package object

import (
	"bytes"
	"context"
	"crypto/sha256"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	core "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/netmap"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/acl"
	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/user"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"go.uber.org/zap"
)

type InnerRing interface {
	InnerRingKeys() ([][]byte, error)
}

type SenderClassifier struct {
	log       *logger.Logger
	innerRing InnerRing
	netmap    core.Source
}

func NewSenderClassifier(innerRing InnerRing, netmap core.Source, log *logger.Logger) SenderClassifier {
	return SenderClassifier{
		log:       log,
		innerRing: innerRing,
		netmap:    netmap,
	}
}

type ClassifyResult struct {
	Role acl.Role
	Key  []byte
}

func (c SenderClassifier) Classify(
	ctx context.Context,
	ownerID *user.ID,
	ownerKey *keys.PublicKey,
	idCnr cid.ID,
	cnr container.Container,
) (res *ClassifyResult, err error) {
	ownerKeyInBytes := ownerKey.Bytes()

	// TODO: #767 get owner from frostfs.id if present

	// if request owner is the same as container owner, return RoleUser
	if ownerID.Equals(cnr.Owner()) {
		return &ClassifyResult{
			Role: acl.RoleOwner,
			Key:  ownerKeyInBytes,
		}, nil
	}

	return c.IsInnerRingOrContainerNode(ctx, ownerKeyInBytes, idCnr, cnr)
}

func (c SenderClassifier) IsInnerRingOrContainerNode(ctx context.Context, ownerKeyInBytes []byte, idCnr cid.ID, cnr container.Container) (*ClassifyResult, error) {
	isInnerRingNode, err := c.isInnerRingKey(ownerKeyInBytes)
	if err != nil {
		// do not throw error, try best case matching
		c.log.Debug(ctx, logs.V2CantCheckIfRequestFromInnerRing,
			zap.String("error", err.Error()))
	} else if isInnerRingNode {
		return &ClassifyResult{
			Role: acl.RoleInnerRing,
			Key:  ownerKeyInBytes,
		}, nil
	}

	binCnr := make([]byte, sha256.Size)
	idCnr.Encode(binCnr)

	isContainerNode, err := c.isContainerKey(ownerKeyInBytes, binCnr, cnr)
	if err != nil {
		// error might happen if request has `RoleOther` key and placement
		// is not possible for previous epoch, so
		// do not throw error, try best case matching
		c.log.Debug(ctx, logs.V2CantCheckIfRequestFromContainerNode,
			zap.String("error", err.Error()))
	} else if isContainerNode {
		return &ClassifyResult{
			Role: acl.RoleContainer,
			Key:  ownerKeyInBytes,
		}, nil
	}

	// if none of above, return RoleOthers
	return &ClassifyResult{
		Role: acl.RoleOthers,
		Key:  ownerKeyInBytes,
	}, nil
}

func (c SenderClassifier) isInnerRingKey(owner []byte) (bool, error) {
	innerRingKeys, err := c.innerRing.InnerRingKeys()
	if err != nil {
		return false, err
	}

	// if request owner key in the inner ring list, return RoleSystem
	for i := range innerRingKeys {
		if bytes.Equal(innerRingKeys[i], owner) {
			return true, nil
		}
	}

	return false, nil
}

func (c SenderClassifier) isContainerKey(
	owner, idCnr []byte,
	cnr container.Container,
) (bool, error) {
	nm, err := core.GetLatestNetworkMap(c.netmap) // first check current netmap
	if err != nil {
		return false, err
	}

	in, err := LookupKeyInContainer(nm, owner, idCnr, cnr)
	if err != nil {
		return false, err
	} else if in {
		return true, nil
	}

	// then check previous netmap, this can happen in-between epoch change
	// when node migrates data from last epoch container
	nm, err = core.GetPreviousNetworkMap(c.netmap)
	if err != nil {
		return false, err
	}

	return LookupKeyInContainer(nm, owner, idCnr, cnr)
}

func LookupKeyInContainer(
	nm *netmap.NetMap,
	pkey, idCnr []byte,
	cnr container.Container,
) (bool, error) {
	cnrVectors, err := nm.ContainerNodes(cnr.PlacementPolicy(), idCnr)
	if err != nil {
		return false, err
	}

	for i := range cnrVectors {
		for j := range cnrVectors[i] {
			if bytes.Equal(cnrVectors[i][j].PublicKey(), pkey) {
				return true, nil
			}
		}
	}

	return false, nil
}