github.com/unicornultrafoundation/go-u2u@v1.0.0-rc1.0.20240205080301-e74a83d3fadc/ethapi/api.go

// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package ethapi

import (
	"context"
	"errors"
	"fmt"
	"math/big"
	"math/rand"
	"runtime"
	"strings"
	"sync"
	"time"

	"github.com/davecgh/go-spew/spew"
	"github.com/syndtr/goleveldb/leveldb/opt"
	"github.com/tyler-smith/go-bip39"

	"github.com/unicornultrafoundation/go-helios/hash"
	"github.com/unicornultrafoundation/go-helios/native/idx"

	"github.com/unicornultrafoundation/go-u2u/accounts"
	"github.com/unicornultrafoundation/go-u2u/accounts/abi"
	"github.com/unicornultrafoundation/go-u2u/accounts/keystore"
	"github.com/unicornultrafoundation/go-u2u/accounts/scwallet"
	"github.com/unicornultrafoundation/go-u2u/common"
	"github.com/unicornultrafoundation/go-u2u/common/hexutil"
	"github.com/unicornultrafoundation/go-u2u/common/math"
	"github.com/unicornultrafoundation/go-u2u/core/state"
	"github.com/unicornultrafoundation/go-u2u/core/types"
	"github.com/unicornultrafoundation/go-u2u/core/vm"
	"github.com/unicornultrafoundation/go-u2u/crypto"
	"github.com/unicornultrafoundation/go-u2u/eth/tracers"
	"github.com/unicornultrafoundation/go-u2u/evmcore"
	"github.com/unicornultrafoundation/go-u2u/gossip/gasprice"
	"github.com/unicornultrafoundation/go-u2u/log"
	"github.com/unicornultrafoundation/go-u2u/p2p"
	"github.com/unicornultrafoundation/go-u2u/params"
	"github.com/unicornultrafoundation/go-u2u/rlp"
	"github.com/unicornultrafoundation/go-u2u/rpc"
	"github.com/unicornultrafoundation/go-u2u/trie"
	"github.com/unicornultrafoundation/go-u2u/u2u"
	"github.com/unicornultrafoundation/go-u2u/utils/adapters/ethdb2udb"
	"github.com/unicornultrafoundation/go-u2u/utils/dbutil/compactdb"
	"github.com/unicornultrafoundation/go-u2u/utils/signers/gsignercache"
	"github.com/unicornultrafoundation/go-u2u/utils/signers/internaltx"
)

const (
	// defaultTraceTimeout is the amount of time a single transaction can execute
	// by default before being forcefully aborted.
	defaultTraceTimeout = 5 * time.Second

	// defaultTraceReexec is the number of blocks the tracer is willing to go back
	// and reexecute to produce missing historical state necessary to run a specific
	// trace.
	defaultTraceReexec = uint64(128)
)

var (
	noUncles = []evmcore.EvmHeader{}
)

// PublicEthereumAPI provides an API to access Ethereum related information.
// It offers only methods that operate on public data that is freely available to anyone.
type PublicEthereumAPI struct {
	b Backend
}

// NewPublicEthereumAPI creates a new Ethereum protocol API.
func NewPublicEthereumAPI(b Backend) *PublicEthereumAPI {
	return &PublicEthereumAPI{b}
}

// GasPrice returns a suggestion for a gas price for legacy transactions.
func (s *PublicEthereumAPI) GasPrice(ctx context.Context) (*hexutil.Big, error) {
	tipcap := s.b.SuggestGasTipCap(ctx, gasprice.AsDefaultCertainty)
	tipcap.Add(tipcap, s.b.MinGasPrice())
	return (*hexutil.Big)(tipcap), nil
}

// MaxPriorityFeePerGas returns a suggestion for a gas tip cap for dynamic fee transactions.
func (s *PublicEthereumAPI) MaxPriorityFeePerGas(ctx context.Context) (*hexutil.Big, error) {
	tipcap := s.b.SuggestGasTipCap(ctx, gasprice.AsDefaultCertainty)
	return (*hexutil.Big)(tipcap), nil
}

type feeHistoryResult struct {
	OldestBlock  *hexutil.Big     `json:"oldestBlock"`
	Reward       [][]*hexutil.Big `json:"reward,omitempty"`
	BaseFee      []*hexutil.Big   `json:"baseFeePerGas,omitempty"`
	GasUsedRatio []float64        `json:"gasUsedRatio"`
	Note         string           `json:"note"`
}

var errInvalidPercentile = errors.New("invalid reward percentile")

func (s *PublicEthereumAPI) FeeHistory(ctx context.Context, blockCount rpc.DecimalOrHex, lastBlock rpc.BlockNumber, rewardPercentiles []float64) (*feeHistoryResult, error) {
	res := &feeHistoryResult{}
	res.Reward = make([][]*hexutil.Big, 0, blockCount)
	res.BaseFee = make([]*hexutil.Big, 0, blockCount)
	res.GasUsedRatio = make([]float64, 0, blockCount)
	res.OldestBlock = (*hexutil.Big)(new(big.Int))

	// validate input parameters
	if blockCount == 0 {
		return res, nil
	}
	if blockCount > 1024 {
		blockCount = 1024
	}
	for i, p := range rewardPercentiles {
		if p < 0 || p > 100 {
			return nil, fmt.Errorf("%w: %f", errInvalidPercentile, p)
		}
		if i > 0 && p < rewardPercentiles[i-1] {
			return nil, fmt.Errorf("%w: #%d:%f > #%d:%f", errInvalidPercentile, i-1, rewardPercentiles[i-1], i, p)
		}
	}
	last, err := s.b.ResolveRpcBlockNumberOrHash(ctx, rpc.BlockNumberOrHash{BlockNumber: &lastBlock})
	if err != nil {
		return nil, err
	}
	oldest := last
	if oldest > idx.Block(blockCount) {
		oldest -= idx.Block(blockCount - 1)
	} else {
		oldest = 0
	}

	baseFee := s.b.MinGasPrice()

	tips := make([]*big.Int, 0, len(rewardPercentiles))
	for _, p := range rewardPercentiles {
		tip := s.b.SuggestGasTipCap(ctx, uint64(gasprice.DecimalUnit*p/100.0))
		tips = append(tips, tip)
	}
	res.OldestBlock.ToInt().SetUint64(uint64(oldest))
	for i := uint64(0); i < uint64(last-oldest+1); i++ {
		// randomize the output to mimic the ETH API eth_feeHistory for compatibility reasons
		rTips := make([]*hexutil.Big, 0, len(tips))
		for _, t := range tips {
			rTip := t
			// don't randomize last iteration
			if i < uint64(last-oldest) {
				// increase by up to 2% randomly
				rTip = new(big.Int).Mul(t, big.NewInt(int64(rand.Intn(gasprice.DecimalUnit/50)+gasprice.DecimalUnit)))
				rTip.Div(rTip, big.NewInt(gasprice.DecimalUnit))
			}
			rTips = append(rTips, (*hexutil.Big)(rTip))
		}
		res.Reward = append(res.Reward, rTips)
		res.BaseFee = append(res.BaseFee, (*hexutil.Big)(baseFee))
		r := rand.New(rand.NewSource(int64(oldest) + int64(i)))
		res.GasUsedRatio = append(res.GasUsedRatio, 0.9+r.Float64()*0.1)
	}
	res.Note = `In the U2U network, the eth_feeHistory method operates slightly differently due to the network's unique consensus mechanism. ` +
		`Here, instead of returning a range of gas tip values from requested blocks, ` +
		`it provides a singular estimated gas tip based on a defined confidence level (indicated by the percentile parameter). ` +
		`This approach means that while you will receive replicated (and randomized) reward values across the requested blocks, ` +
		`the average or median of these values remains consistent with the intended gas tip.`
	return res, nil
}

func (s *PublicEthereumAPI) EffectiveBaseFee(ctx context.Context) *hexutil.Big {
	return (*hexutil.Big)(s.b.EffectiveMinGasPrice(ctx))
}

// Syncing returns true if node is syncing
func (s *PublicEthereumAPI) Syncing() (interface{}, error) {
	progress := s.b.Progress()
	// Return not syncing if the synchronisation already completed
	if time.Since(progress.CurrentBlockTime.Time()) <= 90*time.Minute { // should be >> MaxEmitInterval
		return false, nil
	}
	// Otherwise gather the block sync stats
	return map[string]interface{}{
		"startingBlock":    hexutil.Uint64(0), // back-compatibility
		"currentEpoch":     hexutil.Uint64(progress.CurrentEpoch),
		"currentBlock":     hexutil.Uint64(progress.CurrentBlock),
		"currentBlockHash": progress.CurrentBlockHash.Hex(),
		"currentBlockTime": hexutil.Uint64(progress.CurrentBlockTime),
		"highestBlock":     hexutil.Uint64(progress.HighestBlock),
		"highestEpoch":     hexutil.Uint64(progress.HighestEpoch),
		"pulledStates":     hexutil.Uint64(0), // back-compatibility
		"knownStates":      hexutil.Uint64(0), // back-compatibility
	}, nil
}

// PublicTxPoolAPI offers and API for the transaction pool. It only operates on data that is non confidential.
type PublicTxPoolAPI struct {
	b Backend
}

// NewPublicTxPoolAPI creates a new tx pool service that gives information about the transaction pool.
func NewPublicTxPoolAPI(b Backend) *PublicTxPoolAPI {
	return &PublicTxPoolAPI{b}
}

// Content returns the transactions contained within the transaction pool.
func (s *PublicTxPoolAPI) Content() map[string]map[string]map[string]*RPCTransaction {
	content := map[string]map[string]map[string]*RPCTransaction{
		"pending": make(map[string]map[string]*RPCTransaction),
		"queued":  make(map[string]map[string]*RPCTransaction),
	}
	pending, queue := s.b.TxPoolContent()

	curHeader := s.b.CurrentBlock().Header()
	// Flatten the pending transactions
	for account, txs := range pending {
		dump := make(map[string]*RPCTransaction)
		for _, tx := range txs {
			dump[fmt.Sprintf("%d", tx.Nonce())] = newRPCPendingTransaction(tx, curHeader.BaseFee)
		}
		content["pending"][account.Hex()] = dump
	}
	// Flatten the queued transactions
	for account, txs := range queue {
		dump := make(map[string]*RPCTransaction)
		for _, tx := range txs {
			dump[fmt.Sprintf("%d", tx.Nonce())] = newRPCPendingTransaction(tx, curHeader.BaseFee)
		}
		content["queued"][account.Hex()] = dump
	}
	return content
}

// ContentFrom returns the transactions contained within the transaction pool.
func (s *PublicTxPoolAPI) ContentFrom(addr common.Address) map[string]map[string]*RPCTransaction {
	content := make(map[string]map[string]*RPCTransaction, 2)
	pending, queue := s.b.TxPoolContentFrom(addr)
	curHeader := s.b.CurrentBlock().Header()

	// Build the pending transactions
	dump := make(map[string]*RPCTransaction, len(pending))
	for _, tx := range pending {
		dump[fmt.Sprintf("%d", tx.Nonce())] = newRPCPendingTransaction(tx, curHeader.BaseFee)
	}
	content["pending"] = dump

	// Build the queued transactions
	dump = make(map[string]*RPCTransaction, len(queue))
	for _, tx := range queue {
		dump[fmt.Sprintf("%d", tx.Nonce())] = newRPCPendingTransaction(tx, curHeader.BaseFee)
	}
	content["queued"] = dump

	return content
}

// Status returns the number of pending and queued transaction in the pool.
func (s *PublicTxPoolAPI) Status() map[string]hexutil.Uint {
	pending, queue := s.b.Stats()
	return map[string]hexutil.Uint{
		"pending": hexutil.Uint(pending),
		"queued":  hexutil.Uint(queue),
	}
}

// Inspect retrieves the content of the transaction pool and flattens it into an
// easily inspectable list.
func (s *PublicTxPoolAPI) Inspect() map[string]map[string]map[string]string {
	content := map[string]map[string]map[string]string{
		"pending": make(map[string]map[string]string),
		"queued":  make(map[string]map[string]string),
	}
	pending, queue := s.b.TxPoolContent()

	// Define a formatter to flatten a transaction into a string
	var format = func(tx *types.Transaction) string {
		if to := tx.To(); to != nil {
			return fmt.Sprintf("%s: %v wei + %v gas × %v wei", tx.To().Hex(), tx.Value(), tx.Gas(), tx.GasPrice())
		}
		return fmt.Sprintf("contract creation: %v wei + %v gas × %v wei", tx.Value(), tx.Gas(), tx.GasPrice())
	}
	// Flatten the pending transactions
	for account, txs := range pending {
		dump := make(map[string]string)
		for _, tx := range txs {
			dump[fmt.Sprintf("%d", tx.Nonce())] = format(tx)
		}
		content["pending"][account.Hex()] = dump
	}
	// Flatten the queued transactions
	for account, txs := range queue {
		dump := make(map[string]string)
		for _, tx := range txs {
			dump[fmt.Sprintf("%d", tx.Nonce())] = format(tx)
		}
		content["queued"][account.Hex()] = dump
	}
	return content
}

// PublicAccountAPI provides an API to access accounts managed by this node.
// It offers only methods that can retrieve accounts.
type PublicAccountAPI struct {
	am *accounts.Manager
}

// NewPublicAccountAPI creates a new PublicAccountAPI.
func NewPublicAccountAPI(am *accounts.Manager) *PublicAccountAPI {
	return &PublicAccountAPI{am: am}
}

// Accounts returns the collection of accounts this node manages
func (s *PublicAccountAPI) Accounts() []common.Address {
	return s.am.Accounts()
}

// PrivateAccountAPI provides an API to access accounts managed by this node.
// It offers methods to create, (un)lock en list accounts. Some methods accept
// passwords and are therefore considered private by default.
type PrivateAccountAPI struct {
	am        *accounts.Manager
	nonceLock *AddrLocker
	b         Backend
}

// NewPrivateAccountAPI create a new PrivateAccountAPI.
func NewPrivateAccountAPI(b Backend, nonceLock *AddrLocker) *PrivateAccountAPI {
	return &PrivateAccountAPI{
		am:        b.AccountManager(),
		nonceLock: nonceLock,
		b:         b,
	}
}

// ListAccounts will return a list of addresses for accounts this node manages.
func (s *PrivateAccountAPI) ListAccounts() []common.Address {
	return s.am.Accounts()
}

// RawWallet is a JSON representation of an accounts.Wallet interface, with its
// data contents extracted into plain fields.
type RawWallet struct {
	URL      string             `json:"url"`
	Status   string             `json:"status"`
	Failure  string             `json:"failure,omitempty"`
	Accounts []accounts.Account `json:"accounts,omitempty"`
}

// ListWallets will return a list of wallets this node manages.
func (s *PrivateAccountAPI) ListWallets() []RawWallet {
	wallets := make([]RawWallet, 0) // return [] instead of nil if empty
	for _, wallet := range s.am.Wallets() {
		status, failure := wallet.Status()

		raw := RawWallet{
			URL:      wallet.URL().String(),
			Status:   status,
			Accounts: wallet.Accounts(),
		}
		if failure != nil {
			raw.Failure = failure.Error()
		}
		wallets = append(wallets, raw)
	}
	return wallets
}

// OpenWallet initiates a hardware wallet opening procedure, establishing a USB
// connection and attempting to authenticate via the provided passphrase. Note,
// the method may return an extra challenge requiring a second open (e.g. the
// Trezor PIN matrix challenge).
func (s *PrivateAccountAPI) OpenWallet(url string, passphrase *string) error {
	wallet, err := s.am.Wallet(url)
	if err != nil {
		return err
	}
	pass := ""
	if passphrase != nil {
		pass = *passphrase
	}
	return wallet.Open(pass)
}

// DeriveAccount requests a HD wallet to derive a new account, optionally pinning
// it for later reuse.
func (s *PrivateAccountAPI) DeriveAccount(url string, path string, pin *bool) (accounts.Account, error) {
	wallet, err := s.am.Wallet(url)
	if err != nil {
		return accounts.Account{}, err
	}
	derivPath, err := accounts.ParseDerivationPath(path)
	if err != nil {
		return accounts.Account{}, err
	}
	if pin == nil {
		pin = new(bool)
	}
	return wallet.Derive(derivPath, *pin)
}

// NewAccount will create a new account and returns the address for the new account.
func (s *PrivateAccountAPI) NewAccount(password string) (common.Address, error) {
	ks, err := fetchKeystore(s.am)
	if err != nil {
		return common.Address{}, err
	}
	acc, err := ks.NewAccount(password)
	if err == nil {
		log.Info("Your new key was generated", "address", acc.Address)
		log.Warn("Please backup your key file!", "path", acc.URL.Path)
		log.Warn("Please remember your password!")
		return acc.Address, nil
	}
	return common.Address{}, err
}

// fetchKeystore retrieves the encrypted keystore from the account manager.
func fetchKeystore(am *accounts.Manager) (*keystore.KeyStore, error) {
	if ks := am.Backends(keystore.KeyStoreType); len(ks) > 0 {
		return ks[0].(*keystore.KeyStore), nil
	}
	return nil, errors.New("local keystore not used")
}

// ImportRawKey stores the given hex encoded ECDSA key into the key directory,
// encrypting it with the passphrase.
func (s *PrivateAccountAPI) ImportRawKey(privkey string, password string) (common.Address, error) {
	key, err := crypto.HexToECDSA(privkey)
	if err != nil {
		return common.Address{}, err
	}
	ks, err := fetchKeystore(s.am)
	if err != nil {
		return common.Address{}, err
	}
	acc, err := ks.ImportECDSA(key, password)
	return acc.Address, err
}

// UnlockAccount will unlock the account associated with the given address with
// the given password for duration seconds. If duration is nil it will use a
// default of 300 seconds. It returns an indication if the account was unlocked.
func (s *PrivateAccountAPI) UnlockAccount(ctx context.Context, addr common.Address, password string, duration *uint64) (bool, error) {
	// When the API is exposed by external RPC(http, ws etc), unless the user
	// explicitly specifies to allow the insecure account unlocking, otherwise
	// it is disabled.
	if s.b.ExtRPCEnabled() && !s.b.AccountManager().Config().InsecureUnlockAllowed {
		return false, errors.New("account unlock with HTTP access is forbidden")
	}

	const max = uint64(time.Duration(math.MaxInt64) / time.Second)
	var d time.Duration
	if duration == nil {
		d = 300 * time.Second
	} else if *duration > max {
		return false, errors.New("unlock duration too large")
	} else {
		d = time.Duration(*duration) * time.Second
	}
	ks, err := fetchKeystore(s.am)
	if err != nil {
		return false, err
	}
	err = ks.TimedUnlock(accounts.Account{Address: addr}, password, d)
	if err != nil {
		log.Warn("Failed account unlock attempt", "address", addr, "err", err)
	}
	return err == nil, err
}

// LockAccount will lock the account associated with the given address when it's unlocked.
func (s *PrivateAccountAPI) LockAccount(addr common.Address) bool {
	if ks, err := fetchKeystore(s.am); err == nil {
		return ks.Lock(addr) == nil
	}
	return false
}

// signTransaction sets defaults and signs the given transaction
// NOTE: the caller needs to ensure that the nonceLock is held, if applicable,
// and release it after the transaction has been submitted to the tx pool
func (s *PrivateAccountAPI) signTransaction(ctx context.Context, args *TransactionArgs, passwd string) (*types.Transaction, error) {
	// Look up the wallet containing the requested signer
	account := accounts.Account{Address: args.from()}
	wallet, err := s.am.Find(account)
	if err != nil {
		return nil, err
	}
	// Set some sanity defaults and terminate on failure
	if err := args.setDefaults(ctx, s.b); err != nil {
		return nil, err
	}
	// Assemble the transaction and sign with the wallet
	tx := args.toTransaction()

	return wallet.SignTxWithPassphrase(account, passwd, tx, s.b.ChainConfig().ChainID)
}

// SendTransaction will create a transaction from the given arguments and
// tries to sign it with the key associated with args.From. If the given
// passwd isn't able to decrypt the key it fails.
func (s *PrivateAccountAPI) SendTransaction(ctx context.Context, args TransactionArgs, passwd string) (common.Hash, error) {
	if args.Nonce == nil {
		// Hold the addresse's mutex around signing to prevent concurrent assignment of
		// the same nonce to multiple accounts.
		s.nonceLock.LockAddr(args.from())
		defer s.nonceLock.UnlockAddr(args.from())
	}
	signed, err := s.signTransaction(ctx, &args, passwd)
	if err != nil {
		log.Warn("Failed transaction send attempt", "from", args.from(), "to", args.To, "value", args.Value.ToInt(), "err", err)
		return common.Hash{}, err
	}
	return SubmitTransaction(ctx, s.b, signed)
}

// SignTransaction will create a transaction from the given arguments and
// tries to sign it with the key associated with args.From. If the given passwd isn't
// able to decrypt the key it fails. The transaction is returned in RLP-form, not broadcast
// to other nodes
func (s *PrivateAccountAPI) SignTransaction(ctx context.Context, args TransactionArgs, passwd string) (*SignTransactionResult, error) {
	// No need to obtain the noncelock mutex, since we won't be sending this
	// tx into the transaction pool, but right back to the user
	if args.From == nil {
		return nil, fmt.Errorf("sender not specified")
	}
	if args.Gas == nil {
		return nil, fmt.Errorf("gas not specified")
	}
	if args.GasPrice == nil && (args.MaxFeePerGas == nil || args.MaxPriorityFeePerGas == nil) {
		return nil, fmt.Errorf("missing gasPrice or maxFeePerGas/maxPriorityFeePerGas")
	}
	if args.Nonce == nil {
		return nil, fmt.Errorf("nonce not specified")
	}
	// Before actually signing the transaction, ensure the transaction fee is reasonable.
	tx := args.toTransaction()
	if err := checkTxFee(tx.GasPrice(), tx.Gas(), s.b.RPCTxFeeCap()); err != nil {
		return nil, err
	}
	signed, err := s.signTransaction(ctx, &args, passwd)
	if err != nil {
		log.Warn("Failed transaction sign attempt", "from", args.from(), "to", args.To, "value", args.Value.ToInt(), "err", err)
		return nil, err
	}
	data, err := signed.MarshalBinary()
	if err != nil {
		return nil, err
	}
	return &SignTransactionResult{data, signed}, nil
}

// Sign calculates an Ethereum ECDSA signature for:
// keccack256("\x19Ethereum Signed Message:\n" + len(message) + message))
//
// Note, the produced signature conforms to the secp256k1 curve R, S and V values,
// where the V value will be 27 or 28 for legacy reasons.
//
// The key used to calculate the signature is decrypted with the given password.
//
// https://github.com/ethereum/go-ethereum/wiki/Management-APIs#personal_sign
func (s *PrivateAccountAPI) Sign(ctx context.Context, data hexutil.Bytes, addr common.Address, passwd string) (hexutil.Bytes, error) {
	// Look up the wallet containing the requested signer
	account := accounts.Account{Address: addr}

	wallet, err := s.b.AccountManager().Find(account)
	if err != nil {
		return nil, err
	}
	// Assemble sign the data with the wallet
	signature, err := wallet.SignTextWithPassphrase(account, passwd, data)
	if err != nil {
		log.Warn("Failed data sign attempt", "address", addr, "err", err)
		return nil, err
	}
	signature[crypto.RecoveryIDOffset] += 27 // Transform V from 0/1 to 27/28 according to the yellow paper
	return signature, nil
}

// EcRecover returns the address for the account that was used to create the signature.
// Note, this function is compatible with eth_sign and personal_sign. As such it recovers
// the address of:
// hash = keccak256("\x19Ethereum Signed Message:\n"${message length}${message})
// addr = ecrecover(hash, signature)
//
// Note, the signature must conform to the secp256k1 curve R, S and V values, where
// the V value must be 27 or 28 for legacy reasons.
//
// https://github.com/ethereum/go-ethereum/wiki/Management-APIs#personal_ecRecover
func (s *PrivateAccountAPI) EcRecover(ctx context.Context, data, sig hexutil.Bytes) (common.Address, error) {
	if len(sig) != crypto.SignatureLength {
		return common.Address{}, fmt.Errorf("signature must be %d bytes long", crypto.SignatureLength)
	}
	if sig[crypto.RecoveryIDOffset] != 27 && sig[crypto.RecoveryIDOffset] != 28 {
		return common.Address{}, fmt.Errorf("invalid Ethereum signature (V is not 27 or 28)")
	}
	sig[crypto.RecoveryIDOffset] -= 27 // Transform yellow paper V from 27/28 to 0/1

	rpk, err := crypto.SigToPub(accounts.TextHash(data), sig)
	if err != nil {
		return common.Address{}, err
	}
	return crypto.PubkeyToAddress(*rpk), nil
}

// SignAndSendTransaction was renamed to SendTransaction. This method is deprecated
// and will be removed in the future. It primary goal is to give clients time to update.
func (s *PrivateAccountAPI) SignAndSendTransaction(ctx context.Context, args TransactionArgs, passwd string) (common.Hash, error) {
	return s.SendTransaction(ctx, args, passwd)
}

// InitializeWallet initializes a new wallet at the provided URL, by generating and returning a new private key.
func (s *PrivateAccountAPI) InitializeWallet(ctx context.Context, url string) (string, error) {
	wallet, err := s.am.Wallet(url)
	if err != nil {
		return "", err
	}

	entropy, err := bip39.NewEntropy(256)
	if err != nil {
		return "", err
	}

	mnemonic, err := bip39.NewMnemonic(entropy)
	if err != nil {
		return "", err
	}

	seed := bip39.NewSeed(mnemonic, "")

	switch wallet := wallet.(type) {
	case *scwallet.Wallet:
		return mnemonic, wallet.Initialize(seed)
	default:
		return "", fmt.Errorf("specified wallet does not support initialization")
	}
}

// Unpair deletes a pairing between wallet and geth.
func (s *PrivateAccountAPI) Unpair(ctx context.Context, url string, pin string) error {
	wallet, err := s.am.Wallet(url)
	if err != nil {
		return err
	}

	switch wallet := wallet.(type) {
	case *scwallet.Wallet:
		return wallet.Unpair([]byte(pin))
	default:
		return fmt.Errorf("specified wallet does not support pairing")
	}
}

// PublicBlockChainAPI provides an API to access the Ethereum blockchain.
// It offers only methods that operate on public data that is freely available to anyone.
type PublicBlockChainAPI struct {
	b Backend
}

// NewPublicBlockChainAPI creates a new Ethereum blockchain API.
func NewPublicBlockChainAPI(b Backend) *PublicBlockChainAPI {
	return &PublicBlockChainAPI{b}
}

// CurrentEpoch returns current epoch number.
func (s *PublicBlockChainAPI) CurrentEpoch(ctx context.Context) hexutil.Uint64 {
	return hexutil.Uint64(s.b.CurrentEpoch(ctx))
}

// GetRules returns network rules for an epoch
func (s *PublicBlockChainAPI) GetRules(ctx context.Context, epoch rpc.BlockNumber) (*u2u.Rules, error) {
	_, es, err := s.b.GetEpochBlockState(ctx, epoch)
	if err != nil {
		return nil, err
	}
	if es == nil {
		return nil, nil
	}
	return &es.Rules, nil
}

// GetEpochBlock returns block height in a beginning of an epoch
func (s *PublicBlockChainAPI) GetEpochBlock(ctx context.Context, epoch rpc.BlockNumber) (hexutil.Uint64, error) {
	bs, _, err := s.b.GetEpochBlockState(ctx, epoch)
	if err != nil {
		return 0, err
	}
	if bs == nil {
		return 0, nil
	}
	return hexutil.Uint64(bs.LastBlock.Idx), nil
}

// ChainId is the EIP-155 replay-protection chain id for the current ethereum chain config.
func (api *PublicBlockChainAPI) ChainId() (*hexutil.Big, error) {
	// if current block is at or past the EIP-155 replay-protection fork block, return chainID from config
	if config := api.b.ChainConfig(); config.IsEIP155(api.b.CurrentBlock().Number) {
		return (*hexutil.Big)(config.ChainID), nil
	}
	return nil, fmt.Errorf("chain not synced beyond EIP-155 replay-protection fork block")
}

// BlockNumber returns the block number of the chain head.
func (s *PublicBlockChainAPI) BlockNumber() hexutil.Uint64 {
	header, _ := s.b.HeaderByNumber(context.Background(), rpc.LatestBlockNumber) // latest header should always be available
	return hexutil.Uint64(header.Number.Uint64())
}

// GetBalance returns the amount of wei for the given address in the state of the
// given block number. The rpc.LatestBlockNumber and rpc.PendingBlockNumber meta
// block numbers are also allowed.
func (s *PublicBlockChainAPI) GetBalance(ctx context.Context, address common.Address, blockNrOrHash rpc.BlockNumberOrHash) (*hexutil.Big, error) {
	state, _, err := s.b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
	if state == nil || err != nil {
		return nil, err
	}
	return (*hexutil.Big)(state.GetBalance(address)), state.Error()
}

// AccountResult is result struct for GetProof
type AccountResult struct {
	Address      common.Address  `json:"address"`
	AccountProof []string        `json:"accountProof"`
	Balance      *hexutil.Big    `json:"balance"`
	CodeHash     common.Hash     `json:"codeHash"`
	Nonce        hexutil.Uint64  `json:"nonce"`
	StorageHash  common.Hash     `json:"storageHash"`
	StorageProof []StorageResult `json:"storageProof"`
}

// StorageResult is result struct for GetProof
type StorageResult struct {
	Key   string       `json:"key"`
	Value *hexutil.Big `json:"value"`
	Proof []string     `json:"proof"`
}

// GetProof returns the Merkle-proof for a given account and optionally some storage keys.
func (s *PublicBlockChainAPI) GetProof(ctx context.Context, address common.Address, storageKeys []string, blockNrOrHash rpc.BlockNumberOrHash) (*AccountResult, error) {
	state, _, err := s.b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
	if state == nil || err != nil {
		return nil, err
	}

	storageTrie := state.StorageTrie(address)
	storageHash := types.EmptyRootHash
	codeHash := state.GetCodeHash(address)
	storageProof := make([]StorageResult, len(storageKeys))

	// if we have a storageTrie, (which means the account exists), we can update the storagehash
	if storageTrie != nil {
		storageHash = storageTrie.Hash()
	} else {
		// no storageTrie means the account does not exist, so the codeHash is the hash of an empty bytearray.
		codeHash = crypto.Keccak256Hash(nil)
	}

	// create the proof for the storageKeys
	for i, key := range storageKeys {
		if storageTrie != nil {
			proof, storageError := state.GetStorageProof(address, common.HexToHash(key))
			if storageError != nil {
				return nil, storageError
			}
			storageProof[i] = StorageResult{key, (*hexutil.Big)(state.GetState(address, common.HexToHash(key)).Big()), toHexSlice(proof)}
		} else {
			storageProof[i] = StorageResult{key, &hexutil.Big{}, []string{}}
		}
	}

	// create the accountProof
	accountProof, proofErr := state.GetProof(address)
	if proofErr != nil {
		return nil, proofErr
	}

	return &AccountResult{
		Address:      address,
		AccountProof: toHexSlice(accountProof),
		Balance:      (*hexutil.Big)(state.GetBalance(address)),
		CodeHash:     codeHash,
		Nonce:        hexutil.Uint64(state.GetNonce(address)),
		StorageHash:  storageHash,
		StorageProof: storageProof,
	}, state.Error()
}

// GetHeaderByNumber returns the requested canonical block header.
// * When blockNr is -1 the chain head is returned.
// * When blockNr is -2 the pending chain head is returned.
func (s *PublicBlockChainAPI) GetHeaderByNumber(ctx context.Context, number rpc.BlockNumber) (map[string]interface{}, error) {
	header, err := s.b.HeaderByNumber(ctx, number)
	if header != nil && err == nil {
		response := s.rpcMarshalHeader(header, s.calculateExtBlockApi(ctx, number))
		if number == rpc.PendingBlockNumber {
			// Pending header need to nil out a few fields
			for _, field := range []string{"hash", "nonce", "miner"} {
				response[field] = nil
			}
		}
		return response, err
	}
	return nil, err
}

// GetHeaderByHash returns the requested header by hash.
func (s *PublicBlockChainAPI) GetHeaderByHash(ctx context.Context, hash common.Hash) map[string]interface{} {
	header, _ := s.b.HeaderByHash(ctx, hash)
	if header != nil {
		return s.rpcMarshalHeader(header, s.calculateExtBlockApi(ctx, rpc.BlockNumber(header.Number.Uint64())))
	}
	return nil
}

func (s *PublicBlockChainAPI) calculateExtBlockApi(ctx context.Context, blkNumber rpc.BlockNumber) extBlockApi {
	var ext extBlockApi
	if s.b.CalcBlockExtApi() && blkNumber != rpc.EarliestBlockNumber {
		receipts, err := s.b.GetReceiptsByNumber(ctx, blkNumber)
		if err != nil {
			return ext
		}
		if receipts.Len() != 0 {
			ext.receiptsRoot = types.DeriveSha(receipts, trie.NewStackTrie(nil))
			ext.bloom = types.CreateBloom(receipts)
		} else {
			ext.receiptsRoot = types.EmptyRootHash
		}
	}
	return ext
}

// GetBlockByNumber returns the requested canonical block.
//   - When blockNr is -1 the chain head is returned.
//   - When blockNr is -2 the pending chain head is returned.
//   - When fullTx is true all transactions in the block are returned, otherwise
//     only the transaction hash is returned.
func (s *PublicBlockChainAPI) GetBlockByNumber(ctx context.Context, number rpc.BlockNumber, fullTx bool) (map[string]interface{}, error) {
	block, err := s.b.BlockByNumber(ctx, number)
	if block != nil && err == nil {
		response, err := s.rpcMarshalBlock(block, s.calculateExtBlockApi(ctx, number), true, fullTx)
		if err == nil && number == rpc.PendingBlockNumber {
			// Pending blocks need to nil out a few fields
			for _, field := range []string{"hash", "nonce", "miner"} {
				response[field] = nil
			}
		}
		return response, err
	}
	return nil, err
}

// GetBlockByHash returns the requested block. When fullTx is true all transactions in the block are returned in full
// detail, otherwise only the transaction hash is returned.
func (s *PublicBlockChainAPI) GetBlockByHash(ctx context.Context, hash common.Hash, fullTx bool) (map[string]interface{}, error) {
	block, err := s.b.BlockByHash(ctx, hash)
	if block != nil {
		return s.rpcMarshalBlock(block, s.calculateExtBlockApi(ctx, rpc.BlockNumber(block.NumberU64())), true, fullTx)
	}
	return nil, err
}

// GetUncleByBlockNumberAndIndex returns the uncle block for the given block hash and index. When fullTx is true
// all transactions in the block are returned in full detail, otherwise only the transaction hash is returned.
func (s *PublicBlockChainAPI) GetUncleByBlockNumberAndIndex(ctx context.Context, blockNr rpc.BlockNumber, index hexutil.Uint) (map[string]interface{}, error) {
	block, err := s.b.BlockByNumber(ctx, blockNr)
	if block != nil {
		log.Debug("Requested uncle not found", "number", blockNr, "hash", block.Hash, "index", index)
		return nil, nil
	}
	return nil, err
}

// GetUncleByBlockHashAndIndex returns the uncle block for the given block hash and index. When fullTx is true
// all transactions in the block are returned in full detail, otherwise only the transaction hash is returned.
func (s *PublicBlockChainAPI) GetUncleByBlockHashAndIndex(ctx context.Context, blockHash common.Hash, index hexutil.Uint) (map[string]interface{}, error) {
	block, err := s.b.BlockByHash(ctx, blockHash)
	if block != nil {
		log.Debug("Requested uncle not found", "number", block.Number, "hash", blockHash, "index", index)
		return nil, nil
	}
	return nil, err
}

// GetUncleCountByBlockNumber returns number of uncles in the block for the given block number
func (s *PublicBlockChainAPI) GetUncleCountByBlockNumber(ctx context.Context, blockNr rpc.BlockNumber) *hexutil.Uint {
	if block, _ := s.b.BlockByNumber(ctx, blockNr); block != nil {
		n := hexutil.Uint(len(noUncles))
		return &n
	}
	return nil
}

// GetUncleCountByBlockHash returns number of uncles in the block for the given block hash
func (s *PublicBlockChainAPI) GetUncleCountByBlockHash(ctx context.Context, blockHash common.Hash) *hexutil.Uint {
	if block, _ := s.b.BlockByHash(ctx, blockHash); block != nil {
		n := hexutil.Uint(len(noUncles))
		return &n
	}
	return nil
}

// GetCode returns the code stored at the given address in the state for the given block number.
func (s *PublicBlockChainAPI) GetCode(ctx context.Context, address common.Address, blockNrOrHash rpc.BlockNumberOrHash) (hexutil.Bytes, error) {
	state, _, err := s.b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
	if state == nil || err != nil {
		return nil, err
	}
	code := state.GetCode(address)
	return code, state.Error()
}

// GetStorageAt returns the storage from the state at the given address, key and
// block number. The rpc.LatestBlockNumber and rpc.PendingBlockNumber meta block
// numbers are also allowed.
func (s *PublicBlockChainAPI) GetStorageAt(ctx context.Context, address common.Address, key string, blockNr rpc.BlockNumberOrHash) (hexutil.Bytes, error) {
	state, _, err := s.b.StateAndHeaderByNumberOrHash(ctx, blockNr)
	if state == nil || err != nil {
		return nil, err
	}
	res := state.GetState(address, common.HexToHash(key))
	return res[:], state.Error()
}

// OverrideAccount indicates the overriding fields of account during the execution
// of a message call.
// Note, state and stateDiff can't be specified at the same time. If state is
// set, message execution will only use the data in the given state. Otherwise
// if statDiff is set, all diff will be applied first and then execute the call
// message.
type OverrideAccount struct {
	Nonce     *hexutil.Uint64              `json:"nonce"`
	Code      *hexutil.Bytes               `json:"code"`
	Balance   **hexutil.Big                `json:"balance"`
	State     *map[common.Hash]common.Hash `json:"state"`
	StateDiff *map[common.Hash]common.Hash `json:"stateDiff"`
}

// StateOverride is the collection of overridden accounts.
type StateOverride map[common.Address]OverrideAccount

// Apply overrides the fields of specified accounts into the given state.
func (diff *StateOverride) Apply(state *state.StateDB) error {
	if diff == nil {
		return nil
	}
	for addr, account := range *diff {
		// Override account nonce.
		if account.Nonce != nil {
			state.SetNonce(addr, uint64(*account.Nonce))
		}
		// Override account(contract) code.
		if account.Code != nil {
			state.SetCode(addr, *account.Code)
		}
		// Override account balance.
		if account.Balance != nil {
			state.SetBalance(addr, (*big.Int)(*account.Balance))
		}
		if account.State != nil && account.StateDiff != nil {
			return fmt.Errorf("account %s has both 'state' and 'stateDiff'", addr.Hex())
		}
		// Replace entire state if caller requires.
		if account.State != nil {
			state.SetStorage(addr, *account.State)
		}
		// Apply state diff into specified accounts.
		if account.StateDiff != nil {
			for key, value := range *account.StateDiff {
				state.SetState(addr, key, value)
			}
		}
	}
	return nil
}

// BlockOverrides is a set of header fields to override.
type BlockOverrides struct {
	Number     *hexutil.Big
	Difficulty *hexutil.Big
	Time       *hexutil.Uint64
	GasLimit   *hexutil.Uint64
	Coinbase   *common.Address
	Random     *common.Hash
	BaseFee    *hexutil.Big
}

// Apply overrides the given header fields into the given block context.
func (diff *BlockOverrides) Apply(blockCtx *vm.BlockContext) {
	if diff == nil {
		return
	}
	if diff.Number != nil {
		blockCtx.BlockNumber = diff.Number.ToInt()
	}
	if diff.Difficulty != nil {
		blockCtx.Difficulty = diff.Difficulty.ToInt()
	}
	if diff.Time != nil {
		blockCtx.Time = big.NewInt(int64(*diff.Time))
	}
	if diff.GasLimit != nil {
		blockCtx.GasLimit = uint64(*diff.GasLimit)
	}
	if diff.Coinbase != nil {
		blockCtx.Coinbase = *diff.Coinbase
	}
	if diff.BaseFee != nil {
		blockCtx.BaseFee = diff.BaseFee.ToInt()
	}
}

// ChainContextBackend provides methods required to implement ChainContext.
type ChainContextBackend interface {
	HeaderByNumber(context.Context, rpc.BlockNumber) (*evmcore.EvmHeader, error)
}

// ChainContext is an implementation of core.ChainContext. It's main use-case
// is instantiating a vm.BlockContext without having access to the BlockChain object.
type ChainContext struct {
	b   ChainContextBackend
	ctx context.Context
}

// NewChainContext creates a new ChainContext object.
func NewChainContext(ctx context.Context, backend ChainContextBackend) *ChainContext {
	return &ChainContext{ctx: ctx, b: backend}
}

func (context *ChainContext) GetHeader(hash common.Hash, number uint64) *evmcore.EvmHeader {
	// This method is called to get the hash for a block number when executing the BLOCKHASH
	// opcode. Hence no need to search for non-canonical blocks.
	header, err := context.b.HeaderByNumber(context.ctx, rpc.BlockNumber(number))
	if err != nil || header.Hash != hash {
		return nil
	}
	return header
}

func DoCall(ctx context.Context, b Backend, args TransactionArgs, blockNrOrHash rpc.BlockNumberOrHash, overrides *StateOverride, timeout time.Duration, globalGasCap uint64) (*evmcore.ExecutionResult, error) {
	defer func(start time.Time) { log.Debug("Executing EVM call finished", "runtime", time.Since(start)) }(time.Now())

	state, header, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
	if state == nil || err != nil {
		return nil, err
	}
	if err := overrides.Apply(state); err != nil {
		return nil, err
	}
	// Setup context so it may be cancelled the call has completed
	// or, in case of unmetered gas, setup a context with a timeout.
	var cancel context.CancelFunc
	if timeout > 0 {
		ctx, cancel = context.WithTimeout(ctx, timeout)
	} else {
		ctx, cancel = context.WithCancel(ctx)
	}
	// Make sure the context is cancelled when the call has completed
	// this makes sure resources are cleaned up.
	defer cancel()

	// Get a new instance of the EVM.
	msg, err := args.ToMessage(globalGasCap, header.BaseFee)
	if err != nil {
		return nil, err
	}
	vmConfig := u2u.DefaultVMConfig
	vmConfig.NoBaseFee = true
	evm, vmError, err := b.GetEVM(ctx, msg, state, header, &vmConfig)
	if err != nil {
		return nil, err
	}
	// Wait for the context to be done and cancel the evm. Even if the
	// EVM has finished, cancelling may be done (repeatedly)
	go func() {
		<-ctx.Done()
		evm.Cancel()
	}()

	// Execute the message.
	gp := new(evmcore.GasPool).AddGas(math.MaxUint64)
	result, err := evmcore.ApplyMessage(evm, msg, gp)
	if err := vmError(); err != nil {
		return nil, err
	}

	// If the timer caused an abort, return an appropriate error message
	if evm.Cancelled() {
		return nil, fmt.Errorf("execution aborted (timeout = %v)", timeout)
	}
	if err != nil {
		return result, fmt.Errorf("err: %w (supplied gas %d)", err, msg.Gas())
	}
	return result, nil
}

func newRevertError(result *evmcore.ExecutionResult) *revertError {
	reason, errUnpack := abi.UnpackRevert(result.Revert())
	err := errors.New("execution reverted")
	if errUnpack == nil {
		err = fmt.Errorf("execution reverted: %v", reason)
	}
	return &revertError{
		error:  err,
		reason: hexutil.Encode(result.Revert()),
	}
}

// revertError is an API error that encompassas an EVM revertal with JSON error
// code and a binary data blob.
type revertError struct {
	error
	reason string // revert reason hex encoded
}

// ErrorCode returns the JSON error code for a revertal.
// See: https://github.com/ethereum/wiki/wiki/JSON-RPC-Error-Codes-Improvement-Proposal
func (e *revertError) ErrorCode() int {
	return 3
}

// ErrorData returns the hex encoded revert reason.
func (e *revertError) ErrorData() interface{} {
	return e.reason
}

// Call executes the given transaction on the state for the given block number.
//
// Additionally, the caller can specify a batch of contract for fields overriding.
//
// Note, this function doesn't make and changes in the state/blockchain and is
// useful to execute and retrieve values.
func (s *PublicBlockChainAPI) Call(ctx context.Context, args TransactionArgs, blockNrOrHash rpc.BlockNumberOrHash, overrides *StateOverride) (hexutil.Bytes, error) {
	result, err := DoCall(ctx, s.b, args, blockNrOrHash, overrides, s.b.RPCTimeout(), s.b.RPCGasCap())
	if err != nil {
		return nil, err
	}
	// If the result contains a revert reason, try to unpack and return it.
	if len(result.Revert()) > 0 {
		return nil, newRevertError(result)
	}
	return result.Return(), result.Err
}

// DoEstimateGas - binary search the gas requirement, as it may be higher than the amount used
func DoEstimateGas(ctx context.Context, b Backend, args TransactionArgs, blockNrOrHash rpc.BlockNumberOrHash, gasCap uint64) (hexutil.Uint64, error) {
	// Binary search the gas requirement, as it may be higher than the amount used
	var (
		lo  uint64 = params.TxGas - 1
		hi  uint64
		cap uint64
	)
	// Use zero address if sender unspecified.
	if args.From == nil {
		args.From = new(common.Address)
	}
	// Determine the highest gas limit can be used during the estimation.
	if args.Gas != nil && uint64(*args.Gas) >= params.TxGas {
		hi = uint64(*args.Gas)
	} else {
		hi = b.MaxGasLimit()
	}
	// Normalize the max fee per gas the call is willing to spend.
	var feeCap *big.Int
	if args.GasPrice != nil && (args.MaxFeePerGas != nil || args.MaxPriorityFeePerGas != nil) {
		return 0, errors.New("both gasPrice and (maxFeePerGas or maxPriorityFeePerGas) specified")
	} else if args.GasPrice != nil {
		feeCap = args.GasPrice.ToInt()
	} else if args.MaxFeePerGas != nil {
		feeCap = args.MaxFeePerGas.ToInt()
	} else {
		feeCap = common.Big0
	}
	// Recap the highest gas limit with account's available balance.
	if feeCap.BitLen() != 0 {
		state, _, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
		if state == nil || err != nil {
			return 0, err
		}
		balance := state.GetBalance(*args.From) // from can't be nil
		available := new(big.Int).Set(balance)
		if args.Value != nil {
			if args.Value.ToInt().Cmp(available) >= 0 {
				return 0, errors.New("insufficient funds for transfer")
			}
			available.Sub(available, args.Value.ToInt())
		}
		allowance := new(big.Int).Div(available, feeCap)

		// If the allowance is larger than maximum uint64, skip checking
		if allowance.IsUint64() && hi > allowance.Uint64() {
			transfer := args.Value
			if transfer == nil {
				transfer = new(hexutil.Big)
			}
			log.Warn("Gas estimation capped by limited funds", "original", hi, "balance", balance,
				"sent", transfer.ToInt(), "maxFeePerGas", feeCap, "fundable", allowance)
			hi = allowance.Uint64()
		}
	}
	// Recap the highest gas allowance with specified gascap.
	if gasCap != 0 && hi > gasCap {
		log.Warn("Caller gas above allowance, capping", "requested", hi, "cap", gasCap)
		hi = gasCap
	}
	cap = hi

	// Create a helper to check if a gas allowance results in an executable transaction
	executable := func(gas uint64) (bool, *evmcore.ExecutionResult, error) {
		args.Gas = (*hexutil.Uint64)(&gas)

		result, err := DoCall(ctx, b, args, blockNrOrHash, nil, 0, gasCap)
		if err != nil {
			if errors.Is(err, evmcore.ErrIntrinsicGas) {
				return true, nil, nil // Special case, raise gas limit
			}
			return true, nil, err // Bail out
		}
		return result.Failed(), result, nil
	}
	// Execute the binary search and hone in on an executable gas limit
	for lo+1 < hi {
		mid := (hi + lo) / 2
		failed, _, err := executable(mid)

		// If the error is not nil(consensus error), it means the provided message
		// call or transaction will never be accepted no matter how much gas it is
		// assigned. Return the error directly, don't struggle any more.
		if err != nil {
			return 0, err
		}
		if failed {
			lo = mid
		} else {
			hi = mid
		}
	}
	// Reject the transaction as invalid if it still fails at the highest allowance
	if hi == cap {
		failed, result, err := executable(hi)
		if err != nil {
			return 0, err
		}
		if failed {
			if result != nil && result.Err != vm.ErrOutOfGas {
				if len(result.Revert()) > 0 {
					return 0, newRevertError(result)
				}
				return 0, result.Err
			}
			// Otherwise, the specified gas cap is too low
			return 0, fmt.Errorf("gas required exceeds allowance (%d)", cap)
		}
	}
	return hexutil.Uint64(hi), nil
}

// EstimateGas returns an estimate of the amount of gas needed to execute the
// given transaction against the current pending block.
func (s *PublicBlockChainAPI) EstimateGas(ctx context.Context, args TransactionArgs, blockNrOrHash *rpc.BlockNumberOrHash) (hexutil.Uint64, error) {
	bNrOrHash := rpc.BlockNumberOrHashWithNumber(rpc.LatestBlockNumber)
	if blockNrOrHash != nil {
		bNrOrHash = *blockNrOrHash
	}
	return DoEstimateGas(ctx, s.b, args, bNrOrHash, s.b.RPCGasCap())
}

// ExecutionResult groups all structured logs emitted by the EVM
// while replaying a transaction in debug mode as well as transaction
// execution status, the amount of gas used and the return value
type ExecutionResult struct {
	Gas         uint64         `json:"gas"`
	Failed      bool           `json:"failed"`
	ReturnValue string         `json:"returnValue"`
	StructLogs  []StructLogRes `json:"structLogs"`
}

// StructLogRes stores a structured log emitted by the EVM while replaying a
// transaction in debug mode
type StructLogRes struct {
	Pc      uint64             `json:"pc"`
	Op      string             `json:"op"`
	Gas     uint64             `json:"gas"`
	GasCost uint64             `json:"gasCost"`
	Depth   int                `json:"depth"`
	Error   string             `json:"error,omitempty"`
	Stack   *[]string          `json:"stack,omitempty"`
	Memory  *[]string          `json:"memory,omitempty"`
	Storage *map[string]string `json:"storage,omitempty"`
}

// FormatLogs formats EVM returned structured logs for json output
func FormatLogs(logs []vm.StructLog) []StructLogRes {
	formatted := make([]StructLogRes, len(logs))
	for index, trace := range logs {
		formatted[index] = StructLogRes{
			Pc:      trace.Pc,
			Op:      trace.Op.String(),
			Gas:     trace.Gas,
			GasCost: trace.GasCost,
			Depth:   trace.Depth,
			Error:   trace.ErrorString(),
		}
		if trace.Stack != nil {
			stack := make([]string, len(trace.Stack))
			for i, stackValue := range trace.Stack {
				stack[i] = stackValue.Hex()
			}
			formatted[index].Stack = &stack
		}
		if trace.Memory != nil {
			memory := make([]string, 0, (len(trace.Memory)+31)/32)
			for i := 0; i+32 <= len(trace.Memory); i += 32 {
				memory = append(memory, fmt.Sprintf("%x", trace.Memory[i:i+32]))
			}
			formatted[index].Memory = &memory
		}
		if trace.Storage != nil {
			storage := make(map[string]string)
			for i, storageValue := range trace.Storage {
				storage[fmt.Sprintf("%x", i)] = fmt.Sprintf("%x", storageValue)
			}
			formatted[index].Storage = &storage
		}
	}
	return formatted
}

type extBlockApi struct {
	bloom        types.Bloom
	receiptsRoot common.Hash
}

// RPCMarshalHeader converts the given header to the RPC output .
func RPCMarshalHeader(head *evmcore.EvmHeader, ext extBlockApi) map[string]interface{} {
	result := map[string]interface{}{
		"number":           (*hexutil.Big)(head.Number),
		"epoch":            hexutil.Uint64(hash.Event(head.Hash).Epoch()),
		"hash":             head.Hash, // store EvmBlock's hash in extra, because extra is always empty
		"parentHash":       head.ParentHash,
		"nonce":            types.BlockNonce{},
		"mixHash":          common.Hash{},
		"sha3Uncles":       types.EmptyUncleHash,
		"logsBloom":        ext.bloom,
		"stateRoot":        head.Root,
		"miner":            head.Coinbase,
		"difficulty":       (*hexutil.Big)(new(big.Int)),
		"extraData":        hexutil.Bytes([]byte{}),
		"size":             hexutil.Uint64(head.EthHeader().Size()),
		"gasLimit":         hexutil.Uint64(0xffffffffffff), // don't use too much bits here to avoid parsing issues
		"gasUsed":          hexutil.Uint64(head.GasUsed),
		"timestamp":        hexutil.Uint64(head.Time.Unix()),
		"timestampNano":    hexutil.Uint64(head.Time),
		"transactionsRoot": head.TxHash,
		"receiptsRoot":     ext.receiptsRoot,
	}
	if head.BaseFee != nil {
		result["baseFeePerGas"] = (*hexutil.Big)(head.BaseFee)
	}
	return result
}

// RPCMarshalBlock converts the given block to the RPC output which depends on fullTx. If inclTx is true transactions are
// returned. When fullTx is true the returned block contains full transaction details, otherwise it will only contain
// transaction hashes.
func RPCMarshalBlock(block *evmcore.EvmBlock, ext extBlockApi, inclTx bool, fullTx bool) (map[string]interface{}, error) {
	fields := RPCMarshalHeader(block.Header(), ext)
	fields["size"] = hexutil.Uint64(block.EthBlock().Size())

	if inclTx {
		formatTx := func(tx *types.Transaction) (interface{}, error) {
			return tx.Hash(), nil
		}
		if fullTx {
			formatTx = func(tx *types.Transaction) (interface{}, error) {
				return newRPCTransactionFromBlockHash(block, tx.Hash()), nil
			}
		}
		txs := block.Transactions
		transactions := make([]interface{}, len(txs))
		var err error
		for i, tx := range txs {
			if transactions[i], err = formatTx(tx); err != nil {
				return nil, err
			}
		}
		fields["transactions"] = transactions
	}
	uncles := noUncles
	uncleHashes := make([]common.Hash, len(uncles))
	for i, uncle := range uncles {
		uncleHashes[i] = uncle.Hash
	}
	fields["uncles"] = uncleHashes

	return fields, nil
}

// rpcMarshalHeader uses the generalized output filler, then adds the total difficulty field, which requires
// a `PublicBlockchainAPI`.
func (s *PublicBlockChainAPI) rpcMarshalHeader(header *evmcore.EvmHeader, ext extBlockApi) map[string]interface{} {
	fields := RPCMarshalHeader(header, ext)
	fields["totalDifficulty"] = (*hexutil.Big)(s.b.GetTd(header.Hash))
	return fields
}

// rpcMarshalBlock uses the generalized output filler, then adds the total difficulty field, which requires
// a `PublicBlockchainAPI`.
func (s *PublicBlockChainAPI) rpcMarshalBlock(b *evmcore.EvmBlock, ext extBlockApi, inclTx bool, fullTx bool) (map[string]interface{}, error) {
	fields, err := RPCMarshalBlock(b, ext, inclTx, fullTx)
	if err != nil {
		return nil, err
	}
	fields["totalDifficulty"] = (*hexutil.Big)(s.b.GetTd(b.Hash))
	return fields, err
}

// RPCTransaction represents a transaction that will serialize to the RPC representation of a transaction
type RPCTransaction struct {
	BlockHash        *common.Hash      `json:"blockHash"`
	BlockNumber      *hexutil.Big      `json:"blockNumber"`
	From             common.Address    `json:"from"`
	Gas              hexutil.Uint64    `json:"gas"`
	GasPrice         *hexutil.Big      `json:"gasPrice"`
	GasFeeCap        *hexutil.Big      `json:"maxFeePerGas,omitempty"`
	GasTipCap        *hexutil.Big      `json:"maxPriorityFeePerGas,omitempty"`
	Hash             common.Hash       `json:"hash"`
	Input            hexutil.Bytes     `json:"input"`
	Nonce            hexutil.Uint64    `json:"nonce"`
	To               *common.Address   `json:"to"`
	TransactionIndex *hexutil.Uint64   `json:"transactionIndex"`
	Value            *hexutil.Big      `json:"value"`
	Type             hexutil.Uint64    `json:"type"`
	Accesses         *types.AccessList `json:"accessList,omitempty"`
	ChainID          *hexutil.Big      `json:"chainId,omitempty"`
	V                *hexutil.Big      `json:"v"`
	R                *hexutil.Big      `json:"r"`
	S                *hexutil.Big      `json:"s"`
}

// newRPCTransaction returns a transaction that will serialize to the RPC
// representation, with the given location metadata set (if available).
func newRPCTransaction(tx *types.Transaction, blockHash common.Hash, blockNumber uint64, index uint64, baseFee *big.Int) *RPCTransaction {
	// Determine the signer. For replay-protected transactions, use the most permissive
	// signer, because we assume that signers are backwards-compatible with old
	// transactions. For non-protected transactions, the homestead signer signer is used
	// because the return value of ChainId is zero for those transactions.
	var signer types.Signer
	if tx.Protected() {
		signer = gsignercache.Wrap(types.LatestSignerForChainID(tx.ChainId()))
	} else {
		signer = gsignercache.Wrap(types.HomesteadSigner{})
	}
	from, _ := internaltx.Sender(signer, tx)
	v, r, s := tx.RawSignatureValues()
	result := &RPCTransaction{
		Type:     hexutil.Uint64(tx.Type()),
		From:     from,
		Gas:      hexutil.Uint64(tx.Gas()),
		GasPrice: (*hexutil.Big)(tx.GasPrice()),
		Hash:     tx.Hash(),
		Input:    hexutil.Bytes(tx.Data()),
		Nonce:    hexutil.Uint64(tx.Nonce()),
		To:       tx.To(),
		Value:    (*hexutil.Big)(tx.Value()),
		V:        (*hexutil.Big)(v),
		R:        (*hexutil.Big)(r),
		S:        (*hexutil.Big)(s),
	}
	if blockHash != (common.Hash{}) {
		result.BlockHash = &blockHash
		result.BlockNumber = (*hexutil.Big)(new(big.Int).SetUint64(blockNumber))
		result.TransactionIndex = (*hexutil.Uint64)(&index)
	}
	switch tx.Type() {
	case types.AccessListTxType:
		al := tx.AccessList()
		result.Accesses = &al
		result.ChainID = (*hexutil.Big)(tx.ChainId())
	case types.DynamicFeeTxType:
		al := tx.AccessList()
		result.Accesses = &al
		result.ChainID = (*hexutil.Big)(tx.ChainId())
		result.GasFeeCap = (*hexutil.Big)(tx.GasFeeCap())
		result.GasTipCap = (*hexutil.Big)(tx.GasTipCap())
		// if the transaction has been mined, compute the effective gas price
		if baseFee != nil && blockHash != (common.Hash{}) {
			// price = min(tip, gasFeeCap - baseFee) + baseFee
			price := math.BigMin(new(big.Int).Add(tx.GasTipCap(), baseFee), tx.GasFeeCap())
			result.GasPrice = (*hexutil.Big)(price)
		} else {
			result.GasPrice = (*hexutil.Big)(tx.GasFeeCap())
		}
	}
	return result
}

// newRPCPendingTransaction returns a pending transaction that will serialize to the RPC representation
func newRPCPendingTransaction(tx *types.Transaction, baseFee *big.Int) *RPCTransaction {
	return newRPCTransaction(tx, common.Hash{}, 0, 0, baseFee)
}

// newRPCTransactionFromBlockIndex returns a transaction that will serialize to the RPC representation.
func newRPCTransactionFromBlockIndex(b *evmcore.EvmBlock, index uint64) *RPCTransaction {
	txs := b.Transactions
	if index >= uint64(len(txs)) {
		return nil
	}
	return newRPCTransaction(txs[index], b.Hash, b.NumberU64(), index, b.BaseFee)
}

// newRPCRawTransactionFromBlockIndex returns the bytes of a transaction given a block and a transaction index.
func newRPCRawTransactionFromBlockIndex(b *evmcore.EvmBlock, index uint64) hexutil.Bytes {
	txs := b.Transactions
	if index >= uint64(len(txs)) {
		return nil
	}
	blob, _ := txs[index].MarshalBinary()
	return blob
}

// newRPCTransactionFromBlockHash returns a transaction that will serialize to the RPC representation.
func newRPCTransactionFromBlockHash(b *evmcore.EvmBlock, hash common.Hash) *RPCTransaction {
	for idx, tx := range b.Transactions {
		if tx.Hash() == hash {
			return newRPCTransactionFromBlockIndex(b, uint64(idx))
		}
	}
	return nil
}

// accessListResult returns an optional accesslist
// Its the result of the `debug_createAccessList` RPC call.
// It contains an error if the transaction itself failed.
type accessListResult struct {
	Accesslist *types.AccessList `json:"accessList"`
	Error      string            `json:"error,omitempty"`
	GasUsed    hexutil.Uint64    `json:"gasUsed"`
}

// CreateAccessList creates a EIP-2930 type AccessList for the given transaction.
// Reexec and BlockNrOrHash can be specified to create the accessList on top of a certain state.
func (s *PublicBlockChainAPI) CreateAccessList(ctx context.Context, args TransactionArgs, blockNrOrHash *rpc.BlockNumberOrHash) (*accessListResult, error) {
	bNrOrHash := rpc.BlockNumberOrHashWithNumber(rpc.PendingBlockNumber)
	if blockNrOrHash != nil {
		bNrOrHash = *blockNrOrHash
	}
	acl, gasUsed, vmerr, err := AccessList(ctx, s.b, bNrOrHash, args)
	if err != nil {
		return nil, err
	}
	result := &accessListResult{Accesslist: &acl, GasUsed: hexutil.Uint64(gasUsed)}
	if vmerr != nil {
		result.Error = vmerr.Error()
	}
	return result, nil
}

// AccessList creates an access list for the given transaction.
// If the accesslist creation fails an error is returned.
// If the transaction itself fails, an vmErr is returned.
func AccessList(ctx context.Context, b Backend, blockNrOrHash rpc.BlockNumberOrHash, args TransactionArgs) (acl types.AccessList, gasUsed uint64, vmErr error, err error) {
	// Retrieve the execution context
	db, header, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
	if db == nil || err != nil {
		return nil, 0, nil, err
	}
	// If the gas amount is not set, extract this as it will depend on access
	// lists and we'll need to reestimate every time
	nogas := args.Gas == nil

	// Ensure any missing fields are filled, extract the recipient and input data
	if err := args.setDefaults(ctx, b); err != nil {
		return nil, 0, nil, err
	}
	var to common.Address
	if args.To != nil {
		to = *args.To
	} else {
		to = crypto.CreateAddress(args.from(), uint64(*args.Nonce))
	}
	// Retrieve the precompiles since they don't need to be added to the access list
	precompiles := vm.ActivePrecompiles(b.ChainConfig().Rules(header.Number))

	// Create an initial tracer
	prevTracer := vm.NewAccessListTracer(nil, args.from(), to, precompiles)
	if args.AccessList != nil {
		prevTracer = vm.NewAccessListTracer(*args.AccessList, args.from(), to, precompiles)
	}
	for {
		// Retrieve the current access list to expand
		accessList := prevTracer.AccessList()
		log.Trace("Creating access list", "input", accessList)

		// If no gas amount was specified, each unique access list needs it's own
		// gas calculation. This is quite expensive, but we need to be accurate
		// and it's convered by the sender only anyway.
		if nogas {
			args.Gas = nil
			if err := args.setDefaults(ctx, b); err != nil {
				return nil, 0, nil, err // shouldn't happen, just in case
			}
		}
		// Copy the original db so we don't modify it
		statedb := db.Copy()
		// Set the accesslist to the last al
		args.AccessList = &accessList
		msg, err := args.ToMessage(b.RPCGasCap(), header.BaseFee)
		if err != nil {
			return nil, 0, nil, err
		}

		// Apply the transaction with the access list tracer
		tracer := vm.NewAccessListTracer(accessList, args.from(), to, precompiles)
		config := u2u.DefaultVMConfig
		config.Tracer = tracer
		config.Debug = true
		config.NoBaseFee = true
		vmenv, _, err := b.GetEVM(ctx, msg, statedb, header, &config)
		if err != nil {
			return nil, 0, nil, err
		}
		res, err := evmcore.ApplyMessage(vmenv, msg, new(evmcore.GasPool).AddGas(msg.Gas()))
		if err != nil {
			return nil, 0, nil, fmt.Errorf("failed to apply transaction: %v err: %v", args.toTransaction().Hash(), err)
		}
		if tracer.Equal(prevTracer) {
			return accessList, res.UsedGas, res.Err, nil
		}
		prevTracer = tracer
	}
}

// PublicTransactionPoolAPI exposes methods for the RPC interface
type PublicTransactionPoolAPI struct {
	b         Backend
	nonceLock *AddrLocker
	signer    types.Signer
}

// NewPublicTransactionPoolAPI creates a new RPC service with methods specific for the transaction pool.
func NewPublicTransactionPoolAPI(b Backend, nonceLock *AddrLocker) *PublicTransactionPoolAPI {
	// The signer used by the API should always be the 'latest' known one because we expect
	// signers to be backwards-compatible with old transactions.
	signer := gsignercache.Wrap(types.LatestSignerForChainID(b.ChainConfig().ChainID))
	return &PublicTransactionPoolAPI{b, nonceLock, signer}
}

// GetBlockTransactionCountByNumber returns the number of transactions in the block with the given block number.
func (s *PublicTransactionPoolAPI) GetBlockTransactionCountByNumber(ctx context.Context, blockNr rpc.BlockNumber) *hexutil.Uint {
	if block, _ := s.b.BlockByNumber(ctx, blockNr); block != nil {
		n := hexutil.Uint(len(block.Transactions))
		return &n
	}
	return nil
}

// GetBlockTransactionCountByHash returns the number of transactions in the block with the given hash.
func (s *PublicTransactionPoolAPI) GetBlockTransactionCountByHash(ctx context.Context, blockHash common.Hash) *hexutil.Uint {
	if block, _ := s.b.BlockByHash(ctx, blockHash); block != nil {
		n := hexutil.Uint(len(block.Transactions))
		return &n
	}
	return nil
}

// GetTransactionByBlockNumberAndIndex returns the transaction for the given block number and index.
func (s *PublicTransactionPoolAPI) GetTransactionByBlockNumberAndIndex(ctx context.Context, blockNr rpc.BlockNumber, index hexutil.Uint) *RPCTransaction {
	if block, _ := s.b.BlockByNumber(ctx, blockNr); block != nil {
		return newRPCTransactionFromBlockIndex(block, uint64(index))
	}
	return nil
}

// GetTransactionByBlockHashAndIndex returns the transaction for the given block hash and index.
func (s *PublicTransactionPoolAPI) GetTransactionByBlockHashAndIndex(ctx context.Context, blockHash common.Hash, index hexutil.Uint) *RPCTransaction {
	if block, _ := s.b.BlockByHash(ctx, blockHash); block != nil {
		return newRPCTransactionFromBlockIndex(block, uint64(index))
	}
	return nil
}

// GetRawTransactionByBlockNumberAndIndex returns the bytes of the transaction for the given block number and index.
func (s *PublicTransactionPoolAPI) GetRawTransactionByBlockNumberAndIndex(ctx context.Context, blockNr rpc.BlockNumber, index hexutil.Uint) hexutil.Bytes {
	if block, _ := s.b.BlockByNumber(ctx, blockNr); block != nil {
		return newRPCRawTransactionFromBlockIndex(block, uint64(index))
	}
	return nil
}

// GetRawTransactionByBlockHashAndIndex returns the bytes of the transaction for the given block hash and index.
func (s *PublicTransactionPoolAPI) GetRawTransactionByBlockHashAndIndex(ctx context.Context, blockHash common.Hash, index hexutil.Uint) hexutil.Bytes {
	if block, _ := s.b.BlockByHash(ctx, blockHash); block != nil {
		return newRPCRawTransactionFromBlockIndex(block, uint64(index))
	}
	return nil
}

// GetTransactionCount returns the number of transactions the given address has sent for the given block number
func (s *PublicTransactionPoolAPI) GetTransactionCount(ctx context.Context, address common.Address, blockNrOrHash rpc.BlockNumberOrHash) (*hexutil.Uint64, error) {
	// Ask transaction pool for the nonce which includes pending transactions
	if blockNr, ok := blockNrOrHash.Number(); ok && blockNr == rpc.PendingBlockNumber {
		nonce, err := s.b.GetPoolNonce(ctx, address)
		if err != nil {
			return nil, err
		}
		return (*hexutil.Uint64)(&nonce), nil
	}
	// Resolve block number and use its state to ask for the nonce
	state, _, err := s.b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
	if state == nil || err != nil {
		return nil, err
	}
	nonce := state.GetNonce(address)
	return (*hexutil.Uint64)(&nonce), state.Error()
}

// GetTransactionByHash returns the transaction for the given hash
func (s *PublicTransactionPoolAPI) GetTransactionByHash(ctx context.Context, hash common.Hash) (*RPCTransaction, error) {
	// Try to return an already finalized transaction
	tx, blockNumber, index, err := s.b.GetTransaction(ctx, hash)
	if err != nil {
		return nil, err
	}
	if tx != nil {
		header, err := s.b.HeaderByNumber(ctx, rpc.BlockNumber(blockNumber))
		if header == nil || err != nil {
			return nil, err
		}
		return newRPCTransaction(tx, header.Hash, blockNumber, index, header.BaseFee), nil
	}
	// No finalized transaction, try to retrieve it from the pool
	if tx := s.b.GetPoolTransaction(hash); tx != nil {
		return newRPCPendingTransaction(tx, s.b.MinGasPrice()), nil
	}

	// Transaction unknown, return as such
	return nil, nil
}

// GetRawTransactionByHash returns the bytes of the transaction for the given hash.
func (s *PublicTransactionPoolAPI) GetRawTransactionByHash(ctx context.Context, hash common.Hash) (hexutil.Bytes, error) {
	// Retrieve a finalized transaction, or a pooled otherwise
	tx, _, _, err := s.b.GetTransaction(ctx, hash)
	if err != nil {
		return nil, err
	}
	if tx == nil {
		if tx = s.b.GetPoolTransaction(hash); tx == nil {
			// Transaction not found anywhere, abort
			return nil, nil
		}
	}
	// Serialize to RLP and return
	return tx.MarshalBinary()
}

// GetTransactionReceipt returns the transaction receipt for the given transaction hash.
func (s *PublicTransactionPoolAPI) GetTransactionReceipt(ctx context.Context, hash common.Hash) (map[string]interface{}, error) {
	tx, blockNumber, index, err := s.b.GetTransaction(ctx, hash)
	if tx == nil || err != nil {
		return nil, err
	}
	header, err := s.b.HeaderByNumber(ctx, rpc.BlockNumber(blockNumber)) // retrieve header to get block hash
	if header == nil || err != nil {
		return nil, err
	}
	receipts, err := s.b.GetReceiptsByNumber(ctx, rpc.BlockNumber(blockNumber))
	if receipts == nil || err != nil {
		return nil, err
	}
	if receipts.Len() <= int(index) {
		return nil, nil
	}
	receipt := receipts[index]

	for _, l := range receipt.Logs {
		l.TxHash = hash
		l.BlockHash = header.Hash
		l.BlockNumber = blockNumber
	}

	// Derive the sender.
	bigblock := new(big.Int).SetUint64(blockNumber)
	signer := gsignercache.Wrap(types.MakeSigner(s.b.ChainConfig(), bigblock))
	from, _ := internaltx.Sender(signer, tx)

	fields := map[string]interface{}{
		"blockHash":         header.Hash,
		"blockNumber":       hexutil.Uint64(blockNumber),
		"transactionHash":   hash,
		"transactionIndex":  hexutil.Uint64(index),
		"from":              from,
		"to":                tx.To(),
		"gasUsed":           hexutil.Uint64(receipt.GasUsed),
		"cumulativeGasUsed": hexutil.Uint64(receipt.CumulativeGasUsed),
		"contractAddress":   nil,
		"logs":              receipt.Logs,
		"logsBloom":         &receipt.Bloom,
		"type":              hexutil.Uint(tx.Type()),
	}
	// Assign the effective gas price paid
	if header.BaseFee == nil {
		fields["effectiveGasPrice"] = hexutil.Uint64(tx.GasPrice().Uint64())
	} else {
		gasPrice := new(big.Int).Add(header.BaseFee, tx.EffectiveGasTipValue(header.BaseFee))
		fields["effectiveGasPrice"] = hexutil.Uint64(gasPrice.Uint64())
	}
	// Assign receipt status or post state.
	if len(receipt.PostState) > 0 {
		fields["root"] = hexutil.Bytes(receipt.PostState)
	} else {
		fields["status"] = hexutil.Uint(receipt.Status)
	}
	if receipt.Logs == nil {
		fields["logs"] = [][]*types.Log{}
	}
	// If the ContractAddress is 20 0x0 bytes, assume it is not a contract creation
	if tx.To() == nil {
		fields["contractAddress"] = receipt.ContractAddress
	}
	return fields, nil
}

// sign is a helper function that signs a transaction with the private key of the given address.
func (s *PublicTransactionPoolAPI) sign(addr common.Address, tx *types.Transaction) (*types.Transaction, error) {
	// Look up the wallet containing the requested signer
	account := accounts.Account{Address: addr}

	wallet, err := s.b.AccountManager().Find(account)
	if err != nil {
		return nil, err
	}
	// Request the wallet to sign the transaction
	return wallet.SignTx(account, tx, s.b.ChainConfig().ChainID)
}

// SubmitTransaction is a helper function that submits tx to txPool and logs a message.
func SubmitTransaction(ctx context.Context, b Backend, tx *types.Transaction) (common.Hash, error) {
	// If the transaction fee cap is already specified, ensure the
	// fee of the given transaction is _reasonable_.
	if err := checkTxFee(tx.GasPrice(), tx.Gas(), b.RPCTxFeeCap()); err != nil {
		return common.Hash{}, err
	}
	if !b.UnprotectedAllowed() && !tx.Protected() {
		// Ensure only eip155 signed transactions are submitted if EIP155Required is set.
		return common.Hash{}, errors.New("only replay-protected (EIP-155) transactions allowed over RPC")
	}
	if err := b.SendTx(ctx, tx); err != nil {
		return common.Hash{}, err
	} // Print a log with full tx details for manual investigations and interventions
	signer := gsignercache.Wrap(types.MakeSigner(b.ChainConfig(), b.CurrentBlock().Number))
	from, err := types.Sender(signer, tx)
	if err != nil {
		return common.Hash{}, err
	}

	if tx.To() == nil {
		addr := crypto.CreateAddress(from, tx.Nonce())
		log.Info("Submitted contract creation", "hash", tx.Hash().Hex(), "from", from, "nonce", tx.Nonce(), "contract", addr.Hex(), "value", tx.Value())
	} else {
		log.Info("Submitted transaction", "hash", tx.Hash().Hex(), "from", from, "nonce", tx.Nonce(), "recipient", tx.To(), "value", tx.Value())
	}
	return tx.Hash(), nil
}

// SendTransaction creates a transaction for the given argument, sign it and submit it to the
// transaction pool.
func (s *PublicTransactionPoolAPI) SendTransaction(ctx context.Context, args TransactionArgs) (common.Hash, error) {
	// Look up the wallet containing the requested signer
	account := accounts.Account{Address: args.from()}

	wallet, err := s.b.AccountManager().Find(account)
	if err != nil {
		return common.Hash{}, err
	}

	if args.Nonce == nil {
		// Hold the addresse's mutex around signing to prevent concurrent assignment of
		// the same nonce to multiple accounts.
		s.nonceLock.LockAddr(args.from())
		defer s.nonceLock.UnlockAddr(args.from())
	}

	// Set some sanity defaults and terminate on failure
	if err := args.setDefaults(ctx, s.b); err != nil {
		return common.Hash{}, err
	}
	// Assemble the transaction and sign with the wallet
	tx := args.toTransaction()

	signed, err := wallet.SignTx(account, tx, s.b.ChainConfig().ChainID)
	if err != nil {
		return common.Hash{}, err
	}
	return SubmitTransaction(ctx, s.b, signed)
}

// FillTransaction fills the defaults (nonce, gas, gasPrice or 1559 fields)
// on a given unsigned transaction, and returns it to the caller for further
// processing (signing + broadcast).
func (s *PublicTransactionPoolAPI) FillTransaction(ctx context.Context, args TransactionArgs) (*SignTransactionResult, error) {
	// Set some sanity defaults and terminate on failure
	if err := args.setDefaults(ctx, s.b); err != nil {
		return nil, err
	}
	// Assemble the transaction and obtain rlp
	tx := args.toTransaction()
	data, err := tx.MarshalBinary()
	if err != nil {
		return nil, err
	}
	return &SignTransactionResult{data, tx}, nil
}

// SendRawTransaction will add the signed transaction to the transaction pool.
// The sender is responsible for signing the transaction and using the correct nonce.
func (s *PublicTransactionPoolAPI) SendRawTransaction(ctx context.Context, encodedTx hexutil.Bytes) (common.Hash, error) {
	tx := new(types.Transaction)
	if err := tx.UnmarshalBinary(encodedTx); err != nil {
		return common.Hash{}, err
	}
	return SubmitTransaction(ctx, s.b, tx)
}

// Sign calculates an ECDSA signature for:
// keccack256("\x19Ethereum Signed Message:\n" + len(message) + message).
//
// Note, the produced signature conforms to the secp256k1 curve R, S and V values,
// where the V value will be 27 or 28 for legacy reasons.
//
// The account associated with addr must be unlocked.
//
// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign
func (s *PublicTransactionPoolAPI) Sign(addr common.Address, data hexutil.Bytes) (hexutil.Bytes, error) {
	// Look up the wallet containing the requested signer
	account := accounts.Account{Address: addr}

	wallet, err := s.b.AccountManager().Find(account)
	if err != nil {
		return nil, err
	}
	// Sign the requested hash with the wallet
	signature, err := wallet.SignText(account, data)
	if err == nil {
		signature[64] += 27 // Transform V from 0/1 to 27/28 according to the yellow paper
	}
	return signature, err
}

// SignTransactionResult represents a RLP encoded signed transaction.
type SignTransactionResult struct {
	Raw hexutil.Bytes      `json:"raw"`
	Tx  *types.Transaction `json:"tx"`
}

// SignTransaction will sign the given transaction with the from account.
// The node needs to have the private key of the account corresponding with
// the given from address and it needs to be unlocked.
func (s *PublicTransactionPoolAPI) SignTransaction(ctx context.Context, args TransactionArgs) (*SignTransactionResult, error) {
	if args.Gas == nil {
		return nil, fmt.Errorf("gas not specified")
	}
	if args.GasPrice == nil && (args.MaxPriorityFeePerGas == nil || args.MaxFeePerGas == nil) {
		return nil, fmt.Errorf("missing gasPrice or maxFeePerGas/maxPriorityFeePerGas")
	}
	if args.Nonce == nil {
		return nil, fmt.Errorf("nonce not specified")
	}
	if err := args.setDefaults(ctx, s.b); err != nil {
		return nil, err
	}
	// Before actually sign the transaction, ensure the transaction fee is reasonable.
	tx := args.toTransaction()
	if err := checkTxFee(tx.GasPrice(), tx.Gas(), s.b.RPCTxFeeCap()); err != nil {
		return nil, err
	}
	signed, err := s.sign(args.from(), tx)
	if err != nil {
		return nil, err
	}
	data, err := signed.MarshalBinary()
	if err != nil {
		return nil, err
	}
	return &SignTransactionResult{data, signed}, nil
}

// PendingTransactions returns the transactions that are in the transaction pool
// and have a from address that is one of the accounts this node manages.
func (s *PublicTransactionPoolAPI) PendingTransactions() ([]*RPCTransaction, error) {
	pending, err := s.b.GetPoolTransactions()
	if err != nil {
		return nil, err
	}
	accounts := make(map[common.Address]struct{})
	for _, wallet := range s.b.AccountManager().Wallets() {
		for _, account := range wallet.Accounts() {
			accounts[account.Address] = struct{}{}
		}
	}
	transactions := make([]*RPCTransaction, 0, len(pending))
	for _, tx := range pending {
		from, _ := internaltx.Sender(s.signer, tx)
		if _, exists := accounts[from]; exists {
			transactions = append(transactions, newRPCPendingTransaction(tx, s.b.MinGasPrice()))
		}
	}
	return transactions, nil
}

// Resend accepts an existing transaction and a new gas price and limit. It will remove
// the given transaction from the pool and reinsert it with the new gas price and limit.
func (s *PublicTransactionPoolAPI) Resend(ctx context.Context, sendArgs TransactionArgs, gasPrice *hexutil.Big, gasLimit *hexutil.Uint64) (common.Hash, error) {
	if sendArgs.Nonce == nil {
		return common.Hash{}, fmt.Errorf("missing transaction nonce in transaction spec")
	}
	if err := sendArgs.setDefaults(ctx, s.b); err != nil {
		return common.Hash{}, err
	}
	matchTx := sendArgs.toTransaction()

	// Before replacing the old transaction, ensure the _new_ transaction fee is reasonable.
	var price = matchTx.GasPrice()
	if gasPrice != nil {
		price = gasPrice.ToInt()
	}
	var gas = matchTx.Gas()
	if gasLimit != nil {
		gas = uint64(*gasLimit)
	}
	if err := checkTxFee(price, gas, s.b.RPCTxFeeCap()); err != nil {
		return common.Hash{}, err
	}
	// Iterate the pending list for replacement
	pending, err := s.b.GetPoolTransactions()
	if err != nil {
		return common.Hash{}, err
	}

	for _, p := range pending {
		wantSigHash := s.signer.Hash(matchTx)
		pFrom, err := types.Sender(s.signer, p)
		if err == nil && pFrom == sendArgs.from() && s.signer.Hash(p) == wantSigHash {
			// Match. Re-sign and send the transaction.
			if gasPrice != nil && (*big.Int)(gasPrice).Sign() != 0 {
				sendArgs.GasPrice = gasPrice
			}
			if gasLimit != nil && *gasLimit != 0 {
				sendArgs.Gas = gasLimit
			}
			signedTx, err := s.sign(sendArgs.from(), sendArgs.toTransaction())
			if err != nil {
				return common.Hash{}, err
			}
			if err = s.b.SendTx(ctx, signedTx); err != nil {
				return common.Hash{}, err
			}
			return signedTx.Hash(), nil
		}
	}
	return common.Hash{}, fmt.Errorf("transaction %#x not found", matchTx.Hash())
}

// PublicDebugAPI is the collection of Ethereum APIs exposed over the public
// debugging endpoint.
type PublicDebugAPI struct {
	b Backend
}

// NewPublicDebugAPI creates a new API definition for the public debug methods
// of the Ethereum service.
func NewPublicDebugAPI(b Backend) *PublicDebugAPI {
	return &PublicDebugAPI{b: b}
}

// GetBlockRlp retrieves the RLP encoded for of a single block.
func (api *PublicDebugAPI) GetBlockRlp(ctx context.Context, number uint64) (string, error) {
	block, _ := api.b.BlockByNumber(ctx, rpc.BlockNumber(number))
	if block == nil {
		return "", fmt.Errorf("block #%d not found", number)
	}
	encoded, err := rlp.EncodeToBytes(block)
	if err != nil {
		return "", err
	}
	return fmt.Sprintf("%x", encoded), nil
}

// TestSignCliqueBlock fetches the given block number, and attempts to sign it as a clique header with the
// given address, returning the address of the recovered signature
//
// This is a temporary method to debug the externalsigner integration,
func (api *PublicDebugAPI) TestSignCliqueBlock(ctx context.Context, address common.Address, number uint64) (common.Address, error) {
	return common.Address{}, errors.New("Clique isn't supported")
}

// PrintBlock retrieves a block and returns its pretty printed form.
func (api *PublicDebugAPI) PrintBlock(ctx context.Context, number uint64) (string, error) {
	block, err := api.b.BlockByNumber(ctx, rpc.BlockNumber(number))
	if err != nil {
		return "", err
	}
	if block == nil {
		return "", fmt.Errorf("block #%d not found", number)
	}
	return spew.Sdump(block), nil
}

// BlocksTransactionTimes returns the map time => number of transactions
// This data may be used to draw a histogram to calculate a peak TPS of a range of blocks
func (api *PublicDebugAPI) BlocksTransactionTimes(ctx context.Context, untilBlock rpc.BlockNumber, maxBlocks hexutil.Uint64) (map[hexutil.Uint64]hexutil.Uint, error) {

	until, err := api.b.HeaderByNumber(ctx, untilBlock)
	if until == nil || err != nil {
		return nil, err
	}
	untilN := until.Number.Uint64()
	times := map[hexutil.Uint64]hexutil.Uint{}
	for i := untilN; i >= 1 && i+uint64(maxBlocks) > untilN; i-- {
		b, err := api.b.BlockByNumber(ctx, rpc.BlockNumber(i))
		if b == nil || err != nil {
			return nil, err
		}
		if b.Transactions.Len() == 0 {
			continue
		}
		times[hexutil.Uint64(b.Time)] += hexutil.Uint(b.Transactions.Len())
	}

	return times, nil
}

// TraceConfig holds extra parameters to trace functions.
type TraceConfig struct {
	*vm.LogConfig
	Tracer  *string
	Timeout *string
	Reexec  *uint64
}

// TraceCallConfig is the config for traceCall API. It holds one more
// field to override the state for tracing.
type TraceCallConfig struct {
	TraceConfig
	StateOverrides *StateOverride
	BlockOverrides *BlockOverrides
}

// TraceTransaction returns the structured logs created during the execution of EVM
// and returns them as a JSON object.
func (api *PublicDebugAPI) TraceTransaction(ctx context.Context, hash common.Hash, config *TraceConfig) (interface{}, error) {
	tx, blockNumber, index, err := api.b.GetTransaction(ctx, hash)
	if err != nil {
		return nil, err
	}
	if tx == nil {
		return nil, fmt.Errorf("transaction %s not found", hash.Hex())
	}

	// It shouldn't happen in practice.
	if blockNumber == 0 {
		return nil, errors.New("genesis is not traceable")
	}

	block, err := api.b.BlockByNumber(ctx, rpc.BlockNumber(blockNumber))
	if err != nil {
		return nil, errors.New("cannot get block from db")
	}

	msg, vmctx, statedb, err := api.stateAtTransaction(ctx, block, int(index))
	if err != nil {
		return nil, err
	}

	txctx := &tracers.Context{
		BlockHash: block.Hash,
		TxIndex:   int(index),
		TxHash:    hash,
	}

	return api.traceTx(ctx, msg, txctx, vmctx, statedb, config)
}

// TraceCall lets you trace a given eth_call. It collects the structured logs
// created during the execution of EVM if the given transaction was added on
// top of the provided block and returns them as a JSON object.
// You can provide -2 as a block number to trace on top of the pending block.
func (api *PublicDebugAPI) TraceCall(ctx context.Context, args TransactionArgs, blockNrOrHash rpc.BlockNumberOrHash, config *TraceCallConfig) (interface{}, error) {
	// Try to retrieve the specified block
	var (
		err   error
		block *evmcore.EvmBlock
	)
	if hash, ok := blockNrOrHash.Hash(); ok {
		block, err = api.blockByHash(ctx, hash)
	} else if number, ok := blockNrOrHash.Number(); ok {
		block, err = api.blockByNumber(ctx, number)
	} else {
		return nil, errors.New("invalid arguments; neither block nor hash specified")
	}
	if err != nil {
		return nil, err
	}
	// try to recompute the state
	reexec := defaultTraceReexec
	if config != nil && config.Reexec != nil {
		reexec = *config.Reexec
	}
	statedb, err := api.b.StateAtBlock(ctx, block, reexec, nil, true)
	if err != nil {
		return nil, err
	}
	// Apply the customized state rules if required.
	if config != nil {
		if err := config.StateOverrides.Apply(statedb); err != nil {
			return nil, err
		}
	}
	// Execute the trace
	msg, err := args.ToMessage(api.b.RPCGasCap(), block.EthHeader().BaseFee)
	if err != nil {
		return nil, err
	}
	vmctx := evmcore.NewEVMBlockContext(block.Header(), api.chainContext(ctx), nil)

	var traceConfig *TraceConfig
	if config != nil {
		traceConfig = &TraceConfig{
			LogConfig: config.LogConfig,
			Tracer:    config.Tracer,
			Timeout:   config.Timeout,
			Reexec:    config.Reexec,
		}
	}
	return api.traceTx(ctx, msg, new(tracers.Context), vmctx, statedb, traceConfig)
}

// traceTx configures a new tracer according to the provided configuration, and
// executes the given message in the provided environment. The return value will
// be tracer dependent.
func (api *PublicDebugAPI) traceTx(ctx context.Context, message evmcore.Message, txctx *tracers.Context, vmctx vm.BlockContext, statedb *state.StateDB, config *TraceConfig) (interface{}, error) {
	// Assemble the structured logger or the JavaScript tracer
	var (
		tracer    vm.Tracer
		err       error
		txContext = evmcore.NewEVMTxContext(message)
	)

	switch {
	case config == nil:
		tracer = vm.NewStructLogger(nil)
	case config.Tracer != nil:
		// Define a meaningful timeout of a single transaction trace
		timeout := defaultTraceTimeout
		if config.Timeout != nil {
			if timeout, err = time.ParseDuration(*config.Timeout); err != nil {
				return nil, err
			}
		}
		if t, err := tracers.New(*config.Tracer, txctx); err != nil {
			return nil, err
		} else {
			deadlineCtx, cancel := context.WithTimeout(ctx, timeout)
			go func() {
				<-deadlineCtx.Done()
				if errors.Is(deadlineCtx.Err(), context.DeadlineExceeded) {
					t.Stop(errors.New("execution timeout"))
				}
			}()
			defer cancel()
			tracer = t
		}
	default:
		tracer = vm.NewStructLogger(config.LogConfig)
	}

	// Run the transaction with tracing enabled.
	evmconfig := u2u.DefaultVMConfig
	evmconfig.Tracer = tracer
	evmconfig.Debug = true
	evmconfig.NoBaseFee = true
	vmenv := vm.NewEVM(vmctx, txContext, statedb, api.b.ChainConfig(), evmconfig)

	// Call Prepare to clear out the statedb access list
	statedb.Prepare(txctx.TxHash, txctx.TxIndex)

	result, err := evmcore.ApplyMessage(vmenv, message, new(evmcore.GasPool).AddGas(message.Gas()))
	if err != nil {
		return nil, fmt.Errorf("tracing failed: %w", err)
	}

	// Depending on the tracer type, format and return the output.
	switch tracer := tracer.(type) {
	case *vm.StructLogger:
		// If the result contains a revert reason, return it.
		returnVal := fmt.Sprintf("%x", result.Return())
		if len(result.Revert()) > 0 {
			returnVal = fmt.Sprintf("%x", result.Revert())
		}
		return &ExecutionResult{
			Gas:         result.UsedGas,
			Failed:      result.Failed(),
			ReturnValue: returnVal,
			StructLogs:  FormatLogs(tracer.StructLogs()),
		}, nil

	case *tracers.Tracer:
		result, err := tracer.GetResult()
		if err != nil && result == nil {
			// Only for tracer called callTracer
			if config.Tracer != nil && strings.Compare(*config.Tracer, "callTracer") == 0 {
				if strings.Contains(err.Error(), "cannot read property 'toString' of undefined") {
					log.Debug("error when debug with callTracer", "err", err.Error())
					callTracer, _ := tracers.New(*config.Tracer, txctx)
					callTracer.CaptureStart(vmenv, message.From(), *message.To(), false, message.Data(), message.Gas(), message.Value())
					callTracer.CaptureEnd([]byte{}, message.Gas(), time.Duration(0), fmt.Errorf("execution reverted"))
					result, err = callTracer.GetResult()
				}
			}
		}
		return result, err

	default:
		panic(fmt.Sprintf("bad tracer type %T", tracer))
	}
}

// txTraceResult is the result of a single transaction trace.
type txTraceResult struct {
	Result interface{} `json:"result,omitempty"` // Trace results produced by the tracer
	Error  string      `json:"error,omitempty"`  // Trace failure produced by the tracer
}

// txTraceTask represents a single transaction trace task when an entire block
// is being traced.
type txTraceTask struct {
	statedb *state.StateDB // Intermediate state prepped for tracing
	index   int            // Transaction offset in the block
}

// TraceBlockByNumber returns the structured logs created during the execution of
// EVM and returns them as a JSON object.
func (api *PublicDebugAPI) TraceBlockByNumber(ctx context.Context, number rpc.BlockNumber, config *TraceConfig) ([]*txTraceResult, error) {
	block, err := api.blockByNumber(ctx, number)
	if err != nil {
		return nil, err
	}
	return api.traceBlock(ctx, block, config)
}

// TraceBlockByHash returns the structured logs created during the execution of
// EVM and returns them as a JSON object.
func (api *PublicDebugAPI) TraceBlockByHash(ctx context.Context, hash common.Hash, config *TraceConfig) ([]*txTraceResult, error) {
	block, err := api.blockByHash(ctx, hash)
	if err != nil {
		return nil, err
	}
	return api.traceBlock(ctx, block, config)
}

// chainContext constructs the context reader which is used by the evm for reading
// the necessary chain context.
func (api *PublicDebugAPI) chainContext(ctx context.Context) evmcore.DummyChain {
	return NewChainContext(ctx, api.b)
}

// blockByNumber is the wrapper of the chain access function offered by the backend.
// It will return an error if the block is not found.
func (api *PublicDebugAPI) blockByNumber(ctx context.Context, number rpc.BlockNumber) (*evmcore.EvmBlock, error) {
	block, err := api.b.BlockByNumber(ctx, number)
	if err != nil {
		return nil, err
	}
	if block == nil {
		return nil, fmt.Errorf("block #%d not found", number)
	}
	return block, nil
}

// blockByHash is the wrapper of the chain access function offered by the backend.
// It will return an error if the block is not found.
func (api *PublicDebugAPI) blockByHash(ctx context.Context, hash common.Hash) (*evmcore.EvmBlock, error) {
	block, err := api.b.BlockByHash(ctx, hash)
	if err != nil {
		return nil, err
	}
	if block == nil {
		return nil, fmt.Errorf("block %s not found", hash.Hex())
	}
	return block, nil
}

// traceBlock configures a new tracer according to the provided configuration, and
// executes all the transactions contained within. The return value will be one item
// per transaction, dependent on the requestd tracer.
func (api *PublicDebugAPI) traceBlock(ctx context.Context, block *evmcore.EvmBlock, config *TraceConfig) ([]*txTraceResult, error) {
	if block.NumberU64() == 0 {
		return nil, errors.New("genesis is not traceable")
	}
	statedb, _, err := api.b.StateAndHeaderByNumberOrHash(ctx, rpc.BlockNumberOrHashWithHash(block.ParentHash, false))
	if err != nil {
		return nil, err
	}
	// Execute all the transaction contained within the block concurrently
	var (
		signer  = types.MakeSigner(api.b.ChainConfig(), block.Number)
		txs     = block.Transactions
		results = make([]*txTraceResult, len(txs))

		pend = new(sync.WaitGroup)
		jobs = make(chan *txTraceTask, len(txs))
	)
	threads := runtime.NumCPU()
	if threads > len(txs) {
		threads = len(txs)
	}

	blockHeader := block.Header()
	blockHash := block.Hash
	for th := 0; th < threads; th++ {
		pend.Add(1)
		go func() {
			defer pend.Done()
			blockCtx := api.b.GetBlockContext(blockHeader)

			// Fetch and execute the next transaction trace tasks
			for task := range jobs {
				msg, _ := txs[task.index].AsMessage(signer, block.BaseFee)
				txctx := &tracers.Context{
					BlockHash: blockHash,
					TxIndex:   task.index,
					TxHash:    txs[task.index].Hash(),
				}
				res, err := api.traceTx(ctx, msg, txctx, blockCtx, task.statedb, config)
				if err != nil {
					results[task.index] = &txTraceResult{Error: err.Error()}
					continue
				}
				results[task.index] = &txTraceResult{Result: res}
			}
		}()
	}
	// Feed the transactions into the tracers and return
	blockCtx := api.b.GetBlockContext(blockHeader)
	var failed error
	for i, tx := range txs {
		// Send the trace task over for execution
		jobs <- &txTraceTask{statedb: statedb.Copy(), index: i}

		// Generate the next state snapshot fast without tracing
		msg, _ := tx.AsMessage(signer, block.BaseFee)
		statedb.Prepare(tx.Hash(), i)
		vmenv := vm.NewEVM(blockCtx, evmcore.NewEVMTxContext(msg), statedb, api.b.ChainConfig(), u2u.DefaultVMConfig)
		if _, err := evmcore.ApplyMessage(vmenv, msg, new(evmcore.GasPool).AddGas(msg.Gas())); err != nil {
			failed = err
			break
		}
		// Finalize the state so any modifications are written to the trie
		statedb.Finalise(vmenv.ChainConfig().IsByzantium(block.Number) || vmenv.ChainConfig().IsEIP158(block.Number))
	}
	close(jobs)
	pend.Wait()

	// If execution failed in between, abort
	if failed != nil {
		return nil, failed
	}
	return results, nil
}

// stateAtTransaction returns the execution environment of a certain transaction.
func (api *PublicDebugAPI) stateAtTransaction(ctx context.Context, block *evmcore.EvmBlock, txIndex int) (evmcore.Message, vm.BlockContext, *state.StateDB, error) {
	// Short circuit if it's genesis block.
	if block.NumberU64() == 0 {
		return nil, vm.BlockContext{}, nil, errors.New("no transaction in genesis")
	}
	// Lookup the statedb of parent block from the live database,
	// otherwise regenerate it on the flight.
	statedb, _, err := api.b.StateAndHeaderByNumberOrHash(ctx, rpc.BlockNumberOrHashWithHash(block.ParentHash, false))
	if err != nil {
		return nil, vm.BlockContext{}, nil, err
	}
	if txIndex == 0 && len(block.Transactions) == 0 {
		return nil, vm.BlockContext{}, statedb, nil
	}
	// Recompute transactions up to the target index.
	signer := gsignercache.Wrap(types.MakeSigner(api.b.ChainConfig(), block.Number))
	for idx, tx := range block.Transactions {
		// Assemble the transaction call message and return if the requested offset
		msg, _ := tx.AsMessage(signer, block.BaseFee)
		txContext := evmcore.NewEVMTxContext(msg)
		context := api.b.GetBlockContext(block.Header())
		if idx == txIndex {
			return msg, context, statedb, nil
		}
		// Not yet the searched for transaction, execute on top of the current state
		vmenv := vm.NewEVM(context, txContext, statedb, api.b.ChainConfig(), u2u.DefaultVMConfig)
		statedb.Prepare(tx.Hash(), idx)
		if _, err := evmcore.ApplyMessage(vmenv, msg, new(evmcore.GasPool).AddGas(tx.Gas())); err != nil {
			return nil, vm.BlockContext{}, nil, fmt.Errorf("transaction %#x failed: %v", tx.Hash(), err)
		}
		// Ensure any modifications are committed to the state
		statedb.Finalise(vmenv.ChainConfig().IsByzantium(block.Number) || vmenv.ChainConfig().IsEIP158(block.Number))
	}
	return nil, vm.BlockContext{}, nil, fmt.Errorf("transaction index %d out of range for block %#x", txIndex, block.Hash)
}

// PrivateDebugAPI is the collection of Ethereum APIs exposed over the private
// debugging endpoint.
type PrivateDebugAPI struct {
	b Backend
}

// NewPrivateDebugAPI creates a new API definition for the private debug methods
// of the Ethereum service.
func NewPrivateDebugAPI(b Backend) *PrivateDebugAPI {
	return &PrivateDebugAPI{b: b}
}

// ChaindbProperty returns leveldb properties of the key-value database.
func (api *PrivateDebugAPI) ChaindbProperty(property string) (string, error) {
	if property == "" {
		property = "stats"
	}
	return api.b.ChainDb().Stat(property)
}

// ChaindbCompact flattens the entire key-value database into a single level,
// removing all unused slots and merging all keys.
func (api *PrivateDebugAPI) ChaindbCompact() error {
	if err := compactdb.Compact(ethdb2udb.Wrap(api.b.ChainDb()), "EVM", 64*opt.GiB); err != nil {
		log.Error("Database compaction failed", "err", err)
		return err
	}
	return nil
}

// SetHead rewinds the head of the blockchain to a previous block.
func (api *PrivateDebugAPI) SetHead(number hexutil.Uint64) error {
	return errors.New("hashgraph cannot rewind blocks due to the BFT algorithm")
}

// PublicNetAPI offers network related RPC methods
type PublicNetAPI struct {
	net            *p2p.Server
	networkVersion uint64
}

// NewPublicNetAPI creates a new net API instance.
func NewPublicNetAPI(net *p2p.Server, networkVersion uint64) *PublicNetAPI {
	return &PublicNetAPI{net, networkVersion}
}

// Listening returns an indication if the node is listening for network connections.
func (s *PublicNetAPI) Listening() bool {
	return true // always listening
}

// PeerCount returns the number of connected peers
func (s *PublicNetAPI) PeerCount() hexutil.Uint {
	return hexutil.Uint(s.net.PeerCount())
}

// Version returns the current ethereum protocol version.
func (s *PublicNetAPI) Version() string {
	return fmt.Sprintf("%d", s.networkVersion)
}

// checkTxFee is an internal function used to check whether the fee of
// the given transaction is _reasonable_(under the cap).
func checkTxFee(gasPrice *big.Int, gas uint64, cap float64) error {
	// Short circuit if there is no cap for transaction fee at all.
	if cap == 0 {
		return nil
	}
	feeEth := new(big.Float).Quo(new(big.Float).SetInt(new(big.Int).Mul(gasPrice, new(big.Int).SetUint64(gas))), new(big.Float).SetInt(big.NewInt(params.Ether)))
	feeFloat, _ := feeEth.Float64()
	if feeFloat > cap {
		return fmt.Errorf("tx fee (%.2f U2U) exceeds the configured cap (%.2f U2U)", feeFloat, cap)
	}
	return nil
}

// toHexSlice creates a slice of hex-strings based on []byte.
func toHexSlice(b [][]byte) []string {
	r := make([]string, len(b))
	for i := range b {
		r[i] = hexutil.Encode(b[i])
	}
	return r
}