[hw-1] implement cart service

cart/internal/domain/model/cart.go

@@ -0,0 +1,9 @@
+package model
+
+import "route256/cart/internal/domain/entity"
+
+type Cart struct {
+	UserID     entity.UID
+	Items      []*Item
+	TotalPrice uint32
+}

cart/internal/domain/model/errors.go

@@ -0,0 +1,10 @@
+package model
+
+import "errors"
+
+var (
+	ErrProductNotFound = errors.New("invalid sku")
+
+	ErrCartNotFound       = errors.New("cart not found")
+	ErrItemNotFoundInCart = errors.New("item not found in cart")
+)

cart/internal/domain/model/items.go

@@ -0,0 +1,16 @@
+package model
+
+import "fmt"
+
+type Item struct {
+	Product *Product
+	Count   uint32 `validate:"gt=0"`
+}
+
+func (i *Item) Validate() error {
+	if err := validate.Struct(i); err != nil {
+		return fmt.Errorf("invalid requested values: %w", err)
+	}
+
+	return nil
+}

cart/internal/domain/model/product.go

@@ -0,0 +1,21 @@
+package model
+
+import (
+	"fmt"
+
+	"route256/cart/internal/domain/entity"
+)
+
+type Product struct {
+	Name  string
+	Price int32
+	Sku   entity.Sku `validate:"gt=0"`
+}
+
+func (p *Product) Validate() error {
+	if err := validate.Struct(p); err != nil {
+		return fmt.Errorf("invalid requested values: %w", err)
+	}
+
+	return nil
+}

cart/internal/domain/model/validate.go

@@ -0,0 +1,9 @@
+package model
+
+import "github.com/go-playground/validator/v10"
+
+var validate *validator.Validate
+
+func init() {
+	validate = validator.New()
+}