// Package inspection provides means to inspect cargos.
package inspection

import (
	shipping "github.com/longjoy/micro-go-course/section19/cargo/model"
)

// EventHandler provides means of subscribing to inspection events.
type EventHandler interface {
	CargoWasMisdirected(*shipping.Cargo)
	CargoHasArrived(*shipping.Cargo)
}

// Service provides cargo inspection operations.
type Service interface {
	// InspectCargo inspects cargo and send relevant notifications to
	// interested parties, for example if a cargo has been misdirected, or
	// unloaded at the final destination.
	InspectCargo(id shipping.TrackingID)
}

type service struct {
	cargos  shipping.CargoRepository
	events  shipping.HandlingEventRepository
	handler EventHandler
}

// TODO: Should be transactional
func (s *service) InspectCargo(id shipping.TrackingID) {
	c, err := s.cargos.Find(id)
	if err != nil {
		return
	}

	h := s.events.QueryHandlingHistory(id)

	c.DeriveDeliveryProgress(h)

	if c.Delivery.IsMisdirected {
		s.handler.CargoWasMisdirected(c)
	}

	if c.Delivery.IsUnloadedAtDestination {
		s.handler.CargoHasArrived(c)
	}

	s.cargos.Store(c)
}

// NewService creates a inspection service with necessary dependencies.
func NewService(cargos shipping.CargoRepository, events shipping.HandlingEventRepository, handler EventHandler) Service {
	return &service{cargos, events, handler}
}