fix: calculate payment result amount

Author: KGESH

src/infra/payment/payment.service.ts

@@ -49,6 +49,11 @@ export class PaymentService {
     frontendAmount: number | string;
     calculatedBackendAmount: number | string;
   }): void {
+    this.logger.log(`[Payment Verification]`, {
+      pgAmount,
+      frontendAmount,
+      calculatedBackendAmount,
+    });
     if (!decimal.isSame(pgAmount, frontendAmount)) {
       throw new Error(
         `Payment amount mismatch. Reserved: ${frontendAmount} | Amount: ${pgAmount}`,

src/infra/payment/portone-api.types.ts

@@ -23,15 +23,17 @@ export type PortonePaymentResult = {
  * https://developers.portone.io/api/rest-v2/payment?v=v2#post%20%2Fpayments%2F%7BpaymentId%7D%2Fcancel
  */
 export type PortoneSucceededPaymentCancellation = {
-  status: 'SUCCEEDED' | 'FAILED' | 'REQUESTED';
-  id: string;
-  pgCancellationId?: string;
-  reason: string;
-  totalAmount: number;
-  taxFreeAmount: number;
-  vatAmount: number;
-  easyPayDiscountAmount?: number;
-  cancelledAt?: string;
-  requestedAt: string;
-  receiptUrl?: string; // 취소 영수증 URL. status 가 SUCCEEDED 일 때만 존재.
+  cancellation: {
+    status: 'SUCCEEDED' | 'FAILED' | 'REQUESTED';
+    id: string;
+    pgCancellationId?: string;
+    reason: string;
+    totalAmount: number;
+    taxFreeAmount: number;
+    vatAmount: number;
+    easyPayDiscountAmount?: number;
+    cancelledAt?: string;
+    requestedAt: string;
+    receiptUrl?: string; // 취소 영수증 URL. status 가 SUCCEEDED 일 때만 존재.
+  };
 };

src/shared/utils/decimal.ts

@@ -47,3 +47,13 @@ export const divide = (a: number | string, b: number | string): Price => {
   const y = new BigNumber(b);
   return typia.assert<Price>(x.dividedBy(y).toString());
 };
+
+export const floor = (a: number | string): Price => {
+  const x = new BigNumber(a);
+  return typia.assert<Price>(x.integerValue(BigNumber.ROUND_FLOOR).toString());
+};
+
+export const ceil = (a: number | string): Price => {
+  const x = new BigNumber(a);
+  return typia.assert<Price>(x.integerValue(BigNumber.ROUND_CEIL).toString());
+};

src/v1/order/course/course-order-purchase.service.ts

@@ -168,6 +168,7 @@ export class CourseOrderPurchaseService {
       'pricing' | 'discount'
     >,
     coupon: ICoupon | null,
+    rounding: 'floor' | 'ceil' = 'floor',
   ): Price {
     const { pricing, discount } = product;
     let calculatedAmount = pricing.amount;
@@ -186,6 +187,13 @@ export class CourseOrderPurchaseService {
     }
 
     if (!coupon) {
+      // Apply rounding if necessary
+      if (rounding === 'floor') {
+        calculatedAmount = decimal.floor(calculatedAmount);
+      } else if (rounding === 'ceil') {
+        calculatedAmount = decimal.ceil(calculatedAmount);
+      }
+
       return calculatedAmount;
     }
 
@@ -223,6 +231,13 @@ export class CourseOrderPurchaseService {
       calculatedAmount = '0';
     }
 
+    // Apply rounding if necessary
+    if (rounding === 'floor') {
+      calculatedAmount = decimal.floor(calculatedAmount);
+    } else if (rounding === 'ceil') {
+      calculatedAmount = decimal.ceil(calculatedAmount);
+    }
+
     return calculatedAmount;
   }