[Backend] feat: SSE 알림에 presigned URL 로직 추가

backend/src/main/java/com/example/backend/dashboard/service/CaseDetectService.java

@@ -1,5 +1,8 @@
 package com.example.backend.dashboard.service;
 
+import com.amazonaws.HttpMethod;
+import com.amazonaws.services.s3.AmazonS3;
+import com.amazonaws.services.s3.model.GeneratePresignedUrlRequest;
 import com.example.backend.common.domain.CaseEntity;
 import com.example.backend.common.domain.CctvEntity;
 import com.example.backend.common.domain.OfficeEntity;
@@ -9,10 +12,13 @@
 import com.example.backend.search.repository.CctvRepository;
 import jakarta.persistence.EntityNotFoundException;
 import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import java.time.LocalDateTime;
+import java.util.Date;
+import java.util.concurrent.TimeUnit;
 
 @Service
 @Transactional
@@ -22,6 +28,10 @@ public class CaseDetectService {
     private final DashboardRepository caseRepository;
     private final CctvRepository cctvRepository; // CCTV 정보(주소) 조회용
 
+    @Value("${cloud.aws.bucket}")
+    private String bucket;
+    private final AmazonS3 s3Client;
+
     public CaseDetectResponse saveCase(CaseDetectRequest request) {
         // 1) CCTV 정보 조회 (주소 포함)
         CctvEntity cctvEntity = cctvRepository.findById(request.getCctvId())
@@ -48,7 +58,23 @@ public CaseDetectResponse saveCase(CaseDetectRequest request) {
 
         CaseEntity saved = caseRepository.save(caseEntity);
 
+        CaseDetectResponse detect_case = CaseDetectResponse.fromEntity(saved);
+
+        // Presigned URL 유효기간 설정 (30분)
+        Date expiration = new Date();
+        long expTime = expiration.getTime();
+        expTime += TimeUnit.MINUTES.toMillis(30);   // 30 minute
+        expiration.setTime(expTime);
+
+        GeneratePresignedUrlRequest presignRequest =
+                new GeneratePresignedUrlRequest(bucket, detect_case.getVideo())
+                        .withMethod(HttpMethod.GET)
+                        .withExpiration(expiration);
+
+        String url = s3Client.generatePresignedUrl(presignRequest).toString();
+        detect_case.setVideo(url);
+
         // 3) DTO 변환: 기존에 정의한 fromEntity 메서드를 사용하여 응답 객체 생성
-        return CaseDetectResponse.fromEntity(saved);
+        return detect_case;
     }
 }