[#297][FEAT]모임 멤버 관리 조회

src/main/java/com/dokdok/gathering/api/GatheringApi.java

@@ -5,6 +5,7 @@
 import com.dokdok.gathering.dto.request.GatheringUpdateRequest;
 import com.dokdok.gathering.dto.request.JoinGatheringMemberRequest;
 import com.dokdok.gathering.dto.response.*;
+import com.dokdok.gathering.entity.GatheringMemberStatus;
 import com.dokdok.global.response.ApiResponse;
 import com.dokdok.global.response.CursorResponse;
 import com.dokdok.global.response.PageResponse;
@@ -976,4 +977,107 @@ ResponseEntity<ApiResponse<PageResponse<GatheringBookListResponse>>> getGatherin
             @Parameter(description = "페이지 크기", example = "10")
             @RequestParam(defaultValue = "10") int size
     );
+
+    @Operation(
+            summary = "모임 멤버 목록 조회 (developer: 오주현)",
+            description = """                                                                                                                                                      
+                  모임의 멤버 목록을 상태별로 조회합니다.
+                  - 모임장만 조회할 수 있습니다.
+                  - 커서 기반 무한 스크롤을 지원합니다.
+                  - ID 내림차순으로 정렬됩니다.
+                  - 첫 페이지: cursorId 없이 호출
+                  - 다음 페이지: 응답의 nextCursor.gatheringMemberId 값을 cursorId로 전달
+                  ENUM
+                  - status: PENDING(가입요청), ACTIVE(가입승인)
+                  - role: LEADER(모임장), MEMBER(모임원)
+                  - memberStatus: PENDING(가입요청), ACTIVE(가입승인), REJECTED(가입거절)
+                  """
+    )
+    @ApiResponses({
+            @io.swagger.v3.oas.annotations.responses.ApiResponse(
+                    responseCode = "200",
+                    description = "조회 성공",
+                    content = @Content(
+                            mediaType = MediaType.APPLICATION_JSON_VALUE,
+                            schema = @Schema(implementation = CursorResponse.class),
+                            examples = @ExampleObject(value = """                                                                                                                  
+                                      {
+                                        "code": "SUCCESS",
+                                        "message": "모임 멤버 목록 조회 성공",
+                                        "data": {
+                                          "items": [
+                                            {
+                                              "gatheringMemberId": 10,
+                                              "userId": 1,
+                                              "nickname": "독서왕",
+                                              "profileImageUrl": "https://example.com/profile.jpg",
+                                              "role": "MEMBER",
+                                              "memberStatus": "PENDING",
+                                              "joinedAt": null
+                                            }
+                                          ],
+                                          "pageSize": 10,
+                                          "hasNext": false,
+                                          "nextCursor": null,
+                                          "totalCount": 1
+                                        }
+                                      }
+                                      """)
+                    )
+            ),
+            @io.swagger.v3.oas.annotations.responses.ApiResponse(
+                    responseCode = "401",
+                    description = "인증 실패 - 로그인이 필요합니다.",
+                    content = @Content(
+                            mediaType = MediaType.APPLICATION_JSON_VALUE,
+                            examples = @ExampleObject(value = """                                                                                                                  
+                                      {"code": "G102", "message": "인증이 필요합니다.", "data": null}
+                                      """)
+                    )
+            ),
+            @io.swagger.v3.oas.annotations.responses.ApiResponse(
+                    responseCode = "403",
+                    description = "권한 없음 - 모임장만 조회할 수 있습니다.",
+                    content = @Content(
+                            mediaType = MediaType.APPLICATION_JSON_VALUE,
+                            examples = @ExampleObject(value = """                                                                                                                  
+                                      {"code": "GA003", "message": "리더만 가능한 작업입니다.", "data": null}
+                                      """)
+                    )
+            ),
+            @io.swagger.v3.oas.annotations.responses.ApiResponse(
+                    responseCode = "404",
+                    description = "모임을 찾을 수 없음",
+                    content = @Content(
+                            mediaType = MediaType.APPLICATION_JSON_VALUE,
+                            examples = @ExampleObject(value = """                                                                                                                  
+                                      {"code": "GA001", "message": "모임을 찾을 수 없습니다.", "data": null}
+                                      """)
+                    )
+            ),
+            @io.swagger.v3.oas.annotations.responses.ApiResponse(
+                    responseCode = "500",
+                    description = "서버 오류",
+                    content = @Content(
+                            mediaType = MediaType.APPLICATION_JSON_VALUE,
+                            examples = @ExampleObject(value = """                                                                                                                  
+                                      {"code": "E000", "message": "서버 에러가 발생했습니다. 담당자에게 문의 바랍니다.", "data": null}
+                                      """)
+                    )
+            )
+    })
+    @GetMapping("/{gatheringId}/members")
+    ResponseEntity<ApiResponse<CursorResponse<GatheringMemberResponse, GatheringMemberCursor>>> getGatheringMembers(
+            @Parameter(description = "모임 ID", required = true, example = "1")
+            @PathVariable Long gatheringId,
+
+            @Parameter(description = "멤버 상태 (PENDING: 승인대기, ACTIVE: 승인됨)", required = true, example = "PENDING")
+            @RequestParam GatheringMemberStatus status,
+
+            @Parameter(description = "페이지 크기", example = "10")
+            @RequestParam(defaultValue = "10") int pageSize,
+
+            @Parameter(description = "커서 - 마지막 항목의 모임 멤버 ID", example = "127")
+            @RequestParam(required = false) Long cursorId
+    );
 }

src/main/java/com/dokdok/gathering/controller/GatheringController.java

@@ -5,6 +5,7 @@
 import com.dokdok.gathering.dto.request.JoinGatheringMemberRequest;
 import com.dokdok.gathering.dto.response.*;
 import com.dokdok.gathering.dto.request.GatheringUpdateRequest;
+import com.dokdok.gathering.entity.GatheringMemberStatus;
 import com.dokdok.gathering.service.GatheringService;
 import com.dokdok.global.response.ApiResponse;
 import com.dokdok.global.response.CursorResponse;
@@ -18,7 +19,6 @@
 import org.springframework.web.bind.annotation.*;
 
 import java.time.LocalDateTime;
-import java.util.List;
 
 @RestController
 @RequestMapping("/api/gatherings")
@@ -136,4 +136,16 @@ public ResponseEntity<ApiResponse<PageResponse<GatheringBookListResponse>>> getG
         PageResponse<GatheringBookListResponse> response = gatheringService.getGatheringBooks(gatheringId, page, size);
         return ApiResponse.success(response, "모임 책장 조회를 성공했습니다.");
     }
+
+    @Override
+    @GetMapping("/{gatheringId}/members")
+    public ResponseEntity<ApiResponse<CursorResponse<GatheringMemberResponse, GatheringMemberCursor>>> getGatheringMembers(
+            @PathVariable Long gatheringId,
+            @RequestParam GatheringMemberStatus status,
+            @RequestParam(defaultValue = "10") int pageSize,
+            @RequestParam(required = false) Long cursorId
+    ){
+        CursorResponse<GatheringMemberResponse, GatheringMemberCursor> response = gatheringService.getGatheringMembers(gatheringId, status, pageSize, cursorId);
+        return ApiResponse.success(response,"모임 멤버 관리 조회 성공");
+    }
 }

src/main/java/com/dokdok/gathering/dto/response/GatheringMemberCursor.java

@@ -0,0 +1,14 @@
+package com.dokdok.gathering.dto.response;
+
+import com.dokdok.gathering.entity.GatheringMember;
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@Schema(description = "모임 멤버 관리 커서")
+public record GatheringMemberCursor(
+        @Schema(description = "모임 멤버 ID", example = "10")
+        Long gatheringMemberId
+) {
+    public static GatheringMemberCursor from(GatheringMember member){
+        return new GatheringMemberCursor(member.getId());
+    }
+}

src/main/java/com/dokdok/gathering/dto/response/GatheringMemberResponse.java

@@ -0,0 +1,46 @@
+package com.dokdok.gathering.dto.response;
+
+import com.dokdok.gathering.entity.GatheringMember;
+import com.dokdok.gathering.entity.GatheringMemberStatus;
+import com.dokdok.gathering.entity.GatheringRole;
+import io.swagger.v3.oas.annotations.media.Schema;
+import lombok.Builder;
+
+import java.time.LocalDateTime;
+
+@Schema(description = "모임 멤버 관리 정보")
+@Builder
+public record GatheringMemberResponse(
+        @Schema(description = "모임 멤버 ID", example = "10")
+        Long gatheringMemberId,
+
+        @Schema(description = "사용자 ID", example = "1")
+        Long userId,
+
+        @Schema(description = "닉네임", example = "독서왕")
+        String nickname,
+
+        @Schema(description = "프로필 이미지 URL")
+        String profileImageUrl,
+
+        @Schema(description = "모임 역할", example = "MEMBER")
+        GatheringRole role,
+
+        @Schema(description = "멤버 상태", example = "PENDING")
+        GatheringMemberStatus memberStatus,
+
+        @Schema(description = "가입 승인 일시")
+        LocalDateTime joinedAt
+) {
+    public static GatheringMemberResponse from(GatheringMember member, String  presignedProfileImageUrl) {
+        return GatheringMemberResponse.builder()
+                .gatheringMemberId(member.getId())
+                .userId(member.getUser().getId())
+                .nickname(member.getUser().getNickname())
+                .profileImageUrl(presignedProfileImageUrl)
+                .role(member.getRole())
+                .memberStatus(member.getMemberStatus())
+                .joinedAt(member.getJoinedAt())
+                .build();
+    }
+}

src/main/java/com/dokdok/gathering/repository/GatheringMemberRepository.java

@@ -1,6 +1,7 @@
 package com.dokdok.gathering.repository;
 
 import com.dokdok.gathering.entity.GatheringMember;
+import com.dokdok.gathering.entity.GatheringMemberStatus;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.stereotype.Repository;
@@ -123,4 +124,48 @@ List<GatheringMember> findMyGatheringsAfterCursor(
             "AND g.gatheringStatus = 'ACTIVE' " +
             "AND gm.removedAt IS NULL")
     int countMyGatherings(@Param("userId") Long userId);
+
+    /**
+     * 모임 멤버 상태별 조회 (첫 페이지)
+     */
+    @Query("SELECT gm FROM GatheringMember gm " +
+            "JOIN FETCH gm.user u " +
+            "WHERE gm.gathering.id = :gatheringId " +
+            "AND gm.memberStatus = :status " +
+            "AND gm.removedAt IS NULL " +
+            "ORDER BY gm.id DESC")
+    List<GatheringMember> findMembersByStatusFirstPage(
+            @Param("gatheringId") Long gatheringId,
+            @Param("status") GatheringMemberStatus status,
+            Pageable pageable
+    );
+
+    /**
+     * 모임 멤버 상태별 조회 (다음 페이지)
+     */
+    @Query("SELECT gm FROM GatheringMember gm " +
+            "JOIN FETCH gm.user u " +
+            "WHERE gm.gathering.id = :gatheringId " +
+            "AND gm.memberStatus = :status " +
+            "AND gm.removedAt IS NULL " +
+            "AND gm.id < :cursorId " +
+            "ORDER BY gm.id DESC")
+    List<GatheringMember> findMembersByStatusAfterCursor(
+            @Param("gatheringId") Long gatheringId,
+            @Param("status") GatheringMemberStatus status,
+            @Param("cursorId") Long cursorId,
+            Pageable pageable
+    );
+
+    /**
+     * 모임 멤버 상태별 총 개수 조회
+     */
+    @Query("SELECT count(gm) FROM GatheringMember gm " +
+            "WHERE gm.gathering.id = :gatheringId " +
+            "AND gm.memberStatus = :status " +
+            "AND gm.removedAt IS NULL")
+    int countMembersByStatus(
+            @Param("gatheringId") Long gatheringId,
+            @Param("status") GatheringMemberStatus status
+    );
 }

src/main/java/com/dokdok/gathering/service/GatheringService.java

@@ -1,6 +1,5 @@
 package com.dokdok.gathering.service;
 
-import com.dokdok.book.entity.Book;
 import com.dokdok.book.repository.BookReviewRepository;
 import com.dokdok.gathering.dto.request.GatheringCreateRequest;
 import com.dokdok.gathering.dto.request.GatheringUpdateRequest;
@@ -15,7 +14,6 @@
 import com.dokdok.global.response.PageResponse;
 import com.dokdok.global.util.SecurityUtil;
 import com.dokdok.gathering.util.InvitationCodeGenerator;
-import com.dokdok.meeting.entity.MeetingMember;
 import com.dokdok.meeting.entity.MeetingStatus;
 import com.dokdok.meeting.repository.MeetingMemberRepository;
 import com.dokdok.meeting.repository.MeetingRepository;
@@ -28,12 +26,10 @@
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
-import java.math.BigDecimal;
 import java.time.LocalDateTime;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.function.Function;
 import java.util.stream.Collectors;
 
 @Service
@@ -347,6 +343,55 @@ public void updateFavorite(Long gatheringId) {
         member.updateFavorite();
     }
 
+    /**
+     * 모임 멤버 관리 목록을 상태별로 조회합니다. (커시 기반 무한 스크롤)
+     */
+    public CursorResponse<GatheringMemberResponse, GatheringMemberCursor> getGatheringMembers(
+            Long gatheringId,
+            GatheringMemberStatus status,
+            int pageSize,
+            Long cursorId
+    ) {
+        Long userId = SecurityUtil.getCurrentUserId();
+
+        // 모임 존재 여부 및 리더 권한 검증
+        gatheringValidator.validateAndGetGathering(gatheringId);
+        gatheringValidator.validateLeader(gatheringId, userId);
+
+        Pageable pageable = PageRequest.of(0, pageSize +1);
+
+        List<GatheringMember> members;
+        Integer totalCount = null;
+
+        if (cursorId == null) {
+            // 첫 페이지
+            members = gatheringMemberRepository.findMembersByStatusFirstPage(gatheringId, status, pageable);
+            totalCount = gatheringMemberRepository.countMembersByStatus(gatheringId, status);
+        } else {
+            // 다음 페이지
+            members = gatheringMemberRepository.findMembersByStatusAfterCursor(gatheringId, status, cursorId, pageable);
+        }
+
+        boolean hasNext = members.size() > pageSize;
+        List<GatheringMember> pageMembers = hasNext ? members.subList(0, pageSize) : members;
+
+        List<GatheringMemberResponse> items = pageMembers.stream()
+                .map(member -> {
+                    String presignedUrl = storageService.getPresignedProfileImage(
+                            member.getUser().getProfileImageUrl()
+                    );
+                    return GatheringMemberResponse.from(member, presignedUrl);
+                })
+                .toList();
+
+        GatheringMember lastMember = pageMembers.isEmpty() ? null : pageMembers.get(pageMembers.size() - 1);
+        GatheringMemberCursor nextCursor = hasNext && lastMember != null
+                ? GatheringMemberCursor.from(lastMember)
+                : null;
+
+        return CursorResponse.of(items, pageSize, hasNext, nextCursor, totalCount);
+    }
+
     /**
      * 공통 메서드
      * 모임 멤버를 추가합니다.