feat: add dedicated mappers

backend/src/main/java/com/openisle/mapper/CategoryMapper.java

@@ -0,0 +1,25 @@
+package com.openisle.mapper;
+
+import com.openisle.dto.CategoryDto;
+import com.openisle.model.Category;
+import org.springframework.stereotype.Component;
+
+/** Mapper for category entities. */
+@Component
+public class CategoryMapper {
+
+    public CategoryDto toDto(Category c) {
+        return toDto(c, null);
+    }
+
+    public CategoryDto toDto(Category c, Long count) {
+        CategoryDto dto = new CategoryDto();
+        dto.setId(c.getId());
+        dto.setName(c.getName());
+        dto.setDescription(c.getDescription());
+        dto.setIcon(c.getIcon());
+        dto.setSmallIcon(c.getSmallIcon());
+        dto.setCount(count);
+        return dto;
+    }
+}

backend/src/main/java/com/openisle/mapper/CommentMapper.java

@@ -0,0 +1,42 @@
+package com.openisle.mapper;
+
+import com.openisle.dto.CommentDto;
+import com.openisle.model.Comment;
+import com.openisle.service.CommentService;
+import com.openisle.service.ReactionService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Component;
+
+import java.util.stream.Collectors;
+
+/** Mapper for comments including replies and reactions. */
+@Component
+@RequiredArgsConstructor
+public class CommentMapper {
+
+    private final CommentService commentService;
+    private final ReactionService reactionService;
+    private final ReactionMapper reactionMapper;
+    private final UserMapper userMapper;
+
+    public CommentDto toDto(Comment comment) {
+        CommentDto dto = new CommentDto();
+        dto.setId(comment.getId());
+        dto.setContent(comment.getContent());
+        dto.setCreatedAt(comment.getCreatedAt());
+        dto.setAuthor(userMapper.toAuthorDto(comment.getAuthor()));
+        dto.setReward(0);
+        return dto;
+    }
+
+    public CommentDto toDtoWithReplies(Comment comment) {
+        CommentDto dto = toDto(comment);
+        dto.setReplies(commentService.getReplies(comment.getId()).stream()
+                .map(this::toDtoWithReplies)
+                .collect(Collectors.toList()));
+        dto.setReactions(reactionService.getReactionsForComment(comment.getId()).stream()
+                .map(reactionMapper::toDto)
+                .collect(Collectors.toList()));
+        return dto;
+    }
+}

backend/src/main/java/com/openisle/mapper/DraftMapper.java

@@ -0,0 +1,24 @@
+package com.openisle.mapper;
+
+import com.openisle.dto.DraftDto;
+import com.openisle.model.Draft;
+import org.springframework.stereotype.Component;
+
+import java.util.stream.Collectors;
+
+/** Mapper for draft entities. */
+@Component
+public class DraftMapper {
+
+    public DraftDto toDto(Draft draft) {
+        DraftDto dto = new DraftDto();
+        dto.setId(draft.getId());
+        dto.setTitle(draft.getTitle());
+        dto.setContent(draft.getContent());
+        if (draft.getCategory() != null) {
+            dto.setCategoryId(draft.getCategory().getId());
+        }
+        dto.setTagIds(draft.getTags().stream().map(tag -> tag.getId()).collect(Collectors.toList()));
+        return dto;
+    }
+}

backend/src/main/java/com/openisle/mapper/NotificationMapper.java

@@ -0,0 +1,47 @@
+package com.openisle.mapper;
+
+import com.openisle.dto.NotificationDto;
+import com.openisle.dto.PostSummaryDto;
+import com.openisle.model.Comment;
+import com.openisle.model.Notification;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Component;
+
+/** Mapper for notifications. */
+@Component
+@RequiredArgsConstructor
+public class NotificationMapper {
+
+    private final CommentMapper commentMapper;
+    private final UserMapper userMapper;
+
+    public NotificationDto toDto(Notification n) {
+        NotificationDto dto = new NotificationDto();
+        dto.setId(n.getId());
+        dto.setType(n.getType());
+        if (n.getPost() != null) {
+            PostSummaryDto postDto = new PostSummaryDto();
+            postDto.setId(n.getPost().getId());
+            postDto.setTitle(n.getPost().getTitle());
+            dto.setPost(postDto);
+        }
+        if (n.getComment() != null) {
+            dto.setComment(commentMapper.toDto(n.getComment()));
+            Comment parent = n.getComment().getParent();
+            if (parent != null) {
+                dto.setParentComment(commentMapper.toDto(parent));
+            }
+        }
+        if (n.getFromUser() != null) {
+            dto.setFromUser(userMapper.toAuthorDto(n.getFromUser()));
+        }
+        if (n.getReactionType() != null) {
+            dto.setReactionType(n.getReactionType());
+        }
+        dto.setApproved(n.getApproved());
+        dto.setContent(n.getContent());
+        dto.setRead(n.isRead());
+        dto.setCreatedAt(n.getCreatedAt());
+        return dto;
+    }
+}

backend/src/main/java/com/openisle/mapper/PostMapper.java

@@ -1,7 +1,12 @@
 package com.openisle.mapper;
 
-import com.openisle.dto.*;
-import com.openisle.model.*;
+import com.openisle.dto.CommentDto;
+import com.openisle.dto.PostDetailDto;
+import com.openisle.dto.PostSummaryDto;
+import com.openisle.dto.ReactionDto;
+import com.openisle.model.CommentSort;
+import com.openisle.model.Post;
+import com.openisle.model.User;
 import com.openisle.service.CommentService;
 import com.openisle.service.ReactionService;
 import com.openisle.service.SubscriptionService;
@@ -12,9 +17,7 @@ import java.time.LocalDateTime;
 import java.util.List;
 import java.util.stream.Collectors;
 
-/**
- * Mapper responsible for converting domain models into DTOs.
- */
+/** Mapper responsible for converting posts into DTOs. */
 @Component
 @RequiredArgsConstructor
 public class PostMapper {
@@ -22,6 +25,11 @@ public class PostMapper {
     private final CommentService commentService;
     private final ReactionService reactionService;
     private final SubscriptionService subscriptionService;
+    private final CommentMapper commentMapper;
+    private final ReactionMapper reactionMapper;
+    private final UserMapper userMapper;
+    private final TagMapper tagMapper;
+    private final CategoryMapper categoryMapper;
 
     public PostSummaryDto toSummaryDto(Post post) {
         PostSummaryDto dto = new PostSummaryDto();
@@ -34,7 +42,7 @@ public class PostMapper {
         applyCommon(post, dto);
         List<CommentDto> comments = commentService.getCommentsForPost(post.getId(), CommentSort.OLDEST)
                 .stream()
-                .map(this::toCommentDtoWithReplies)
+                .map(commentMapper::toDtoWithReplies)
                 .collect(Collectors.toList());
         dto.setComments(comments);
         dto.setSubscribed(viewer != null && subscriptionService.isPostSubscribed(viewer, post.getId()));
@@ -46,96 +54,25 @@ public class PostMapper {
         dto.setTitle(post.getTitle());
         dto.setContent(post.getContent());
         dto.setCreatedAt(post.getCreatedAt());
-        dto.setAuthor(toAuthorDto(post.getAuthor()));
-        dto.setCategory(toCategoryDto(post.getCategory()));
-        dto.setTags(post.getTags().stream().map(this::toTagDto).collect(Collectors.toList()));
+        dto.setAuthor(userMapper.toAuthorDto(post.getAuthor()));
+        dto.setCategory(categoryMapper.toDto(post.getCategory()));
+        dto.setTags(post.getTags().stream().map(tagMapper::toDto).collect(Collectors.toList()));
         dto.setViews(post.getViews());
         dto.setStatus(post.getStatus());
         dto.setPinnedAt(post.getPinnedAt());
 
         List<ReactionDto> reactions = reactionService.getReactionsForPost(post.getId())
                 .stream()
-                .map(this::toReactionDto)
+                .map(reactionMapper::toDto)
                 .collect(Collectors.toList());
         dto.setReactions(reactions);
 
         List<User> participants = commentService.getParticipants(post.getId(), 5);
-        dto.setParticipants(participants.stream().map(this::toAuthorDto).collect(Collectors.toList()));
+        dto.setParticipants(participants.stream().map(userMapper::toAuthorDto).collect(Collectors.toList()));
 
         LocalDateTime last = commentService.getLastCommentTime(post.getId());
         dto.setLastReplyAt(last != null ? last : post.getCreatedAt());
         dto.setReward(0);
         dto.setSubscribed(false);
     }
-
-    private CommentDto toCommentDtoWithReplies(Comment comment) {
-        CommentDto dto = toCommentDto(comment);
-        List<CommentDto> replies = commentService.getReplies(comment.getId()).stream()
-                .map(this::toCommentDtoWithReplies)
-                .collect(Collectors.toList());
-        dto.setReplies(replies);
-
-        List<ReactionDto> reactions = reactionService.getReactionsForComment(comment.getId())
-                .stream()
-                .map(this::toReactionDto)
-                .collect(Collectors.toList());
-        dto.setReactions(reactions);
-
-        return dto;
-    }
-
-    private CommentDto toCommentDto(Comment comment) {
-        CommentDto dto = new CommentDto();
-        dto.setId(comment.getId());
-        dto.setContent(comment.getContent());
-        dto.setCreatedAt(comment.getCreatedAt());
-        dto.setAuthor(toAuthorDto(comment.getAuthor()));
-        dto.setReward(0);
-        return dto;
-    }
-
-    private ReactionDto toReactionDto(Reaction reaction) {
-        ReactionDto dto = new ReactionDto();
-        dto.setId(reaction.getId());
-        dto.setType(reaction.getType());
-        dto.setUser(reaction.getUser().getUsername());
-        if (reaction.getPost() != null) {
-            dto.setPostId(reaction.getPost().getId());
-        }
-        if (reaction.getComment() != null) {
-            dto.setCommentId(reaction.getComment().getId());
-        }
-        dto.setReward(0);
-        return dto;
-    }
-
-    private CategoryDto toCategoryDto(Category category) {
-        CategoryDto dto = new CategoryDto();
-        dto.setId(category.getId());
-        dto.setName(category.getName());
-        dto.setDescription(category.getDescription());
-        dto.setIcon(category.getIcon());
-        dto.setSmallIcon(category.getSmallIcon());
-        return dto;
-    }
-
-    private TagDto toTagDto(Tag tag) {
-        TagDto dto = new TagDto();
-        dto.setId(tag.getId());
-        dto.setName(tag.getName());
-        dto.setDescription(tag.getDescription());
-        dto.setIcon(tag.getIcon());
-        dto.setSmallIcon(tag.getSmallIcon());
-        dto.setCreatedAt(tag.getCreatedAt());
-        return dto;
-    }
-
-    private AuthorDto toAuthorDto(User user) {
-        AuthorDto dto = new AuthorDto();
-        dto.setId(user.getId());
-        dto.setUsername(user.getUsername());
-        dto.setAvatar(user.getAvatar());
-        return dto;
-    }
 }
-

backend/src/main/java/com/openisle/mapper/ReactionMapper.java

@@ -0,0 +1,25 @@
+package com.openisle.mapper;
+
+import com.openisle.dto.ReactionDto;
+import com.openisle.model.Reaction;
+import org.springframework.stereotype.Component;
+
+/** Mapper for reactions. */
+@Component
+public class ReactionMapper {
+
+    public ReactionDto toDto(Reaction reaction) {
+        ReactionDto dto = new ReactionDto();
+        dto.setId(reaction.getId());
+        dto.setType(reaction.getType());
+        dto.setUser(reaction.getUser().getUsername());
+        if (reaction.getPost() != null) {
+            dto.setPostId(reaction.getPost().getId());
+        }
+        if (reaction.getComment() != null) {
+            dto.setCommentId(reaction.getComment().getId());
+        }
+        dto.setReward(0);
+        return dto;
+    }
+}

backend/src/main/java/com/openisle/mapper/TagMapper.java

@@ -0,0 +1,26 @@
+package com.openisle.mapper;
+
+import com.openisle.dto.TagDto;
+import com.openisle.model.Tag;
+import org.springframework.stereotype.Component;
+
+/** Mapper for tag entities. */
+@Component
+public class TagMapper {
+
+    public TagDto toDto(Tag tag) {
+        return toDto(tag, null);
+    }
+
+    public TagDto toDto(Tag tag, Long count) {
+        TagDto dto = new TagDto();
+        dto.setId(tag.getId());
+        dto.setName(tag.getName());
+        dto.setDescription(tag.getDescription());
+        dto.setIcon(tag.getIcon());
+        dto.setSmallIcon(tag.getSmallIcon());
+        dto.setCreatedAt(tag.getCreatedAt());
+        dto.setCount(count);
+        return dto;
+    }
+}

backend/src/main/java/com/openisle/mapper/UserMapper.java

@@ -0,0 +1,104 @@
+package com.openisle.mapper;
+
+import com.openisle.dto.*;
+import com.openisle.model.Comment;
+import com.openisle.model.Post;
+import com.openisle.model.User;
+import com.openisle.service.*;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.security.core.Authentication;
+import org.springframework.stereotype.Component;
+
+/** Mapper for user related DTOs. */
+@Component
+@RequiredArgsConstructor
+public class UserMapper {
+
+    private final SubscriptionService subscriptionService;
+    private final PostService postService;
+    private final CommentService commentService;
+    private final ReactionService reactionService;
+    private final UserVisitService userVisitService;
+    private final PostReadService postReadService;
+    private final LevelService levelService;
+
+    @Value("${app.snippet-length:50}")
+    private int snippetLength;
+
+    public AuthorDto toAuthorDto(User user) {
+        AuthorDto dto = new AuthorDto();
+        dto.setId(user.getId());
+        dto.setUsername(user.getUsername());
+        dto.setAvatar(user.getAvatar());
+        return dto;
+    }
+
+    public UserDto toDto(User user, Authentication viewer) {
+        UserDto dto = new UserDto();
+        dto.setId(user.getId());
+        dto.setUsername(user.getUsername());
+        dto.setEmail(user.getEmail());
+        dto.setAvatar(user.getAvatar());
+        dto.setRole(user.getRole().name());
+        dto.setIntroduction(user.getIntroduction());
+        dto.setFollowers(subscriptionService.countSubscribers(user.getUsername()));
+        dto.setFollowing(subscriptionService.countSubscribed(user.getUsername()));
+        dto.setCreatedAt(user.getCreatedAt());
+        dto.setLastPostTime(postService.getLastPostTime(user.getUsername()));
+        dto.setLastCommentTime(commentService.getLastCommentTimeOfUserByUserId(user.getId()));
+        dto.setTotalViews(postService.getTotalViews(user.getUsername()));
+        dto.setVisitedDays(userVisitService.countVisits(user.getUsername()));
+        dto.setReadPosts(postReadService.countReads(user.getUsername()));
+        dto.setLikesSent(reactionService.countLikesSent(user.getUsername()));
+        dto.setLikesReceived(reactionService.countLikesReceived(user.getUsername()));
+        dto.setExperience(user.getExperience());
+        dto.setCurrentLevel(levelService.getLevel(user.getExperience()));
+        dto.setNextLevelExp(levelService.nextLevelExp(user.getExperience()));
+        if (viewer != null) {
+            dto.setSubscribed(subscriptionService.isSubscribed(viewer.getName(), user.getUsername()));
+        } else {
+            dto.setSubscribed(false);
+        }
+        return dto;
+    }
+
+    public UserDto toDto(User user) {
+        return toDto(user, null);
+    }
+
+    public PostMetaDto toMetaDto(Post post) {
+        PostMetaDto dto = new PostMetaDto();
+        dto.setId(post.getId());
+        dto.setTitle(post.getTitle());
+        String content = post.getContent();
+        if (content == null) {
+            content = "";
+        }
+        if (snippetLength >= 0) {
+            dto.setSnippet(content.length() > snippetLength ? content.substring(0, snippetLength) : content);
+        } else {
+            dto.setSnippet(content);
+        }
+        dto.setCreatedAt(post.getCreatedAt());
+        dto.setCategory(post.getCategory().getName());
+        dto.setViews(post.getViews());
+        return dto;
+    }
+
+    public CommentInfoDto toCommentInfoDto(Comment comment) {
+        CommentInfoDto dto = new CommentInfoDto();
+        dto.setId(comment.getId());
+        dto.setContent(comment.getContent());
+        dto.setCreatedAt(comment.getCreatedAt());
+        dto.setPost(toMetaDto(comment.getPost()));
+        if (comment.getParent() != null) {
+            ParentCommentDto pc = new ParentCommentDto();
+            pc.setId(comment.getParent().getId());
+            pc.setAuthor(comment.getParent().getAuthor().getUsername());
+            pc.setContent(comment.getParent().getContent());
+            dto.setParentComment(pc);
+        }
+        return dto;
+    }
+}