[FEAT] 카카오페이 결제 구현 (#71)

src/main/java/com/brainpix/api/code/error/KakaoPayErrorCode.java

@@ -0,0 +1,22 @@
+package com.brainpix.api.code.error;
+
+import org.springframework.http.HttpStatus;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@Getter
+@RequiredArgsConstructor
+public enum KakaoPayErrorCode implements ErrorCode {
+
+	// 400 Bad Request - 잘못된 요청
+	IDEA_OWNER_PURCHASE_INVALID(HttpStatus.BAD_REQUEST, "KAKAOPAY400", "글 작성자는 구매할 수 없습니다."),
+	QUANTITY_INVALID(HttpStatus.BAD_REQUEST, "KAKAOPAY400", "구매 수량은 재고를 초과할 수 없습니다."),
+
+	// 500 Internal Server Error - 서버 내부 오류
+	API_RESPONSE_ERROR(HttpStatus.INTERNAL_SERVER_ERROR, "KAKAOPAY500", "카카오페이 API 호출 중 오류가 발생하였습니다.");
+
+	private final HttpStatus httpStatus;
+	private final String code;
+	private final String message;
+}

src/main/java/com/brainpix/joining/entity/quantity/BaseQuantity.java

@@ -21,4 +21,12 @@ public BaseQuantity(Long totalQuantity, Long occupiedQuantity) {
 		this.totalQuantity = totalQuantity;
 		this.occupiedQuantity = occupiedQuantity;
 	}
+
+	public Long getRemainingQuantity() {
+		return this.totalQuantity - this.occupiedQuantity;
+	}
+
+	public void increaseOccupiedQuantity(Long quantity) {
+		this.occupiedQuantity += quantity;
+	}
 }

src/main/java/com/brainpix/joining/repository/IdeaMarketPurchasingRepository.java

@@ -12,8 +12,7 @@
 import com.brainpix.user.entity.User;
 
 @Repository
-public interface IdeaMarketPurchasingRepository
-	extends JpaRepository<IdeaMarketPurchasing, Long> {
+public interface IdeaMarketPurchasingRepository extends JpaRepository<IdeaMarketPurchasing, Long> {
 	Page<IdeaMarketPurchasing> findByBuyer(User buyer, Pageable pageable);
 
 	List<IdeaMarketPurchasing> findByIdeaMarket(IdeaMarket ideaMarket);

src/main/java/com/brainpix/kakaopay/api_client/KakaoPayApiClient.java

@@ -0,0 +1,110 @@
+package com.brainpix.kakaopay.api_client;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Component;
+import org.springframework.web.client.RestTemplate;
+
+import com.brainpix.kakaopay.dto.KakaoPayApproveDto;
+import com.brainpix.kakaopay.dto.KakaoPayReadyDto;
+import com.brainpix.kakaopay.entity.KakaoPaymentData;
+import com.brainpix.post.entity.idea_market.IdeaMarket;
+import com.brainpix.user.entity.User;
+
+@Component
+public class KakaoPayApiClient {
+
+	private final RestTemplate restTemplate = new RestTemplate();
+
+	@Value("${kakao.pay.ready-url}")
+	private String READY_URL;
+	@Value("${kakao.pay.approve-url}")
+	private String APPROVE_URL;
+
+	@Value("${kakao.pay.cid}")
+	private String cid;        // TC0ONETIME (테스트용 가맹점 cid)
+	@Value("${kakao.pay.secret-key}")
+	private String secretKey;    // secret-key(dev) 값 (테스트용 시크릿 값)
+
+	// 카카오페이 결제 준비 API
+	public KakaoPayReadyDto.KakaoApiResponse requestPaymentReady(
+		KakaoPayReadyDto.Parameter parameter, String orderId, User buyer, IdeaMarket ideaMarket) {
+
+		Map<String, String> parameters = getReadyParams(parameter, orderId, buyer, ideaMarket);
+		HttpHeaders headers = getHeaders();
+
+		HttpEntity<Map<String, String>> requestEntity = new HttpEntity<>(parameters, headers);
+
+		ResponseEntity<KakaoPayReadyDto.KakaoApiResponse> response = restTemplate.postForEntity(
+			READY_URL, requestEntity, KakaoPayReadyDto.KakaoApiResponse.class
+		);
+
+		return response.getBody();
+	}
+
+	// 카카오페이 결제 승인 API
+	public KakaoPayApproveDto.KakaoApiResponse requestPaymentApprove(
+		KakaoPayApproveDto.Parameter parameter, KakaoPaymentData kakaoPaymentData) {
+
+		Map<String, String> parameters = getApproveParams(parameter, kakaoPaymentData);
+		HttpHeaders headers = getHeaders();
+
+		HttpEntity<Map<String, String>> requestEntity = new HttpEntity<>(parameters, headers);
+
+		ResponseEntity<KakaoPayApproveDto.KakaoApiResponse> response = restTemplate.postForEntity(
+			APPROVE_URL, requestEntity, KakaoPayApproveDto.KakaoApiResponse.class
+		);
+
+		return response.getBody();
+	}
+
+	// 결제 준비 파라미터 생성
+	private Map<String, String> getReadyParams(
+		KakaoPayReadyDto.Parameter parameter, String orderId, User buyer, IdeaMarket ideaMarket) {
+
+		Map<String, String> params = new HashMap<>();
+
+		params.put("cid", cid);
+		params.put("partner_order_id", orderId);
+		params.put("partner_user_id", String.valueOf(buyer.getId()));
+		params.put("item_name", ideaMarket.getTitle());
+		params.put("quantity", String.valueOf(parameter.getQuantity()));
+		params.put("total_amount", String.valueOf(parameter.getTotalPrice()));
+		params.put("tax_free_amount", "0");
+		params.put("vat_amount", String.valueOf(parameter.getVat()));
+		params.put("approval_url",
+			"https://www.brainpix.net/purchase/approve?ideaId=" + ideaMarket.getId() + "&orderId=" + orderId);
+		params.put("cancel_url", "https://www.brainpix.net/purchase/cancel?ideaId=" + ideaMarket.getId());
+		params.put("fail_url", "https://www.brainpix.net/purchase/fail?ideaId=" + ideaMarket.getId());
+
+		return params;
+	}
+
+	// 결제 승인 파라미터 생성
+	private Map<String, String> getApproveParams(KakaoPayApproveDto.Parameter parameter,
+		KakaoPaymentData kakaoPaymentData) {
+
+		Map<String, String> params = new HashMap<>();
+
+		params.put("cid", cid);
+		params.put("tid", kakaoPaymentData.getTid());
+		params.put("partner_order_id", parameter.getOrderId());
+		params.put("partner_user_id", String.valueOf(kakaoPaymentData.getBuyer().getId()));
+		params.put("pg_token", parameter.getPgToken());
+
+		return params;
+	}
+
+	// API 호출에 필요한 헤더 생성
+	private HttpHeaders getHeaders() {
+		HttpHeaders headers = new HttpHeaders();
+		headers.set("Authorization", "SECRET_KEY " + secretKey);
+		headers.set("Content-type", "application/json");
+		return headers;
+	}
+}

src/main/java/com/brainpix/kakaopay/controller/KakaoPayController.java

@@ -0,0 +1,51 @@
+package com.brainpix.kakaopay.controller;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.brainpix.api.ApiResponse;
+import com.brainpix.kakaopay.converter.KakaoPayApproveDtoConverter;
+import com.brainpix.kakaopay.converter.KakaoPayReadyDtoConverter;
+import com.brainpix.kakaopay.dto.KakaoPayApproveDto;
+import com.brainpix.kakaopay.dto.KakaoPayReadyDto;
+import com.brainpix.kakaopay.service.KakaoPayFacadeService;
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
+@Slf4j
+@RestController
+@RequestMapping("/kakao-pay")
+@RequiredArgsConstructor
+@Tag(name = "카카오페이 아이디어 결제 API", description = "아이디어를 카카오페이로 결제하는 API 입니다.<br>결제 과정 : 결제 준비 API 호출 -> 리다이렉트된 사용자의 결제 진행 -> 결제 승인 API 호출")
+public class KakaoPayController {
+
+	private final KakaoPayFacadeService kakaoPayService;
+
+	@Operation(summary = "결제 준비 API", description = "아이디어 식별자, 판매자 식별자, 상품 수량, 총 결제금액(vat 포함), vat를 json 본문으로 입력받아 카카오페이 쪽에 결제 정보를 생성합니다.<br>사용자를 결제 화면으로 이동시킬 수 있도록 리다이렉트 url과 주문 번호가 응답값으로 제공됩니다.<br>주문 번호는 이후 승인 단계에서 pgToken과 함께 전달해주시면 됩니다.")
+	@PostMapping("/ready")
+	public ResponseEntity<ApiResponse<KakaoPayReadyDto.Response>> kakaoPayReady(@RequestParam Long userId,
+		@RequestBody KakaoPayReadyDto.Request request) {
+		log.info("카카오페이 결제 준비 API 호출");
+		KakaoPayReadyDto.Parameter parameter = KakaoPayReadyDtoConverter.toParameter(userId, request);
+		KakaoPayReadyDto.Response response = kakaoPayService.kakaoPayReady(parameter);
+		return ResponseEntity.ok(ApiResponse.success(response));
+	}
+
+	@Operation(summary = "결제 승인 API", description = "pgToken과 주문 번호를 json 본문으로 입력받아 최종 승인을 처리합니다.")
+	@PostMapping("/approve")
+	public ResponseEntity<ApiResponse<KakaoPayApproveDto.Response>> kakaoPayApprove(
+		@RequestParam Long userId,
+		@RequestBody KakaoPayApproveDto.Request request) {
+		log.info("카카오페이 결제 최종 승인 API 호출");
+		KakaoPayApproveDto.Parameter parameter = KakaoPayApproveDtoConverter.toParameter(userId, request);
+		KakaoPayApproveDto.Response response = kakaoPayService.kakaoPayApprove(parameter);
+		return ResponseEntity.ok(ApiResponse.success(response));
+	}
+}

src/main/java/com/brainpix/kakaopay/converter/KakaoPayApproveDtoConverter.java

@@ -0,0 +1,42 @@
+package com.brainpix.kakaopay.converter;
+
+import com.brainpix.joining.entity.purchasing.IdeaMarketPurchasing;
+import com.brainpix.joining.entity.purchasing.Payment;
+import com.brainpix.joining.entity.quantity.PaymentDuration;
+import com.brainpix.kakaopay.dto.KakaoPayApproveDto;
+import com.brainpix.post.entity.idea_market.IdeaMarket;
+import com.brainpix.user.entity.User;
+
+public class KakaoPayApproveDtoConverter {
+
+	public static KakaoPayApproveDto.Parameter toParameter(Long userId, KakaoPayApproveDto.Request request) {
+
+		return KakaoPayApproveDto.Parameter.builder()
+			.userId(userId)
+			.orderId(request.getOrderId())
+			.pgToken(request.getPgToken())
+			.build();
+	}
+
+	public static IdeaMarketPurchasing toIdeaMarketPurchasing(KakaoPayApproveDto.KakaoApiResponse kakaoApiResponse,
+		User user,
+		IdeaMarket ideaMarket, PaymentDuration paymentDuration) {
+
+		return IdeaMarketPurchasing.builder()
+			.buyer(user)
+			.ideaMarket(ideaMarket)
+			.paymentDuration(paymentDuration)
+			.price(kakaoApiResponse.getAmount().getTotal())
+			.vat(kakaoApiResponse.getAmount().getVat())
+			.quantity(kakaoApiResponse.getQuantity())
+			.payment(Payment.KAKAO_PAY)
+			.build();
+	}
+
+	public static KakaoPayApproveDto.Response toResponse(IdeaMarketPurchasing ideaMarketPurchasing) {
+
+		return KakaoPayApproveDto.Response.builder()
+			.ideaMarketPurchasingId(ideaMarketPurchasing.getId())
+			.build();
+	}
+}

src/main/java/com/brainpix/kakaopay/converter/KakaoPayReadyDtoConverter.java

@@ -0,0 +1,43 @@
+package com.brainpix.kakaopay.converter;
+
+import com.brainpix.kakaopay.dto.KakaoPayReadyDto;
+import com.brainpix.kakaopay.entity.KakaoPaymentData;
+import com.brainpix.post.entity.idea_market.IdeaMarket;
+import com.brainpix.user.entity.User;
+
+public class KakaoPayReadyDtoConverter {
+
+	public static KakaoPayReadyDto.Parameter toParameter(Long userId, KakaoPayReadyDto.Request request) {
+
+		return KakaoPayReadyDto.Parameter.builder()
+			.buyerId(userId)
+			.sellerId(request.getSellerId())
+			.ideaId(request.getIdeaId())
+			.quantity(request.getQuantity())
+			.totalPrice(request.getTotalPrice())
+			.vat(request.getVat())
+			.build();
+	}
+
+	public static KakaoPayReadyDto.Response toResponse(KakaoPayReadyDto.KakaoApiResponse kakaoApiResponse,
+		String orderId) {
+
+		return KakaoPayReadyDto.Response.builder()
+			.nextRedirectPcUrl(kakaoApiResponse.getNext_redirect_pc_url())
+			.build();
+	}
+
+	public static KakaoPaymentData toKakaoPaymentData(KakaoPayReadyDto.KakaoApiResponse kakaoApiResponse,
+		KakaoPayReadyDto.Parameter parameter,
+		String orderId, User buyer,
+		IdeaMarket ideaMarket) {
+
+		return KakaoPaymentData.builder()
+			.tid(kakaoApiResponse.getTid())
+			.quantity(parameter.getQuantity())
+			.orderId(orderId)
+			.buyer(buyer)
+			.ideaMarket(ideaMarket)
+			.build();
+	}
+}

src/main/java/com/brainpix/kakaopay/dto/KakaoPayApproveDto.java

@@ -0,0 +1,57 @@
+package com.brainpix.kakaopay.dto;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+public class KakaoPayApproveDto {
+
+	@NoArgsConstructor
+	@Getter
+	public static class Request {
+		@NotBlank(message = "토큰을 입력해주세요.")
+		private String pgToken;    // 결제 최종 완료를 위한 토큰
+		@NotBlank(message = "주문 번호를 입력해주세요.")
+		private String orderId;    // 주문 번호 (세션에서 결제 정보 탐색 Key)
+		@NotNull(message = "아이디어 게시글 ID를 입력해주세요.")
+		private Long ideaId;        // 아이디어 ID
+	}
+
+	@Getter
+	@Builder
+	public static class Parameter {
+		private Long userId;    // 유저 ID
+		private String orderId;    // 주문 번호 (결제 정보 탐색 Key)
+		private String pgToken;    // 결제 최종 완료를 위한 토큰
+		private Long ideaId;    // 아이디어 ID
+	}
+
+	@Getter
+	@Builder
+	public static class KakaoApiResponse {
+		private String aid;    // 요청 고유 번호
+		private String tid;    // 결제 고유 번호
+		private String cid;    // 가맹점 코드
+		private String partner_order_id;    // 주문 번호 (DB에 저장)
+		private String partner_user_id;    // 구매자 ID
+		private String item_name;    // 상품 이름
+		private Long quantity;    // 상품 수량
+		private Amount amount;    // 결제 금액 관련
+		private String approved_at;    // 결제 승인 시각
+	}
+
+	@Getter
+	@Builder
+	public static class Amount {
+		private Long total;    // 총 결제 금액
+		private Long vat;    // 부가세 금액
+	}
+
+	@Getter
+	@Builder
+	public static class Response {
+		private Long ideaMarketPurchasingId;
+	}
+}