MATE-109 : [FEAT] 메이트 채팅방 멤버 조회 기능 (#101)

* MATE-109 : [FEAT] 채팅방 멤버 조회 컨트롤러 구현

* MATE-109 : [FEAT] 채팅방 멤버 조회 서비스 구현

src/main/java/com/example/mate/domain/mateChat/controller/MateChatRoomController.java

@@ -1,14 +1,13 @@
 package com.example.mate.domain.mateChat.controller;
 
-import com.example.mate.common.error.CustomException;
-import com.example.mate.common.error.ErrorCode;
 import com.example.mate.common.response.ApiResponse;
 import com.example.mate.common.response.PageResponse;
 import com.example.mate.common.security.auth.AuthMember;
 import com.example.mate.domain.mateChat.dto.response.MateChatMessageResponse;
 import com.example.mate.domain.mateChat.dto.response.MateChatRoomListResponse;
 import com.example.mate.domain.mateChat.dto.response.MateChatRoomResponse;
 import com.example.mate.domain.mateChat.service.MateChatRoomService;
+import com.example.mate.domain.member.dto.response.MemberSummaryResponse;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.Parameter;
 import io.swagger.v3.oas.annotations.tags.Tag;
@@ -19,6 +18,8 @@
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
 import org.springframework.web.bind.annotation.*;
 
+import java.util.List;
+
 @RestController
 @RequiredArgsConstructor
 @RequestMapping("/api/mates/chat")
@@ -43,10 +44,6 @@ public ResponseEntity<ApiResponse<PageResponse<MateChatRoomListResponse>>> getMy
                                                     @AuthenticationPrincipal AuthMember member
 
             ) {
-
-        if (member == null) {
-            throw new CustomException(ErrorCode.UNAUTHORIZED_USER);
-        }
         PageResponse<MateChatRoomListResponse> response = chatRoomService.getMyChatRooms(member.getMemberId(), pageable);
         return ResponseEntity.ok(ApiResponse.success(response));
     }
@@ -81,4 +78,12 @@ public ResponseEntity<Void> leaveChatRoom(
         chatRoomService.leaveChatRoom(chatroomId, member.getMemberId());
         return ResponseEntity.noContent().build();
     }
+
+    @GetMapping("/{chatRoomId}/members")
+    @Operation(summary = "채팅방 멤버 조회", description = "채팅방에 현재 참여 중인 멤버 목록을 조회합니다.")
+    public ResponseEntity<ApiResponse<List<MemberSummaryResponse>>> getMateChatRoomMembers(@Parameter(description = "채팅방 ID") @PathVariable Long chatRoomId,
+                                                                                             @AuthenticationPrincipal AuthMember member) {
+        List<MemberSummaryResponse> responses = chatRoomService.getChatRoomMembers(chatRoomId, member.getMemberId());
+        return ResponseEntity.ok(ApiResponse.success(responses));
+    }
 }

src/main/java/com/example/mate/domain/mateChat/service/MateChatRoomService.java

@@ -19,6 +19,7 @@
 import com.example.mate.domain.mateChat.repository.MateChatMessageRepository;
 import com.example.mate.domain.mateChat.repository.MateChatRoomMemberRepository;
 import com.example.mate.domain.mateChat.repository.MateChatRoomRepository;
+import com.example.mate.domain.member.dto.response.MemberSummaryResponse;
 import com.example.mate.domain.member.entity.Member;
 import com.example.mate.domain.member.repository.MemberRepository;
 import lombok.RequiredArgsConstructor;
@@ -31,6 +32,7 @@
 import java.time.LocalDateTime;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 @Service
 @Transactional
@@ -43,6 +45,7 @@ public class MateChatRoomService {
     private final MemberRepository memberRepository;
     private final MateChatMessageService mateChatMessageService;
     private final VisitPartRepository visitPartRepository;
+    private final MateChatRoomMemberRepository mateChatRoomMemberRepository;
 
     // 메이트 게시글에서 채팅방 생성/입장
     public MateChatRoomResponse createOrJoinChatRoomFromPost(Long postId, Long memberId) {
@@ -185,6 +188,23 @@ private MateChatRoomMember joinAsMember(MateChatRoom chatRoom, Member member) {
         return chatRoomMemberRepository.save(chatRoomMember);
     }
 
+    // 채팅방 현재 명단 조회
+    @Transactional(readOnly = true)
+    public List<MemberSummaryResponse> getChatRoomMembers(Long roomId, Long memberId) {
+
+        // 1. 채팅방 접근 권한 검증
+        validateChatRoomAccess(roomId, memberId);
+
+        // 2. 활성화된 채팅방 멤버 조회
+        List<MateChatRoomMember> activeMembers = mateChatRoomMemberRepository.findActiveMembers(roomId);
+
+
+        // 3. MemberSummaryResponse로 변환하여 반환
+        return activeMembers.stream()
+                .map(member -> MemberSummaryResponse.from(member.getMember()))
+                .collect(Collectors.toList());
+    }
+
     // 채팅방 퇴장
     public void leaveChatRoom(Long roomId, Long memberId) {
         MateChatRoom chatRoom = chatRoomRepository.findById(roomId)