// Filesystems returns details of filesystems with the specified tags.
func (s *StorageProvisionerAPI) Filesystems(args params.Entities) (params.FilesystemResults, error) {
	canAccess, err := s.getStorageEntityAuthFunc()
	if err != nil {
		return params.FilesystemResults{}, common.ServerError(common.ErrPerm)
	}
	results := params.FilesystemResults{
		Results: make([]params.FilesystemResult, len(args.Entities)),
	}
	one := func(arg params.Entity) (params.Filesystem, error) {
		tag, err := names.ParseFilesystemTag(arg.Tag)
		if err != nil || !canAccess(tag) {
			return params.Filesystem{}, common.ErrPerm
		}
		filesystem, err := s.st.Filesystem(tag)
		if errors.IsNotFound(err) {
			return params.Filesystem{}, common.ErrPerm
		} else if err != nil {
			return params.Filesystem{}, err
		}
		return storagecommon.FilesystemFromState(filesystem)
	}
	for i, arg := range args.Entities {
		var result params.FilesystemResult
		filesystem, err := one(arg)
		if err != nil {
			result.Error = common.ServerError(err)
		} else {
			result.Result = filesystem
		}
		results.Results[i] = result
	}
	return results, nil
}

func createFilesystemInfo(result params.FilesystemDetailsResult) (names.FilesystemTag, FilesystemInfo, error) {
	details := result.Result

	filesystemTag, err := names.ParseFilesystemTag(details.FilesystemTag)
	if err != nil {
		return names.FilesystemTag{}, FilesystemInfo{}, errors.Trace(err)
	}

	var info FilesystemInfo
	info.ProviderFilesystemId = details.Info.FilesystemId
	info.Size = details.Info.Size
	info.Status = EntityStatus{
		details.Status.Status,
		details.Status.Info,
		// TODO(axw) we should support formatting as ISO time
		common.FormatTime(details.Status.Since, false),
	}

	if details.VolumeTag != "" {
		volumeId, err := idFromTag(details.VolumeTag)
		if err != nil {
			return names.FilesystemTag{}, FilesystemInfo{}, errors.Trace(err)
		}
		info.Volume = volumeId
	}

	if len(details.MachineAttachments) > 0 {
		machineAttachments := make(map[string]MachineFilesystemAttachment)
		for machineTag, attachment := range details.MachineAttachments {
			machineId, err := idFromTag(machineTag)
			if err != nil {
				return names.FilesystemTag{}, FilesystemInfo{}, errors.Trace(err)
			}
			machineAttachments[machineId] = MachineFilesystemAttachment{
				attachment.MountPoint,
				attachment.ReadOnly,
			}
		}
		info.Attachments = &FilesystemAttachments{
			Machines: machineAttachments,
		}
	}

	if details.Storage != nil {
		storageTag, storageInfo, err := createStorageInfo(*details.Storage)
		if err != nil {
			return names.FilesystemTag{}, FilesystemInfo{}, errors.Trace(err)
		}
		info.Storage = storageTag.Id()
		if storageInfo.Attachments != nil {
			info.Attachments.Units = storageInfo.Attachments.Units
		}
	}

	return filesystemTag, info, nil
}

// FilesystemToState converts a params.Filesystem to state.FilesystemInfo
// and names.FilesystemTag.
func FilesystemToState(v params.Filesystem) (names.FilesystemTag, state.FilesystemInfo, error) {
	filesystemTag, err := names.ParseFilesystemTag(v.FilesystemTag)
	if err != nil {
		return names.FilesystemTag{}, state.FilesystemInfo{}, errors.Trace(err)
	}
	return filesystemTag, state.FilesystemInfo{
		v.Info.Size,
		"", // pool is set by state
		v.Info.FilesystemId,
	}, nil
}

// FilesystemParams returns the parameters for creating the filesystems
// with the specified tags.
func (s *StorageProvisionerAPI) FilesystemParams(args params.Entities) (params.FilesystemParamsResults, error) {
	canAccess, err := s.getStorageEntityAuthFunc()
	if err != nil {
		return params.FilesystemParamsResults{}, err
	}
	envConfig, err := s.st.EnvironConfig()
	if err != nil {
		return params.FilesystemParamsResults{}, err
	}
	results := params.FilesystemParamsResults{
		Results: make([]params.FilesystemParamsResult, len(args.Entities)),
	}
	poolManager := poolmanager.New(s.settings)
	one := func(arg params.Entity) (params.FilesystemParams, error) {
		tag, err := names.ParseFilesystemTag(arg.Tag)
		if err != nil || !canAccess(tag) {
			return params.FilesystemParams{}, common.ErrPerm
		}
		filesystem, err := s.st.Filesystem(tag)
		if errors.IsNotFound(err) {
			return params.FilesystemParams{}, common.ErrPerm
		} else if err != nil {
			return params.FilesystemParams{}, err
		}
		storageInstance, err := storagecommon.MaybeAssignedStorageInstance(
			filesystem.Storage,
			s.st.StorageInstance,
		)
		if err != nil {
			return params.FilesystemParams{}, err
		}
		filesystemParams, err := storagecommon.FilesystemParams(
			filesystem, storageInstance, envConfig, poolManager,
		)
		if err != nil {
			return params.FilesystemParams{}, err
		}
		return filesystemParams, nil
	}
	for i, arg := range args.Entities {
		var result params.FilesystemParamsResult
		filesystemParams, err := one(arg)
		if err != nil {
			result.Error = common.ServerError(err)
		} else {
			result.Result = filesystemParams
		}
		results.Results[i] = result
	}
	return results, nil
}

// FilesystemAttachmentToState converts a storage.FilesystemAttachment
// to a state.FilesystemAttachmentInfo.
func FilesystemAttachmentToState(in params.FilesystemAttachment) (names.MachineTag, names.FilesystemTag, state.FilesystemAttachmentInfo, error) {
	machineTag, err := names.ParseMachineTag(in.MachineTag)
	if err != nil {
		return names.MachineTag{}, names.FilesystemTag{}, state.FilesystemAttachmentInfo{}, err
	}
	filesystemTag, err := names.ParseFilesystemTag(in.FilesystemTag)
	if err != nil {
		return names.MachineTag{}, names.FilesystemTag{}, state.FilesystemAttachmentInfo{}, err
	}
	info := state.FilesystemAttachmentInfo{
		in.Info.MountPoint,
		in.Info.ReadOnly,
	}
	return machineTag, filesystemTag, info, nil
}

func filesystemAttachmentFromParams(in params.FilesystemAttachment) (storage.FilesystemAttachment, error) {
	filesystemTag, err := names.ParseFilesystemTag(in.FilesystemTag)
	if err != nil {
		return storage.FilesystemAttachment{}, errors.Trace(err)
	}
	machineTag, err := names.ParseMachineTag(in.MachineTag)
	if err != nil {
		return storage.FilesystemAttachment{}, errors.Trace(err)
	}
	return storage.FilesystemAttachment{
		filesystemTag,
		machineTag,
		storage.FilesystemAttachmentInfo{
			in.Info.MountPoint,
			in.Info.ReadOnly,
		},
	}, nil
}

func filesystemAttachmentParamsFromParams(in params.FilesystemAttachmentParams) (storage.FilesystemAttachmentParams, error) {
	machineTag, err := names.ParseMachineTag(in.MachineTag)
	if err != nil {
		return storage.FilesystemAttachmentParams{}, errors.Trace(err)
	}
	filesystemTag, err := names.ParseFilesystemTag(in.FilesystemTag)
	if err != nil {
		return storage.FilesystemAttachmentParams{}, errors.Trace(err)
	}
	return storage.FilesystemAttachmentParams{
		AttachmentParams: storage.AttachmentParams{
			Provider:   storage.ProviderType(in.Provider),
			Machine:    machineTag,
			InstanceId: instance.Id(in.InstanceId),
			ReadOnly:   in.ReadOnly,
		},
		Filesystem:   filesystemTag,
		FilesystemId: in.FilesystemId,
		Path:         in.MountPoint,
	}, nil
}

func filesystemFromParams(in params.Filesystem) (storage.Filesystem, error) {
	filesystemTag, err := names.ParseFilesystemTag(in.FilesystemTag)
	if err != nil {
		return storage.Filesystem{}, errors.Trace(err)
	}
	var volumeTag names.VolumeTag
	if in.VolumeTag != "" {
		volumeTag, err = names.ParseVolumeTag(in.VolumeTag)
		if err != nil {
			return storage.Filesystem{}, errors.Trace(err)
		}
	}
	return storage.Filesystem{
		filesystemTag,
		volumeTag,
		storage.FilesystemInfo{
			in.Info.FilesystemId,
			in.Info.Size,
		},
	}, nil
}

func filesystemParamsFromParams(in params.FilesystemParams) (storage.FilesystemParams, error) {
	filesystemTag, err := names.ParseFilesystemTag(in.FilesystemTag)
	if err != nil {
		return storage.FilesystemParams{}, errors.Trace(err)
	}
	var volumeTag names.VolumeTag
	if in.VolumeTag != "" {
		volumeTag, err = names.ParseVolumeTag(in.VolumeTag)
		if err != nil {
			return storage.FilesystemParams{}, errors.Trace(err)
		}
	}
	providerType := storage.ProviderType(in.Provider)
	return storage.FilesystemParams{
		filesystemTag,
		volumeTag,
		in.Size,
		providerType,
		in.Attributes,
		in.Tags,
	}, nil
}

func (s *StorageProvisionerAPI) oneFilesystemAttachment(
	id params.MachineStorageId, canAccess func(names.MachineTag, names.Tag) bool,
) (state.FilesystemAttachment, error) {
	machineTag, err := names.ParseMachineTag(id.MachineTag)
	if err != nil {
		return nil, err
	}
	filesystemTag, err := names.ParseFilesystemTag(id.AttachmentTag)
	if err != nil {
		return nil, err
	}
	if !canAccess(machineTag, filesystemTag) {
		return nil, common.ErrPerm
	}
	filesystemAttachment, err := s.st.FilesystemAttachment(machineTag, filesystemTag)
	if errors.IsNotFound(err) {
		return nil, common.ErrPerm
	} else if err != nil {
		return nil, err
	}
	return filesystemAttachment, nil
}

func assertParseFilesystemTagInvalid(c *gc.C, tag string, expect error) {
	_, err := names.ParseFilesystemTag(tag)
	c.Assert(err, gc.ErrorMatches, expect.Error())
}

func assertParseFilesystemTag(c *gc.C, tag string, expect names.FilesystemTag) {
	t, err := names.ParseFilesystemTag(tag)
	c.Assert(err, gc.IsNil)
	c.Assert(t, gc.Equals, expect)
}