package validator

import (
	"context"
	"time"

	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
	"github.com/prysmaticlabs/prysm/shared/bytesutil"

	ptypes "github.com/gogo/protobuf/types"
	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
	"github.com/prysmaticlabs/prysm/beacon-chain/cache/depositcache"
	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
	blockfeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/block"
	opfeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/operation"
	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
	"github.com/prysmaticlabs/prysm/beacon-chain/db"
	"github.com/prysmaticlabs/prysm/beacon-chain/operations/attestations"
	"github.com/prysmaticlabs/prysm/beacon-chain/operations/slashings"
	"github.com/prysmaticlabs/prysm/beacon-chain/operations/voluntaryexits"
	"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
	"github.com/prysmaticlabs/prysm/beacon-chain/sync"
	pbp2p "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
	"github.com/sirupsen/logrus"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

var log logrus.FieldLogger

func init() {
	log = logrus.WithField("prefix", "rpc/validator")
}

// Server defines a server implementation of the gRPC Validator service,
// providing RPC endpoints for obtaining validator assignments per epoch, the slots
// and committees in which particular validators need to perform their responsibilities,
// and more.
type Server struct {
	Ctx                    context.Context
	BeaconDB               db.NoHeadAccessDatabase
	AttestationCache       *cache.AttestationCache
	HeadFetcher            blockchain.HeadFetcher
	ForkFetcher            blockchain.ForkFetcher
	FinalizationFetcher    blockchain.FinalizationFetcher
	TimeFetcher            blockchain.TimeFetcher
	CanonicalStateChan     chan *pbp2p.BeaconState
	BlockFetcher           powchain.POWBlockFetcher
	DepositFetcher         depositcache.DepositFetcher
	ChainStartFetcher      powchain.ChainStartFetcher
	Eth1InfoFetcher        powchain.ChainInfoFetcher
	GenesisTimeFetcher     blockchain.TimeFetcher
	SyncChecker            sync.Checker
	StateNotifier          statefeed.Notifier
	BlockNotifier          blockfeed.Notifier
	P2P                    p2p.Broadcaster
	AttPool                attestations.Pool
	SlashingsPool          *slashings.Pool
	ExitPool               *voluntaryexits.Pool
	BlockReceiver          blockchain.BlockReceiver
	MockEth1Votes          bool
	Eth1BlockFetcher       powchain.POWBlockFetcher
	PendingDepositsFetcher depositcache.PendingDepositsFetcher
	OperationNotifier      opfeed.Notifier
	StateGen               *stategen.State
}

// WaitForActivation checks if a validator public key exists in the active validator registry of the current
// beacon state, if not, then it creates a stream which listens for canonical states which contain
// the validator with the public key as an active validator record.
func (vs *Server) WaitForActivation(req *ethpb.ValidatorActivationRequest, stream ethpb.BeaconNodeValidator_WaitForActivationServer) error {
	activeValidatorExists, validatorStatuses, err := vs.multipleValidatorStatus(stream.Context(), req.PublicKeys)
	if err != nil {
		return status.Errorf(codes.Internal, "Could not fetch validator status: %v", err)
	}
	res := &ethpb.ValidatorActivationResponse{
		Statuses: validatorStatuses,
	}
	if activeValidatorExists {
		return stream.Send(res)
	}
	if err := stream.Send(res); err != nil {
		return status.Errorf(codes.Internal, "Could not send response over stream: %v", err)
	}

	for {
		select {
		case <-time.After(6 * time.Second):
			activeValidatorExists, validatorStatuses, err := vs.multipleValidatorStatus(stream.Context(), req.PublicKeys)
			if err != nil {
				return status.Errorf(codes.Internal, "Could not fetch validator status: %v", err)
			}
			res := &ethpb.ValidatorActivationResponse{
				Statuses: validatorStatuses,
			}
			if activeValidatorExists {
				return stream.Send(res)
			}
			if err := stream.Send(res); err != nil {
				return status.Errorf(codes.Internal, "Could not send response over stream: %v", err)
			}
		case <-stream.Context().Done():
			return status.Error(codes.Canceled, "Stream context canceled")
		case <-vs.Ctx.Done():
			return status.Error(codes.Canceled, "RPC context canceled")
		}
	}
}

// ValidatorIndex is called by a validator to get its index location in the beacon state.
func (vs *Server) ValidatorIndex(ctx context.Context, req *ethpb.ValidatorIndexRequest) (*ethpb.ValidatorIndexResponse, error) {
	st, err := vs.HeadFetcher.HeadState(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "Could not determine head state: %v", err)
	}
	index, ok := st.ValidatorIndexByPubkey(bytesutil.ToBytes48(req.PublicKey))
	if !ok {
		return nil, status.Errorf(codes.Internal, "Could not find validator index for public key %#x not found", req.PublicKey)
	}

	return &ethpb.ValidatorIndexResponse{Index: index}, nil
}

// DomainData fetches the current domain version information from the beacon state.
func (vs *Server) DomainData(ctx context.Context, request *ethpb.DomainRequest) (*ethpb.DomainResponse, error) {
	fork := vs.ForkFetcher.CurrentFork()
	dv, err := helpers.Domain(fork, request.Epoch, bytesutil.ToBytes4(request.Domain))
	if err != nil {
		return nil, err
	}
	return &ethpb.DomainResponse{
		SignatureDomain: dv,
	}, nil
}

// CanonicalHead of the current beacon chain. This method is requested on-demand
// by a validator when it is their time to propose or attest.
func (vs *Server) CanonicalHead(ctx context.Context, req *ptypes.Empty) (*ethpb.SignedBeaconBlock, error) {
	headBlk, err := vs.HeadFetcher.HeadBlock(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "Could not get head block: %v", err)
	}
	return headBlk, nil
}

// WaitForChainStart queries the logs of the Deposit Contract in order to verify the beacon chain
// has started its runtime and validators begin their responsibilities. If it has not, it then
// subscribes to an event stream triggered by the powchain service whenever the ChainStart log does
// occur in the Deposit Contract on ETH 1.0.
func (vs *Server) WaitForChainStart(req *ptypes.Empty, stream ethpb.BeaconNodeValidator_WaitForChainStartServer) error {
	head, err := vs.HeadFetcher.HeadState(context.Background())
	if err != nil {
		return status.Errorf(codes.Internal, "Could not retrieve head state: %v", err)
	}
	if head != nil {
		res := &ethpb.ChainStartResponse{
			Started:     true,
			GenesisTime: head.GenesisTime(),
		}
		return stream.Send(res)
	}

	stateChannel := make(chan *feed.Event, 1)
	stateSub := vs.StateNotifier.StateFeed().Subscribe(stateChannel)
	defer stateSub.Unsubscribe()
	for {
		select {
		case event := <-stateChannel:
			if event.Type == statefeed.ChainStarted {
				data := event.Data.(*statefeed.ChainStartedData)
				log.WithField("starttime", data.StartTime).Debug("Received chain started event")
				log.Info("Sending genesis time notification to connected validator clients")
				res := &ethpb.ChainStartResponse{
					Started:     true,
					GenesisTime: uint64(data.StartTime.Unix()),
				}
				return stream.Send(res)
			}
		case <-stateSub.Err():
			return status.Error(codes.Aborted, "Subscriber closed, exiting goroutine")
		case <-vs.Ctx.Done():
			return status.Error(codes.Canceled, "Context canceled")
		}
	}
}