add get card method

internal/services/card/card.go

@@ -0,0 +1,93 @@
+package card
+
+import (
+	"cake_crm/internal/modules/storage"
+	"cake_crm/proto"
+	"context"
+	"errors"
+	"strconv"
+)
+
+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) GetCard(ctx context.Context, items []*proto.OrderItem) ([]*proto.CardItem, error) {
+	res := make([]*proto.CardItem, 0, len(items))
+	for _, item := range items {
+		product, err := s.storage.GetProduct(ctx, item.ProductId)
+		if err != nil {
+			return nil, err
+		}
+		amount, err := calcItemAmount(
+			&ProductAndCount{
+				product: product,
+				count:   item.Count,
+			},
+		)
+		if err != nil {
+			return nil, err
+		}
+		res = append(
+			res,
+			&proto.CardItem{
+				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,
+			},
+		)
+	}
+	return res, nil
+}
+
+func calcItemAmount(item *ProductAndCount) (int64, error) {
+	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, err
+				}
+				if item.count < minBorder {
+					check = false
+				}
+			}
+			if property.Name == "max" {
+				maxBorder, err := strconv.ParseInt(property.Value, 10, 64)
+				if err != nil {
+					return 0, err
+				}
+				if item.count > maxBorder {
+					check = false
+				}
+			}
+			if check {
+				variant = v
+				break
+			}
+		}
+	}
+	if variant == nil {
+		return 0, errors.New("variant not found")
+	}
+	return variant.Price * item.count, nil
+}