package putsvc

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

	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/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"
	"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())

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

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

	if err := s.validatePutSingleChecksum(obj); err != nil {
		return 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) error {
	if err := s.fmtValidator.Validate(ctx, obj, false); err != nil {
		return fmt.Errorf("coult not validate object format: %w", err)
	}

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

	return nil
}

func (s *Service) saveToNodes(ctx context.Context, obj *objectSDK.Object, req *objectAPI.PutSingleRequest) error {
	localOnly := req.GetMetaHeader().GetTTL() <= 1
	placementOptions, err := s.getPutSinglePlacementOptions(obj, req.GetBody().GetCopiesNumber(), localOnly)
	if err != nil {
		return err
	}
	traversal := &traversal{
		opts: placementOptions,
		extraBroadcastEnabled: len(obj.Children()) > 0 ||
			(!localOnly && (obj.Type() == objectSDK.TypeTombstone || obj.Type() == objectSDK.TypeLock)),
		mtx:      sync.RWMutex{},
		mExclude: make(map[string]struct{}),
	}
	signer := &putSingleRequestSigner{
		req:        req,
		keyStorage: s.keyStorage,
		signer:     &sync.Once{},
	}
	return s.saveAccordingToPlacement(ctx, obj, signer, traversal)
}

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) saveAccordingToPlacement(ctx context.Context, obj *objectSDK.Object, signer *putSingleRequestSigner, traversal *traversal) error {
	traverser, err := placement.NewTraverser(traversal.opts...)
	if err != nil {
		return fmt.Errorf("could not create object placement traverser: %w", err)
	}

	var resultError atomic.Value
	for {
		addrs := traverser.Next()
		if len(addrs) == 0 {
			break
		}

		if stop := s.saveToPlacementNodes(ctx, obj, signer, traversal, traverser, addrs, &resultError); stop {
			break
		}
	}

	if !traverser.Success() {
		var err errIncompletePut
		err.singleErr, _ = resultError.Load().(error)
		return err
	}

	if traversal.submitPrimaryPlacementFinish() {
		err = s.saveAccordingToPlacement(ctx, obj, signer, traversal)
		if err != nil {
			s.log.Error(logs.PutAdditionalContainerBroadcastFailure, zap.Error(err))
		}
	}

	return nil
}

func (s *Service) saveToPlacementNodes(ctx context.Context,
	obj *objectSDK.Object,
	signer *putSingleRequestSigner,
	traversal *traversal,
	traverser *placement.Traverser,
	nodeAddresses []placement.Node,
	resultError *atomic.Value,
) bool {
	wg := sync.WaitGroup{}

	for _, nodeAddress := range nodeAddresses {
		nodeAddress := nodeAddress
		if traversal.processed(nodeAddress) {
			continue
		}

		local := false
		workerPool := s.remotePool
		if s.netmapKeys.IsLocalKey(nodeAddress.PublicKey()) {
			local = true
			workerPool = s.localPool
		}

		wg.Add(1)
		if err := workerPool.Submit(func() {
			defer wg.Done()

			err := s.saveToPlacementNode(ctx, &nodeDesc{local: local, info: nodeAddress}, obj, signer)

			traversal.submitProcessed(nodeAddress)

			if err != nil {
				resultError.Store(err)
				svcutil.LogServiceError(s.log, "PUT", nodeAddress.Addresses(), err)
				return
			}

			traverser.SubmitSuccess()
		}); err != nil {
			wg.Done()
			svcutil.LogWorkerPoolError(s.log, "PUT", err)
			return true
		}
	}

	wg.Wait()

	return false
}

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

	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) 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("failed to redirect PutSingle request",
					zap.Error(err),
					zap.Stringer("address", addr),
					zap.Stringer("object_id", objID),
					zap.Stringer("container_id", cnrID),
				)
			}

			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
}