// Copyright 2016 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 ethclient provides a client for the Ethereum RPC API.
package ethclient

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"math/big"
	"time"

	"github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/rpc"
)

// Client defines typed wrappers for the Ethereum RPC API.
type Client struct {
	c *rpc.Client
}

// Dial connects a client to the given URL.
func Dial(rawurl string) (*Client, error) {
	return DialContext(context.Background(), rawurl)
}

// DialContext connects a client to the given URL with context.
func DialContext(ctx context.Context, rawurl string) (*Client, error) {
	c, err := rpc.DialContext(ctx, rawurl)
	if err != nil {
		return nil, err
	}
	return NewClient(c), nil
}

// NewClient creates a client that uses the given RPC client.
func NewClient(c *rpc.Client) *Client {
	return &Client{c}
}

// Close closes the underlying RPC connection.
func (ec *Client) Close() {
	ec.c.Close()
}

// Client gets the underlying RPC client.
func (ec *Client) Client() *rpc.Client {
	return ec.c
}

// Blockchain Access

// ChainID retrieves the current chain ID for transaction replay protection.
func (ec *Client) ChainID(ctx context.Context) (*big.Int, error) {
	var result hexutil.Big
	err := ec.c.CallContext(ctx, &result, "eth_chainId")
	if err != nil {
		return nil, err
	}
	return (*big.Int)(&result), err
}

// BlockByHash returns the given full block.
//
// Note that loading full blocks requires two requests. Use HeaderByHash
// if you don't need all transactions or uncle headers.
func (ec *Client) BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error) {
	return ec.getBlock(ctx, "eth_getBlockByHash", hash, true)
}

// BlockByNumber returns a block from the current canonical chain.
// If `number` is nil, the latest known block is returned.
//
// Use `HeaderByNumber` if you don't need full transaction data or uncle headers.
//
// Supported special block number tags:
// - `earliest`  : The genesis (earliest) block
// - `latest`    : The most recently included block
// - `safe`      : The latest safe head block
// - `finalized` : The latest finalized block
// - `pending`   : The pending block
//
// Example usage:
//
// ```go
// BlockByNumber(context.Background(), big.NewInt(int64(rpc.LatestBlockNumber)))
// ```
func (ec *Client) BlockByNumber(ctx context.Context, number *big.Int) (*types.Block, error) {
	return ec.getBlock(ctx, "eth_getBlockByNumber", toBlockNumArg(number), true)
}

// BlockNumber returns the most recent block number
func (ec *Client) BlockNumber(ctx context.Context) (uint64, error) {
	var result hexutil.Uint64
	err := ec.c.CallContext(ctx, &result, "eth_blockNumber")
	return uint64(result), err
}

// PeerCount returns the number of p2p peers as reported by the net_peerCount method.
func (ec *Client) PeerCount(ctx context.Context) (uint64, error) {
	var result hexutil.Uint64
	err := ec.c.CallContext(ctx, &result, "net_peerCount")
	return uint64(result), err
}

// BlockReceipts returns the receipts of a given block number or hash.
func (ec *Client) BlockReceipts(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) ([]*types.Receipt, error) {
	var r []*types.Receipt
	err := ec.c.CallContext(ctx, &r, "eth_getBlockReceipts", blockNrOrHash)
	if err == nil && r == nil {
		return nil, ethereum.NotFound
	}
	return r, err
}

type rpcBlock struct {
	Hash         *common.Hash        `json:"hash"`
	Transactions []rpcTransaction    `json:"transactions"`
	UncleHashes  []common.Hash       `json:"uncles"`
	Withdrawals  []*types.Withdrawal `json:"withdrawals,omitempty"`
}

func (ec *Client) getBlock(ctx context.Context, method string, args ...interface{}) (*types.Block, error) {
	var raw json.RawMessage
	err := ec.c.CallContext(ctx, &raw, method, args...)
	if err != nil {
		return nil, err
	}

	// Decode header and transactions.
	var head *types.Header
	if err := json.Unmarshal(raw, &head); err != nil {
		return nil, err
	}
	// When the block is not found, the API returns JSON null.
	if head == nil {
		return nil, ethereum.NotFound
	}

	var body rpcBlock
	if err := json.Unmarshal(raw, &body); err != nil {
		return nil, err
	}
	// Pending blocks don't return a block hash, compute it for sender caching.
	if body.Hash == nil {
		tmp := head.Hash()
		body.Hash = &tmp
	}

	// Quick-verify transaction and uncle lists. This mostly helps with debugging the server.
	if head.UncleHash == types.EmptyUncleHash && len(body.UncleHashes) > 0 {
		return nil, errors.New("server returned non-empty uncle list but block header indicates no uncles")
	}
	if head.UncleHash != types.EmptyUncleHash && len(body.UncleHashes) == 0 {
		return nil, errors.New("server returned empty uncle list but block header indicates uncles")
	}
	if head.TxHash == types.EmptyTxsHash && len(body.Transactions) > 0 {
		return nil, errors.New("server returned non-empty transaction list but block header indicates no transactions")
	}
	if head.TxHash != types.EmptyTxsHash && len(body.Transactions) == 0 {
		return nil, errors.New("server returned empty transaction list but block header indicates transactions")
	}
	// Load uncles because they are not included in the block response.
	var uncles []*types.Header
	if len(body.UncleHashes) > 0 {
		uncles = make([]*types.Header, len(body.UncleHashes))
		reqs := make([]rpc.BatchElem, len(body.UncleHashes))
		for i := range reqs {
			reqs[i] = rpc.BatchElem{
				Method: "eth_getUncleByBlockHashAndIndex",
				Args:   []interface{}{body.Hash, hexutil.EncodeUint64(uint64(i))},
				Result: &uncles[i],
			}
		}
		if err := ec.c.BatchCallContext(ctx, reqs); err != nil {
			return nil, err
		}
		for i := range reqs {
			if reqs[i].Error != nil {
				return nil, reqs[i].Error
			}
			if uncles[i] == nil {
				return nil, fmt.Errorf("got null header for uncle %d of block %x", i, body.Hash[:])
			}
		}
	}
	// Fill the sender cache of transactions in the block.
	txs := make([]*types.Transaction, len(body.Transactions))
	for i, tx := range body.Transactions {
		if tx.From != nil {
			setSenderFromServer(tx.tx, *tx.From, *body.Hash)
		}
		txs[i] = tx.tx
	}

	return types.NewBlockWithHeader(head).WithBody(
		types.Body{
			Transactions: txs,
			Uncles:       uncles,
			Withdrawals:  body.Withdrawals,
		}), nil
}

// HeaderByHash returns the block header with the given hash.
func (ec *Client) HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error) {
	var head *types.Header
	err := ec.c.CallContext(ctx, &head, "eth_getBlockByHash", hash, false)
	if err == nil && head == nil {
		err = ethereum.NotFound
	}
	return head, err
}

// HeaderByNumber returns a block header from the current canonical chain.
// If `number` is nil, the latest known block header is returned.
//
// Supported special block number tags:
// - `earliest`  : The genesis (earliest) block
// - `latest`    : The most recently included block
// - `safe`      : The latest safe head block
// - `finalized` : The latest finalized block
// - `pending`   : The pending block
//
// Example usage:
//
// ```go
// HeaderByNumber(context.Background(), big.NewInt(int64(rpc.LatestBlockNumber)))
// ```
func (ec *Client) HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error) {
	var head *types.Header
	err := ec.c.CallContext(ctx, &head, "eth_getBlockByNumber", toBlockNumArg(number), false)
	if err == nil && head == nil {
		err = ethereum.NotFound
	}
	return head, err
}

type rpcTransaction struct {
	tx *types.Transaction
	txExtraInfo
}

type txExtraInfo struct {
	BlockNumber *string         `json:"blockNumber,omitempty"`
	BlockHash   *common.Hash    `json:"blockHash,omitempty"`
	From        *common.Address `json:"from,omitempty"`
}

func (tx *rpcTransaction) UnmarshalJSON(msg []byte) error {
	if err := json.Unmarshal(msg, &tx.tx); err != nil {
		return err
	}
	return json.Unmarshal(msg, &tx.txExtraInfo)
}

// TransactionByHash returns the transaction with the given hash.
func (ec *Client) TransactionByHash(ctx context.Context, hash common.Hash) (tx *types.Transaction, isPending bool, err error) {
	var json *rpcTransaction
	err = ec.c.CallContext(ctx, &json, "eth_getTransactionByHash", hash)
	if err != nil {
		return nil, false, err
	} else if json == nil {
		return nil, false, ethereum.NotFound
	} else if _, r, _ := json.tx.RawSignatureValues(); r == nil {
		return nil, false, errors.New("server returned transaction without signature")
	}
	if json.From != nil && json.BlockHash != nil {
		setSenderFromServer(json.tx, *json.From, *json.BlockHash)
	}
	return json.tx, json.BlockNumber == nil, nil
}

// TransactionSender returns the sender address of the given transaction. The transaction
// must be known to the remote node and included in the blockchain at the given block and
// index. The sender is the one derived by the protocol at the time of inclusion.
//
// There is a fast-path for transactions retrieved by TransactionByHash and
// TransactionInBlock. Getting their sender address can be done without an RPC interaction.
func (ec *Client) TransactionSender(ctx context.Context, tx *types.Transaction, block common.Hash, index uint) (common.Address, error) {
	// Try to load the address from the cache.
	sender, err := types.Sender(&senderFromServer{blockhash: block}, tx)
	if err == nil {
		return sender, nil
	}

	// It was not found in cache, ask the server.
	var meta struct {
		Hash common.Hash
		From common.Address
	}
	if err = ec.c.CallContext(ctx, &meta, "eth_getTransactionByBlockHashAndIndex", block, hexutil.Uint64(index)); err != nil {
		return common.Address{}, err
	}
	if meta.Hash == (common.Hash{}) || meta.Hash != tx.Hash() {
		return common.Address{}, errors.New("wrong inclusion block/index")
	}
	return meta.From, nil
}

// TransactionCount returns the total number of transactions in the given block.
func (ec *Client) TransactionCount(ctx context.Context, blockHash common.Hash) (uint, error) {
	var num hexutil.Uint
	err := ec.c.CallContext(ctx, &num, "eth_getBlockTransactionCountByHash", blockHash)
	return uint(num), err
}

// TransactionInBlock returns a single transaction at index in the given block.
func (ec *Client) TransactionInBlock(ctx context.Context, blockHash common.Hash, index uint) (*types.Transaction, error) {
	var json *rpcTransaction
	err := ec.c.CallContext(ctx, &json, "eth_getTransactionByBlockHashAndIndex", blockHash, hexutil.Uint64(index))
	if err != nil {
		return nil, err
	}
	if json == nil {
		return nil, ethereum.NotFound
	} else if _, r, _ := json.tx.RawSignatureValues(); r == nil {
		return nil, errors.New("server returned transaction without signature")
	}
	if json.From != nil && json.BlockHash != nil {
		setSenderFromServer(json.tx, *json.From, *json.BlockHash)
	}
	return json.tx, err
}

// TransactionReceipt returns the receipt of a transaction by transaction hash.
// Note that the receipt is not available for pending transactions.
func (ec *Client) TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
	var r *types.Receipt
	err := ec.c.CallContext(ctx, &r, "eth_getTransactionReceipt", txHash)
	if err == nil && r == nil {
		return nil, ethereum.NotFound
	}
	return r, err
}

// SubscribeTransactionReceipts subscribes to notifications about transaction receipts.
func (ec *Client) SubscribeTransactionReceipts(ctx context.Context, q *ethereum.TransactionReceiptsQuery, ch chan<- []*types.Receipt) (ethereum.Subscription, error) {
	sub, err := ec.c.EthSubscribe(ctx, ch, "transactionReceipts", q)
	if err != nil {
		return nil, err
	}
	return sub, nil
}

// SyncProgress retrieves the current progress of the sync algorithm. If there's
// no sync currently running, it returns nil.
func (ec *Client) SyncProgress(ctx context.Context) (*ethereum.SyncProgress, error) {
	var raw json.RawMessage
	if err := ec.c.CallContext(ctx, &raw, "eth_syncing"); err != nil {
		return nil, err
	}
	// Handle the possible response types
	var syncing bool
	if err := json.Unmarshal(raw, &syncing); err == nil {
		return nil, nil // Not syncing (always false)
	}
	var p *rpcProgress
	if err := json.Unmarshal(raw, &p); err != nil {
		return nil, err
	}
	return p.toSyncProgress(), nil
}

// SubscribeNewHead subscribes to notifications about the current blockchain head
// on the given channel.
func (ec *Client) SubscribeNewHead(ctx context.Context, ch chan<- *types.Header) (ethereum.Subscription, error) {
	sub, err := ec.c.EthSubscribe(ctx, ch, "newHeads")
	if err != nil {
		// Defensively prefer returning nil interface explicitly on error-path, instead
		// of letting default golang behavior wrap it with non-nil interface that stores
		// nil concrete type value.
		return nil, err
	}
	return sub, nil
}

// State Access

// NetworkID returns the network ID for this client.
func (ec *Client) NetworkID(ctx context.Context) (*big.Int, error) {
	version := new(big.Int)
	var ver string
	if err := ec.c.CallContext(ctx, &ver, "net_version"); err != nil {
		return nil, err
	}
	if _, ok := version.SetString(ver, 0); !ok {
		return nil, fmt.Errorf("invalid net_version result %q", ver)
	}
	return version, nil
}

// BalanceAt returns the wei balance of the given account.
// The block number can be nil, in which case the balance is taken from the latest known block.
func (ec *Client) BalanceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (*big.Int, error) {
	var result hexutil.Big
	err := ec.c.CallContext(ctx, &result, "eth_getBalance", account, toBlockNumArg(blockNumber))
	return (*big.Int)(&result), err
}

// BalanceAtHash returns the wei balance of the given account.
func (ec *Client) BalanceAtHash(ctx context.Context, account common.Address, blockHash common.Hash) (*big.Int, error) {
	var result hexutil.Big
	err := ec.c.CallContext(ctx, &result, "eth_getBalance", account, rpc.BlockNumberOrHashWithHash(blockHash, false))
	return (*big.Int)(&result), err
}

// StorageAt returns the value of key in the contract storage of the given account.
// The block number can be nil, in which case the value is taken from the latest known block.
func (ec *Client) StorageAt(ctx context.Context, account common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error) {
	var result hexutil.Bytes
	err := ec.c.CallContext(ctx, &result, "eth_getStorageAt", account, key, toBlockNumArg(blockNumber))
	return result, err
}

// StorageAtHash returns the value of key in the contract storage of the given account.
func (ec *Client) StorageAtHash(ctx context.Context, account common.Address, key common.Hash, blockHash common.Hash) ([]byte, error) {
	var result hexutil.Bytes
	err := ec.c.CallContext(ctx, &result, "eth_getStorageAt", account, key, rpc.BlockNumberOrHashWithHash(blockHash, false))
	return result, err
}

// CodeAt returns the contract code of the given account.
// The block number can be nil, in which case the code is taken from the latest known block.
func (ec *Client) CodeAt(ctx context.Context, account common.Address, blockNumber *big.Int) ([]byte, error) {
	var result hexutil.Bytes
	err := ec.c.CallContext(ctx, &result, "eth_getCode", account, toBlockNumArg(blockNumber))
	return result, err
}

// CodeAtHash returns the contract code of the given account.
func (ec *Client) CodeAtHash(ctx context.Context, account common.Address, blockHash common.Hash) ([]byte, error) {
	var result hexutil.Bytes
	err := ec.c.CallContext(ctx, &result, "eth_getCode", account, rpc.BlockNumberOrHashWithHash(blockHash, false))
	return result, err
}

// NonceAt returns the account nonce of the given account.
// The block number can be nil, in which case the nonce is taken from the latest known block.
func (ec *Client) NonceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (uint64, error) {
	var result hexutil.Uint64
	err := ec.c.CallContext(ctx, &result, "eth_getTransactionCount", account, toBlockNumArg(blockNumber))
	return uint64(result), err
}

// NonceAtHash returns the account nonce of the given account.
func (ec *Client) NonceAtHash(ctx context.Context, account common.Address, blockHash common.Hash) (uint64, error) {
	var result hexutil.Uint64
	err := ec.c.CallContext(ctx, &result, "eth_getTransactionCount", account, rpc.BlockNumberOrHashWithHash(blockHash, false))
	return uint64(result), err
}

// Filters

// FilterLogs executes a filter query.
func (ec *Client) FilterLogs(ctx context.Context, q ethereum.FilterQuery) ([]types.Log, error) {
	var result []types.Log
	arg, err := toFilterArg(q)
	if err != nil {
		return nil, err
	}
	err = ec.c.CallContext(ctx, &result, "eth_getLogs", arg)
	return result, err
}

// SubscribeFilterLogs subscribes to the results of a streaming filter query.
func (ec *Client) SubscribeFilterLogs(ctx context.Context, q ethereum.FilterQuery, ch chan<- types.Log) (ethereum.Subscription, error) {
	arg, err := toFilterArg(q)
	if err != nil {
		return nil, err
	}
	sub, err := ec.c.EthSubscribe(ctx, ch, "logs", arg)
	if err != nil {
		// Defensively prefer returning nil interface explicitly on error-path, instead
		// of letting default golang behavior wrap it with non-nil interface that stores
		// nil concrete type value.
		return nil, err
	}
	return sub, nil
}

func toFilterArg(q ethereum.FilterQuery) (interface{}, error) {
	arg := map[string]interface{}{}
	if q.Addresses != nil {
		arg["address"] = q.Addresses
	}
	if q.Topics != nil {
		arg["topics"] = q.Topics
	}
	if q.BlockHash != nil {
		arg["blockHash"] = *q.BlockHash
		if q.FromBlock != nil || q.ToBlock != nil {
			return nil, errors.New("cannot specify both BlockHash and FromBlock/ToBlock")
		}
	} else {
		if q.FromBlock == nil {
			arg["fromBlock"] = "0x0"
		} else {
			arg["fromBlock"] = toBlockNumArg(q.FromBlock)
		}
		arg["toBlock"] = toBlockNumArg(q.ToBlock)
	}
	return arg, nil
}

// Pending State

// PendingBalanceAt returns the wei balance of the given account in the pending state.
func (ec *Client) PendingBalanceAt(ctx context.Context, account common.Address) (*big.Int, error) {
	var result hexutil.Big
	err := ec.c.CallContext(ctx, &result, "eth_getBalance", account, "pending")
	return (*big.Int)(&result), err
}

// PendingStorageAt returns the value of key in the contract storage of the given account in the pending state.
func (ec *Client) PendingStorageAt(ctx context.Context, account common.Address, key common.Hash) ([]byte, error) {
	var result hexutil.Bytes
	err := ec.c.CallContext(ctx, &result, "eth_getStorageAt", account, key, "pending")
	return result, err
}

// PendingCodeAt returns the contract code of the given account in the pending state.
func (ec *Client) PendingCodeAt(ctx context.Context, account common.Address) ([]byte, error) {
	var result hexutil.Bytes
	err := ec.c.CallContext(ctx, &result, "eth_getCode", account, "pending")
	return result, err
}

// PendingNonceAt returns the account nonce of the given account in the pending state.
// This is the nonce that should be used for the next transaction.
func (ec *Client) PendingNonceAt(ctx context.Context, account common.Address) (uint64, error) {
	var result hexutil.Uint64
	err := ec.c.CallContext(ctx, &result, "eth_getTransactionCount", account, "pending")
	return uint64(result), err
}

// PendingTransactionCount returns the total number of transactions in the pending state.
func (ec *Client) PendingTransactionCount(ctx context.Context) (uint, error) {
	var num hexutil.Uint
	err := ec.c.CallContext(ctx, &num, "eth_getBlockTransactionCountByNumber", "pending")
	return uint(num), err
}

// Contract Calling

// CallContract executes a message call transaction, which is directly executed in the VM
// of the node, but never mined into the blockchain.
//
// blockNumber selects the block height at which the call runs. It can be nil, in which
// case the code is taken from the latest known block. Note that state from very old
// blocks might not be available.
func (ec *Client) CallContract(ctx context.Context, msg ethereum.CallMsg, blockNumber *big.Int) ([]byte, error) {
	var hex hexutil.Bytes
	err := ec.c.CallContext(ctx, &hex, "eth_call", toCallArg(msg), toBlockNumArg(blockNumber))
	if err != nil {
		return nil, err
	}
	return hex, nil
}

// CallContractAtHash is almost the same as CallContract except that it selects
// the block by block hash instead of block height.
func (ec *Client) CallContractAtHash(ctx context.Context, msg ethereum.CallMsg, blockHash common.Hash) ([]byte, error) {
	var hex hexutil.Bytes
	err := ec.c.CallContext(ctx, &hex, "eth_call", toCallArg(msg), rpc.BlockNumberOrHashWithHash(blockHash, false))
	if err != nil {
		return nil, err
	}
	return hex, nil
}

// PendingCallContract executes a message call transaction using the EVM.
// The state seen by the contract call is the pending state.
func (ec *Client) PendingCallContract(ctx context.Context, msg ethereum.CallMsg) ([]byte, error) {
	var hex hexutil.Bytes
	err := ec.c.CallContext(ctx, &hex, "eth_call", toCallArg(msg), "pending")
	if err != nil {
		return nil, err
	}
	return hex, nil
}

// SuggestGasPrice retrieves the currently suggested gas price to allow a timely
// execution of a transaction.
func (ec *Client) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
	var hex hexutil.Big
	if err := ec.c.CallContext(ctx, &hex, "eth_gasPrice"); err != nil {
		return nil, err
	}
	return (*big.Int)(&hex), nil
}

// SuggestGasTipCap retrieves the currently suggested gas tip cap after 1559 to
// allow a timely execution of a transaction.
func (ec *Client) SuggestGasTipCap(ctx context.Context) (*big.Int, error) {
	var hex hexutil.Big
	if err := ec.c.CallContext(ctx, &hex, "eth_maxPriorityFeePerGas"); err != nil {
		return nil, err
	}
	return (*big.Int)(&hex), nil
}

// BlobBaseFee retrieves the current blob base fee.
func (ec *Client) BlobBaseFee(ctx context.Context) (*big.Int, error) {
	var hex hexutil.Big
	if err := ec.c.CallContext(ctx, &hex, "eth_blobBaseFee"); err != nil {
		return nil, err
	}
	return (*big.Int)(&hex), nil
}

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

// FeeHistory retrieves the fee market history.
func (ec *Client) FeeHistory(ctx context.Context, blockCount uint64, lastBlock *big.Int, rewardPercentiles []float64) (*ethereum.FeeHistory, error) {
	var res feeHistoryResultMarshaling
	if err := ec.c.CallContext(ctx, &res, "eth_feeHistory", hexutil.Uint(blockCount), toBlockNumArg(lastBlock), rewardPercentiles); err != nil {
		return nil, err
	}
	reward := make([][]*big.Int, len(res.Reward))
	for i, r := range res.Reward {
		reward[i] = make([]*big.Int, len(r))
		for j, r := range r {
			reward[i][j] = (*big.Int)(r)
		}
	}
	baseFee := make([]*big.Int, len(res.BaseFee))
	for i, b := range res.BaseFee {
		baseFee[i] = (*big.Int)(b)
	}
	return &ethereum.FeeHistory{
		OldestBlock:  (*big.Int)(res.OldestBlock),
		Reward:       reward,
		BaseFee:      baseFee,
		GasUsedRatio: res.GasUsedRatio,
	}, nil
}

// EstimateGas tries to estimate the gas needed to execute a specific transaction based on
// the current state of the backend blockchain. There is no guarantee that this is the
// true gas limit requirement as other transactions may be added or removed by miners, but
// it should provide a basis for setting a reasonable default.
//
// Note that the state used by this method is implementation-defined by the remote RPC
// server, but it's reasonable to assume that it will either be the pending or latest
// state.
func (ec *Client) EstimateGas(ctx context.Context, msg ethereum.CallMsg) (uint64, error) {
	var hex hexutil.Uint64
	err := ec.c.CallContext(ctx, &hex, "eth_estimateGas", toCallArg(msg))
	if err != nil {
		return 0, err
	}
	return uint64(hex), nil
}

// EstimateGasAtBlock is almost the same as EstimateGas except that it selects the block height
// instead of using the remote RPC's default state for gas estimation.
func (ec *Client) EstimateGasAtBlock(ctx context.Context, msg ethereum.CallMsg, blockNumber *big.Int) (uint64, error) {
	var hex hexutil.Uint64
	err := ec.c.CallContext(ctx, &hex, "eth_estimateGas", toCallArg(msg), toBlockNumArg(blockNumber))
	if err != nil {
		return 0, err
	}
	return uint64(hex), nil
}

// EstimateGasAtBlockHash is almost the same as EstimateGas except that it selects the block
// hash instead of using the remote RPC's default state for gas estimation.
func (ec *Client) EstimateGasAtBlockHash(ctx context.Context, msg ethereum.CallMsg, blockHash common.Hash) (uint64, error) {
	var hex hexutil.Uint64
	err := ec.c.CallContext(ctx, &hex, "eth_estimateGas", toCallArg(msg), rpc.BlockNumberOrHashWithHash(blockHash, false))
	if err != nil {
		return 0, err
	}
	return uint64(hex), nil
}

// SendTransaction injects a signed transaction into the pending pool for execution.
//
// If the transaction was a contract creation use the TransactionReceipt method to get the
// contract address after the transaction has been mined.
func (ec *Client) SendTransaction(ctx context.Context, tx *types.Transaction) error {
	data, err := tx.MarshalBinary()
	if err != nil {
		return err
	}
	return ec.c.CallContext(ctx, nil, "eth_sendRawTransaction", hexutil.Encode(data))
}

// SendTransactionSync submits a signed tx and waits for a receipt (or until
// the optional timeout elapses on the server side). If timeout == 0, the server
// uses its default.
func (ec *Client) SendTransactionSync(
	ctx context.Context,
	tx *types.Transaction,
	timeout *time.Duration,
) (*types.Receipt, error) {
	raw, err := tx.MarshalBinary()
	if err != nil {
		return nil, err
	}
	return ec.SendRawTransactionSync(ctx, raw, timeout)
}

func (ec *Client) SendRawTransactionSync(
	ctx context.Context,
	rawTx []byte,
	timeout *time.Duration,
) (*types.Receipt, error) {
	var ms *uint64
	if timeout != nil {
		msInt := timeout.Milliseconds()
		if msInt > 0 {
			d := uint64(msInt)
			ms = &d
		}
	}
	var receipt types.Receipt
	if err := ec.c.CallContext(ctx, &receipt, "eth_sendRawTransactionSync", hexutil.Bytes(rawTx), ms); err != nil {
		return nil, err
	}
	return &receipt, nil
}

// RevertErrorData returns the 'revert reason' data of a contract call.
//
// This can be used with CallContract and EstimateGas, and only when the server is Geth.
func RevertErrorData(err error) ([]byte, bool) {
	var ec rpc.Error
	var ed rpc.DataError
	if errors.As(err, &ec) && errors.As(err, &ed) && ec.ErrorCode() == 3 {
		if eds, ok := ed.ErrorData().(string); ok {
			revertData, err := hexutil.Decode(eds)
			if err == nil {
				return revertData, true
			}
		}
	}
	return nil, false
}

func toBlockNumArg(number *big.Int) string {
	if number == nil {
		return "latest"
	}
	if number.Sign() >= 0 {
		return hexutil.EncodeBig(number)
	}
	// It's negative.
	if number.IsInt64() {
		return rpc.BlockNumber(number.Int64()).String()
	}
	// It's negative and large, which is invalid.
	return fmt.Sprintf("<invalid %d>", number)
}

func toCallArg(msg ethereum.CallMsg) interface{} {
	arg := map[string]interface{}{
		"from": msg.From,
		"to":   msg.To,
	}
	if len(msg.Data) > 0 {
		arg["input"] = hexutil.Bytes(msg.Data)
	}
	if msg.Value != nil {
		arg["value"] = (*hexutil.Big)(msg.Value)
	}
	if msg.Gas != 0 {
		arg["gas"] = hexutil.Uint64(msg.Gas)
	}
	if msg.GasPrice != nil {
		arg["gasPrice"] = (*hexutil.Big)(msg.GasPrice)
	}
	if msg.GasFeeCap != nil {
		arg["maxFeePerGas"] = (*hexutil.Big)(msg.GasFeeCap)
	}
	if msg.GasTipCap != nil {
		arg["maxPriorityFeePerGas"] = (*hexutil.Big)(msg.GasTipCap)
	}
	if msg.AccessList != nil {
		arg["accessList"] = msg.AccessList
	}
	if msg.BlobGasFeeCap != nil {
		arg["maxFeePerBlobGas"] = (*hexutil.Big)(msg.BlobGasFeeCap)
	}
	if msg.BlobHashes != nil {
		arg["blobVersionedHashes"] = msg.BlobHashes
	}
	if msg.AuthorizationList != nil {
		arg["authorizationList"] = msg.AuthorizationList
	}
	return arg
}

// rpcProgress is a copy of SyncProgress with hex-encoded fields.
type rpcProgress struct {
	StartingBlock hexutil.Uint64
	CurrentBlock  hexutil.Uint64
	HighestBlock  hexutil.Uint64

	PulledStates hexutil.Uint64
	KnownStates  hexutil.Uint64

	SyncedAccounts         hexutil.Uint64
	SyncedAccountBytes     hexutil.Uint64
	SyncedBytecodes        hexutil.Uint64
	SyncedBytecodeBytes    hexutil.Uint64
	SyncedStorage          hexutil.Uint64
	SyncedStorageBytes     hexutil.Uint64
	HealedTrienodes        hexutil.Uint64
	HealedTrienodeBytes    hexutil.Uint64
	HealedBytecodes        hexutil.Uint64
	HealedBytecodeBytes    hexutil.Uint64
	HealingTrienodes       hexutil.Uint64
	HealingBytecode        hexutil.Uint64
	TxIndexFinishedBlocks  hexutil.Uint64
	TxIndexRemainingBlocks hexutil.Uint64
	StateIndexRemaining    hexutil.Uint64
}

func (p *rpcProgress) toSyncProgress() *ethereum.SyncProgress {
	if p == nil {
		return nil
	}
	return &ethereum.SyncProgress{
		StartingBlock:          uint64(p.StartingBlock),
		CurrentBlock:           uint64(p.CurrentBlock),
		HighestBlock:           uint64(p.HighestBlock),
		PulledStates:           uint64(p.PulledStates),
		KnownStates:            uint64(p.KnownStates),
		SyncedAccounts:         uint64(p.SyncedAccounts),
		SyncedAccountBytes:     uint64(p.SyncedAccountBytes),
		SyncedBytecodes:        uint64(p.SyncedBytecodes),
		SyncedBytecodeBytes:    uint64(p.SyncedBytecodeBytes),
		SyncedStorage:          uint64(p.SyncedStorage),
		SyncedStorageBytes:     uint64(p.SyncedStorageBytes),
		HealedTrienodes:        uint64(p.HealedTrienodes),
		HealedTrienodeBytes:    uint64(p.HealedTrienodeBytes),
		HealedBytecodes:        uint64(p.HealedBytecodes),
		HealedBytecodeBytes:    uint64(p.HealedBytecodeBytes),
		HealingTrienodes:       uint64(p.HealingTrienodes),
		HealingBytecode:        uint64(p.HealingBytecode),
		TxIndexFinishedBlocks:  uint64(p.TxIndexFinishedBlocks),
		TxIndexRemainingBlocks: uint64(p.TxIndexRemainingBlocks),
		StateIndexRemaining:    uint64(p.StateIndexRemaining),
	}
}

// SimulateOptions represents the options for eth_simulateV1.
type SimulateOptions struct {
	BlockStateCalls        []SimulateBlock `json:"blockStateCalls"`
	TraceTransfers         bool            `json:"traceTransfers"`
	Validation             bool            `json:"validation"`
	ReturnFullTransactions bool            `json:"returnFullTransactions"`
}

// SimulateBlock represents a batch of calls to be simulated.
type SimulateBlock struct {
	BlockOverrides *ethereum.BlockOverrides                    `json:"blockOverrides,omitempty"`
	StateOverrides map[common.Address]ethereum.OverrideAccount `json:"stateOverrides,omitempty"`
	Calls          []ethereum.CallMsg                          `json:"calls"`
}

// MarshalJSON implements json.Marshaler for SimulateBlock.
func (s SimulateBlock) MarshalJSON() ([]byte, error) {
	type Alias struct {
		BlockOverrides *ethereum.BlockOverrides                    `json:"blockOverrides,omitempty"`
		StateOverrides map[common.Address]ethereum.OverrideAccount `json:"stateOverrides,omitempty"`
		Calls          []interface{}                               `json:"calls"`
	}
	calls := make([]interface{}, len(s.Calls))
	for i, call := range s.Calls {
		calls[i] = toCallArg(call)
	}
	return json.Marshal(Alias{
		BlockOverrides: s.BlockOverrides,
		StateOverrides: s.StateOverrides,
		Calls:          calls,
	})
}

//go:generate go run github.com/fjl/gencodec -type SimulateCallResult -field-override simulateCallResultMarshaling -out gen_simulate_call_result.go

// SimulateCallResult is the result of a simulated call.
type SimulateCallResult struct {
	ReturnValue []byte       `json:"returnData"`
	Logs        []*types.Log `json:"logs"`
	GasUsed     uint64       `json:"gasUsed"`
	Status      uint64       `json:"status"`
	Error       *CallError   `json:"error,omitempty"`
}

type simulateCallResultMarshaling struct {
	ReturnValue hexutil.Bytes
	GasUsed     hexutil.Uint64
	Status      hexutil.Uint64
}

// CallError represents an error from a simulated call.
type CallError struct {
	Code    int    `json:"code"`
	Message string `json:"message"`
	Data    string `json:"data,omitempty"`
}

//go:generate go run github.com/fjl/gencodec -type SimulateBlockResult -field-override simulateBlockResultMarshaling -out gen_simulate_block_result.go

// SimulateBlockResult represents the result of a simulated block.
type SimulateBlockResult struct {
	Number        *big.Int             `json:"number"`
	Hash          common.Hash          `json:"hash"`
	Timestamp     uint64               `json:"timestamp"`
	GasLimit      uint64               `json:"gasLimit"`
	GasUsed       uint64               `json:"gasUsed"`
	FeeRecipient  common.Address       `json:"miner"`
	BaseFeePerGas *big.Int             `json:"baseFeePerGas,omitempty"`
	Calls         []SimulateCallResult `json:"calls"`
}

type simulateBlockResultMarshaling struct {
	Number        *hexutil.Big
	Timestamp     hexutil.Uint64
	GasLimit      hexutil.Uint64
	GasUsed       hexutil.Uint64
	BaseFeePerGas *hexutil.Big
}

// SimulateV1 executes transactions on top of a base state.
func (ec *Client) SimulateV1(ctx context.Context, opts SimulateOptions, blockNrOrHash *rpc.BlockNumberOrHash) ([]SimulateBlockResult, error) {
	var result []SimulateBlockResult
	err := ec.c.CallContext(ctx, &result, "eth_simulateV1", opts, blockNrOrHash)
	return result, err
}
