refactor: 채팅 서비스 코드 중복 제거 및 단순화

src/main/java/gg/agit/konect/domain/chat/service/ChatRoomMembershipService.java

@@ -20,7 +20,6 @@
 import gg.agit.konect.domain.club.model.Club;
 import gg.agit.konect.domain.club.model.ClubMember;
 import gg.agit.konect.domain.club.repository.ClubMemberRepository;
-import gg.agit.konect.domain.user.enums.UserRole;
 import gg.agit.konect.domain.user.model.User;
 import gg.agit.konect.domain.user.repository.UserRepository;
 import gg.agit.konect.global.exception.CustomException;
@@ -33,7 +32,7 @@
 @Transactional(readOnly = true)
 public class ChatRoomMembershipService {
 
-    private static final int SYSTEM_ADMIN_ID = 1;
+    public static final int SYSTEM_ADMIN_ID = 1;
 
     private final ChatRoomRepository chatRoomRepository;
     private final ChatRoomMemberRepository chatRoomMemberRepository;
@@ -68,7 +67,7 @@ public void updateLastReadAt(Integer roomId, Integer userId, LocalDateTime readA
     @Transactional(propagation = Propagation.REQUIRES_NEW)
     public void updateDirectRoomLastReadAt(Integer roomId, User user, LocalDateTime readAt, ChatRoom room) {
         // 어드민이 SYSTEM_ADMIN 방의 메시지를 읽으면 SYSTEM_ADMIN의 lastReadAt을 업데이트
-        if (user.getRole() == UserRole.ADMIN && isSystemAdminRoom(roomId)) {
+        if (user.isAdmin() && isSystemAdminRoom(roomId)) {
             chatRoomMemberRepository.updateLastReadAtIfOlder(roomId, SYSTEM_ADMIN_ID, readAt);
             return;
         }
@@ -134,7 +133,7 @@ private void ensureDirectRoomMemberExists(ChatRoom room, User user, LocalDateTim
 
         // 어드민은 SYSTEM_ADMIN 방의 메시지를 조회할 수 있지만, 멤버로 추가되지는 않는다
         // (멤버가 추가되면 findByTwoUsers에서 해당 방을 찾지 못해 채팅방이 중복 생성됨)
-        if (user.getRole() == UserRole.ADMIN && isSystemAdminRoom(room.getId())) {
+        if (user.isAdmin() && isSystemAdminRoom(room.getId())) {
             return;
         }
 

src/main/java/gg/agit/konect/domain/chat/service/ChatService.java

@@ -1,5 +1,6 @@
 package gg.agit.konect.domain.chat.service;
 
+import static gg.agit.konect.domain.chat.service.ChatRoomMembershipService.SYSTEM_ADMIN_ID;
 import static gg.agit.konect.global.code.ApiResponseCode.*;
 
 import java.time.LocalDateTime;
@@ -69,7 +70,6 @@
 @Transactional(readOnly = true)
 public class ChatService {
 
-    private static final int SYSTEM_ADMIN_ID = 1;
     private static final String ETC_SECTION_NAME = "기타";
     private static final String DEFAULT_GROUP_ROOM_NAME = "그룹 채팅";
 
@@ -94,7 +94,7 @@ public ChatRoomResponse createOrGetChatRoom(Integer currentUserId, ChatRoomCreat
             throw CustomException.of(CANNOT_CREATE_CHAT_ROOM_WITH_SELF);
         }
 
-        if (currentUser.getRole() == UserRole.ADMIN && targetUser.getRole() != UserRole.ADMIN) {
+        if (currentUser.isAdmin() && !targetUser.isAdmin()) {
             return getOrCreateSystemAdminChatRoomForUser(targetUser, currentUser);
         }
 
@@ -396,7 +396,7 @@ public ChatMessagePageResponse getMessages(Integer userId, Integer roomId, Integ
         LocalDateTime readAt = LocalDateTime.now();
 
         if (room.isDirectRoom()) {
-            boolean isAdminViewingSystemRoom = user.getRole() == UserRole.ADMIN && isSystemAdminRoom(room);
+            boolean isAdminViewingSystemRoom = user.isAdmin() && isSystemAdminRoom(room);
             if (isAdminViewingSystemRoom) {
                 chatRoomMembershipService.updateLastReadAt(roomId, SYSTEM_ADMIN_ID, readAt);
                 recordPresenceSafely(roomId, userId);
@@ -448,7 +448,7 @@ public ChatMuteResponse toggleMute(Integer userId, Integer roomId) {
             ensureRoomMember(room, member.getUser(), member.getCreatedAt());
         } else if (room.isDirectRoom()) {
             // 어드민이 SYSTEM_ADMIN 방에 접근하는 경우는 멤버십 체크를 건너뜀
-            boolean isAdminAccessingSystemAdminRoom = user.getRole() == UserRole.ADMIN
+            boolean isAdminAccessingSystemAdminRoom = user.isAdmin()
                 && isSystemAdminRoom(room);
             if (!isAdminAccessingSystemAdminRoom) {
                 getAccessibleDirectRoomMember(room, user);
@@ -491,7 +491,7 @@ public void updateChatRoomName(Integer userId, Integer roomId, ChatRoomNameUpdat
     private List<ChatRoomSummaryResponse> getDirectChatRooms(Integer userId) {
         User user = userRepository.getById(userId);
 
-        if (user.getRole() == UserRole.ADMIN) {
+        if (user.isAdmin()) {
             return getAdminDirectChatRooms(userId);
         }
 
@@ -620,37 +620,38 @@ private List<ChatRoomSummaryResponse> getGroupChatRooms(Integer userId) {
             .toList();
     }
 
-    private ChatMessagePageResponse getDirectChatRoomMessages(
-        Integer userId,
+    private ChatMessagePageResponse buildDirectChatRoomMessages(
+        User user,
         Integer roomId,
         Integer page,
         Integer limit,
-        LocalDateTime readAt
+        LocalDateTime readAt,
+        LocalDateTime visibleMessageFrom,
+        List<LocalDateTime> sortedReadBaselines,
+        Integer maskedAdminId
     ) {
-        ChatRoom chatRoom = getDirectRoom(roomId);
-        User user = userRepository.getById(userId);
-        List<ChatRoomMember> members = chatRoomMemberRepository.findByChatRoomId(roomId);
-        LocalDateTime visibleMessageFrom = prepareDirectRoomAccess(getOrCreateDirectRoomMember(chatRoom, user),
-            chatRoom);
-
         PageRequest pageable = PageRequest.of(page - 1, limit);
         Page<ChatMessage> messages = chatMessageRepository.findByChatRoomId(roomId, visibleMessageFrom, pageable);
 
-        List<LocalDateTime> sortedReadBaselines = toSortedReadBaselines(members);
-
         List<ChatMessageDetailResponse> responseMessages = messages.getContent().stream()
             .map(message -> {
-                boolean isRead = message.isSentBy(userId) || !message.getCreatedAt().isAfter(readAt);
+                Integer senderId = maskedAdminId != null
+                    ? resolveDirectSenderId(message, maskedAdminId)
+                    : message.getSender().getId();
+                boolean isMine = maskedAdminId != null
+                    ? shouldDisplayAsOwnMessage(user, message, true)
+                    : message.isSentBy(user.getId());
+                boolean isRead = isMine || !message.getCreatedAt().isAfter(readAt);
                 int unreadCount = countUnreadSince(message.getCreatedAt(), sortedReadBaselines);
                 return new ChatMessageDetailResponse(
                     message.getId(),
-                    message.getSender().getId(),
+                    senderId,
                     null,
                     message.getContent(),
                     message.getCreatedAt(),
                     isRead,
                     unreadCount,
-                    message.isSentBy(userId)
+                    isMine
                 );
             })
             .toList();
@@ -665,6 +666,25 @@ private ChatMessagePageResponse getDirectChatRoomMessages(
         );
     }
 
+    private ChatMessagePageResponse getDirectChatRoomMessages(
+        Integer userId,
+        Integer roomId,
+        Integer page,
+        Integer limit,
+        LocalDateTime readAt
+    ) {
+        ChatRoom chatRoom = getDirectRoom(roomId);
+        User user = userRepository.getById(userId);
+        List<ChatRoomMember> members = chatRoomMemberRepository.findByChatRoomId(roomId);
+        LocalDateTime visibleMessageFrom = prepareDirectRoomAccess(getOrCreateDirectRoomMember(chatRoom, user),
+            chatRoom);
+
+        List<LocalDateTime> sortedReadBaselines = toSortedReadBaselines(members);
+
+        return buildDirectChatRoomMessages(user, roomId, page, limit, readAt,
+            visibleMessageFrom, sortedReadBaselines, null);
+    }
+
     private ChatMessagePageResponse getAdminSystemDirectChatRoomMessages(
         User user,
         ChatRoom chatRoom,
@@ -676,39 +696,11 @@ private ChatMessagePageResponse getAdminSystemDirectChatRoomMessages(
         List<ChatRoomMember> members = chatRoomMemberRepository.findByChatRoomId(roomId);
         LocalDateTime visibleMessageFrom = resolveAdminSystemRoomVisibleMessageFrom(members);
 
-        PageRequest pageable = PageRequest.of(page - 1, limit);
-        Page<ChatMessage> messages = chatMessageRepository.findByChatRoomId(roomId, visibleMessageFrom, pageable);
-
         List<LocalDateTime> sortedReadBaselines = toAdminChatReadBaselines(members);
-
         Integer maskedAdminId = getMaskedAdminId(user, chatRoom);
-        List<ChatMessageDetailResponse> responseMessages = messages.getContent().stream()
-            .map(message -> {
-                Integer senderId = resolveDirectSenderId(message, maskedAdminId);
-                boolean isMine = shouldDisplayAsOwnMessage(user, message, true);
-                boolean isRead = isMine || !message.getCreatedAt().isAfter(readAt);
-                int unreadCount = countUnreadSince(message.getCreatedAt(), sortedReadBaselines);
-                return new ChatMessageDetailResponse(
-                    message.getId(),
-                    senderId,
-                    null,
-                    message.getContent(),
-                    message.getCreatedAt(),
-                    isRead,
-                    unreadCount,
-                    isMine
-                );
-            })
-            .toList();
 
-        return new ChatMessagePageResponse(
-            messages.getTotalElements(),
-            messages.getNumberOfElements(),
-            messages.getTotalPages(),
-            messages.getNumber() + 1,
-            null,
-            responseMessages
-        );
+        return buildDirectChatRoomMessages(user, roomId, page, limit, readAt,
+            visibleMessageFrom, sortedReadBaselines, maskedAdminId);
     }
 
     private ChatMessageDetailResponse sendDirectMessage(
@@ -720,7 +712,7 @@ private ChatMessageDetailResponse sendDirectMessage(
         User sender = userRepository.getById(userId);
 
         // 어드민이 SYSTEM_ADMIN 방에 메시지를 보내는 경우
-        boolean isAdminSendingToSystemAdminRoom = sender.getRole() == UserRole.ADMIN
+        boolean isAdminSendingToSystemAdminRoom = sender.isAdmin()
             && isSystemAdminRoom(chatRoom);
 
         ChatRoomMember senderMember = null;
@@ -1175,7 +1167,7 @@ private Map<Integer, Integer> getUnreadCountMap(List<Integer> chatRoomIds, Integ
     }
 
     private Integer getMaskedAdminId(User user, ChatRoom chatRoom) {
-        if (user.getRole() == UserRole.ADMIN) {
+        if (user.isAdmin()) {
             return null;
         }
 
@@ -1197,7 +1189,7 @@ private Integer getMaskedAdminId(User user, ChatRoom chatRoom) {
     }
 
     private void publishAdminChatEventIfNeeded(boolean isSystemAdminRoom, User sender, String content) {
-        if (isSystemAdminRoom && sender.getRole() != UserRole.ADMIN) {
+        if (isSystemAdminRoom && !sender.isAdmin()) {
             eventPublisher.publishEvent(AdminChatReceivedEvent.of(sender.getId(), sender.getName(), content));
         }
     }
@@ -1260,7 +1252,7 @@ private void ensureDirectRoomRequester(ChatRoom room, User user, LocalDateTime j
     private boolean shouldSkipSystemAdminMembership(ChatRoom room, User user) {
         // 문의방은 SYSTEM_ADMIN + 일반 사용자 2인 구조를 전제로 재사용(findByTwoUsers)되므로,
         // 생성/재오픈 경로에서도 일반 ADMIN을 멤버로 추가하면 안 된다.
-        return user.getRole() == UserRole.ADMIN && isSystemAdminRoom(room);
+        return user.isAdmin() && isSystemAdminRoom(room);
     }
 
     private String normalizeCustomRoomName(String roomName) {
@@ -1296,19 +1288,18 @@ private void updateClubMessageLastReadAt(Integer roomId, Integer userId, LocalDa
     }
 
     private List<LocalDateTime> toSortedReadBaselines(List<ChatRoomMember> members) {
-        List<LocalDateTime> baselines = members.stream()
+        return members.stream()
             .map(ChatRoomMember::getLastReadAt)
             .sorted()
             .toList();
-        return baselines;
     }
 
     private List<LocalDateTime> toAdminChatReadBaselines(List<ChatRoomMember> members) {
         LocalDateTime adminLastReadAt = null;
         LocalDateTime userLastReadAt = null;
 
         for (ChatRoomMember member : members) {
-            if (member.getUser().getRole() == UserRole.ADMIN) {
+            if (member.getUser().isAdmin()) {
                 if (adminLastReadAt == null || member.getLastReadAt().isAfter(adminLastReadAt)) {
                     adminLastReadAt = member.getLastReadAt();
                 }
@@ -1383,7 +1374,7 @@ private ChatRoomMember getOrCreateDirectRoomMember(ChatRoom chatRoom, User user)
         return chatRoomMemberRepository.findByChatRoomIdAndUserId(chatRoom.getId(), user.getId())
             .orElseGet(() -> {
                 // 어드민은 SYSTEM_ADMIN 방에 멤버로 추가되지 않음
-                if (user.getRole() == UserRole.ADMIN && isSystemAdminRoom(chatRoom)) {
+                if (user.isAdmin() && isSystemAdminRoom(chatRoom)) {
                     throw CustomException.of(FORBIDDEN_CHAT_ROOM_ACCESS);
                 }
                 throw CustomException.of(FORBIDDEN_CHAT_ROOM_ACCESS);
@@ -1440,13 +1431,13 @@ private boolean shouldDisplayAsOwnMessage(
         boolean isAdminViewingSystemRoom
     ) {
         if (isAdminViewingSystemRoom) {
-            return message.getSender().getRole() == UserRole.ADMIN;
+            return message.getSender().isAdmin();
         }
         return message.isSentBy(currentUser.getId());
     }
 
     private Integer resolveDirectSenderId(ChatMessage message, Integer maskedAdminId) {
-        if (maskedAdminId != null && message.getSender().getRole() == UserRole.ADMIN) {
+        if (maskedAdminId != null && message.getSender().isAdmin()) {
             return maskedAdminId;
         }
         return message.getSender().getId();
@@ -1531,26 +1522,29 @@ private User resolveDirectChatPartner(List<ChatRoomMember> members, Integer user
     }
 
     private User findNonAdminUser(List<ChatRoomMember> members) {
-        return members.stream()
-            .map(ChatRoomMember::getUser)
-            .filter(memberUser -> memberUser.getRole() != UserRole.ADMIN)
-            .findFirst()
-            .orElse(null);
+        Map<Integer, User> userMap = members.stream()
+            .collect(Collectors.toMap(
+                ChatRoomMember::getUserId,
+                ChatRoomMember::getUser,
+                (existing, replacement) -> existing
+            ));
+        List<MemberInfo> memberInfos = members.stream()
+            .map(m -> new MemberInfo(m.getUserId(), m.getCreatedAt()))
+            .toList();
+        return findNonAdminUserFromMemberInfo(memberInfos, userMap);
     }
 
     private User resolveDirectMessageReceiver(List<ChatRoomMember> members, User sender) {
-        if (sender.getRole() == UserRole.ADMIN) {
-            User nonAdminUser = findNonAdminUser(members);
-            if (nonAdminUser != null) {
-                return nonAdminUser;
-            }
-        }
-
-        User partner = resolveDirectChatPartner(members, sender.getId());
-        if (partner == null) {
-            throw CustomException.of(FORBIDDEN_CHAT_ROOM_ACCESS);
-        }
-        return partner;
+        Map<Integer, User> userMap = members.stream()
+            .collect(Collectors.toMap(
+                ChatRoomMember::getUserId,
+                ChatRoomMember::getUser,
+                (existing, replacement) -> existing
+            ));
+        List<MemberInfo> memberInfos = members.stream()
+            .map(m -> new MemberInfo(m.getUserId(), m.getCreatedAt()))
+            .toList();
+        return resolveMessageReceiverFromMemberInfo(sender, memberInfos, userMap);
     }
 
     private User findDirectPartnerFromMemberInfo(
@@ -1585,7 +1579,7 @@ private User findNonAdminUserFromMemberInfo(List<MemberInfo> memberInfos, Map<In
             .sorted(Comparator.comparing(MemberInfo::createdAt))
             .map(info -> userMap.get(info.userId()))
             .filter(Objects::nonNull)
-            .filter(user -> user.getRole() != UserRole.ADMIN)
+            .filter(user -> !user.isAdmin())
             .findFirst()
             .orElse(null);
     }
@@ -1595,7 +1589,7 @@ private User resolveMessageReceiverFromMemberInfo(
         List<MemberInfo> memberInfos,
         Map<Integer, User> userMap
     ) {
-        if (sender.getRole() == UserRole.ADMIN) {
+        if (sender.isAdmin()) {
             User nonAdminUser = findNonAdminUserFromMemberInfo(memberInfos, userMap);
             if (nonAdminUser != null) {
                 return nonAdminUser;