fix(订单): 修复折扣计算问题并添加四舍五入处理

统一处理百分比和系数两种折扣输入方式，增加边界保护
在金额计算中使用math.Round进行四舍五入处理
添加相关单元测试确保计算准确性

internal/logic/public/portal/prePurchaseOrderLogic.go

@@ -3,6 +3,7 @@ package portal
 import (
 	"context"
 	"encoding/json"
+	"math"
 
 	"github.com/perfect-panel/server/pkg/tool"
 
@@ -43,7 +44,7 @@ func (l *PrePurchaseOrderLogic) PrePurchaseOrder(req *types.PrePurchaseOrderRequ
 		discount = getDiscount(dis, req.Quantity)
 	}
 	price := sub.UnitPrice * req.Quantity
-	amount := int64(float64(price) * discount)
+    amount := int64(math.Round(float64(price) * discount))
 	discountAmount := price - amount
 	var coupon int64
 	if req.Coupon != "" {

internal/logic/public/portal/purchaseCheckoutLogic.go

@@ -3,6 +3,7 @@ package portal
 import (
 	"context"
 	"encoding/json"
+	"math"
 	"strconv"
 	"time"
 
@@ -184,7 +185,7 @@ func (l *PurchaseCheckoutLogic) alipayF2fPayment(pay *payment.Payment, info *ord
 		l.Errorw("[PurchaseCheckout] queryExchangeRate error", logger.Field("error", err.Error()))
 		return "", errors.Wrapf(xerr.NewErrCode(xerr.ERROR), "queryExchangeRate error: %s", err.Error())
 	}
-	convertAmount := int64(amount * 100) // Convert to cents for API
+    convertAmount := int64(math.Round(amount * 100)) // Convert to cents for API
 
 	// Create pre-payment trade and generate QR code
 	QRCode, err := client.PreCreateTrade(l.ctx, alipay.Order{
@@ -222,7 +223,7 @@ func (l *PurchaseCheckoutLogic) stripePayment(config string, info *order.Order,
 		l.Errorw("[PurchaseCheckout] queryExchangeRate error", logger.Field("error", err.Error()))
 		return nil, errors.Wrapf(xerr.NewErrCode(xerr.ERROR), "queryExchangeRate error: %s", err.Error())
 	}
-	convertAmount := int64(amount * 100) // Convert to cents for Stripe API
+    convertAmount := int64(math.Round(amount * 100)) // Convert to cents for Stripe API
 
 	// Create Stripe payment sheet for client-side processing
 	result, err := client.CreatePaymentSheet(&stripe.Order{

internal/logic/public/portal/purchaseLogic.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"math"
 	"time"
 
 	"github.com/perfect-panel/server/internal/model/order"
@@ -67,7 +68,7 @@ func (l *PurchaseLogic) Purchase(req *types.PortalPurchaseRequest) (resp *types.
 	}
 	price := sub.UnitPrice * req.Quantity
 	// discount amount
-	amount := int64(float64(price) * discount)
+	amount := int64(math.Round(float64(price) * discount))
 	discountAmount := price - amount
 
 	var couponAmount int64 = 0

internal/logic/public/portal/tool.go

@@ -1,25 +1,33 @@
 package portal
 
 import (
+	"math"
+
 	"github.com/perfect-panel/server/internal/model/coupon"
 	"github.com/perfect-panel/server/internal/model/payment"
 	"github.com/perfect-panel/server/internal/types"
 )
 
 func getDiscount(discounts []types.SubscribeDiscount, inputMonths int64) float64 {
-	var finalDiscount int64 = 100
-
-	for _, discount := range discounts {
-		if inputMonths >= discount.Quantity && int64(discount.Discount*100) < finalDiscount {
-			finalDiscount = int64(discount.Discount * 100)
+	final := 1.0
+	for _, d := range discounts {
+		val := d.Discount
+		if val > 1 && val <= 100 {
+			val = val / 100.0
+		}
+		if val < 0 {
+			val = 0
+		}
+		if inputMonths >= d.Quantity && val < final {
+			final = val
 		}
 	}
-	return float64(finalDiscount) / float64(100)
+	return final
 }
 
 func calculateCoupon(amount int64, couponInfo *coupon.Coupon) int64 {
 	if couponInfo.Type == 1 {
-		return int64(float64(amount) * (float64(couponInfo.Discount) / float64(100)))
+		return int64(math.Round(float64(amount) * (float64(couponInfo.Discount) / float64(100))))
 	} else {
 		return min(couponInfo.Discount, amount)
 	}
@@ -39,5 +47,5 @@ func calculateFee(amount int64, config *payment.Payment) int64 {
 	case 3:
 		fee = float64(amount)*(float64(config.FeePercent)/float64(100)) + float64(config.FeeAmount)
 	}
-	return int64(fee)
+	return int64(math.Round(fee))
 }

internal/logic/public/portal/tool_test.go

@@ -0,0 +1,23 @@
+package portal
+
+import (
+    "testing"
+    "github.com/perfect-panel/server/internal/types"
+)
+
+func TestGetDiscount_Coefficient(t *testing.T) {
+    discounts := []types.SubscribeDiscount{{Quantity: 7, Discount: 0.9}}
+    got := getDiscount(discounts, 7)
+    if got != 0.9 {
+        t.Fatalf("expected 0.9, got %v", got)
+    }
+}
+
+func TestGetDiscount_Percentage(t *testing.T) {
+    discounts := []types.SubscribeDiscount{{Quantity: 7, Discount: 90}}
+    got := getDiscount(discounts, 7)
+    if got != 0.9 {
+        t.Fatalf("expected 0.9 from 90%%, got %v", got)
+    }
+}
+