feat: 무료 주문 생성하기 API 구현

src/main/java/com/gdschongik/gdsc/domain/common/vo/Money.java

@@ -34,6 +34,8 @@ private Money(BigDecimal amount) {
         this.amount = amount;
     }
 
+    public static final Money ZERO = Money.from(BigDecimal.ZERO);
+
     public static Money from(BigDecimal amount) {
         validateAmountNotNull(amount);
 

src/main/java/com/gdschongik/gdsc/domain/coupon/domain/Coupon.java

@@ -11,7 +11,6 @@
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
-import java.math.BigDecimal;
 import lombok.AccessLevel;
 import lombok.Builder;
 import lombok.Getter;
@@ -46,7 +45,7 @@ public static Coupon createCoupon(String name, Money discountAmount) {
     // 검증 로직
 
     private static void validateDiscountAmountPositive(Money discountAmount) {
-        if (!discountAmount.isGreaterThan(Money.from(BigDecimal.ZERO))) {
+        if (!discountAmount.isGreaterThan(Money.ZERO)) {
             throw new CustomException(COUPON_DISCOUNT_AMOUNT_NOT_POSITIVE);
         }
     }

src/main/java/com/gdschongik/gdsc/domain/order/api/AdminOrderController.java

@@ -37,15 +37,15 @@ public ResponseEntity<Page<OrderAdminResponse>> getOrders(
     }
 
     @Operation(
-            summary = "완료된 주문 결제정보 조회하기",
-            description = "주문 결제정보를 조회합니다. 토스페이먼츠 API의 결제 정보인 Payment 객체를 반환합니다. 완료된 주문에 대해서만 조회 가능합니다.")
+            summary = "완료된 유료 주문 결제정보 조회하기",
+            description = "주문 결제정보를 조회합니다. 토스페이먼츠 API의 결제 정보인 Payment 객체를 반환합니다. 완료된 유료 주문만 조회할 수 있습니다")
     @GetMapping("/{orderId}")
     public ResponseEntity<PaymentResponse> getCompletedOrderPayment(@PathVariable Long orderId) {
-        var response = orderService.getCompletedOrderPayment(orderId);
+        var response = orderService.getCompletedPaidOrderPayment(orderId);
         return ResponseEntity.ok(response);
     }
 
-    @Operation(summary = "주문 결제 취소하기", description = "주문 상태를 취소로 변경하고 결제를 취소합니다.")
+    @Operation(summary = "주문 결제 취소하기", description = "주문 상태를 취소로 변경하고 결제를 취소합니다. 회비납입상태를 대기로 변경하고, 준회원으로 강등합니다.")
     @PostMapping("/{orderId}/cancel")
     public ResponseEntity<Void> cancelOrder(
             @PathVariable Long orderId, @Valid @RequestBody OrderCancelRequest request) {

src/main/java/com/gdschongik/gdsc/domain/order/api/OnboardingOrderController.java

@@ -28,10 +28,17 @@ public ResponseEntity<Void> createPendingOrder(@Valid @RequestBody OrderCreateRe
         return ResponseEntity.ok().build();
     }
 
-    @Operation(summary = "주문 완료하기", description = "주문을 완료합니다. 요청된 결제는 승인됩니다.")
+    @Operation(summary = "주문 완료", description = "임시 주문을 완료합니다. 요청된 결제는 승인됩니다.")
     @PostMapping("/complete")
     public ResponseEntity<Void> completeOrder(@Valid @RequestBody OrderCompleteRequest request) {
         orderService.completeOrder(request);
         return ResponseEntity.ok().build();
     }
+
+    @Operation(summary = "무료 주문 생성", description = "무료 주문을 생성합니다. 무료 주문은 완료된 상태로 생성됩니다.")
+    @PostMapping("/free")
+    public ResponseEntity<Void> createFreeOrder(@Valid @RequestBody OrderCreateRequest request) {
+        orderService.createFreeOrder(request);
+        return ResponseEntity.ok().build();
+    }
 }

src/main/java/com/gdschongik/gdsc/domain/order/application/OrderService.java

@@ -107,11 +107,12 @@ public Page<OrderAdminResponse> searchOrders(OrderQueryOption queryOption, Pagea
     }
 
     @Transactional(readOnly = true)
-    public PaymentResponse getCompletedOrderPayment(Long orderId) {
+    public PaymentResponse getCompletedPaidOrderPayment(Long orderId) {
         Order order = orderRepository
                 .findById(orderId)
                 .filter(Order::isCompleted)
-                .orElseThrow(() -> new CustomException(ORDER_COMPLETED_NOT_FOUND));
+                .filter(o -> !o.isFree())
+                .orElseThrow(() -> new CustomException(ORDER_COMPLETED_PAID_NOT_FOUND));
 
         return paymentClient.getPayment(order.getPaymentKey());
     }
@@ -141,4 +142,29 @@ private ZonedDateTime getCanceledAt(PaymentResponse response) {
     private Optional<ZonedDateTime> findLatestCancelDate(List<PaymentResponse.CancelDto> cancels) {
         return cancels.stream().map(PaymentResponse.CancelDto::canceledAt).max(ZonedDateTime::compareTo);
     }
+
+    @Transactional
+    public void createFreeOrder(OrderCreateRequest request) {
+        Membership membership = membershipRepository
+                .findById(request.membershipId())
+                .orElseThrow(() -> new CustomException(MEMBERSHIP_NOT_FOUND));
+
+        Optional<IssuedCoupon> issuedCoupon =
+                Optional.ofNullable(request.issuedCouponId()).map(this::getIssuedCoupon);
+
+        MoneyInfo moneyInfo = MoneyInfo.of(
+                Money.from(request.totalAmount()),
+                Money.from(request.discountAmount()),
+                Money.from(request.finalPaymentAmount()));
+
+        Member currentMember = memberUtil.getCurrentMember();
+
+        orderValidator.validateFreeOrderCreate(membership, issuedCoupon, currentMember);
+
+        Order order = Order.createFree(request.orderNanoId(), membership, issuedCoupon.orElse(null), moneyInfo);
+
+        orderRepository.save(order);
+
+        log.info("[OrderService] 무료 주문 생성: orderId={}", order.getId());
+    }
 }

src/main/java/com/gdschongik/gdsc/domain/order/domain/MoneyInfo.java

@@ -58,4 +58,8 @@ private static void validateFinalPaymentAmount(Money totalAmount, Money discount
             throw new CustomException(ErrorCode.ORDER_FINAL_PAYMENT_AMOUNT_MISMATCH);
         }
     }
+
+    public boolean isFree() {
+        return finalPaymentAmount.equals(Money.ZERO);
+    }
 }

src/main/java/com/gdschongik/gdsc/domain/order/domain/Order.java

@@ -98,6 +98,26 @@ public static Order createPending(
                 .build();
     }
 
+    public static Order createFree(
+            String nanoId, Membership membership, @Nullable IssuedCoupon issuedCoupon, MoneyInfo moneyInfo) {
+        validateFreeOrder(moneyInfo);
+        return Order.builder()
+                .status(OrderStatus.COMPLETED)
+                .nanoId(nanoId)
+                .memberId(membership.getMember().getId())
+                .membershipId(membership.getId())
+                .recruitmentRoundId(membership.getRecruitmentRound().getId())
+                .issuedCouponId(issuedCoupon != null ? issuedCoupon.getId() : null)
+                .moneyInfo(moneyInfo)
+                .build();
+    }
+
+    private static void validateFreeOrder(MoneyInfo moneyInfo) {
+        if (!moneyInfo.isFree()) {
+            throw new CustomException(ORDER_FREE_FINAL_PAYMENT_NOT_ZERO);
+        }
+    }
+
     // 데이터 변경 로직
 
     /**
@@ -119,6 +139,7 @@ public void complete(String paymentKey, ZonedDateTime approvedAt) {
      * 상태 변경 및 취소 시각을 저장하며, 예외를 발생시키지 않도록 외부 취소 요청 전에 validateCancelable을 호출합니다.
      */
     public void cancel(ZonedDateTime canceledAt) {
+        // TODO: 취소 이벤트 발행을 통해 멤버십 및 멤버 상태에 대한 변경 로직 추가
         validateCancelable();
         this.status = OrderStatus.CANCELED;
         this.canceledAt = canceledAt;
@@ -128,11 +149,19 @@ public void validateCancelable() {
         if (status != OrderStatus.COMPLETED) {
             throw new CustomException(ORDER_CANCEL_NOT_COMPLETED);
         }
+
+        if (isFree()) {
+            throw new CustomException(ORDER_CANCEL_FREE_ORDER);
+        }
     }
 
     // 데이터 조회 로직
 
     public boolean isCompleted() {
         return status == OrderStatus.COMPLETED;
     }
+
+    public boolean isFree() {
+        return moneyInfo.isFree();
+    }
 }

src/main/java/com/gdschongik/gdsc/domain/order/domain/OrderValidator.java

@@ -10,7 +10,6 @@
 import com.gdschongik.gdsc.global.annotation.DomainService;
 import com.gdschongik.gdsc.global.exception.CustomException;
 import jakarta.annotation.Nullable;
-import java.math.BigDecimal;
 import java.util.Optional;
 
 @DomainService
@@ -68,7 +67,7 @@ private void validateIssuedCouponOwnership(IssuedCoupon issuedCoupon, Member cur
     }
 
     private void validateDiscountAmountZero(Money discountAmount) {
-        if (!discountAmount.equals(Money.from(BigDecimal.ZERO))) {
+        if (!discountAmount.equals(Money.ZERO)) {
             throw new CustomException(ORDER_DISCOUNT_AMOUNT_NOT_ZERO);
         }
     }
@@ -99,4 +98,35 @@ public void validateCompleteOrder(
             throw new CustomException(ORDER_COMPLETE_AMOUNT_MISMATCH);
         }
     }
+
+    public void validateFreeOrderCreate(
+            Membership membership, Optional<IssuedCoupon> optionalIssuedCoupon, Member currentMember) {
+        // TODO: 공통 로직으로 추출
+
+        // 멤버십 관련 검증
+
+        if (!membership.getMember().getId().equals(currentMember.getId())) {
+            throw new CustomException(ORDER_MEMBERSHIP_MEMBER_MISMATCH);
+        }
+
+        if (membership.getRegularRequirement().isPaymentSatisfied()) {
+            throw new CustomException(ORDER_MEMBERSHIP_ALREADY_PAID);
+        }
+
+        // 리쿠르팅 관련 검증
+
+        RecruitmentRound recruitmentRound = membership.getRecruitmentRound();
+
+        if (!recruitmentRound.isOpen()) {
+            throw new CustomException(ORDER_RECRUITMENT_PERIOD_INVALID);
+        }
+
+        // 발급쿠폰 관련 검증
+
+        if (optionalIssuedCoupon.isPresent()) {
+            var issuedCoupon = optionalIssuedCoupon.get();
+            validateIssuedCouponOwnership(issuedCoupon, currentMember);
+            issuedCoupon.validateUsable();
+        }
+    }
 }

src/main/java/com/gdschongik/gdsc/global/exception/ErrorCode.java

@@ -117,10 +117,12 @@ public enum ErrorCode {
     ORDER_ALREADY_COMPLETED(HttpStatus.CONFLICT, "이미 완료된 주문입니다."),
     ORDER_COMPLETE_AMOUNT_MISMATCH(HttpStatus.CONFLICT, "주문 최종결제금액이 주문완료요청의 결제금액과 일치하지 않습니다."),
     ORDER_COMPLETE_MEMBER_MISMATCH(HttpStatus.CONFLICT, "주문자와 현재 로그인한 멤버가 일치하지 않습니다."),
-    ORDER_COMPLETED_NOT_FOUND(HttpStatus.NOT_FOUND, "존재하지 않는 주문이거나, 완료되지 않은 주문입니다."),
+    ORDER_COMPLETED_PAID_NOT_FOUND(HttpStatus.NOT_FOUND, "존재하지 않는 주문이거나, 완료되지 않은 유료 주문입니다."),
     ORDER_CANCEL_NOT_COMPLETED(HttpStatus.CONFLICT, "완료되지 않은 주문은 취소할 수 없습니다."),
+    ORDER_CANCEL_FREE_ORDER(HttpStatus.CONFLICT, "무료 주문은 취소할 수 없습니다."),
     ORDER_CANCEL_RESPONSE_NOT_FOUND(
             HttpStatus.INTERNAL_SERVER_ERROR, "주문 결제가 취소되었지만, 응답에 취소 정보가 존재하지 않습니다. 관리자에게 문의 바랍니다."),
+    ORDER_FREE_FINAL_PAYMENT_NOT_ZERO(HttpStatus.CONFLICT, "무료 주문의 최종결제금액은 0원이어야 합니다."),
 
     // Order - MoneyInfo
     ORDER_FINAL_PAYMENT_AMOUNT_MISMATCH(HttpStatus.CONFLICT, "주문 최종결제금액은 주문총액에서 할인금액을 뺀 값이어야 합니다."),