Maintain token prices using a background service

7 files changed, 117 insertions, 81 deletions

diff --git a/app/scripts/controllers/token-rates.js b/app/scripts/controllers/token-rates.js
new file mode 100644
index 000000000..85a8ca24e
--- /dev/null
+++ b/app/scripts/controllers/token-rates.js
@@ -0,0 +1,76 @@
+const ObservableStore = require('obs-store')
+
+// By default, poll every 3 minutes
+const DEFAULT_INTERVAL = 180 * 1000
+
+/**
+ * A controller that polls for token exchange
+ * rates based on a user's current token list
+ */
+class TokenRatesController {
+  /**
+   * Creates a TokenRatesController
+   *
+   * @param {Object} [config] - Options to configure controller
+   */
+  constructor ({ interval = DEFAULT_INTERVAL, preferences } = {}) {
+    this.store = new ObservableStore()
+    this.preferences = preferences
+    this.interval = interval
+  }
+
+  /**
+   * Updates exchange rates for all tokens
+   */
+  async updateExchangeRates () {
+    const contractExchangeRates = {}
+    for (const i in this._tokens) {
+      const address = this._tokens[i].address
+      contractExchangeRates[address] = await this.fetchExchangeRate(address)
+    }
+    this.store.putState({ contractExchangeRates })
+  }
+
+  /**
+   * Fetches a token exchange rate by address
+   *
+   * @param {String} address - Token contract address
+   */
+  async fetchExchangeRate (address) {
+    try {
+      const response = await fetch(`https://exchanges.balanc3.net/prices?from=${address}&to=ETH&autoConversion=false&summaryOnly=true`)
+      const json = await response.json()
+      return json && json.length ? json[0].averagePrice : 0
+    } catch (error) { }
+  }
+
+  /**
+   * @type {Number} - Interval used to poll for exchange rates
+   */
+  set interval (interval) {
+    this._handle && clearInterval(this._handle)
+    if (!interval) { return }
+    this._handle = setInterval(() => { this.updateExchangeRates() }, interval)
+  }
+
+  /**
+   * @type {Object} - Preferences controller instance
+   */
+  set preferences (preferences) {
+    this._preferences && this._preferences.unsubscribe()
+    if (!preferences) { return }
+    this._preferences = preferences
+    this.tokens = preferences.getState().tokens
+    preferences.subscribe(({ tokens = [] }) => { this.tokens = tokens })
+  }
+
+  /**
+   * @type {Array} - Array of token objects with contract addresses
+   */
+  set tokens (tokens) {
+    this._tokens = tokens
+    this.updateExchangeRates()
+  }
+}
+
+module.exports = TokenRatesController
diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index fa7890c50..750a97b86 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -34,6 +34,7 @@ const PersonalMessageManager = require('./lib/personal-message-manager')
 const TypedMessageManager = require('./lib/typed-message-manager')
 const TransactionController = require('./controllers/transactions')
 const BalancesController = require('./controllers/computed-balances')
+const TokenRatesController = require('./controllers/token-rates')
 const ConfigManager = require('./lib/config-manager')
 const nodeify = require('./lib/nodeify')
 const accountImporter = require('./account-import-strategies')
@@ -104,6 +105,11 @@ module.exports = class MetamaskController extends EventEmitter {
     this.provider = this.initializeProvider()
     this.blockTracker = this.provider._blockTracker
 
+    // token exchange rate tracker
+    this.tokenRatesController = new TokenRatesController({
+      preferences: this.preferencesController.store,
+    })
+
     this.recentBlocksController = new RecentBlocksController({
       blockTracker: this.blockTracker,
       provider: this.provider,
@@ -201,6 +207,7 @@ module.exports = class MetamaskController extends EventEmitter {
       AccountTracker: this.accountTracker.store,
       TxController: this.txController.memStore,
       BalancesController: this.balancesController.store,
+      TokenRatesController: this.tokenRatesController.store,
       MessageManager: this.messageManager.memStore,
       PersonalMessageManager: this.personalMessageManager.memStore,
       TypesMessageManager: this.typedMessageManager.memStore,
diff --git a/test/unit/token-rates-controller.js b/test/unit/token-rates-controller.js
new file mode 100644
index 000000000..55bfe7823
--- /dev/null
+++ b/test/unit/token-rates-controller.js
@@ -0,0 +1,28 @@
+const assert = require('assert')
+const sinon = require('sinon')
+const TokenRatesController = require('../../app/scripts/controllers/token-rates')
+const ObservableStore = require('obs-store')
+
+describe('TokenRatesController', () => {
+  it('should listen for preferences store updates', () => {
+    const preferences = new ObservableStore({ tokens: [] })
+    const controller = new TokenRatesController({ preferences })
+    preferences.putState({ tokens: ['foo'] })
+    assert.deepEqual(controller._tokens, ['foo'])
+  })
+
+  it('should poll on correct interval', async () => {
+    const stub = sinon.stub(global, 'setInterval')
+    new TokenRatesController({ interval: 1337 }) // eslint-disable-line no-new
+    assert.strictEqual(stub.getCall(0).args[1], 1337)
+    stub.restore()
+  })
+
+  it('should fetch each token rate based on address', async () => {
+    const controller = new TokenRatesController()
+    controller.fetchExchangeRate = address => address
+    controller.tokens = [{ address: 'foo' }, { address: 'bar' }]
+    await controller.updateExchangeRates()
+    assert.deepEqual(controller.store.getState().contractExchangeRates, { foo: 'foo', bar: 'bar' })
+  })
+})
diff --git a/ui/app/actions.js b/ui/app/actions.js
index 6453a2bc2..46f34e149 100644
--- a/ui/app/actions.js
+++ b/ui/app/actions.js
@@ -220,10 +220,6 @@ var actions = {
   coinBaseSubview: coinBaseSubview,
   SHAPESHIFT_SUBVIEW: 'SHAPESHIFT_SUBVIEW',
   shapeShiftSubview: shapeShiftSubview,
-  UPDATE_CONTRACT_EXCHANGE_RATES: 'UPDATE_CONTRACT_EXCHANGE_RATES',
-  UPDATE_CONTRACT_EXCHANGE_RATE: 'UPDATE_CONTRACT_EXCHANGE_RATE',
-  updateContractExchangeRates,
-  updateContractExchangeRate,
   PAIR_UPDATE: 'PAIR_UPDATE',
   pairUpdate: pairUpdate,
   coinShiftRquest: coinShiftRquest,
@@ -1082,12 +1078,9 @@ function unlockMetamask (account) {
 }
 
 function updateMetamaskState (newState) {
-  return async dispatch => {
-    await dispatch({
-      type: actions.UPDATE_METAMASK_STATE,
-      value: newState,
-    })
-    dispatch(updateContractExchangeRates())
+  return {
+    type: actions.UPDATE_METAMASK_STATE,
+    value: newState,
   }
 }
 
@@ -1300,12 +1293,9 @@ function addTokens (tokens) {
 }
 
 function updateTokens (newTokens) {
-  return async dispatch => {
-    await dispatch({
-      type: actions.UPDATE_TOKENS,
-      newTokens,
-    })
-    dispatch(updateContractExchangeRates())
+  return {
+    type: actions.UPDATE_TOKENS,
+    newTokens,
   }
 }
 
@@ -1759,42 +1749,6 @@ function shapeShiftRequest (query, options, cb) {
   }
 }
 
-async function fetchContractRate (address) {
-  try {
-    const response = await fetch(`https://exchanges.balanc3.net/prices?from=${address}&to=ETH&autoConversion=false&summaryOnly=true`)
-    const json = await response.json()
-    const rate = json && json.length ? json[0].averagePrice : 0
-    return { address, rate }
-  } catch (error) { }
-}
-
-function updateContractExchangeRates () {
-  return async (dispatch, getState) => {
-    const { metamask: { tokens = [] } } = getState()
-    const newExchangeRates = {}
-
-    for (const i in tokens) {
-      const address = tokens[i].address
-      newExchangeRates[address] = (await fetchContractRate(address)).rate
-    }
-
-    dispatch({
-      type: actions.UPDATE_CONTRACT_EXCHANGE_RATES,
-      payload: { newExchangeRates },
-    })
-  }
-}
-
-function updateContractExchangeRate (address) {
-  return async dispatch => {
-    const { address, rate } = await fetchContractRate(address)
-    dispatch({
-      type: actions.UPDATE_CONTRACT_EXCHANGE_RATE,
-      payload: { address, rate },
-    })
-  }
-}
-
 function setFeatureFlag (feature, activated, notificationType) {
   return (dispatch) => {
     dispatch(actions.showLoadingIndication())
diff --git a/ui/app/components/send/send-v2-container.js b/ui/app/components/send/send-v2-container.js
index 75f16b382..adfc91240 100644
--- a/ui/app/components/send/send-v2-container.js
+++ b/ui/app/components/send/send-v2-container.js
@@ -66,7 +66,6 @@ function mapDispatchToProps (dispatch) {
     showCustomizeGasModal: () => dispatch(actions.showModal({ name: 'CUSTOMIZE_GAS' })),
     estimateGas: params => dispatch(actions.estimateGas(params)),
     getGasPrice: () => dispatch(actions.getGasPrice()),
-    updateContractExchangeRate: address => dispatch(actions.updateContractExchangeRate(address)),
     signTokenTx: (tokenAddress, toAddress, amount, txData) => (
       dispatch(actions.signTokenTx(tokenAddress, toAddress, amount, txData))
     ),
diff --git a/ui/app/reducers/metamask.js b/ui/app/reducers/metamask.js
index d6b6de3b0..1ed049be2 100644
--- a/ui/app/reducers/metamask.js
+++ b/ui/app/reducers/metamask.js
@@ -177,23 +177,6 @@ function reduceMetamask (state, action) {
         conversionDate: action.value.conversionDate,
       })
 
-    case actions.UPDATE_CONTRACT_EXCHANGE_RATES:
-      const { payload: { newExchangeRates } } = action
-      return {
-        ...metamaskState,
-        contractExchangeRates: newExchangeRates,
-      }
-
-    case actions.UPDATE_CONTRACT_EXCHANGE_RATE:
-      const { payload: { address, rate } } = action
-      return {
-        ...metamaskState,
-        contractExchangeRates: {
-          ...metamaskState.contractExchangeRates,
-          [address]: rate,
-        },
-      }
-
     case actions.UPDATE_TOKENS:
       return extend(metamaskState, {
         tokens: action.newTokens,
diff --git a/ui/app/send-v2.js b/ui/app/send-v2.js
index 12cf55f62..30d3d3152 100644
--- a/ui/app/send-v2.js
+++ b/ui/app/send-v2.js
@@ -88,17 +88,6 @@ SendTransactionScreen.prototype.updateSendTokenBalance = function (usersToken) {
 }
 
 SendTransactionScreen.prototype.componentWillMount = function () {
-  const {
-    updateContractExchangeRate,
-    selectedToken = {},
-  } = this.props
-
-  const { address } = selectedToken || {}
-
-  if (address) {
-    updateContractExchangeRate(address)
-  }
-
   this.updateGas()
 }