feat: fallback 메서드 정의

Author: Kimjipang

apps/commerce-api/src/main/java/com/loopers/application/payment/PaymentFacade.java

@@ -3,6 +3,7 @@
 import com.loopers.infrastructure.payment.client.PgClient;
 import com.loopers.interfaces.api.ApiResponse;
 import com.loopers.interfaces.api.payment.PaymentV1Dto;
+import io.github.resilience4j.circuitbreaker.annotation.CircuitBreaker;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Component;
 
@@ -11,11 +12,20 @@
 public class PaymentFacade {
     private final PgClient pgClient;
 
-    public PaymentV1Dto.TransactionResponse pay(String userId, PaymentV1Dto.PaymentRequest request) {
+    @CircuitBreaker(name = "pgCircuit", fallbackMethod = "fallback")
+    public PaymentV1Dto.TransactionResponse requestPayment(String userId, PaymentV1Dto.PaymentRequest request) {
         ApiResponse<PaymentV1Dto.TransactionResponse> result = pgClient.requestPayment(userId, request);
 
         PaymentV1Dto.TransactionResponse response = result.data();
 
         return response;
     }
+
+    public PaymentV1Dto.TransactionResponse fallback(String userId, PaymentV1Dto.PaymentRequest request, Throwable throwable) {
+        return new PaymentV1Dto.TransactionResponse(
+                null,
+                PaymentV1Dto.TransactionStatusResponse.FAILED,
+                "현재 결제 서비스가 불안정합니다. 잠시 후 다시 시도해주세요."
+        );
+    }
 }