package layer

import (
	"bytes"
	"context"
	"crypto/rand"
	"crypto/sha256"
	"errors"
	"fmt"
	"io"
	"time"

	v2container "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/container"
	objectv2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/middleware"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/bearer"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/checksum"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	"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/eacl"
	"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/session"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/user"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
)

type FeatureSettingsMock struct {
	clientCut  bool
	md5Enabled bool
}

func (k *FeatureSettingsMock) BufferMaxSizeForPut() uint64 {
	return 0
}

func (k *FeatureSettingsMock) ClientCut() bool {
	return k.clientCut
}

func (k *FeatureSettingsMock) SetClientCut(clientCut bool) {
	k.clientCut = clientCut
}

func (k *FeatureSettingsMock) MD5Enabled() bool {
	return k.md5Enabled
}

func (k *FeatureSettingsMock) SetMD5Enabled(md5Enabled bool) {
	k.md5Enabled = md5Enabled
}

func (k *FeatureSettingsMock) FormContainerZone(ns string) (zone string, isDefault bool) {
	if ns == "" {
		return v2container.SysAttributeZoneDefault, true
	}

	return ns + ".ns", false
}

type TestFrostFS struct {
	FrostFS

	objects         map[string]*object.Object
	objectErrors    map[string]error
	objectPutErrors map[string]error
	containers      map[string]*container.Container
	eaclTables      map[string]*eacl.Table
	currentEpoch    uint64
	key             *keys.PrivateKey
}

func NewTestFrostFS(key *keys.PrivateKey) *TestFrostFS {
	return &TestFrostFS{
		objects:         make(map[string]*object.Object),
		objectErrors:    make(map[string]error),
		objectPutErrors: make(map[string]error),
		containers:      make(map[string]*container.Container),
		eaclTables:      make(map[string]*eacl.Table),
		key:             key,
	}
}

func (t *TestFrostFS) CurrentEpoch() uint64 {
	return t.currentEpoch
}

func (t *TestFrostFS) SetObjectError(addr oid.Address, err error) {
	if err == nil {
		delete(t.objectErrors, addr.EncodeToString())
	} else {
		t.objectErrors[addr.EncodeToString()] = err
	}
}

func (t *TestFrostFS) SetObjectPutError(fileName string, err error) {
	if err == nil {
		delete(t.objectPutErrors, fileName)
	} else {
		t.objectPutErrors[fileName] = err
	}
}

func (t *TestFrostFS) Objects() []*object.Object {
	res := make([]*object.Object, 0, len(t.objects))

	for _, obj := range t.objects {
		res = append(res, obj)
	}

	return res
}

func (t *TestFrostFS) ObjectExists(objID oid.ID) bool {
	for _, obj := range t.objects {
		if id, _ := obj.ID(); id.Equals(objID) {
			return true
		}
	}

	return false
}

func (t *TestFrostFS) AddObject(key string, obj *object.Object) {
	t.objects[key] = obj
}

func (t *TestFrostFS) ContainerID(name string) (cid.ID, error) {
	for id, cnr := range t.containers {
		if container.Name(*cnr) == name {
			var cnrID cid.ID
			return cnrID, cnrID.DecodeString(id)
		}
	}
	return cid.ID{}, fmt.Errorf("not found")
}

func (t *TestFrostFS) SetContainer(cnrID cid.ID, cnr *container.Container) {
	t.containers[cnrID.EncodeToString()] = cnr
}

func (t *TestFrostFS) CreateContainer(_ context.Context, prm PrmContainerCreate) (*ContainerCreateResult, error) {
	var cnr container.Container
	cnr.Init()
	cnr.SetOwner(prm.Creator)
	cnr.SetPlacementPolicy(prm.Policy)
	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])
	}

	b := make([]byte, 32)
	if _, err := io.ReadFull(rand.Reader, b); err != nil {
		return nil, err
	}

	var id cid.ID
	id.SetSHA256(sha256.Sum256(b))
	t.containers[id.EncodeToString()] = &cnr

	return &ContainerCreateResult{ContainerID: id}, nil
}

func (t *TestFrostFS) DeleteContainer(_ context.Context, cnrID cid.ID, _ *session.Container) error {
	delete(t.containers, cnrID.EncodeToString())

	return nil
}

func (t *TestFrostFS) Container(_ context.Context, prm PrmContainer) (*container.Container, error) {
	for k, v := range t.containers {
		if k == prm.ContainerID.EncodeToString() {
			return v, nil
		}
	}

	return nil, fmt.Errorf("container not found %s", prm.ContainerID)
}

func (t *TestFrostFS) UserContainers(context.Context, PrmUserContainers) ([]cid.ID, error) {
	var res []cid.ID
	for k := range t.containers {
		var idCnr cid.ID
		if err := idCnr.DecodeString(k); err != nil {
			return nil, err
		}
		res = append(res, idCnr)
	}

	return res, nil
}

func (t *TestFrostFS) ReadObject(ctx context.Context, prm PrmObjectRead) (*ObjectPart, error) {
	var addr oid.Address
	addr.SetContainer(prm.Container)
	addr.SetObject(prm.Object)

	sAddr := addr.EncodeToString()

	if err := t.objectErrors[sAddr]; err != nil {
		return nil, err
	}

	if obj, ok := t.objects[sAddr]; ok {
		owner := getBearerOwner(ctx)
		if !t.checkAccess(prm.Container, owner, eacl.OperationGet) {
			return nil, ErrAccessDenied
		}

		payload := obj.Payload()

		if prm.PayloadRange[0]+prm.PayloadRange[1] > 0 {
			off := prm.PayloadRange[0]
			payload = payload[off : off+prm.PayloadRange[1]]
		}

		return &ObjectPart{
			Head:    obj,
			Payload: io.NopCloser(bytes.NewReader(payload)),
		}, nil
	}

	return nil, fmt.Errorf("%w: %s", &apistatus.ObjectNotFound{}, addr)
}

func (t *TestFrostFS) CreateObject(_ context.Context, prm PrmObjectCreate) (oid.ID, error) {
	b := make([]byte, 32)
	if _, err := io.ReadFull(rand.Reader, b); err != nil {
		return oid.ID{}, err
	}
	var id oid.ID
	id.SetSHA256(sha256.Sum256(b))

	attrs := make([]object.Attribute, 0)

	if err := t.objectPutErrors[prm.Filepath]; err != nil {
		return oid.ID{}, err
	}

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

	if prm.ClientCut {
		a := object.NewAttribute()
		a.SetKey("s3-client-cut")
		a.SetValue("true")
		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)
	}

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

	obj := object.New()
	obj.SetContainerID(prm.Container)
	obj.SetID(id)
	obj.SetPayloadSize(prm.PayloadSize)
	obj.SetAttributes(attrs...)
	obj.SetCreationEpoch(t.currentEpoch)
	obj.SetOwnerID(owner)
	t.currentEpoch++

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

	if prm.Payload != nil {
		all, err := io.ReadAll(prm.Payload)
		if err != nil {
			return oid.ID{}, err
		}
		obj.SetPayload(all)
		obj.SetPayloadSize(uint64(len(all)))
		var hash checksum.Checksum
		checksum.Calculate(&hash, checksum.SHA256, all)
		obj.SetPayloadChecksum(hash)
	}

	cnrID, _ := obj.ContainerID()
	objID, _ := obj.ID()

	addr := newAddress(cnrID, objID)
	t.objects[addr.EncodeToString()] = obj
	return objID, nil
}

func (t *TestFrostFS) DeleteObject(ctx context.Context, prm PrmObjectDelete) error {
	var addr oid.Address
	addr.SetContainer(prm.Container)
	addr.SetObject(prm.Object)

	if err := t.objectErrors[addr.EncodeToString()]; err != nil {
		return err
	}

	if _, ok := t.objects[addr.EncodeToString()]; ok {
		owner := getBearerOwner(ctx)
		if !t.checkAccess(prm.Container, owner, eacl.OperationDelete) {
			return ErrAccessDenied
		}

		delete(t.objects, addr.EncodeToString())
	}

	return nil
}

func (t *TestFrostFS) TimeToEpoch(_ context.Context, now, futureTime time.Time) (uint64, uint64, error) {
	return t.currentEpoch, t.currentEpoch + uint64(futureTime.Sub(now).Seconds()), nil
}

func (t *TestFrostFS) AllObjects(cnrID cid.ID) []oid.ID {
	result := make([]oid.ID, 0, len(t.objects))

	for _, val := range t.objects {
		objCnrID, _ := val.ContainerID()
		objObjID, _ := val.ID()
		if cnrID.Equals(objCnrID) {
			result = append(result, objObjID)
		}
	}

	return result
}

func (t *TestFrostFS) SetContainerEACL(_ context.Context, table eacl.Table, _ *session.Container) error {
	cnrID, ok := table.CID()
	if !ok {
		return errors.New("invalid cid")
	}

	if _, ok = t.containers[cnrID.EncodeToString()]; !ok {
		return errors.New("not found")
	}

	t.eaclTables[cnrID.EncodeToString()] = &table

	return nil
}

func (t *TestFrostFS) ContainerEACL(_ context.Context, prm PrmContainerEACL) (*eacl.Table, error) {
	table, ok := t.eaclTables[prm.ContainerID.EncodeToString()]
	if !ok {
		return nil, errors.New("not found")
	}

	return table, nil
}

func (t *TestFrostFS) checkAccess(cnrID cid.ID, owner user.ID, op eacl.Operation) bool {
	cnr, ok := t.containers[cnrID.EncodeToString()]
	if !ok {
		return false
	}

	if !cnr.BasicACL().Extendable() {
		return cnr.Owner().Equals(owner)
	}

	table, ok := t.eaclTables[cnrID.EncodeToString()]
	if !ok {
		return true
	}

	for _, rec := range table.Records() {
		if rec.Operation() == op && len(rec.Filters()) == 0 {
			for _, trgt := range rec.Targets() {
				if trgt.Role() == eacl.RoleOthers {
					return rec.Action() == eacl.ActionAllow
				}
				var targetOwner user.ID
				for _, pk := range eacl.TargetECDSAKeys(&trgt) {
					user.IDFromKey(&targetOwner, *pk)
					if targetOwner.Equals(owner) {
						return rec.Action() == eacl.ActionAllow
					}
				}
			}
		}
	}

	return true
}

func getBearerOwner(ctx context.Context) user.ID {
	if bd, err := middleware.GetBoxData(ctx); err == nil && bd.Gate.BearerToken != nil {
		return bearer.ResolveIssuer(*bd.Gate.BearerToken)
	}

	return user.ID{}
}