var ErrInvalidArgument = errors.New("invalid argument")

type Cargo struct {
	ArrivalDeadline time.Time   `json:"arrival_deadline"`
	Destination     string      `json:"destination"`
	Legs            []cargo.Leg `json:"legs,omitempty"`
	Misrouted       bool        `json:"misrouted"`
	Origin          string      `json:"origin"`
	Routed          bool        `json:"routed"`
	TrackingID      string      `json:"tracking_id"`
}

type Location struct {
	UNLocode string `json:"locode"`
	Name     string `json:"name"`
}

type Service interface {
	// BookNewCargo registers a new cargo in the tracking system, not yet
	// routed.
	BookNewCargo(origin location.UNLocode, destination location.UNLocode, deadline time.Time) (cargo.TrackingID, error)

	// LoadCargo returns a read model of a cargo.
	LoadCargo(id cargo.TrackingID) (Cargo, error)

	// RequestPossibleRoutesForCargo requests a list of itineraries describing
	// possible routes for this cargo.
	RequestPossibleRoutesForCargo(id cargo.TrackingID) []cargo.Itinerary

	// AssignCargoToRoute assigns a cargo to the route specified by the
	// itinerary.
	AssignCargoToRoute(id cargo.TrackingID, itinerary cargo.Itinerary) error

	// ChangeDestination changes the destination of a cargo.
	ChangeDestination(id cargo.TrackingID, destination location.UNLocode) error

	// Cargos returns a list of all cargos that have been booked.
	Cargos() []Cargo

	// Locations returns a list of registered locations.
	Locations() []Location
}