cake_crm/internal/services/cart/cart.go

package cart

import (
	"context"
	"errors"
	"strconv"

	"cake_crm/internal/modules/storage"
	"cake_crm/proto"
)

type ProductAndCount struct {
	product *proto.Product
	count   int64
}

type Service struct {
	storage storage.IStorage
}

func NewService(storage storage.IStorage) *Service {
	return &Service{
		storage: storage,
	}
}

func (s *Service) GetCart(ctx context.Context, items []*proto.OrderItem) (*proto.CartRsp, error) {
	var cartAmount int64
	var cartAmountOld int64
	res := make([]*proto.CartItem, 0, len(items))
	for _, item := range items {
		product, err := s.storage.GetProduct(ctx, item.ProductId)
		if err != nil {
			return nil, err
		}
		amount, amountOld, err := calcItemAmount(
			&ProductAndCount{
				product: product,
				count:   item.Count,
			},
		)
		if err != nil {
			return nil, err
		}
		res = append(
			res,
			&proto.CartItem{
				Id:        product.Id,
				Article:   product.Article,
				Name:      product.Name,
				Uri:       product.Uri,
				Images:    product.Images,
				Unit:      product.Unit,
				Inventory: product.Inventory,
				Count:     item.Count,
				Amount:    amount,
				AmountOld: amountOld,
				Discount:  amountOld - amount,
				Variants:  product.Variants,
				Labels:    product.Labels,
			},
		)
		cartAmount += amount
		cartAmountOld += amountOld
	}
	return &proto.CartRsp{
		Items:     res,
		Amount:    cartAmount,
		AmountOld: cartAmountOld,
		Discount:  cartAmountOld - cartAmount,
	}, nil
}

func calcItemAmount(item *ProductAndCount) (int64, int64, error) {
	variantOld := item.product.Variants[0]
	var variant *proto.Variant
	for _, v := range item.product.Variants {
		check := true
		for _, property := range v.Properties {
			if property.Name == "min" {
				minBorder, err := strconv.ParseInt(property.Value, 10, 64)
				if err != nil {
					return 0, 0, err
				}
				if item.count < minBorder {
					check = false
				}
			}
			if property.Name == "max" {
				maxBorder, err := strconv.ParseInt(property.Value, 10, 64)
				if err != nil {
					return 0, 0, err
				}
				if item.count > maxBorder {
					check = false
				}
			}
			if check {
				variant = v
				break
			}
		}
	}
	variant.Active = true
	if variant == nil {
		return 0, 0, errors.New("variant not found")
	}
	return variant.Price * item.count, variantOld.Price * item.count, nil
}