package handler

import (
	"bytes"
	"crypto/md5"
	"encoding/base64"
	"encoding/json"
	"encoding/xml"
	stderrors "errors"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/auth"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/data"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/errors"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer/encryption"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/middleware"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/creds/accessbox"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/internal/logs"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/pkg/retryer"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/pkg/service/tree"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	"git.frostfs.info/TrueCloudLab/policy-engine/pkg/chain"
	"git.frostfs.info/TrueCloudLab/policy-engine/schema/native"
	"git.frostfs.info/TrueCloudLab/policy-engine/schema/s3"
	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/aws/retry"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"go.uber.org/zap"
)

type postPolicy struct {
	Expiration time.Time          `json:"expiration"`
	Conditions []*policyCondition `json:"conditions"`
	empty      bool
}

func (p *postPolicy) condition(key string) *policyCondition {
	for _, condition := range p.Conditions {
		if condition.Key == key {
			return condition
		}
	}
	return nil
}

func (p *postPolicy) CheckContentLength(size uint64) bool {
	if p.empty {
		return true
	}
	for _, condition := range p.Conditions {
		if condition.Matching == "content-length-range" {
			length := strconv.FormatUint(size, 10)
			return condition.Key <= length && length <= condition.Value
		}
	}
	return true
}

func (p *policyCondition) match(value string) bool {
	switch p.Matching {
	case "eq":
		p.Matched = p.Value == value
	case "starts-with":
		if p.Key == api.ContentType {
			p.Matched = true
			for _, contentType := range strings.Split(value, ",") {
				if !strings.HasPrefix(contentType, p.Value) {
					p.Matched = false
				}
			}
		} else {
			p.Matched = strings.HasPrefix(value, p.Value)
		}
	}
	return p.Matched
}

func (p *postPolicy) CheckField(key string, value string) error {
	if p.empty {
		return nil
	}
	cond := p.condition(key)
	if cond == nil {
		return errors.GetAPIError(errors.ErrPostPolicyConditionInvalidFormat)
	}

	if !cond.match(value) {
		return errors.GetAPIError(errors.ErrPostPolicyConditionInvalidFormat)
	}

	return nil
}

func (p *postPolicy) AllConditionMatched() bool {
	for _, condition := range p.Conditions {
		if !condition.Matched {
			return false
		}
	}
	return true
}

type policyCondition struct {
	Matching string
	Key      string
	Value    string
	Matched  bool
}

var errInvalidCondition = fmt.Errorf("invalid condition")

func (p *policyCondition) UnmarshalJSON(data []byte) error {
	var (
		ok bool
		v  interface{}
	)

	if err := json.Unmarshal(data, &v); err != nil {
		return fmt.Errorf("unmarshal policy condition: %w", err)
	}

	switch v := v.(type) {
	case []interface{}:
		if len(v) != 3 {
			return errInvalidCondition
		}
		if p.Matching, ok = v[0].(string); !ok {
			return errInvalidCondition
		}

		if p.Matching == "content-length-range" {
			min, ok := v[1].(float64)
			max, ok2 := v[2].(float64)
			if !ok || !ok2 {
				return errInvalidCondition
			}
			p.Key = strconv.FormatFloat(min, 'f', 0, 32)
			p.Value = strconv.FormatFloat(max, 'f', 0, 32)
		} else {
			key, ok2 := v[1].(string)
			p.Value, ok = v[2].(string)
			if !ok || !ok2 {
				return errInvalidCondition
			}
			p.Key = strings.ToLower(strings.TrimPrefix(key, "$"))
		}

	case map[string]interface{}:
		p.Matching = "eq"
		for key, val := range v {
			p.Key = strings.ToLower(key)
			if p.Value, ok = val.(string); !ok {
				return errInvalidCondition
			}
		}
	default:
		return fmt.Errorf("unknown condition type")
	}

	return nil
}

// keywords of predefined basic ACL values.
const (
	basicACLPrivate  = "private"
	basicACLReadOnly = "public-read"
	basicACLPublic   = "public-read-write"
)

type createBucketParams struct {
	XMLName            xml.Name `xml:"http://s3.amazonaws.com/doc/2006-03-01/ CreateBucketConfiguration" json:"-"`
	LocationConstraint string
}

func (h *handler) PutObjectHandler(w http.ResponseWriter, r *http.Request) {
	var (
		err             error
		cannedACLStatus = aclHeadersStatus(r)
		ctx             = r.Context()
		reqInfo         = middleware.GetReqInfo(ctx)
	)

	bktInfo, err := h.getBucketAndCheckOwner(r, reqInfo.BucketName)
	if err != nil {
		h.logAndSendError(w, "could not get bucket objInfo", reqInfo, err)
		return
	}

	settings, err := h.obj.GetBucketSettings(ctx, bktInfo)
	if err != nil {
		h.logAndSendError(w, "could not get bucket settings", reqInfo, err)
		return
	}

	if cannedACLStatus == aclStatusYes {
		h.logAndSendError(w, "acl not supported for this bucket", reqInfo, errors.GetAPIError(errors.ErrAccessControlListNotSupported))
		return
	}

	tagSet, err := parseTaggingHeader(r.Header)
	if err != nil {
		h.logAndSendError(w, "could not parse tagging header", reqInfo, err)
		return
	}

	metadata := parseMetadata(r)
	if contentType := r.Header.Get(api.ContentType); len(contentType) > 0 {
		metadata[api.ContentType] = contentType
	}
	if cacheControl := r.Header.Get(api.CacheControl); len(cacheControl) > 0 {
		metadata[api.CacheControl] = cacheControl
	}
	if expires := r.Header.Get(api.Expires); len(expires) > 0 {
		metadata[api.Expires] = expires
	}
	if contentLanguage := r.Header.Get(api.ContentLanguage); len(contentLanguage) > 0 {
		metadata[api.ContentLanguage] = contentLanguage
	}

	encryptionParams, err := formEncryptionParams(r)
	if err != nil {
		h.logAndSendError(w, "invalid sse headers", reqInfo, err)
		return
	}

	body, err := h.getBodyReader(r)
	if err != nil {
		h.logAndSendError(w, "failed to get body reader", reqInfo, err)
		return
	}
	if encodings := r.Header.Get(api.ContentEncoding); len(encodings) > 0 {
		metadata[api.ContentEncoding] = encodings
	}

	size := h.getPutPayloadSize(r)

	params := &layer.PutObjectParams{
		BktInfo:           bktInfo,
		Object:            reqInfo.ObjectName,
		Reader:            body,
		Header:            metadata,
		Encryption:        encryptionParams,
		ContentMD5:        r.Header.Get(api.ContentMD5),
		ContentSHA256Hash: r.Header.Get(api.AmzContentSha256),
	}

	if size > 0 {
		params.Size = &size
	}

	params.CopiesNumbers, err = h.pickCopiesNumbers(metadata, reqInfo.Namespace, bktInfo.LocationConstraint)
	if err != nil {
		h.logAndSendError(w, "invalid copies number", reqInfo, err)
		return
	}

	params.Lock, err = formObjectLock(ctx, bktInfo, settings.LockConfiguration, r.Header)
	if err != nil {
		h.logAndSendError(w, "could not form object lock", reqInfo, err)
		return
	}

	extendedObjInfo, err := h.obj.PutObject(ctx, params)
	if err != nil {
		_, err2 := io.Copy(io.Discard, body)
		err3 := body.Close()
		h.logAndSendError(w, "could not upload object", reqInfo, err, zap.Errors("body close errors", []error{err2, err3}))
		return
	}
	objInfo := extendedObjInfo.ObjectInfo

	if tagSet != nil {
		tagPrm := &data.PutObjectTaggingParams{
			ObjectVersion: &data.ObjectVersion{
				BktInfo:    bktInfo,
				ObjectName: objInfo.Name,
				VersionID:  objInfo.VersionID(),
			},
			TagSet:      tagSet,
			NodeVersion: extendedObjInfo.NodeVersion,
		}
		if err = h.obj.PutObjectTagging(r.Context(), tagPrm); err != nil {
			h.logAndSendError(w, "could not upload object tagging", reqInfo, err)
			return
		}
	}

	if settings.VersioningEnabled() {
		w.Header().Set(api.AmzVersionID, objInfo.VersionID())
	}
	if encryptionParams.Enabled() {
		addSSECHeaders(w.Header(), r.Header)
	}

	w.Header().Set(api.ETag, data.Quote(objInfo.ETag(h.cfg.MD5Enabled())))

	if err = middleware.WriteSuccessResponseHeadersOnly(w); err != nil {
		h.logAndSendError(w, "write response", reqInfo, err)
		return
	}
}

func (h *handler) getBodyReader(r *http.Request) (io.ReadCloser, error) {
	if !api.IsSignedStreamingV4(r) {
		return r.Body, nil
	}

	encodings := r.Header.Values(api.ContentEncoding)
	var chunkedEncoding bool
	resultContentEncoding := make([]string, 0, len(encodings))
	for _, enc := range encodings {
		for _, e := range strings.Split(enc, ",") {
			e = strings.TrimSpace(e)
			if e == api.AwsChunked { // probably we should also check position of this header value
				chunkedEncoding = true
			} else {
				resultContentEncoding = append(resultContentEncoding, e)
			}
		}
	}
	r.Header.Set(api.ContentEncoding, strings.Join(resultContentEncoding, ","))

	if !chunkedEncoding && !h.cfg.BypassContentEncodingInChunks() {
		return nil, fmt.Errorf("%w: request is not chunk encoded, encodings '%s'",
			errors.GetAPIError(errors.ErrInvalidEncodingMethod), strings.Join(encodings, ","))
	}

	decodeContentSize := r.Header.Get(api.AmzDecodedContentLength)
	if len(decodeContentSize) == 0 {
		return nil, errors.GetAPIError(errors.ErrMissingContentLength)
	}

	if _, err := strconv.Atoi(decodeContentSize); err != nil {
		return nil, fmt.Errorf("%w: parse decoded content length: %s", errors.GetAPIError(errors.ErrMissingContentLength), err.Error())
	}

	chunkReader, err := newSignV4ChunkedReader(r)
	if err != nil {
		return nil, fmt.Errorf("initialize chunk reader: %w", err)
	}

	return chunkReader, nil
}

func formEncryptionParams(r *http.Request) (enc encryption.Params, err error) {
	return formEncryptionParamsBase(r, false)
}

func formCopySourceEncryptionParams(r *http.Request) (enc encryption.Params, err error) {
	return formEncryptionParamsBase(r, true)
}

func formEncryptionParamsBase(r *http.Request, isCopySource bool) (enc encryption.Params, err error) {
	var sseCustomerAlgorithm, sseCustomerKey, sseCustomerKeyMD5 string
	if isCopySource {
		sseCustomerAlgorithm = r.Header.Get(api.AmzCopySourceServerSideEncryptionCustomerAlgorithm)
		sseCustomerKey = r.Header.Get(api.AmzCopySourceServerSideEncryptionCustomerKey)
		sseCustomerKeyMD5 = r.Header.Get(api.AmzCopySourceServerSideEncryptionCustomerKeyMD5)
	} else {
		sseCustomerAlgorithm = r.Header.Get(api.AmzServerSideEncryptionCustomerAlgorithm)
		sseCustomerKey = r.Header.Get(api.AmzServerSideEncryptionCustomerKey)
		sseCustomerKeyMD5 = r.Header.Get(api.AmzServerSideEncryptionCustomerKeyMD5)
	}

	if len(sseCustomerAlgorithm) == 0 && len(sseCustomerKey) == 0 && len(sseCustomerKeyMD5) == 0 {
		return
	}

	if r.TLS == nil {
		return enc, errors.GetAPIError(errors.ErrInsecureSSECustomerRequest)
	}

	if len(sseCustomerKey) > 0 && len(sseCustomerAlgorithm) == 0 {
		return enc, errors.GetAPIError(errors.ErrMissingSSECustomerAlgorithm)
	}
	if len(sseCustomerAlgorithm) > 0 && len(sseCustomerKey) == 0 {
		return enc, errors.GetAPIError(errors.ErrMissingSSECustomerKey)
	}

	if sseCustomerAlgorithm != layer.AESEncryptionAlgorithm {
		return enc, errors.GetAPIError(errors.ErrInvalidEncryptionAlgorithm)
	}

	key, err := base64.StdEncoding.DecodeString(sseCustomerKey)
	if err != nil {
		if isCopySource {
			return enc, errors.GetAPIError(errors.ErrInvalidSSECustomerParameters)
		}
		return enc, errors.GetAPIError(errors.ErrInvalidSSECustomerKey)
	}

	if len(key) != layer.AESKeySize {
		if isCopySource {
			return enc, errors.GetAPIError(errors.ErrInvalidSSECustomerParameters)
		}
		return enc, errors.GetAPIError(errors.ErrInvalidSSECustomerKey)
	}

	keyMD5, err := base64.StdEncoding.DecodeString(sseCustomerKeyMD5)
	if err != nil {
		return enc, errors.GetAPIError(errors.ErrSSECustomerKeyMD5Mismatch)
	}

	md5Sum := md5.Sum(key)
	if !bytes.Equal(md5Sum[:], keyMD5) {
		return enc, errors.GetAPIError(errors.ErrSSECustomerKeyMD5Mismatch)
	}

	params, err := encryption.NewParams(key)
	if err == nil {
		enc = *params
	}

	return enc, err
}

func (h *handler) PostObject(w http.ResponseWriter, r *http.Request) {
	var (
		tagSet   map[string]string
		ctx      = r.Context()
		reqInfo  = middleware.GetReqInfo(ctx)
		metadata = make(map[string]string)
	)

	policy, err := checkPostPolicy(r, reqInfo, metadata)
	if err != nil {
		h.logAndSendError(w, "failed check policy", reqInfo, err)
		return
	}

	if tagging := auth.MultipartFormValue(r, "tagging"); tagging != "" {
		buffer := bytes.NewBufferString(tagging)
		tags := new(data.Tagging)
		if err = h.cfg.NewXMLDecoder(buffer).Decode(tags); err != nil {
			h.logAndSendError(w, "could not decode tag set", reqInfo,
				fmt.Errorf("%w: %s", errors.GetAPIError(errors.ErrMalformedXML), err.Error()))
			return
		}
		tagSet, err = h.readTagSet(tags)
		if err != nil {
			h.logAndSendError(w, "could not read tag set", reqInfo, err)
			return
		}
	}

	bktInfo, err := h.getBucketAndCheckOwner(r, reqInfo.BucketName)
	if err != nil {
		h.logAndSendError(w, "could not get bucket objInfo", reqInfo, err)
		return
	}

	settings, err := h.obj.GetBucketSettings(ctx, bktInfo)
	if err != nil {
		h.logAndSendError(w, "could not get bucket settings", reqInfo, err)
		return
	}

	if acl := auth.MultipartFormValue(r, "acl"); acl != "" && acl != basicACLPrivate {
		h.logAndSendError(w, "acl not supported for this bucket", reqInfo, errors.GetAPIError(errors.ErrAccessControlListNotSupported))
		return
	}

	var contentReader io.Reader
	var size uint64
	if content, ok := r.MultipartForm.Value["file"]; ok {
		contentReader = bytes.NewBufferString(content[0])
		size = uint64(len(content[0]))
	} else {
		file, head, err := r.FormFile("file")
		if err != nil {
			h.logAndSendError(w, "could get uploading file", reqInfo, err)
			return
		}
		contentReader = file
		size = uint64(head.Size)
		reqInfo.ObjectName = strings.ReplaceAll(reqInfo.ObjectName, "${filename}", head.Filename)
	}
	if !policy.CheckContentLength(size) {
		h.logAndSendError(w, "invalid content-length", reqInfo, errors.GetAPIError(errors.ErrInvalidArgument))
		return
	}

	params := &layer.PutObjectParams{
		BktInfo: bktInfo,
		Object:  reqInfo.ObjectName,
		Reader:  contentReader,
		Size:    &size,
		Header:  metadata,
	}

	extendedObjInfo, err := h.obj.PutObject(ctx, params)
	if err != nil {
		h.logAndSendError(w, "could not upload object", reqInfo, err)
		return
	}
	objInfo := extendedObjInfo.ObjectInfo

	if tagSet != nil {
		tagPrm := &data.PutObjectTaggingParams{
			ObjectVersion: &data.ObjectVersion{
				BktInfo:    bktInfo,
				ObjectName: objInfo.Name,
				VersionID:  objInfo.VersionID(),
			},
			NodeVersion: extendedObjInfo.NodeVersion,
		}

		if err = h.obj.PutObjectTagging(ctx, tagPrm); err != nil {
			h.logAndSendError(w, "could not upload object tagging", reqInfo, err)
			return
		}
	}

	if settings.VersioningEnabled() {
		w.Header().Set(api.AmzVersionID, objInfo.VersionID())
	}

	if redirectURL := auth.MultipartFormValue(r, "success_action_redirect"); redirectURL != "" {
		http.Redirect(w, r, redirectURL, http.StatusTemporaryRedirect)
		return
	}
	status := http.StatusNoContent
	if statusStr := auth.MultipartFormValue(r, "success_action_status"); statusStr != "" {
		switch statusStr {
		case "200":
			status = http.StatusOK
		case "201":
			status = http.StatusCreated
			resp := &PostResponse{
				Bucket: objInfo.Bucket,
				Key:    objInfo.Name,
				ETag:   data.Quote(objInfo.ETag(h.cfg.MD5Enabled())),
			}
			w.WriteHeader(status)
			respData, err := middleware.EncodeResponse(resp)
			if err != nil {
				h.logAndSendError(w, "encode response", reqInfo, err)
			}
			if _, err = w.Write(respData); err != nil {
				h.logAndSendError(w, "something went wrong", reqInfo, err)
			}
			return
		}
	}

	w.Header().Set(api.ETag, data.Quote(objInfo.ETag(h.cfg.MD5Enabled())))
	w.WriteHeader(status)
}

func checkPostPolicy(r *http.Request, reqInfo *middleware.ReqInfo, metadata map[string]string) (*postPolicy, error) {
	policy := &postPolicy{empty: true}
	if policyStr := auth.MultipartFormValue(r, "policy"); policyStr != "" {
		policyData, err := base64.StdEncoding.DecodeString(policyStr)
		if err != nil {
			return nil, fmt.Errorf("could not decode policy: %w", err)
		}
		if err = json.Unmarshal(policyData, policy); err != nil {
			return nil, fmt.Errorf("could not unmarshal policy: %w", err)
		}
		if policy.Expiration.Before(time.Now()) {
			return nil, fmt.Errorf("policy is expired: %w", errors.GetAPIError(errors.ErrInvalidArgument))
		}
		policy.empty = false
	}

	if r.MultipartForm == nil {
		return nil, stderrors.New("empty multipart form")
	}

	for key, v := range r.MultipartForm.Value {
		if key == "file" || key == "policy" || key == "x-amz-signature" || strings.HasPrefix(key, "x-ignore-") {
			continue
		}

		if len(v) != 1 {
			return nil, fmt.Errorf("empty multipart value for key '%s'", key)
		}

		value := v[0]

		if err := policy.CheckField(key, value); err != nil {
			return nil, fmt.Errorf("'%s' form field doesn't match the policy: %w", key, err)
		}

		prefix := strings.ToLower(api.MetadataPrefix)
		if strings.HasPrefix(key, prefix) {
			metadata[strings.TrimPrefix(key, prefix)] = value
		}

		if key == "content-type" {
			metadata[api.ContentType] = value
		}

		if key == "key" {
			reqInfo.ObjectName = value
		}
	}

	for _, cond := range policy.Conditions {
		if cond.Key == "bucket" {
			if !cond.match(reqInfo.BucketName) {
				return nil, errors.GetAPIError(errors.ErrPostPolicyConditionInvalidFormat)
			}
		}
	}

	return policy, nil
}

type aclStatus int

const (
	// aclStatusNo means no acl headers at all.
	aclStatusNo aclStatus = iota
	// aclStatusYesAPECompatible means that only X-Amz-Acl present and equals to private.
	aclStatusYesAPECompatible
	// aclStatusYes means any other acl headers configuration.
	aclStatusYes
)

func aclHeadersStatus(r *http.Request) aclStatus {
	if r.Header.Get(api.AmzGrantRead) != "" ||
		r.Header.Get(api.AmzGrantFullControl) != "" ||
		r.Header.Get(api.AmzGrantWrite) != "" {
		return aclStatusYes
	}

	cannedACL := r.Header.Get(api.AmzACL)
	if cannedACL != "" {
		if cannedACL == basicACLPrivate {
			return aclStatusYesAPECompatible
		}
		return aclStatusYes
	}

	return aclStatusNo
}

func parseTaggingHeader(header http.Header) (map[string]string, error) {
	var tagSet map[string]string
	if tagging := header.Get(api.AmzTagging); len(tagging) > 0 {
		queries, err := url.ParseQuery(tagging)
		if err != nil {
			return nil, errors.GetAPIError(errors.ErrInvalidArgument)
		}
		if len(queries) > maxTags {
			return nil, errors.GetAPIError(errors.ErrInvalidTagsSizeExceed)
		}
		tagSet = make(map[string]string, len(queries))
		for k, v := range queries {
			tag := data.Tag{Key: k, Value: v[0]}
			if err = checkTag(tag); err != nil {
				return nil, err
			}
			tagSet[tag.Key] = tag.Value
		}
	}
	return tagSet, nil
}

func parseMetadata(r *http.Request) map[string]string {
	res := make(map[string]string)
	for k, v := range r.Header {
		if strings.HasPrefix(k, api.MetadataPrefix) {
			key := strings.ToLower(strings.TrimPrefix(k, api.MetadataPrefix))
			res[key] = v[0]
		}
	}
	return res
}

func parseCannedACL(header http.Header) (string, error) {
	acl := header.Get(api.AmzACL)
	if len(acl) == 0 {
		return basicACLPrivate, nil
	}

	if acl == basicACLPrivate || acl == basicACLPublic || acl == basicACLReadOnly {
		return acl, nil
	}

	return "", fmt.Errorf("unknown acl: %s", acl)
}

func (h *handler) CreateBucketHandler(w http.ResponseWriter, r *http.Request) {
	h.createBucketHandlerPolicy(w, r)
}

func (h *handler) parseCommonCreateBucketParams(reqInfo *middleware.ReqInfo, boxData *accessbox.Box, r *http.Request) (*keys.PublicKey, *layer.CreateBucketParams, error) {
	p := &layer.CreateBucketParams{
		Name:                     reqInfo.BucketName,
		Namespace:                reqInfo.Namespace,
		SessionContainerCreation: boxData.Gate.SessionTokenForPut(),
	}

	if p.SessionContainerCreation == nil {
		return nil, nil, fmt.Errorf("%w: couldn't find session token for put", errors.GetAPIError(errors.ErrAccessDenied))
	}

	if err := checkBucketName(reqInfo.BucketName); err != nil {
		return nil, nil, fmt.Errorf("invalid bucket name: %w", err)
	}

	key, err := getTokenIssuerKey(boxData)
	if err != nil {
		return nil, nil, fmt.Errorf("couldn't get bearer token signature key: %w", err)
	}

	createParams, err := h.parseLocationConstraint(r)
	if err != nil {
		return nil, nil, fmt.Errorf("could not parse location contraint: %w", err)
	}

	if err = h.setPlacementPolicy(p, reqInfo.Namespace, createParams.LocationConstraint, boxData.Policies); err != nil {
		return nil, nil, fmt.Errorf("couldn't set placement policy: %w", err)
	}

	p.ObjectLockEnabled = isLockEnabled(h.reqLogger(r.Context()), r.Header)

	return key, p, nil
}

func (h *handler) createBucketHandlerPolicy(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	reqInfo := middleware.GetReqInfo(ctx)

	boxData, err := middleware.GetBoxData(ctx)
	if err != nil {
		h.logAndSendError(w, "get access box from request", reqInfo, err)
		return
	}

	key, p, err := h.parseCommonCreateBucketParams(reqInfo, boxData, r)
	if err != nil {
		h.logAndSendError(w, "parse create bucket params", reqInfo, err)
		return
	}

	cannedACL, err := parseCannedACL(r.Header)
	if err != nil {
		h.logAndSendError(w, "could not parse canned ACL", reqInfo, err)
		return
	}

	bktInfo, err := h.obj.CreateBucket(ctx, p)
	if err != nil {
		h.logAndSendError(w, "could not create bucket", reqInfo, err)
		return
	}
	h.reqLogger(ctx).Info(logs.BucketIsCreated, zap.Stringer("container_id", bktInfo.CID))

	chains := bucketCannedACLToAPERules(cannedACL, reqInfo, bktInfo.CID)
	if err = h.ape.SaveACLChains(bktInfo.CID.EncodeToString(), chains); err != nil {
		h.logAndSendError(w, "failed to add morph rule chain", reqInfo, err)
		return
	}

	sp := &layer.PutSettingsParams{
		BktInfo: bktInfo,
		Settings: &data.BucketSettings{
			CannedACL:  cannedACL,
			OwnerKey:   key,
			Versioning: data.VersioningUnversioned,
		},
	}

	if p.ObjectLockEnabled {
		sp.Settings.Versioning = data.VersioningEnabled
	}

	err = retryer.MakeWithRetry(ctx, func() error {
		return h.obj.PutBucketSettings(ctx, sp)
	}, h.putBucketSettingsRetryer())
	if err != nil {
		h.logAndSendError(w, "couldn't save bucket settings", reqInfo, err,
			zap.String("container_id", bktInfo.CID.EncodeToString()))
		return
	}

	if err = middleware.WriteSuccessResponseHeadersOnly(w); err != nil {
		h.logAndSendError(w, "write response", reqInfo, err)
		return
	}
}

func (h *handler) putBucketSettingsRetryer() aws.RetryerV2 {
	return retry.NewStandard(func(options *retry.StandardOptions) {
		options.MaxAttempts = h.cfg.RetryMaxAttempts()
		options.MaxBackoff = h.cfg.RetryMaxBackoff()
		if h.cfg.RetryStrategy() == RetryStrategyExponential {
			options.Backoff = retry.NewExponentialJitterBackoff(options.MaxBackoff)
		} else {
			options.Backoff = retry.BackoffDelayerFunc(func(int, error) (time.Duration, error) {
				return options.MaxBackoff, nil
			})
		}

		options.Retryables = []retry.IsErrorRetryable{retry.IsErrorRetryableFunc(func(err error) aws.Ternary {
			if stderrors.Is(err, tree.ErrNodeAccessDenied) {
				return aws.TrueTernary
			}
			return aws.FalseTernary
		})}
	})
}

const s3ActionPrefix = "s3:"

var (
	// https://docs.aws.amazon.com/AmazonS3/latest/userguide/acl-overview.html

	writeACLBucketS3Actions = []string{
		s3ActionPrefix + middleware.PutObjectOperation,
		s3ActionPrefix + middleware.PostObjectOperation,
		s3ActionPrefix + middleware.CopyObjectOperation,
		s3ActionPrefix + middleware.UploadPartOperation,
		s3ActionPrefix + middleware.UploadPartCopyOperation,
		s3ActionPrefix + middleware.CreateMultipartUploadOperation,
		s3ActionPrefix + middleware.CompleteMultipartUploadOperation,
	}

	readACLBucketS3Actions = []string{
		s3ActionPrefix + middleware.HeadBucketOperation,
		s3ActionPrefix + middleware.GetBucketLocationOperation,
		s3ActionPrefix + middleware.ListObjectsV1Operation,
		s3ActionPrefix + middleware.ListObjectsV2Operation,
		s3ActionPrefix + middleware.ListBucketObjectVersionsOperation,
		s3ActionPrefix + middleware.ListMultipartUploadsOperation,
	}

	writeACLBucketNativeActions = []string{
		native.MethodPutObject,
	}

	readACLBucketNativeActions = []string{
		native.MethodGetContainer,
		native.MethodGetObject,
		native.MethodHeadObject,
		native.MethodSearchObject,
		native.MethodRangeObject,
		native.MethodHashObject,
	}
)

func bucketCannedACLToAPERules(cannedACL string, reqInfo *middleware.ReqInfo, cnrID cid.ID) []*chain.Chain {
	cnrIDStr := cnrID.EncodeToString()

	chains := []*chain.Chain{
		{
			ID:    getBucketCannedChainID(chain.S3, cnrID),
			Rules: []chain.Rule{},
		},
		{
			ID:    getBucketCannedChainID(chain.Ingress, cnrID),
			Rules: []chain.Rule{},
		},
	}

	switch cannedACL {
	case basicACLPrivate:
	case basicACLReadOnly:
		chains[0].Rules = append(chains[0].Rules, chain.Rule{
			Status:  chain.Allow,
			Actions: chain.Actions{Names: readACLBucketS3Actions},
			Resources: chain.Resources{Names: []string{
				fmt.Sprintf(s3.ResourceFormatS3Bucket, reqInfo.BucketName),
				fmt.Sprintf(s3.ResourceFormatS3BucketObjects, reqInfo.BucketName),
			}},
		})

		chains[1].Rules = append(chains[1].Rules, chain.Rule{
			Status:  chain.Allow,
			Actions: chain.Actions{Names: readACLBucketNativeActions},
			Resources: chain.Resources{Names: []string{
				fmt.Sprintf(native.ResourceFormatNamespaceContainer, reqInfo.Namespace, cnrIDStr),
				fmt.Sprintf(native.ResourceFormatNamespaceContainerObjects, reqInfo.Namespace, cnrIDStr),
			}},
		})
	case basicACLPublic:
		chains[0].Rules = append(chains[0].Rules, chain.Rule{
			Status:  chain.Allow,
			Actions: chain.Actions{Names: append(readACLBucketS3Actions, writeACLBucketS3Actions...)},
			Resources: chain.Resources{Names: []string{
				fmt.Sprintf(s3.ResourceFormatS3Bucket, reqInfo.BucketName),
				fmt.Sprintf(s3.ResourceFormatS3BucketObjects, reqInfo.BucketName),
			}},
		})

		chains[1].Rules = append(chains[1].Rules, chain.Rule{
			Status:  chain.Allow,
			Actions: chain.Actions{Names: append(readACLBucketNativeActions, writeACLBucketNativeActions...)},
			Resources: chain.Resources{Names: []string{
				fmt.Sprintf(native.ResourceFormatNamespaceContainer, reqInfo.Namespace, cnrIDStr),
				fmt.Sprintf(native.ResourceFormatNamespaceContainerObjects, reqInfo.Namespace, cnrIDStr),
			}},
		})
	default:
		panic("unknown canned acl") // this should never happen
	}

	return chains
}

func getBucketCannedChainID(prefix chain.Name, cnrID cid.ID) chain.ID {
	return chain.ID(string(prefix) + ":bktCanned" + string(cnrID[:]))
}

func (h handler) setPlacementPolicy(prm *layer.CreateBucketParams, namespace, locationConstraint string, userPolicies []*accessbox.ContainerPolicy) error {
	prm.Policy = h.cfg.DefaultPlacementPolicy(namespace)
	prm.LocationConstraint = locationConstraint

	if locationConstraint == "" {
		return nil
	}

	for _, placementPolicy := range userPolicies {
		if placementPolicy.LocationConstraint == locationConstraint {
			prm.Policy = placementPolicy.Policy
			return nil
		}
	}

	if policy, ok := h.cfg.PlacementPolicy(namespace, locationConstraint); ok {
		prm.Policy = policy
		return nil
	}

	return errors.GetAPIError(errors.ErrInvalidLocationConstraint)
}

func isLockEnabled(log *zap.Logger, header http.Header) bool {
	lockEnabledStr := header.Get(api.AmzBucketObjectLockEnabled)
	if len(lockEnabledStr) == 0 {
		return false
	}

	lockEnabled, err := strconv.ParseBool(lockEnabledStr)
	if err != nil {
		log.Warn(logs.InvalidBucketObjectLockEnabledHeader, zap.String("header", lockEnabledStr), zap.Error(err))
	}

	return lockEnabled
}

func checkBucketName(bucketName string) error {
	if len(bucketName) < 3 || len(bucketName) > 63 {
		return errors.GetAPIError(errors.ErrInvalidBucketName)
	}

	if strings.HasPrefix(bucketName, "xn--") || strings.HasSuffix(bucketName, "-s3alias") {
		return errors.GetAPIError(errors.ErrInvalidBucketName)
	}
	if net.ParseIP(bucketName) != nil {
		return errors.GetAPIError(errors.ErrInvalidBucketName)
	}

	labels := strings.Split(bucketName, ".")
	for _, label := range labels {
		if len(label) == 0 {
			return errors.GetAPIError(errors.ErrInvalidBucketName)
		}
		for i, r := range label {
			if !isAlphaNum(r) && r != '-' {
				return errors.GetAPIError(errors.ErrInvalidBucketName)
			}
			if (i == 0 || i == len(label)-1) && r == '-' {
				return errors.GetAPIError(errors.ErrInvalidBucketName)
			}
		}
	}

	return nil
}

func isAlphaNum(char int32) bool {
	return 'a' <= char && char <= 'z' || '0' <= char && char <= '9'
}

func (h *handler) parseLocationConstraint(r *http.Request) (*createBucketParams, error) {
	if r.ContentLength == 0 {
		return new(createBucketParams), nil
	}

	params := new(createBucketParams)
	if err := h.cfg.NewXMLDecoder(r.Body).Decode(params); err != nil {
		return nil, fmt.Errorf("%w: %s", errors.GetAPIError(errors.ErrMalformedXML), err.Error())
	}
	return params, nil
}