metamask-extension/ui/pages/send/send.utils.js

import abi from 'ethereumjs-abi';
import {
  addCurrencies,
  conversionUtil,
  conversionGTE,
  multiplyCurrencies,
  conversionGreaterThan,
  conversionLessThan,
} from '../../helpers/utils/conversion-util';

import { calcTokenAmount } from '../../helpers/utils/token-util';
import { addHexPrefix } from '../../../app/scripts/lib/util';

import { TOKEN_TRANSFER_FUNCTION_SIGNATURE } from './send.constants';

export {
  addGasBuffer,
  calcGasTotal,
  generateTokenTransferData,
  isBalanceSufficient,
  isTokenBalanceSufficient,
  ellipsify,
};

function calcGasTotal(gasLimit = '0', gasPrice = '0') {
  return multiplyCurrencies(gasLimit, gasPrice, {
    toNumericBase: 'hex',
    multiplicandBase: 16,
    multiplierBase: 16,
  });
}

function isBalanceSufficient({
  amount = '0x0',
  balance = '0x0',
  conversionRate = 1,
  gasTotal = '0x0',
  primaryCurrency,
}) {
  const totalAmount = addCurrencies(amount, gasTotal, {
    aBase: 16,
    bBase: 16,
    toNumericBase: 'hex',
  });

  const balanceIsSufficient = conversionGTE(
    {
      value: balance,
      fromNumericBase: 'hex',
      fromCurrency: primaryCurrency,
      conversionRate,
    },
    {
      value: totalAmount,
      fromNumericBase: 'hex',
      conversionRate,
      fromCurrency: primaryCurrency,
    },
  );

  return balanceIsSufficient;
}

function isTokenBalanceSufficient({ amount = '0x0', tokenBalance, decimals }) {
  const amountInDec = conversionUtil(amount, {
    fromNumericBase: 'hex',
  });

  const tokenBalanceIsSufficient = conversionGTE(
    {
      value: tokenBalance,
      fromNumericBase: 'hex',
    },
    {
      value: calcTokenAmount(amountInDec, decimals),
    },
  );

  return tokenBalanceIsSufficient;
}

function addGasBuffer(
  initialGasLimitHex,
  blockGasLimitHex,
  bufferMultiplier = 1.5,
) {
  const upperGasLimit = multiplyCurrencies(blockGasLimitHex, 0.9, {
    toNumericBase: 'hex',
    multiplicandBase: 16,
    multiplierBase: 10,
    numberOfDecimals: '0',
  });
  const bufferedGasLimit = multiplyCurrencies(
    initialGasLimitHex,
    bufferMultiplier,
    {
      toNumericBase: 'hex',
      multiplicandBase: 16,
      multiplierBase: 10,
      numberOfDecimals: '0',
    },
  );

  // if initialGasLimit is above blockGasLimit, dont modify it
  if (
    conversionGreaterThan(
      { value: initialGasLimitHex, fromNumericBase: 'hex' },
      { value: upperGasLimit, fromNumericBase: 'hex' },
    )
  ) {
    return initialGasLimitHex;
  }
  // if bufferedGasLimit is below blockGasLimit, use bufferedGasLimit
  if (
    conversionLessThan(
      { value: bufferedGasLimit, fromNumericBase: 'hex' },
      { value: upperGasLimit, fromNumericBase: 'hex' },
    )
  ) {
    return bufferedGasLimit;
  }
  // otherwise use blockGasLimit
  return upperGasLimit;
}

function generateTokenTransferData({
  toAddress = '0x0',
  amount = '0x0',
  sendToken,
}) {
  if (!sendToken) {
    return undefined;
  }
  return (
    TOKEN_TRANSFER_FUNCTION_SIGNATURE +
    Array.prototype.map
      .call(
        abi.rawEncode(
          ['address', 'uint256'],
          [toAddress, addHexPrefix(amount)],
        ),
        (x) => `00${x.toString(16)}`.slice(-2),
      )
      .join('')
  );
}

function ellipsify(text, first = 6, last = 4) {
  return `${text.slice(0, first)}...${text.slice(-last)}`;
}