Add image reference tracking

src/main/java/com/openisle/model/Image.java

@@ -0,0 +1,26 @@
+package com.openisle.model;
+
+import jakarta.persistence.*;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+/**
+ * Image entity tracking COS image reference counts.
+ */
+@Entity
+@Getter
+@Setter
+@NoArgsConstructor
+@Table(name = "images")
+public class Image {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(nullable = false, unique = true, length = 512)
+    private String url;
+
+    @Column(nullable = false)
+    private long refCount = 0;
+}

src/main/java/com/openisle/repository/ImageRepository.java

@@ -0,0 +1,13 @@
+package com.openisle.repository;
+
+import com.openisle.model.Image;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+/**
+ * Repository for images stored on COS.
+ */
+public interface ImageRepository extends JpaRepository<Image, Long> {
+    Optional<Image> findByUrl(String url);
+}

src/main/java/com/openisle/service/CommentService.java

@@ -31,6 +31,7 @@ public class CommentService {
     private final ReactionRepository reactionRepository;
     private final CommentSubscriptionRepository commentSubscriptionRepository;
     private final NotificationRepository notificationRepository;
+    private final ImageUploader imageUploader;
 
     public Comment addComment(String username, Long postId, String content) {
         User author = userRepository.findByUsername(username)
@@ -42,6 +43,7 @@ public class CommentService {
         comment.setPost(post);
         comment.setContent(content);
         comment = commentRepository.save(comment);
+        imageUploader.addReferences(imageUploader.extractUrls(content));
         if (!author.getId().equals(post.getAuthor().getId())) {
             notificationService.createNotification(post.getAuthor(), NotificationType.COMMENT_REPLY, post, comment, null, null, null, null);
         }
@@ -69,6 +71,7 @@ public class CommentService {
         comment.setParent(parent);
         comment.setContent(content);
         comment = commentRepository.save(comment);
+        imageUploader.addReferences(imageUploader.extractUrls(content));
         if (!author.getId().equals(parent.getAuthor().getId())) {
             notificationService.createNotification(parent.getAuthor(), NotificationType.COMMENT_REPLY, parent.getPost(), comment, null, null, null, null);
         }
@@ -150,6 +153,7 @@ public class CommentService {
         reactionRepository.findByComment(comment).forEach(reactionRepository::delete);
         commentSubscriptionRepository.findByComment(comment).forEach(commentSubscriptionRepository::delete);
         notificationRepository.deleteAll(notificationRepository.findByComment(comment));
+        imageUploader.removeReferences(imageUploader.extractUrls(comment.getContent()));
         commentRepository.delete(comment);
     }
 }

src/main/java/com/openisle/service/CosImageUploader.java

@@ -34,11 +34,13 @@ public class CosImageUploader extends ImageUploader {
 
     @org.springframework.beans.factory.annotation.Autowired
     public CosImageUploader(
+            com.openisle.repository.ImageRepository imageRepository,
             @Value("${cos.secret-id:}") String secretId,
             @Value("${cos.secret-key:}") String secretKey,
             @Value("${cos.region:ap-guangzhou}") String region,
             @Value("${cos.bucket-name:}") String bucketName,
             @Value("${cos.base-url:https://example.com}") String baseUrl) {
+        super(imageRepository, baseUrl);
         COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
         ClientConfig config = new ClientConfig(new Region(region));
         this.cosClient = new COSClient(cred, config);
@@ -48,7 +50,11 @@ public class CosImageUploader extends ImageUploader {
     }
 
     // for tests
-    CosImageUploader(COSClient cosClient, String bucketName, String baseUrl) {
+    CosImageUploader(COSClient cosClient,
+                     com.openisle.repository.ImageRepository imageRepository,
+                     String bucketName,
+                     String baseUrl) {
+        super(imageRepository, baseUrl);
         this.cosClient = cosClient;
         this.bucketName = bucketName;
         this.baseUrl = baseUrl;
@@ -56,7 +62,7 @@ public class CosImageUploader extends ImageUploader {
     }
 
     @Override
-    public CompletableFuture<String> upload(byte[] data, String filename) {
+    protected CompletableFuture<String> doUpload(byte[] data, String filename) {
         return CompletableFuture.supplyAsync(() -> {
             logger.debug("Uploading {} bytes as {}", data.length, filename);
             String ext = "";
@@ -81,4 +87,13 @@ public class CosImageUploader extends ImageUploader {
             return url;
         }, executor);
     }
+
+    @Override
+    protected void deleteFromStore(String key) {
+        try {
+            cosClient.deleteObject(bucketName, key);
+        } catch (Exception e) {
+            logger.warn("Failed to delete image {} from COS", key, e);
+        }
+    }
 }

src/main/java/com/openisle/service/ImageUploader.java

@@ -1,19 +1,101 @@
 package com.openisle.service;
 
+import com.openisle.model.Image;
+import com.openisle.repository.ImageRepository;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 /**
- * Abstract service for uploading images.
+ * Abstract service for uploading images and tracking their references.
  */
 public abstract class ImageUploader {
-    /**
+    private final ImageRepository imageRepository;
-     * Upload an image and return its accessible URL.
+    private final String baseUrl;
-     * @param data image binary data
+    private final Pattern urlPattern;
-     * @param filename name of the file
+
-     * @return accessible URL of the uploaded file
+    protected ImageUploader(ImageRepository imageRepository, String baseUrl) {
-     */
+        this.imageRepository = imageRepository;
+        if (baseUrl.endsWith("/")) {
+            this.baseUrl = baseUrl.substring(0, baseUrl.length() - 1);
+        } else {
+            this.baseUrl = baseUrl;
+        }
+        this.urlPattern = Pattern.compile(Pattern.quote(this.baseUrl) + "/[^\\s)]+");
+    }
+
     /**
      * Upload an image asynchronously and return a future of its accessible URL.
-     * Implementations should complete the future exceptionally on failures so
-     * callers can react accordingly.
      */
-    public abstract java.util.concurrent.CompletableFuture<String> upload(byte[] data, String filename);
+    public CompletableFuture<String> upload(byte[] data, String filename) {
+        return doUpload(data, filename).thenApply(url -> {
+            addReference(url);
+            return url;
+        });
+    }
+
+    protected abstract CompletableFuture<String> doUpload(byte[] data, String filename);
+
+    protected abstract void deleteFromStore(String key);
+
+    /** Extract COS URLs from text. */
+    public Set<String> extractUrls(String text) {
+        Set<String> set = new HashSet<>();
+        if (text == null) return set;
+        Matcher m = urlPattern.matcher(text);
+        while (m.find()) {
+            set.add(m.group());
+        }
+        return set;
+    }
+
+    public void addReferences(Set<String> urls) {
+        for (String u : urls) addReference(u);
+    }
+
+    public void removeReferences(Set<String> urls) {
+        for (String u : urls) removeReference(u);
+    }
+
+    public void adjustReferences(String oldText, String newText) {
+        Set<String> oldUrls = extractUrls(oldText);
+        Set<String> newUrls = extractUrls(newText);
+        for (String u : newUrls) {
+            if (!oldUrls.contains(u)) addReference(u);
+        }
+        for (String u : oldUrls) {
+            if (!newUrls.contains(u)) removeReference(u);
+        }
+    }
+
+    private void addReference(String url) {
+        if (!url.startsWith(baseUrl)) return;
+        imageRepository.findByUrl(url).ifPresentOrElse(img -> {
+            img.setRefCount(img.getRefCount() + 1);
+            imageRepository.save(img);
+        }, () -> {
+            Image img = new Image();
+            img.setUrl(url);
+            img.setRefCount(1);
+            imageRepository.save(img);
+        });
+    }
+
+    private void removeReference(String url) {
+        if (!url.startsWith(baseUrl)) return;
+        imageRepository.findByUrl(url).ifPresent(img -> {
+            long count = img.getRefCount() - 1;
+            if (count <= 0) {
+                imageRepository.delete(img);
+                String key = url.substring(baseUrl.length() + 1);
+                deleteFromStore(key);
+            } else {
+                img.setRefCount(count);
+                imageRepository.save(img);
+            }
+        });
+    }
 }

src/main/java/com/openisle/service/PostService.java

@@ -41,6 +41,7 @@ public class PostService {
     private final PostSubscriptionRepository postSubscriptionRepository;
     private final NotificationRepository notificationRepository;
     private final PostReadService postReadService;
+    private final ImageUploader imageUploader;
 
     @org.springframework.beans.factory.annotation.Autowired
     public PostService(PostRepository postRepository,
@@ -55,6 +56,7 @@ public class PostService {
                        PostSubscriptionRepository postSubscriptionRepository,
                        NotificationRepository notificationRepository,
                        PostReadService postReadService,
+                       ImageUploader imageUploader,
                        @Value("${app.post.publish-mode:DIRECT}") PublishMode publishMode) {
         this.postRepository = postRepository;
         this.userRepository = userRepository;
@@ -68,6 +70,7 @@ public class PostService {
         this.postSubscriptionRepository = postSubscriptionRepository;
         this.notificationRepository = notificationRepository;
         this.postReadService = postReadService;
+        this.imageUploader = imageUploader;
         this.publishMode = publishMode;
     }
 
@@ -106,6 +109,7 @@ public class PostService {
         post.setTags(new java.util.HashSet<>(tags));
         post.setStatus(publishMode == PublishMode.REVIEW ? PostStatus.PENDING : PostStatus.PUBLISHED);
         post = postRepository.save(post);
+        imageUploader.addReferences(imageUploader.extractUrls(content));
         if (post.getStatus() == PostStatus.PENDING) {
             java.util.List<User> admins = userRepository.findByRole(com.openisle.model.Role.ADMIN);
             for (User admin : admins) {
@@ -391,10 +395,13 @@ public class PostService {
             throw new IllegalArgumentException("Tag not found");
         }
         post.setTitle(title);
+        String oldContent = post.getContent();
         post.setContent(content);
         post.setCategory(category);
         post.setTags(new java.util.HashSet<>(tags));
-        return postRepository.save(post);
+        Post updated = postRepository.save(post);
+        imageUploader.adjustReferences(oldContent, content);
+        return updated;
     }
 
     @org.springframework.transaction.annotation.Transactional
@@ -413,6 +420,7 @@ public class PostService {
         postSubscriptionRepository.findByPost(post).forEach(postSubscriptionRepository::delete);
         notificationRepository.deleteAll(notificationRepository.findByPost(post));
         postReadService.deleteByPost(post);
+        imageUploader.removeReferences(imageUploader.extractUrls(post.getContent()));
         postRepository.delete(post);
     }
 

src/main/java/com/openisle/service/UserService.java

@@ -21,6 +21,7 @@ public class UserService {
     private final PasswordValidator passwordValidator;
     private final UsernameValidator usernameValidator;
     private final PasswordEncoder passwordEncoder = new BCryptPasswordEncoder();
+    private final ImageUploader imageUploader;
 
     public User register(String username, String email, String password, String reason, com.openisle.model.RegisterMode mode) {
         usernameValidator.validate(username);
@@ -120,8 +121,16 @@ public class UserService {
     public User updateAvatar(String username, String avatarUrl) {
         User user = userRepository.findByUsername(username)
                 .orElseThrow(() -> new com.openisle.exception.NotFoundException("User not found"));
+        String old = user.getAvatar();
         user.setAvatar(avatarUrl);
-        return userRepository.save(user);
+        User saved = userRepository.save(user);
+        if (old != null && !old.equals(avatarUrl)) {
+            imageUploader.removeReferences(java.util.Set.of(old));
+        }
+        if (avatarUrl != null) {
+            imageUploader.addReferences(java.util.Set.of(avatarUrl));
+        }
+        return saved;
     }
 
     public User updateReason(String username, String reason) {

src/test/java/com/openisle/service/CosImageUploaderTest.java

@@ -2,6 +2,7 @@ package com.openisle.service;
 
 import com.qcloud.cos.COSClient;
 import com.qcloud.cos.model.PutObjectRequest;
+import com.openisle.repository.ImageRepository;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -11,7 +12,8 @@ class CosImageUploaderTest {
     @Test
     void uploadReturnsUrl() {
         COSClient client = mock(COSClient.class);
-        CosImageUploader uploader = new CosImageUploader(client, "bucket", "http://cos.example.com");
+        ImageRepository repo = mock(ImageRepository.class);
+        CosImageUploader uploader = new CosImageUploader(client, repo, "bucket", "http://cos.example.com");
 
         String url = uploader.upload("data".getBytes(), "img.png").join();
 

src/test/java/com/openisle/service/PostServiceTest.java

@@ -24,11 +24,12 @@ class PostServiceTest {
         PostSubscriptionRepository subRepo = mock(PostSubscriptionRepository.class);
         NotificationRepository notificationRepo = mock(NotificationRepository.class);
         PostReadService postReadService = mock(PostReadService.class);
+        ImageUploader imageUploader = mock(ImageUploader.class);
 
         PostService service = new PostService(postRepo, userRepo, catRepo, tagRepo,
                 notifService, subService, commentService, commentRepo,
                 reactionRepo, subRepo, notificationRepo, postReadService,
-                PublishMode.DIRECT);
+                imageUploader, PublishMode.DIRECT);
 
         Post post = new Post();
         post.setId(1L);