#16 board: hashtag service implementation

board/src/main/java/com/example/board/service/ArticleService.java

@@ -1,11 +1,13 @@
 package com.example.board.service;
 
 import com.example.board.domain.Article;
+import com.example.board.domain.Hashtag;
 import com.example.board.domain.UserAccount;
 import com.example.board.domain.constant.SearchType;
 import com.example.board.dto.ArticleDto;
 import com.example.board.dto.ArticleWithCommentsDto;
 import com.example.board.repository.ArticleRepository;
+import com.example.board.repository.HashtagRepository;
 import com.example.board.repository.UserAccountRepository;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -17,6 +19,8 @@ import org.springframework.transaction.annotation.Transactional;
 import javax.persistence.EntityNotFoundException;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 @Slf4j
 @RequiredArgsConstructor
@@ -24,6 +28,8 @@ import java.util.List;
 @Service
 public class ArticleService {
 
+    private final HashtagService hashtagService;
+    private final HashtagRepository hashtagRepository;
     private final ArticleRepository articleRepository;
     private final UserAccountRepository userAccountRepository;
 
@@ -62,7 +68,28 @@ public class ArticleService {
 
     public void saveArticle(ArticleDto dto) {
         UserAccount userAccount = userAccountRepository.getReferenceById(dto.userAccountDto().userId());
-        articleRepository.save(dto.toEntity(userAccount));
+        Set<Hashtag> hashtags = renewHashtagsFromContent(dto.content());
+
+        Article article = dto.toEntity(userAccount);
+        article.addHashtags(hashtags);
+
+        articleRepository.save(article);
+    }
+
+    private Set<Hashtag> renewHashtagsFromContent(String content) {
+        Set<String> hashtagNamesInContent = hashtagService.parseHashtagNames(content);
+        Set<Hashtag> hashtags = hashtagService.findHashtagsByNames(hashtagNamesInContent);
+        Set<String> existingHashtagNames = hashtags.stream()
+                .map(Hashtag::getHashtagName)
+                .collect(Collectors.toUnmodifiableSet());
+
+        hashtagNamesInContent.forEach(newHashtagName -> {
+            if (!existingHashtagNames.contains(newHashtagName)) {
+                hashtags.add(Hashtag.of(newHashtagName));
+            }
+        });
+
+        return hashtags;
     }
 
     public void updateArticle(Long articleId, ArticleDto dto) {
@@ -73,6 +100,18 @@ public class ArticleService {
             if (article.getUserAccount().equals(userAccount)) {
                 if (dto.title() != null) { article.setTitle(dto.title()); }
                 if (dto.content() != null) { article.setContent(dto.content()); }
+
+                Set<Long> hashtagIds = article.getHashtags().stream()
+                        .map(Hashtag::getId)
+                        .collect(Collectors.toUnmodifiableSet());
+
+                article.clearHashtags();
+                articleRepository.flush();
+
+                hashtagIds.forEach(hashtagService::deleteHashtagWithoutArticles);
+
+                Set<Hashtag> hashtags = renewHashtagsFromContent(dto.content());
+                article.addHashtags(hashtags);
             }
         } catch (EntityNotFoundException e) {
             log.warn("게시글 업데이트 실패. 게시글을 수정하는데 필요한 정보를 찾을 수 없습니다 - {}", e.getLocalizedMessage());
@@ -80,7 +119,15 @@ public class ArticleService {
     }
 
     public void deleteArticle(long articleId, String userId) {
+        Article article = articleRepository.getReferenceById(articleId);
+        Set<Long> hashtagIds = article.getHashtags().stream()
+                .map(Hashtag::getId)
+                .collect(Collectors.toUnmodifiableSet());
+
         articleRepository.deleteByIdAndUserAccount_UserId(articleId, userId);
+        articleRepository.flush();
+
+        hashtagIds.forEach(hashtagService::deleteHashtagWithoutArticles);
     }
 
     public long getArticleCount() {
@@ -88,16 +135,17 @@ public class ArticleService {
     }
 
     @Transactional(readOnly = true)
-    public Page<ArticleDto> searchArticlesViaHashtag(String hashtag, Pageable pageable) {
-        if (hashtag == null || hashtag.isBlank()) {
+    public Page<ArticleDto> searchArticlesViaHashtag(String hashtagName, Pageable pageable) {
+        if (hashtagName == null || hashtagName.isBlank()) {
             return Page.empty(pageable);
         }
 
-        return articleRepository.findByHashtagNames(null, pageable).map(ArticleDto::from);
+        return articleRepository.findByHashtagNames(List.of(hashtagName), pageable)
+                .map(ArticleDto::from);
     }
 
     public List<String> getHashtags() {
-        return articleRepository.findAllDistinctHashtags();
+        return hashtagRepository.findAllHashtagNames();
     }
 
 }

board/src/main/java/com/example/board/service/HashtagService.java

@@ -1,20 +1,45 @@
 package com.example.board.service;
 
 import com.example.board.domain.Hashtag;
+import com.example.board.repository.HashtagRepository;
+import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
 
+import java.util.HashSet;
 import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 @Service
+@RequiredArgsConstructor
 public class HashtagService {
+
+    private final HashtagRepository hashtagRepository;
+
     public Set<String> parseHashtagNames(String content) {
-        return null;
+        if (content == null) {
+            return Set.of();
+        }
+
+        Pattern pattern = Pattern.compile("#[\\w가-힣]+");
+        Matcher matcher = pattern.matcher(content.strip());
+        Set<String> result = new HashSet<>();
+
+        while (matcher.find()) {
+            result.add(matcher.group().replace("#", ""));
+        }
+
+        return Set.copyOf(result);
     }
 
-    public Set<Hashtag> findHashtagsByNames(Set<String> expectedHashtagNames) {
-        return null;
+    public Set<Hashtag> findHashtagsByNames(Set<String> hashtagNames) {
+        return new HashSet<>(hashtagRepository.findByHashtagNameIn(hashtagNames));
     }
 
-    public void deleteHashtagWithoutArticles(Object any) {
+    public void deleteHashtagWithoutArticles(Long hashtagId) {
+        Hashtag hashtag = hashtagRepository.getReferenceById(hashtagId);
+        if (hashtag.getArticles().isEmpty()) {
+            hashtagRepository.delete(hashtag);
+        }
     }
 }

board/src/test/java/com/example/board/service/HashtagServiceTest.java

@@ -8,7 +8,6 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
-import org.mockito.BDDMockito;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
@@ -17,9 +16,10 @@ import java.util.List;
 import java.util.Set;
 import java.util.stream.Stream;
 
-import static org.assertj.core.api.Assertions.*;
-import static org.junit.jupiter.params.provider.Arguments.*;
-import static org.mockito.BDDMockito.*;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.params.provider.Arguments.arguments;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.BDDMockito.then;
 
 @DisplayName("비즈니스 로직 - 해시태그")
 @ExtendWith(MockitoExtension.class)