[Feature] 팔로잉, 팔로워 목록 조회를 구현한다 (#28)

* feature: NoOffset 구현을 위한 VO 클래스, 유틸 추가

* fix: LongIdList, PageArgumentResolver에 예외 상황 추가

* feature: ProfileService 도메인 서비스 작성

* feature: 팔로잉, 팔로워 조회 구현

* feature: 팔로워 삭제 구현

src/main/java/daybyquest/global/config/WebMvcConfig.java

@@ -2,6 +2,7 @@
 
 import daybyquest.auth.AuthorizationInterceptor;
 import daybyquest.auth.UserIdArgumentResolver;
+import daybyquest.global.query.NoOffsetIdPageArgumentResolver;
 import java.util.List;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
@@ -19,5 +20,6 @@ public void addInterceptors(final InterceptorRegistry registry) {
     @Override
     public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
         resolvers.add(new UserIdArgumentResolver());
+        resolvers.add(new NoOffsetIdPageArgumentResolver());
     }
 }

src/main/java/daybyquest/global/error/ExceptionCode.java

@@ -63,7 +63,7 @@ public enum ExceptionCode {
     NOT_EXIST_INTEREST("INT-00", BAD_REQUEST, "존재하지 않는 관심사 입니다"),
 
     // Relationship
-    NOT_FOLLOWING_USER("REL-00", BAD_REQUEST, "팔로우하지 않은 사용자는 취소할 수 없습니다"),
+    NOT_FOLLOWING_USER("REL-00", BAD_REQUEST, "팔로우하지 않은 사용자입니다"),
     NOT_BLOCKING_USER("REL-01", BAD_REQUEST, "차단하지 않은 사용자는 취소할 수 없습니다"),
     ALREADY_FOLLOWING_USER("REL-02", BAD_REQUEST, "이미 팔로우한 사용자입니다"),
     ALREADY_BLOCKING_USER("REL-03", BAD_REQUEST, "이미 차단한 사용자입니다"),

src/main/java/daybyquest/global/error/exception/BadRequestException.java

@@ -3,7 +3,11 @@
 import daybyquest.global.error.ExceptionCode;
 import java.util.List;
 
-public class BadRequestException extends CustomException{
+public class BadRequestException extends CustomException {
+
+    public BadRequestException() {
+        super(ExceptionCode.INVALID_REQUEST);
+    }
 
     public BadRequestException(ExceptionCode exceptionCode, List<String> fields) {
         super(exceptionCode, fields);

src/main/java/daybyquest/global/query/LongIdList.java

@@ -0,0 +1,21 @@
+package daybyquest.global.query;
+
+import java.util.List;
+import lombok.Getter;
+
+@Getter
+public class LongIdList {
+
+    private final List<Long> ids;
+
+    public LongIdList(final List<Long> ids) {
+        this.ids = ids;
+    }
+
+    public Long getLastId() {
+        if (ids.isEmpty()) {
+            return Long.MAX_VALUE;
+        }
+        return ids.get(ids.size() - 1);
+    }
+}

src/main/java/daybyquest/global/query/NoOffsetIdPage.java

@@ -0,0 +1,16 @@
+package daybyquest.global.query;
+
+import lombok.Getter;
+
+@Getter
+public class NoOffsetIdPage {
+
+    private final Long lastId;
+
+    private final int limit;
+
+    public NoOffsetIdPage(final Long lastId, final int limit) {
+        this.lastId = lastId;
+        this.limit = limit;
+    }
+}

src/main/java/daybyquest/global/query/NoOffsetIdPageArgumentResolver.java

@@ -0,0 +1,52 @@
+package daybyquest.global.query;
+
+import daybyquest.global.error.exception.BadRequestException;
+import jakarta.annotation.Nonnull;
+import java.util.regex.Pattern;
+import org.springframework.core.MethodParameter;
+import org.springframework.web.bind.support.WebDataBinderFactory;
+import org.springframework.web.context.request.NativeWebRequest;
+import org.springframework.web.method.support.HandlerMethodArgumentResolver;
+import org.springframework.web.method.support.ModelAndViewContainer;
+
+public class NoOffsetIdPageArgumentResolver implements HandlerMethodArgumentResolver {
+
+    private static final int MAX_LIMIT = 15;
+    private static final Pattern NUMBER = Pattern.compile("^[0-9]*$");
+
+
+    @Override
+    public boolean supportsParameter(MethodParameter parameter) {
+        return parameter.getParameterType().equals(NoOffsetIdPage.class);
+    }
+
+    @Override
+    public Object resolveArgument(@Nonnull MethodParameter parameter, ModelAndViewContainer mavContainer,
+            @Nonnull NativeWebRequest webRequest, WebDataBinderFactory binderFactory) {
+        final String lastIdArgument = webRequest.getParameter("lastId");
+        final String limitArgument = webRequest.getParameter("limit");
+        return new NoOffsetIdPage(convertAndValidateLastId(lastIdArgument),
+                convertAndValidateLimit(limitArgument));
+    }
+
+    private Long convertAndValidateLastId(String lastId) {
+        if (lastId == null) {
+            return 0L;
+        }
+        if (!NUMBER.matcher(lastId).matches()) {
+            throw new BadRequestException();
+        }
+        return Long.parseLong(lastId);
+    }
+
+    private int convertAndValidateLimit(String limit) {
+        if (limit == null || !NUMBER.matcher(limit).matches()) {
+            throw new BadRequestException();
+        }
+        final int parsedLimit = Integer.parseInt(limit);
+        if (parsedLimit > MAX_LIMIT) {
+            throw new BadRequestException();
+        }
+        return parsedLimit;
+    }
+}

src/main/java/daybyquest/relation/application/DeleteFollowerService.java

@@ -0,0 +1,25 @@
+package daybyquest.relation.application;
+
+import daybyquest.relation.domain.Follow;
+import daybyquest.relation.domain.Follows;
+import daybyquest.user.domain.Users;
+import org.springframework.stereotype.Service;
+
+@Service
+public class DeleteFollowerService {
+
+    private final Follows follows;
+
+    private final Users users;
+
+    public DeleteFollowerService(final Follows follows, final Users users) {
+        this.follows = follows;
+        this.users = users;
+    }
+
+    public void invoke(final Long loginId, final String targetUsername) {
+        final Long targetId = users.getUserIdByUsername(targetUsername);
+        final Follow follow = follows.getByUserIdAndTargetId(targetId, loginId);
+        follows.delete(follow);
+    }
+}

src/main/java/daybyquest/relation/application/GetFollowersService.java

@@ -0,0 +1,31 @@
+package daybyquest.relation.application;
+
+import daybyquest.global.query.LongIdList;
+import daybyquest.global.query.NoOffsetIdPage;
+import daybyquest.relation.query.FollowDao;
+import daybyquest.user.dto.response.PageProfilesResponse;
+import daybyquest.user.dto.response.ProfileResponse;
+import daybyquest.user.query.ProfileService;
+import java.util.List;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+public class GetFollowersService {
+
+    private final FollowDao followDao;
+
+    private final ProfileService profileService;
+
+    public GetFollowersService(final FollowDao followDao, final ProfileService profileService) {
+        this.followDao = followDao;
+        this.profileService = profileService;
+    }
+
+    @Transactional(readOnly = true)
+    public PageProfilesResponse invoke(final Long loginId, final NoOffsetIdPage page) {
+        final LongIdList targetIds = followDao.getFollowerIds(loginId, page);
+        final List<ProfileResponse> profiles = profileService.getProfilesByIdIn(loginId, targetIds.getIds());
+        return new PageProfilesResponse(profiles, targetIds.getLastId());
+    }
+}

src/main/java/daybyquest/relation/application/GetFollowingsService.java

@@ -0,0 +1,31 @@
+package daybyquest.relation.application;
+
+import daybyquest.global.query.LongIdList;
+import daybyquest.global.query.NoOffsetIdPage;
+import daybyquest.relation.query.FollowDao;
+import daybyquest.user.dto.response.PageProfilesResponse;
+import daybyquest.user.dto.response.ProfileResponse;
+import daybyquest.user.query.ProfileService;
+import java.util.List;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+public class GetFollowingsService {
+
+    private final FollowDao followDao;
+
+    private final ProfileService profileService;
+
+    public GetFollowingsService(final FollowDao followDao, final ProfileService profileService) {
+        this.followDao = followDao;
+        this.profileService = profileService;
+    }
+
+    @Transactional(readOnly = true)
+    public PageProfilesResponse invoke(final Long loginId, final NoOffsetIdPage page) {
+        final LongIdList targetIds = followDao.getFollowingIds(loginId, page);
+        final List<ProfileResponse> profiles = profileService.getProfilesByIdIn(loginId, targetIds.getIds());
+        return new PageProfilesResponse(profiles, targetIds.getLastId());
+    }
+}

src/main/java/daybyquest/relation/presentation/FollowController.java

@@ -2,10 +2,16 @@
 
 import daybyquest.auth.Authorization;
 import daybyquest.auth.UserId;
+import daybyquest.global.query.NoOffsetIdPage;
 import daybyquest.relation.application.DeleteFollowService;
+import daybyquest.relation.application.DeleteFollowerService;
+import daybyquest.relation.application.GetFollowersService;
+import daybyquest.relation.application.GetFollowingsService;
 import daybyquest.relation.application.SaveFollowService;
+import daybyquest.user.dto.response.PageProfilesResponse;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RestController;
@@ -17,10 +23,20 @@ public class FollowController {
 
     private final DeleteFollowService deleteFollowService;
 
+    private final DeleteFollowerService deleteFollowerService;
+
+    private final GetFollowersService getFollowersService;
+
+    private final GetFollowingsService getFollowingsService;
+
     public FollowController(final SaveFollowService saveFollowService,
-            final DeleteFollowService deleteFollowService) {
+            final DeleteFollowService deleteFollowService, final DeleteFollowerService deleteFollowerService,
+            final GetFollowersService getFollowersService, final GetFollowingsService getFollowingsService) {
         this.saveFollowService = saveFollowService;
         this.deleteFollowService = deleteFollowService;
+        this.deleteFollowerService = deleteFollowerService;
+        this.getFollowersService = getFollowersService;
+        this.getFollowingsService = getFollowingsService;
     }
 
     @PostMapping("/profile/{username}/follow")
@@ -38,4 +54,28 @@ public ResponseEntity<Void> deleteFollow(@UserId final Long loginId,
         deleteFollowService.invoke(loginId, username);
         return ResponseEntity.ok().build();
     }
+
+    @DeleteMapping("/profile/{username}/follower")
+    @Authorization
+    public ResponseEntity<Void> deleteFollower(@UserId final Long loginId,
+            @PathVariable final String username) {
+        deleteFollowerService.invoke(loginId, username);
+        return ResponseEntity.ok().build();
+    }
+
+    @GetMapping("/followings")
+    @Authorization
+    public ResponseEntity<PageProfilesResponse> getFollowings(@UserId final Long loginId,
+            final NoOffsetIdPage page) {
+        final PageProfilesResponse response = getFollowingsService.invoke(loginId, page);
+        return ResponseEntity.ok(response);
+    }
+
+    @GetMapping("/followers")
+    @Authorization
+    public ResponseEntity<PageProfilesResponse> getFollowers(@UserId final Long loginId,
+            final NoOffsetIdPage page) {
+        final PageProfilesResponse response = getFollowersService.invoke(loginId, page);
+        return ResponseEntity.ok(response);
+    }
 }

src/main/java/daybyquest/relation/query/FollowDao.java

@@ -0,0 +1,11 @@
+package daybyquest.relation.query;
+
+import daybyquest.global.query.LongIdList;
+import daybyquest.global.query.NoOffsetIdPage;
+
+public interface FollowDao {
+
+    LongIdList getFollowingIds(final Long userId, final NoOffsetIdPage page);
+
+    LongIdList getFollowerIds(final Long targetId, final NoOffsetIdPage page);
+}

src/main/java/daybyquest/relation/query/FollowDaoQuerydslImpl.java

@@ -0,0 +1,36 @@
+package daybyquest.relation.query;
+
+import static daybyquest.relation.domain.QFollow.follow;
+
+import com.querydsl.jpa.impl.JPAQueryFactory;
+import daybyquest.global.query.LongIdList;
+import daybyquest.global.query.NoOffsetIdPage;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public class FollowDaoQuerydslImpl implements FollowDao {
+
+    private final JPAQueryFactory factory;
+
+    public FollowDaoQuerydslImpl(final JPAQueryFactory factory) {
+        this.factory = factory;
+    }
+
+    @Override
+    public LongIdList getFollowingIds(final Long userId, final NoOffsetIdPage page) {
+        return new LongIdList(factory.select(follow.targetId)
+                .from(follow)
+                .where(follow.userId.eq(userId).and(follow.targetId.gt(page.getLastId())))
+                .limit(page.getLimit())
+                .fetch());
+    }
+
+    @Override
+    public LongIdList getFollowerIds(final Long targetId, final NoOffsetIdPage page) {
+        return new LongIdList(factory.select(follow.userId)
+                .from(follow)
+                .where(follow.targetId.eq(targetId).and(follow.userId.gt(page.getLastId())))
+                .limit(page.getLimit())
+                .fetch());
+    }
+}

src/main/java/daybyquest/user/dto/response/PageProfilesResponse.java

@@ -0,0 +1,19 @@
+package daybyquest.user.dto.response;
+
+import java.util.List;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Getter
+@NoArgsConstructor
+public class PageProfilesResponse {
+
+    private List<ProfileResponse> users;
+
+    private Long nextId;
+
+    public PageProfilesResponse(final List<ProfileResponse> users, final Long nextId) {
+        this.users = users;
+        this.nextId = nextId;
+    }
+}

src/main/java/daybyquest/user/query/ProfileDao.java

@@ -1,10 +1,14 @@
 package daybyquest.user.query;
 
 import daybyquest.user.domain.Profile;
+import java.util.Collection;
+import java.util.List;
 
 public interface ProfileDao {
 
     Profile getByUsername(final Long userId, final String username);
 
     Profile getMine(final Long userId);
+
+    List<Profile> findAllByUserIdIn(final Long userId, final Collection<Long> targetIds);
 }