util.go

package calls

import (
	"errors"
	"math"
	gomath "math"
	"math/big"
	"strings"

	"github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/crypto"
)

func GetSolidityFunctionSig(in []byte) [4]byte {
	var res [4]byte
	hash := crypto.Keccak256Hash(in)
	copy(res[:], hash[:])
	return res
}

func SliceTo32Bytes(in []byte) [32]byte {
	var res [32]byte
	copy(res[:], in)
	return res
}

// ToCallArg is the function that converts ethereum.CallMsg into more abstract map
// This is done for matter of  making EVMClient more abstract since some go-ethereum forks uses different messages types
func ToCallArg(msg ethereum.CallMsg) map[string]interface{} {
	arg := map[string]interface{}{
		"from": msg.From,
		"to":   msg.To,
	}
	if len(msg.Data) > 0 {
		arg["data"] = 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)
	}
	return arg
}

// UserAmountToWei converts decimal user friendly representation of token amount to 'Wei' representation with provided amount of decimal places
// eg UserAmountToWei(1, 5) => 100000
func UserAmountToWei(amount string, decimal *big.Int) (*big.Int, error) {
	amountFloat, ok := big.NewFloat(0).SetString(amount)
	if !ok {
		return nil, errors.New("wrong amount format")
	}
	ethValueFloat := new(big.Float).Mul(amountFloat, big.NewFloat(math.Pow10(int(decimal.Int64()))))
	ethValueFloatString := strings.Split(ethValueFloat.Text('f', int(decimal.Int64())), ".")

	i, ok := big.NewInt(0).SetString(ethValueFloatString[0], 10)
	if !ok {
		return nil, errors.New(ethValueFloat.Text('f', int(decimal.Int64())))
	}

	return i, nil
}

func WeiAmountToUser(amount *big.Int, decimals *big.Int) (*big.Float, error) {
	amountFloat, ok := big.NewFloat(0).SetString(amount.String())
	if !ok {
		return nil, errors.New("wrong amount format")
	}
	return new(big.Float).Quo(amountFloat, big.NewFloat(gomath.Pow10(int(decimals.Int64())))), nil
}