[FEAT] 카카오페이 연동 구현(#46)

build.gradle

@@ -27,6 +27,7 @@ dependencies {
     implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
     implementation 'org.springframework.boot:spring-boot-starter-security'
     implementation 'org.springframework.boot:spring-boot-starter-web'
+    implementation 'org.springframework.boot:spring-boot-starter-webflux'
     implementation 'org.springframework.boot:spring-boot-starter-validation' // 에러 핸들러 만들 때 씀
 
     testImplementation 'org.springframework.boot:spring-boot-starter-test'

src/main/java/com/sumte/payment/controller/PaymentController.java

@@ -1,6 +1,7 @@
 package com.sumte.payment.controller;
 
 import com.sumte.apiPayload.ApiResponse;
+import com.sumte.payment.dto.KakaoPayApproveResponseDTO;
 import com.sumte.payment.dto.PaymentRequestDTO;
 import com.sumte.payment.dto.PaymentResponseDTO;
 import com.sumte.payment.service.PaymentService;
@@ -33,11 +34,11 @@ public ResponseEntity<ApiResponse<PaymentResponseDTO.CreatePaymentDTO>> requestP
             summary = "결제 승인 처리 API",
             description = "PG사(예: 카카오페이) 결제 완료 후, 해당 결제 ID의 상태를 PAID로 변경합니다."
     )
-    public ResponseEntity<ApiResponse<Void>> approvePayment(
+    public ResponseEntity<ApiResponse<KakaoPayApproveResponseDTO>> approvePayment(
             @PathVariable("id") Long id,
             @RequestParam("pg_token") String pgToken) {
 
-        paymentService.approvePayment(id, pgToken);
-        return ResponseEntity.ok(ApiResponse.success(null));
+        KakaoPayApproveResponseDTO response = paymentService.approvePayment(id, pgToken);
+        return ResponseEntity.ok(ApiResponse.success(response));
     }
 }

src/main/java/com/sumte/payment/converter/PaymentConverter.java

@@ -10,10 +10,14 @@
 public class PaymentConverter {
 
     public static Payment toEntity(PaymentRequestDTO.CreatePaymentDTO dto, Reservation reservation) {
+        PaymentMethod method = dto.getPaymentMethod() != null
+                ? dto.getPaymentMethod()
+                : PaymentMethod.KAKAOPAY;
+
         return Payment.builder()
                 .reservation(reservation)
                 .paidPrice(dto.getAmount())
-                .paymentMethod(PaymentMethod.valueOf(dto.getPaymentMethod()))
+                .paymentMethod(method)
                 .paymentStatus(PaymentStatus.PENDING)
                 .build();
     }

src/main/java/com/sumte/payment/dto/KakaoPayApproveRequestDTO.java

@@ -0,0 +1,14 @@
+package com.sumte.payment.dto;
+
+import lombok.Builder;
+import lombok.Getter;
+
+@Getter
+@Builder
+public class KakaoPayApproveRequestDTO {
+    private String cid;
+    private String tid;
+    private String partner_order_id;
+    private String partner_user_id;
+    private String pg_token;
+}

src/main/java/com/sumte/payment/dto/KakaoPayApproveResponseDTO.java

@@ -0,0 +1,23 @@
+package com.sumte.payment.dto;
+
+import lombok.Builder;
+import lombok.Getter;
+
+@Getter
+@Builder
+public class KakaoPayApproveResponseDTO {
+    private String aid;
+    private String tid;
+    private String cid;
+    private String partner_order_id;
+    private String partner_user_id;
+    private String payment_method_type;
+    private Amount amount;
+
+    @Getter
+    public static class Amount {
+        private int total;
+        private int tax_free;
+        private int vat;
+    }
+}

src/main/java/com/sumte/payment/dto/KakaoPayReadyRequestDTO.java

@@ -0,0 +1,21 @@
+package com.sumte.payment.dto;
+
+import lombok.Builder;
+import lombok.Getter;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+
+@Getter
+@Builder
+public class KakaoPayReadyRequestDTO {
+    private String cid;
+    private String partner_order_id;
+    private String partner_user_id;
+    private String item_name;
+    private String quantity;
+    private String total_amount;
+    private String tax_free_amount;
+    private String approval_url;
+    private String cancel_url;
+    private String fail_url;
+}

src/main/java/com/sumte/payment/dto/KakaoPayReadyResponseDTO.java

@@ -0,0 +1,13 @@
+package com.sumte.payment.dto;
+
+import lombok.Builder;
+import lombok.Getter;
+
+@Getter
+@Builder
+public class KakaoPayReadyResponseDTO {
+    private String tid;
+    private String next_redirect_app_url;
+    private String next_redirect_pc_url;
+    private String created_at;
+}

src/main/java/com/sumte/payment/dto/PaymentRequestDTO.java

@@ -1,5 +1,6 @@
 package com.sumte.payment.dto;
 
+import com.sumte.payment.entity.PaymentMethod;
 import lombok.AllArgsConstructor;
 import lombok.Builder;
 import lombok.Getter;
@@ -14,6 +15,6 @@ public class PaymentRequestDTO {
     public static class CreatePaymentDTO {
         private Long reservationId;
         private Long amount;
-        private String paymentMethod;
+        private PaymentMethod paymentMethod;
     }
 }

src/main/java/com/sumte/payment/entity/Payment.java

@@ -52,4 +52,8 @@ public void markAsFailed() {
 		public void markAsRefunded() {
 			this.paymentStatus = PaymentStatus.REFUNDED;
 		}
+
+		public void setTid(String tid) {
+			this.tid = tid;
+		}
 	}

src/main/java/com/sumte/payment/kakaopay/KakaoPayClient.java

@@ -0,0 +1,44 @@
+package com.sumte.payment.kakaopay;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.sumte.payment.dto.KakaoPayApproveRequestDTO;
+import com.sumte.payment.dto.KakaoPayApproveResponseDTO;
+import com.sumte.payment.dto.KakaoPayReadyRequestDTO;
+import com.sumte.payment.dto.KakaoPayReadyResponseDTO;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Component;
+import org.springframework.web.reactive.function.client.WebClient;
+
+@Component
+@RequiredArgsConstructor
+public class KakaoPayClient {
+
+    private final WebClient webClient;
+    private final ObjectMapper objectMapper;
+
+    @Value("${kakao.pay.secret-key}")
+    private String adminKey;
+
+    public KakaoPayReadyResponseDTO requestPayment(KakaoPayReadyRequestDTO request) {
+        return webClient.post()
+                .uri("https://open-api.kakaopay.com/online/v1/payment/ready")
+                .header("Authorization", "SECRET_KEY " + adminKey)
+                .header("Content-Type", "application/json")
+                .bodyValue(request)
+                .retrieve()
+                .bodyToMono(KakaoPayReadyResponseDTO.class)
+                .block();
+    }
+
+    public KakaoPayApproveResponseDTO approvePayment(KakaoPayApproveRequestDTO request) {
+        return webClient.post()
+                .uri("https://open-api.kakaopay.com/online/v1/payment/approve")
+                .header("Authorization", "SECRET_KEY " + adminKey)
+                .header("Content-Type", "application/json")
+                .bodyValue(request)
+                .retrieve()
+                .bodyToMono(KakaoPayApproveResponseDTO.class)
+                .block();
+    }
+}

src/main/java/com/sumte/payment/kakaopay/WebClientConfig.java

@@ -0,0 +1,13 @@
+package com.sumte.payment.kakaopay;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.reactive.function.client.WebClient;
+
+@Configuration
+public class WebClientConfig {
+    @Bean
+    public WebClient webClient() {
+        return WebClient.builder().build();
+    }
+}

src/main/java/com/sumte/payment/service/PaymentService.java

@@ -1,9 +1,10 @@
 package com.sumte.payment.service;
 
+import com.sumte.payment.dto.KakaoPayApproveResponseDTO;
 import com.sumte.payment.dto.PaymentRequestDTO;
 import com.sumte.payment.dto.PaymentResponseDTO;
 
 public interface PaymentService {
     PaymentResponseDTO.CreatePaymentDTO requestPayment(PaymentRequestDTO.CreatePaymentDTO dto);
-    void approvePayment(Long paymentId, String pgToken);
+    KakaoPayApproveResponseDTO approvePayment(Long paymentId, String pgToken);
 }

src/main/java/com/sumte/payment/service/PaymentServiceImpl.java

@@ -1,61 +1,95 @@
-package com.sumte.payment.service;
-
-import com.sumte.apiPayload.code.error.PaymentErrorCode;
-import com.sumte.apiPayload.exception.SumteException;
-import com.sumte.payment.converter.PaymentConverter;
-import com.sumte.payment.dto.PaymentRequestDTO;
-import com.sumte.payment.dto.PaymentResponseDTO;
-import com.sumte.payment.entity.Payment;
-import com.sumte.payment.entity.PaymentStatus;
-import com.sumte.payment.repository.PaymentRepository;
-import com.sumte.reservation.entity.Reservation;
-import com.sumte.reservation.repository.ReservationRepository;
-import lombok.RequiredArgsConstructor;
-import org.springframework.stereotype.Service;
-import org.springframework.transaction.annotation.Transactional;
-
-@Service
-@RequiredArgsConstructor
-public class PaymentServiceImpl implements PaymentService {
-
-    private final ReservationRepository reservationRepository;
-    private final PaymentRepository paymentRepository;
-    private final PaymentTransactionHelper transactionHelper;
-
-    @Override
-    @Transactional
-    public PaymentResponseDTO.CreatePaymentDTO requestPayment(PaymentRequestDTO.CreatePaymentDTO dto) {
-        Reservation reservation = reservationRepository.findById(dto.getReservationId())
-                .orElseThrow(() -> new SumteException(PaymentErrorCode.RESERVATION_NOT_FOUND));
-
-        Payment payment;
-        try {
-            payment = PaymentConverter.toEntity(dto, reservation);
-        } catch (IllegalArgumentException e) {
-            throw new SumteException(PaymentErrorCode.INVALID_PAYMENT_METHOD);
-        }
-        paymentRepository.save(payment);
+    package com.sumte.payment.service;
 
-        String paymentUrl = "https://pay.mock.kakao.com/" + payment.getId();
-        return PaymentConverter.toCreateResponse(payment, paymentUrl);
-    }
+    import com.sumte.apiPayload.code.error.PaymentErrorCode;
+    import com.sumte.apiPayload.exception.SumteException;
+    import com.sumte.payment.converter.PaymentConverter;
+    import com.sumte.payment.dto.*;
+    import com.sumte.payment.entity.Payment;
+    import com.sumte.payment.entity.PaymentStatus;
+    import com.sumte.payment.kakaopay.KakaoPayClient;
+    import com.sumte.payment.repository.PaymentRepository;
+    import com.sumte.reservation.entity.Reservation;
+    import com.sumte.reservation.repository.ReservationRepository;
+    import lombok.RequiredArgsConstructor;
+    import org.springframework.beans.factory.annotation.Value;
+    import org.springframework.stereotype.Service;
+    import org.springframework.transaction.annotation.Transactional;
 
-    @Override
-    @Transactional
-    public void approvePayment(Long paymentId, String pgToken) {
-        Payment payment = paymentRepository.findById(paymentId)
-                .orElseThrow(() -> new SumteException(PaymentErrorCode.PAYMENT_NOT_FOUND));
+    @Service
+    @RequiredArgsConstructor
+    public class PaymentServiceImpl implements PaymentService {
 
-        if (payment.getPaymentStatus() == PaymentStatus.PAID) {
-            throw new SumteException(PaymentErrorCode.ALREADY_APPROVED_PAYMENT);
-        }
+        private final ReservationRepository reservationRepository;
+        private final PaymentRepository paymentRepository;
+        private final PaymentTransactionHelper transactionHelper;
+        private final KakaoPayClient kakaoPayClient;
+
+        @Value("${app.host}")
+        private String appHost;
+
+        @Override
+        @Transactional
+        public PaymentResponseDTO.CreatePaymentDTO requestPayment(PaymentRequestDTO.CreatePaymentDTO dto) {
+            Reservation reservation = reservationRepository.findById(dto.getReservationId())
+                    .orElseThrow(() -> new SumteException(PaymentErrorCode.RESERVATION_NOT_FOUND));
+
+            Payment payment;
+            try {
+                payment = PaymentConverter.toEntity(dto, reservation);
+            } catch (IllegalArgumentException e) {
+                throw new SumteException(PaymentErrorCode.INVALID_PAYMENT_METHOD);
+            }
+            paymentRepository.save(payment);
+
+
+            String itemName = reservation.getRoom().getName();
+            Long totalAmount = reservation.getRoom().getPrice();
+
+            KakaoPayReadyRequestDTO request = KakaoPayReadyRequestDTO.builder()
+                    .cid("TC0ONETIME")
+                    .partner_order_id("reservation_" + reservation.getId())
+                    .partner_user_id("user_" + reservation.getUser().getId())
+                    .item_name(itemName)
+                    .quantity("1")
+                    .total_amount(String.valueOf(totalAmount))
+                    .tax_free_amount("0")
+                    .approval_url(appHost + "/pay/success")
+                    .cancel_url(appHost + "/pay/cancel")
+                    .fail_url(appHost + "/pay/fail")
+                    .build();
 
-        if (pgToken == null || pgToken.isBlank()) {
-            transactionHelper.markPaymentFailed(payment);
-            throw new SumteException(PaymentErrorCode.PG_TOKEN_MISSING);
+            KakaoPayReadyResponseDTO kakaoResponse = kakaoPayClient.requestPayment(request);
+            payment.setTid(kakaoResponse.getTid());
+
+            return PaymentConverter.toCreateResponse(payment, kakaoResponse.getNext_redirect_pc_url());
         }
 
-        payment.markAsPaid();
-    }
+        @Override
+        @Transactional
+        public KakaoPayApproveResponseDTO approvePayment(Long paymentId, String pgToken) {
+            Payment payment = paymentRepository.findById(paymentId)
+                    .orElseThrow(() -> new SumteException(PaymentErrorCode.PAYMENT_NOT_FOUND));
+
+            if (payment.getPaymentStatus() == PaymentStatus.PAID) {
+                throw new SumteException(PaymentErrorCode.ALREADY_APPROVED_PAYMENT);
+            }
+
+            if (pgToken == null || pgToken.isBlank()) {
+                transactionHelper.markPaymentFailed(payment);
+                throw new SumteException(PaymentErrorCode.PG_TOKEN_MISSING);
+            }
 
-}
+            KakaoPayApproveRequestDTO request = KakaoPayApproveRequestDTO.builder()
+                    .cid("TC0ONETIME")
+                    .tid(payment.getTid())
+                    .partner_order_id("reservation_" + payment.getReservation().getId())
+                    .partner_user_id("user_" + payment.getReservation().getUser().getId())
+                    .pg_token(pgToken)
+                    .build();
+
+            KakaoPayApproveResponseDTO response = kakaoPayClient.approvePayment(request);
+            payment.markAsPaid();
+
+            return response;
+        }
+    }