src/main/java/com/example/g8backend/mapper/PostMapper.java

package com.example.g8backend.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.example.g8backend.entity.Post;
import com.example.g8backend.entity.PostLike;
import org.apache.ibatis.annotations.*;
import java.util.List;
@Mapper
public interface PostMapper extends BaseMapper<Post> {
    // 获取用户的帖子
    List<Post> getPostsByUserId(@Param("userId") Long userId);
    // 搜索帖子
    @Select("<script>" +
            "SELECT DISTINCT p.* " + // 添加 DISTINCT 解决重复问题
            "FROM posts p " +
            "LEFT JOIN users u ON p.user_id = u.user_id " + // 只保留必要的 JOIN
            "WHERE (p.post_title LIKE CONCAT('%', #{keyword}, '%') " +
            "   OR p.post_content LIKE CONCAT('%', #{keyword}, '%')) " +
            "<if test='tagIds != null and tagIds.size() > 0'> " +
            "   AND p.post_id IN ( " + // 改为子查询确保正确过滤标签
            "       SELECT pt.post_id FROM post_tag pt " +
            "       WHERE pt.tag_id IN " +
            "       <foreach item='tagId' collection='tagIds' open='(' separator=',' close=')'> " +
            "           #{tagId} " +
            "       </foreach> " +
            "   ) " +
            "</if> " +
            "<if test='author != null and !author.isEmpty()'> " + // 增加空检查
            "   AND u.user_name LIKE CONCAT('%', #{author}, '%') " + // 改为模糊匹配
            "</if> " +
            "ORDER BY p.created_at DESC " + // 添加默认排序
            "LIMIT 1000" + // 添加结果限制防止性能问题
            "</script>")
    List<Post> searchPosts(@Param("keyword") String keyword,
                           @Param("tagIds") List<Long> tagIds,
                           @Param("author") String author);
    //  检查用户是否已经点赞该帖子
    @Select("SELECT EXISTS (SELECT 1 FROM post_likes WHERE user_id = #{userId} AND post_id = #{postId})")
    boolean existsByUserIdAndPostId(@Param("userId") Long userId, @Param("postId") Long postId);
    // 插入一条点赞记录
    @Insert("INSERT INTO post_likes (user_id, post_id) VALUES (#{userId}, #{postId})")
//    void insert(PostLike postLike);
    void insertLike(PostLike postLike);
    // 删除用户对帖子的点赞记录
    @Delete("DELETE FROM post_likes WHERE user_id = #{userId} AND post_id = #{postId}")
    void deleteLikeByUserIdAndPostId(@Param("userId") Long userId, @Param("postId") Long postId);
    // 获取某个帖子点赞数
    @Select("SELECT COUNT(*) FROM post_likes WHERE post_id = #{postId}")
    Long selectCount(@Param("postId") Long postId);
    @Update("UPDATE posts SET view_count = view_count + 1 WHERE post_id = #{postId}")
    void incrementViewCount(Long postId);
    @Select("SELECT COUNT(*) FROM post_likes WHERE post_id = #{postId}")
    Long selectLikeCount(Long postId);
    @Select("SELECT post_id FROM post_views WHERE user_id = #{userId}")
    List<Long> findViewedPostIds(Long userId);
    @Update({
            "<script>",
            "UPDATE posts",
            "SET hot_score = CASE",
            "  <foreach collection='posts' item='post'>",
            "    WHEN post_id = #{post.postId} THEN #{post.hotScore}",
            "  </foreach>",
            "END,",
            "last_calculated = NOW()",
            "WHERE post_id IN",
            "  <foreach collection='posts' item='post' open='(' separator=',' close=')'>",
            "    #{post.postId}",
            "  </foreach>",
            "</script>"
    })
    int batchUpdateHotScore(@Param("posts") List<Post> posts);

    @Update("UPDATE posts SET average_rating = #{averageRating}, rating_count = #{ratingCount} WHERE post_id = #{postId}")
    void updateRatingStats(
            @Param("postId") Long postId,
            @Param("averageRating") Double averageRating,
            @Param("ratingCount") Integer ratingCount
    );
}