refactor: 패키지 구조 및 코드 스타일 개선

.rules/checkstyle-rules.xml

@@ -356,7 +356,13 @@ The following rules in the Naver coding convention cannot be checked by this con
                      value="[space-after-comma-semicolon]: ''{0}'' is not followed by whitespace."/>
         </module>
         <module name="NoWhitespaceBefore">
-            <property name="tokens" value="COMMA,SEMI"/>
+            <property name="tokens" value="COMMA"/>
+            <message key="ws.preceded"
+                     value="[space-after-comma-semicolon] ''{0}'' is preceded with whitespace."/>
+        </module>
+        <module name="NoWhitespaceBefore">
+            <property name="tokens" value="SEMI"/>
+            <property name="allowLineBreaks" value="true"/>
             <message key="ws.preceded"
                      value="[space-after-comma-semicolon] ''{0}'' is preceded with whitespace."/>
         </module>

src/main/java/queuing/core/CoreApplication.java

@@ -7,9 +7,7 @@
 @SpringBootApplication
 @ConfigurationPropertiesScan
 public class CoreApplication {
-
-	public static void main(String[] args) {
-		SpringApplication.run(CoreApplication.class, args);
-	}
-
+    public static void main(String[] args) {
+        SpringApplication.run(CoreApplication.class, args);
+    }
 }

src/main/java/queuing/core/friend/application/query/GetFriendListQuery.java

@@ -0,0 +1,8 @@
+package queuing.core.friend.application.query;
+
+public record GetFriendListQuery(
+    String userSlug,
+    Long lastId,
+    int size
+) {
+}

src/main/java/queuing/core/friend/application/dto/FriendSummary.java → src/main/java/queuing/core/friend/application/result/FriendSummary.java

@@ -1,4 +1,4 @@
-package queuing.core.friend.application.dto;
+package queuing.core.friend.application.result;
 
 import queuing.core.user.domain.entity.User;
 

src/main/java/queuing/core/friend/application/service/FriendReadService.java

@@ -6,8 +6,9 @@
 import org.springframework.transaction.annotation.Transactional;
 
 import lombok.RequiredArgsConstructor;
-import queuing.core.friend.application.dto.FriendSummary;
-import queuing.core.friend.application.dto.GetFriendListCommand;
+
+import queuing.core.friend.application.query.GetFriendListQuery;
+import queuing.core.friend.application.result.FriendSummary;
 import queuing.core.friend.application.usecase.GetFriendListUseCase;
 import queuing.core.friend.domain.entity.Friend;
 import queuing.core.friend.domain.repository.FriendRepository;
@@ -21,21 +22,24 @@
 @RequiredArgsConstructor
 @Transactional(readOnly = true)
 public class FriendReadService implements GetFriendListUseCase {
-
-    private final UserRepository userRepository;
     private final FriendRepository friendRepository;
+    private final UserRepository userRepository;
 
     @Override
-    public SliceResult<FriendSummary> getFriendList(GetFriendListCommand command) {
-        User user = userRepository.findBySlug(command.userSlug())
+    public SliceResult<FriendSummary> getFriendList(GetFriendListQuery query) {
+        User user = userRepository.findBySlug(query.userSlug())
             .orElseThrow(() -> new BusinessException(ErrorCode.USER_NOT_FOUND));
 
-        SliceResult<Friend> friends = friendRepository.findFriendsByUserId(user.getId(), command.lastId(), command.size());
+        SliceResult<Friend> result = friendRepository.findFriendsByUserId(
+            user.getId(),
+            query.lastId(),
+            query.size()
+        );
 
-        List<FriendSummary> summaries = friends.items().stream()
+        List<FriendSummary> summaries = result.items().stream()
             .map(friend -> FriendSummary.from(friend.getCounterpart(user)))
             .toList();
 
-        return SliceResult.of(summaries, friends.hasNext());
+        return SliceResult.of(summaries, result.hasNext());
     }
-}
+}

src/main/java/queuing/core/friend/application/service/FriendWriteService.java

@@ -32,19 +32,11 @@ public void sendRequest(String requesterSlug, String targetSlug) {
         User target = userRepository.findBySlug(targetSlug)
             .orElseThrow(() -> new BusinessException(ErrorCode.USER_NOT_FOUND));
 
-        if (requester.equals(target)) {
-            throw new BusinessException(ErrorCode.FRIEND_INVALID_REQUEST);
-        }
-
         if (friendRepository.findRelationship(requester, target).isPresent()) {
             throw new BusinessException(ErrorCode.FRIEND_ALREADY_EXISTS);
         }
 
-        Friend friend = Friend.builder()
-            .requester(requester)
-            .receiver(target)
-            .status(FriendStatus.PENDING)
-            .build();
+        Friend friend = Friend.createRequest(requester, target);
 
         friendRepository.save(friend);
     }
@@ -58,15 +50,7 @@ public void acceptRequest(String userSlug, Long requestId) {
         Friend friend = friendRepository.findById(requestId)
             .orElseThrow(() -> new BusinessException(ErrorCode.FRIEND_REQUEST_NOT_FOUND));
 
-        if (!friend.getReceiver().equals(user)) {
-            throw new BusinessException(ErrorCode.FRIEND_INVALID_REQUEST);
-        }
-
-        if (friend.getStatus() != FriendStatus.PENDING) {
-            throw new BusinessException(ErrorCode.FRIEND_INVALID_REQUEST);
-        }
-
-        friend.updateStatus(FriendStatus.ACCEPTED);
+        friend.accept(user);
     }
 
     @Override

src/main/java/queuing/core/friend/application/usecase/DeleteFriendUseCase.java

@@ -2,4 +2,4 @@
 
 public interface DeleteFriendUseCase {
     void deleteFriend(String userSlug, String targetSlug);
-}
+}

src/main/java/queuing/core/friend/application/usecase/GetFriendListUseCase.java

@@ -1,9 +1,9 @@
 package queuing.core.friend.application.usecase;
 
-import queuing.core.friend.application.dto.FriendSummary;
-import queuing.core.friend.application.dto.GetFriendListCommand;
+import queuing.core.friend.application.query.GetFriendListQuery;
+import queuing.core.friend.application.result.FriendSummary;
 import queuing.core.global.dto.SliceResult;
 
 public interface GetFriendListUseCase {
-    SliceResult<FriendSummary> getFriendList(GetFriendListCommand command);
-}
+    SliceResult<FriendSummary> getFriendList(GetFriendListQuery query);
+}

src/main/java/queuing/core/friend/application/usecase/SendFriendRequestUseCase.java

@@ -2,4 +2,4 @@
 
 public interface SendFriendRequestUseCase {
     void sendRequest(String requesterSlug, String targetSlug);
-}
+}

src/main/java/queuing/core/friend/domain/entity/Friend.java

@@ -24,6 +24,9 @@
 import lombok.Builder;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
+
+import queuing.core.global.exception.BusinessException;
+import queuing.core.global.exception.ErrorCode;
 import queuing.core.user.domain.entity.User;
 
 @Entity
@@ -76,4 +79,27 @@ public User getCounterpart(User user) {
         }
         return requester;
     }
+
+    public static Friend createRequest(User requester, User receiver) {
+        if (requester.equals(receiver)) {
+            throw new BusinessException(ErrorCode.FRIEND_INVALID_REQUEST);
+        }
+        return Friend.builder()
+            .requester(requester)
+            .receiver(receiver)
+            .status(FriendStatus.PENDING)
+            .build();
+    }
+
+    public void accept(User user) {
+        if (!this.receiver.equals(user)) {
+            throw new BusinessException(ErrorCode.FRIEND_INVALID_REQUEST);
+        }
+
+        if (this.status != FriendStatus.PENDING) {
+            throw new BusinessException(ErrorCode.FRIEND_INVALID_REQUEST);
+        }
+
+        this.status = FriendStatus.ACCEPTED;
+    }
 }

src/main/java/queuing/core/friend/domain/repository/FriendRepository.java

@@ -18,10 +18,9 @@ public interface FriendRepository extends JpaRepository<Friend, Long>, FriendRep
 
     Optional<Friend> findByRequesterAndReceiver(User requester, User receiver);
 
-    // Find a relationship in either direction
-    @Query("SELECT f FROM Friend f WHERE (f.requester = :user1 AND f.receiver = :user2) OR (f.requester = :user2 AND f.receiver = :user1)")
+    @Query("SELECT f FROM Friend f WHERE (f.requester = :user1 AND f.receiver = :user2) "
+        + "OR (f.requester = :user2 AND f.receiver = :user1)")
     Optional<Friend> findRelationship(@Param("user1") User user1, @Param("user2") User user2);
 
-    // Find pending requests received by user
     Page<Friend> findByReceiverAndStatus(User receiver, FriendStatus status, Pageable pageable);
 }

src/main/java/queuing/core/friend/infrastructure/querydsl/FriendRepositoryImpl.java

@@ -8,6 +8,7 @@
 import com.querydsl.jpa.impl.JPAQueryFactory;
 
 import lombok.RequiredArgsConstructor;
+
 import queuing.core.friend.domain.entity.Friend;
 import queuing.core.friend.domain.entity.FriendStatus;
 import queuing.core.friend.domain.entity.QFriend;
@@ -25,7 +26,7 @@ public SliceResult<Friend> findFriendsByUserId(Long userId, Long lastId, int siz
 
         BooleanExpression isFriend = (friend.requester.id.eq(userId).or(friend.receiver.id.eq(userId)))
             .and(friend.status.eq(FriendStatus.ACCEPTED));
-        
+
         BooleanExpression lessThanId = (lastId != null) ? friend.id.lt(lastId) : null;
 
         List<Friend> friends = query.selectFrom(friend)
@@ -44,4 +45,4 @@ public SliceResult<Friend> findFriendsByUserId(Long userId, Long lastId, int siz
 
         return SliceResult.of(friends, hasNext);
     }
-}
+}

src/main/java/queuing/core/friend/presentation/controller/FriendController.java

@@ -14,8 +14,8 @@
 
 import lombok.RequiredArgsConstructor;
 
-import queuing.core.friend.application.dto.FriendSummary;
-import queuing.core.friend.application.dto.GetFriendListCommand;
+import queuing.core.friend.application.query.GetFriendListQuery;
+import queuing.core.friend.application.result.FriendSummary;
 import queuing.core.friend.application.usecase.DeleteFriendUseCase;
 import queuing.core.friend.application.usecase.GetFriendListUseCase;
 import queuing.core.friend.presentation.response.FriendResponse;
@@ -50,7 +50,7 @@ public ResponseEntity<ResponseBody<ListFriendResponse>> getFriends(
         @RequestParam(defaultValue = "20") int size
     ) {
         SliceResult<FriendSummary> result = getFriendListUseCase.getFriendList(
-            new GetFriendListCommand(principal.getUsername(), lastId, size)
+            new GetFriendListQuery(principal.getUsername(), lastId, size)
         );
 
         List<FriendResponse> items = result.items().stream()

src/main/java/queuing/core/friend/presentation/request/SendFriendRequest.java

@@ -5,4 +5,5 @@
 public record SendFriendRequest(
     @NotBlank(message = "친구 추가할 대상을 입력해주세요.")
     String targetSlug
-) {}
+) {
+}

src/main/java/queuing/core/friend/presentation/response/FriendResponse.java

@@ -1,6 +1,6 @@
 package queuing.core.friend.presentation.response;
 
-import queuing.core.friend.application.dto.FriendSummary;
+import queuing.core.friend.application.result.FriendSummary;
 
 public record FriendResponse(
     Long id,

src/main/java/queuing/core/global/dto/PageCondition.java

@@ -0,0 +1,55 @@
+package queuing.core.global.dto;
+
+/**
+ * 페이징 조회를 위한 요청 조건을 담습니다.
+ *
+ * @param page 현재 페이지 번호 (1부터 시작)
+ * @param size 한 페이지당 보여줄 아이템 개수
+ * @param sort 정렬 조건
+ */
+public record PageCondition(
+    int page,
+    int size,
+    String sort
+) {
+    public PageCondition {
+        if (page < 1) {
+            throw new IllegalArgumentException("Page number must be 1 or greater.");
+        }
+        if (size < 1) {
+            throw new IllegalArgumentException("Page size must be 1 or greater.");
+        }
+    }
+
+    /**
+     * 정렬 조건 없는 {@code PageCondition} 객체를 생성합니다.
+     *
+     * @param page 현재 페이지 번호 (1부터 시작)
+     * @param size 한 페이지당 보여줄 아이템 개수
+     * @return PageCondition 객체
+     */
+    public static PageCondition of(int page, int size) {
+        return new PageCondition(page, size, null);
+    }
+
+    /**
+     * 정렬 조건이 있는 {@code PageCondition} 객체를 생성합니다.
+     *
+     * @param page 현재 페이지 번호 (1부터 시작)
+     * @param size 한 페이지당 보여줄 아이템 개수
+     * @param sort 정렬 조건
+     * @return PageCondition 객체
+     */
+    public static PageCondition of(int page, int size, String sort) {
+        return new PageCondition(page, size, sort);
+    }
+
+    /**
+     * 데이터베이스 조회 시작 지점을 반환합니다.
+
+     * @return offset
+     */
+    public long offset() {
+        return (long) (page - 1) * size;
+    }
+}