status-im/status-go

package transactions

import (
    "context"
    "math/big"

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

    "github.com/status-im/status-go/eth-node/types"

    "github.com/status-im/status-go/rpc"
)

// rpcWrapper wraps provides convenient interface for ethereum RPC APIs we need for sending transactions
type rpcWrapper struct {
    RPCClient *rpc.Client
    chainID   uint64
}

func newRPCWrapper(client *rpc.Client, chainID uint64) *rpcWrapper {
    return &rpcWrapper{RPCClient: client, chainID: chainID}
}

// 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 (w *rpcWrapper) PendingNonceAt(ctx context.Context, account common.Address) (uint64, error) {
    var result hexutil.Uint64
    err := w.RPCClient.CallContext(ctx, &result, w.chainID, "eth_getTransactionCount", account, "pending")
    return uint64(result), err
}

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

// EstimateGas tries to estimate the gas needed to execute a specific transaction based on
// the current pending 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.
func (w *rpcWrapper) EstimateGas(ctx context.Context, msg ethereum.CallMsg) (uint64, error) {
    var hex hexutil.Uint64
    err := w.RPCClient.CallContext(ctx, &hex, w.chainID, "eth_estimateGas", toCallArg(msg))
    if err != nil {
        return 0, err
    }
    return uint64(hex), nil
}

// Does the `eth_sendRawTransaction` call with the given raw transaction hex string.
func (w *rpcWrapper) SendRawTransaction(ctx context.Context, rawTx string) error {
    return w.RPCClient.CallContext(ctx, nil, w.chainID, "eth_sendRawTransaction", rawTx)
}

// 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 (w *rpcWrapper) SendTransaction(ctx context.Context, tx *gethtypes.Transaction) error {
    data, err := tx.MarshalBinary()
    if err != nil {
        return err
    }
    return w.SendRawTransaction(ctx, types.EncodeHex(data))
}

func toCallArg(msg ethereum.CallMsg) interface{} {
    arg := map[string]interface{}{
        "from": msg.From,
        "to":   msg.To,
    }
    if len(msg.Data) > 0 {
        arg["data"] = types.HexBytes(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)
    }
    return arg
}