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const ethUtil = require('ethereumjs-util')
const assert = require('assert')
const BN = require('bn.js')
const {
ENVIRONMENT_TYPE_POPUP,
ENVIRONMENT_TYPE_NOTIFICATION,
ENVIRONMENT_TYPE_FULLSCREEN,
} = require('./enums')
/**
* Generates an example stack trace
*
* @returns {string} A stack trace
*
*/
function getStack () {
const stack = new Error('Stack trace generator - not an error').stack
return stack
}
/**
* Used to determine the window type through which the app is being viewed.
* - 'popup' refers to the extension opened through the browser app icon (in top right corner in chrome and firefox)
* - 'responsive' refers to the main browser window
* - 'notification' refers to the popup that appears in its own window when taking action outside of metamask
*
* @returns {string} A single word label that represents the type of window through which the app is being viewed
*
*/
const getEnvironmentType = (url = window.location.href) => {
if (url.match(/popup.html(?:#.*)*$/)) {
return ENVIRONMENT_TYPE_POPUP
} else if (url.match(/home.html(?:\?.+)*$/) || url.match(/home.html(?:#.*)*$/)) {
return ENVIRONMENT_TYPE_FULLSCREEN
} else {
return ENVIRONMENT_TYPE_NOTIFICATION
}
}
/**
* Checks whether a given balance of ETH, represented as a hex string, is sufficient to pay a value plus a gas fee
*
* @param {object} txParams Contains data about a transaction
* @param {string} txParams.gas The gas for a transaction
* @param {string} txParams.gasPrice The price per gas for the transaction
* @param {string} txParams.value The value of ETH to send
* @param {string} hexBalance A balance of ETH represented as a hex string
* @returns {boolean} Whether the balance is greater than or equal to the value plus the value of gas times gasPrice
*
*/
function sufficientBalance (txParams, hexBalance) {
// validate hexBalance is a hex string
assert.equal(typeof hexBalance, 'string', 'sufficientBalance - hexBalance is not a hex string')
assert.equal(hexBalance.slice(0, 2), '0x', 'sufficientBalance - hexBalance is not a hex string')
const balance = hexToBn(hexBalance)
const value = hexToBn(txParams.value)
const gasLimit = hexToBn(txParams.gas)
const gasPrice = hexToBn(txParams.gasPrice)
const maxCost = value.add(gasLimit.mul(gasPrice))
return balance.gte(maxCost)
}
/**
* Converts a BN object to a hex string with a '0x' prefix
*
* @param {BN} inputBn The BN to convert to a hex string
* @returns {string} A '0x' prefixed hex string
*
*/
function bnToHex (inputBn) {
return ethUtil.addHexPrefix(inputBn.toString(16))
}
/**
* Converts a hex string to a BN object
*
* @param {string} inputHex A number represented as a hex string
* @returns {Object} A BN object
*
*/
function hexToBn (inputHex) {
return new BN(ethUtil.stripHexPrefix(inputHex), 16)
}
/**
* Used to multiply a BN by a fraction
*
* @param {BN} targetBN The number to multiply by a fraction
* @param {number|string} numerator The numerator of the fraction multiplier
* @param {number|string} denominator The denominator of the fraction multiplier
* @returns {BN} The product of the multiplication
*
*/
function BnMultiplyByFraction (targetBN, numerator, denominator) {
const numBN = new BN(numerator)
const denomBN = new BN(denominator)
return targetBN.mul(numBN).div(denomBN)
}
module.exports = {
getStack,
getEnvironmentType,
sufficientBalance,
hexToBn,
bnToHex,
BnMultiplyByFraction,
}
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