From 7924dbc0c99730c500169c1a31cccd64b75cbce0 Mon Sep 17 00:00:00 2001
From: Alexander Tseung <alextsg@gmail.com>
Date: Wed, 22 Aug 2018 16:54:18 -0700
Subject: [PATCH] Use eth-contract-metadata data if the token symbol or
 decimals fail on retrieval

---
 ui/app/token-util.js | 116 ++++++++++++++++++++++++++++++++-----------
 1 file changed, 87 insertions(+), 29 deletions(-)

diff --git a/ui/app/token-util.js b/ui/app/token-util.js
index 8798ed266..3d61ad1ca 100644
--- a/ui/app/token-util.js
+++ b/ui/app/token-util.js
@@ -1,55 +1,113 @@
 const log = require('loglevel')
 const util = require('./util')
 const BigNumber = require('bignumber.js')
+import contractMap from 'eth-contract-metadata'
 
-function tokenInfoGetter () {
-  const tokens = {}
+const casedContractMap = Object.keys(contractMap).reduce((acc, base) => {
+  return {
+    ...acc,
+    [base.toLowerCase()]: contractMap[base],
+  }
+}, {})
 
-  return async (address) => {
-    if (tokens[address]) {
-      return tokens[address]
+const DEFAULT_SYMBOL = ''
+const DEFAULT_DECIMALS = '0'
+
+async function getSymbolFromContract (tokenAddress) {
+  const token = util.getContractAtAddress(tokenAddress)
+
+  try {
+    const result = await token.symbol()
+    return result[0]
+  } catch (error) {
+    log.warn(`symbol() call for token at address ${tokenAddress} resulted in error:`, error)
+  }
+}
+
+async function getDecimalsFromContract (tokenAddress) {
+  const token = util.getContractAtAddress(tokenAddress)
+
+  try {
+    const result = await token.decimals()
+    const decimalsBN = result[0]
+    return decimalsBN && decimalsBN.toString()
+  } catch (error) {
+    log.warn(`decimals() call for token at address ${tokenAddress} resulted in error:`, error)
+  }
+}
+
+function getContractMetadata (tokenAddress) {
+  return tokenAddress && casedContractMap[tokenAddress.toLowerCase()]
+}
+
+async function getSymbol (tokenAddress) {
+  let symbol = await getSymbolFromContract(tokenAddress)
+
+  if (!symbol) {
+    const contractMetadataInfo = getContractMetadata(tokenAddress)
+
+    if (contractMetadataInfo) {
+      symbol = contractMetadataInfo.symbol
     }
+  }
 
-    tokens[address] = await getSymbolAndDecimals(address)
+  return symbol
+}
 
-    return tokens[address]
+async function getDecimals (tokenAddress) {
+  let decimals = await getDecimalsFromContract(tokenAddress)
+
+  if (!decimals || decimals === '0') {
+    const contractMetadataInfo = getContractMetadata(tokenAddress)
+
+    if (contractMetadataInfo) {
+      decimals = contractMetadataInfo.decimals
+    }
   }
+
+  return decimals
 }
 
-async function getSymbolAndDecimals (tokenAddress, existingTokens = []) {
+export async function getSymbolAndDecimals (tokenAddress, existingTokens = []) {
   const existingToken = existingTokens.find(({ address }) => tokenAddress === address)
+
   if (existingToken) {
-    return existingToken
+    return {
+      symbol: existingToken.symbol,
+      decimals: existingToken.decimals,
+    }
   }
 
-  let result = []
+  let symbol, decimals
+
   try {
-    const token = util.getContractAtAddress(tokenAddress)
+    symbol = await getSymbol(tokenAddress)
+    decimals = await getDecimals(tokenAddress)
+  } catch (error) {
+    log.warn(`symbol() and decimal() calls for token at address ${tokenAddress} resulted in error:`, error)
+  }
 
-    result = await Promise.all([
-      token.symbol(),
-      token.decimals(),
-    ])
-  } catch (err) {
-    log.warn(`symbol() and decimal() calls for token at address ${tokenAddress} resulted in error:`, err)
+  return {
+    symbol: symbol || DEFAULT_SYMBOL,
+    decimals: decimals || DEFAULT_DECIMALS,
   }
+}
+
+export function tokenInfoGetter () {
+  const tokens = {}
 
-  const [ symbol = [], decimals = [] ] = result
+  return async (address) => {
+    if (tokens[address]) {
+      return tokens[address]
+    }
 
-  return {
-    symbol: symbol[0] || null,
-    decimals: decimals[0] && decimals[0].toString() || null,
+    tokens[address] = await getSymbolAndDecimals(address)
+
+    return tokens[address]
   }
 }
 
-function calcTokenAmount (value, decimals) {
+export function calcTokenAmount (value, decimals) {
   const multiplier = Math.pow(10, Number(decimals || 0))
   return new BigNumber(String(value)).div(multiplier).toNumber()
 }
-
-
-module.exports = {
-  tokenInfoGetter,
-  calcTokenAmount,
-  getSymbolAndDecimals,
-}