package layer

import (
	"context"
	"errors"
	"fmt"
	"io"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/nspcc-dev/neofs-s3-gw/api"
	"github.com/nspcc-dev/neofs-s3-gw/api/cache"
	"github.com/nspcc-dev/neofs-s3-gw/api/data"
	apiErrors "github.com/nspcc-dev/neofs-s3-gw/api/errors"
	cid "github.com/nspcc-dev/neofs-sdk-go/container/id"
	"github.com/nspcc-dev/neofs-sdk-go/object"
	"github.com/nspcc-dev/neofs-sdk-go/object/address"
	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
	"github.com/nspcc-dev/neofs-sdk-go/owner"
	"go.uber.org/zap"
)

type (
	findParams struct {
		filters []filter
		cid     *cid.ID
		prefix  string
	}

	filter struct {
		attr string
		val  string
	}

	getParams struct {
		w io.Writer

		// payload range
		off, ln uint64

		cid *cid.ID
		oid *oid.ID
	}

	// ListObjectsParamsCommon contains common parameters for ListObjectsV1 and ListObjectsV2.
	ListObjectsParamsCommon struct {
		Bucket    string
		Delimiter string
		Encode    string
		MaxKeys   int
		Prefix    string
	}

	// ListObjectsParamsV1 contains params for ListObjectsV1.
	ListObjectsParamsV1 struct {
		ListObjectsParamsCommon
		Marker string
	}

	// ListObjectsParamsV2 contains params for ListObjectsV2.
	ListObjectsParamsV2 struct {
		ListObjectsParamsCommon
		ContinuationToken string
		StartAfter        string
		FetchOwner        bool
	}

	allObjectParams struct {
		Bucket    *data.BucketInfo
		Delimiter string
		Prefix    string
	}
)

func (n *layer) objectSearchByName(ctx context.Context, cid *cid.ID, filename string) ([]oid.ID, error) {
	f := &findParams{
		filters: []filter{{attr: object.AttributeFileName, val: filename}},
		cid:     cid,
		prefix:  "",
	}
	return n.objectSearch(ctx, f)
}

// objectSearch returns all available objects by search params.
func (n *layer) objectSearch(ctx context.Context, p *findParams) ([]oid.ID, error) {
	var filters object.SearchFilters
	filters.AddRootFilter()

	for _, filter := range p.filters {
		filters.AddFilter(filter.attr, filter.val, object.MatchStringEqual)
	}

	if p.prefix != "" {
		filters.AddFilter(object.AttributeFileName, p.prefix, object.MatchCommonPrefix)
	}

	res, err := n.pool.SearchObjects(ctx, *p.cid, filters, n.CallOptions(ctx)...)
	if err != nil {
		return nil, fmt.Errorf("init searching using client: %w", err)
	}

	defer res.Close()

	var num, read int
	buf := make([]oid.ID, 10)

	for {
		num, err = res.Read(buf[read:])
		if num > 0 {
			read += num
			buf = append(buf, oid.ID{})
			buf = buf[:cap(buf)]
		}

		if err != nil {
			if errors.Is(err, io.EOF) {
				break
			}

			return nil, n.transformNeofsError(ctx, err)
		}
	}

	return buf[:read], nil
}

func newAddress(cid *cid.ID, oid *oid.ID) *address.Address {
	addr := address.NewAddress()
	addr.SetContainerID(cid)
	addr.SetObjectID(oid)
	return addr
}

// objectHead returns all object's headers.
func (n *layer) objectHead(ctx context.Context, idCnr *cid.ID, idObj *oid.ID) (*object.Object, error) {
	var addr address.Address

	addr.SetContainerID(idCnr)
	addr.SetObjectID(idObj)

	obj, err := n.pool.HeadObject(ctx, addr, n.CallOptions(ctx)...)
	return obj, n.transformNeofsError(ctx, err)
}

// writes payload part of the NeoFS object to the provided io.Writer.
// Zero range corresponds to full payload (panics if only offset is set).
func (n *layer) objectWritePayload(ctx context.Context, p getParams) error {
	// form object address
	var a address.Address

	a.SetContainerID(p.cid)
	a.SetObjectID(p.oid)

	fmt.Println("objectWritePayload", p.cid, p.oid)

	// init payload reader
	var r io.ReadCloser

	if p.ln+p.off == 0 {
		res, err := n.pool.GetObject(ctx, a, n.CallOptions(ctx)...)
		if err != nil {
			return n.transformNeofsError(ctx, fmt.Errorf("get object using client: %w", err))
		}

		p.ln = res.Header.PayloadSize()
		r = res.Payload
	} else {
		res, err := n.pool.ObjectRange(ctx, a, p.off, p.ln, n.CallOptions(ctx)...)
		if err != nil {
			return n.transformNeofsError(ctx, fmt.Errorf("range object payload using client: %w", err))
		}

		r = res
	}

	defer r.Close()

	if p.ln > 0 {
		if p.ln > 4096 { // configure?
			p.ln = 4096
		}

		// alloc buffer for copying
		buf := make([]byte, p.ln) // sync-pool it?

		// copy full payload
		_, err := io.CopyBuffer(p.w, r, buf)
		if err != nil {
			return n.transformNeofsError(ctx, fmt.Errorf("copy payload range: %w", err))
		}
	}

	return nil
}

// objectGet returns an object with payload in the object.
func (n *layer) objectGet(ctx context.Context, addr *address.Address) (*object.Object, error) {
	res, err := n.pool.GetObject(ctx, *addr, n.CallOptions(ctx)...)
	if err != nil {
		return nil, n.transformNeofsError(ctx, err)
	}

	defer res.Payload.Close()

	payload, err := io.ReadAll(res.Payload)
	if err != nil {
		return nil, fmt.Errorf("read payload: %w", err)
	}

	object.NewRawFrom(&res.Header).SetPayload(payload)

	return &res.Header, nil
}

// objectPut into NeoFS, took payload from io.Reader.
func (n *layer) objectPut(ctx context.Context, bkt *data.BucketInfo, p *PutObjectParams) (*data.ObjectInfo, error) {
	own := n.Owner(ctx)

	versioningEnabled := n.isVersioningEnabled(ctx, bkt)
	versions, err := n.headVersions(ctx, bkt, p.Object)
	if err != nil && !apiErrors.IsS3Error(err, apiErrors.ErrNoSuchKey) {
		return nil, err
	}
	idsToDeleteArr := updateCRDT2PSetHeaders(p.Header, versions, versioningEnabled)

	r := p.Reader
	if r != nil {
		if len(p.Header[api.ContentType]) == 0 {
			d := newDetector(r)
			if contentType, err := d.Detect(); err == nil {
				p.Header[api.ContentType] = contentType
			}
			r = d.MultiReader()
		}
	}
	rawObject := formRawObject(p, bkt.CID, own, p.Object)

	id, err := n.pool.PutObject(ctx, *rawObject.Object(), r, n.CallOptions(ctx)...)
	if err != nil {
		return nil, n.transformNeofsError(ctx, err)
	}

	if p.Header[VersionsDeleteMarkAttr] == DelMarkFullObject {
		if last := versions.getLast(); last != nil {
			n.objCache.Delete(last.Address())
		}
	}

	meta, err := n.objectHead(ctx, bkt.CID, id)
	if err != nil {
		return nil, err
	}

	if err = n.objCache.Put(*meta); err != nil {
		n.log.Error("couldn't cache an object", zap.Error(err))
	}

	n.listsCache.CleanCacheEntriesContainingObject(p.Object, bkt.CID)

	for _, id := range idsToDeleteArr {
		if err = n.objectDelete(ctx, bkt.CID, id); err != nil {
			n.log.Warn("couldn't delete object",
				zap.Stringer("version id", id),
				zap.Error(err))
		}
		if !versioningEnabled {
			if objVersion := versions.getVersion(id); objVersion != nil {
				if err = n.DeleteObjectTagging(ctx, objVersion); err != nil {
					n.log.Warn("couldn't delete object tagging",
						zap.Stringer("version id", id),
						zap.Error(err))
				}
			}
		}
	}

	return &data.ObjectInfo{
		ID:  id,
		CID: bkt.CID,

		Owner:         own,
		Bucket:        p.Bucket,
		Name:          p.Object,
		Size:          p.Size,
		Created:       time.Now(),
		CreationEpoch: meta.CreationEpoch(),
		Headers:       p.Header,
		ContentType:   p.Header[api.ContentType],
		HashSum:       meta.PayloadChecksum().String(),
	}, nil
}

func formRawObject(p *PutObjectParams, bktID *cid.ID, own *owner.ID, obj string) *object.RawObject {
	attributes := make([]*object.Attribute, 0, len(p.Header)+2)
	filename := object.NewAttribute()
	filename.SetKey(object.AttributeFileName)
	filename.SetValue(obj)

	createdAt := object.NewAttribute()
	createdAt.SetKey(object.AttributeTimestamp)
	createdAt.SetValue(strconv.FormatInt(time.Now().UTC().Unix(), 10))

	attributes = append(attributes, filename, createdAt)

	for k, v := range p.Header {
		ua := object.NewAttribute()
		ua.SetKey(k)
		ua.SetValue(v)

		attributes = append(attributes, ua)
	}

	raw := object.NewRaw()
	raw.SetOwnerID(own)
	raw.SetContainerID(bktID)
	raw.SetAttributes(attributes...)
	raw.SetPayloadSize(uint64(p.Size))

	return raw
}

func updateCRDT2PSetHeaders(header map[string]string, versions *objectVersions, versioningEnabled bool) []*oid.ID {
	if !versioningEnabled {
		header[versionsUnversionedAttr] = "true"
	}

	var idsToDeleteArr []*oid.ID
	if versions.isEmpty() {
		return idsToDeleteArr
	}

	if !versions.isAddListEmpty() {
		header[versionsAddAttr] = versions.getAddHeader()
	}

	if versioningEnabled {
		versionsDeletedStr := versions.getDelHeader()
		// header[versionsDelAttr] can be not empty when deleting specific version
		if delAttr := header[versionsDelAttr]; len(delAttr) != 0 {
			if len(versionsDeletedStr) != 0 {
				header[versionsDelAttr] = versionsDeletedStr + "," + delAttr
			} else {
				header[versionsDelAttr] = delAttr
			}
		} else if len(versionsDeletedStr) != 0 {
			header[versionsDelAttr] = versionsDeletedStr
		}
	} else {
		versionsDeletedStr := versions.getDelHeader()

		var additionalDel string
		for i, del := range versions.unversioned() {
			if i != 0 {
				additionalDel += ","
			}
			additionalDel += del.Version()
			idsToDeleteArr = append(idsToDeleteArr, del.ID)
		}

		if len(additionalDel) != 0 {
			if len(versionsDeletedStr) != 0 {
				versionsDeletedStr += ","
			}
			versionsDeletedStr += additionalDel
		}

		if len(versionsDeletedStr) != 0 {
			header[versionsDelAttr] = versionsDeletedStr
		}
	}

	return idsToDeleteArr
}

func (n *layer) headLastVersionIfNotDeleted(ctx context.Context, bkt *data.BucketInfo, objectName string) (*data.ObjectInfo, error) {
	if addr := n.namesCache.Get(bkt.Name + "/" + objectName); addr != nil {
		if headInfo := n.objCache.Get(addr); headInfo != nil {
			return objInfoFromMeta(bkt, headInfo), nil
		}
	}

	versions, err := n.headVersions(ctx, bkt, objectName)
	if err != nil {
		return nil, err
	}

	lastVersion := versions.getLast()
	if lastVersion == nil {
		return nil, apiErrors.GetAPIError(apiErrors.ErrNoSuchKey)
	}

	if err = n.namesCache.Put(lastVersion.NiceName(), lastVersion.Address()); err != nil {
		n.log.Warn("couldn't put obj address to head cache",
			zap.String("obj nice name", lastVersion.NiceName()),
			zap.Error(err))
	}

	return lastVersion, nil
}

func (n *layer) headVersions(ctx context.Context, bkt *data.BucketInfo, objectName string) (*objectVersions, error) {
	ids, err := n.objectSearchByName(ctx, bkt.CID, objectName)
	if err != nil {
		return nil, err
	}

	versions := newObjectVersions(objectName)
	if len(ids) == 0 {
		return versions, apiErrors.GetAPIError(apiErrors.ErrNoSuchKey)
	}

	for i := range ids {
		meta, err := n.objectHead(ctx, bkt.CID, &ids[i])
		if err != nil {
			n.log.Warn("couldn't head object",
				zap.Stringer("object id", &ids[i]),
				zap.Stringer("bucket id", bkt.CID),
				zap.Error(err))
			continue
		}
		if err = n.objCache.Put(*meta); err != nil {
			n.log.Warn("couldn't put meta to objects cache",
				zap.Stringer("object id", &ids[i]),
				zap.Stringer("bucket id", bkt.CID),
				zap.Error(err))
		}

		if oi := objInfoFromMeta(bkt, meta); oi != nil {
			if isSystem(oi) {
				continue
			}
			versions.appendVersion(oi)
		}
	}

	return versions, nil
}

func (n *layer) headVersion(ctx context.Context, bkt *data.BucketInfo, p *HeadObjectParams) (*data.ObjectInfo, error) {
	if p.VersionID == unversionedObjectVersionID {
		versions, err := n.headVersions(ctx, bkt, p.Object)
		if err != nil {
			return nil, err
		}

		objInfo := versions.getLast(FromUnversioned())
		if objInfo == nil {
			return nil, apiErrors.GetAPIError(apiErrors.ErrNoSuchVersion)
		}
		return objInfo, nil
	}

	id := oid.NewID()
	if err := id.Parse(p.VersionID); err != nil {
		return nil, apiErrors.GetAPIError(apiErrors.ErrInvalidVersion)
	}

	if headInfo := n.objCache.Get(newAddress(bkt.CID, id)); headInfo != nil {
		return objInfoFromMeta(bkt, headInfo), nil
	}

	meta, err := n.objectHead(ctx, bkt.CID, id)
	if err != nil {
		if strings.Contains(err.Error(), "not found") {
			return nil, apiErrors.GetAPIError(apiErrors.ErrNoSuchVersion)
		}
		return nil, err
	}

	objInfo := objInfoFromMeta(bkt, meta)
	if err = n.objCache.Put(*meta); err != nil {
		n.log.Warn("couldn't put obj to object cache",
			zap.String("bucket name", objInfo.Bucket),
			zap.Stringer("bucket cid", objInfo.CID),
			zap.String("object name", objInfo.Name),
			zap.Stringer("object id", objInfo.ID),
			zap.Error(err))
	}

	return objInfo, nil
}

// objectDelete puts tombstone object into neofs.
func (n *layer) objectDelete(ctx context.Context, cid *cid.ID, oid *oid.ID) error {
	addr := newAddress(cid, oid)
	n.objCache.Delete(addr)
	err := n.pool.DeleteObject(ctx, *addr, n.CallOptions(ctx)...)
	return n.transformNeofsError(ctx, err)
}

// ListObjectsV1 returns objects in a bucket for requests of Version 1.
func (n *layer) ListObjectsV1(ctx context.Context, p *ListObjectsParamsV1) (*ListObjectsInfoV1, error) {
	var (
		err        error
		result     ListObjectsInfoV1
		allObjects []*data.ObjectInfo
	)

	if p.MaxKeys == 0 {
		return &result, nil
	}

	if allObjects, err = n.listAllObjects(ctx, p.ListObjectsParamsCommon); err != nil {
		return nil, err
	}

	if len(allObjects) == 0 {
		return &result, nil
	}

	if p.Marker != "" {
		allObjects = trimAfterObjectName(p.Marker, allObjects)
	}

	if len(allObjects) > p.MaxKeys {
		result.IsTruncated = true
		allObjects = allObjects[:p.MaxKeys]
		result.NextMarker = allObjects[len(allObjects)-1].Name
	}

	result.Prefixes, result.Objects = triageObjects(allObjects)

	return &result, nil
}

// ListObjectsV2 returns objects in a bucket for requests of Version 2.
func (n *layer) ListObjectsV2(ctx context.Context, p *ListObjectsParamsV2) (*ListObjectsInfoV2, error) {
	var (
		err        error
		result     ListObjectsInfoV2
		allObjects []*data.ObjectInfo
	)

	if p.MaxKeys == 0 {
		return &result, nil
	}

	if allObjects, err = n.listAllObjects(ctx, p.ListObjectsParamsCommon); err != nil {
		return nil, err
	}

	if len(allObjects) == 0 {
		return &result, nil
	}

	if p.ContinuationToken != "" {
		allObjects = trimAfterObjectID(p.ContinuationToken, allObjects)
	}

	if p.StartAfter != "" {
		allObjects = trimAfterObjectName(p.StartAfter, allObjects)
	}

	if len(allObjects) > p.MaxKeys {
		result.IsTruncated = true
		allObjects = allObjects[:p.MaxKeys]
		result.NextContinuationToken = allObjects[len(allObjects)-1].ID.String()
	}

	result.Prefixes, result.Objects = triageObjects(allObjects)

	return &result, nil
}

func (n *layer) listSortedObjects(ctx context.Context, p allObjectParams) ([]*data.ObjectInfo, error) {
	versions, err := n.getAllObjectsVersions(ctx, p.Bucket, p.Prefix, p.Delimiter)
	if err != nil {
		return nil, err
	}

	objects := make([]*data.ObjectInfo, 0, len(versions))
	for _, v := range versions {
		lastVersion := v.getLast()
		if lastVersion != nil {
			objects = append(objects, lastVersion)
		}
	}

	sort.Slice(objects, func(i, j int) bool {
		return objects[i].Name < objects[j].Name
	})

	return objects, nil
}

func (n *layer) getAllObjectsVersions(ctx context.Context, bkt *data.BucketInfo, prefix, delimiter string) (map[string]*objectVersions, error) {
	var err error

	cacheKey := cache.CreateObjectsListCacheKey(bkt.CID, prefix)
	ids := n.listsCache.Get(cacheKey)

	if ids == nil {
		ids, err = n.objectSearch(ctx, &findParams{cid: bkt.CID, prefix: prefix})
		if err != nil {
			return nil, err
		}
		if err := n.listsCache.Put(cacheKey, ids); err != nil {
			n.log.Error("couldn't cache list of objects", zap.Error(err))
		}
	}

	versions := make(map[string]*objectVersions, len(ids)/2)

	for i := 0; i < len(ids); i++ {
		obj := n.objectFromObjectsCacheOrNeoFS(ctx, bkt.CID, &ids[i])
		if obj == nil {
			continue
		}
		if oi := objectInfoFromMeta(bkt, obj, prefix, delimiter); oi != nil {
			if isSystem(oi) {
				continue
			}

			objVersions, ok := versions[oi.Name]
			if !ok {
				objVersions = newObjectVersions(oi.Name)
			}
			objVersions.appendVersion(oi)
			versions[oi.Name] = objVersions
		}
	}

	return versions, nil
}

func splitVersions(header string) []string {
	if len(header) == 0 {
		return nil
	}

	return strings.Split(header, ",")
}

func isSystem(obj *data.ObjectInfo) bool {
	return len(obj.Headers[objectSystemAttributeName]) > 0 ||
		len(obj.Headers[attrVersionsIgnore]) > 0
}

func IsSystemHeader(key string) bool {
	return strings.HasPrefix(key, "S3-")
}

func trimAfterObjectName(startAfter string, objects []*data.ObjectInfo) []*data.ObjectInfo {
	if len(objects) != 0 && objects[len(objects)-1].Name <= startAfter {
		return nil
	}
	for i := range objects {
		if objects[i].Name > startAfter {
			return objects[i:]
		}
	}

	return nil
}

func trimAfterObjectID(id string, objects []*data.ObjectInfo) []*data.ObjectInfo {
	if len(objects) != 0 && objects[len(objects)-1].ID.String() == id {
		return []*data.ObjectInfo{}
	}
	for i, obj := range objects {
		if obj.ID.String() == id {
			return objects[i+1:]
		}
	}

	return nil
}

func triageObjects(allObjects []*data.ObjectInfo) (prefixes []string, objects []*data.ObjectInfo) {
	for _, ov := range allObjects {
		if ov.IsDir {
			prefixes = append(prefixes, ov.Name)
		} else {
			objects = append(objects, ov)
		}
	}

	return
}

func (n *layer) listAllObjects(ctx context.Context, p ListObjectsParamsCommon) ([]*data.ObjectInfo, error) {
	var (
		err        error
		bkt        *data.BucketInfo
		allObjects []*data.ObjectInfo
	)

	if bkt, err = n.GetBucketInfo(ctx, p.Bucket); err != nil {
		return nil, err
	}

	allObjects, err = n.listSortedObjects(ctx, allObjectParams{
		Bucket:    bkt,
		Prefix:    p.Prefix,
		Delimiter: p.Delimiter,
	})
	if err != nil {
		return nil, err
	}

	return allObjects, nil
}

func (n *layer) isVersioningEnabled(ctx context.Context, bktInfo *data.BucketInfo) bool {
	settings, err := n.getBucketSettings(ctx, bktInfo)
	if err != nil {
		n.log.Warn("couldn't get versioning settings object", zap.Error(err))
		return false
	}

	return settings.VersioningEnabled
}

func (n *layer) objectFromObjectsCacheOrNeoFS(ctx context.Context, cid *cid.ID, oid *oid.ID) *object.Object {
	var (
		err  error
		meta = n.objCache.Get(newAddress(cid, oid))
	)
	if meta == nil {
		meta, err = n.objectHead(ctx, cid, oid)
		if err != nil {
			n.log.Warn("could not fetch object meta", zap.Error(err))
			return nil
		}
		if err = n.objCache.Put(*meta); err != nil {
			n.log.Error("couldn't cache an object", zap.Error(err))
		}
	}

	return meta
}

func (n *layer) transformNeofsError(ctx context.Context, err error) error {
	if err == nil {
		return nil
	}

	if strings.Contains(err.Error(), "access to operation") && strings.Contains(err.Error(), "is denied by") {
		n.log.Debug("error was transformed", zap.String("request_id", api.GetRequestID(ctx)), zap.Error(err))
		return apiErrors.GetAPIError(apiErrors.ErrAccessDenied)
	}

	return err
}