[Setting] Firebase 설정 (#25)

* feat: add submodules

* setting(build.gradle.kts): Firebase 의존성 추가

* feat(FirebaseConfig): FirebaseConfig 설정 완료

* refactor(gitmodules): 서브모듈 path 상대경로로 수정

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "src/main/resources/config"]
+	path = src/main/resources/config
+	url = https://github.com/gdsc-konkuk/Plantory-Server-Config.git

build.gradle.kts

@@ -57,6 +57,9 @@ dependencies {
     implementation("com.querydsl:querydsl-jpa:5.0.0")
     kapt("com.querydsl:querydsl-apt:5.0.0:jpa")
     kapt("org.springframework.boot:spring-boot-configuration-processor")
+
+    // firebase
+    implementation("com.google.firebase:firebase-admin:9.2.0")
 }
 
 tasks.withType<KotlinCompile> {

src/main/kotlin/gdsc/plantory/common/config/FirebaseConfig.kt

@@ -0,0 +1,52 @@
+package gdsc.plantory.common.config
+
+import com.google.auth.oauth2.GoogleCredentials
+import com.google.firebase.FirebaseApp
+import com.google.firebase.FirebaseOptions
+import com.google.firebase.messaging.FirebaseMessaging
+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.util.Optional
+
+@Configuration
+class FirebaseConfig(
+    @Value("\${fcm.key.path}")
+    private val fcmPrivateKeyPath: String
+) {
+
+    @Bean
+    fun firebaseMessaging(): FirebaseMessaging {
+        val defaultFirebaseApp = defaultFirebaseApp()
+
+        if (defaultFirebaseApp.isPresent) {
+            return FirebaseMessaging.getInstance(defaultFirebaseApp.get())
+        }
+
+        return FirebaseMessaging.getInstance(FirebaseApp.initializeApp(createFirebaseOption()))
+    }
+
+    private fun defaultFirebaseApp(): Optional<FirebaseApp> {
+        val firebaseAppList = FirebaseApp.getApps()
+
+        if (firebaseAppList == null || firebaseAppList.isEmpty()) {
+            return Optional.empty()
+        }
+
+        return firebaseAppList.stream()
+            .filter { firebaseApp: FirebaseApp -> firebaseApp.name == FirebaseApp.DEFAULT_APP_NAME }
+            .findAny()
+    }
+
+    private fun createFirebaseOption(): FirebaseOptions {
+        return FirebaseOptions.builder()
+            .setCredentials(createGoogleCredentials())
+            .build()
+    }
+
+    private fun createGoogleCredentials(): GoogleCredentials {
+        return GoogleCredentials
+            .fromStream(ClassPathResource(fcmPrivateKeyPath).inputStream)
+    }
+}

src/main/resources/application.yml

@@ -20,3 +20,7 @@ local:
 companionPlant:
   image:
     directory: photos/companionPlant
+
+fcm:
+  key:
+    path: src/main/resources/config/google-services.json