package tree

import (
	"context"
	"encoding/hex"
	"errors"
	"fmt"
	"io"
	"sort"
	"strconv"
	"strings"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/data"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer/frostfs"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer/tree"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/middleware"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/internal/logs"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/user"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"go.uber.org/zap"
	"golang.org/x/exp/maps"
)

type (
	Tree struct {
		service ServiceClient
		log     *zap.Logger
	}

	// ServiceClient is a client to interact with tree service.
	// Each method must return ErrNodeNotFound or ErrNodeAccessDenied if relevant.
	ServiceClient interface {
		GetNodes(ctx context.Context, p *GetNodesParams) ([]NodeResponse, error)
		GetSubTree(ctx context.Context, bktInfo *data.BucketInfo, treeID string, rootID []uint64, depth uint32, sort bool) ([]NodeResponse, error)
		GetSubTreeStream(ctx context.Context, bktInfo *data.BucketInfo, treeID string, rootID []uint64, depth uint32) (SubTreeStream, error)
		AddNode(ctx context.Context, bktInfo *data.BucketInfo, treeID string, parent uint64, meta map[string]string) (uint64, error)
		AddNodeByPath(ctx context.Context, bktInfo *data.BucketInfo, treeID string, path []string, meta map[string]string) (uint64, error)
		MoveNode(ctx context.Context, bktInfo *data.BucketInfo, treeID string, nodeID, parentID uint64, meta map[string]string) error
		RemoveNode(ctx context.Context, bktInfo *data.BucketInfo, treeID string, nodeID uint64) error
	}

	SubTreeStream interface {
		Next() (NodeResponse, error)
	}

	treeNode struct {
		ID        []uint64
		ParentID  []uint64
		ObjID     oid.ID
		TimeStamp []uint64
		Size      uint64
		Meta      map[string]string
	}

	multiSystemNode struct {
		// the first element is latest
		nodes []*treeNode
	}

	GetNodesParams struct {
		BktInfo    *data.BucketInfo
		TreeID     string
		Path       []string
		Meta       []string
		LatestOnly bool
		AllAttrs   bool
	}
)

const (
	FileNameKey = "FileName"
)

var (
	// ErrNodeNotFound is returned from ServiceClient in case of not found error.
	ErrNodeNotFound = tree.ErrNodeNotFound

	// ErrNodeAccessDenied is returned from ServiceClient service in case of access denied error.
	ErrNodeAccessDenied = tree.ErrNodeAccessDenied

	// ErrGatewayTimeout is returned from ServiceClient service in case of timeout error.
	ErrGatewayTimeout = frostfs.ErrGatewayTimeout

	errNodeDoesntContainFileName = errors.New("node doesn't contain FileName")

	errParentPathNotFound = errors.New("couldn't get parent path")
)

const (
	versioningKV        = "Versioning"
	cannedACLKV         = "cannedACL"
	ownerKeyKV          = "ownerKey"
	lockConfigurationKV = "LockConfiguration"
	oidKV               = "OID"
	cidKV               = "CID"

	isCombinedKV    = "IsCombined"
	isUnversionedKV = "IsUnversioned"
	isTagKV         = "IsTag"
	uploadIDKV      = "UploadId"
	partNumberKV    = "Number"
	sizeKV          = "Size"
	etagKV          = "ETag"
	md5KV           = "MD5"
	finishedKV      = "Finished"
	creationEpochKV = "CreationEpoch"

	// keys for lock.
	isLockKV       = "IsLock"
	legalHoldOIDKV = "LegalHoldOID"
	retentionOIDKV = "RetentionOID"
	untilDateKV    = "UntilDate"
	isComplianceKV = "IsCompliance"

	// keys for delete marker nodes.
	isDeleteMarkerKV = "IsDeleteMarker"
	ownerKV          = "Owner"
	createdKV        = "Created"

	settingsFileName        = "bucket-settings"
	corsFilename            = "bucket-cors"
	bucketTaggingFilename   = "bucket-tagging"
	bucketLifecycleFilename = "bucket-lifecycle"

	// versionTree -- ID of a tree with object versions.
	versionTree = "version"

	// systemTree -- ID of a tree with system objects
	// i.e. bucket settings with versioning and lock configuration, cors.
	systemTree = "system"

	separator            = "/"
	userDefinedTagPrefix = "User-Tag-"

	maxGetSubTreeDepth = 0 // means all subTree
)

// NewTree creates instance of Tree using provided address and create grpc connection.
func NewTree(service ServiceClient, log *zap.Logger) *Tree {
	return &Tree{
		service: service,
		log:     log,
	}
}

type Meta interface {
	GetKey() string
	GetValue() []byte
}

type NodeResponse interface {
	GetMeta() []Meta
	GetNodeID() []uint64
	GetParentID() []uint64
	GetTimestamp() []uint64
}

func newTreeNode(nodeInfo NodeResponse) (*treeNode, error) {
	if err := validateNodeResponse(nodeInfo); err != nil {
		return nil, err
	}

	tNode := &treeNode{
		ID:        nodeInfo.GetNodeID(),
		ParentID:  nodeInfo.GetParentID(),
		TimeStamp: nodeInfo.GetTimestamp(),
		Meta:      make(map[string]string, len(nodeInfo.GetMeta())),
	}

	for _, kv := range nodeInfo.GetMeta() {
		switch kv.GetKey() {
		case oidKV:
			if err := tNode.ObjID.DecodeString(string(kv.GetValue())); err != nil {
				return nil, err
			}
		case sizeKV:
			if sizeStr := string(kv.GetValue()); len(sizeStr) > 0 {
				var err error
				if tNode.Size, err = strconv.ParseUint(sizeStr, 10, 64); err != nil {
					return nil, fmt.Errorf("invalid size value '%s': %w", sizeStr, err)
				}
			}
		default:
			tNode.Meta[kv.GetKey()] = string(kv.GetValue())
		}
	}

	return tNode, nil
}

func (n *treeNode) Get(key string) (string, bool) {
	value, ok := n.Meta[key]
	return value, ok
}

func (n *treeNode) FileName() (string, bool) {
	value, ok := n.Meta[FileNameKey]
	return value, ok
}

func (n *treeNode) IsSplit() bool {
	return len(n.ID) != 1 || len(n.ParentID) != 1 || len(n.TimeStamp) != 1
}

func (n *treeNode) GetLatestNodeIndex() int {
	var (
		maxTimestamp uint64
		index        int
	)

	for i, timestamp := range n.TimeStamp {
		if timestamp > maxTimestamp {
			maxTimestamp = timestamp
			index = i
		}
	}

	return index
}

func newNodeVersion(log *zap.Logger, filePath string, node NodeResponse) (*data.NodeVersion, error) {
	tNode, err := newTreeNode(node)
	if err != nil {
		return nil, fmt.Errorf("invalid tree node: %w", err)
	}

	return newNodeVersionFromTreeNode(log, filePath, tNode)
}

func newNodeVersionFromTreeNode(log *zap.Logger, filePath string, treeNode *treeNode) (*data.NodeVersion, error) {
	_, isUnversioned := treeNode.Get(isUnversionedKV)
	_, isDeleteMarker := treeNode.Get(isDeleteMarkerKV)
	_, isCombined := treeNode.Get(isCombinedKV)
	eTag, _ := treeNode.Get(etagKV)
	md5, _ := treeNode.Get(md5KV)

	if treeNode.IsSplit() {
		return nil, errors.New("invalid version tree node: this is split node")
	}

	version := &data.NodeVersion{
		BaseNodeVersion: data.BaseNodeVersion{
			ID:             treeNode.ID[0],
			ParenID:        treeNode.ParentID[0],
			OID:            treeNode.ObjID,
			Timestamp:      treeNode.TimeStamp[0],
			ETag:           eTag,
			MD5:            md5,
			Size:           treeNode.Size,
			FilePath:       filePath,
			IsDeleteMarker: isDeleteMarker,
		},
		IsUnversioned: isUnversioned,
		IsCombined:    isCombined,
	}

	if createdStr, ok := treeNode.Get(createdKV); ok {
		if utcMilli, err := strconv.ParseInt(createdStr, 10, 64); err != nil {
			log.Warn(logs.InvalidTreeKV, zap.String(createdKV, createdStr), zap.Error(err))
		} else {
			created := time.UnixMilli(utcMilli)
			version.Created = &created
		}
	}

	if ownerStr, ok := treeNode.Get(ownerKV); ok {
		var owner user.ID
		if err := owner.DecodeString(ownerStr); err != nil {
			log.Warn(logs.InvalidTreeKV, zap.String(ownerKV, ownerStr), zap.Error(err))
		} else {
			version.Owner = &owner
		}
	}

	if creationEpoch, ok := treeNode.Get(creationEpochKV); ok {
		if epoch, err := strconv.ParseUint(creationEpoch, 10, 64); err != nil {
			log.Warn(logs.InvalidTreeKV, zap.String(creationEpochKV, creationEpoch), zap.Error(err))
		} else {
			version.CreationEpoch = epoch
		}
	}

	return version, nil
}

func newMultiNode(nodes []NodeResponse) (*multiSystemNode, error) {
	var (
		err          error
		index        int
		maxTimestamp uint64
	)

	if len(nodes) == 0 {
		return nil, errors.New("multi node must have at least one node")
	}

	treeNodes := make([]*treeNode, len(nodes))

	for i, node := range nodes {
		if treeNodes[i], err = newTreeNode(node); err != nil {
			return nil, fmt.Errorf("parse system node response: %w", err)
		}

		if timestamp := getMaxTimestamp(node); timestamp > maxTimestamp {
			index = i
			maxTimestamp = timestamp
		}
	}

	treeNodes[0], treeNodes[index] = treeNodes[index], treeNodes[0]

	return &multiSystemNode{
		nodes: treeNodes,
	}, nil
}

func (m *multiSystemNode) Latest() *treeNode {
	return m.nodes[0]
}

func (m *multiSystemNode) Old() []*treeNode {
	return m.nodes[1:]
}

func newMultipartInfoFromTreeNode(log *zap.Logger, filePath string, treeNode *treeNode) (*data.MultipartInfo, error) {
	uploadID, _ := treeNode.Get(uploadIDKV)
	if uploadID == "" {
		return nil, fmt.Errorf("it's not a multipart node: missing UploadId")
	}

	if treeNode.IsSplit() {
		return nil, fmt.Errorf("invalid multipart node '%s': tree node is split", filePath)
	}

	multipartInfo := &data.MultipartInfo{
		ID:       treeNode.ID[0],
		Key:      filePath,
		UploadID: uploadID,
		Meta:     treeNode.Meta,
	}

	if ownerID, ok := treeNode.Get(ownerKV); ok {
		if err := multipartInfo.Owner.DecodeString(ownerID); err != nil {
			log.Warn(logs.InvalidTreeKV, zap.String(ownerKV, ownerID), zap.Error(err))
		}
	}

	if created, ok := treeNode.Get(createdKV); ok {
		if utcMilli, err := strconv.ParseInt(created, 10, 64); err != nil {
			log.Warn(logs.InvalidTreeKV, zap.String(createdKV, created), zap.Error(err))
		} else {
			multipartInfo.Created = time.UnixMilli(utcMilli)
		}
	}

	if finished, ok := treeNode.Get(finishedKV); ok {
		if flag, err := strconv.ParseBool(finished); err != nil {
			log.Warn(logs.InvalidTreeKV, zap.String(finishedKV, finished), zap.Error(err))
		} else {
			multipartInfo.Finished = flag
		}
	}

	if creationEpoch, ok := treeNode.Get(creationEpochKV); ok {
		if epoch, err := strconv.ParseUint(creationEpoch, 10, 64); err != nil {
			log.Warn(logs.InvalidTreeKV, zap.String(creationEpochKV, creationEpoch), zap.Error(err))
		} else {
			multipartInfo.CreationEpoch = epoch
		}
	}

	return multipartInfo, nil
}

func newMultipartInfo(log *zap.Logger, node NodeResponse) (*data.MultipartInfo, error) {
	if err := validateNodeResponse(node); err != nil {
		return nil, err
	}

	if len(node.GetNodeID()) != 1 {
		return nil, errors.New("invalid multipart node: this is split node")
	}

	multipartInfo := &data.MultipartInfo{
		ID:   node.GetNodeID()[0],
		Meta: make(map[string]string, len(node.GetMeta())),
	}

	for _, kv := range node.GetMeta() {
		switch kv.GetKey() {
		case uploadIDKV:
			multipartInfo.UploadID = string(kv.GetValue())
		case FileNameKey:
			multipartInfo.Key = string(kv.GetValue())
		case createdKV:
			if utcMilli, err := strconv.ParseInt(string(kv.GetValue()), 10, 64); err != nil {
				log.Warn(logs.InvalidTreeKV, zap.String(createdKV, string(kv.GetValue())), zap.Error(err))
			} else {
				multipartInfo.Created = time.UnixMilli(utcMilli)
			}
		case ownerKV:
			if err := multipartInfo.Owner.DecodeString(string(kv.GetValue())); err != nil {
				log.Warn(logs.InvalidTreeKV, zap.String(ownerKV, string(kv.GetValue())), zap.Error(err))
			}
		case finishedKV:
			if isFinished, err := strconv.ParseBool(string(kv.GetValue())); err != nil {
				log.Warn(logs.InvalidTreeKV, zap.String(finishedKV, string(kv.GetValue())), zap.Error(err))
			} else {
				multipartInfo.Finished = isFinished
			}
		case creationEpochKV:
			if epoch, err := strconv.ParseUint(string(kv.GetValue()), 10, 64); err != nil {
				log.Warn(logs.InvalidTreeKV, zap.String(creationEpochKV, string(kv.GetValue())), zap.Error(err))
			} else {
				multipartInfo.CreationEpoch = epoch
			}
		default:
			multipartInfo.Meta[kv.GetKey()] = string(kv.GetValue())
		}
	}

	if multipartInfo.UploadID == "" {
		return nil, fmt.Errorf("it's not a multipart node")
	}

	return multipartInfo, nil
}

func validateNodeResponse(node NodeResponse) error {
	ids := node.GetNodeID()
	parentIDs := node.GetParentID()
	timestamps := node.GetTimestamp()

	if len(ids) == 0 || len(parentIDs) == 0 || len(timestamps) == 0 {
		return errors.New("invalid node response: missing ids")
	}

	if len(ids) != len(parentIDs) || len(parentIDs) != len(timestamps) {
		return errors.New("invalid node response: multiple ids length mismatch")
	}

	return nil
}

func newPartInfo(node NodeResponse) (*data.PartInfoExtended, error) {
	if err := validateNodeResponse(node); err != nil {
		return nil, err
	}

	if len(node.GetNodeID()) != 1 {
		return nil, errors.New("invalid part node: this is split node")
	}

	partInfo := &data.PartInfoExtended{
		Timestamp: node.GetTimestamp()[0],
	}

	var err error
	for _, kv := range node.GetMeta() {
		value := string(kv.GetValue())
		switch kv.GetKey() {
		case partNumberKV:
			if partInfo.Number, err = strconv.Atoi(value); err != nil {
				return nil, fmt.Errorf("invalid part number: %w", err)
			}
		case oidKV:
			if err = partInfo.OID.DecodeString(value); err != nil {
				return nil, fmt.Errorf("invalid oid: %w", err)
			}
		case etagKV:
			partInfo.ETag = value
		case sizeKV:
			if partInfo.Size, err = strconv.ParseUint(value, 10, 64); err != nil {
				return nil, fmt.Errorf("invalid part size: %w", err)
			}
		case createdKV:
			var utcMilli int64
			if utcMilli, err = strconv.ParseInt(value, 10, 64); err != nil {
				return nil, fmt.Errorf("invalid created timestamp: %w", err)
			}
			partInfo.Created = time.UnixMilli(utcMilli)
		case md5KV:
			partInfo.MD5 = value
		}
	}

	if partInfo.Number <= 0 {
		return nil, fmt.Errorf("it's not a part node")
	}

	return partInfo, nil
}

func (c *Tree) GetSettingsNode(ctx context.Context, bktInfo *data.BucketInfo) (*data.BucketSettings, error) {
	multiNode, err := c.getSystemNode(ctx, bktInfo, settingsFileName)
	if err != nil {
		return nil, fmt.Errorf("couldn't get node: %w", err)
	}

	node := multiNode.Latest()

	settings := &data.BucketSettings{Versioning: data.VersioningUnversioned}
	if versioningValue, ok := node.Get(versioningKV); ok {
		settings.Versioning = versioningValue
	}

	if lockConfigurationValue, ok := node.Get(lockConfigurationKV); ok {
		if settings.LockConfiguration, err = parseLockConfiguration(lockConfigurationValue); err != nil {
			return nil, fmt.Errorf("settings node: invalid lock configuration: %w", err)
		}
	}

	settings.CannedACL, _ = node.Get(cannedACLKV)

	if ownerKeyHex, ok := node.Get(ownerKeyKV); ok {
		if settings.OwnerKey, err = keys.NewPublicKeyFromString(ownerKeyHex); err != nil {
			c.reqLogger(ctx).Error(logs.SettingsNodeInvalidOwnerKey, zap.Error(err))
		}
	}

	return settings, nil
}

func (c *Tree) PutSettingsNode(ctx context.Context, bktInfo *data.BucketInfo, settings *data.BucketSettings) error {
	multiNode, err := c.getSystemNode(ctx, bktInfo, settingsFileName)
	isErrNotFound := errors.Is(err, tree.ErrNodeNotFound)
	if err != nil && !isErrNotFound {
		return fmt.Errorf("couldn't get node: %w", err)
	}

	meta := metaFromSettings(settings)

	if isErrNotFound {
		_, err = c.service.AddNode(ctx, bktInfo, systemTree, 0, meta)
		return err
	}

	latest := multiNode.Latest()
	ind := latest.GetLatestNodeIndex()
	if latest.IsSplit() {
		c.reqLogger(ctx).Error(logs.BucketSettingsNodeHasMultipleIDs, zap.Uint64s("ids", latest.ID))
	}

	if err = c.service.MoveNode(ctx, bktInfo, systemTree, latest.ID[ind], 0, meta); err != nil {
		return fmt.Errorf("move settings node: %w", err)
	}

	c.cleanOldNodes(ctx, multiNode.Old(), bktInfo)

	return nil
}

func (c *Tree) GetBucketCORS(ctx context.Context, bktInfo *data.BucketInfo) (oid.Address, error) {
	node, err := c.getSystemNode(ctx, bktInfo, corsFilename)
	if err != nil {
		return oid.Address{}, err
	}

	return getTreeNodeAddress(node.Latest())
}

func (c *Tree) PutBucketCORS(ctx context.Context, bktInfo *data.BucketInfo, addr oid.Address) ([]oid.Address, error) {
	multiNode, err := c.getSystemNode(ctx, bktInfo, corsFilename)
	isErrNotFound := errors.Is(err, tree.ErrNodeNotFound)
	if err != nil && !isErrNotFound {
		return nil, fmt.Errorf("couldn't get node: %w", err)
	}

	meta := make(map[string]string)
	meta[FileNameKey] = corsFilename
	meta[oidKV] = addr.Object().EncodeToString()
	meta[cidKV] = addr.Container().EncodeToString()

	if isErrNotFound {
		if _, err = c.service.AddNode(ctx, bktInfo, systemTree, 0, meta); err != nil {
			return nil, err
		}
		return nil, tree.ErrNoNodeToRemove
	}

	latest := multiNode.Latest()
	ind := latest.GetLatestNodeIndex()
	if latest.IsSplit() {
		c.reqLogger(ctx).Error(logs.BucketCORSNodeHasMultipleIDs)
	}

	if err = c.service.MoveNode(ctx, bktInfo, systemTree, latest.ID[ind], 0, meta); err != nil {
		return nil, fmt.Errorf("move cors node: %w", err)
	}

	objToDelete := make([]oid.Address, 1, len(multiNode.nodes))
	objToDelete[0], err = getTreeNodeAddress(latest)
	if err != nil {
		return nil, fmt.Errorf("parse object addr of latest cors node in tree: %w", err)
	}

	objToDelete = append(objToDelete, c.cleanOldNodes(ctx, multiNode.Old(), bktInfo)...)

	return objToDelete, nil
}

func (c *Tree) DeleteBucketCORS(ctx context.Context, bktInfo *data.BucketInfo) ([]oid.Address, error) {
	multiNode, err := c.getSystemNode(ctx, bktInfo, corsFilename)
	isErrNotFound := errors.Is(err, tree.ErrNodeNotFound)
	if err != nil && !isErrNotFound {
		return nil, err
	}

	if isErrNotFound {
		return nil, tree.ErrNoNodeToRemove
	}

	objToDelete := c.cleanOldNodes(ctx, multiNode.nodes, bktInfo)
	if len(objToDelete) != len(multiNode.nodes) {
		return nil, fmt.Errorf("failed to clean all old cors nodes")
	}

	return objToDelete, nil
}

func getTreeNodeAddress(node *treeNode) (oid.Address, error) {
	var addr oid.Address
	addr.SetObject(node.ObjID)

	if cidStr, ok := node.Get(cidKV); ok {
		var cnrID cid.ID
		if err := cnrID.DecodeString(cidStr); err != nil {
			return oid.Address{}, fmt.Errorf("couldn't decode cid: %w", err)
		}
		addr.SetContainer(cnrID)
	}

	return addr, nil
}

func (c *Tree) cleanOldNodes(ctx context.Context, nodes []*treeNode, bktInfo *data.BucketInfo) []oid.Address {
	res := make([]oid.Address, 0, len(nodes))

	for _, node := range nodes {
		ind := node.GetLatestNodeIndex()
		if node.IsSplit() {
			c.reqLogger(ctx).Error(logs.SystemNodeHasMultipleIDs, zap.String("FileName", node.Meta[FileNameKey]), zap.Uint64s("ids", node.ID))
		}
		if err := c.service.RemoveNode(ctx, bktInfo, systemTree, node.ID[ind]); err != nil {
			c.reqLogger(ctx).Warn(logs.FailedToRemoveOldSystemNode, zap.String("FileName", node.Meta[FileNameKey]), zap.Uint64("id", node.ID[ind]))
		} else {
			addr, err := getTreeNodeAddress(node)
			if err != nil {
				c.log.Warn(logs.FailedToParseAddressInTreeNode, zap.String("FileName", node.Meta[FileNameKey]), zap.Uint64("id", node.ID[ind]))
				continue
			}
			res = append(res, addr)
		}
	}

	return res
}

func (c *Tree) GetObjectTagging(ctx context.Context, bktInfo *data.BucketInfo, objVersion *data.NodeVersion) (map[string]string, error) {
	tagNode, err := c.getTreeNode(ctx, bktInfo, objVersion.ID, isTagKV)
	if err != nil {
		return nil, err
	}

	return getObjectTagging(tagNode), nil
}

func getObjectTagging(tagNode *treeNode) map[string]string {
	if tagNode == nil {
		return nil
	}

	meta := make(map[string]string)

	for key, val := range tagNode.Meta {
		if strings.HasPrefix(key, userDefinedTagPrefix) {
			meta[strings.TrimPrefix(key, userDefinedTagPrefix)] = val
		}
	}

	return meta
}

func (c *Tree) PutObjectTagging(ctx context.Context, bktInfo *data.BucketInfo, objVersion *data.NodeVersion, tagSet map[string]string) error {
	tagNode, err := c.getTreeNode(ctx, bktInfo, objVersion.ID, isTagKV)
	if err != nil {
		return err
	}

	treeTagSet := make(map[string]string)
	treeTagSet[isTagKV] = "true"

	for key, val := range tagSet {
		treeTagSet[userDefinedTagPrefix+key] = val
	}

	if tagNode == nil {
		_, err = c.service.AddNode(ctx, bktInfo, versionTree, objVersion.ID, treeTagSet)
		return err
	}

	ind := tagNode.GetLatestNodeIndex()
	if tagNode.IsSplit() {
		c.reqLogger(ctx).Error(logs.ObjectTaggingNodeHasMultipleIDs)
	}

	return c.service.MoveNode(ctx, bktInfo, versionTree, tagNode.ID[ind], objVersion.ID, treeTagSet)
}

func (c *Tree) DeleteObjectTagging(ctx context.Context, bktInfo *data.BucketInfo, objVersion *data.NodeVersion) error {
	return c.PutObjectTagging(ctx, bktInfo, objVersion, nil)
}

func (c *Tree) GetBucketTagging(ctx context.Context, bktInfo *data.BucketInfo) (map[string]string, error) {
	multiNode, err := c.getSystemNode(ctx, bktInfo, bucketTaggingFilename)
	if err != nil {
		return nil, err
	}

	tags := make(map[string]string)

	for key, val := range multiNode.Latest().Meta {
		if strings.HasPrefix(key, userDefinedTagPrefix) {
			tags[strings.TrimPrefix(key, userDefinedTagPrefix)] = val
		}
	}

	return tags, nil
}

func (c *Tree) PutBucketTagging(ctx context.Context, bktInfo *data.BucketInfo, tagSet map[string]string) error {
	multiNode, err := c.getSystemNode(ctx, bktInfo, bucketTaggingFilename)
	isErrNotFound := errors.Is(err, tree.ErrNodeNotFound)
	if err != nil && !isErrNotFound {
		return fmt.Errorf("couldn't get node: %w", err)
	}

	treeTagSet := make(map[string]string)
	treeTagSet[FileNameKey] = bucketTaggingFilename

	for key, val := range tagSet {
		treeTagSet[userDefinedTagPrefix+key] = val
	}

	if isErrNotFound {
		_, err = c.service.AddNode(ctx, bktInfo, systemTree, 0, treeTagSet)
		return err
	}

	latest := multiNode.Latest()
	ind := latest.GetLatestNodeIndex()
	if latest.IsSplit() {
		c.reqLogger(ctx).Error(logs.BucketTaggingNodeHasMultipleIDs, zap.Uint64s("ids", latest.ID))
	}

	if err = c.service.MoveNode(ctx, bktInfo, systemTree, latest.ID[ind], 0, treeTagSet); err != nil {
		return fmt.Errorf("move bucket tagging node: %w", err)
	}

	c.cleanOldNodes(ctx, multiNode.Old(), bktInfo)

	return nil
}

func (c *Tree) DeleteBucketTagging(ctx context.Context, bktInfo *data.BucketInfo) error {
	return c.PutBucketTagging(ctx, bktInfo, nil)
}

func (c *Tree) getTreeNode(ctx context.Context, bktInfo *data.BucketInfo, nodeID uint64, key string) (*treeNode, error) {
	nodes, err := c.getTreeNodes(ctx, bktInfo, nodeID, key)
	if err != nil {
		return nil, err
	}
	// if there will be many allocations, consider having separate
	// implementations of 'getTreeNode' and 'getTreeNodes'
	return nodes[key], nil
}

func (c *Tree) getTreeNodes(ctx context.Context, bktInfo *data.BucketInfo, nodeID uint64, keys ...string) (map[string]*treeNode, error) {
	subtree, err := c.service.GetSubTree(ctx, bktInfo, versionTree, []uint64{nodeID}, 2, false)
	if err != nil {
		return nil, err
	}

	// consider using map[string][]*treeNode
	// to be able to remove unused node, that can be added during split
	treeNodes := make(map[string]*treeNode, len(keys))

	for _, s := range subtree {
		node, err := newTreeNode(s)
		if err != nil {
			return nil, err
		}
		for _, key := range keys {
			if _, ok := node.Get(key); ok {
				treeNodes[key] = node
				break
			}
		}
		if len(treeNodes) == len(keys) {
			break
		}
	}

	return treeNodes, nil
}

func (c *Tree) GetVersions(ctx context.Context, bktInfo *data.BucketInfo, filepath string) ([]*data.NodeVersion, error) {
	return c.getVersions(ctx, bktInfo, versionTree, filepath, false)
}

func (c *Tree) GetLatestVersion(ctx context.Context, bktInfo *data.BucketInfo, objectName string) (*data.NodeVersion, error) {
	meta := []string{oidKV, isCombinedKV, isUnversionedKV, isDeleteMarkerKV, etagKV, sizeKV, md5KV, creationEpochKV}
	path := pathFromName(objectName)

	p := &GetNodesParams{
		BktInfo:    bktInfo,
		TreeID:     versionTree,
		Path:       path,
		Meta:       meta,
		LatestOnly: false,
		AllAttrs:   false,
	}
	nodes, err := c.service.GetNodes(ctx, p)
	if err != nil {
		return nil, err
	}

	latestNode, err := getLatestVersionNode(nodes)
	if err != nil {
		return nil, err
	}

	return newNodeVersion(c.reqLogger(ctx), objectName, latestNode)
}

func getLatestVersionNode(nodes []NodeResponse) (NodeResponse, error) {
	var (
		maxCreationTime uint64
		targetIndexNode = -1
	)

	for i, node := range nodes {
		if !checkExistOID(node.GetMeta()) {
			continue
		}

		if currentCreationTime := getMaxTimestamp(node); currentCreationTime > maxCreationTime {
			targetIndexNode = i
			maxCreationTime = currentCreationTime
		}
	}

	if targetIndexNode == -1 {
		return nil, tree.ErrNodeNotFound
	}

	return nodes[targetIndexNode], nil
}

func getMaxTimestamp(node NodeResponse) uint64 {
	var maxTimestamp uint64

	for _, timestamp := range node.GetTimestamp() {
		if timestamp > maxTimestamp {
			maxTimestamp = timestamp
		}
	}

	return maxTimestamp
}

func checkExistOID(meta []Meta) bool {
	for _, kv := range meta {
		if kv.GetKey() == "OID" {
			return true
		}
	}

	return false
}

// pathFromName splits name by '/'.
func pathFromName(objectName string) []string {
	return strings.Split(objectName, separator)
}

type DummySubTreeStream struct {
	data NodeResponse
	read bool
}

func (s *DummySubTreeStream) Next() (NodeResponse, error) {
	if s.read {
		return nil, io.EOF
	}

	s.read = true
	return s.data, nil
}

type MultiID []uint64

func (m MultiID) Equal(id MultiID) bool {
	seen := make(map[uint64]struct{}, len(m))

	for i := range m {
		seen[m[i]] = struct{}{}
	}

	for i := range id {
		if _, ok := seen[id[i]]; !ok {
			return false
		}
	}

	return true
}

type VersionsByPrefixStreamImpl struct {
	ctx                context.Context
	rootID             MultiID
	intermediateRootID MultiID
	service            ServiceClient
	bktInfo            *data.BucketInfo
	mainStream         SubTreeStream
	innerStream        SubTreeStream
	headPrefix         string
	tailPrefix         string
	namesMap           map[uint64]string
	ended              bool
	latestOnly         bool
	currentLatest      *data.NodeVersion
	log                *zap.Logger
}

func (s *VersionsByPrefixStreamImpl) Next(context.Context) (*data.NodeVersion, error) {
	if s.ended {
		return nil, io.EOF
	}

	for {
		if s.innerStream == nil {
			node, err := s.getNodeFromMainStream()
			if err != nil {
				if errors.Is(err, io.EOF) {
					s.ended = true
					if s.currentLatest != nil {
						return s.currentLatest, nil
					}
				}
				return nil, fmt.Errorf("get node from main stream: %w", err)
			}

			if err = s.initInnerStream(node); err != nil {
				return nil, fmt.Errorf("init inner stream: %w", err)
			}
		}

		nodeVersion, err := s.getNodeVersionFromInnerStream()
		if err != nil {
			if errors.Is(err, io.EOF) {
				s.innerStream = nil
				maps.Clear(s.namesMap)
				if s.currentLatest != nil && !s.intermediateRootID.Equal([]uint64{s.currentLatest.ID}) {
					return s.currentLatest, nil
				}
				continue
			}
			return nil, fmt.Errorf("inner stream: %w", err)
		}
		return nodeVersion, nil
	}
}

func (s *VersionsByPrefixStreamImpl) getNodeFromMainStream() (NodeResponse, error) {
	for {
		node, err := s.mainStream.Next()
		if err != nil {
			if errors.Is(err, tree.ErrNodeNotFound) {
				return nil, io.EOF
			}
			return nil, fmt.Errorf("main stream next: %w", err)
		}

		if !s.rootID.Equal(node.GetNodeID()) && strings.HasPrefix(getFilename(node), s.tailPrefix) {
			return node, nil
		}
	}
}

func (s *VersionsByPrefixStreamImpl) initInnerStream(node NodeResponse) (err error) {
	if s.rootID.Equal(node.GetParentID()) {
		s.intermediateRootID = node.GetNodeID()
	}

	if isIntermediate(node) {
		s.innerStream, err = s.service.GetSubTreeStream(s.ctx, s.bktInfo, versionTree, node.GetNodeID(), maxGetSubTreeDepth)
		if err != nil {
			return fmt.Errorf("get sub tree node from main stream: %w", err)
		}
	} else {
		s.innerStream = &DummySubTreeStream{data: node}
	}

	return nil
}

func (s *VersionsByPrefixStreamImpl) getNodeVersionFromInnerStream() (*data.NodeVersion, error) {
	for {
		node, err := s.innerStream.Next()
		if err != nil {
			return nil, fmt.Errorf("inner stream: %w", err)
		}

		nodeVersion, skip, err := s.parseNodeResponse(node)
		if err != nil {
			return nil, err
		}
		if skip {
			continue
		}

		if s.latestOnly {
			if s.currentLatest == nil {
				s.currentLatest = nodeVersion
				continue
			}

			if s.currentLatest.FilePath != nodeVersion.FilePath {
				res := s.currentLatest
				s.currentLatest = nodeVersion
				return res, nil
			}

			if s.currentLatest.Timestamp < nodeVersion.Timestamp {
				s.currentLatest = nodeVersion
			}

			continue
		}

		return nodeVersion, nil
	}
}

func (s *VersionsByPrefixStreamImpl) parseNodeResponse(node NodeResponse) (res *data.NodeVersion, skip bool, err error) {
	trNode, fileName, err := parseTreeNode(node)
	if err != nil {
		if !errors.Is(err, errNodeDoesntContainFileName) {
			s.log.Debug(logs.ParseTreeNode, zap.Error(err))
		}
		return nil, true, nil
	}

	var parentPrefix string
	if s.headPrefix != "" { // The root of subTree can also have a parent
		parentPrefix = strings.TrimSuffix(s.headPrefix, separator) + separator // To avoid 'foo//bar'
	}

	var filepath string
	if !s.intermediateRootID.Equal(trNode.ID) {
		if filepath, err = formFilePath(trNode, fileName, s.namesMap); err != nil {
			return nil, false, fmt.Errorf("invalid node order: %w", err)
		}
	} else {
		filepath = parentPrefix + fileName
		for _, id := range trNode.ID {
			s.namesMap[id] = filepath
		}
	}

	if trNode.ObjID.Equals(oid.ID{}) { // The node can be intermediate, but we still want to update namesMap
		return nil, true, nil
	}

	nodeVersion, err := newNodeVersionFromTreeNode(s.log, filepath, trNode)
	return nodeVersion, false, err
}

func (c *Tree) InitVersionsByPrefixStream(ctx context.Context, bktInfo *data.BucketInfo, prefix string, latestOnly bool) (data.VersionsStream, error) {
	mainStream, tailPrefix, rootID, err := c.getSubTreeByPrefixMainStream(ctx, bktInfo, versionTree, prefix)
	if err != nil {
		if errors.Is(err, io.EOF) {
			return &VersionsByPrefixStreamImpl{ended: true}, nil
		}
		return nil, err
	}

	return &VersionsByPrefixStreamImpl{
		ctx:        ctx,
		namesMap:   map[uint64]string{},
		rootID:     rootID,
		service:    c.service,
		bktInfo:    bktInfo,
		mainStream: mainStream,
		headPrefix: strings.TrimSuffix(prefix, tailPrefix),
		tailPrefix: tailPrefix,
		latestOnly: latestOnly,
		log:        c.reqLogger(ctx),
	}, nil
}

func (c *Tree) getSubTreeByPrefixMainStream(ctx context.Context, bktInfo *data.BucketInfo, treeID, prefix string) (SubTreeStream, string, []uint64, error) {
	rootID, tailPrefix, err := c.determinePrefixNode(ctx, bktInfo, treeID, prefix)
	if err != nil {
		if errors.Is(err, tree.ErrNodeNotFound) {
			return nil, "", nil, io.EOF
		}
		return nil, "", nil, err
	}

	subTree, err := c.service.GetSubTreeStream(ctx, bktInfo, treeID, rootID, 2)
	if err != nil {
		if errors.Is(err, tree.ErrNodeNotFound) {
			return nil, "", nil, io.EOF
		}
		return nil, "", nil, err
	}

	return subTree, tailPrefix, rootID, nil
}

func (c *Tree) determinePrefixNode(ctx context.Context, bktInfo *data.BucketInfo, treeID, prefix string) ([]uint64, string, error) {
	rootID := []uint64{0}
	path := strings.Split(prefix, separator)
	tailPrefix := path[len(path)-1]

	if len(path) > 1 {
		var err error
		rootID, err = c.getPrefixNodeID(ctx, bktInfo, treeID, path[:len(path)-1])
		if err != nil {
			return nil, "", err
		}
	}

	return rootID, tailPrefix, nil
}

func (c *Tree) getPrefixNodeID(ctx context.Context, bktInfo *data.BucketInfo, treeID string, prefixPath []string) ([]uint64, error) {
	p := &GetNodesParams{
		BktInfo:    bktInfo,
		TreeID:     treeID,
		Path:       prefixPath,
		LatestOnly: false,
		AllAttrs:   true,
	}
	nodes, err := c.service.GetNodes(ctx, p)
	if err != nil {
		return nil, err
	}

	var intermediateNodes []uint64
	for _, node := range nodes {
		if isIntermediate(node) {
			intermediateNodes = append(intermediateNodes, node.GetNodeID()...)
		}
	}

	if len(intermediateNodes) == 0 {
		return nil, tree.ErrNodeNotFound
	}

	return intermediateNodes, nil
}

func (c *Tree) getSubTreeByPrefixStream(ctx context.Context, bktInfo *data.BucketInfo, treeID, prefix string) (SubTreeStream, []uint64, error) {
	rootID, _, err := c.determinePrefixNode(ctx, bktInfo, treeID, prefix)
	if err != nil {
		if errors.Is(err, tree.ErrNodeNotFound) {
			return nil, nil, nil
		}
		return nil, nil, err
	}

	stream, err := c.service.GetSubTreeStream(ctx, bktInfo, treeID, rootID, 2)

	return stream, rootID, err
}

func getFilename(node NodeResponse) string {
	for _, kv := range node.GetMeta() {
		if kv.GetKey() == FileNameKey {
			return string(kv.GetValue())
		}
	}

	return ""
}

func isIntermediate(node NodeResponse) bool {
	if len(node.GetMeta()) != 1 {
		return false
	}

	return node.GetMeta()[0].GetKey() == FileNameKey
}

func formFilePath(node *treeNode, fileName string, namesMap map[uint64]string) (string, error) {
	var filePath string

	for i, id := range node.ParentID {
		parentPath, ok := namesMap[id]
		if !ok {
			return "", errParentPathNotFound
		}
		filePath = parentPath + separator + fileName
		namesMap[node.ID[i]] = filePath
	}

	return filePath, nil
}

func parseTreeNode(node NodeResponse) (*treeNode, string, error) {
	tNode, err := newTreeNode(node)
	if err != nil { // invalid OID attribute
		return nil, "", err
	}

	fileName, ok := tNode.FileName()
	if !ok {
		return nil, "", errNodeDoesntContainFileName
	}

	return tNode, fileName, nil
}

func (c *Tree) GetUnversioned(ctx context.Context, bktInfo *data.BucketInfo, filepath string) (*data.NodeVersion, error) {
	return c.getUnversioned(ctx, bktInfo, versionTree, filepath)
}

func (c *Tree) getUnversioned(ctx context.Context, bktInfo *data.BucketInfo, treeID, filepath string) (*data.NodeVersion, error) {
	nodes, err := c.getVersions(ctx, bktInfo, treeID, filepath, true)
	if err != nil {
		return nil, err
	}

	if len(nodes) == 0 {
		return nil, tree.ErrNodeNotFound
	}

	if len(nodes) > 1 {
		c.reqLogger(ctx).Debug(logs.FoundMoreThanOneUnversionedNode,
			zap.String("treeID", treeID), zap.String("filepath", filepath))
	}

	sort.Slice(nodes, func(i, j int) bool {
		return nodes[i].Timestamp > nodes[j].Timestamp
	})

	return nodes[0], nil
}

func (c *Tree) AddVersion(ctx context.Context, bktInfo *data.BucketInfo, version *data.NodeVersion) (uint64, error) {
	return c.addVersion(ctx, bktInfo, versionTree, version)
}

func (c *Tree) RemoveVersion(ctx context.Context, bktInfo *data.BucketInfo, id uint64) error {
	return c.service.RemoveNode(ctx, bktInfo, versionTree, id)
}

func (c *Tree) CreateMultipartUpload(ctx context.Context, bktInfo *data.BucketInfo, info *data.MultipartInfo) error {
	path := pathFromName(info.Key)
	meta := metaFromMultipart(info, path[len(path)-1])
	_, err := c.service.AddNodeByPath(ctx, bktInfo, systemTree, path[:len(path)-1], meta)

	return err
}

type multipartInfoStream struct {
	log       *zap.Logger
	nodePaths map[uint64]string
	rootID    MultiID
	// childStream stream of children nodes of prefix node.
	childStream SubTreeStream
	// currentStream stream of children's nodes with max depth.
	currentStream SubTreeStream
	treeService   ServiceClient
	bktInfo       *data.BucketInfo
	uploadID      string
	keyMarker     string
	headPrefix    string
	prefix        string
}

func (m *multipartInfoStream) Next(ctx context.Context) (*data.MultipartInfo, error) {
	var tNode *treeNode
	var filePath string

	if m.currentStream == nil {
		var err error
		if m.currentStream, err = m.openNewStream(ctx); err != nil {
			return nil, err
		}
	}
	for {
		var err error
		tNode, err = getTreeNodeFromStream(m.currentStream)
		if err != nil {
			if errors.Is(err, io.EOF) {
				if m.currentStream, err = m.openNewStream(ctx); err != nil {
					return nil, err
				}
				continue
			}
			return nil, err
		}
		var ok bool
		if filePath, ok = m.checkTreeNode(tNode); ok {
			break
		}
	}

	return newMultipartInfoFromTreeNode(m.log, filePath, tNode)
}

// openNewStream creates subtree stream from childStream`s node.
func (m *multipartInfoStream) openNewStream(ctx context.Context) (SubTreeStream, error) {
	node, err := getTreeNodeFromStream(m.childStream)
	if err != nil {
		return nil, err
	}
	if m.rootID.Equal(node.ID) {
		// skip root node
		return m.openNewStream(ctx)
	}
	stream, err := m.treeService.GetSubTreeStream(ctx, m.bktInfo, systemTree, node.ID, maxGetSubTreeDepth)
	if err != nil {
		return nil, err
	}
	return stream, nil
}

func getTreeNodeFromStream(stream SubTreeStream) (*treeNode, error) {
	node, err := stream.Next()
	if err != nil {
		return nil, err
	}
	tNode, err := newTreeNode(node)
	if err != nil {
		return nil, err
	}
	return tNode, nil
}

func (m *multipartInfoStream) checkTreeNode(tNode *treeNode) (string, bool) {
	var ok bool
	var err error

	if tNode.IsSplit() {
		return "", false
	}
	fileName, ok := tNode.FileName()
	if !ok {
		return "", false
	}
	filePath, err := formFilePath(tNode, fileName, m.nodePaths)
	if err != nil {
		filePath = fileName
		m.nodePaths[tNode.ID[0]] = filePath
	}
	filePath = m.headPrefix + filePath
	if !strings.HasPrefix(filePath, m.prefix) {
		return "", false
	}
	if _, ok = tNode.Meta[finishedKV]; ok {
		return "", false
	}
	if id, ok := tNode.Meta[uploadIDKV]; ok {
		if filePath > m.keyMarker || (filePath == m.keyMarker && m.uploadID != "" && id > m.uploadID) {
			return filePath, true
		}
	}

	return "", false
}

func (c *Tree) GetMultipartUploadsByPrefix(ctx context.Context, bktInfo *data.BucketInfo, params data.MultipartStreamParams) (data.MultipartInfoStream, error) {
	stream, rootID, err := c.getSubTreeByPrefixStream(ctx, bktInfo, systemTree, params.Prefix)
	if err != nil {
		if errors.Is(err, tree.ErrNodeNotFound) {
			return nil, nil
		}
		return nil, err
	}

	return &multipartInfoStream{
		log:         c.reqLogger(ctx),
		rootID:      rootID,
		childStream: stream,
		nodePaths:   make(map[uint64]string),
		treeService: c.service,
		bktInfo:     bktInfo,
		uploadID:    params.UploadIDMarker,
		keyMarker:   params.KeyMarker,
		prefix:      params.Prefix,
		headPrefix: strings.TrimRightFunc(params.Prefix, func(r rune) bool {
			return r != '/'
		}),
	}, nil
}

func (c *Tree) GetMultipartUpload(ctx context.Context, bktInfo *data.BucketInfo, objectName, uploadID string) (*data.MultipartInfo, error) {
	path := pathFromName(objectName)
	p := &GetNodesParams{
		BktInfo:  bktInfo,
		TreeID:   systemTree,
		Path:     path,
		AllAttrs: true,
	}

	nodes, err := c.service.GetNodes(ctx, p)
	if err != nil {
		return nil, err
	}

	log := c.reqLogger(ctx)
	for _, node := range nodes {
		info, err := newMultipartInfo(log, node)
		if err != nil {
			continue
		}
		if info.UploadID == uploadID {
			if info.Finished {
				break
			}
			return info, nil
		}
	}

	return nil, tree.ErrNodeNotFound
}

func (c *Tree) AddPart(ctx context.Context, bktInfo *data.BucketInfo, multipartNodeID uint64, info *data.PartInfo) (oldObjIDsToDelete []oid.ID, err error) {
	parts, err := c.service.GetSubTree(ctx, bktInfo, systemTree, []uint64{multipartNodeID}, 2, false)
	if err != nil {
		return nil, err
	}

	meta := map[string]string{
		partNumberKV: strconv.Itoa(info.Number),
		oidKV:        info.OID.EncodeToString(),
		sizeKV:       strconv.FormatUint(info.Size, 10),
		createdKV:    strconv.FormatInt(info.Created.UTC().UnixMilli(), 10),
		etagKV:       info.ETag,
		md5KV:        info.MD5,
	}

	objToDelete := make([]oid.ID, 0, 1)
	partsToDelete := make([]uint64, 0, 1)
	var (
		latestPartID uint64
		maxTimestamp uint64
	)

	multiNodeID := MultiID{multipartNodeID}

	for _, part := range parts {
		if multiNodeID.Equal(part.GetNodeID()) {
			continue
		}

		partInfo, err := newPartInfo(part)
		if err != nil {
			c.reqLogger(ctx).Warn(logs.FailedToParsePartInfo,
				zap.String("key", info.Key),
				zap.String("upload id", info.UploadID),
				zap.Uint64("multipart node id ", multipartNodeID),
				zap.Uint64s("id", part.GetNodeID()),
				zap.Error(err))
			continue
		}
		if partInfo.Number == info.Number {
			nodeID := part.GetNodeID()[0]
			objToDelete = append(objToDelete, partInfo.OID)
			partsToDelete = append(partsToDelete, nodeID)
			timestamp := partInfo.Timestamp
			if timestamp > maxTimestamp {
				maxTimestamp = timestamp
				latestPartID = nodeID
			}
		}
	}

	if len(objToDelete) != 0 {
		if err = c.service.MoveNode(ctx, bktInfo, systemTree, latestPartID, multipartNodeID, meta); err != nil {
			return nil, fmt.Errorf("move part node: %w", err)
		}

		for _, nodeID := range partsToDelete {
			if nodeID == latestPartID {
				continue
			}
			if err = c.service.RemoveNode(ctx, bktInfo, systemTree, nodeID); err != nil {
				c.reqLogger(ctx).Warn(logs.FailedToRemoveOldPartNode,
					zap.String("key", info.Key),
					zap.String("upload id", info.UploadID),
					zap.Uint64("id", nodeID))
			}
		}

		return objToDelete, nil
	}

	if _, err = c.service.AddNode(ctx, bktInfo, systemTree, multipartNodeID, meta); err != nil {
		return nil, err
	}

	return nil, tree.ErrNoNodeToRemove
}

func (c *Tree) GetParts(ctx context.Context, bktInfo *data.BucketInfo, multipartNodeID uint64) ([]*data.PartInfoExtended, error) {
	parts, err := c.service.GetSubTree(ctx, bktInfo, systemTree, []uint64{multipartNodeID}, 2, false)
	if err != nil {
		return nil, err
	}

	result := make([]*data.PartInfoExtended, 0, len(parts))
	for _, part := range parts {
		if len(part.GetNodeID()) != 1 {
			// multipart parts nodeID shouldn't have multiple values
			c.reqLogger(ctx).Warn(logs.UnexpectedMultiNodeIDsInSubTreeMultiParts,
				zap.Uint64("multipart node id ", multipartNodeID),
				zap.Uint64s("node ids", part.GetNodeID()))
			continue
		}
		if part.GetNodeID()[0] == multipartNodeID {
			continue
		}
		partInfo, err := newPartInfo(part)
		if err != nil {
			c.reqLogger(ctx).Warn(logs.FailedToParsePartInfo,
				zap.Uint64("multipart node id ", multipartNodeID),
				zap.Uint64s("node ids", part.GetNodeID()),
				zap.Error(err))
			continue
		}
		result = append(result, partInfo)
	}

	return result, nil
}

func (c *Tree) PutBucketLifecycleConfiguration(ctx context.Context, bktInfo *data.BucketInfo, addr oid.Address) ([]oid.Address, error) {
	multiNode, err := c.getSystemNode(ctx, bktInfo, bucketLifecycleFilename)
	isErrNotFound := errors.Is(err, tree.ErrNodeNotFound)
	if err != nil && !isErrNotFound {
		return nil, fmt.Errorf("couldn't get node: %w", err)
	}

	meta := make(map[string]string)
	meta[FileNameKey] = bucketLifecycleFilename
	meta[oidKV] = addr.Object().EncodeToString()
	meta[cidKV] = addr.Container().EncodeToString()

	if isErrNotFound {
		if _, err = c.service.AddNode(ctx, bktInfo, systemTree, 0, meta); err != nil {
			return nil, err
		}
		return nil, tree.ErrNoNodeToRemove
	}

	latest := multiNode.Latest()
	ind := latest.GetLatestNodeIndex()
	if latest.IsSplit() {
		c.reqLogger(ctx).Error(logs.BucketLifecycleNodeHasMultipleIDs)
	}

	if err = c.service.MoveNode(ctx, bktInfo, systemTree, latest.ID[ind], 0, meta); err != nil {
		return nil, fmt.Errorf("move lifecycle node: %w", err)
	}

	objToDelete := make([]oid.Address, 1, len(multiNode.nodes))
	objToDelete[0], err = getTreeNodeAddress(latest)
	if err != nil {
		return nil, fmt.Errorf("parse object addr of latest lifecycle node in tree: %w", err)
	}

	objToDelete = append(objToDelete, c.cleanOldNodes(ctx, multiNode.Old(), bktInfo)...)

	return objToDelete, nil
}

func (c *Tree) GetBucketLifecycleConfiguration(ctx context.Context, bktInfo *data.BucketInfo) (oid.Address, error) {
	node, err := c.getSystemNode(ctx, bktInfo, bucketLifecycleFilename)
	if err != nil {
		return oid.Address{}, fmt.Errorf("get lifecycle node: %w", err)
	}

	return getTreeNodeAddress(node.Latest())
}

func (c *Tree) DeleteBucketLifecycleConfiguration(ctx context.Context, bktInfo *data.BucketInfo) ([]oid.Address, error) {
	multiNode, err := c.getSystemNode(ctx, bktInfo, bucketLifecycleFilename)
	isErrNotFound := errors.Is(err, tree.ErrNodeNotFound)
	if err != nil && !isErrNotFound {
		return nil, err
	}

	if isErrNotFound {
		return nil, tree.ErrNoNodeToRemove
	}

	objToDelete := c.cleanOldNodes(ctx, multiNode.nodes, bktInfo)
	if len(objToDelete) != len(multiNode.nodes) {
		return nil, fmt.Errorf("failed to clean all old lifecycle nodes")
	}

	return objToDelete, nil
}

func (c *Tree) DeleteMultipartUpload(ctx context.Context, bktInfo *data.BucketInfo, multipartInfo *data.MultipartInfo) error {
	err := c.service.RemoveNode(ctx, bktInfo, systemTree, multipartInfo.ID)
	if err != nil {
		return err
	}

	multipartInfo.Finished = true

	return c.CreateMultipartUpload(ctx, bktInfo, multipartInfo)
}

func (c *Tree) PutLock(ctx context.Context, bktInfo *data.BucketInfo, nodeID uint64, lock *data.LockInfo) error {
	meta := map[string]string{isLockKV: "true"}

	if lock.IsLegalHoldSet() {
		meta[legalHoldOIDKV] = lock.LegalHold().EncodeToString()
	}
	if lock.IsRetentionSet() {
		meta[retentionOIDKV] = lock.Retention().EncodeToString()
		meta[untilDateKV] = lock.UntilDate()
		if lock.IsCompliance() {
			meta[isComplianceKV] = "true"
		}
	}

	if lock.ID() == 0 {
		_, err := c.service.AddNode(ctx, bktInfo, versionTree, nodeID, meta)
		return err
	}

	return c.service.MoveNode(ctx, bktInfo, versionTree, lock.ID(), nodeID, meta)
}

func (c *Tree) GetLock(ctx context.Context, bktInfo *data.BucketInfo, nodeID uint64) (*data.LockInfo, error) {
	lockNode, err := c.getTreeNode(ctx, bktInfo, nodeID, isLockKV)
	if err != nil {
		return nil, err
	}

	return getLock(lockNode)
}

func getLock(lockNode *treeNode) (*data.LockInfo, error) {
	if lockNode == nil {
		return &data.LockInfo{}, nil
	}
	if lockNode.IsSplit() {
		return nil, errors.New("invalid lock node: this is split node")
	}
	lockInfo := data.NewLockInfo(lockNode.ID[0])

	if legalHold, ok := lockNode.Get(legalHoldOIDKV); ok {
		var legalHoldOID oid.ID
		if err := legalHoldOID.DecodeString(legalHold); err != nil {
			return nil, fmt.Errorf("invalid legal hold object id: %w", err)
		}
		lockInfo.SetLegalHold(legalHoldOID)
	}

	if retention, ok := lockNode.Get(retentionOIDKV); ok {
		var retentionOID oid.ID
		if err := retentionOID.DecodeString(retention); err != nil {
			return nil, fmt.Errorf("invalid retention object id: %w", err)
		}
		_, isCompliance := lockNode.Get(isComplianceKV)
		untilDate, _ := lockNode.Get(untilDateKV)
		lockInfo.SetRetention(retentionOID, untilDate, isCompliance)
	}

	return lockInfo, nil
}

func (c *Tree) GetObjectTaggingAndLock(ctx context.Context, bktInfo *data.BucketInfo, objVersion *data.NodeVersion) (map[string]string, *data.LockInfo, error) {
	nodes, err := c.getTreeNodes(ctx, bktInfo, objVersion.ID, isTagKV, isLockKV)
	if err != nil {
		return nil, nil, err
	}

	lockInfo, err := getLock(nodes[isLockKV])
	if err != nil {
		return nil, nil, err
	}

	return getObjectTagging(nodes[isTagKV]), lockInfo, nil
}

func (c *Tree) addVersion(ctx context.Context, bktInfo *data.BucketInfo, treeID string, version *data.NodeVersion) (uint64, error) {
	path := pathFromName(version.FilePath)
	meta := map[string]string{
		oidKV:           version.OID.EncodeToString(),
		FileNameKey:     path[len(path)-1],
		ownerKV:         version.Owner.EncodeToString(),
		createdKV:       strconv.FormatInt(version.Created.UTC().UnixMilli(), 10),
		creationEpochKV: strconv.FormatUint(version.CreationEpoch, 10),
	}

	if version.Size > 0 {
		meta[sizeKV] = strconv.FormatUint(version.Size, 10)
	}
	if len(version.ETag) > 0 {
		meta[etagKV] = version.ETag
	}
	if len(version.MD5) > 0 {
		meta[md5KV] = version.MD5
	}

	if version.IsDeleteMarker {
		meta[isDeleteMarkerKV] = "true"
	}

	if version.IsCombined {
		meta[isCombinedKV] = "true"
	}

	if version.IsUnversioned {
		meta[isUnversionedKV] = "true"

		node, err := c.getUnversioned(ctx, bktInfo, treeID, version.FilePath)
		if err == nil {
			if err = c.service.MoveNode(ctx, bktInfo, treeID, node.ID, node.ParenID, meta); err != nil {
				return 0, err
			}

			return node.ID, c.clearOutdatedVersionInfo(ctx, bktInfo, treeID, node.ID)
		}

		if !errors.Is(err, tree.ErrNodeNotFound) {
			return 0, err
		}
	}

	return c.service.AddNodeByPath(ctx, bktInfo, treeID, path[:len(path)-1], meta)
}

func (c *Tree) clearOutdatedVersionInfo(ctx context.Context, bktInfo *data.BucketInfo, treeID string, nodeID uint64) error {
	taggingNode, err := c.getTreeNode(ctx, bktInfo, nodeID, isTagKV)
	if err != nil {
		return err
	}
	if taggingNode != nil {
		return c.service.RemoveNode(ctx, bktInfo, treeID, taggingNode.ID[0])
	}

	return nil
}

func (c *Tree) getVersions(ctx context.Context, bktInfo *data.BucketInfo, treeID, filepath string, onlyUnversioned bool) ([]*data.NodeVersion, error) {
	keysToReturn := []string{oidKV, isCombinedKV, isUnversionedKV, isDeleteMarkerKV, etagKV, sizeKV, md5KV, creationEpochKV}
	path := pathFromName(filepath)
	p := &GetNodesParams{
		BktInfo:    bktInfo,
		TreeID:     treeID,
		Path:       path,
		Meta:       keysToReturn,
		LatestOnly: false,
		AllAttrs:   false,
	}
	nodes, err := c.service.GetNodes(ctx, p)
	if err != nil {
		if errors.Is(err, tree.ErrNodeNotFound) {
			return nil, nil
		}
		return nil, err
	}

	log := c.reqLogger(ctx)
	result := make([]*data.NodeVersion, 0, len(nodes))
	for _, node := range nodes {
		nodeVersion, err := newNodeVersion(log, filepath, node)
		if err != nil {
			return nil, err
		}

		if onlyUnversioned && !nodeVersion.IsUnversioned {
			continue
		}

		result = append(result, nodeVersion)
	}

	return result, nil
}

func metaFromSettings(settings *data.BucketSettings) map[string]string {
	results := make(map[string]string, 3)

	results[FileNameKey] = settingsFileName
	results[versioningKV] = settings.Versioning
	results[lockConfigurationKV] = encodeLockConfiguration(settings.LockConfiguration)
	results[cannedACLKV] = settings.CannedACL
	if settings.OwnerKey != nil {
		results[ownerKeyKV] = hex.EncodeToString(settings.OwnerKey.Bytes())
	}

	return results
}

func metaFromMultipart(info *data.MultipartInfo, fileName string) map[string]string {
	info.Meta[FileNameKey] = fileName
	info.Meta[uploadIDKV] = info.UploadID
	info.Meta[ownerKV] = info.Owner.EncodeToString()
	info.Meta[createdKV] = strconv.FormatInt(info.Created.UTC().UnixMilli(), 10)
	if info.Finished {
		info.Meta[finishedKV] = strconv.FormatBool(info.Finished)
	}
	info.Meta[creationEpochKV] = strconv.FormatUint(info.CreationEpoch, 10)

	return info.Meta
}

func (c *Tree) getSystemNode(ctx context.Context, bktInfo *data.BucketInfo, name string) (*multiSystemNode, error) {
	p := &GetNodesParams{
		BktInfo:    bktInfo,
		TreeID:     systemTree,
		Path:       []string{name},
		LatestOnly: false,
		AllAttrs:   true,
	}
	nodes, err := c.service.GetNodes(ctx, p)
	if err != nil {
		return nil, err
	}

	nodes = filterMultipartNodes(nodes)

	if len(nodes) == 0 {
		return nil, tree.ErrNodeNotFound
	}
	if len(nodes) != 1 {
		c.reqLogger(ctx).Warn(logs.FoundSeveralSystemNodes, zap.String("name", name))
	}

	return newMultiNode(nodes)
}

func filterMultipartNodes(nodes []NodeResponse) []NodeResponse {
	res := make([]NodeResponse, 0, len(nodes))

LOOP:
	for _, node := range nodes {
		for _, meta := range node.GetMeta() {
			if meta.GetKey() == uploadIDKV {
				continue LOOP
			}
		}

		res = append(res, node)
	}

	return res
}

func (c *Tree) reqLogger(ctx context.Context) *zap.Logger {
	reqLogger := middleware.GetReqLog(ctx)
	if reqLogger != nil {
		return reqLogger
	}
	return c.log
}

func parseLockConfiguration(value string) (*data.ObjectLockConfiguration, error) {
	result := &data.ObjectLockConfiguration{}
	if len(value) == 0 {
		return result, nil
	}

	lockValues := strings.Split(value, ",")
	result.ObjectLockEnabled = lockValues[0]

	if len(lockValues) == 1 {
		return result, nil
	}

	if len(lockValues) != 4 {
		return nil, fmt.Errorf("invalid lock configuration: %s", value)
	}

	var err error
	var days, years int64

	if len(lockValues[1]) > 0 {
		if days, err = strconv.ParseInt(lockValues[1], 10, 64); err != nil {
			return nil, fmt.Errorf("invalid lock configuration: %s", value)
		}
	}

	if len(lockValues[3]) > 0 {
		if years, err = strconv.ParseInt(lockValues[3], 10, 64); err != nil {
			return nil, fmt.Errorf("invalid lock configuration: %s", value)
		}
	}

	result.Rule = &data.ObjectLockRule{
		DefaultRetention: &data.DefaultRetention{
			Days:  days,
			Mode:  lockValues[2],
			Years: years,
		},
	}

	return result, nil
}

func encodeLockConfiguration(conf *data.ObjectLockConfiguration) string {
	if conf == nil {
		return ""
	}

	if conf.Rule == nil || conf.Rule.DefaultRetention == nil {
		return conf.ObjectLockEnabled
	}

	defaults := conf.Rule.DefaultRetention
	return fmt.Sprintf("%s,%d,%s,%d", conf.ObjectLockEnabled, defaults.Days, defaults.Mode, defaults.Years)
}