Feat: FCM Config 설정 추가

backend/src/main/java/com/worlabel/global/config/FCMConfig.java

@@ -1,9 +1,20 @@
 package com.worlabel.global.config;
 
+import com.google.auth.oauth2.GoogleCredentials;
+import com.google.firebase.FirebaseApp;
+import com.google.firebase.FirebaseOptions;
+import com.google.firebase.messaging.FirebaseMessaging;
+import com.worlabel.global.exception.CustomException;
+import com.worlabel.global.exception.ErrorCode;
 import lombok.RequiredArgsConstructor;
-import lombok.Value;
 import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.io.ClassPathResource;
+
+import java.io.IOException;
+import java.io.InputStream;
 
 @Slf4j
 @Configuration
@@ -11,4 +22,30 @@ import org.springframework.context.annotation.Configuration;
 public class FCMConfig {
 
     // Firebase 설정 Json 파일의 경로
+    @Value("${fcm.config.path}")
+    private String FIREBASE_CONFIG_PATH;
+
+    @Bean
+    FirebaseMessaging firebaseMessaging() {
+        // 클래스패스에서 Firebase 설정 파일을 리소스로 불러옴
+        ClassPathResource resource = new ClassPathResource(FIREBASE_CONFIG_PATH);
+
+        // JSON 파일에서 자격 증명을 불러와 Firebase 옵션을 설정
+        try (InputStream serviceAccount = resource.getInputStream()) {
+            FirebaseOptions options = FirebaseOptions.builder()
+                    .setCredentials(GoogleCredentials.fromStream(serviceAccount))
+                    .build();
+
+            // FirebaseApp 인스턴스가 초기화되지 않은 경우 초기화, 이미 존재하는 경우 해당 인스턴스를 가져옴
+            FirebaseApp firebaseApp = FirebaseApp.getApps().isEmpty() ?
+                    FirebaseApp.initializeApp(options) :
+                    FirebaseApp.getInstance();
+            log.debug("firebase 불러오기 성공");
+            // 설정된 FirebaseApp 연결된 FirebaseMessaging 인스턴스를 반환
+            return FirebaseMessaging.getInstance(firebaseApp);
+        } catch (IOException e) {
+            throw new CustomException(ErrorCode.SERVER_ERROR, "Firebase Key 불러오기 실패 ");
+        }
+    }
+
 }