package constants

// SellBy describes how a product's quantity is expressed on an order line.
type SellBy = string

const (
	// SellByUnit is the default: the line counts discrete items (2 portions, 3 bottles).
	SellByUnit SellBy = "unit"
	// SellByWeight means the line carries a weighed amount. One weighing is one line,
	// so quantity stays 1 and the measured value lives in order_items.weight.
	SellByWeight SellBy = "weight"
)

// IsValidSellBy reports whether s is a supported sell_by value.
func IsValidSellBy(s string) bool {
	return s == SellByUnit || s == SellByWeight
}