Feat: 개인 채팅 관련 DTO 생성

Author: jueunk617

src/main/java/com/back/domain/chat/dm/dto/ConversationListResponse.java

@@ -0,0 +1,25 @@
+package com.back.domain.chat.dm.dto;
+
+import java.time.LocalDateTime;
+import java.util.List;
+
+public record ConversationListResponse(
+        List<ConversationDto> conversations
+) {
+
+    // 개별 대화 정보 DTO
+    public record ConversationDto(
+            Long userId,
+            String nickname,
+            String profileImageUrl,
+            LastMessageDto lastMessage,
+            Integer unreadCount
+    ) {}
+
+    // 마지막 메시지 정보 DTO
+    public record LastMessageDto(
+            String content,
+            LocalDateTime createdAt,
+            Boolean isRead
+    ) {}
+}

src/main/java/com/back/domain/chat/dm/dto/PrivateMessageHistoryResponse.java

@@ -0,0 +1,29 @@
+package com.back.domain.chat.dm.dto;
+
+import java.time.LocalDateTime;
+import java.util.List;
+
+public record PrivateMessageHistoryResponse(
+        List<PrivateMessageDto> content,
+        PageableDto pageable
+) {
+
+    // 개인 메시지 정보 DTO
+    public record PrivateMessageDto(
+            Long messageId,
+            Long fromUserId,
+            Long toUserId,
+            String content,
+            String messageType,
+            PrivateMessageResponse.AttachmentDto attachment,
+            LocalDateTime createdAt,
+            Boolean isRead
+    ) {}
+
+    // 페이징 정보 DTO
+    public record PageableDto(
+            Integer page,
+            Integer size,
+            Boolean hasNext
+    ) {}
+}

src/main/java/com/back/domain/chat/dm/dto/PrivateMessageRequest.java

@@ -0,0 +1,27 @@
+package com.back.domain.chat.dm.dto;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public record PrivateMessageRequest(
+        @NotNull(message = "수신자 ID는 필수입니다")
+        Long toUserId,
+
+        @NotBlank(message = "메시지 내용은 필수입니다")
+        String content,
+
+        String messageType,  // TEXT, IMAGE, FILE 등 (기본값: TEXT)
+
+        Long attachmentId    // 첨부파일 ID (선택사항)
+) {
+
+    // 기본값 처리를 위한 정적 팩토리 메서드
+    public static PrivateMessageRequest of(Long toUserId, String content) {
+        return new PrivateMessageRequest(toUserId, content, "TEXT", null);
+    }
+
+    // messageType 기본값 처리
+    public String messageType() {
+        return messageType != null ? messageType : "TEXT";
+    }
+}

src/main/java/com/back/domain/chat/dm/dto/PrivateMessageResponse.java

@@ -0,0 +1,53 @@
+package com.back.domain.chat.dm.dto;
+
+import java.time.LocalDateTime;
+
+public record PrivateMessageResponse(
+        Long messageId,
+        Long fromUserId,
+        Long toUserId,
+        String fromNickname,
+        String fromProfileImageUrl,
+        String content,
+        String messageType,
+        AttachmentDto attachment,
+        LocalDateTime createdAt
+) {
+
+    /**
+     * 첨부파일 정보 DTO
+     */
+    public record AttachmentDto(
+            Long id,
+            String originalName,
+            String url,
+            Long size,
+            String mimeType
+    ) {}
+
+    /**
+     * 텍스트 메시지 응답 생성 헬퍼 메서드
+     */
+    public static PrivateMessageResponse createTextMessage(
+            Long messageId,
+            Long fromUserId,
+            Long toUserId,
+            String fromNickname,
+            String fromProfileImageUrl,
+            String content,
+            LocalDateTime createdAt) {
+
+        return new PrivateMessageResponse(
+                messageId,
+                fromUserId,
+                toUserId,
+                fromNickname,
+                fromProfileImageUrl,
+                content,
+                "TEXT",
+                null, // attachment
+                createdAt
+        );
+    }
+}
+