[#8] Friend 컨트롤러, 라우터 로직 개발

1. API endpoint를 정의하는 Friend 라우터
2. 컨트롤러
   1. 친구 요청 보내기
   2. 받은 친구 요청 목록 조회
   3. 보낸 친구 요청 목록 조회
   4. 친구 요청 수락/거절
   5. 친구 목록 조회

controllers/friendController.js

+const FriendService = require('../services/friendService');
+
+class friendController {
+    /**
+     * 친구 요청 보내기
+     * POST /api/friend/request/:friendId
+     */
+    async sendRequest(req, res) {
+        try {
+            const userId = req.user.id;
+            const { friendId } = req.params;
+
+            const request = await FriendService.sendFriendRequest(userId, friendId);
+            return res.status(201).json({
+                success: true,
+                data: request
+            });
+        } catch (error) {
+            return res.status(400).json({
+                success: false,
+                error: {
+                    message: error.message,
+                    code: 'FRIEND_REQUEST_ERROR'
+                }
+            });
+        }
+    }
+
+    /**
+     * 받은 친구 요청 목록 조회
+     * GET /api/friend/requests/received
+     */
+    async getReceivedRequests(req, res) {
+        try {
+            const userId = req.user.id;
+            const requests = await FriendService.getReceivedRequests(userId);
+
+            return res.status(200).json({
+                success: true,
+                data: requests
+            });
+        } catch (error) {
+            return res.status(500).json({
+                success: false,
+                error: {
+                    message: error.message,
+                    code: 'FETCH_ERROR'
+                }
+            });
+        }
+    }
+
+    /**
+     * 보낸 친구 요청 목록 조회
+     * GET /api/friend/requests/sent
+     */
+    async getSentRequests(req, res) {
+        try {
+            const userId = req.user.id;
+            const requests = await FriendService.getSentRequests(userId);
+
+            return res.status(200).json({
+                success: true,
+                data: requests
+            });
+        } catch (error) {
+            return res.status(500).json({
+                success: false,
+                error: {
+                    message: error.message,
+                    code: 'FETCH_ERROR'
+                }
+            });
+        }
+    }
+    
+    /**
+     * 친구 요청 수락
+     * POST /api/friend/request/:friendId/accept
+     */
+    async acceptRequest(req, res) {
+        try {
+            const userId = req.user.id;
+            const { friendId } = req.params;
+
+            const result = await FriendService.acceptFriendRequest(userId, friendId);
+
+            return res.status(200).json({
+                success: true,
+                data: result
+            });
+        } catch (error) {
+            return res.status(400).json({
+                success: false,
+                error: {
+                    message: error.message,
+                    code: 'REQUEST_ACCEPT_ERROR'
+                }
+            });
+        }
+    }
+
+    /**
+     * 친구 요청 거절
+     * POST /api/friend/request/:friendId/reject
+     */
+    async rejectRequest(req, res) {
+        try {
+            const userId = req.user.id;
+            const { friendId } = req.params;
+
+            const result = await FriendService.rejectFriendRequest(userId, friendId);
+
+            return res.status(200).json({
+                success: true,
+                data: result
+            });
+        } catch (error) {
+            return res.status(400).json({
+                success: false,
+                error: {
+                    message: error.message,
+                    code: 'REQUEST_REJECT_ERROR'
+                }
+            });
+        }
+    }
+
+    /**
+     * 친구 목록 조회
+     * GET /api/friend/all
+     */
+    async getFriendList(req, res) {
+        try {
+            const userId = req.user.id;
+            const friends = await FriendService.getFriendList(userId);
+
+            return res.status(200).json({
+                success: true,
+                data: friends
+            });
+        } catch (error) {
+            return res.status(500).json({
+                success: false,
+                error: {
+                    message: error.message,
+                    code: 'FETCH_ERROR'
+                }
+            });
+        }
+    }
+
+    /**
+     * 친구 삭제
+     * DELETE /api/friend/:friendId
+     */
+    async deleteFriend(req, res) {
+        try {
+            const userId = req.user.id;
+            const { friendId } = req.params;
+
+            const result = await FriendService.deleteFriend(userId, friendId);
+
+            return res.status(200).json({
+                success: true,
+                data: {
+                    message: 'Friend deleted successfully',
+                    result: result
+                }
+            });
+        } catch (error) {
+            return res.status(400).json({
+                success: false,
+                error: {
+                    message: error.message,
+                    code: 'FRIEND_DELETE_ERROR'
+                }
+            });
+        }
+    }
+
+}
+
+module.exports = new friendController();
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