{validation.isbn.notempty}")
+    @Pattern(regexp = ISBN_PATTERN, message = "{validation.isbn.valid}")
     private String isbn;
 
-    @DecimalMin(value = "0.01", message = "The price must be greater than 0")
+    @DecimalMin(value = PRICE_MIN, message = "{validation.price.valid}")
     private BigDecimal price;
 
     private String description;

src/main/java/mate/academy/bookstore/exception/EntityNotFoundException.java

@@ -1,9 +1,5 @@
 package mate.academy.bookstore.exception;
 
-import org.springframework.http.HttpStatus;
-import org.springframework.web.bind.annotation.ResponseStatus;
-
-@ResponseStatus(HttpStatus.NOT_FOUND)
 public class EntityNotFoundException extends RuntimeException {
     public EntityNotFoundException(String message) {
         super(message);

src/main/java/mate/academy/bookstore/handler/BookControllerExceptionHandler.java

@@ -0,0 +1,60 @@
+package mate.academy.bookstore.handler;
+
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import mate.academy.bookstore.exception.EntityNotFoundException;
+import org.springframework.dao.DataIntegrityViolationException;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.validation.FieldError;
+import org.springframework.validation.ObjectError;
+import org.springframework.web.bind.MethodArgumentNotValidException;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.ResponseBody;
+
+@ControllerAdvice
+public class BookControllerExceptionHandler {
+    @ExceptionHandler(EntityNotFoundException.class)
+    @ResponseBody
+    public ResponseEntity<Object> handleEntityNotFoundException(EntityNotFoundException ex) {
+        return getResponseEntity(HttpStatus.NOT_FOUND, ex.getMessage());
+    }
+
+    @ExceptionHandler(MethodArgumentNotValidException.class)
+    @ResponseBody
+    public ResponseEntity<Object> handleValidationExceptions(MethodArgumentNotValidException ex) {
+        Map<String, String> errors = new HashMap<>();
+        ex.getBindingResult().getAllErrors().forEach(error -> {
+            Map.Entry<String, String> errorMessage = getErrorMessage(error);
+            errors.put(errorMessage.getKey(), errorMessage.getValue());
+        });
+
+        return getResponseEntity(HttpStatus.BAD_REQUEST, errors);
+    }
+
+    @ExceptionHandler(DataIntegrityViolationException.class)
+    @ResponseBody
+    public ResponseEntity<Object> handleDataIntegrityViolationException(
+            DataIntegrityViolationException ex) {
+        return getResponseEntity(HttpStatus.CONFLICT, ex.getMessage());
+    }
+
+    private Map.Entry<String, String> getErrorMessage(ObjectError e) {
+        if (e instanceof FieldError fieldError) {
+            String field = fieldError.getField();
+            String message = e.getDefaultMessage();
+            return Map.entry(field, message);
+        }
+        return Map.entry("", e.getDefaultMessage());
+    }
+
+    private ResponseEntity<Object> getResponseEntity(HttpStatus status, Object errors) {
+        Map<String, Object> body = new LinkedHashMap<>();
+        body.put("success", status.is2xxSuccessful());
+        body.put("errors", errors);
+        return new ResponseEntity<>(body, status);
+    }
+}
+

src/main/java/mate/academy/bookstore/repository/BookRepository.java

@@ -1,7 +1,9 @@
 package mate.academy.bookstore.repository;
 
+import java.util.Optional;
 import mate.academy.bookstore.model.Book;
 import org.springframework.data.jpa.repository.JpaRepository;
 
 public interface BookRepository extends JpaRepository<Book, Long> {
+    Optional<Book> findByIsbn(String isbn);
 }

src/main/java/mate/academy/bookstore/service/impl/BookServiceImpl.java

@@ -9,6 +9,7 @@
 import mate.academy.bookstore.model.Book;
 import mate.academy.bookstore.repository.BookRepository;
 import mate.academy.bookstore.service.BookService;
+import org.springframework.dao.DataIntegrityViolationException;
 import org.springframework.stereotype.Service;
 
 @Service
@@ -19,6 +20,10 @@ public class BookServiceImpl implements BookService {
 
     @Override
     public BookDto save(BookRequestDto bookDto) {
+        bookRepository.findByIsbn(bookDto.getIsbn())
+                .ifPresent(s -> {
+                    throw new DataIntegrityViolationException("Book already exists.");
+                });
         Book book = bookMapper.toModel(bookDto);
         Book savedBook = bookRepository.save(book);
         return bookMapper.toDto(savedBook);

src/main/resources/messages.properties

@@ -0,0 +1,5 @@
+validation.title.notempty=Title is required
+validation.author.notempty=Author is required
+validation.isbn.notempty=The ISBN is required
+validation.isbn.valid=The ISBN is not valid
+validation.price.valid=The price must be greater than 0