package evaluators

import (
	"bytes"
	"context"
	"fmt"
	"math"
	"strings"

	log "github.com/sirupsen/logrus"

	"github.com/pkg/errors"
	corehelpers "github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/signing"
	"github.com/prysmaticlabs/prysm/v3/config/params"
	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
	types "github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
	"github.com/prysmaticlabs/prysm/v3/testing/endtoend/helpers"
	e2e "github.com/prysmaticlabs/prysm/v3/testing/endtoend/params"
	"github.com/prysmaticlabs/prysm/v3/testing/endtoend/policies"
	e2etypes "github.com/prysmaticlabs/prysm/v3/testing/endtoend/types"
	"github.com/prysmaticlabs/prysm/v3/testing/util"
	"golang.org/x/exp/rand"
	"google.golang.org/grpc"
	"google.golang.org/protobuf/types/known/emptypb"
)

var exitedVals = make(map[[48]byte]bool)

// churnLimit is normally 4 unless the validator set is extremely large.
var churnLimit = 4
var depositValCount = e2e.DepositCount

// Deposits should be processed in twice the length of the epochs per eth1 voting period.
var depositsInBlockStart = params.E2ETestConfig().EpochsPerEth1VotingPeriod * 2

// deposits included + finalization + MaxSeedLookahead for activation.
var depositActivationStartEpoch = depositsInBlockStart + 2 + params.E2ETestConfig().MaxSeedLookahead
var depositEndEpoch = depositActivationStartEpoch + types.Epoch(math.Ceil(float64(depositValCount)/float64(churnLimit)))

// ProcessesDepositsInBlocks ensures the expected amount of deposits are accepted into blocks.
var ProcessesDepositsInBlocks = e2etypes.Evaluator{
	Name:       "processes_deposits_in_blocks_epoch_%d",
	Policy:     policies.OnEpoch(depositsInBlockStart), // We expect all deposits to enter in one epoch.
	Evaluation: processesDepositsInBlocks,
}

// VerifyBlockGraffiti ensures the block graffiti is one of the random list.
var VerifyBlockGraffiti = e2etypes.Evaluator{
	Name:       "verify_graffiti_in_blocks_epoch_%d",
	Policy:     policies.AfterNthEpoch(0),
	Evaluation: verifyGraffitiInBlocks,
}

// ActivatesDepositedValidators ensures the expected amount of validator deposits are activated into the state.
var ActivatesDepositedValidators = e2etypes.Evaluator{
	Name:       "processes_deposit_validators_epoch_%d",
	Policy:     policies.BetweenEpochs(depositActivationStartEpoch, depositEndEpoch),
	Evaluation: activatesDepositedValidators,
}

// DepositedValidatorsAreActive ensures the expected amount of validators are active after their deposits are processed.
var DepositedValidatorsAreActive = e2etypes.Evaluator{
	Name:       "deposited_validators_are_active_epoch_%d",
	Policy:     policies.AfterNthEpoch(depositEndEpoch),
	Evaluation: depositedValidatorsAreActive,
}

// ProposeVoluntaryExit sends a voluntary exit from randomly selected validator in the genesis set.
var ProposeVoluntaryExit = e2etypes.Evaluator{
	Name:       "propose_voluntary_exit_epoch_%d",
	Policy:     policies.OnEpoch(7),
	Evaluation: proposeVoluntaryExit,
}

// ValidatorsHaveExited checks the beacon state for the exited validator and ensures its marked as exited.
var ValidatorsHaveExited = e2etypes.Evaluator{
	Name:       "voluntary_has_exited_%d",
	Policy:     policies.OnEpoch(8),
	Evaluation: validatorsHaveExited,
}

// ValidatorsVoteWithTheMajority verifies whether validator vote for eth1data using the majority algorithm.
var ValidatorsVoteWithTheMajority = e2etypes.Evaluator{
	Name:       "validators_vote_with_the_majority_%d",
	Policy:     policies.AfterNthEpoch(0),
	Evaluation: validatorsVoteWithTheMajority,
}

type mismatch struct {
	k [48]byte
	e uint64
	o uint64
}

func (m mismatch) String() string {
	return fmt.Sprintf("(%#x:%d:%d)", m.k, m.e, m.o)
}

func processesDepositsInBlocks(ec e2etypes.EvaluationContext, conns ...*grpc.ClientConn) error {
	expected := ec.Balances(e2etypes.PostGenesisDepositBatch)
	conn := conns[0]
	client := ethpb.NewBeaconChainClient(conn)
	chainHead, err := client.GetChainHead(context.Background(), &emptypb.Empty{})
	if err != nil {
		return errors.Wrap(err, "failed to get chain head")
	}

	req := &ethpb.ListBlocksRequest{QueryFilter: &ethpb.ListBlocksRequest_Epoch{Epoch: chainHead.HeadEpoch - 1}}
	blks, err := client.ListBeaconBlocks(context.Background(), req)
	if err != nil {
		return errors.Wrap(err, "failed to get blocks from beacon-chain")
	}
	observed := make(map[[48]byte]uint64)
	for _, blk := range blks.BlockContainers {
		sb, err := blocks.BeaconBlockContainerToSignedBeaconBlock(blk)
		if err != nil {
			return errors.Wrap(err, "failed to convert api response type to SignedBeaconBlock interface")
		}
		b := sb.Block()
		deposits := b.Body().Deposits()
		for _, d := range deposits {
			k := bytesutil.ToBytes48(d.Data.PublicKey)
			v := observed[k]
			observed[k] = v + d.Data.Amount
		}
	}
	mismatches := []string{}
	for k, ev := range expected {
		ov := observed[k]
		if ev != ov {
			mismatches = append(mismatches, mismatch{k: k, e: ev, o: ov}.String())
		}
	}
	if len(mismatches) != 0 {
		return fmt.Errorf("not all expected deposits observed on chain, len(expected)=%d, len(observed)=%d, mismatches=%d; details(key:expected:observed): %s", len(expected), len(observed), len(mismatches), strings.Join(mismatches, ","))
	}
	return nil
}

func verifyGraffitiInBlocks(_ e2etypes.EvaluationContext, conns ...*grpc.ClientConn) error {
	conn := conns[0]
	client := ethpb.NewBeaconChainClient(conn)
	chainHead, err := client.GetChainHead(context.Background(), &emptypb.Empty{})
	if err != nil {
		return errors.Wrap(err, "failed to get chain head")
	}
	begin := chainHead.HeadEpoch
	// Prevent underflow when this runs at epoch 0.
	if begin > 0 {
		begin = begin.Sub(1)
	}
	req := &ethpb.ListBlocksRequest{QueryFilter: &ethpb.ListBlocksRequest_Epoch{Epoch: begin}}
	blks, err := client.ListBeaconBlocks(context.Background(), req)
	if err != nil {
		return errors.Wrap(err, "failed to get blocks from beacon-chain")
	}
	for _, ctr := range blks.BlockContainers {
		blk, err := blocks.BeaconBlockContainerToSignedBeaconBlock(ctr)
		if err != nil {
			return err
		}
		var e bool
		slot := blk.Block().Slot()
		graffitiInBlock := blk.Block().Body().Graffiti()
		for _, graffiti := range helpers.Graffiti {
			if bytes.Equal(bytesutil.PadTo([]byte(graffiti), 32), graffitiInBlock[:]) {
				e = true
				break
			}
		}
		if !e && slot != 0 {
			return errors.New("could not get graffiti from the list")
		}
	}

	return nil
}

func activatesDepositedValidators(ec e2etypes.EvaluationContext, conns ...*grpc.ClientConn) error {
	conn := conns[0]
	client := ethpb.NewBeaconChainClient(conn)

	chainHead, err := client.GetChainHead(context.Background(), &emptypb.Empty{})
	if err != nil {
		return errors.Wrap(err, "failed to get chain head")
	}
	epoch := chainHead.HeadEpoch

	validators, err := getAllValidators(client)
	if err != nil {
		return errors.Wrap(err, "failed to get validators")
	}
	expected := ec.Balances(e2etypes.PostGenesisDepositBatch)

	var deposits, lowBalance, wrongExit, wrongWithdraw int
	for _, v := range validators {
		key := bytesutil.ToBytes48(v.PublicKey)
		if _, ok := expected[key]; !ok {
			continue
		}
		delete(expected, key)
		if v.ActivationEpoch != epoch {
			continue
		}
		deposits++
		if v.EffectiveBalance < params.BeaconConfig().MaxEffectiveBalance {
			lowBalance++
		}
		if v.ExitEpoch != params.BeaconConfig().FarFutureEpoch {
			wrongExit++
		}
		if v.WithdrawableEpoch != params.BeaconConfig().FarFutureEpoch {
			wrongWithdraw++
		}
	}

	// Make sure every post-genesis deposit has been proecssed, resulting in a validator.
	if len(expected) > 0 {
		return fmt.Errorf("missing %d validators for post-genesis deposits", len(expected))
	}

	if deposits != churnLimit {
		return fmt.Errorf("expected %d deposits to be processed in epoch %d, received %d", churnLimit, epoch, deposits)
	}

	if lowBalance > 0 {
		return fmt.Errorf(
			"%d validators did not have genesis validator effective balance of %d",
			lowBalance,
			params.BeaconConfig().MaxEffectiveBalance,
		)
	} else if wrongExit > 0 {
		return fmt.Errorf("%d validators did not have an exit epoch of far future epoch", wrongExit)
	} else if wrongWithdraw > 0 {
		return fmt.Errorf("%d validators did not have a withdrawable epoch of far future epoch", wrongWithdraw)
	}
	return nil
}

func getAllValidators(c ethpb.BeaconChainClient) ([]*ethpb.Validator, error) {
	vals := make([]*ethpb.Validator, 0)
	pageToken := "0"
	for pageToken != "" {
		validatorRequest := &ethpb.ListValidatorsRequest{
			PageSize:  100,
			PageToken: pageToken,
		}
		validators, err := c.ListValidators(context.Background(), validatorRequest)
		if err != nil {
			return nil, errors.Wrap(err, "failed to get validators")
		}
		for _, v := range validators.ValidatorList {
			vals = append(vals, v.Validator)
		}
		pageToken = validators.NextPageToken
		log.WithField("len", len(vals)).WithField("pageToken", pageToken).Info("getAllValidators")
	}
	return vals, nil
}

func depositedValidatorsAreActive(ec e2etypes.EvaluationContext, conns ...*grpc.ClientConn) error {
	conn := conns[0]
	client := ethpb.NewBeaconChainClient(conn)

	chainHead, err := client.GetChainHead(context.Background(), &emptypb.Empty{})
	if err != nil {
		return errors.Wrap(err, "failed to get chain head")
	}

	vals, err := getAllValidators(client)
	if err != nil {
		return errors.Wrap(err, "error retrieving validator list from API")
	}
	inactive := 0
	lowBalance := 0
	nexits := 0
	expected := ec.Balances(e2etypes.PostGenesisDepositBatch)
	nexpected := len(expected)
	for _, v := range vals {
		key := bytesutil.ToBytes48(v.PublicKey)
		if _, ok := expected[key]; !ok {
			continue // we aren't checking for this validator
		}
		// ignore voluntary exits when checking balance and active status
		exited := exitedVals[key]
		if exited {
			nexits++
			delete(expected, key)
			continue
		}
		if !corehelpers.IsActiveValidator(v, chainHead.HeadEpoch) {
			inactive++
		}
		if v.EffectiveBalance < params.BeaconConfig().MaxEffectiveBalance {
			lowBalance++
		}
		delete(expected, key)
	}
	if len(expected) > 0 {
		mk := make([]string, 0)
		for k := range expected {
			mk = append(mk, fmt.Sprintf("%#x", k))
		}
		return fmt.Errorf("API response missing %d validators, based on deposits; keys=%s", len(expected), strings.Join(mk, ","))
	}
	if inactive != 0 || lowBalance != 0 {
		return fmt.Errorf("active validator set does not match %d total deposited. %d exited, %d inactive, %d low balance", nexpected, nexits, inactive, lowBalance)
	}

	return nil
}

func proposeVoluntaryExit(_ e2etypes.EvaluationContext, conns ...*grpc.ClientConn) error {
	conn := conns[0]
	valClient := ethpb.NewBeaconNodeValidatorClient(conn)
	beaconClient := ethpb.NewBeaconChainClient(conn)

	ctx := context.Background()
	chainHead, err := beaconClient.GetChainHead(ctx, &emptypb.Empty{})
	if err != nil {
		return errors.Wrap(err, "could not get chain head")
	}

	deposits, privKeys, err := util.DeterministicDepositsAndKeys(params.BeaconConfig().MinGenesisActiveValidatorCount)
	if err != nil {
		return err
	}

	exitedIndex := types.ValidatorIndex(rand.Uint64() % params.BeaconConfig().MinGenesisActiveValidatorCount)

	voluntaryExit := &ethpb.VoluntaryExit{
		Epoch:          chainHead.HeadEpoch,
		ValidatorIndex: exitedIndex,
	}
	req := &ethpb.DomainRequest{
		Epoch:  chainHead.HeadEpoch,
		Domain: params.BeaconConfig().DomainVoluntaryExit[:],
	}
	domain, err := valClient.DomainData(ctx, req)
	if err != nil {
		return err
	}
	signingData, err := signing.ComputeSigningRoot(voluntaryExit, domain.SignatureDomain)
	if err != nil {
		return err
	}
	signature := privKeys[exitedIndex].Sign(signingData[:])
	signedExit := &ethpb.SignedVoluntaryExit{
		Exit:      voluntaryExit,
		Signature: signature.Marshal(),
	}

	if _, err = valClient.ProposeExit(ctx, signedExit); err != nil {
		return errors.Wrap(err, "could not propose exit")
	}
	pubk := bytesutil.ToBytes48(deposits[exitedIndex].Data.PublicKey)
	exitedVals[pubk] = true

	return nil
}

func validatorsHaveExited(_ e2etypes.EvaluationContext, conns ...*grpc.ClientConn) error {
	conn := conns[0]
	client := ethpb.NewBeaconChainClient(conn)
	for k := range exitedVals {
		validatorRequest := &ethpb.GetValidatorRequest{
			QueryFilter: &ethpb.GetValidatorRequest_PublicKey{
				PublicKey: k[:],
			},
		}
		validator, err := client.GetValidator(context.Background(), validatorRequest)
		if err != nil {
			return errors.Wrap(err, "failed to get validators")
		}
		if validator.ExitEpoch == params.BeaconConfig().FarFutureEpoch {
			return fmt.Errorf("expected validator %#x to be submitted for exit", k)
		}
	}
	return nil
}

func validatorsVoteWithTheMajority(_ e2etypes.EvaluationContext, conns ...*grpc.ClientConn) error {
	conn := conns[0]
	client := ethpb.NewBeaconChainClient(conn)
	chainHead, err := client.GetChainHead(context.Background(), &emptypb.Empty{})
	if err != nil {
		return errors.Wrap(err, "failed to get chain head")
	}

	begin := chainHead.HeadEpoch
	// Prevent underflow when this runs at epoch 0.
	if begin > 0 {
		begin = begin.Sub(1)
	}
	req := &ethpb.ListBlocksRequest{QueryFilter: &ethpb.ListBlocksRequest_Epoch{Epoch: begin}}
	blks, err := client.ListBeaconBlocks(context.Background(), req)
	if err != nil {
		return errors.Wrap(err, "failed to get blocks from beacon-chain")
	}

	slotsPerVotingPeriod := params.E2ETestConfig().SlotsPerEpoch.Mul(uint64(params.E2ETestConfig().EpochsPerEth1VotingPeriod))
	for _, blk := range blks.BlockContainers {
		var slot types.Slot
		var vote []byte
		switch blk.Block.(type) {
		case *ethpb.BeaconBlockContainer_Phase0Block:
			b := blk.GetPhase0Block().Block
			slot = b.Slot
			vote = b.Body.Eth1Data.BlockHash
		case *ethpb.BeaconBlockContainer_AltairBlock:
			b := blk.GetAltairBlock().Block
			slot = b.Slot
			vote = b.Body.Eth1Data.BlockHash
		case *ethpb.BeaconBlockContainer_BellatrixBlock:
			b := blk.GetBellatrixBlock().Block
			slot = b.Slot
			vote = b.Body.Eth1Data.BlockHash
		case *ethpb.BeaconBlockContainer_BlindedBellatrixBlock:
			b := blk.GetBlindedBellatrixBlock().Block
			slot = b.Slot
			vote = b.Body.Eth1Data.BlockHash
		default:
			return errors.New("block neither phase0,altair or bellatrix")
		}

		// We treat epoch 1 differently from other epoch for two reasons:
		// - this evaluator is not executed for epoch 0 so we have to calculate the first slot differently
		// - for some reason the vote for the first slot in epoch 1 is 0x000... so we skip this slot
		var isFirstSlotInVotingPeriod bool
		if chainHead.HeadEpoch == 1 && slot%params.BeaconConfig().SlotsPerEpoch == 0 {
			continue
		}
		// We skipped the first slot so we treat the second slot as the starting slot of epoch 1.
		if chainHead.HeadEpoch == 1 {
			isFirstSlotInVotingPeriod = slot%params.BeaconConfig().SlotsPerEpoch == 1
		} else {
			isFirstSlotInVotingPeriod = slot%slotsPerVotingPeriod == 0
		}
		if isFirstSlotInVotingPeriod {
			expectedEth1DataVote = vote
			return nil
		}

		if !bytes.Equal(vote, expectedEth1DataVote) {
			return fmt.Errorf("incorrect eth1data vote for slot %d; expected: %#x vs voted: %#x",
				slot, expectedEth1DataVote, vote)
		}
	}
	return nil
}

var expectedEth1DataVote []byte