package frostfs

import (
	"context"
	"errors"
	"fmt"
	"io"
	"math"
	"strconv"
	"time"

	objectv2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer/frostfs"
	frosterr "git.frostfs.info/TrueCloudLab/frostfs-s3-gw/internal/frostfs/errors"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/session"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/user"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
)

// FrostFS represents virtual connection to the FrostFS network.
// It is used to provide an interface to dependent packages
// which work with FrostFS.
type FrostFS struct {
	pool  *pool.Pool
	await pool.WaitParams
	owner user.ID
}

const (
	defaultPollInterval = time.Second       // overrides default value from pool
	defaultPollTimeout  = 120 * time.Second // same as default value from pool
)

// NewFrostFS creates new FrostFS using provided pool.Pool.
func NewFrostFS(p *pool.Pool, key *keys.PrivateKey) *FrostFS {
	await := pool.WaitParams{PollInterval: defaultPollInterval, Timeout: defaultPollTimeout}

	var owner user.ID
	user.IDFromKey(&owner, key.PrivateKey.PublicKey)

	return &FrostFS{
		pool:  p,
		await: await,
		owner: owner,
	}
}

// TimeToEpoch implements layer.FrostFS interface method.
func (x *FrostFS) TimeToEpoch(ctx context.Context, now, futureTime time.Time) (uint64, uint64, error) {
	dur := futureTime.Sub(now)
	if dur < 0 {
		return 0, 0, fmt.Errorf("time '%s' must be in the future (after %s)",
			futureTime.Format(time.RFC3339), now.Format(time.RFC3339))
	}

	networkInfo, err := x.pool.NetworkInfo(ctx)
	if err != nil {
		return 0, 0, handleObjectError("get network info via client", err)
	}

	durEpoch := networkInfo.EpochDuration()
	if durEpoch == 0 {
		return 0, 0, errors.New("epoch duration is missing or zero")
	}

	curr := networkInfo.CurrentEpoch()
	msPerEpoch := durEpoch * uint64(networkInfo.MsPerBlock())

	epochLifetime := uint64(dur.Milliseconds()) / msPerEpoch
	if uint64(dur.Milliseconds())%msPerEpoch != 0 {
		epochLifetime++
	}

	var epoch uint64
	if epochLifetime >= math.MaxUint64-curr {
		epoch = math.MaxUint64
	} else {
		epoch = curr + epochLifetime
	}

	return curr, epoch, nil
}

// Container implements layer.FrostFS interface method.
func (x *FrostFS) Container(ctx context.Context, layerPrm frostfs.PrmContainer) (*container.Container, error) {
	prm := pool.PrmContainerGet{
		ContainerID: layerPrm.ContainerID,
		Session:     layerPrm.SessionToken,
	}

	res, err := x.pool.GetContainer(ctx, prm)
	if err != nil {
		return nil, handleObjectError("read container via connection pool", err)
	}

	return &res, nil
}

// CreateContainer implements layer.FrostFS interface method.
func (x *FrostFS) CreateContainer(ctx context.Context, prm frostfs.PrmContainerCreate) (*frostfs.ContainerCreateResult, error) {
	var cnr container.Container
	cnr.Init()
	cnr.SetPlacementPolicy(prm.Policy)
	cnr.SetOwner(prm.Creator)
	cnr.SetBasicACL(prm.BasicACL)

	creationTime := prm.CreationTime
	if creationTime.IsZero() {
		creationTime = time.Now()
	}
	container.SetCreationTime(&cnr, creationTime)

	if prm.Name != "" {
		var d container.Domain
		d.SetName(prm.Name)
		d.SetZone(prm.Zone)

		container.WriteDomain(&cnr, d)
		container.SetName(&cnr, prm.Name)
	}

	for i := range prm.AdditionalAttributes {
		cnr.SetAttribute(prm.AdditionalAttributes[i][0], prm.AdditionalAttributes[i][1])
	}

	err := pool.SyncContainerWithNetwork(ctx, &cnr, x.pool)
	if err != nil {
		return nil, handleObjectError("sync container with the network state", err)
	}

	prmPut := pool.PrmContainerPut{
		ClientParams: client.PrmContainerPut{
			Container: &cnr,
			Session:   prm.SessionToken,
		},
		WaitParams: &x.await,
	}

	// send request to save the container
	idCnr, err := x.pool.PutContainer(ctx, prmPut)
	return &frostfs.ContainerCreateResult{
		ContainerID:             idCnr,
		HomomorphicHashDisabled: container.IsHomomorphicHashingDisabled(cnr),
	}, handleObjectError("save container via connection pool", err)
}

// UserContainers implements layer.FrostFS interface method.
func (x *FrostFS) UserContainers(ctx context.Context, layerPrm frostfs.PrmUserContainers) ([]cid.ID, error) {
	prm := pool.PrmContainerList{
		OwnerID: layerPrm.UserID,
		Session: layerPrm.SessionToken,
	}

	r, err := x.pool.ListContainers(ctx, prm)
	return r, handleObjectError("list user containers via connection pool", err)
}

// DeleteContainer implements layer.FrostFS interface method.
func (x *FrostFS) DeleteContainer(ctx context.Context, id cid.ID, token *session.Container) error {
	prm := pool.PrmContainerDelete{ContainerID: id, Session: token, WaitParams: &x.await}

	err := x.pool.DeleteContainer(ctx, prm)
	return handleObjectError("delete container via connection pool", err)
}

// CreateObject implements layer.FrostFS interface method.
func (x *FrostFS) CreateObject(ctx context.Context, prm frostfs.PrmObjectCreate) (*frostfs.CreateObjectResult, error) {
	attrNum := len(prm.Attributes) + 1 // + creation time

	if prm.Filepath != "" {
		attrNum++
	}

	attrs := make([]object.Attribute, 0, attrNum)
	var a *object.Attribute

	a = object.NewAttribute()
	a.SetKey(object.AttributeTimestamp)

	creationTime := prm.CreationTime
	if creationTime.IsZero() {
		creationTime = time.Now()
	}
	a.SetValue(strconv.FormatInt(creationTime.Unix(), 10))

	attrs = append(attrs, *a)

	for i := range prm.Attributes {
		a = object.NewAttribute()
		a.SetKey(prm.Attributes[i][0])
		a.SetValue(prm.Attributes[i][1])
		attrs = append(attrs, *a)
	}

	if prm.Filepath != "" {
		a = object.NewAttribute()
		a.SetKey(object.AttributeFilePath)
		a.SetValue(prm.Filepath)
		attrs = append(attrs, *a)
	}

	obj := object.New()
	obj.SetContainerID(prm.Container)
	obj.SetOwnerID(x.owner)
	obj.SetAttributes(attrs...)
	obj.SetPayloadSize(prm.PayloadSize)

	if prm.BearerToken == nil && prm.PrivateKey != nil {
		var owner user.ID
		user.IDFromKey(&owner, prm.PrivateKey.PublicKey)
		obj.SetOwnerID(owner)
	}

	if len(prm.Locks) > 0 {
		lock := new(object.Lock)
		lock.WriteMembers(prm.Locks)
		objectv2.WriteLock(obj.ToV2(), (objectv2.Lock)(*lock))
	}

	var prmPut pool.PrmObjectPut
	prmPut.SetHeader(*obj)
	prmPut.SetPayload(prm.Payload)
	prmPut.SetCopiesNumberVector(prm.CopiesNumber)
	prmPut.SetClientCut(prm.ClientCut)
	prmPut.WithoutHomomorphicHash(prm.WithoutHomomorphicHash)
	prmPut.SetBufferMaxSize(prm.BufferMaxSize)

	if prm.BearerToken != nil {
		prmPut.UseBearer(*prm.BearerToken)
	} else {
		prmPut.UseKey(prm.PrivateKey)
	}

	res, err := x.pool.PutObject(ctx, prmPut)
	if err = handleObjectError("save object via connection pool", err); err != nil {
		return nil, err
	}

	return &frostfs.CreateObjectResult{
		ObjectID:      res.ObjectID,
		CreationEpoch: res.Epoch,
	}, nil
}

// wraps io.ReadCloser and transforms Read errors related to access violation
// to frostfs.ErrAccessDenied.
type payloadReader struct {
	io.ReadCloser
}

func (x payloadReader) Read(p []byte) (int, error) {
	n, err := x.ReadCloser.Read(p)
	if err != nil && errors.Is(err, io.EOF) {
		return n, err
	}
	return n, handleObjectError("read payload", err)
}

// HeadObject implements layer.FrostFS interface method.
func (x *FrostFS) HeadObject(ctx context.Context, prm frostfs.PrmObjectHead) (*object.Object, error) {
	var addr oid.Address
	addr.SetContainer(prm.Container)
	addr.SetObject(prm.Object)

	var prmHead pool.PrmObjectHead
	prmHead.SetAddress(addr)

	if prm.BearerToken != nil {
		prmHead.UseBearer(*prm.BearerToken)
	} else {
		prmHead.UseKey(prm.PrivateKey)
	}

	res, err := x.pool.HeadObject(ctx, prmHead)
	if err != nil {
		return nil, handleObjectError("read object header via connection pool", err)
	}

	return &res, nil
}

// GetObject implements layer.FrostFS interface method.
func (x *FrostFS) GetObject(ctx context.Context, prm frostfs.PrmObjectGet) (*frostfs.Object, error) {
	var addr oid.Address
	addr.SetContainer(prm.Container)
	addr.SetObject(prm.Object)

	var prmGet pool.PrmObjectGet
	prmGet.SetAddress(addr)

	if prm.BearerToken != nil {
		prmGet.UseBearer(*prm.BearerToken)
	} else {
		prmGet.UseKey(prm.PrivateKey)
	}

	res, err := x.pool.GetObject(ctx, prmGet)
	if err != nil {
		return nil, handleObjectError("init full object reading via connection pool", err)
	}

	return &frostfs.Object{
		Header:  res.Header,
		Payload: res.Payload,
	}, nil
}

// RangeObject implements layer.FrostFS interface method.
func (x *FrostFS) RangeObject(ctx context.Context, prm frostfs.PrmObjectRange) (io.ReadCloser, error) {
	var addr oid.Address
	addr.SetContainer(prm.Container)
	addr.SetObject(prm.Object)

	var prmRange pool.PrmObjectRange
	prmRange.SetAddress(addr)
	prmRange.SetOffset(prm.PayloadRange[0])
	prmRange.SetLength(prm.PayloadRange[1])

	if prm.BearerToken != nil {
		prmRange.UseBearer(*prm.BearerToken)
	} else {
		prmRange.UseKey(prm.PrivateKey)
	}

	res, err := x.pool.ObjectRange(ctx, prmRange)
	if err != nil {
		return nil, handleObjectError("init payload range reading via connection pool", err)
	}

	return payloadReader{&res}, nil
}

// DeleteObject implements layer.FrostFS interface method.
func (x *FrostFS) DeleteObject(ctx context.Context, prm frostfs.PrmObjectDelete) error {
	var addr oid.Address
	addr.SetContainer(prm.Container)
	addr.SetObject(prm.Object)

	var prmDelete pool.PrmObjectDelete
	prmDelete.SetAddress(addr)

	if prm.BearerToken != nil {
		prmDelete.UseBearer(*prm.BearerToken)
	} else {
		prmDelete.UseKey(prm.PrivateKey)
	}

	err := x.pool.DeleteObject(ctx, prmDelete)
	return handleObjectError("mark object removal via connection pool", err)
}

// SearchObjects implements layer.FrostFS interface method.
func (x *FrostFS) SearchObjects(ctx context.Context, prm frostfs.PrmObjectSearch) ([]oid.ID, error) {
	filters := object.NewSearchFilters()
	filters.AddRootFilter()

	if prm.ExactAttribute[0] != "" {
		filters.AddFilter(prm.ExactAttribute[0], prm.ExactAttribute[1], object.MatchStringEqual)
	}

	if prm.FilePrefix != "" {
		filters.AddFilter(object.AttributeFileName, prm.FilePrefix, object.MatchCommonPrefix)
	}

	var prmSearch pool.PrmObjectSearch
	prmSearch.SetContainerID(prm.Container)
	prmSearch.SetFilters(filters)

	if prm.BearerToken != nil {
		prmSearch.UseBearer(*prm.BearerToken)
	} else {
		prmSearch.UseKey(prm.PrivateKey)
	}

	res, err := x.pool.SearchObjects(ctx, prmSearch)
	if err != nil {
		return nil, handleObjectError("init object search via connection pool", err)
	}
	defer res.Close()

	var buf []oid.ID
	err = res.Iterate(func(id oid.ID) bool {
		buf = append(buf, id)
		return false
	})
	return buf, handleObjectError("read object list", err)
}

// NetworkInfo implements layer.FrostFS interface method.
func (x *FrostFS) NetworkInfo(ctx context.Context) (netmap.NetworkInfo, error) {
	ni, err := x.pool.NetworkInfo(ctx)
	if err != nil {
		return ni, handleObjectError("get network info via connection pool", err)
	}

	return ni, nil
}

func (x *FrostFS) PatchObject(ctx context.Context, prm frostfs.PrmObjectPatch) (oid.ID, error) {
	var addr oid.Address
	addr.SetContainer(prm.Container)
	addr.SetObject(prm.Object)

	var prmPatch pool.PrmObjectPatch
	prmPatch.SetAddress(addr)

	var rng object.Range
	rng.SetOffset(prm.Offset)
	rng.SetLength(prm.Length)
	if prm.Length+prm.Offset > prm.ObjectSize {
		rng.SetLength(prm.ObjectSize - prm.Offset)
	}

	prmPatch.SetRange(&rng)
	prmPatch.SetPayloadReader(prm.Payload)

	if prm.BearerToken != nil {
		prmPatch.UseBearer(*prm.BearerToken)
	} else {
		prmPatch.UseKey(prm.PrivateKey)
	}

	res, err := x.pool.PatchObject(ctx, prmPatch)
	if err != nil {
		return oid.ID{}, handleObjectError("patch object via connection pool", err)
	}

	return res.ObjectID, nil
}

// ResolverFrostFS represents virtual connection to the FrostFS network.
// It implements resolver.FrostFS.
type ResolverFrostFS struct {
	pool *pool.Pool
}

// NewResolverFrostFS creates new ResolverFrostFS using provided pool.Pool.
func NewResolverFrostFS(p *pool.Pool) *ResolverFrostFS {
	return &ResolverFrostFS{pool: p}
}

// SystemDNS implements resolver.FrostFS interface method.
func (x *ResolverFrostFS) SystemDNS(ctx context.Context) (string, error) {
	networkInfo, err := x.pool.NetworkInfo(ctx)
	if err != nil {
		return "", handleObjectError("read network info via client", err)
	}

	domain := networkInfo.RawNetworkParameter("SystemDNS")
	if domain == nil {
		return "", errors.New("system DNS parameter not found or empty")
	}

	return string(domain), nil
}

func handleObjectError(msg string, err error) error {
	if err == nil {
		return nil
	}

	if reason, ok := frosterr.IsErrObjectAccessDenied(err); ok {
		return fmt.Errorf("%s: %w: %s", msg, frostfs.ErrAccessDenied, reason)
	}

	if frosterr.IsTimeoutError(err) {
		return fmt.Errorf("%s: %w: %s", msg, frostfs.ErrGatewayTimeout, err.Error())
	}

	return fmt.Errorf("%s: %w", msg, err)
}

// PoolStatistic is a mediator which implements authmate.FrostFS through pool.Pool.
type PoolStatistic struct {
	pool *pool.Pool
}

// NewPoolStatistic creates new PoolStatistic using provided pool.Pool.
func NewPoolStatistic(p *pool.Pool) *PoolStatistic {
	return &PoolStatistic{pool: p}
}

// Statistic implements interface method.
func (x *PoolStatistic) Statistic() pool.Statistic {
	return x.pool.Statistic()
}