// NewMachiner returns a Worker that will wait for the identified machine
// to become Dying and make it Dead; or until the machine becomes Dead by
// other means.
//
// The machineDead function will be called immediately after the machine's
// lifecycle is updated to Dead.
func NewMachiner(cfg Config) (worker.Worker, error) {
	if err := cfg.Validate(); err != nil {
		return nil, errors.Annotate(err, "validating config")
	}
	mr := &Machiner{config: cfg}
	return worker.NewNotifyWorker(mr), nil
}

// NewWorker returns a worker that keeps track of
// the machine's authorised ssh keys and ensures the
// ~/.ssh/authorized_keys file is up to date.
func NewWorker(st *keyupdater.State, agentConfig agent.Config) worker.Worker {
	if os.HostOS() == os.Windows {
		return worker.NewNoOpWorker()
	}
	kw := &keyupdaterWorker{st: st, tag: agentConfig.Tag().(names.MachineTag)}
	return worker.NewNotifyWorker(kw)
}

// NewConnectedStatusWorker creates a new worker that monitors the meter status of the
// unit and runs the meter-status-changed hook appropriately.
func NewConnectedStatusWorker(cfg ConnectedConfig) (worker.Worker, error) {
	handler, err := NewConnectedStatusHandler(cfg)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return worker.NewNotifyWorker(handler), nil
}

// NewWorker returns a worker that keeps track of
// the machine's authorised ssh keys and ensures the
// ~/.ssh/authorized_keys file is up to date.
func NewWorker(st *keyupdater.State, agentConfig agent.Config) worker.Worker {
	if version.Current.OS == version.Windows {
		return worker.NewNoOpWorker()
	}
	kw := &keyupdaterWorker{st: st, tag: agentConfig.Tag().(names.MachineTag)}
	return worker.NewNotifyWorker(kw)
}

// NewRsyslogConfigWorker returns a worker.Worker that uses
// WatchForRsyslogChanges and updates rsyslog configuration based
// on changes. The worker will remove the configuration file
// on teardown.
func NewRsyslogConfigWorker(st *apirsyslog.State, mode RsyslogMode, tag names.Tag, namespace string, stateServerAddrs []string) (worker.Worker, error) {
	handler, err := newRsyslogConfigHandler(st, mode, tag, namespace, stateServerAddrs)
	if err != nil {
		return nil, err
	}
	logger.Debugf("starting rsyslog worker mode %v for %q %q", mode, tag, namespace)
	return worker.NewNotifyWorker(handler), nil
}

// NewLogger returns a worker.Worker that uses the notify watcher returned
// from the setup.
func NewLogger(api *logger.State, agentConfig agent.Config) worker.Worker {
	logger := &Logger{
		api:         api,
		agentConfig: agentConfig,
		lastConfig:  loggo.LoggerInfo(),
	}
	log.Debugf("initial log config: %q", logger.lastConfig)
	return worker.NewNotifyWorker(logger)
}

// NewRsyslogConfigWorker returns a worker.Worker that uses
// WatchForRsyslogChanges and updates rsyslog configuration based
// on changes. The worker will remove the configuration file
// on teardown.
func NewRsyslogConfigWorker(st *apirsyslog.State, mode RsyslogMode, tag names.Tag, namespace string, stateServerAddrs []string) (worker.Worker, error) {
	if version.Current.OS == version.Windows && mode == RsyslogModeAccumulate {
		return worker.NewNoOpWorker(), nil
	}
	handler, err := newRsyslogConfigHandler(st, mode, tag, namespace, stateServerAddrs)
	if err != nil {
		return nil, err
	}
	logger.Debugf("starting rsyslog worker mode %v for %q %q", mode, tag, namespace)
	return worker.NewNotifyWorker(handler), nil
}

// NewCertificateUpdater returns a worker.Worker that watches for changes to
// machine addresses and then generates a new state server certificate with those
// addresses in the certificate's SAN value.
func NewCertificateUpdater(addressWatcher AddressWatcher, getter StateServingInfoGetter,
	configGetter EnvironConfigGetter, setter StateServingInfoSetter, certChanged chan params.StateServingInfo,
) worker.Worker {
	return worker.NewNotifyWorker(&CertificateUpdater{
		addressWatcher: addressWatcher,
		configGetter:   configGetter,
		getter:         getter,
		setter:         setter,
		certChanged:    certChanged,
	})
}

func (s *notifyWorkerSuite) SetUpTest(c *gc.C) {
	s.BaseSuite.SetUpTest(c)
	s.actor = &notifyHandler{
		actions: nil,
		handled: make(chan struct{}, 1),
		watcher: &testNotifyWatcher{
			changes: make(chan struct{}),
		},
	}
	s.worker = worker.NewNotifyWorker(s.actor)
}

// NewCertificateUpdater returns a worker.Worker that watches for changes to
// machine addresses and then generates a new state server certificate with those
// addresses in the certificate's SAN value.
func NewCertificateUpdater(addressWatcher AddressWatcher, getter StateServingInfoGetter,
	configGetter EnvironConfigGetter, hostPortsGetter APIHostPortsGetter, setter StateServingInfoSetter,
) worker.Worker {
	return worker.NewNotifyWorker(&CertificateUpdater{
		addressWatcher:  addressWatcher,
		configGetter:    configGetter,
		hostPortsGetter: hostPortsGetter,
		getter:          getter,
		setter:          setter,
	})
}

func NewReboot(st *reboot.State, agentConfig agent.Config, machineLock *fslock.Lock) (worker.Worker, error) {
	tag, ok := agentConfig.Tag().(names.MachineTag)
	if !ok {
		return nil, errors.Errorf("Expected names.MachineTag, got %T: %v", agentConfig.Tag(), agentConfig.Tag())
	}
	r := &Reboot{
		st:          st,
		tag:         tag,
		machineLock: machineLock,
	}
	return worker.NewNotifyWorker(r), nil
}

// NewNetworker returns a Worker that handles machine networking
// configuration. If there is no /etc/network/interfaces file, an
// error is returned.
func NewNetworker(st *apinetworker.State, agentConfig agent.Config) (worker.Worker, error) {
	nw := &networker{
		st:  st,
		tag: agentConfig.Tag().String(),
	}
	// Verify we have /etc/network/interfaces first, otherwise bail out.
	if !CanStart() {
		err := fmt.Errorf("missing %q config file", configFileName)
		logger.Infof("not starting worker: %v", err)
		return nil, err
	}
	return worker.NewNotifyWorker(nw), nil
}

// NewMachineEnvironmentWorker returns a worker.Worker that uses the notify
// watcher returned from the setup.
func NewMachineEnvironmentWorker(api *environment.Facade, agentConfig agent.Config) worker.Worker {
	// We don't write out system files for the local provider on machine zero
	// as that is the host machine.
	writeSystemFiles := (agentConfig.Tag() != names.NewMachineTag("0").String() ||
		agentConfig.Value(agent.ProviderType) != provider.Local)
	logger.Debugf("write system files: %v", writeSystemFiles)
	envWorker := &MachineEnvironmentWorker{
		api:              api,
		writeSystemFiles: writeSystemFiles,
		first:            true,
	}
	return worker.NewNotifyWorker(envWorker)
}

func (s *notifyWorkerSuite) TestHandleErrorStopsWorkerAndWatcher(c *gc.C) {
	s.stopWorker(c)
	actor := &notifyHandler{
		actions:      nil,
		handled:      make(chan struct{}, 1),
		handlerError: fmt.Errorf("my handling error"),
		watcher: &testNotifyWatcher{
			changes: make(chan struct{}),
		},
	}
	w := worker.NewNotifyWorker(actor)
	actor.watcher.TriggerChange(c)
	waitForHandledNotify(c, actor.handled)
	err := waitShort(c, w)
	c.Check(err, gc.ErrorMatches, "my handling error")
	actor.CheckActions(c, "setup", "handler", "teardown")
	c.Check(actor.watcher.stopped, jc.IsTrue)
}

func (s *notifyWorkerSuite) TestSetUpFailureStopsWithTearDown(c *gc.C) {
	// Stop the worker and SetUp again, this time with an error
	s.stopWorker(c)
	actor := &notifyHandler{
		actions:    nil,
		handled:    make(chan struct{}, 1),
		setupError: fmt.Errorf("my special error"),
		watcher: &testNotifyWatcher{
			changes: make(chan struct{}),
		},
	}
	w := worker.NewNotifyWorker(actor)
	err := waitShort(c, w)
	c.Check(err, gc.ErrorMatches, "my special error")
	// TearDown is not called on SetUp error.
	actor.CheckActions(c, "setup")
	c.Check(actor.watcher.stopped, jc.IsTrue)
}

func newNotifyHandlerWorker(c *gc.C, setupError, handlerError, teardownError error) (*notifyHandler, worker.Worker) {
	nh := &notifyHandler{
		actions:       nil,
		handled:       make(chan struct{}, 1),
		setupError:    setupError,
		teardownError: teardownError,
		handlerError:  handlerError,
		watcher: &testNotifyWatcher{
			changes: make(chan struct{}),
		},
		setupDone: make(chan struct{}),
	}
	w := worker.NewNotifyWorker(nh)
	select {
	case <-nh.setupDone:
	case <-time.After(coretesting.ShortWait):
		c.Error("Failed waiting for notifyHandler.Setup to be called during SetUpTest")
	}
	return nh, w
}

// NewAPIAddressUpdater returns a worker.Worker that runs state.Cleanup()
// if the CleanupWatcher signals documents marked for deletion.
func NewAPIAddressUpdater(addresser APIAddresser, setter APIAddressSetter) worker.Worker {
	return worker.NewNotifyWorker(&APIAddressUpdater{
		addresser: addresser,
		setter:    setter,
	})
}

// NewWorker returns a worker that keeps track of
// the machine's authorised ssh keys and ensures the
// ~/.ssh/authorized_keys file is up to date.
func NewWorker(st *keyupdater.State, agentConfig agent.Config) worker.Worker {
	kw := &keyupdaterWorker{st: st, tag: agentConfig.Tag()}
	return worker.NewNotifyWorker(kw)
}

	// disk.
	first bool
}

var _ worker.NotifyWatchHandler = (*proxyWorker)(nil)

// New returns a worker.Worker that updates proxy environment variables for the
// process; and, if writeSystemFiles is true, for the whole machine.
var New = func(api *environment.Facade, writeSystemFiles bool) worker.Worker {
	logger.Debugf("write system files: %v", writeSystemFiles)
	envWorker := &proxyWorker{
		api:              api,
		writeSystemFiles: writeSystemFiles,
		first:            true,
	}
	return worker.NewNotifyWorker(envWorker)
}

func (w *proxyWorker) writeEnvironmentFile() error {
	// Writing the environment file is handled by executing the script for two
	// primary reasons:
	//
	// 1: In order to have the local provider specify the environment settings
	// for the machine agent running on the host, this worker needs to run,
	// but it shouldn't be touching any files on the disk.  If however there is
	// an ubuntu user, it will. This shouldn't be a problem.
	//
	// 2: On cloud-instance ubuntu images, the ubuntu user is uid 1000, but in
	// the situation where the ubuntu user has been created as a part of the
	// manual provisioning process, the user will exist, and will not have the
	// same uid/gid as the default cloud image.

// NewMachiner returns a Worker that will wait for the identified machine
// to become Dying and make it Dead; or until the machine becomes Dead by
// other means.
func NewMachiner(st MachineAccessor, agentConfig agent.Config) worker.Worker {
	mr := &Machiner{st: st, tag: agentConfig.Tag().(names.MachineTag)}
	return worker.NewNotifyWorker(mr)
}