package putsvc

import (
	"bytes"
	"context"
	"crypto/sha256"
	"errors"
	"fmt"
	"hash"
	"sync"

	objectAPI "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc"
	rawclient "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc/client"
	sessionV2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/session"
	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/signature"
	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/client"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/netmap"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/network"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/internal"
	svcutil "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement"
	tracingPkg "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/tracing"
	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/checksum"
	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	"git.frostfs.info/TrueCloudLab/tzhash/tz"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
	"go.uber.org/zap"
)

type putSingleRequestSigner struct {
	req        *objectAPI.PutSingleRequest
	keyStorage *svcutil.KeyStorage
	signer     *sync.Once
}

func (s *putSingleRequestSigner) GetRequestWithSignedHeader() (*objectAPI.PutSingleRequest, error) {
	var resErr error
	s.signer.Do(func() {
		metaHdr := new(sessionV2.RequestMetaHeader)
		meta := s.req.GetMetaHeader()

		metaHdr.SetTTL(meta.GetTTL() - 1)
		metaHdr.SetOrigin(meta)
		s.req.SetMetaHeader(metaHdr)

		privateKey, err := s.keyStorage.GetKey(nil)
		if err != nil {
			resErr = err
			return
		}
		resErr = signature.SignServiceMessage(privateKey, s.req)
	})
	return s.req, resErr
}

func (s *Service) PutSingle(ctx context.Context, req *objectAPI.PutSingleRequest) (*objectAPI.PutSingleResponse, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "putsvc.PutSingle")
	defer span.End()

	obj := objectSDK.NewFromV2(req.GetBody().GetObject())

	meta, err := s.validatePutSingle(ctx, obj)
	if err != nil {
		return nil, err
	}

	if err := s.saveToNodes(ctx, obj, req, meta); err != nil {
		return nil, err
	}

	resp := &objectAPI.PutSingleResponse{}
	resp.SetBody(&objectAPI.PutSingleResponseBody{})
	return resp, nil
}

func (s *Service) validatePutSingle(ctx context.Context, obj *objectSDK.Object) (object.ContentMeta, error) {
	if err := s.validarePutSingleSize(obj); err != nil {
		return object.ContentMeta{}, err
	}

	if err := s.validatePutSingleChecksum(obj); err != nil {
		return object.ContentMeta{}, err
	}

	return s.validatePutSingleObject(ctx, obj)
}

func (s *Service) validarePutSingleSize(obj *objectSDK.Object) error {
	if uint64(len(obj.Payload())) != obj.PayloadSize() {
		return ErrWrongPayloadSize
	}

	maxAllowedSize := s.maxSizeSrc.MaxObjectSize()
	if obj.PayloadSize() > maxAllowedSize {
		return ErrExceedingMaxSize
	}

	return nil
}

func (s *Service) validatePutSingleChecksum(obj *objectSDK.Object) error {
	cs, csSet := obj.PayloadChecksum()
	if !csSet {
		return errors.New("missing payload checksum")
	}

	var hash hash.Hash

	switch typ := cs.Type(); typ {
	default:
		return fmt.Errorf("unsupported payload checksum type %v", typ)
	case checksum.SHA256:
		hash = sha256.New()
	case checksum.TZ:
		hash = tz.New()
	}

	if _, err := hash.Write(obj.Payload()); err != nil {
		return fmt.Errorf("could not compute payload hash: %w", err)
	}

	if !bytes.Equal(hash.Sum(nil), cs.Value()) {
		return fmt.Errorf("incorrect payload checksum")
	}

	return nil
}

func (s *Service) validatePutSingleObject(ctx context.Context, obj *objectSDK.Object) (object.ContentMeta, error) {
	if err := s.fmtValidator.Validate(ctx, obj, false); err != nil {
		return object.ContentMeta{}, fmt.Errorf("coud not validate object format: %w", err)
	}

	meta, err := s.fmtValidator.ValidateContent(obj)
	if err != nil {
		return object.ContentMeta{}, fmt.Errorf("could not validate payload content: %w", err)
	}

	return meta, nil
}

func (s *Service) saveToNodes(ctx context.Context, obj *objectSDK.Object, req *objectAPI.PutSingleRequest, meta object.ContentMeta) error {
	localOnly := req.GetMetaHeader().GetTTL() <= 1
	placementOptions, err := s.getPutSinglePlacementOptions(obj, req.GetBody().GetCopiesNumber(), localOnly)
	if err != nil {
		return err
	}

	iter := s.cfg.newNodeIterator(placementOptions)
	iter.extraBroadcastEnabled = needAdditionalBroadcast(obj, localOnly)

	signer := &putSingleRequestSigner{
		req:        req,
		keyStorage: s.keyStorage,
		signer:     &sync.Once{},
	}

	return iter.forEachNode(ctx, func(ctx context.Context, nd nodeDesc) error {
		return s.saveToPlacementNode(ctx, &nd, obj, signer, meta)
	})
}

func (s *Service) getPutSinglePlacementOptions(obj *objectSDK.Object, copiesNumber []uint32, localOnly bool) ([]placement.Option, error) {
	var result []placement.Option
	if len(copiesNumber) > 0 {
		result = append(result, placement.WithCopyNumbers(copiesNumber))
	}

	cnrID, ok := obj.ContainerID()
	if !ok {
		return nil, errors.New("missing container ID")
	}
	cnrInfo, err := s.cnrSrc.Get(cnrID)
	if err != nil {
		return nil, fmt.Errorf("could not get container by ID: %w", err)
	}
	result = append(result, placement.ForContainer(cnrInfo.Value))

	objID, ok := obj.ID()
	if !ok {
		return nil, errors.New("missing object ID")
	}
	result = append(result, placement.ForObject(objID))

	latestNetmap, err := netmap.GetLatestNetworkMap(s.netMapSrc)
	if err != nil {
		return nil, fmt.Errorf("could not get latest network map: %w", err)
	}
	builder := placement.NewNetworkMapBuilder(latestNetmap)
	if localOnly {
		result = append(result, placement.SuccessAfter(1))
		builder = svcutil.NewLocalPlacement(builder, s.netmapKeys)
	}
	result = append(result, placement.UseBuilder(builder))
	return result, nil
}

func (s *Service) saveToPlacementNode(ctx context.Context, nodeDesc *nodeDesc, obj *objectSDK.Object,
	signer *putSingleRequestSigner, meta object.ContentMeta,
) error {
	if nodeDesc.local {
		return s.saveLocal(ctx, obj, meta)
	}

	var info client.NodeInfo

	client.NodeInfoFromNetmapElement(&info, nodeDesc.info)

	c, err := s.clientConstructor.Get(info)
	if err != nil {
		return fmt.Errorf("could not create SDK client %s: %w", info.AddressGroup(), err)
	}

	return s.redirectPutSingleRequest(ctx, signer, obj, info, c)
}

func (s *Service) saveLocal(ctx context.Context, obj *objectSDK.Object, meta object.ContentMeta) error {
	localTarget := &localTarget{
		storage: s.localStore,
	}
	return localTarget.WriteObject(ctx, obj, meta)
}

func (s *Service) redirectPutSingleRequest(ctx context.Context,
	signer *putSingleRequestSigner,
	obj *objectSDK.Object,
	info client.NodeInfo,
	c client.MultiAddressClient,
) error {
	ctx, span := tracing.StartSpanFromContext(ctx, "putService.redirectPutSingleRequest")
	defer span.End()

	var req *objectAPI.PutSingleRequest
	var firstErr error
	req, firstErr = signer.GetRequestWithSignedHeader()
	if firstErr != nil {
		return firstErr
	}

	info.AddressGroup().IterateAddresses(func(addr network.Address) (stop bool) {
		ctx, span := tracing.StartSpanFromContext(ctx, "putService.redirectPutSingleRequest.IterateAddresses",
			trace.WithAttributes(
				attribute.String("address", addr.String())))
		defer span.End()

		var err error

		defer func() {
			if err != nil {
				objID, _ := obj.ID()
				cnrID, _ := obj.ContainerID()
				s.log.Warn(logs.PutSingleRedirectFailure,
					zap.Error(err),
					zap.Stringer("address", addr),
					zap.Stringer("object_id", objID),
					zap.Stringer("container_id", cnrID),
					zap.String("trace_id", tracingPkg.GetTraceID(ctx)),
				)
			}

			stop = err == nil
			if stop || firstErr == nil {
				firstErr = err
			}
		}()

		var resp *objectAPI.PutSingleResponse

		err = c.RawForAddress(ctx, addr, func(cli *rawclient.Client) error {
			var e error
			resp, e = rpc.PutSingleObject(cli, req, rawclient.WithContext(ctx))
			return e
		})
		if err != nil {
			err = fmt.Errorf("failed to execute request: %w", err)
			return
		}

		if err = internal.VerifyResponseKeyV2(info.PublicKey(), resp); err != nil {
			return
		}

		err = signature.VerifyServiceMessage(resp)
		if err != nil {
			err = fmt.Errorf("response verification failed: %w", err)
		}

		return
	})

	return firstErr
}