package ethereum_utils

import (
    "math/big"
    "reflect"
    "regexp"
    "strconv"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/common/hexutil"
    "github.com/shopspring/decimal"
)

// IsValidAddress validate hex address
func IsValidAddress(iaddress interface{}) bool {
    re := regexp.MustCompile("^0x[0-9a-fA-F]{40}$")
    switch v := iaddress.(type) {
    case string:
        return re.MatchString(v)
    case common.Address:
        return re.MatchString(v.Hex())
    default:
        return false
    }
}

// IsZeroAddress validate if it's a 0 address
func IsZeroAddress(iaddress interface{}) bool {
    var address common.Address
    switch v := iaddress.(type) {
    case string:
        address = common.HexToAddress(v)
    case common.Address:
        address = v
    default:
        return false
    }

    zeroAddressBytes := common.FromHex("0x0000000000000000000000000000000000000000")
    addressBytes := address.Bytes()
    return reflect.DeepEqual(addressBytes, zeroAddressBytes)
}

// ToDecimal wei to decimals
func ToDecimal(ivalue interface{}, decimals int) decimal.Decimal {
    value := new(big.Int)
    switch v := ivalue.(type) {
    case string:
        value.SetString(v, 10)
    case *big.Int:
        value = v
    }

    mul := decimal.NewFromFloat(float64(10)).Pow(decimal.NewFromFloat(float64(decimals)))
    num, _ := decimal.NewFromString(value.String())
    result := num.Div(mul)

    return result
}

// ToWei decimals to wei
func ToWei(iamount interface{}, decimals int) *big.Int {
    amount := decimal.NewFromFloat(0)
    switch v := iamount.(type) {
    case string:
        amount, _ = decimal.NewFromString(v)
    case float64:
        amount = decimal.NewFromFloat(v)
    case int64:
        amount = decimal.NewFromFloat(float64(v))
    case decimal.Decimal:
        amount = v
    case *decimal.Decimal:
        amount = *v
    }

    mul := decimal.NewFromFloat(float64(10)).Pow(decimal.NewFromFloat(float64(decimals)))
    result := amount.Mul(mul)

    wei := new(big.Int)
    wei.SetString(result.String(), 10)

    return wei
}

// CalcGasCost calculate gas cost given gas limit (units) and gas price (wei)
func CalcGasCost(gasLimit uint64, gasPrice *big.Int) *big.Int {
    gasLimitBig := big.NewInt(int64(gasLimit))
    return gasLimitBig.Mul(gasLimitBig, gasPrice)
}

// SigRSV signatures R S V returned as arrays
func SigRSV(isig interface{}) ([32]byte, [32]byte, uint8) {
    var sig []byte
    switch v := isig.(type) {
    case []byte:
        sig = v
    case string:
        sig, _ = hexutil.Decode(v)
    }

    sigstr := common.Bytes2Hex(sig)
    rS := sigstr[0:64]
    sS := sigstr[64:128]
    R := [32]byte{}
    S := [32]byte{}
    copy(R[:], common.FromHex(rS))
    copy(S[:], common.FromHex(sS))
    vStr := sigstr[128:130]
    vI, _ := strconv.Atoi(vStr)
    V := uint8(vI + 27)

    return R, S, V
}