1 files changed, 73 insertions, 8 deletions

diff --git a/app/scripts/lib/util.js b/app/scripts/lib/util.js
index 6dee9edf0..431d1e59c 100644
--- a/app/scripts/lib/util.js
+++ b/app/scripts/lib/util.js
@@ -1,20 +1,53 @@
 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')
 
-module.exports = {
-  getStack,
-  sufficientBalance,
-  hexToBn,
-  bnToHex,
-  BnMultiplyByFraction,
-}
-
+/**
+ * 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')
@@ -29,16 +62,48 @@ function sufficientBalance (txParams, hexBalance) {
   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,
+}