func (m *mockStorageAccessor) StorageAttachmentLife(ids []params.StorageAttachmentId) ([]params.LifeResult, error) {
	if m.storageAttachmentLife != nil {
		return m.storageAttachmentLife(ids)
	}
	results := make([]params.LifeResult, len(ids))
	for i, id := range ids {
		storageTag, err := names.ParseStorageTag(id.StorageTag)
		if err != nil {
			results[i].Error = common.ServerError(err)
			continue
		}
		unitTag, err := names.ParseUnitTag(id.UnitTag)
		if err != nil {
			results[i].Error = common.ServerError(err)
			continue
		}
		att, err := m.storageAttachment(storageTag, unitTag)
		if err != nil {
			results[i].Error = common.ServerError(err)
			continue
		}
		results[i].Life = att.Life
	}
	return results, nil
}

// AddMetricBatches adds the metrics for the specified unit.
func (u *UniterAPIV2) AddMetricBatches(args params.MetricBatchParams) (params.ErrorResults, error) {
	result := params.ErrorResults{
		Results: make([]params.ErrorResult, len(args.Batches)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		logger.Warningf("failed to check unit access: %v", err)
		return params.ErrorResults{}, common.ErrPerm
	}
	for i, batch := range args.Batches {
		tag, err := names.ParseUnitTag(batch.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(err)
			continue
		}
		if !canAccess(tag) {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		metrics := make([]state.Metric, len(batch.Batch.Metrics))
		for j, metric := range batch.Batch.Metrics {
			metrics[j] = state.Metric{
				Key:   metric.Key,
				Value: metric.Value,
				Time:  metric.Time,
			}
		}
		_, err = u.unit.AddMetrics(batch.Batch.UUID, batch.Batch.Created, batch.Batch.CharmURL, metrics)
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

func (s startUniter) step(c *gc.C, ctx *context) {
	if s.unitTag == "" {
		s.unitTag = "unit-u-0"
	}
	if ctx.uniter != nil {
		panic("don't start two uniters!")
	}
	if ctx.api == nil {
		panic("API connection not established")
	}
	tag, err := names.ParseUnitTag(s.unitTag)
	if err != nil {
		panic(err.Error())
	}
	locksDir := filepath.Join(ctx.dataDir, "locks")
	lock, err := fslock.NewLock(locksDir, "uniter-hook-execution")
	c.Assert(err, jc.ErrorIsNil)
	uniterParams := uniter.UniterParams{
		St:                ctx.api,
		UnitTag:           tag,
		LeadershipManager: ctx.leader,
		DataDir:           ctx.dataDir,
		HookLock:          lock,
		MetricsTimerChooser: uniter.NewTestingMetricsTimerChooser(
			ctx.collectMetricsTicker.ReturnTimer,
			ctx.sendMetricsTicker.ReturnTimer,
		),
		UpdateStatusSignal:   ctx.updateStatusHookTicker.ReturnTimer,
		NewOperationExecutor: s.newExecutorFunc,
	}
	ctx.uniter = uniter.NewUniter(&uniterParams)
	uniter.SetUniterObserver(ctx.uniter, ctx)
}

func (c *RunCommand) Init(args []string) error {
	// make sure we aren't in an existing hook context
	if contextId, err := getenv("JUJU_CONTEXT_ID"); err == nil && contextId != "" {
		return fmt.Errorf("juju-run cannot be called from within a hook, have context %q", contextId)
	}
	if !c.noContext {
		if len(args) < 1 {
			return fmt.Errorf("missing unit-name")
		}
		var unitName string
		unitName, args = args[0], args[1:]
		// If the command line param is a unit id (like service/2) we need to
		// change it to the unit tag as that is the format of the agent directory
		// on disk (unit-service-2).
		if names.IsValidUnit(unitName) {
			c.unit = names.NewUnitTag(unitName)
		} else {
			var err error
			c.unit, err = names.ParseUnitTag(unitName)
			if err != nil {
				return errors.Trace(err)
			}
		}
	}
	if len(args) < 1 {
		return fmt.Errorf("missing commands")
	}
	c.commands, args = args[0], args[1:]
	return cmd.CheckEmpty(args)
}

// AssignedMachine returns the machine tag for each given unit tag, or
// an error satisfying params.IsCodeNotAssigned when a unit has no
// assigned machine.
func (u *UniterAPIV1) AssignedMachine(args params.Entities) (params.StringResults, error) {
	result := params.StringResults{
		Results: make([]params.StringResult, len(args.Entities)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.StringResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseUnitTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		if !canAccess(tag) {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		unit, err := u.getUnit(tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(err)
			continue
		}
		machineId, err := unit.AssignedMachineId()
		if err != nil {
			result.Results[i].Error = common.ServerError(err)
		} else {
			result.Results[i].Result = names.NewMachineTag(machineId).String()
		}
	}
	return result, nil
}

// UpdateSettings persists all changes made to the local settings of
// all given pairs of relation and unit. Keys with empty values are
// considered a signal to delete these values.
func (u *UniterAPI) UpdateSettings(args params.RelationUnitsSettings) (params.ErrorResults, error) {
	result := params.ErrorResults{
		Results: make([]params.ErrorResult, len(args.RelationUnits)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.ErrorResults{}, err
	}
	for i, arg := range args.RelationUnits {
		unit, err := names.ParseUnitTag(arg.Unit)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		relUnit, err := u.getRelationUnit(canAccess, arg.Relation, unit)
		if err == nil {
			var settings *state.Settings
			settings, err = relUnit.Settings()
			if err == nil {
				for k, v := range arg.Settings {
					if v == "" {
						settings.Delete(k)
					} else {
						settings.Set(k, v)
					}
				}
				_, err = settings.Write()
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// ReadSettings returns the local settings of each given set of
// relation/unit.
func (u *UniterAPI) ReadSettings(args params.RelationUnits) (params.RelationSettingsResults, error) {
	result := params.RelationSettingsResults{
		Results: make([]params.RelationSettingsResult, len(args.RelationUnits)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.RelationSettingsResults{}, err
	}
	for i, arg := range args.RelationUnits {
		unit, err := names.ParseUnitTag(arg.Unit)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		relUnit, err := u.getRelationUnit(canAccess, arg.Relation, unit)
		if err == nil {
			var settings *state.Settings
			settings, err = relUnit.Settings()
			if err == nil {
				result.Results[i].Settings, err = convertRelationSettings(settings.Map())
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// ReadRemoteSettings returns the remote settings of each given set of
// relation/local unit/remote unit.
func (u *UniterAPI) ReadRemoteSettings(args params.RelationUnitPairs) (params.RelationSettingsResults, error) {
	result := params.RelationSettingsResults{
		Results: make([]params.RelationSettingsResult, len(args.RelationUnitPairs)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.RelationSettingsResults{}, err
	}
	for i, arg := range args.RelationUnitPairs {
		unit, err := names.ParseUnitTag(arg.LocalUnit)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		relUnit, err := u.getRelationUnit(canAccess, arg.Relation, unit)
		if err == nil {
			// TODO(dfc) rework this logic
			remoteUnit := ""
			remoteUnit, err = u.checkRemoteUnit(relUnit, arg.RemoteUnit)
			if err == nil {
				var settings map[string]interface{}
				settings, err = relUnit.ReadSettings(remoteUnit)
				if err == nil {
					result.Results[i].Settings, err = convertRelationSettings(settings)
				}
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// JoinedRelations returns the tags of all relations for which each supplied unit
// has entered scope. It should be called RelationsInScope, but it's not convenient
// to make that change until we have versioned APIs.
func (u *UniterAPI) JoinedRelations(args params.Entities) (params.StringsResults, error) {
	result := params.StringsResults{
		Results: make([]params.StringsResult, len(args.Entities)),
	}
	if len(args.Entities) == 0 {
		return result, nil
	}
	canRead, err := u.accessUnit()
	if err != nil {
		return params.StringsResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseUnitTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		err = common.ErrPerm
		if canRead(tag) {
			var unit *state.Unit
			unit, err = u.getUnit(tag)
			if err == nil {
				result.Results[i].Result, err = relationsInScopeTags(unit)
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// GetMeterStatus returns meter status information for each unit.
func (u *uniterBaseAPI) GetMeterStatus(args params.Entities) (params.MeterStatusResults, error) {
	result := params.MeterStatusResults{
		Results: make([]params.MeterStatusResult, len(args.Entities)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.MeterStatusResults{}, common.ErrPerm
	}
	for i, entity := range args.Entities {
		unitTag, err := names.ParseUnitTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		err = common.ErrPerm
		var status state.MeterStatus
		if canAccess(unitTag) {
			var unit *state.Unit
			unit, err = u.getUnit(unitTag)
			if err == nil {
				status, err = meterstatus.MeterStatusWrapper(unit.GetMeterStatus)
			}
			result.Results[i].Code = status.Code.String()
			result.Results[i].Info = status.Info
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// SetCharmURL sets the charm URL for each given unit. An error will
// be returned if a unit is dead, or the charm URL is not know.
func (u *UniterAPI) SetCharmURL(args params.EntitiesCharmURL) (params.ErrorResults, error) {
	result := params.ErrorResults{
		Results: make([]params.ErrorResult, len(args.Entities)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.ErrorResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseUnitTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		err = common.ErrPerm
		if canAccess(tag) {
			var unit *state.Unit
			unit, err = u.getUnit(tag)
			if err == nil {
				var curl *charm.URL
				curl, err = charm.ParseURL(entity.CharmURL)
				if err == nil {
					err = unit.SetCharmURL(curl)
				}
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// ConfigSettings returns the complete set of service charm config
// settings available to each given unit.
func (u *UniterAPI) ConfigSettings(args params.Entities) (params.ConfigSettingsResults, error) {
	result := params.ConfigSettingsResults{
		Results: make([]params.ConfigSettingsResult, len(args.Entities)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.ConfigSettingsResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseUnitTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		err = common.ErrPerm
		if canAccess(tag) {
			var unit *state.Unit
			unit, err = u.getUnit(tag)
			if err == nil {
				var settings charm.Settings
				settings, err = unit.ConfigSettings()
				if err == nil {
					result.Results[i].Settings = params.ConfigSettings(settings)
				}
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// DestroyAllSubordinates destroys all subordinates of each given unit.
func (u *uniterBaseAPI) DestroyAllSubordinates(args params.Entities) (params.ErrorResults, error) {
	result := params.ErrorResults{
		Results: make([]params.ErrorResult, len(args.Entities)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.ErrorResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseUnitTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		err = common.ErrPerm
		if canAccess(tag) {
			var unit *state.Unit
			unit, err = u.getUnit(tag)
			if err == nil {
				err = u.destroySubordinates(unit)
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

func (s *StorageAPI) watchOneStorageAttachment(id params.StorageAttachmentId, canAccess func(names.Tag) bool) (params.NotifyWatchResult, error) {
	// Watching a storage attachment is implemented as watching the
	// underlying volume or filesystem attachment. The only thing
	// we don't necessarily see in doing this is the lifecycle state
	// changes, but these may be observed by using the
	// WatchUnitStorageAttachments watcher.
	nothing := params.NotifyWatchResult{}
	unitTag, err := names.ParseUnitTag(id.UnitTag)
	if err != nil || !canAccess(unitTag) {
		return nothing, common.ErrPerm
	}
	storageTag, err := names.ParseStorageTag(id.StorageTag)
	if err != nil {
		return nothing, err
	}
	machineTag, err := s.st.UnitAssignedMachine(unitTag)
	if err != nil {
		return nothing, err
	}
	watch, err := common.WatchStorageAttachment(s.st, storageTag, machineTag, unitTag)
	if err != nil {
		return nothing, errors.Trace(err)
	}
	if _, ok := <-watch.Changes(); ok {
		return params.NotifyWatchResult{
			NotifyWatcherId: s.resources.Register(watch),
		}, nil
	}
	return nothing, watcher.EnsureErr(watch)
}

func (s startUniter) step(c *gc.C, ctx *context) {
	if s.unitTag == "" {
		s.unitTag = "unit-u-0"
	}
	if ctx.uniter != nil {
		panic("don't start two uniters!")
	}
	if ctx.api == nil {
		panic("API connection not established")
	}
	tag, err := names.ParseUnitTag(s.unitTag)
	if err != nil {
		panic(err.Error())
	}
	locksDir := filepath.Join(ctx.dataDir, "locks")
	lock, err := fslock.NewLock(locksDir, "uniter-hook-execution")
	c.Assert(err, jc.ErrorIsNil)
	operationExecutor := operation.NewExecutor
	if s.newExecutorFunc != nil {
		operationExecutor = s.newExecutorFunc
	}

	uniterParams := uniter.UniterParams{
		UniterFacade:         ctx.api,
		UnitTag:              tag,
		LeadershipTracker:    ctx.leaderTracker,
		CharmDirLocker:       ctx.charmDirLocker,
		DataDir:              ctx.dataDir,
		MachineLock:          lock,
		UpdateStatusSignal:   ctx.updateStatusHookTicker.ReturnTimer,
		NewOperationExecutor: operationExecutor,
		Observer:             ctx,
	}
	ctx.uniter = uniter.NewUniter(&uniterParams)
}

// PrivateAddress returns the private address for each given unit, if set.
func (u *uniterBaseAPI) PrivateAddress(args params.Entities) (params.StringResults, error) {
	result := params.StringResults{
		Results: make([]params.StringResult, len(args.Entities)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.StringResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseUnitTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		err = common.ErrPerm
		if canAccess(tag) {
			var unit *state.Unit
			unit, err = u.getUnit(tag)
			if err == nil {
				var address network.Address
				address, err = unit.PrivateAddress()
				if err == nil {
					result.Results[i].Result = address.Value
				} else if network.IsNoAddress(err) {
					err = common.NoAddressSetError(tag, "private")
				}
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// AddMetricBatches implements the MetricsAdder interface.
func (api *MetricsAdderAPI) AddMetricBatches(args params.MetricBatchParams) (params.ErrorResults, error) {
	result := params.ErrorResults{
		Results: make([]params.ErrorResult, len(args.Batches)),
	}
	for i, batch := range args.Batches {
		tag, err := names.ParseUnitTag(batch.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(err)
			continue
		}
		metrics := make([]state.Metric, len(batch.Batch.Metrics))
		for j, metric := range batch.Batch.Metrics {
			metrics[j] = state.Metric{
				Key:   metric.Key,
				Value: metric.Value,
				Time:  metric.Time,
			}
		}
		_, err = api.state.AddMetrics(
			state.BatchParam{
				UUID:     batch.Batch.UUID,
				Created:  batch.Batch.Created,
				CharmURL: batch.Batch.CharmURL,
				Metrics:  metrics,
				Unit:     tag,
			},
		)
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// API2Payload converts an API Payload info struct into
// a payload.FullPayloadInfo struct.
func API2Payload(apiInfo Payload) (payload.FullPayloadInfo, error) {
	labels := make([]string, len(apiInfo.Labels))
	copy(labels, apiInfo.Labels)

	var unit, machine string
	var empty payload.FullPayloadInfo
	if apiInfo.Unit != "" {
		tag, err := names.ParseUnitTag(apiInfo.Unit)
		if err != nil {
			return empty, errors.Trace(err)
		}
		unit = tag.Id()
	}
	if apiInfo.Machine != "" {
		tag, err := names.ParseMachineTag(apiInfo.Machine)
		if err != nil {
			return empty, errors.Trace(err)
		}
		machine = tag.Id()
	}

	return payload.FullPayloadInfo{
		Payload: payload.Payload{
			PayloadClass: charm.PayloadClass{
				Name: apiInfo.Class,
				Type: apiInfo.Type,
			},
			ID:     apiInfo.ID,
			Status: apiInfo.Status,
			Labels: labels,
			Unit:   unit,
		},
		Machine: machine,
	}, nil
}

// OpenedPorts returns a map of network.PortRange to unit tag for all opened
// port ranges on the machine for the subnet matching given subnetTag.
func (m *Machine) OpenedPorts(subnetTag names.SubnetTag) (map[network.PortRange]names.UnitTag, error) {
	var results params.MachinePortsResults
	var subnetTagAsString string
	if subnetTag.Id() != "" {
		subnetTagAsString = subnetTag.String()
	}
	args := params.MachinePortsParams{
		Params: []params.MachinePorts{
			{MachineTag: m.tag.String(), SubnetTag: subnetTagAsString},
		},
	}
	err := m.st.facade.FacadeCall("GetMachinePorts", args, &results)
	if err != nil {
		return nil, err
	}
	if len(results.Results) != 1 {
		return nil, fmt.Errorf("expected 1 result, got %d", len(results.Results))
	}
	result := results.Results[0]
	if result.Error != nil {
		return nil, result.Error
	}
	// Convert string tags to names.UnitTag before returning.
	endResult := make(map[network.PortRange]names.UnitTag)
	for _, ports := range result.Ports {
		unitTag, err := names.ParseUnitTag(ports.UnitTag)
		if err != nil {
			return nil, err
		}
		endResult[ports.PortRange.NetworkPortRange()] = unitTag
	}
	return endResult, nil
}

// GetPrincipal returns the result of calling PrincipalName() and
// converting it to a tag, on each given unit.
func (u *UniterAPI) GetPrincipal(args params.Entities) (params.StringBoolResults, error) {
	result := params.StringBoolResults{
		Results: make([]params.StringBoolResult, len(args.Entities)),
	}
	canAccess, err := u.accessUnit()
	if err != nil {
		return params.StringBoolResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseUnitTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		err = common.ErrPerm
		if canAccess(tag) {
			var unit *state.Unit
			unit, err = u.getUnit(tag)
			if err == nil {
				principal, ok := unit.PrincipalName()
				if principal != "" {
					result.Results[i].Result = names.NewUnitTag(principal).String()
				}
				result.Results[i].Ok = ok
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}