[STUD-69] Exception raising and returns

src/main/java/com/studai/config/CorsConfig.java

@@ -12,7 +12,7 @@ public void addCorsMappings(CorsRegistry registry) {
         registry.addMapping("/api/**")
                 .allowedOriginPatterns("*")
                 .allowedMethods("GET", "POST", "PUT", "DELETE", "OPTIONS")
-                .allowedHeaders("*")
+                .allowedHeaders("Authorization", "Content-Type")
                 .allowCredentials(true)
                 .maxAge(3600);
     }

src/main/java/com/studai/domain/quiz/Quiz.java

@@ -5,6 +5,8 @@
 import jakarta.persistence.*;
 import lombok.*;
 import com.studai.domain.question.Question;
+
+import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
 
@@ -44,6 +46,6 @@ public class Quiz {
 
     @OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, orphanRemoval = true)
     @JoinColumn(name = "quiz_id")
-    private List<QuizAttempt> attempts;
+    private List<QuizAttempt> attempts = new ArrayList<>();
 
 }

src/main/java/com/studai/domain/quiz/dto/QuizDTO.java

@@ -7,6 +7,7 @@
 import jakarta.persistence.Column;
 import lombok.*;
 
+import java.util.ArrayList;
 import java.util.List;
 
 @Getter
@@ -24,6 +25,6 @@ public class QuizDTO {
     private QuizSourceType sourceType;
     private String sourceUri;
     private String userId;
-    private List<QuizAttemptDTO> attempts;
+    private List<QuizAttemptDTO> attempts = new ArrayList<>();
 
 }

src/main/java/com/studai/service/question/QuestionService.java

@@ -22,26 +22,26 @@ public class QuestionService {
     private QuizRepository quizRepository;
 
     public QuestionDTO create(QuestionDTO dto){
-        Quiz quiz = quizRepository.findById(UUID.fromString(dto.getQuizId())).orElseThrow(ResourceNotFoundException::new);
+        Quiz quiz = quizRepository.findById(UUID.fromString(dto.getQuizId())).orElseThrow(() -> new ResourceNotFoundException("Quiz not found with ID: " + dto.getQuizId()));
         Question entity = questionRepository.save(QuestionAssembler.toEntity(dto, quiz));
         return QuestionAssembler.toDTO(entity);
     }
 
     public QuestionDTO findById(String id){
-        Question entity = questionRepository.findById(UUID.fromString(id)).orElseThrow(ResourceNotFoundException::new);
+        Question entity = questionRepository.findById(UUID.fromString(id)).orElseThrow(() -> new ResourceNotFoundException("Question not found with ID: " + id));
         return QuestionAssembler.toDTO(entity);
     }
 
     public QuestionDTO update(QuestionDTO questionDTO) {
-        Question existingQuestion = questionRepository.findById(UUID.fromString(questionDTO.getId())).orElseThrow(ResourceNotFoundException::new);
+        Question existingQuestion = questionRepository.findById(UUID.fromString(questionDTO.getId())).orElseThrow(() -> new ResourceNotFoundException("Question not found with ID: " + questionDTO.getId()));
         Question updatedQuestion = QuestionAssembler.toEntity(questionDTO, existingQuestion.getQuiz());
         updatedQuestion.setId(existingQuestion.getId());
 
         return QuestionAssembler.toDTO(questionRepository.save(updatedQuestion));
     }
 
     public QuestionDTO delete(String id) {
-        Question entity = questionRepository.findById(UUID.fromString(id)).orElseThrow(ResourceNotFoundException::new);
+        Question entity = questionRepository.findById(UUID.fromString(id)).orElseThrow(() -> new ResourceNotFoundException("Question not found with ID: " + id));
         questionRepository.delete(entity);
         return QuestionAssembler.toDTO(entity);
     }

src/main/java/com/studai/service/quiz/QuizService.java

@@ -59,14 +59,15 @@ public QuizDTO create(String videoId, int questionsNumber, String language){
         return QuizAssembler.toDTO(entity);
     }
 
-    public QuizDTO findById(String id){
-        Quiz quiz = quizRepository.findById(UUID.fromString(id)).orElseThrow(ResourceNotFoundException::new);
+    public QuizDTO findById(String id) {
+        Quiz quiz = quizRepository.findById(UUID.fromString(id))
+                .orElseThrow(() -> new ResourceNotFoundException("Quiz not found with ID: " + id));
         return QuizAssembler.toDTO(quiz);
     }
 
+
     public List<QuizDTO> findAll() {
         List<Quiz> quizzes = quizRepository.findByUser(userService.getCurrentUser());
-        if(quizzes.isEmpty()) throw new ResourceNotFoundException();
         List<QuizDTO> quizDtos = new ArrayList<>();
         for(Quiz quiz : quizzes){
             quizDtos.add(QuizAssembler.toDTO(quiz));
@@ -76,7 +77,7 @@ public List<QuizDTO> findAll() {
 
     public QuizDTO update(QuizDTO quizDTO) {
         Quiz quiz = quizRepository.findById(UUID.fromString(quizDTO.getId()))
-            .orElseThrow(ResourceNotFoundException::new);
+            .orElseThrow(() -> new ResourceNotFoundException("Quiz not found with ID: " + quizDTO.getId()));
 
         quiz.setTitle(quizDTO.getTitle());
         quiz.setDescription(quizDTO.getDescription());
@@ -112,14 +113,14 @@ public QuizDTO update(QuizDTO quizDTO) {
 
 
     public QuizDTO delete(String id) {
-        Quiz quiz = quizRepository.findById(UUID.fromString(id)).orElseThrow(ResourceNotFoundException::new);
+        Quiz quiz = quizRepository.findById(UUID.fromString(id)).orElseThrow(() -> new ResourceNotFoundException("Quiz not found with ID: " + id));
         quizRepository.delete(quiz);
         return QuizAssembler.toDTO(quiz);
     }
 
     public QuizAttemptDTO submitAttempt(String quizId, Double score, Long timeSpent){
         QuizAttempt attempt = QuizAttempt.builder()
-            .quiz(quizRepository.findById(UUID.fromString(quizId)).orElseThrow(ResourceNotFoundException::new))
+            .quiz(quizRepository.findById(UUID.fromString(quizId)).orElseThrow(() -> new ResourceNotFoundException("Quiz not found with ID: " + quizId)))
             .user(userService.getCurrentUser())
             .score(score)
             .timeSpent(timeSpent)

src/main/java/com/studai/utils/assembler/QuestionAssembler.java

@@ -3,7 +3,9 @@
 import com.studai.domain.question.Question;
 import com.studai.domain.question.dto.QuestionDTO;
 import com.studai.domain.quiz.Quiz;
+import com.studai.domain.quiz.attempt.QuizAttempt;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
 import java.util.stream.Collectors;
@@ -38,14 +40,14 @@ public static QuestionDTO toDTO(Question question) {
     }
 
     public static List<Question> toEntityList(List<QuestionDTO> dtoList, Quiz quiz) {
-        if(dtoList == null) return null;
+        if(dtoList == null) return new ArrayList<>();
         return dtoList.stream()
             .map(dto -> toEntity(dto, quiz))
             .collect(Collectors.toList());
     }
 
     public static List<QuestionDTO> toDTOList(List<Question> questions) {
-        if(questions == null) return null;
+        if(questions == null) return new ArrayList<>();
         return questions.stream()
             .map(QuestionAssembler::toDTO)
             .collect(Collectors.toList());

src/main/java/com/studai/utils/assembler/QuizAssembler.java

@@ -28,6 +28,7 @@ public static Quiz toEntity(QuizDTO dto, User user){
         quiz.setQuestions(questions);
 
         List<QuizAttempt> attempts = QuizAttemptAssembler.toEntityList(dto.getAttempts(), quiz, user);
+        quiz.setAttempts(attempts);
 
         return quiz;
     }

src/main/java/com/studai/utils/assembler/QuizAttemptAssembler.java

@@ -5,6 +5,7 @@
 import com.studai.domain.quiz.Quiz;
 import com.studai.domain.user.User;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
 import java.util.stream.Collectors;
@@ -34,14 +35,14 @@ public static QuizAttemptDTO toDTO(QuizAttempt quizAttempt) {
     }
 
     public static List<QuizAttempt> toEntityList(List<QuizAttemptDTO> dtoList, Quiz quiz, User user) {
-        if(dtoList == null || dtoList.isEmpty()) return null;
+        if(dtoList == null || dtoList.isEmpty()) return new ArrayList<>();
         return dtoList.stream()
             .map(dto -> toEntity(dto, quiz, user))
             .collect(Collectors.toList());
     }
 
     public static List<QuizAttemptDTO> toDTOList(List<QuizAttempt> questions) {
-        if(questions == null || questions.isEmpty()) return null;
+        if(questions == null || questions.isEmpty()) return new ArrayList<>();
         return questions.stream()
             .map(QuizAttemptAssembler::toDTO)
             .collect(Collectors.toList());

src/main/java/com/studai/utils/exception/GlobalExceptionHandler.java

@@ -5,6 +5,7 @@
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.security.authentication.BadCredentialsException;
 import org.springframework.web.bind.annotation.ControllerAdvice;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.context.request.ServletWebRequest;
@@ -34,6 +35,22 @@ public ResponseEntity<Object> handleResourceNotFoundException(ResourceNotFoundEx
         return new ResponseEntity<>(errorResponse, new HttpHeaders(), HttpStatus.NOT_FOUND);
     }
 
+    @ExceptionHandler(BadCredentialsException.class)
+    public ResponseEntity<Object> handleBadCredentialsException(RuntimeException ex, WebRequest request) {
+        String path = ((ServletWebRequest) request).getRequest().getRequestURI();
+        logger.error("Bad credentials exception at {}: {}", path, ex.getMessage(), ex);
+
+        ErrorResponse errorResponse = ErrorResponse.builder()
+                .timestamp(new Date())
+                .status(HttpStatus.UNAUTHORIZED.value())
+                .error(HttpStatus.UNAUTHORIZED.getReasonPhrase())
+                .message(ex.getMessage())
+                .path(path)
+                .build();
+
+        return new ResponseEntity<>(errorResponse, new HttpHeaders(), HttpStatus.UNAUTHORIZED);
+    }
+
     @ExceptionHandler(RuntimeException.class)
     public ResponseEntity<Object> handleRuntimeException(RuntimeException ex, WebRequest request) {
         String path = ((ServletWebRequest) request).getRequest().getRequestURI();

src/main/java/com/studai/utils/exception/ResourceNotFoundException.java

@@ -1,4 +1,15 @@
 package com.studai.utils.exception;
 
 public class ResourceNotFoundException extends RuntimeException{
+
+    public ResourceNotFoundException(){};
+
+    public ResourceNotFoundException(String message) {
+        super(message);
+    }
+
+    public ResourceNotFoundException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
 }

src/test/java/com/studai/service/quiz/QuizServiceTest.java

@@ -21,9 +21,7 @@
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.time.LocalDateTime;
-import java.util.List;
-import java.util.Optional;
-import java.util.UUID;
+import java.util.*;
 
 import static org.junit.jupiter.api.Assertions.*;
 import static org.mockito.Mockito.*;
@@ -100,7 +98,7 @@ void testFindAll_Empty() {
         when(userService.getCurrentUser()).thenReturn(user);
         when(quizRepository.findByUser(user)).thenReturn(List.of());
 
-        assertThrows(ResourceNotFoundException.class, () -> quizService.findAll());
+        assertEquals(Collections.emptyList(), quizService.findAll());
     }
 
     @Test