// ServiceOwner returns the owner user for each given service tag.
func (u *UniterAPIV1) ServiceOwner(args params.Entities) (params.StringResults, error) {
	result := params.StringResults{
		Results: make([]params.StringResult, len(args.Entities)),
	}
	canAccess, err := u.accessService()
	if err != nil {
		return params.StringResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseServiceTag(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
		}
		service, err := u.getService(tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(err)
			continue
		}
		result.Results[i].Result = service.GetOwnerTag()
	}
	return result, nil
}

func (u *UniterAPI) getService(tag string) (*state.Service, error) {
	t, err := names.ParseServiceTag(tag)
	if err != nil {
		return nil, err
	}
	return u.st.Service(t.Id())
}

// Merge merges in the provided leadership settings. Only leaders for
// the given service may perform this operation.
func (lsa *LeadershipSettingsAccessor) Merge(bulkArgs params.MergeLeadershipSettingsBulkParams) (params.ErrorResults, error) {

	callerUnitId := lsa.authorizer.GetAuthTag().Id()
	requireServiceId, err := names.UnitService(callerUnitId)
	if err != nil {
		return params.ErrorResults{}, err
	}
	results := make([]params.ErrorResult, len(bulkArgs.Params))

	for i, arg := range bulkArgs.Params {
		result := &results[i]

		// TODO(fwereade): we shoudn't assume a ServiceTag: we should
		// use an actual auth func to determine permissions.
		serviceTag, err := names.ParseServiceTag(arg.ServiceTag)
		if err != nil {
			result.Error = common.ServerError(err)
			continue
		}

		serviceId := serviceTag.Id()
		if serviceId != requireServiceId {
			result.Error = common.ServerError(common.ErrPerm)
			continue
		}

		token := lsa.leaderCheckFn(serviceId, callerUnitId)
		err = lsa.mergeSettingsChunkFn(token, serviceId, arg.Settings)
		if err != nil {
			result.Error = common.ServerError(err)
		}
	}

	return params.ErrorResults{Results: results}, nil
}

// parseServiceTag attempts to parse the given serviceTag, and if it
// fails returns an error which is safe to return to the client -- in
// both a structure and security context.
func parseServiceTag(serviceTag string) (names.ServiceTag, *params.Error) {
	parsedTag, err := names.ParseServiceTag(serviceTag)
	if err != nil {
		// We intentionally mask the real error for security purposes.
		return names.ServiceTag{}, common.ServerError(common.ErrPerm)
	}
	return parsedTag, nil
}

func parseServiceTag(tagStr string) (names.ServiceTag, *params.Error) { // note the concrete error type
	serviceTag, err := names.ParseServiceTag(tagStr)
	if err != nil {
		return serviceTag, &params.Error{
			Message: err.Error(),
			Code:    params.CodeBadRequest,
		}
	}
	return serviceTag, nil
}

func (s *serviceSuite) TestParseServiceTag(c *gc.C) {
	for i, t := range parseServiceTagTests {
		c.Logf("test %d: %s", i, t.tag)
		got, err := names.ParseServiceTag(t.tag)
		if err != nil || t.err != nil {
			c.Check(err, gc.DeepEquals, t.err)
			continue
		}
		c.Check(got, gc.FitsTypeOf, t.expected)
		c.Check(got, gc.Equals, t.expected)
	}
}

// TODO(dimitern) bug #1270795 2014-01-20
// Add a doc comment here and use u.accessService()
// below in the body to check for permissions.
func (u *UniterAPI) GetOwnerTag(args params.Entities) (params.StringResult, error) {
	var nothing params.StringResult
	tag, err := names.ParseServiceTag(args.Entities[0].Tag)
	if err != nil {
		return nothing, common.ErrPerm
	}
	service, err := u.getService(tag)
	if err != nil {
		return nothing, err
	}
	return params.StringResult{
		Result: service.GetOwnerTag(),
	}, nil
}

// parseServiceAndUnitTags takes in string representations of service
// and unit tags and returns their corresponding tags.
func parseServiceAndUnitTags(
	serviceTagString, unitTagString string,
) (
	names.ServiceTag, names.UnitTag, error,
) {
	// TODO(fwereade) 2015-02-25 bug #1425506
	// These permissions errors are not appropriate -- there's no permission or
	// security issue in play here, because our tag format is public, and the
	// error only triggers when the strings fail to match that format.
	serviceTag, err := names.ParseServiceTag(serviceTagString)
	if err != nil {
		return names.ServiceTag{}, names.UnitTag{}, common.ErrPerm
	}

	unitTag, err := names.ParseUnitTag(unitTagString)
	if err != nil {
		return names.ServiceTag{}, names.UnitTag{}, common.ErrPerm
	}

	return serviceTag, unitTag, nil
}

// WatchServiceRelations returns a StringsWatcher, for each given
// service, that notifies of changes to the lifecycles of relations
// involving that service.
func (u *UniterAPI) WatchServiceRelations(args params.Entities) (params.StringsWatchResults, error) {
	result := params.StringsWatchResults{
		Results: make([]params.StringsWatchResult, len(args.Entities)),
	}
	canAccess, err := u.accessService()
	if err != nil {
		return params.StringsWatchResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseServiceTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		err = common.ErrPerm
		if canAccess(tag) {
			result.Results[i], err = u.watchOneServiceRelations(tag)
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// Read reads leadership settings for the provided service ID. Any
// unit of the service may perform this operation.
func (lsa *LeadershipSettingsAccessor) Read(bulkArgs params.Entities) (params.GetLeadershipSettingsBulkResults, error) {

	callerUnitId := lsa.authorizer.GetAuthTag().Id()
	requireServiceId, err := names.UnitService(callerUnitId)
	if err != nil {
		return params.GetLeadershipSettingsBulkResults{}, err
	}
	results := make([]params.GetLeadershipSettingsResult, len(bulkArgs.Entities))

	for i, arg := range bulkArgs.Entities {
		result := &results[i]

		// TODO(fwereade): we shoudn't assume a ServiceTag: we should
		// use an actual auth func to determine permissions.
		serviceTag, err := names.ParseServiceTag(arg.Tag)
		if err != nil {
			result.Error = common.ServerError(err)
			continue
		}

		serviceId := serviceTag.Id()
		if serviceId != requireServiceId {
			result.Error = common.ServerError(common.ErrPerm)
			continue
		}

		settings, err := lsa.getSettingsFn(serviceId)
		if err != nil {
			result.Error = common.ServerError(err)
			continue
		}

		result.Settings = settings
	}

	return params.GetLeadershipSettingsBulkResults{results}, nil
}

// ServicesCharmActions returns a slice of charm Actions for a slice of
// services.
func (a *ActionAPI) ServicesCharmActions(args params.Entities) (params.ServicesCharmActionsResults, error) {
	result := params.ServicesCharmActionsResults{Results: make([]params.ServiceCharmActionsResult, len(args.Entities))}
	for i, entity := range args.Entities {
		currentResult := &result.Results[i]
		svcTag, err := names.ParseServiceTag(entity.Tag)
		if err != nil {
			currentResult.Error = common.ServerError(common.ErrBadId)
			continue
		}
		currentResult.ServiceTag = svcTag.String()
		svc, err := a.state.Service(svcTag.Id())
		if err != nil {
			currentResult.Error = common.ServerError(err)
			continue
		}
		ch, _, err := svc.Charm()
		if err != nil {
			currentResult.Error = common.ServerError(err)
			continue
		}
		currentResult.Actions = ch.Actions()
	}
	return result, nil
}

func (u *Uniter) init(unitTag string) (err error) {
	tag, err := names.ParseUnitTag(unitTag)
	if err != nil {
		return err
	}
	u.unit, err = u.st.Unit(tag)
	if err != nil {
		return err
	}
	if u.unit.Life() == params.Dead {
		// If we started up already dead, we should not progress further. If we
		// become Dead immediately after starting up, we may well complete any
		// operations in progress before detecting it; but that race is fundamental
		// and inescapable, whereas this one is not.
		return worker.ErrTerminateAgent
	}
	if err = u.setupLocks(); err != nil {
		return err
	}
	u.toolsDir = tools.ToolsDir(u.dataDir, unitTag)
	if err := EnsureJujucSymlinks(u.toolsDir); err != nil {
		return err
	}
	u.baseDir = filepath.Join(u.dataDir, "agents", unitTag)
	u.relationsDir = filepath.Join(u.baseDir, "state", "relations")
	if err := os.MkdirAll(u.relationsDir, 0755); err != nil {
		return err
	}
	serviceTag, err := names.ParseServiceTag(u.unit.ServiceTag())
	if err != nil {
		return err
	}
	u.service, err = u.st.Service(serviceTag)
	if err != nil {
		return err
	}
	var env *uniter.Environment
	env, err = u.st.Environment()
	if err != nil {
		return err
	}
	u.uuid = env.UUID()
	u.envName = env.Name()

	u.relationers = map[int]*Relationer{}
	u.relationHooks = make(chan hook.Info)
	u.charmPath = filepath.Join(u.baseDir, "charm")
	deployerPath := filepath.Join(u.baseDir, "state", "deployer")
	bundles := charm.NewBundlesDir(filepath.Join(u.baseDir, "state", "bundles"))
	u.deployer, err = charm.NewDeployer(u.charmPath, deployerPath, bundles)
	if err != nil {
		return fmt.Errorf("cannot create deployer: %v", err)
	}
	u.sf = NewStateFile(filepath.Join(u.baseDir, "state", "uniter"))
	u.rand = rand.New(rand.NewSource(time.Now().Unix()))

	// If we start trying to listen for juju-run commands before we have valid
	// relation state, surprising things will come to pass.
	if err := u.restoreRelations(); err != nil {
		return err
	}
	runListenerSocketPath := filepath.Join(u.baseDir, RunListenerFile)
	logger.Debugf("starting juju-run listener on unix:%s", runListenerSocketPath)
	u.runListener, err = NewRunListener(u, runListenerSocketPath)
	if err != nil {
		return err
	}
	// The socket needs to have permissions 777 in order for other users to use it.
	return os.Chmod(runListenerSocketPath, 0777)
}