// CharmURL returns the charm URL for all given units or services.
func (u *UniterAPIV3) CharmURL(args params.Entities) (params.StringBoolResults, error) {
	result := params.StringBoolResults{
		Results: make([]params.StringBoolResult, len(args.Entities)),
	}
	accessUnitOrService := common.AuthEither(u.accessUnit, u.accessService)
	canAccess, err := accessUnitOrService()
	if err != nil {
		return params.StringBoolResults{}, err
	}
	for i, entity := range args.Entities {
		tag, err := names.ParseTag(entity.Tag)
		if err != nil {
			result.Results[i].Error = common.ServerError(common.ErrPerm)
			continue
		}
		err = common.ErrPerm
		if canAccess(tag) {
			var unitOrService state.Entity
			unitOrService, err = u.st.FindEntity(tag)
			if err == nil {
				charmURLer := unitOrService.(interface {
					CharmURL() (*charm.URL, bool)
				})
				curl, ok := charmURLer.CharmURL()
				if curl != nil {
					result.Results[i].Result = curl.String()
					result.Results[i].Ok = ok
				}
			}
		}
		result.Results[i].Error = common.ServerError(err)
	}
	return result, nil
}

// stateForRequestAuthenticatedAgent is like stateForRequestAuthenticated
// except that it also verifies that the authenticated entity is an agent.
func (ctxt *httpContext) stateForRequestAuthenticatedAgent(r *http.Request) (*state.State, state.Entity, error) {
	authFunc := common.AuthEither(
		common.AuthFuncForTagKind(names.MachineTagKind),
		common.AuthFuncForTagKind(names.UnitTagKind),
	)
	st, entity, err := ctxt.stateForRequestAuthenticated(r)
	if err != nil {
		return nil, nil, errors.Trace(err)
	}
	if ok, err := checkPermissions(entity.Tag(), authFunc); !ok {
		return nil, nil, err
	}
	return st, entity, nil
}

func (s *commonSuite) TestAuthEither(c *gc.C) {
	for i, test := range authEitherTests {
		c.Logf("test %d: %s", i, test.about)
		authEither := common.AuthEither(test.a, test.b)
		either, err := authEither()
		if test.err == "" {
			c.Assert(err, jc.ErrorIsNil)
			ok := either(test.tag)
			c.Assert(ok, gc.Equals, test.expect)
		} else {
			c.Assert(err, gc.ErrorMatches, test.err)
			c.Assert(either, gc.IsNil)
		}
	}
}

// CharmModifiedVersion returns the most CharmModifiedVersion for all given
// units or services.
func (u *UniterAPIV3) CharmModifiedVersion(args params.Entities) (params.IntResults, error) {
	results := params.IntResults{
		Results: make([]params.IntResult, len(args.Entities)),
	}

	accessUnitOrService := common.AuthEither(u.accessUnit, u.accessService)
	canAccess, err := accessUnitOrService()
	if err != nil {
		return results, err
	}
	for i, entity := range args.Entities {
		ver, err := u.charmModifiedVersion(entity.Tag, canAccess)
		if err != nil {
			results.Results[i].Error = common.ServerError(err)
			continue
		}
		results.Results[i].Result = ver
	}
	return results, nil
}

// NewUniterAPI creates a new instance of the Uniter API.
func NewUniterAPI(st *state.State, resources *common.Resources, authorizer common.Authorizer) (*UniterAPI, error) {
	if !authorizer.AuthUnitAgent() {
		return nil, common.ErrPerm
	}
	accessUnit := func() (common.AuthFunc, error) {
		return authorizer.AuthOwner, nil
	}
	accessService := func() (common.AuthFunc, error) {
		switch tag := authorizer.GetAuthTag().(type) {
		case names.UnitTag:
			entity, err := st.Unit(tag.Id())
			if err != nil {
				return nil, errors.Trace(err)
			}
			serviceName := entity.ServiceName()
			serviceTag := names.NewServiceTag(serviceName)
			return func(tag names.Tag) bool {
				return tag == serviceTag
			}, nil
		default:
			return nil, errors.Errorf("expected names.UnitTag, got %T", tag)
		}
	}
	accessUnitOrService := common.AuthEither(accessUnit, accessService)

	return &UniterAPI{
		LifeGetter:         common.NewLifeGetter(st, accessUnitOrService),
		StatusSetter:       common.NewStatusSetter(st, accessUnit),
		DeadEnsurer:        common.NewDeadEnsurer(st, accessUnit),
		AgentEntityWatcher: common.NewAgentEntityWatcher(st, resources, accessUnitOrService),
		APIAddresser:       common.NewAPIAddresser(st, resources),
		EnvironWatcher:     common.NewEnvironWatcher(st, resources, authorizer),

		st:            st,
		auth:          authorizer,
		resources:     resources,
		accessUnit:    accessUnit,
		accessService: accessService,
	}, nil
}

// NewUniterAPIV4 creates a new instance of the Uniter API, version 3.
func NewUniterAPIV4(st *state.State, resources facade.Resources, authorizer facade.Authorizer) (*UniterAPIV3, error) {
	if !authorizer.AuthUnitAgent() {
		return nil, common.ErrPerm
	}
	var unit *state.Unit
	var err error
	switch tag := authorizer.GetAuthTag().(type) {
	case names.UnitTag:
		unit, err = st.Unit(tag.Id())
		if err != nil {
			return nil, errors.Trace(err)
		}
	default:
		return nil, errors.Errorf("expected names.UnitTag, got %T", tag)
	}
	accessUnit := func() (common.AuthFunc, error) {
		return authorizer.AuthOwner, nil
	}
	accessService := func() (common.AuthFunc, error) {
		switch tag := authorizer.GetAuthTag().(type) {
		case names.UnitTag:
			entity, err := st.Unit(tag.Id())
			if err != nil {
				return nil, errors.Trace(err)
			}
			applicationName := entity.ApplicationName()
			applicationTag := names.NewApplicationTag(applicationName)
			return func(tag names.Tag) bool {
				return tag == applicationTag
			}, nil
		default:
			return nil, errors.Errorf("expected names.UnitTag, got %T", tag)
		}
	}
	accessMachine := func() (common.AuthFunc, error) {
		switch tag := authorizer.GetAuthTag().(type) {
		case names.UnitTag:
			entity, err := st.Unit(tag.Id())
			if err != nil {
				return nil, errors.Trace(err)
			}
			machineId, err := entity.AssignedMachineId()
			if err != nil {
				return nil, errors.Trace(err)
			}
			machineTag := names.NewMachineTag(machineId)
			return func(tag names.Tag) bool {
				return tag == machineTag
			}, nil
		default:
			return nil, errors.Errorf("expected names.UnitTag, got %T", tag)
		}
	}
	storageAPI, err := newStorageAPI(getStorageState(st), resources, accessUnit)
	if err != nil {
		return nil, err
	}
	msAPI, err := meterstatus.NewMeterStatusAPI(st, resources, authorizer)
	if err != nil {
		return nil, errors.Annotate(err, "could not create meter status API handler")
	}
	accessUnitOrService := common.AuthEither(accessUnit, accessService)
	return &UniterAPIV3{
		LifeGetter:                 common.NewLifeGetter(st, accessUnitOrService),
		DeadEnsurer:                common.NewDeadEnsurer(st, accessUnit),
		AgentEntityWatcher:         common.NewAgentEntityWatcher(st, resources, accessUnitOrService),
		APIAddresser:               common.NewAPIAddresser(st, resources),
		ModelWatcher:               common.NewModelWatcher(st, resources, authorizer),
		RebootRequester:            common.NewRebootRequester(st, accessMachine),
		LeadershipSettingsAccessor: leadershipSettingsAccessorFactory(st, resources, authorizer),
		MeterStatus:                msAPI,
		// TODO(fwereade): so *every* unit should be allowed to get/set its
		// own status *and* its service's? This is not a pleasing arrangement.
		StatusAPI: NewStatusAPI(st, accessUnitOrService),

		st:            st,
		auth:          authorizer,
		resources:     resources,
		accessUnit:    accessUnit,
		accessService: accessService,
		accessMachine: accessMachine,
		unit:          unit,
		StorageAPI:    *storageAPI,
	}, nil
}

// NewFirewallerAPI creates a new server-side FirewallerAPI facade.
func NewFirewallerAPI(
	st *state.State,
	resources facade.Resources,
	authorizer facade.Authorizer,
) (*FirewallerAPI, error) {
	if !authorizer.AuthModelManager() {
		// Firewaller must run as environment manager.
		return nil, common.ErrPerm
	}
	// Set up the various authorization checkers.
	accessEnviron := common.AuthFuncForTagKind(names.ModelTagKind)
	accessUnit := common.AuthFuncForTagKind(names.UnitTagKind)
	accessService := common.AuthFuncForTagKind(names.ApplicationTagKind)
	accessMachine := common.AuthFuncForTagKind(names.MachineTagKind)
	accessUnitOrService := common.AuthEither(accessUnit, accessService)
	accessUnitServiceOrMachine := common.AuthEither(accessUnitOrService, accessMachine)

	// Life() is supported for units, services or machines.
	lifeGetter := common.NewLifeGetter(
		st,
		accessUnitServiceOrMachine,
	)
	// ModelConfig() and WatchForModelConfigChanges() are allowed
	// with unrestriced access.
	modelWatcher := common.NewModelWatcher(
		st,
		resources,
		authorizer,
	)
	// Watch() is supported for applications only.
	entityWatcher := common.NewAgentEntityWatcher(
		st,
		resources,
		accessService,
	)
	// WatchUnits() is supported for machines.
	unitsWatcher := common.NewUnitsWatcher(st,
		resources,
		accessMachine,
	)
	// WatchModelMachines() is allowed with unrestricted access.
	machinesWatcher := common.NewModelMachinesWatcher(
		st,
		resources,
		authorizer,
	)
	// InstanceId() is supported for machines.
	instanceIdGetter := common.NewInstanceIdGetter(
		st,
		accessMachine,
	)

	environConfigGetter := stateenvirons.EnvironConfigGetter{st}
	cloudSpecAPI := cloudspec.NewCloudSpec(environConfigGetter.CloudSpec, common.AuthFuncForTag(st.ModelTag()))

	return &FirewallerAPI{
		LifeGetter:           lifeGetter,
		ModelWatcher:         modelWatcher,
		AgentEntityWatcher:   entityWatcher,
		UnitsWatcher:         unitsWatcher,
		ModelMachinesWatcher: machinesWatcher,
		InstanceIdGetter:     instanceIdGetter,
		CloudSpecAPI:         cloudSpecAPI,
		st:                   st,
		resources:            resources,
		authorizer:           authorizer,
		accessUnit:           accessUnit,
		accessService:        accessService,
		accessMachine:        accessMachine,
		accessEnviron:        accessEnviron,
	}, nil
}

// newUniterBaseAPI creates a new instance of the uniter base API.
func newUniterBaseAPI(st *state.State, resources *common.Resources, authorizer common.Authorizer) (*uniterBaseAPI, error) {
	if !authorizer.AuthUnitAgent() {
		return nil, common.ErrPerm
	}
	var unit *state.Unit
	var err error
	switch tag := authorizer.GetAuthTag().(type) {
	case names.UnitTag:
		unit, err = st.Unit(tag.Id())
		if err != nil {
			return nil, errors.Trace(err)
		}
	default:
		return nil, errors.Errorf("expected names.UnitTag, got %T", tag)
	}
	accessUnit := func() (common.AuthFunc, error) {
		return authorizer.AuthOwner, nil
	}
	accessService := func() (common.AuthFunc, error) {
		switch tag := authorizer.GetAuthTag().(type) {
		case names.UnitTag:
			entity, err := st.Unit(tag.Id())
			if err != nil {
				return nil, errors.Trace(err)
			}
			serviceName := entity.ServiceName()
			serviceTag := names.NewServiceTag(serviceName)
			return func(tag names.Tag) bool {
				return tag == serviceTag
			}, nil
		default:
			return nil, errors.Errorf("expected names.UnitTag, got %T", tag)
		}
	}
	accessMachine := func() (common.AuthFunc, error) {
		machineId, err := unit.AssignedMachineId()
		if err != nil {
			return nil, errors.Trace(err)
		}
		machine, err := st.Machine(machineId)
		if err != nil {
			return nil, errors.Trace(err)
		}
		return func(tag names.Tag) bool {
			return tag == machine.Tag()
		}, nil
	}

	accessUnitOrService := common.AuthEither(accessUnit, accessService)
	return &uniterBaseAPI{
		LifeGetter:                 common.NewLifeGetter(st, accessUnitOrService),
		DeadEnsurer:                common.NewDeadEnsurer(st, accessUnit),
		AgentEntityWatcher:         common.NewAgentEntityWatcher(st, resources, accessUnitOrService),
		APIAddresser:               common.NewAPIAddresser(st, resources),
		EnvironWatcher:             common.NewEnvironWatcher(st, resources, authorizer),
		RebootRequester:            common.NewRebootRequester(st, accessMachine),
		LeadershipSettingsAccessor: leadershipSettingsAccessorFactory(st, resources, authorizer),

		// TODO(fwereade): so *every* unit should be allowed to get/set its
		// own status *and* its service's? This is not a pleasing arrangement.
		StatusAPI: NewStatusAPI(st, accessUnitOrService),

		st:            st,
		auth:          authorizer,
		resources:     resources,
		accessUnit:    accessUnit,
		accessService: accessService,
		unit:          unit,
	}, nil
}

// NewFirewallerAPI creates a new server-side FirewallerAPI facade.
func NewFirewallerAPI(
	st *state.State,
	resources *common.Resources,
	authorizer common.Authorizer,
) (*FirewallerAPI, error) {
	if !authorizer.AuthEnvironManager() {
		// Firewaller must run as environment manager.
		return nil, common.ErrPerm
	}
	// Set up the various authorization checkers.
	accessEnviron := common.AuthFuncForTagKind(names.EnvironTagKind)
	accessUnit := common.AuthFuncForTagKind(names.UnitTagKind)
	accessService := common.AuthFuncForTagKind(names.ServiceTagKind)
	accessMachine := common.AuthFuncForTagKind(names.MachineTagKind)
	accessUnitOrService := common.AuthEither(accessUnit, accessService)
	accessUnitServiceOrMachine := common.AuthEither(accessUnitOrService, accessMachine)

	// Life() is supported for units, services or machines.
	lifeGetter := common.NewLifeGetter(
		st,
		accessUnitServiceOrMachine,
	)
	// EnvironConfig() and WatchForEnvironConfigChanges() are allowed
	// with unrestriced access.
	environWatcher := common.NewEnvironWatcher(
		st,
		resources,
		authorizer,
	)
	// Watch() is supported for services only.
	entityWatcher := common.NewAgentEntityWatcher(
		st,
		resources,
		accessService,
	)
	// WatchUnits() is supported for machines.
	unitsWatcher := common.NewUnitsWatcher(st,
		resources,
		accessMachine,
	)
	// WatchEnvironMachines() is allowed with unrestricted access.
	machinesWatcher := common.NewEnvironMachinesWatcher(
		st,
		resources,
		authorizer,
	)
	// InstanceId() is supported for machines.
	instanceIdGetter := common.NewInstanceIdGetter(
		st,
		accessMachine,
	)

	return &FirewallerAPI{
		LifeGetter:             lifeGetter,
		EnvironWatcher:         environWatcher,
		AgentEntityWatcher:     entityWatcher,
		UnitsWatcher:           unitsWatcher,
		EnvironMachinesWatcher: machinesWatcher,
		InstanceIdGetter:       instanceIdGetter,
		st:                     st,
		resources:              resources,
		authorizer:             authorizer,
		accessUnit:             accessUnit,
		accessService:          accessService,
		accessMachine:          accessMachine,
		accessEnviron:          accessEnviron,
	}, nil
}