contract_stub.go

package swan

import (
	"context"
	"crypto/ecdsa"
	"fmt"
	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/ethclient"
	"math/big"
	"strings"
)

func privateKeyToPublicKey(privateKey string) (common.Address, error) {
	if len(strings.TrimSpace(privateKey)) == 0 {
		return common.Address{}, fmt.Errorf("wallet address private key must be not empty")
	}

	privateK, err := crypto.HexToECDSA(privateKey)
	if err != nil {
		return common.Address{}, fmt.Errorf("parses private key error: %+v", err)
	}

	publicKey := privateK.Public()
	publicKeyECDSA, ok := publicKey.(*ecdsa.PublicKey)
	if !ok {
		return common.Address{}, fmt.Errorf("cannot assert type: publicKey is not of type *ecdsa.PublicKey")
	}
	return crypto.PubkeyToAddress(*publicKeyECDSA), nil
}

func CreateTransactOpts(client *ethclient.Client, privateKey string) (*bind.TransactOpts, error) {
	if privateKey == "" {
		return nil, fmt.Errorf("required privateKey field")
	}

	publicAddress, err := privateKeyToPublicKey(privateKey)

	nonce, err := client.PendingNonceAt(context.Background(), publicAddress)
	if err != nil {
		return nil, fmt.Errorf("failed to get nonce error: %v", err)
	}

	suggestGasPrice, err := client.SuggestGasPrice(context.Background())
	if err != nil {
		return nil, fmt.Errorf("failed to retrieves the currently suggested gas price, error: %v", err)
	}

	chainId, err := client.ChainID(context.Background())
	if err != nil {
		return nil, fmt.Errorf("failed to get networkId, error: %v", err)
	}

	privateK, err := crypto.HexToECDSA(privateKey)
	if err != nil {
		return nil, fmt.Errorf("parses private key error: %+v", err)
	}

	txOptions, err := bind.NewKeyedTransactorWithChainID(privateK, chainId)
	if err != nil {
		return nil, fmt.Errorf("failed to create transaction opts, error: %v", err)
	}
	txOptions.Nonce = big.NewInt(int64(nonce))
	suggestGasPrice = suggestGasPrice.Mul(suggestGasPrice, big.NewInt(3))
	suggestGasPrice = suggestGasPrice.Div(suggestGasPrice, big.NewInt(2))
	txOptions.GasFeeCap = suggestGasPrice
	txOptions.Context = context.Background()
	return txOptions, nil
}