修复(#79): 合并internal并适配数量配价

Co-authored-by: multica-agent <github@multica.ai>

internal/logic/public/order/promoPricing.go

@@ -0,0 +1,62 @@
+package order
+
+import (
+	"context"
+	"math"
+
+	commonLogic "github.com/perfect-panel/server/internal/logic/common"
+	"github.com/perfect-panel/server/internal/svc"
+	"github.com/perfect-panel/server/internal/types"
+)
+
+type orderPriceResult struct {
+	OriginalPrice  int64
+	PayableBase    int64
+	DiscountAmount int64
+	PromoRuleId    int64
+	PromoDiscount  int64
+	PromoPrice     int64
+}
+
+func calculatePurchasePrice(
+	ctx context.Context,
+	svcCtx *svc.ServiceContext,
+	userID int64,
+	subscribeID int64,
+	unitPrice int64,
+	quantity int64,
+	discounts []types.SubscribeDiscount,
+	eligibleForDiscount bool,
+	allowPromo bool,
+) (*orderPriceResult, error) {
+	originalPrice := unitPrice * quantity
+	result := &orderPriceResult{
+		OriginalPrice: originalPrice,
+		PayableBase:   originalPrice,
+	}
+
+	if allowPromo {
+		promoResult, err := commonLogic.EvaluatePromo(ctx, svcCtx, userID, subscribeID, quantity)
+		if err != nil {
+			return nil, err
+		}
+		if promoResult != nil && promoResult.Eligible && promoResult.PromoPrice < unitPrice {
+			result.PayableBase = promoResult.PromoPrice * quantity
+			result.PromoRuleId = promoResult.RuleID
+			result.PromoDiscount = originalPrice - result.PayableBase
+			result.PromoPrice = promoResult.PromoPrice
+			if result.PromoDiscount < 0 {
+				result.PromoDiscount = 0
+			}
+			return result, nil
+		}
+	}
+
+	discount := float64(1)
+	if len(discounts) > 0 {
+		discount = getDiscount(discounts, quantity, eligibleForDiscount)
+	}
+	result.PayableBase = int64(math.Round(float64(originalPrice) * discount))
+	result.DiscountAmount = originalPrice - result.PayableBase
+	return result, nil
+}