affiliate_dash/backend/internal/service/fulfillment_order.go

package service

import (
	"errors"
	"math"
	"strings"

	"affiliate_dash/internal/model"
	"affiliate_dash/internal/pkg/timeutil"

	"github.com/google/uuid"
)

func newFulfillmentOrderNo() string {
	return "FO" + timeutil.Now().Format(timeutil.OrderNoLayout) + strings.ReplaceAll(uuid.NewString()[:12], "-", "")
}

func newTestFulfillmentOrderNo() string {
	return "O" + timeutil.Now().Format(timeutil.OrderNoLayout) + strings.ReplaceAll(uuid.NewString()[:12], "-", "")
}

// calculateServiceFee 按"百分比或固定"二选一计算手续费：
//   - feeType=rate：按 baseAmount * feeRateBP / 10000 计算
//   - feeType=fixed：直接取 feeFixedAmount
//
// 二者互斥，不会叠加。
func calculateServiceFee(baseAmount int64, feeType string, feeRateBP, feeFixedAmount int64) (int64, error) {
	if baseAmount < 0 || feeRateBP < 0 || feeFixedAmount < 0 {
		return 0, errors.New("订单金额或手续费配置无效")
	}
	switch feeType {
	case model.FeeTypeFixed:
		return feeFixedAmount, nil
	case model.FeeTypeRate, "":
		if feeRateBP > 10000 {
			return 0, errors.New("手续费比例不能超过 10000 BP")
		}
		if feeRateBP > 0 && baseAmount > math.MaxInt64/feeRateBP {
			return 0, errors.New("手续费金额超出范围")
		}
		return baseAmount * feeRateBP / 10000, nil
	default:
		return 0, errors.New("无效的手续费类型")
	}
}