1 files changed, 312 insertions, 0 deletions
diff --git a/ui/app/components/send/send.utils.js b/ui/app/components/send/send.utils.js
new file mode 100644
index 000000000..aa255c3d4
--- /dev/null
+++ b/ui/app/components/send/send.utils.js
@@ -0,0 +1,312 @@
+const {
+  addCurrencies,
+  conversionUtil,
+  conversionGTE,
+  multiplyCurrencies,
+  conversionGreaterThan,
+  conversionLessThan,
+} = require('../../conversion-util')
+const {
+  calcTokenAmount,
+} = require('../../token-util')
+const {
+  BASE_TOKEN_GAS_COST,
+  INSUFFICIENT_FUNDS_ERROR,
+  INSUFFICIENT_TOKENS_ERROR,
+  NEGATIVE_ETH_ERROR,
+  ONE_GWEI_IN_WEI_HEX,
+  SIMPLE_GAS_COST,
+  TOKEN_TRANSFER_FUNCTION_SIGNATURE,
+} = require('./send.constants')
+const abi = require('ethereumjs-abi')
+const ethUtil = require('ethereumjs-util')
+
+module.exports = {
+  addGasBuffer,
+  calcGasTotal,
+  calcTokenBalance,
+  doesAmountErrorRequireUpdate,
+  estimateGas,
+  estimateGasPriceFromRecentBlocks,
+  generateTokenTransferData,
+  getAmountErrorObject,
+  getGasFeeErrorObject,
+  getToAddressForGasUpdate,
+  isBalanceSufficient,
+  isTokenBalanceSufficient,
+  removeLeadingZeroes,
+}
+
+function calcGasTotal (gasLimit = '0', gasPrice = '0') {
+  return multiplyCurrencies(gasLimit, gasPrice, {
+    toNumericBase: 'hex',
+    multiplicandBase: 16,
+    multiplierBase: 16,
+  })
+}
+
+function isBalanceSufficient ({
+  amount = '0x0',
+  amountConversionRate = 1,
+  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: Number(amountConversionRate) || conversionRate,
+      fromCurrency: primaryCurrency,
+    },
+  )
+
+  return balanceIsSufficient
+}
+
+function isTokenBalanceSufficient ({
+  amount = '0x0',
+  tokenBalance,
+  decimals,
+}) {
+  const amountInDec = conversionUtil(amount, {
+    fromNumericBase: 'hex',
+  })
+
+  const tokenBalanceIsSufficient = conversionGTE(
+    {
+      value: tokenBalance,
+      fromNumericBase: 'dec',
+    },
+    {
+      value: calcTokenAmount(amountInDec, decimals),
+      fromNumericBase: 'dec',
+    },
+  )
+
+  return tokenBalanceIsSufficient
+}
+
+function getAmountErrorObject ({
+  amount,
+  amountConversionRate,
+  balance,
+  conversionRate,
+  gasTotal,
+  primaryCurrency,
+  selectedToken,
+  tokenBalance,
+}) {
+  let insufficientFunds = false
+  if (gasTotal && conversionRate && !selectedToken) {
+    insufficientFunds = !isBalanceSufficient({
+      amount,
+      amountConversionRate,
+      balance,
+      conversionRate,
+      gasTotal,
+      primaryCurrency,
+    })
+  }
+
+  let inSufficientTokens = false
+  if (selectedToken && tokenBalance !== null) {
+    const { decimals } = selectedToken
+    inSufficientTokens = !isTokenBalanceSufficient({
+      tokenBalance,
+      amount,
+      decimals,
+    })
+  }
+
+  const amountLessThanZero = conversionGreaterThan(
+    { value: 0, fromNumericBase: 'dec' },
+    { value: amount, fromNumericBase: 'hex' },
+  )
+
+  let amountError = null
+
+  if (insufficientFunds) {
+    amountError = INSUFFICIENT_FUNDS_ERROR
+  } else if (inSufficientTokens) {
+    amountError = INSUFFICIENT_TOKENS_ERROR
+  } else if (amountLessThanZero) {
+    amountError = NEGATIVE_ETH_ERROR
+  }
+
+  return { amount: amountError }
+}
+
+function getGasFeeErrorObject ({
+  amount,
+  amountConversionRate,
+  balance,
+  conversionRate,
+  gasTotal,
+  primaryCurrency,
+}) {
+  let gasFeeError = null
+
+  if (gasTotal && conversionRate) {
+    const insufficientFunds = !isBalanceSufficient({
+      amount: '0x0',
+      amountConversionRate,
+      balance,
+      conversionRate,
+      gasTotal,
+      primaryCurrency,
+    })
+
+    if (insufficientFunds) {
+      gasFeeError = INSUFFICIENT_FUNDS_ERROR
+    }
+  }
+
+  return { gasFee: gasFeeError }
+}
+
+function calcTokenBalance ({ selectedToken, usersToken }) {
+  const { decimals } = selectedToken || {}
+  return calcTokenAmount(usersToken.balance.toString(), decimals) + ''
+}
+
+function doesAmountErrorRequireUpdate ({
+  balance,
+  gasTotal,
+  prevBalance,
+  prevGasTotal,
+  prevTokenBalance,
+  selectedToken,
+  tokenBalance,
+}) {
+  const balanceHasChanged = balance !== prevBalance
+  const gasTotalHasChange = gasTotal !== prevGasTotal
+  const tokenBalanceHasChanged = selectedToken && tokenBalance !== prevTokenBalance
+  const amountErrorRequiresUpdate = balanceHasChanged || gasTotalHasChange || tokenBalanceHasChanged
+
+  return amountErrorRequiresUpdate
+}
+
+async function estimateGas ({ selectedAddress, selectedToken, blockGasLimit, to, value, gasPrice, estimateGasMethod }) {
+  const paramsForGasEstimate = { from: selectedAddress, value, gasPrice }
+
+  if (selectedToken) {
+    paramsForGasEstimate.value = '0x0'
+    paramsForGasEstimate.data = generateTokenTransferData({ toAddress: to, amount: value, selectedToken })
+  }
+
+  // if recipient has no code, gas is 21k max:
+  if (!selectedToken) {
+    const code = Boolean(to) && await global.eth.getCode(to)
+    if (!code || code === '0x') {
+      return SIMPLE_GAS_COST
+    }
+  } else if (selectedToken && !to) {
+    return BASE_TOKEN_GAS_COST
+  }
+
+  paramsForGasEstimate.to = selectedToken ? selectedToken.address : to
+
+  // if not, fall back to block gasLimit
+  paramsForGasEstimate.gas = ethUtil.addHexPrefix(multiplyCurrencies(blockGasLimit, 0.95, {
+    multiplicandBase: 16,
+    multiplierBase: 10,
+    roundDown: '0',
+    toNumericBase: 'hex',
+  }))
+  // run tx
+  return new Promise((resolve, reject) => {
+    return estimateGasMethod(paramsForGasEstimate, (err, estimatedGas) => {
+      if (err) {
+        const simulationFailed = (
+          err.message.includes('Transaction execution error.') ||
+          err.message.includes('gas required exceeds allowance or always failing transaction')
+        )
+        if (simulationFailed) {
+          const estimateWithBuffer = addGasBuffer(paramsForGasEstimate.gas, blockGasLimit, 1.5)
+          return resolve(ethUtil.addHexPrefix(estimateWithBuffer))
+        } else {
+          return reject(err)
+        }
+      }
+      const estimateWithBuffer = addGasBuffer(estimatedGas.toString(16), blockGasLimit, 1.5)
+      return resolve(ethUtil.addHexPrefix(estimateWithBuffer))
+    })
+  })
+}
+
+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', selectedToken }) {
+  if (!selectedToken) return
+  return TOKEN_TRANSFER_FUNCTION_SIGNATURE + Array.prototype.map.call(
+    abi.rawEncode(['address', 'uint256'], [toAddress, ethUtil.addHexPrefix(amount)]),
+    x => ('00' + x.toString(16)).slice(-2)
+  ).join('')
+}
+
+function estimateGasPriceFromRecentBlocks (recentBlocks) {
+  // Return 1 gwei if no blocks have been observed:
+  if (!recentBlocks || recentBlocks.length === 0) {
+    return ONE_GWEI_IN_WEI_HEX
+  }
+
+  const lowestPrices = recentBlocks.map((block) => {
+    if (!block.gasPrices || block.gasPrices.length < 1) {
+      return ONE_GWEI_IN_WEI_HEX
+    }
+    return block.gasPrices.reduce((currentLowest, next) => {
+      return parseInt(next, 16) < parseInt(currentLowest, 16) ? next : currentLowest
+    })
+  })
+  .sort((a, b) => parseInt(a, 16) > parseInt(b, 16) ? 1 : -1)
+
+  return lowestPrices[Math.floor(lowestPrices.length / 2)]
+}
+
+function getToAddressForGasUpdate (...addresses) {
+  return [...addresses, ''].find(str => str !== undefined && str !== null).toLowerCase()
+}
+
+function removeLeadingZeroes (str) {
+  return str.replace(/^0*(?=\d)/, '')
+}