src/main/java/com/example/myproject/service/UserFollowService.java

package com.example.myproject.service;

import com.example.myproject.entity.Users;
import com.example.myproject.entity.UserFollow;
import com.example.myproject.repository.UserFollowRepository;
import com.example.myproject.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.*;

@Service
public class UserFollowService {

    @Autowired
    private UserFollowRepository userFollowRepository;

    @Autowired
    private UserRepository userRepository;

    // 用户关注操作
    public Map<String, Object> follow(Long followerId, Long followedId) {
        if (followerId.equals(followedId)) {
            Map<String, Object> response = new LinkedHashMap<>();
            response.put("status", "error");
            response.put("message", "不能关注自己");
            return response;
        }

        // 检查是否已关注该用户
        UserFollow existingFollow = userFollowRepository.findByFollowerIdAndFollowedId(followerId, followedId);
        if (existingFollow == null) {
            // 创建新的关注记录
            UserFollow userFollow = new UserFollow();
            userFollow.setFollowerId(followerId);
            userFollow.setFollowedId(followedId);
            userFollow.setFollowTime(new java.util.Date());

            userFollowRepository.save(userFollow);

            // 返回关注成功响应
            Map<String, Object> response = new LinkedHashMap<>();
            response.put("status", "success");
            response.put("message", "关注成功");
            return response;
        } else {
            Map<String, Object> response = new LinkedHashMap<>();
            response.put("status", "error");
            response.put("message", "已经关注该用户");
            return response;
        }
    }

    // 取消关注操作
    public Map<String, Object> unfollow(Long followerId, Long followedId) {
        UserFollow userFollow = userFollowRepository.findByFollowerIdAndFollowedId(followerId, followedId);

        if (userFollow != null) {
            userFollowRepository.delete(userFollow);

            Map<String, Object> response = new LinkedHashMap<>();
            response.put("status", "success");
            response.put("message", "取消关注成功");
            return response;
        } else {
            Map<String, Object> response = new LinkedHashMap<>();
            response.put("status", "error");
            response.put("message", "未找到关注关系");
            return response;
        }
    }

    // 获取某个用户的所有粉丝
    public Map<String, Object> getFollowers(Long userId) {
        List<UserFollow> followers = userFollowRepository.findByFollowedId(userId);

        List<Map<String, Object>> followersList = new ArrayList<>();
        for (UserFollow follow : followers) {
            // 获取粉丝的用户信息
            Users follower = userRepository.findById(follow.getFollowerId()).orElse(null);
            if (follower != null) {
                Map<String, Object> followerInfo = new LinkedHashMap<>();
                followerInfo.put("user_id", follower.getUserId());
                followerInfo.put("username", follower.getUsername());
                followerInfo.put("avatar_url", follower.getAvatarUrl());
                followersList.add(followerInfo);
            }
        }

        // 返回响应数据
        Map<String, Object> response = new LinkedHashMap<>();
        response.put("status", "success");
        response.put("total", followersList.size());
        response.put("followers", followersList);

        return response;
    }

    // 获取某个用户的所有关注用户
    public Map<String, Object> getFollowing(Long userId) {
        List<UserFollow> following = userFollowRepository.findByFollowerId(userId);

        List<Map<String, Object>> followingList = new ArrayList<>();
        for (UserFollow follow : following) {
            // 获取被关注的用户信息
            Users followedUser = userRepository.findById(follow.getFollowedId()).orElse(null);
            if (followedUser != null) {
                Map<String, Object> followingInfo = new HashMap<>();
                followingInfo.put("user_id", followedUser.getUserId());
                followingInfo.put("username", followedUser.getUsername());
                followingInfo.put("avatar_url", followedUser.getAvatarUrl());
                followingList.add(followingInfo);
            }
        }
        Map<String, Object> response = new HashMap<>();
        response.put("status", "success");
        response.put("total", followingList.size());
        response.put("following", followingList);

        return response;
    }
}