healthapp/backend/healthapi/internal/logic/preview_order_logic.go

package logic

import (
	"context"

	"healthapi/internal/model"
	"healthapi/internal/svc"
	"healthapi/internal/types"
	"healthapi/pkg/errorx"

	"github.com/zeromicro/go-zero/core/logx"
)

type PreviewOrderLogic struct {
	logx.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewPreviewOrderLogic(ctx context.Context, svcCtx *svc.ServiceContext) *PreviewOrderLogic {
	return &PreviewOrderLogic{
		Logger: logx.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *PreviewOrderLogic) PreviewOrder(req *types.OrderPreviewReq) (resp *types.OrderPreview, err error) {
	userID, err := GetUserIDFromCtx(l.ctx)
	if err != nil {
		return nil, errorx.ErrUnauthorized
	}

	// 获取用户信息（会员等级）
	var user model.User
	if err := l.svcCtx.DB.First(&user, userID).Error; err != nil {
		return nil, errorx.ErrUserNotFound
	}
	levelConfig := model.MemberLevelConfigs[user.MemberLevel]
	if levelConfig.Level == "" {
		levelConfig = model.MemberLevelConfigs[model.MemberLevelNormal]
	}

	// 获取购物车项
	var cartItems []model.CartItem
	if err := l.svcCtx.DB.Where("id IN ? AND user_id = ?", req.CartItemIDs, userID).Find(&cartItems).Error; err != nil {
		return nil, err
	}
	if len(cartItems) == 0 {
		return nil, errorx.NewCodeError(400, "请选择商品")
	}

	// 计算订单金额
	var totalAmount float64
	respItems := make([]types.CartItem, 0, len(cartItems))

	for _, cartItem := range cartItems {
		var product model.Product
		if err := l.svcCtx.DB.First(&product, cartItem.ProductID).Error; err != nil {
			continue
		}

		price := product.Price
		stock := product.Stock
		skuName := ""
		image := product.MainImage

		if cartItem.SkuID > 0 {
			var sku model.ProductSku
			if err := l.svcCtx.DB.First(&sku, cartItem.SkuID).Error; err == nil {
				price = sku.Price
				stock = sku.Stock
				skuName = sku.Name
				if sku.Image != "" {
					image = sku.Image
				}
			}
		}

		itemTotal := price * float64(cartItem.Quantity)
		totalAmount += itemTotal

		respItems = append(respItems, types.CartItem{
			ID:          uint(cartItem.ID),
			ProductID:   cartItem.ProductID,
			SkuID:       cartItem.SkuID,
			ProductName: product.Name,
			SkuName:     skuName,
			Image:       image,
			Price:       price,
			Quantity:    cartItem.Quantity,
			Selected:    true,
			Stock:       stock,
		})
	}

	// 计算会员折扣
	discountAmount := totalAmount * (1 - levelConfig.Discount)

	// 计算运费
	shippingFee := float64(0)
	afterDiscount := totalAmount - discountAmount
	if afterDiscount < levelConfig.FreeShippingMin {
		shippingFee = 10 // 默认运费
	}

	// 计算最大可用积分（最多抵扣20%）
	maxPointsDiscount := afterDiscount * 0.2
	maxPointsUse := int(maxPointsDiscount * 100)
	if maxPointsUse > user.Points {
		maxPointsUse = user.Points
	}
	pointsDiscount := float64(maxPointsUse) / 100

	// 最终支付金额
	payAmount := afterDiscount + shippingFee

	resp = &types.OrderPreview{
		Items:          respItems,
		TotalAmount:    totalAmount,
		DiscountAmount: discountAmount,
		ShippingFee:    shippingFee,
		PayAmount:      payAmount,
		MaxPointsUse:   maxPointsUse,
		PointsDiscount: pointsDiscount,
	}

	return resp, nil
}