feat: 북마크 서비스를 생성하라.

src/main/java/com/developer/wiki/bookmark/BookmarkController.java

@@ -11,7 +11,7 @@
 
 @RequiredArgsConstructor
 @RestController
-@RequestMapping("/api/v1/bookmarka")
+@RequestMapping("/api/v1/bookmarks")
 public class BookmarkController {
 
   private final BookmarkService bookmarkService;

src/main/java/com/developer/wiki/bookmark/BookmarkService.java

@@ -1,5 +1,38 @@
-package com.developer.wiki.oauth.service;
+package com.developer.wiki.bookmark;
 
+import com.developer.wiki.common.exception.NotFoundException;
+import com.developer.wiki.oauth.UserRepository;
+import com.developer.wiki.question.command.domain.Question;
+import com.developer.wiki.question.command.domain.QuestionRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@Transactional
+@RequiredArgsConstructor
 public class BookmarkService {
 
+  private final QuestionRepository questionRepository;
+  private final UserRepository userRepository;
+  private final BookmarkRepository bookmarkRepository;
+
+  public void toggle(Long questionId, Long userId) {
+    Question question = questionRepository.findById(questionId)
+        .orElseThrow(() -> new NotFoundException("존재하지 않는 ID입니다."));
+    bookmarkRepository.findByUserIdAndQuestion(userId, question).ifPresentOrElse(bookmark -> {
+      unBookmark(bookmark);
+    }, () -> {
+      bookmark(userId, question);
+    });
+  }
+
+  private void bookmark(Long userId, Question question) {
+    Bookmark bookmark = new Bookmark(userId, question);
+    bookmarkRepository.save(bookmark);
+  }
+
+  private void unBookmark(Bookmark bookmark) {
+    bookmarkRepository.delete(bookmark);
+  }
 }