package daemon

import (
	"sync"

	"src.dualinventive.com/go/devsim"
	"src.dualinventive.com/go/devsim/repository"
	"src.dualinventive.com/go/devsim/simulator"
	"src.dualinventive.com/go/devsim/transport"
	"src.dualinventive.com/go/dinet"
	"src.dualinventive.com/go/lib/dilog"
)

type simulatorService struct {
	simulatorsMx sync.Mutex
	templates    map[string]*TemplateTracker
	simulators   map[string]simulator.Simulator
	repService   repository.Service
	smpEndpoint  string
	storage      Storage
	loggerDir    string
}

// List return the current managed simulators
func (s *simulatorService) List() []simulator.Simulator {
	s.simulatorsMx.Lock()
	defer s.simulatorsMx.Unlock()
	sims := make([]simulator.Simulator, 0, len(s.simulators))
	for _, sim := range s.simulators {
		sims = append(sims, sim)
	}
	return sims
}

// Add adds a new simulator in the list of managed simulators. The simulator is prepared to start, but is
// not started yet.
func (s *simulatorService) Add(uri string, version string) (simulator.Info, error) {
	r, err := s.repService.Find(uri)
	if err != nil {
		return nil, err
	}
	key, err := r.Key(version)
	if err != nil {
		return nil, err
	}
	tracker, err := s.createTemplateIfNotExist(r, key)
	if err != nil {
		return nil, err
	}

	deviceUID, err := s.storage.GetNextDeviceUID()
	if err != nil {
		return nil, err
	}

	// Indicate that we are using this template. This creates the template if nessesary
	tracker.Increment()
	tpl := tracker.Info()
	templateInfo := &template{Info: tpl, deviceUID: deviceUID}

	// Get the driver
	driver := s.getDriver(templateInfo)
	if driver == nil {
		tracker.Decrement()
		return nil, ErrInvalidTemplate
	}

	// Get the model
	model, err := s.getModel(deviceUID)
	if err != nil {
		tracker.Decrement()
		return nil, err
	}

	// Create the simulator
	sim, err := simulator.NewSimulator(driver.Name(), model, templateInfo)
	if err != nil {
		tracker.Decrement()
		return nil, err
	}

	s.simulatorsMx.Lock()
	defer s.simulatorsMx.Unlock()
	if _, ok := s.simulators[deviceUID]; ok {
		tracker.Decrement()
		// This should not happen because we requested a deviceUID
		return nil, devsim.ErrAlreadyExists
	}
	s.simulators[deviceUID] = sim
	return templateInfo, nil
}

// Get returns the simulator with the given deviceUID or an ErrNotFound it returned when the simulator is
// not found.
func (s *simulatorService) Get(deviceUID string) (simulator.Simulator, error) {
	return s.getByDeviceUID(deviceUID)
}

// Remove removes the simulator of the list of managed simulators. This simulator must be stopped in order
// to succeeds. An ErrNotFound is returned when the simulator is not found. An ErrNotStopped is returned when the
// simulator is still running.
func (s *simulatorService) Remove(deviceUID string) error {
	sim, err := s.getByDeviceUID(deviceUID)
	if err != nil {
		return err
	}

	key := sim.Key()
	if tTracker, ok := s.templates[key]; ok {
		tTracker.Decrement()
	}
	// TODO check if simulator is running
	delete(s.simulators, deviceUID)
	return nil
}

func (s *simulatorService) getByDeviceUID(deviceUID string) (simulator.Simulator, error) {
	s.simulatorsMx.Lock()
	defer s.simulatorsMx.Unlock()
	sim, ok := s.simulators[deviceUID]
	if !ok {
		return nil, devsim.ErrNotFound
	}
	return sim, nil
}

// Start starts the simulator with the given deviceUID. An ErrNotFound is returned when the simulator is
// not found. An ErrAlreadyRunning is returned when the simulator is already running.
func (s *simulatorService) Start(deviceUID string) error {
	sim, err := s.getByDeviceUID(deviceUID)
	if err != nil {
		return err
	}
	// TODO check if simulator is running
	return sim.Start()
}

// Stop stops the simulator with the given deviceUID. An ErrNotFound is returned when the simulator is
// not found. An ErrAlreadyStopped is returned when the simulator is already stopped.
func (s *simulatorService) Stop(deviceUID string) error {
	sim, err := s.getByDeviceUID(deviceUID)
	if err != nil {
		return err
	}
	// TODO check if simulator is running
	return sim.Stop()
}

func (s *simulatorService) createTemplateIfNotExist(rep repository.Repository, key string) (*TemplateTracker, error) {
	tTracker, ok := s.templates[key]
	if !ok {
		t, err := rep.Template(key)
		if err != nil {
			return nil, err
		}
		tTracker = &TemplateTracker{
			usage:    0,
			template: t,
		}
		s.templates[key] = tTracker
	}
	return tTracker, nil
}

// getDriver returns the first valid driver that can execute the given template info
func (s *simulatorService) getDriver(t simulator.Info) simulator.Driver {
	// Search for a valid driver that can execute our template
	drivers := simulator.Drivers()
	for _, driver := range drivers {
		if driver.Valid(t) {
			return driver
		}
	}
	return nil
}

// getModel returns the model that can be inserted in the simulator
func (s *simulatorService) getModel(deviceUID string) (simulator.Model, error) {

	dStorage := s.storage.GetDeviceStorage(deviceUID)
	if dStorage == nil {
		return nil, ErrCannotCreateStorage
	}

	dTransport, err := transport.NewDinet(dinet.TransportLowlevel, deviceUID, s.smpEndpoint)
	if err != nil {
		return nil, err
	}

	// TODO get deviceUID logger
	discard := dilog.NewNilLogger()
	return simulator.NewModel(discard, dStorage, dTransport), nil
}