feat: implement lottery post type

backend/src/main/java/com/openisle/config/SchedulerConfig.java

@@ -0,0 +1,20 @@
+package com.openisle.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.scheduling.annotation.EnableScheduling;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
+import org.springframework.scheduling.TaskScheduler;
+
+@Configuration
+@EnableScheduling
+public class SchedulerConfig {
+    @Bean
+    public TaskScheduler taskScheduler() {
+        ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
+        scheduler.setPoolSize(2);
+        scheduler.setThreadNamePrefix("lottery-");
+        scheduler.initialize();
+        return scheduler;
+    }
+}

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

@@ -39,7 +39,9 @@ public class PostController {
             return ResponseEntity.badRequest().build();
         }
         Post post = postService.createPost(auth.getName(), req.getCategoryId(),
-                req.getTitle(), req.getContent(), req.getTagIds());
+                req.getTitle(), req.getContent(), req.getTagIds(),
+                req.getType(), req.getPrizeDescription(), req.getPrizeIcon(),
+                req.getPrizeCount(), req.getStartTime(), req.getEndTime());
         draftService.deleteDraft(auth.getName());
         PostDetailDto dto = postMapper.toDetailDto(post, auth.getName());
         dto.setReward(levelService.awardForPost(auth.getName()));
@@ -67,6 +69,12 @@ public class PostController {
         return ResponseEntity.ok(postMapper.toDetailDto(post, viewer));
     }
 
+    @PostMapping("/{id}/lottery/join")
+    public ResponseEntity<Void> joinLottery(@PathVariable Long id, Authentication auth) {
+        postService.joinLottery(id, auth.getName());
+        return ResponseEntity.ok().build();
+    }
+
     @GetMapping
     public List<PostSummaryDto> listPosts(@RequestParam(value = "categoryId", required = false) Long categoryId,
                                    @RequestParam(value = "categoryIds", required = false) List<Long> categoryIds,

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

@@ -0,0 +1,17 @@
+package com.openisle.dto;
+
+import lombok.Data;
+import java.time.LocalDateTime;
+import java.util.List;
+
+/** Metadata for lottery posts. */
+@Data
+public class LotteryDto {
+    private String prizeDescription;
+    private String prizeIcon;
+    private int prizeCount;
+    private LocalDateTime startTime;
+    private LocalDateTime endTime;
+    private List<AuthorDto> participants;
+    private List<AuthorDto> winners;
+}

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

@@ -2,8 +2,11 @@ package com.openisle.dto;
 
 import lombok.Data;
 
+import java.time.LocalDateTime;
 import java.util.List;
 
+import com.openisle.model.PostType;
+
 /**
  * Request body for creating or updating a post.
  */
@@ -14,5 +17,13 @@ public class PostRequest {
     private String content;
     private List<Long> tagIds;
     private String captcha;
+
+    // optional for lottery posts
+    private PostType type;
+    private String prizeDescription;
+    private String prizeIcon;
+    private Integer prizeCount;
+    private LocalDateTime startTime;
+    private LocalDateTime endTime;
 }
 

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

@@ -1,6 +1,7 @@
 package com.openisle.dto;
 
 import com.openisle.model.PostStatus;
+import com.openisle.model.PostType;
 import lombok.Data;
 
 import java.time.LocalDateTime;
@@ -28,5 +29,7 @@ public class PostSummaryDto {
     private boolean subscribed;
     private int reward;
     private int pointReward;
+    private PostType type;
+    private LotteryDto lottery;
 }
 

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

@@ -4,8 +4,10 @@ import com.openisle.dto.CommentDto;
 import com.openisle.dto.PostDetailDto;
 import com.openisle.dto.PostSummaryDto;
 import com.openisle.dto.ReactionDto;
+import com.openisle.dto.LotteryDto;
 import com.openisle.model.CommentSort;
 import com.openisle.model.Post;
+import com.openisle.model.LotteryPost;
 import com.openisle.model.User;
 import com.openisle.service.CommentService;
 import com.openisle.service.ReactionService;
@@ -75,5 +77,18 @@ public class PostMapper {
         dto.setLastReplyAt(last != null ? last : post.getCreatedAt());
         dto.setReward(0);
         dto.setSubscribed(false);
+        dto.setType(post.getType());
+
+        if (post instanceof LotteryPost lp) {
+            LotteryDto l = new LotteryDto();
+            l.setPrizeDescription(lp.getPrizeDescription());
+            l.setPrizeIcon(lp.getPrizeIcon());
+            l.setPrizeCount(lp.getPrizeCount());
+            l.setStartTime(lp.getStartTime());
+            l.setEndTime(lp.getEndTime());
+            l.setParticipants(lp.getParticipants().stream().map(userMapper::toAuthorDto).collect(Collectors.toList()));
+            l.setWinners(lp.getWinners().stream().map(userMapper::toAuthorDto).collect(Collectors.toList()));
+            dto.setLottery(l);
+        }
     }
 }

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

@@ -0,0 +1,46 @@
+package com.openisle.model;
+
+import jakarta.persistence.*;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+import java.time.LocalDateTime;
+import java.util.HashSet;
+import java.util.Set;
+
+@Entity
+@Table(name = "lottery_posts")
+@Getter
+@Setter
+@NoArgsConstructor
+@PrimaryKeyJoinColumn(name = "post_id")
+public class LotteryPost extends Post {
+
+    @Column
+    private String prizeDescription;
+
+    @Column
+    private String prizeIcon;
+
+    @Column(nullable = false)
+    private int prizeCount;
+
+    @Column
+    private LocalDateTime startTime;
+
+    @Column
+    private LocalDateTime endTime;
+
+    @ManyToMany
+    @JoinTable(name = "lottery_participants",
+            joinColumns = @JoinColumn(name = "post_id"),
+            inverseJoinColumns = @JoinColumn(name = "user_id"))
+    private Set<User> participants = new HashSet<>();
+
+    @ManyToMany
+    @JoinTable(name = "lottery_winners",
+            joinColumns = @JoinColumn(name = "post_id"),
+            inverseJoinColumns = @JoinColumn(name = "user_id"))
+    private Set<User> winners = new HashSet<>();
+}

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

@@ -9,11 +9,11 @@ import org.hibernate.annotations.CreationTimestamp;
 import java.util.HashSet;
 import java.util.Set;
 
+import java.time.LocalDateTime;
+
 import com.openisle.model.Tag;
 
 
-import java.time.LocalDateTime;
-
 /**
  * Post entity representing an article posted by a user.
  */
@@ -22,6 +22,7 @@ import java.time.LocalDateTime;
 @Setter
 @NoArgsConstructor
 @Table(name = "posts")
+@Inheritance(strategy = InheritanceType.JOINED)
 public class Post {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
@@ -59,6 +60,10 @@ public class Post {
     @Column(nullable = false)
     private PostStatus status = PostStatus.PUBLISHED;
 
+    @Enumerated(EnumType.STRING)
+    @Column(nullable = false)
+    private PostType type = PostType.NORMAL;
+
     @Column
     private LocalDateTime pinnedAt;
 

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

@@ -0,0 +1,6 @@
+package com.openisle.model;
+
+public enum PostType {
+    NORMAL,
+    LOTTERY
+}

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

@@ -0,0 +1,7 @@
+package com.openisle.repository;
+
+import com.openisle.model.LotteryPost;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface LotteryPostRepository extends JpaRepository<LotteryPost, Long> {
+}

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

@@ -2,12 +2,15 @@ package com.openisle.service;
 
 import com.openisle.model.Post;
 import com.openisle.model.PostStatus;
+import com.openisle.model.PostType;
 import com.openisle.model.PublishMode;
 import com.openisle.model.User;
 import com.openisle.model.Category;
 import com.openisle.model.Comment;
 import com.openisle.model.NotificationType;
+import com.openisle.model.LotteryPost;
 import com.openisle.repository.PostRepository;
+import com.openisle.repository.LotteryPostRepository;
 import com.openisle.repository.UserRepository;
 import com.openisle.repository.CategoryRepository;
 import com.openisle.repository.TagRepository;
@@ -21,6 +24,8 @@ import com.openisle.model.Role;
 import com.openisle.exception.RateLimitException;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Service;
+import org.springframework.scheduling.TaskScheduler;
+import com.openisle.service.EmailSender;
 
 import java.util.List;
 import org.springframework.data.domain.PageRequest;
@@ -28,12 +33,19 @@ import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
 import org.springframework.transaction.annotation.Transactional;
 
+import java.time.ZoneId;
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+
 @Service
 public class PostService {
     private final PostRepository postRepository;
     private final UserRepository userRepository;
     private final CategoryRepository categoryRepository;
     private final TagRepository tagRepository;
+    private final LotteryPostRepository lotteryPostRepository;
     private PublishMode publishMode;
     private final NotificationService notificationService;
     private final SubscriptionService subscriptionService;
@@ -44,12 +56,15 @@ public class PostService {
     private final NotificationRepository notificationRepository;
     private final PostReadService postReadService;
     private final ImageUploader imageUploader;
+    private final TaskScheduler taskScheduler;
+    private final EmailSender emailSender;
 
     @org.springframework.beans.factory.annotation.Autowired
     public PostService(PostRepository postRepository,
                        UserRepository userRepository,
                        CategoryRepository categoryRepository,
                        TagRepository tagRepository,
+                       LotteryPostRepository lotteryPostRepository,
                        NotificationService notificationService,
                        SubscriptionService subscriptionService,
                        CommentService commentService,
@@ -59,11 +74,14 @@ public class PostService {
                        NotificationRepository notificationRepository,
                        PostReadService postReadService,
                        ImageUploader imageUploader,
+                       TaskScheduler taskScheduler,
+                       EmailSender emailSender,
                        @Value("${app.post.publish-mode:DIRECT}") PublishMode publishMode) {
         this.postRepository = postRepository;
         this.userRepository = userRepository;
         this.categoryRepository = categoryRepository;
         this.tagRepository = tagRepository;
+        this.lotteryPostRepository = lotteryPostRepository;
         this.notificationService = notificationService;
         this.subscriptionService = subscriptionService;
         this.commentService = commentService;
@@ -73,6 +91,8 @@ public class PostService {
         this.notificationRepository = notificationRepository;
         this.postReadService = postReadService;
         this.imageUploader = imageUploader;
+        this.taskScheduler = taskScheduler;
+        this.emailSender = emailSender;
         this.publishMode = publishMode;
     }
 
@@ -88,7 +108,13 @@ public class PostService {
                            Long categoryId,
                            String title,
                            String content,
-                           java.util.List<Long> tagIds) {
+                           java.util.List<Long> tagIds,
+                           PostType type,
+                           String prizeDescription,
+                           String prizeIcon,
+                           Integer prizeCount,
+                           LocalDateTime startTime,
+                           LocalDateTime endTime) {
         long recent = postRepository.countByAuthorAfter(username,
                 java.time.LocalDateTime.now().minusMinutes(5));
         if (recent >= 1) {
@@ -108,14 +134,31 @@ public class PostService {
         if (tags.isEmpty()) {
             throw new IllegalArgumentException("Tag not found");
         }
-        Post post = new Post();
+        PostType actualType = type != null ? type : PostType.NORMAL;
+        Post post;
+        if (actualType == PostType.LOTTERY) {
+            LotteryPost lp = new LotteryPost();
+            lp.setPrizeDescription(prizeDescription);
+            lp.setPrizeIcon(prizeIcon);
+            lp.setPrizeCount(prizeCount != null ? prizeCount : 0);
+            lp.setStartTime(startTime);
+            lp.setEndTime(endTime);
+            post = lp;
+        } else {
+            post = new Post();
+        }
+        post.setType(actualType);
         post.setTitle(title);
         post.setContent(content);
         post.setAuthor(author);
         post.setCategory(category);
-        post.setTags(new java.util.HashSet<>(tags));
+        post.setTags(new HashSet<>(tags));
         post.setStatus(publishMode == PublishMode.REVIEW ? PostStatus.PENDING : PostStatus.PUBLISHED);
-        post = postRepository.save(post);
+        if (post instanceof LotteryPost) {
+            post = lotteryPostRepository.save((LotteryPost) post);
+        } else {
+            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);
@@ -141,9 +184,42 @@ public class PostService {
             }
         }
         notificationService.notifyMentions(content, author, post, null);
+
+        if (post instanceof LotteryPost lp && lp.getEndTime() != null) {
+            taskScheduler.schedule(() -> finalizeLottery(lp.getId()),
+                    java.util.Date.from(lp.getEndTime().atZone(ZoneId.systemDefault()).toInstant()));
+        }
         return post;
     }
 
+    public void joinLottery(Long postId, String username) {
+        LotteryPost post = lotteryPostRepository.findById(postId)
+                .orElseThrow(() -> new com.openisle.exception.NotFoundException("Post not found"));
+        User user = userRepository.findByUsername(username)
+                .orElseThrow(() -> new com.openisle.exception.NotFoundException("User not found"));
+        post.getParticipants().add(user);
+        lotteryPostRepository.save(post);
+    }
+
+    private void finalizeLottery(Long postId) {
+        lotteryPostRepository.findById(postId).ifPresent(lp -> {
+            List<User> participants = new ArrayList<>(lp.getParticipants());
+            if (participants.isEmpty()) {
+                return;
+            }
+            Collections.shuffle(participants);
+            int winnersCount = Math.min(lp.getPrizeCount(), participants.size());
+            java.util.Set<User> winners = new java.util.HashSet<>(participants.subList(0, winnersCount));
+            lp.setWinners(winners);
+            lotteryPostRepository.save(lp);
+            for (User w : winners) {
+                if (w.getEmail() != null) {
+                    emailSender.sendEmail(w.getEmail(), "你中奖了", "恭喜你在抽奖贴 \"" + lp.getTitle() + "\" 中获奖");
+                }
+            }
+        });
+    }
+
     @Transactional
     public Post viewPost(Long id, String viewer) {
         Post post = postRepository.findById(id)