// TODO(axw) move this and createParamsStorageInstance to
// apiserver/common/storage.go, alongside StorageAttachmentInfo.
func (api *API) isPersistent(si state.StorageInstance) (bool, error) {
	if si.Kind() != state.StorageKindBlock {
		// TODO(axw) when we support persistent filesystems,
		// e.g. CephFS, we'll need to do the same thing as
		// we do for volumes for filesystems.
		return false, nil
	}
	volume, err := api.storage.StorageInstanceVolume(si.StorageTag())
	if err != nil {
		return false, err
	}
	// If the volume is not provisioned, we read its config attributes.
	if params, ok := volume.Params(); ok {
		_, cfg, err := common.StoragePoolConfig(params.Pool, api.poolManager)
		if err != nil {
			return false, err
		}
		return cfg.IsPersistent(), nil
	}
	// If the volume is provisioned, we look at its provisioning info.
	info, err := volume.Info()
	if err != nil {
		return false, err
	}
	return info.Persistent, nil
}

func volumeStorageAttachmentInfo(
	st StorageInterface,
	storageInstance state.StorageInstance,
	machineTag names.MachineTag,
) (*storage.StorageAttachmentInfo, error) {
	storageTag := storageInstance.StorageTag()
	volume, err := st.StorageInstanceVolume(storageTag)
	if err != nil {
		return nil, errors.Annotate(err, "getting volume")
	}
	volumeInfo, err := volume.Info()
	if err != nil {
		return nil, errors.Annotate(err, "getting volume info")
	}
	volumeAttachment, err := st.VolumeAttachment(machineTag, volume.VolumeTag())
	if err != nil {
		return nil, errors.Annotate(err, "getting volume attachment")
	}
	volumeAttachmentInfo, err := volumeAttachment.Info()
	if err != nil {
		return nil, errors.Annotate(err, "getting volume attachment info")
	}
	devicePath, err := volumeAttachmentDevicePath(
		volumeInfo,
		volumeAttachmentInfo,
	)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return &storage.StorageAttachmentInfo{
		storage.StorageKindBlock,
		devicePath,
	}, nil
}

// storageTags returns the tags that should be set on a volume or filesystem,
// if the provider supports them.
func storageTags(
	storageInstance state.StorageInstance,
	cfg *config.Config,
) (map[string]string, error) {
	storageTags := tags.ResourceTags(names.NewModelTag(cfg.UUID()), cfg)
	if storageInstance != nil {
		storageTags[tags.JujuStorageInstance] = storageInstance.Tag().Id()
		storageTags[tags.JujuStorageOwner] = storageInstance.Owner().Id()
	}
	return storageTags, nil
}

func volumeStorageAttachmentInfo(
	st StorageInterface,
	storageInstance state.StorageInstance,
	machineTag names.MachineTag,
) (*storage.StorageAttachmentInfo, error) {
	storageTag := storageInstance.StorageTag()
	volume, err := st.StorageInstanceVolume(storageTag)
	if err != nil {
		return nil, errors.Annotate(err, "getting volume")
	}
	volumeInfo, err := volume.Info()
	if err != nil {
		return nil, errors.Annotate(err, "getting volume info")
	}
	volumeAttachment, err := st.VolumeAttachment(machineTag, volume.VolumeTag())
	if err != nil {
		return nil, errors.Annotate(err, "getting volume attachment")
	}
	volumeAttachmentInfo, err := volumeAttachment.Info()
	if err != nil {
		return nil, errors.Annotate(err, "getting volume attachment info")
	}
	blockDevices, err := st.BlockDevices(machineTag)
	if err != nil {
		return nil, errors.Annotate(err, "getting block devices")
	}
	blockDevice, ok := MatchingBlockDevice(
		blockDevices,
		volumeInfo,
		volumeAttachmentInfo,
	)
	if !ok {
		// We must not say that a block-kind storage attachment is
		// provisioned until its block device has shown up on the
		// machine, otherwise the charm may attempt to use it and
		// fail.
		return nil, errors.NotProvisionedf("%v", names.ReadableString(storageTag))
	}
	devicePath, err := volumeAttachmentDevicePath(
		volumeInfo,
		volumeAttachmentInfo,
		*blockDevice,
	)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return &storage.StorageAttachmentInfo{
		storage.StorageKindBlock,
		devicePath,
	}, nil
}

// storageTags returns the tags that should be set on a volume or filesystem,
// if the provider supports them.
func storageTags(
	storageInstance state.StorageInstance,
	modelUUID, controllerUUID string,
	tagger tags.ResourceTagger,
) (map[string]string, error) {
	storageTags := tags.ResourceTags(
		names.NewModelTag(modelUUID),
		names.NewControllerTag(controllerUUID),
		tagger,
	)
	if storageInstance != nil {
		storageTags[tags.JujuStorageInstance] = storageInstance.Tag().Id()
		storageTags[tags.JujuStorageOwner] = storageInstance.Owner().Id()
	}
	return storageTags, nil
}

func filesystemStorageAttachmentInfo(
	st StorageInterface,
	storageInstance state.StorageInstance,
	machineTag names.MachineTag,
) (*storage.StorageAttachmentInfo, error) {
	storageTag := storageInstance.StorageTag()
	filesystem, err := st.StorageInstanceFilesystem(storageTag)
	if err != nil {
		return nil, errors.Annotate(err, "getting filesystem")
	}
	filesystemAttachment, err := st.FilesystemAttachment(machineTag, filesystem.FilesystemTag())
	if err != nil {
		return nil, errors.Annotate(err, "getting filesystem attachment")
	}
	filesystemAttachmentInfo, err := filesystemAttachment.Info()
	if err != nil {
		return nil, errors.Annotate(err, "getting filesystem attachment info")
	}
	return &storage.StorageAttachmentInfo{
		storage.StorageKindFilesystem,
		filesystemAttachmentInfo.MountPoint,
	}, nil
}

func createParamsStorageInstance(si state.StorageInstance, persistent bool) params.StorageDetails {
	result := params.StorageDetails{
		OwnerTag:   si.Owner().String(),
		StorageTag: si.Tag().String(),
		Kind:       params.StorageKind(si.Kind()),
		Status:     "pending",
		Persistent: persistent,
	}
	return result
}

func createStorageDetails(st storageAccess, si state.StorageInstance) (*params.StorageDetails, error) {
	// Get information from underlying volume or filesystem.
	var persistent bool
	var statusEntity status.StatusGetter
	if si.Kind() != state.StorageKindBlock {
		// TODO(axw) when we support persistent filesystems,
		// e.g. CephFS, we'll need to do set "persistent"
		// here too.
		filesystem, err := st.StorageInstanceFilesystem(si.StorageTag())
		if err != nil {
			return nil, errors.Trace(err)
		}
		statusEntity = filesystem
	} else {
		volume, err := st.StorageInstanceVolume(si.StorageTag())
		if err != nil {
			return nil, errors.Trace(err)
		}
		if info, err := volume.Info(); err == nil {
			persistent = info.Persistent
		}
		statusEntity = volume
	}
	status, err := statusEntity.Status()
	if err != nil {
		return nil, errors.Trace(err)
	}

	// Get unit storage attachments.
	var storageAttachmentDetails map[string]params.StorageAttachmentDetails
	storageAttachments, err := st.StorageAttachments(si.StorageTag())
	if err != nil {
		return nil, errors.Trace(err)
	}
	if len(storageAttachments) > 0 {
		storageAttachmentDetails = make(map[string]params.StorageAttachmentDetails)
		for _, a := range storageAttachments {
			machineTag, location, err := storageAttachmentInfo(st, a)
			if err != nil {
				return nil, errors.Trace(err)
			}
			details := params.StorageAttachmentDetails{
				a.StorageInstance().String(),
				a.Unit().String(),
				machineTag.String(),
				location,
			}
			storageAttachmentDetails[a.Unit().String()] = details
		}
	}

	return &params.StorageDetails{
		StorageTag:  si.Tag().String(),
		OwnerTag:    si.Owner().String(),
		Kind:        params.StorageKind(si.Kind()),
		Status:      common.EntityStatusFromState(status),
		Persistent:  persistent,
		Attachments: storageAttachmentDetails,
	}, nil
}