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

package com.example.myproject.service;

import com.example.myproject.entity.Likes;
import com.example.myproject.entity.Post;
import com.example.myproject.entity.Users;
import com.example.myproject.repository.CollectionsRepository;
import com.example.myproject.repository.LikesRepository;
import com.example.myproject.repository.PostRepository;
import com.example.myproject.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;
import com.example.myproject.entity.Collections;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.*;

@Service
public class PostService {

    @Autowired
    private PostRepository postRepository;

    @Autowired
    private UserRepository userRepository;
    @Autowired
    private LikesRepository likesRepository;

    @Autowired
    private CollectionsRepository collectionsRepository;

    private static final String IMAGE_DIR = "uploads/post/";


    //创建帖子
    public Map<String, Object> createPost(Long userId, String postContent, String title, MultipartFile[] imageFiles) {
        // 查找用户信息
        Users user = userRepository.findById(Long.valueOf(userId)).orElseThrow(() -> new RuntimeException("User not found"));
        Post post = new Post();
        post.setUser_id(user.getUserId());
        post.setPostTime(new Date());
        post.setPostLikeNum(0);
        post.setPostCollectNum(0);
        post.setPostContent(postContent);
        post.setTitle(title);

        // 处理多张图片的上传
        StringBuilder imageUrlsBuilder = new StringBuilder();
        if (imageFiles != null && imageFiles.length > 0) {
            for (int i = 0; i < imageFiles.length; i++) {
                if (i > 0) {
                    imageUrlsBuilder.append(",");
                }
                try {
                    String imageUrl = saveImage(imageFiles[i]);
                    imageUrlsBuilder.append(imageUrl);
                } catch (IOException e) {
                    throw new RuntimeException("Image upload failed: " + e.getMessage());
                }
            }
        }
        post.setImageUrl(imageUrlsBuilder.toString());
        Post savedPost = postRepository.save(post);
        Map<String, Object> response = new HashMap<>();
        response.put("postNo", savedPost.getPostNo());
        response.put("message", "帖子创建成功");
        return response;
    }

    // 保存图片并返回图片的 URL
    public String saveImage(MultipartFile imageFile) throws IOException {
        String fileName = imageFile.getOriginalFilename();
        Path path = Paths.get(IMAGE_DIR + fileName);
        Files.createDirectories(path.getParent());
        Files.write(path, imageFile.getBytes());
        return "/images/" + fileName;
    }


    //编辑帖子
    public void updatePost(Long postId, Post post) {
        Post existingPost = postRepository.findById(postId).orElseThrow(() -> new RuntimeException("Post not found"));
        if (post.getTitle() != null) {
            existingPost.setTitle(post.getTitle());
        }
        if (post.getPostContent() != null) {
            existingPost.setPostContent(post.getPostContent());
        }
        if (post.getImageUrl() != null) {
            existingPost.setImageUrl(post.getImageUrl());
        }
        existingPost.setPostTime(post.getPostTime());
        // 保存更新后的帖子
        postRepository.save(existingPost);
    }

    //删除帖子
    public void deletePost(Long postId) {
        // 查找指定 ID 的帖子，如果不存在则抛出异常
        if (!postRepository.existsById(postId)) {
            throw new RuntimeException("Post not found");
        }
        // 删除该帖子
        postRepository.deleteById(postId);
    }

    //点赞帖子（已完成）
    public void likePost(Long postId, Long userId) {
        // 查找指定 ID 的帖子
        Post post = postRepository.findById(postId).orElseThrow(() -> new RuntimeException("Post not found"));
        post.setPostLikeNum(post.getPostLikeNum() + 1);

        // 保存帖子
        postRepository.save(post);
        Likes like = new Likes();
        like.setUserId(userId);
        like.setPostNo(postId);
        // 保存点赞记录
        likesRepository.save(like);
    }

    // 取消点赞帖子（已完成）
    public void unlikePost(Long postId, Long userId) {
        // 查找指定 ID 的帖子
        Post post = postRepository.findById(postId).orElseThrow(() -> new RuntimeException("Post not found"));

        // 如果点赞数大于 0，则减少点赞数
        if (post.getPostLikeNum() > 0) {
            post.setPostLikeNum(post.getPostLikeNum() - 1);
        }

        // 删除点赞表中对应的记录
        likesRepository.deleteLikeByUserIdAndPostNo(userId, postId);

        // 保存更新后的帖子
        postRepository.save(post);
    }


    // 获取帖子列表（已完成）
    public Map<String, Object> getAllPosts() {
        List<Post> posts = postRepository.findAll();
        List<Map<String, Object>> postList = new ArrayList<>();

        for (Post post : posts) {
            Map<String, Object> postMap = new LinkedHashMap<>();
            postMap.put("postNo", post.getPostNo());
            postMap.put("user_id", post.getUser_id());
            postMap.put("postContent", post.getPostContent());
            postMap.put("imgUrl", post.getImageUrl());
            postMap.put("title", post.getTitle());
            postMap.put("createdAt", post.getPostTime().toString());
            postMap.put("likeCount", post.getPostLikeNum());
            postMap.put("collectCount", post.getPostCollectNum());

            postList.add(postMap);
        }

        Map<String, Object> response = new HashMap<>();
        // 统计帖子数量
        response.put("total", postList.size());
        response.put("posts", postList);

        return response;
    }

    public Map<String, Object> getPostById(Long postId) {
        // 获取帖子
        Optional<Post> postOptional = postRepository.findById(postId);

        // 如果帖子存在
        if (postOptional.isPresent()) {
            Post post = postOptional.get();
            Map<String, Object> postData = new LinkedHashMap<>();
            postData.put("postNo", post.getPostNo());
            postData.put("user_id", post.getUser_id());
            Long userId = post.getUser_id();
            Users user = userRepository.findById(userId).orElse(null);

            if (user != null) {
                postData.put("username", user.getUsername());
                postData.put("avatar_url", user.getAvatarUrl());
            } else {
                postData.put("username", null);
                postData.put("avatar_url", null);
            }

            postData.put("postContent", post.getPostContent());
            postData.put("imageUrl", post.getImageUrl());
            postData.put("postTime", post.getPostTime());
            postData.put("postLikeNum", post.getPostLikeNum());
            postData.put("postCollectNum", post.getPostCollectNum());
            postData.put("title", post.getTitle());

            return postData;
        } else {
            throw new RuntimeException("Post not found with id: " + postId);
        }
    }


    //收藏
    public void collectPost(Long postId, Long userId) {
        Post post = postRepository.findById(postId).orElseThrow(() -> new RuntimeException("Post not found"));
        post.setPostCollectNum(post.getPostCollectNum() + 1);
        postRepository.save(post);

        // 添加到收藏表
        Collections collection = new Collections();
        collection.setUserId(userId);
        collection.setPostNo(postId);
        collectionsRepository.save(collection);
    }

    //取消收藏
    public void uncollectPost(Long postId, Long userId) {
        Post post = postRepository.findById(postId).orElseThrow(() -> new RuntimeException("Post not found"));
        // 减少帖子收藏数
        if (post.getPostCollectNum() > 0) {
            post.setPostCollectNum(post.getPostCollectNum() - 1);
            postRepository.save(post);
        }

        // 从收藏表中删除对应记录
        collectionsRepository.deleteLikeByUserIdAndPostNo(userId, postId);
    }



}