package target

import (
	"errors"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/netmap"
	objectwriter "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/common/writer"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement"
	containerSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/transformer"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/user"
)

func New(prm *objectwriter.Params) (transformer.ChunkedObjectWriter, error) {
	// prepare needed put parameters
	if err := preparePrm(prm); err != nil {
		return nil, fmt.Errorf("could not prepare put parameters: %w", err)
	}

	if prm.Header.Signature() != nil {
		return newUntrustedTarget(prm)
	}
	return newTrustedTarget(prm)
}

func newUntrustedTarget(prm *objectwriter.Params) (transformer.ChunkedObjectWriter, error) {
	maxPayloadSz := prm.Config.MaxSizeSrc.MaxObjectSize()
	if maxPayloadSz == 0 {
		return nil, errors.New("could not obtain max object size parameter")
	}

	if prm.SignRequestPrivateKey == nil {
		nodeKey, err := prm.Config.KeyStorage.GetKey(nil)
		if err != nil {
			return nil, err
		}
		prm.SignRequestPrivateKey = nodeKey
	}

	// prepare untrusted-Put object target
	return &validatingPreparedTarget{
		nextTarget: newInMemoryObjectBuilder(objectwriter.New(prm)),
		fmt:        prm.Config.FormatValidator,

		maxPayloadSz: maxPayloadSz,
	}, nil
}

func newTrustedTarget(prm *objectwriter.Params) (transformer.ChunkedObjectWriter, error) {
	maxPayloadSz := prm.Config.MaxSizeSrc.MaxObjectSize()
	if maxPayloadSz == 0 {
		return nil, errors.New("could not obtain max object size parameter")
	}

	sToken := prm.Common.SessionToken()

	// prepare trusted-Put object target

	// get private token from local storage
	var sessionInfo *util.SessionInfo

	if sToken != nil {
		sessionInfo = &util.SessionInfo{
			ID:    sToken.ID(),
			Owner: sToken.Issuer(),
		}
	}

	key, err := prm.Config.KeyStorage.GetKey(sessionInfo)
	if err != nil {
		return nil, fmt.Errorf("could not receive session key: %w", err)
	}

	// In case session token is missing, the line above returns the default key.
	// If it isn't owner key, replication attempts will fail, thus this check.
	ownerObj := prm.Header.OwnerID()
	if ownerObj.IsEmpty() {
		return nil, errors.New("missing object owner")
	}

	if sToken == nil {
		var ownerSession user.ID
		user.IDFromKey(&ownerSession, key.PublicKey)

		if !ownerObj.Equals(ownerSession) {
			return nil, errors.New("session token is missing but object owner id is different from the default key")
		}
	} else {
		if !ownerObj.Equals(sessionInfo.Owner) {
			return nil, fmt.Errorf("different token issuer and object owner identifiers %s/%s", sessionInfo.Owner, ownerObj)
		}
	}

	if prm.SignRequestPrivateKey == nil {
		prm.SignRequestPrivateKey = key
	}

	return &validatingTarget{
		fmt: prm.Config.FormatValidator,
		nextTarget: transformer.NewPayloadSizeLimiter(transformer.Params{
			Key:                    key,
			NextTargetInit:         func() transformer.ObjectWriter { return objectwriter.New(prm) },
			NetworkState:           prm.Config.NetworkState,
			MaxSize:                maxPayloadSz,
			WithoutHomomorphicHash: containerSDK.IsHomomorphicHashingDisabled(prm.Container),
			SessionToken:           sToken,
		}),
	}, nil
}

func preparePrm(prm *objectwriter.Params) error {
	var err error

	// get latest network map
	nm, err := netmap.GetLatestNetworkMap(prm.Config.NetmapSource)
	if err != nil {
		return fmt.Errorf("could not get latest network map: %w", err)
	}

	idCnr, ok := prm.Header.ContainerID()
	if !ok {
		return errors.New("missing container ID")
	}

	// get container to store the object
	cnrInfo, err := prm.Config.ContainerSource.Get(idCnr)
	if err != nil {
		return fmt.Errorf("could not get container by ID: %w", err)
	}

	prm.Container = cnrInfo.Value

	// add common options
	prm.TraverseOpts = append(prm.TraverseOpts,
		// set processing container
		placement.ForContainer(prm.Container),
	)

	if ech := prm.Header.ECHeader(); ech != nil {
		prm.TraverseOpts = append(prm.TraverseOpts,
			// set identifier of the processing object
			placement.ForObject(ech.Parent()),
		)
	} else if id, ok := prm.Header.ID(); ok {
		prm.TraverseOpts = append(prm.TraverseOpts,
			// set identifier of the processing object
			placement.ForObject(id),
		)
	}

	// create placement builder from network map
	builder := placement.NewNetworkMapBuilder(nm)

	if prm.Common.LocalOnly() {
		// restrict success count to 1 stored copy (to local storage)
		prm.TraverseOpts = append(prm.TraverseOpts, placement.SuccessAfter(1))

		// use local-only placement builder
		builder = util.NewLocalPlacement(builder, prm.Config.NetmapKeys)
	}

	// set placement builder
	prm.TraverseOpts = append(prm.TraverseOpts, placement.UseBuilder(builder))

	return nil
}