// 核心功能1: 电影个性化推荐算法实现
public List<Movie> getPersonalizedRecommendations(Long userId, int limit) {
    // 获取用户观影历史
    List<UserWatchHistory> watchHistory = userWatchHistoryRepository.findByUserId(userId);
    
    // 获取用户评分数据
    List<UserRating> userRatings = userRatingRepository.findByUserId(userId);
    
    // 提取用户偏好特征
    Map<String, Double> userPreferences = new HashMap<>();
    for (UserRating rating : userRatings) {
        Movie movie = movieRepository.findById(rating.getMovieId()).orElse(null);
        if (movie != null) {
            // 根据评分权重增加类别偏好
            for (Category category : movie.getCategories()) {
                String categoryName = category.getName();
                userPreferences.put(categoryName, 
                    userPreferences.getOrDefault(categoryName, 0.0) + rating.getRating() * 0.2);
            }
            
            // 考虑导演因素
            userPreferences.put("director:" + movie.getDirector(), 
                userPreferences.getOrDefault("director:" + movie.getDirector(), 0.0) + rating.getRating() * 0.1);
        }
    }
    
    // 获取候选电影列表(排除已观看)
    Set<Long> watchedMovieIds = watchHistory.stream()
        .map(UserWatchHistory::getMovieId)
        .collect(Collectors.toSet());
    List<Movie> candidateMovies = movieRepository.findByIdNotIn(watchedMovieIds);
    
    // 计算每部电影与用户偏好的匹配度
    Map<Movie, Double> movieScores = new HashMap<>();
    for (Movie movie : candidateMovies) {
        double score = 0.0;
        
        // 类别匹配度
        for (Category category : movie.getCategories()) {
            score += userPreferences.getOrDefault(category.getName(), 0.0);
        }
        
        // 导演匹配度
        score += userPreferences.getOrDefault("director:" + movie.getDirector(), 0.0);
        
        // 考虑电影热度因素
        score += movie.getPopularityScore() * 0.3;
        
        movieScores.put(movie, score);
    }
    
    // 排序并返回推荐结果
    return movieScores.entrySet().stream()
        .sorted(Map.Entry.<Movie, Double>comparingByValue().reversed())
        .limit(limit)
        .map(Map.Entry::getKey)
        .collect(Collectors.toList());
}

// 核心功能2: 电影信息管理服务
@Transactional
public MovieDTO updateMovieInfo(Long movieId, MovieDTO movieDTO) {
    // 查找现有电影记录
    Movie existingMovie = movieRepository.findById(movieId)
        .orElseThrow(() -> new ResourceNotFoundException("电影不存在，ID: " + movieId));
    
    // 更新基本信息
    existingMovie.setTitle(movieDTO.getTitle());
    existingMovie.setDirector(movieDTO.getDirector());
    existingMovie.setReleaseDate(movieDTO.getReleaseDate());
    existingMovie.setDuration(movieDTO.getDuration());
    existingMovie.setDescription(movieDTO.getDescription());
    existingMovie.setRating(movieDTO.getRating());
    existingMovie.setCoverImage(movieDTO.getCoverImage());
    
    // 处理电影演员关系
    if (movieDTO.getActors() != null) {
        // 清除现有演员关联
        existingMovie.getActors().clear();
        
        // 添加新的演员关联
        for (ActorDTO actorDTO : movieDTO.getActors()) {
            Actor actor = null;
            if (actorDTO.getId() != null) {
                actor = actorRepository.findById(actorDTO.getId())
                    .orElseGet(() -> {
                        Actor newActor = new Actor();
                        newActor.setName(actorDTO.getName());
                        return actorRepository.save(newActor);
                    });
            } else {
                actor = actorRepository.findByName(actorDTO.getName())
                    .orElseGet(() -> {
                        Actor newActor = new Actor();
                        newActor.setName(actorDTO.getName());
                        return actorRepository.save(newActor);
                    });
            }
            existingMovie.getActors().add(actor);
        }
    }
    
    // 处理电影类别关系
    if (movieDTO.getCategories() != null) {
        existingMovie.getCategories().clear();
        
        for (CategoryDTO categoryDTO : movieDTO.getCategories()) {
            Category category = categoryRepository.findById(categoryDTO.getId())
                .orElseThrow(() -> new ResourceNotFoundException("类别不存在，ID: " + categoryDTO.getId()));
            existingMovie.getCategories().add(category);
        }
    }
    
    // 更新电影资源链接
    if (movieDTO.getResourceLinks() != null) {
        // 删除旧的资源链接
        resourceLinkRepository.deleteByMovieId(movieId);
        
        // 添加新的资源链接
        for (ResourceLinkDTO linkDTO : movieDTO.getResourceLinks()) {
            ResourceLink link = new ResourceLink();
            link.setMovie(existingMovie);
            link.setUrl(linkDTO.getUrl());
            link.setType(linkDTO.getType());
            link.setQuality(linkDTO.getQuality());
            resourceLinkRepository.save(link);
        }
    }
    
    // 保存更新后的电影信息
    Movie updatedMovie = movieRepository.save(existingMovie);
    
    // 更新电影搜索索引
    searchIndexService.updateMovieIndex(updatedMovie);
    
    // 转换为DTO并返回
    return movieMapper.toDTO(updatedMovie);
}

// 核心功能3: 交流论坛帖子管理
@Transactional
public ForumPostDTO createForumPost(ForumPostCreateRequest request, Long userId) {
    // 验证用户是否存在
    User user = userRepository.findById(userId)
        .orElseThrow(() -> new ResourceNotFoundException("用户不存在，ID: " + userId));
    
    // 检查用户是否被禁言
    if (user.getIsBanned()) {
        throw new UserBannedException("您的账号已被禁言，无法发布帖子");
    }
    
    // 检查内容是否违规
    ContentCheckResult checkResult = contentModerationService.checkContent(request.getContent());
    if (!checkResult.isApproved()) {
        throw new ContentViolationException("帖子内容包含违规信息: " + checkResult.getReason());
    }
    
    // 创建新帖子
    ForumPost post = new ForumPost();
    post.setTitle(request.getTitle());
    post.setContent(request.getContent());
    post.setUser(user);
    post.setCreatedAt(LocalDateTime.now());
    post.setUpdatedAt(LocalDateTime.now());
    post.setViewCount(0);
    post.setLikeCount(0);
    
    // 处理帖子分类
    if (request.getCategoryId() != null) {
        ForumCategory category = forumCategoryRepository.findById(request.getCategoryId())
            .orElseThrow(() -> new ResourceNotFoundException("论坛分类不存在，ID: " + request.getCategoryId()));
        post.setCategory(category);
        
        // 更新分类的帖子计数
        category.setPostCount(category.getPostCount() + 1);
        forumCategoryRepository.save(category);
    }
    
    // 处理帖子标签
    if (request.getTags() != null && !request.getTags().isEmpty()) {
        Set<ForumTag> tags = new HashSet<>();
        for (String tagName : request.getTags()) {
            ForumTag tag = forumTagRepository.findByName(tagName)
                .orElseGet(() -> {
                    ForumTag newTag = new ForumTag();
                    newTag.setName(tagName);
                    return forumTagRepository.save(newTag);
                });
            tags.add(tag);
        }
        post.setTags(tags);
    }
    
    // 处理关联电影
    if (request.getRelatedMovieId() != null) {
        Movie relatedMovie = movieRepository.findById(request.getRelatedMovieId())
            .orElseThrow(() -> new ResourceNotFoundException("电影不存在，ID: " + request.getRelatedMovieId()));
        post.setRelatedMovie(relatedMovie);
        
        // 更新电影的讨论度
        relatedMovie.setDiscussionCount(relatedMovie.getDiscussionCount() + 1);
        movieRepository.save(relatedMovie);
    }
    
    // 处理附加图片
    if (request.getAttachedImages() != null && !request.getAttachedImages().isEmpty()) {
        List<ForumPostImage> images = new ArrayList<>();
        for (String imageUrl : request.getAttachedImages()) {
            ForumPostImage image = new ForumPostImage();
            image.setPost(post);
            image.setImageUrl(imageUrl);
            images.add(image);
        }
        post.setImages(images);
    }
    
    // 保存帖子
    ForumPost savedPost = forumPostRepository.save(post);
    
    // 更新用户的发帖统计
    user.setPostCount(user.getPostCount() + 1);
    userRepository.save(user);
    
    // 发送新帖子通知给关注该用户的粉丝
    notificationService.sendNewPostNotification(savedPost);
    
    // 转换为DTO并返回
    return forumPostMapper.toDTO(savedPost);
}