wallet/pkg/eth/eth_transaction.go

package eth

import (
	"context"
	"fmt"
	"math/big"
	"strings"

	"github.com/ethereum/go-ethereum/accounts/abi"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/ethclient"
)

func (e *EthAccount) SignTx(tx *types.Transaction) (*types.Transaction, error) {
	client, err := ethclient.Dial(ethNode.rpcNode)
	if err != nil {
		return nil, err
	}

	chainID, err := client.NetworkID(context.Background())
	if err != nil {
		return nil, err
	}

	signedTx, err := types.SignTx(tx, types.LatestSignerForChainID(chainID), e.PrivateKey())
	if err != nil {
		return nil, err
	}

	return signedTx, nil
}

func GetTransactionByHash(hash string) (*types.Receipt, error) {
	fmt.Println("GetTransactionByHash", hash)
	client, err := ethclient.Dial(ethNode.rpcNode)
	if err != nil {
		return nil, err
	}
	_byte, err := common.ParseHexOrString(hash)
	if err != nil {
		return nil, err
	}
	_hash := common.BytesToHash(_byte)
	tx, err := client.TransactionReceipt(context.Background(), _hash)
	if err != nil {
		return nil, err
	}
	return tx, nil
}

func GetTransactionReceipt(txHash common.Hash) *types.Receipt {
	client, err := ethclient.Dial(ethNode.rpcNode)
	if err != nil {
		return nil
	}
	receipt, err := client.TransactionReceipt(context.Background(), txHash)
	if err != nil {
		return nil
	}
	return receipt
}

type ERC20TransferEvent struct {
	From  string
	To    string
	Value string
}

func decodeTransactionLogs(receipt *types.Receipt, contractABI *abi.ABI) ERC20TransferEvent {

	for _, vLog := range receipt.Logs {
		// topic[0] is the event name
		event, err := contractABI.EventByID(vLog.Topics[0])
		if err != nil {
			return ERC20TransferEvent{}
		}

		events := map[string]bool{
			"Transfer":     true,
			"TransferFrom": true,
		}

		if !events[event.Name] {
			continue
		}
		// topic[1:] is other indexed params in event
		ev := ERC20TransferEvent{}
		if len(vLog.Topics) > 1 {
			ev.From = common.HexToAddress(vLog.Topics[1].Hex()).String()
			ev.To = common.HexToAddress(vLog.Topics[2].Hex()).String()
		}

		if len(vLog.Data) > 0 {
			//fmt.Printf("Log Data in Hex: %s\n", hex.EncodeToString(vLog.Data))
			outputDataMap := make(map[string]interface{})
			err = contractABI.UnpackIntoMap(outputDataMap, event.Name, vLog.Data)
			if err == nil {
				ev.Value = outputDataMap["_value"].(*big.Int).String()
			}
		}
		//fmt.Println(">>>>>", ev)
		return ev
	}
	return ERC20TransferEvent{}
}

func GetErc20Tranfer(txHash common.Hash) ERC20TransferEvent {
	abi, err := abi.JSON(strings.NewReader(COMMON_ABI))
	receipt := GetTransactionReceipt(txHash)
	if receipt == nil || len(receipt.Logs) == 0 || err != nil {
		return ERC20TransferEvent{}
	}
	return decodeTransactionLogs(receipt, &abi)
}

type TransactionData = map[string]interface{}

func DecodeERC20Transfer(data []byte) (tx TransactionData, err error) {
	abi, err := abi.JSON(strings.NewReader(COMMON_ABI))
	if err != nil {
		return nil, err
	}
	tx = make(TransactionData)
	if len(data) < 4 {
		return nil, nil
	}
	methodSigData := data[:4]
	method, err := abi.MethodById(methodSigData)
	if err != nil {
		return nil, err
	}
	inputsSigData := data[4:]
	if err := method.Inputs.UnpackIntoMap(tx, inputsSigData); err != nil {
		return nil, err
	}
	return tx, nil
}