@Transactional

@Service @RequiredArgsConstructor
public class BoardService {
    private final BoardRepository boardRepository;

    @Transactional(readOnly = true)   // 조회 → readOnly
    public Page<BoardDto> getBoardList(int page) {
        Pageable pageable = PageRequest.of(page, 10, Sort.by("createdAt").descending());
        Page<Board> boardPage = boardRepository.findAllByOrderByCreatedAtDesc(pageable);
        List<BoardDto> dtoList = boardPage.getContent().stream()
            .map(this::toDto).collect(Collectors.toList());
        return new PageImpl<>(dtoList, pageable, boardPage.getTotalElements());
    }

    @Transactional   // 조회수 UPDATE 포함이므로 readOnly 없음
    public BoardDto getDetail(Long id, User loginUser) {
        Board board = boardRepository.findById(id)
            .orElseThrow(() -> new CustomException("없는 게시글입니다.", 404));
        if (loginUser == null || !board.getUser().getId().equals(loginUser.getId()))
            board.setViewCount(board.getViewCount() + 1); // 더티체킹으로 UPDATE
        return toDto(board);
    }

    @Transactional   // INSERT
    public void write(BoardDto boardDto, User user) {
        Board board = new Board();
        board.setTitle(boardDto.getTitle());
        board.setContent(boardDto.getContent());
        board.setUser(user);
        boardRepository.save(board);
    }

    @Transactional   // UPDATE — 더티체킹 사용
    public void update(Long id, BoardDto boardDto, User user) {
        Board board = boardRepository.findById(id)
            .orElseThrow(() -> new CustomException("없는 게시글입니다.", 404));
        if (!board.getUser().getId().equals(user.getId()))
            throw new CustomException("수정 권한이 없습니다.", 403);
        board.setTitle(boardDto.getTitle());   // save() 없어도 더티체킹으로 UPDATE
        board.setContent(boardDto.getContent());
    }

    @Transactional   // DELETE
    public void delete(Long id, User user) {
        Board board = boardRepository.findById(id)
            .orElseThrow(() -> new CustomException("없는 게시글입니다.", 404));
        if (!board.getUser().getId().equals(user.getId()))
            throw new CustomException("삭제 권한이 없습니다.", 403);
        boardRepository.delete(board);
    }

    // toDto() — 변경 없음 (STEP 5에서 @Builder 방식으로 변경)
    private BoardDto toDto(Board board) {
        BoardDto dto = new BoardDto();
        dto.setId(board.getId());
        dto.setTitle(board.getTitle());
        dto.setContent(board.getContent());
        dto.setViewCount(board.getViewCount());
        dto.setUserId(board.getUser().getId());
        dto.setNickname(board.getUser().getNickname());
        dto.setUsername(board.getUser().getUsername());
        dto.setCreatedAt(board.getCreatedAt()
            .format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm")));
        return dto;
    }
}

@Service @RequiredArgsConstructor
public class UserService {
    private final UserRepository userRepository;
    private final BCryptPasswordEncoder bCryptPasswordEncoder;
    private final JwtUtil jwtUtil;

    @Value("${admin.code}")
    private String adminCode;

    @Transactional   // INSERT
    public void register(UserDto userDto) {
        if (userRepository.existsByUsername(userDto.getUsername()))
            throw new CustomException("이미 사용중인 아이디입니다.", 409);
        if (userRepository.existsByNickname(userDto.getNickname()))
            throw new CustomException("이미 사용중인 닉네임입니다.", 409);
        User user = new User();
        user.setUsername(userDto.getUsername());
        user.setPassword(bCryptPasswordEncoder.encode(userDto.getPassword()));
        user.setNickname(userDto.getNickname());
        if (adminCode.equals(userDto.getAdminCode())) user.setRole("ROLE_ADMIN");
        else user.setRole("ROLE_USER");
        userRepository.save(user);
    }

    @Transactional(readOnly = true)   // SELECT만 — JWT 발급은 DB 작업 아님
    public Map<String, String> login(String username, String password) {
        User user = userRepository.findByUsername(username)
            .orElseThrow(() -> new CustomException("아이디 또는 비밀번호가 틀렸습니다.", 401));
        if (!bCryptPasswordEncoder.matches(password, user.getPassword()))
            throw new CustomException("아이디 또는 비밀번호가 틀렸습니다.", 401);
        String token = jwtUtil.createToken(
            user.getUsername(), user.getNickname(), user.getRole()
        );
        return Map.of("token", token, "role", user.getRole());
    }
}

@Service @RequiredArgsConstructor
public class AdminService {
    private final UserRepository userRepository;
    private final BoardRepository boardRepository;

    @Transactional(readOnly = true)   // 조회만
    public List<UserDto> getAllUsers() {
        return userRepository.findAll().stream().map(user -> {
            UserDto dto = new UserDto();
            dto.setId(user.getId());
            dto.setUsername(user.getUsername());
            dto.setNickname(user.getNickname());
            dto.setRole(user.getRole());
            return dto;
        }).collect(Collectors.toList());
    }

    @Transactional(readOnly = true)   // 조회만
    public List<BoardDto> getAllBoards() {
        return boardRepository.findAll().stream().map(board -> {
            BoardDto dto = new BoardDto();
            dto.setId(board.getId());
            dto.setTitle(board.getTitle());
            dto.setNickname(board.getUser().getNickname());
            dto.setViewCount(board.getViewCount());
            return dto;
        }).collect(Collectors.toList());
    }

    @Transactional   // DELETE 2개 — 원자성 필수. 하나 실패하면 둘 다 롤백
    public void deleteUser(Long userId) {
        User user = userRepository.findById(userId)
            .orElseThrow(() -> new CustomException("없는 유저입니다.", 404));
        boardRepository.deleteByUser(user);   // FK 제약 → 게시글 먼저 삭제
        userRepository.delete(user);
    }

    @Transactional   // DELETE
    public void deleteBoard(Long boardId) {
        Board board = boardRepository.findById(boardId)
            .orElseThrow(() -> new CustomException("없는 게시글입니다.", 404));
        boardRepository.delete(board);
    }
}