func (context *statusContext) processService(service *state.Service) (status api.ServiceStatus) {
	serviceCharmURL, _ := service.CharmURL()
	status.Charm = serviceCharmURL.String()
	status.Exposed = service.IsExposed()
	status.Life = processLife(service)

	latestCharm, ok := context.latestCharms[*serviceCharmURL.WithRevision(-1)]
	if ok && latestCharm != serviceCharmURL.String() {
		status.CanUpgradeTo = latestCharm
	}
	var err error
	status.Relations, status.SubordinateTo, err = context.processRelations(service)
	if err != nil {
		status.Err = err
		return
	}
	includeNetworks, excludeNetworks, err := service.Networks()
	if err == nil {
		status.Networks = api.NetworksSpecification{
			Enabled:  includeNetworks,
			Disabled: excludeNetworks,
		}
	}
	if service.IsPrincipal() {
		status.Units = context.processUnits(context.units[service.Name()], serviceCharmURL.String())
	}
	return status
}

// assertForceMachine ensures that the result of assigning a unit with --to
// is as expected.
func (s *AddUnitSuite) assertForceMachine(c *gc.C, svc *state.Service, expectedNumMachines, unitNum int, machineId string) {
	units, err := svc.AllUnits()
	c.Assert(err, gc.IsNil)
	c.Assert(units, gc.HasLen, expectedNumMachines)
	mid, err := units[unitNum].AssignedMachineId()
	c.Assert(err, gc.IsNil)
	c.Assert(mid, gc.Equals, machineId)
}

// assertSetSuccess sets configuration options and checks the expected settings.
func assertSetSuccess(c *gc.C, dir string, svc *state.Service, args []string, expect charm.Settings) {
	ctx := coretesting.ContextForDir(c, dir)
	code := cmd.Main(&SetCommand{}, ctx, append([]string{"dummy-service"}, args...))
	c.Check(code, gc.Equals, 0)
	settings, err := svc.ConfigSettings()
	c.Assert(err, gc.IsNil)
	c.Assert(settings, gc.DeepEquals, expect)
}

func removeAllUnits(c *gc.C, s *state.Service) {
	us, err := s.AllUnits()
	c.Assert(err, gc.IsNil)
	for _, u := range us {
		err = u.EnsureDead()
		c.Assert(err, gc.IsNil)
		err = u.Remove()
		c.Assert(err, gc.IsNil)
	}
}

// serviceSetSettingsStrings updates the settings for the given service,
// taking the configuration from a map of strings.
func serviceSetSettingsStrings(service *state.Service, settings map[string]string) error {
	ch, _, err := service.Charm()
	if err != nil {
		return err
	}
	// Parse config in a compatible way (see function comment).
	changes, err := parseSettingsCompatible(ch, settings)
	if err != nil {
		return err
	}
	return service.UpdateConfigSettings(changes)
}

func (s *runSuite) addUnit(c *gc.C, service *state.Service) *state.Unit {
	unit, err := service.AddUnit()
	c.Assert(err, gc.IsNil)
	err = unit.AssignToNewMachine()
	c.Assert(err, gc.IsNil)
	mId, err := unit.AssignedMachineId()
	c.Assert(err, gc.IsNil)
	machine, err := s.State.Machine(mId)
	c.Assert(err, gc.IsNil)
	machine.SetAddresses(instance.NewAddress("10.3.2.1", instance.NetworkUnknown))
	return unit
}

func (s *HookContextSuite) AddUnit(c *gc.C, svc *state.Service) *state.Unit {
	unit, err := svc.AddUnit()
	c.Assert(err, gc.IsNil)
	s.machine, err = s.State.AddMachine("quantal", state.JobHostUnits)
	c.Assert(err, gc.IsNil)
	err = unit.AssignToMachine(s.machine)
	c.Assert(err, gc.IsNil)
	name := strings.Replace(unit.Name(), "/", "-", 1)
	privateAddr := instance.NewAddress(name+".testing.invalid", instance.NetworkCloudLocal)
	err = s.machine.SetAddresses(privateAddr)
	c.Assert(err, gc.IsNil)
	return unit
}

// newServiceSetSettingsStringsForClientAPI updates the settings for the given
// service, taking the configuration from a map of strings.
//
// TODO(Nate): replace serviceSetSettingsStrings with this onces the GUI no
// longer expects to be able to unset values by sending an empty string.
func newServiceSetSettingsStringsForClientAPI(service *state.Service, settings map[string]string) error {
	ch, _, err := service.Charm()
	if err != nil {
		return err
	}

	// Validate the settings.
	changes, err := ch.Config().ParseSettingsStrings(settings)
	if err != nil {
		return err
	}

	return service.UpdateConfigSettings(changes)
}

func (s *ServiceSuite) assertServiceRelations(c *gc.C, svc *state.Service, expectedKeys ...string) []*state.Relation {
	rels, err := svc.Relations()
	c.Assert(err, gc.IsNil)
	if len(rels) == 0 {
		return nil
	}
	relKeys := make([]string, len(expectedKeys))
	for i, rel := range rels {
		relKeys[i] = rel.String()
	}
	sort.Strings(relKeys)
	c.Assert(relKeys, gc.DeepEquals, expectedKeys)
	return rels
}

func (*statusContext) processRelations(service *state.Service) (related map[string][]string, subord []string, err error) {
	// TODO(mue) This way the same relation is read twice (for each service).
	// Maybe add Relations() to state, read them only once and pass them to each
	// call of this function.
	relations, err := service.Relations()
	if err != nil {
		return nil, nil, err
	}
	var subordSet set.Strings
	related = make(map[string][]string)
	for _, relation := range relations {
		ep, err := relation.Endpoint(service.Name())
		if err != nil {
			return nil, nil, err
		}
		relationName := ep.Relation.Name
		eps, err := relation.RelatedEndpoints(service.Name())
		if err != nil {
			return nil, nil, err
		}
		for _, ep := range eps {
			if ep.Scope == charm.ScopeContainer && !service.IsPrincipal() {
				subordSet.Add(ep.ServiceName)
			}
			related[relationName] = append(related[relationName], ep.ServiceName)
		}
	}
	for relationName, serviceNames := range related {
		sn := set.NewStrings(serviceNames...)
		related[relationName] = sn.SortedValues()
	}
	return related, subordSet.SortedValues(), nil
}

func (s *DeployLocalSuite) assertMachines(c *gc.C, service *state.Service, expectCons constraints.Value, expectIds ...string) {
	units, err := service.AllUnits()
	c.Assert(err, gc.IsNil)
	c.Assert(units, gc.HasLen, len(expectIds))
	unseenIds := set.NewStrings(expectIds...)
	for _, unit := range units {
		id, err := unit.AssignedMachineId()
		c.Assert(err, gc.IsNil)
		unseenIds.Remove(id)
		machine, err := s.State.Machine(id)
		c.Assert(err, gc.IsNil)
		cons, err := machine.Constraints()
		c.Assert(err, gc.IsNil)
		c.Assert(cons, gc.DeepEquals, expectCons)
	}
	c.Assert(unseenIds, gc.DeepEquals, set.NewStrings())
}

// serviceSetCharm sets the charm for the given service.
func (c *Client) serviceSetCharm(service *state.Service, url string, force bool) error {
	curl, err := charm.ParseURL(url)
	if err != nil {
		return err
	}
	sch, err := c.api.state.Charm(curl)
	if errors.IsNotFound(err) {
		// Charms should be added before trying to use them, with
		// AddCharm or AddLocalCharm API calls. When they're not,
		// we're reverting to 1.16 compatibility mode.
		return c.serviceSetCharm1dot16(service, curl, force)
	}
	if err != nil {
		return err
	}
	return service.SetCharm(sch, force)
}

// serviceSetCharm1dot16 sets the charm for the given service in 1.16
// compatibility mode. Remove this when support for 1.16 is dropped.
func (c *Client) serviceSetCharm1dot16(service *state.Service, curl *charm.URL, force bool) error {
	if curl.Schema != "cs" {
		return fmt.Errorf(`charm url has unsupported schema %q`, curl.Schema)
	}
	if curl.Revision < 0 {
		return fmt.Errorf("charm url must include revision")
	}
	err := c.AddCharm(params.CharmURL{curl.String()})
	if err != nil {
		return err
	}
	ch, err := c.api.state.Charm(curl)
	if err != nil {
		return err
	}
	return service.SetCharm(ch, force)
}

// GetExposed returns the exposed flag value for each given service.
func (f *FirewallerAPI) GetExposed(args params.Entities) (params.BoolResults, error) {
	result := params.BoolResults{
		Results: make([]params.BoolResult, len(args.Entities)),
	}
	canAccess, err := f.accessService()
	if err != nil {
		return params.BoolResults{}, err
	}
	for i, entity := range args.Entities {
		var service *state.Service
		service, err = f.getService(canAccess, entity.Tag)
		if err == nil {
			result.Results[i].Result = service.IsExposed()
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

func assertOneRelation(c *gc.C, srv *state.Service, relId int, endpoints ...state.Endpoint) *state.Relation {
	rels, err := srv.Relations()
	c.Assert(err, gc.IsNil)
	c.Assert(rels, gc.HasLen, 1)
	rel := rels[0]
	c.Assert(rel.Id(), gc.Equals, relId)
	name := srv.Name()
	expectEp := endpoints[0]
	ep, err := rel.Endpoint(name)
	c.Assert(err, gc.IsNil)
	c.Assert(ep, gc.DeepEquals, expectEp)
	if len(endpoints) == 2 {
		expectEp = endpoints[1]
	}
	eps, err := rel.RelatedEndpoints(name)
	c.Assert(err, gc.IsNil)
	c.Assert(eps, gc.DeepEquals, []state.Endpoint{expectEp})
	return rel
}

func NewProReqRelation(c *gc.C, s *ConnSuite, scope charm.RelationScope) *ProReqRelation {
	psvc := s.AddTestingService(c, "mysql", s.AddTestingCharm(c, "mysql"))
	var rsvc *state.Service
	if scope == charm.ScopeGlobal {
		rsvc = s.AddTestingService(c, "wordpress", s.AddTestingCharm(c, "wordpress"))
	} else {
		rsvc = s.AddTestingService(c, "logging", s.AddTestingCharm(c, "logging"))
	}
	eps, err := s.State.InferEndpoints([]string{"mysql", rsvc.Name()})
	c.Assert(err, gc.IsNil)
	rel, err := s.State.AddRelation(eps...)
	c.Assert(err, gc.IsNil)
	prr := &ProReqRelation{rel: rel, psvc: psvc, rsvc: rsvc}
	prr.pu0, prr.pru0 = addRU(c, psvc, rel, nil)
	prr.pu1, prr.pru1 = addRU(c, psvc, rel, nil)
	if scope == charm.ScopeGlobal {
		prr.ru0, prr.rru0 = addRU(c, rsvc, rel, nil)
		prr.ru1, prr.rru1 = addRU(c, rsvc, rel, nil)
	} else {
		prr.ru0, prr.rru0 = addRU(c, rsvc, rel, prr.pu0)
		prr.ru1, prr.rru1 = addRU(c, rsvc, rel, prr.pu1)
	}
	return prr
}

// serviceSetSettingsYAML updates the settings for the given service,
// taking the configuration from a YAML string.
func serviceSetSettingsYAML(service *state.Service, settings string) error {
	ch, _, err := service.Charm()
	if err != nil {
		return err
	}
	changes, err := ch.Config().ParseSettingsYAML([]byte(settings), service.Name())
	if err != nil {
		return err
	}
	return service.UpdateConfigSettings(changes)
}

func removeServiceAndUnits(c *gc.C, service *state.Service) {
	// Destroy all units for the service.
	units, err := service.AllUnits()
	c.Assert(err, gc.IsNil)
	for _, unit := range units {
		err = unit.EnsureDead()
		c.Assert(err, gc.IsNil)
		err = unit.Remove()
		c.Assert(err, gc.IsNil)
	}
	err = service.Destroy()
	c.Assert(err, gc.IsNil)

	err = service.Refresh()
	c.Assert(err, jc.Satisfies, errors.IsNotFound)
}

func addRU(c *gc.C, svc *state.Service, rel *state.Relation, principal *state.Unit) (*state.Unit, *state.RelationUnit) {
	// Given the service svc in the relation rel, add a unit of svc and create
	// a RelationUnit with rel. If principal is supplied, svc is assumed to be
	// subordinate and the unit will be created by temporarily entering the
	// relation's scope as the principal.
	var u *state.Unit
	if principal == nil {
		unit, err := svc.AddUnit()
		c.Assert(err, gc.IsNil)
		u = unit
	} else {
		origUnits, err := svc.AllUnits()
		c.Assert(err, gc.IsNil)
		pru, err := rel.Unit(principal)
		c.Assert(err, gc.IsNil)
		err = pru.EnterScope(nil) // to create the subordinate
		c.Assert(err, gc.IsNil)
		err = pru.LeaveScope() // to reset to initial expected state
		c.Assert(err, gc.IsNil)
		newUnits, err := svc.AllUnits()
		c.Assert(err, gc.IsNil)
		for _, unit := range newUnits {
			found := false
			for _, old := range origUnits {
				if unit.Name() == old.Name() {
					found = true
					break
				}
			}
			if !found {
				u = unit
				break
			}
		}
		c.Assert(u, gc.NotNil)
	}
	preventUnitDestroyRemove(c, u)
	ru, err := rel.Unit(u)
	c.Assert(err, gc.IsNil)
	return u, ru
}

func assertNoRelations(c *gc.C, srv *state.Service) {
	rels, err := srv.Relations()
	c.Assert(err, gc.IsNil)
	c.Assert(rels, gc.HasLen, 0)
}