Feat: CHAT-223-채팅-조회-API (#28)

* Feat: 채팅 조회 기능 구현

* Refactor: 채팅 10개 반환

src/main/java/com/kuit/chatdiary/controller/ChatController.java

@@ -0,0 +1,30 @@
+package com.kuit.chatdiary.controller;
+
+import com.kuit.chatdiary.dto.chat.ChatGetResponseDTO;
+import com.kuit.chatdiary.service.ChatService;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.Collections;
+import java.util.List;
+
+@Slf4j
+@RestController
+@RequestMapping("/chat")
+public class ChatController {
+
+    @Autowired
+    private ChatService chatService;
+
+    @GetMapping("/get")
+    public ResponseEntity<List<ChatGetResponseDTO>> getChats(@RequestParam Long chatId) {
+        List<ChatGetResponseDTO> chats = chatService.getChats(chatId);
+        if (chats == null) {
+            return ResponseEntity.status(HttpStatus.NOT_FOUND).body(Collections.emptyList());
+        }
+        return ResponseEntity.ok(chatService.getChats(chatId));
+    }
+}

src/main/java/com/kuit/chatdiary/dto/chat/ChatGetResponseDTO.java

@@ -0,0 +1,26 @@
+package com.kuit.chatdiary.dto.chat;
+
+import com.kuit.chatdiary.domain.Chat;
+import com.kuit.chatdiary.domain.ChatType;
+import com.kuit.chatdiary.domain.Sender;
+import lombok.Getter;
+
+import java.time.LocalDateTime;
+
+@Getter
+public class ChatGetResponseDTO {
+
+    private Long chatId;
+    private LocalDateTime createAt;
+    private String content;
+    private ChatType chatType;
+    private Sender sender;
+
+    public ChatGetResponseDTO(Chat chat) {
+        this.chatId = chat.getChatId();
+        this.createAt = chat.getCreateAt();
+        this.content = chat.getContent();
+        this.chatType = chat.getChatType();
+        this.sender = chat.getSender();
+    }
+}

src/main/java/com/kuit/chatdiary/repository/ChatRepository.java

@@ -8,4 +8,5 @@
 public interface ChatRepository extends JpaRepository<Chat, Long> {
 
     List<Chat> findTop10ByMember_UserIdOrderByChatIdDesc(Long userId);
+    List<Chat> findTop10ByChatIdGreaterThan(Long lastChatId);
 }

src/main/java/com/kuit/chatdiary/service/ChatService.java

@@ -3,12 +3,16 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.*;
 import com.kuit.chatdiary.domain.*;
+import com.kuit.chatdiary.dto.chat.ChatGetResponseDTO;
 import com.kuit.chatdiary.repository.*;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Service;
 
+import java.util.List;
+import java.util.stream.Collectors;
+
 @Slf4j
 @Service
 public class ChatService {
@@ -66,4 +70,14 @@ public String extractGptResponse(String jsonResponse) throws JsonProcessingExcep
         return "";
     }
 
+    public List<ChatGetResponseDTO> getChats(Long chatId) {
+        List<Chat> chats = chatRepository.findTop10ByChatIdGreaterThan(chatId);
+        if (chats.isEmpty()) {
+            return null;
+        }
+        return chats.stream()
+                .map(ChatGetResponseDTO::new)
+                .collect(Collectors.toList());
+    }
+
 }