feat: implement medal feature

backend/src/main/java/com/openisle/controller/MedalController.java

@@ -0,0 +1,23 @@
+package com.openisle.controller;
+
+import com.openisle.dto.MedalDto;
+import com.openisle.service.MedalService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/medals")
+@RequiredArgsConstructor
+public class MedalController {
+    private final MedalService medalService;
+
+    @GetMapping
+    public List<MedalDto> getMedals(@RequestParam(value = "userId", required = false) Long userId) {
+        return medalService.getMedals(userId);
+    }
+}

backend/src/main/java/com/openisle/dto/CommentMedalDto.java

@@ -0,0 +1,11 @@
+package com.openisle.dto;
+
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+@Data
+@EqualsAndHashCode(callSuper = true)
+public class CommentMedalDto extends MedalDto {
+    private long currentCommentCount;
+    private long targetCommentCount;
+}

backend/src/main/java/com/openisle/dto/MedalDto.java

@@ -0,0 +1,13 @@
+package com.openisle.dto;
+
+import com.openisle.model.MedalType;
+import lombok.Data;
+
+@Data
+public class MedalDto {
+    private String icon;
+    private String title;
+    private String description;
+    private MedalType type;
+    private boolean completed;
+}

backend/src/main/java/com/openisle/dto/PostMedalDto.java

@@ -0,0 +1,11 @@
+package com.openisle.dto;
+
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+@Data
+@EqualsAndHashCode(callSuper = true)
+public class PostMedalDto extends MedalDto {
+    private long currentPostCount;
+    private long targetPostCount;
+}

backend/src/main/java/com/openisle/dto/SeedUserMedalDto.java

@@ -0,0 +1,11 @@
+package com.openisle.dto;
+
+import java.time.LocalDateTime;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+@Data
+@EqualsAndHashCode(callSuper = true)
+public class SeedUserMedalDto extends MedalDto {
+    private LocalDateTime registerDate;
+}

backend/src/main/java/com/openisle/model/MedalType.java

@@ -0,0 +1,7 @@
+package com.openisle.model;
+
+public enum MedalType {
+    COMMENT,
+    POST,
+    SEED
+}

backend/src/main/java/com/openisle/repository/CommentRepository.java

@@ -30,4 +30,6 @@ public interface CommentRepository extends JpaRepository<Comment, Long> {
     @org.springframework.data.jpa.repository.Query("SELECT COUNT(c) FROM Comment c WHERE c.post.id = :postId")
     long countByPostId(@org.springframework.data.repository.query.Param("postId") Long postId);
 
+    long countByAuthor_Id(Long userId);
+
 }

backend/src/main/java/com/openisle/repository/PostRepository.java

@@ -93,4 +93,6 @@ public interface PostRepository extends JpaRepository<Post, Long> {
     long countByCategory_Id(Long categoryId);
 
     long countDistinctByTags_Id(Long tagId);
+
+    long countByAuthor_Id(Long userId);
 }

backend/src/main/java/com/openisle/service/MedalService.java

@@ -0,0 +1,84 @@
+package com.openisle.service;
+
+import com.openisle.dto.CommentMedalDto;
+import com.openisle.dto.MedalDto;
+import com.openisle.dto.PostMedalDto;
+import com.openisle.dto.SeedUserMedalDto;
+import com.openisle.model.MedalType;
+import com.openisle.repository.CommentRepository;
+import com.openisle.repository.PostRepository;
+import com.openisle.repository.UserRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+
+@Service
+@RequiredArgsConstructor
+public class MedalService {
+    private static final long COMMENT_TARGET = 100;
+    private static final long POST_TARGET = 100;
+    private static final LocalDateTime SEED_USER_DEADLINE = LocalDateTime.of(2025, 9, 16, 0, 0);
+
+    private final CommentRepository commentRepository;
+    private final PostRepository postRepository;
+    private final UserRepository userRepository;
+
+    public List<MedalDto> getMedals(Long userId) {
+        List<MedalDto> medals = new ArrayList<>();
+
+        CommentMedalDto commentMedal = new CommentMedalDto();
+        commentMedal.setIcon("comment.png");
+        commentMedal.setTitle("评论达人");
+        commentMedal.setDescription("评论超过100条");
+        commentMedal.setType(MedalType.COMMENT);
+        commentMedal.setTargetCommentCount(COMMENT_TARGET);
+        if (userId != null) {
+            long count = commentRepository.countByAuthor_Id(userId);
+            commentMedal.setCurrentCommentCount(count);
+            commentMedal.setCompleted(count >= COMMENT_TARGET);
+        } else {
+            commentMedal.setCurrentCommentCount(0);
+            commentMedal.setCompleted(false);
+        }
+        medals.add(commentMedal);
+
+        PostMedalDto postMedal = new PostMedalDto();
+        postMedal.setIcon("post.png");
+        postMedal.setTitle("发帖达人");
+        postMedal.setDescription("评论超过100条");
+        postMedal.setType(MedalType.POST);
+        postMedal.setTargetPostCount(POST_TARGET);
+        if (userId != null) {
+            long count = postRepository.countByAuthor_Id(userId);
+            postMedal.setCurrentPostCount(count);
+            postMedal.setCompleted(count >= POST_TARGET);
+        } else {
+            postMedal.setCurrentPostCount(0);
+            postMedal.setCompleted(false);
+        }
+        medals.add(postMedal);
+
+        SeedUserMedalDto seedUserMedal = new SeedUserMedalDto();
+        seedUserMedal.setIcon("seed.png");
+        seedUserMedal.setTitle("种子用户");
+        seedUserMedal.setDescription("2025.9.16前注册的用户");
+        seedUserMedal.setType(MedalType.SEED);
+        if (userId != null) {
+            userRepository.findById(userId).ifPresent(user -> {
+                seedUserMedal.setRegisterDate(user.getCreatedAt());
+                seedUserMedal.setCompleted(user.getCreatedAt().isBefore(SEED_USER_DEADLINE));
+            });
+            if (seedUserMedal.getRegisterDate() == null) {
+                seedUserMedal.setCompleted(false);
+            }
+        } else {
+            seedUserMedal.setCompleted(false);
+        }
+        medals.add(seedUserMedal);
+
+        return medals;
+    }
+}