package reactive

type NotificationKind int

const (
	NextNotification NotificationKind = iota
	ErrorNotification
)

type Notification[T any] interface {
	Value() T
	Error() error

	Kind() NotificationKind
}

func MakeNext[T any](v T) Notification[T] {
	return val[T]{v}
}
func MakeError[T any](e error) Notification[T] {
	return err[T]{e}
}

type val[T any] struct {
	value T
}
type err[T any] struct {
	err error
}

func (v val[T]) Value() T {
	return v.value
}
func (v val[T]) Error() error {
	return nil
}
func (v val[T]) Kind() NotificationKind {
	return NextNotification
}

func (e err[T]) Value() T {
	panic("tried to .Value() on an Error notification")
}
func (e err[T]) Error() error {
	return e.err
}
func (e err[T]) Kind() NotificationKind {
	return ErrorNotification
}