Auto-detect tokens #3034 (#4683)

* detect tokens polling

* network store to detect token

* tests for spec

* passtest-lint

* fix lint

* improve tests

* detect tokens through infura

* detect tokens when submit password and new account selected

* keyring unlocked detect and unit tests

* add changelog

2 files changed, 134 insertions, 1 deletions

diff --git a/app/scripts/controllers/detect-tokens.js b/app/scripts/controllers/detect-tokens.js
new file mode 100644
index 000000000..f1810cfa1
--- /dev/null
+++ b/app/scripts/controllers/detect-tokens.js
@@ -0,0 +1,123 @@
+const Web3 = require('web3')
+const contracts = require('eth-contract-metadata')
+const { warn } = require('loglevel')
+const { MAINNET } = require('./network/enums')
+// By default, poll every 3 minutes
+const DEFAULT_INTERVAL = 180 * 1000
+const ERC20_ABI = [{'constant': true, 'inputs': [{'name': '_owner', 'type': 'address'}], 'name': 'balanceOf', 'outputs': [{'name': 'balance', 'type': 'uint256'}], 'payable': false, 'type': 'function'}]
+
+/**
+ * A controller that polls for token exchange
+ * rates based on a user's current token list
+ */
+class DetectTokensController {
+  /**
+   * Creates a DetectTokensController
+   *
+   * @param {Object} [config] - Options to configure controller
+   */
+  constructor ({ interval = DEFAULT_INTERVAL, preferences, network, keyringMemStore } = {}) {
+    this.preferences = preferences
+    this.interval = interval
+    this.network = network
+    this.keyringMemStore = keyringMemStore
+  }
+
+  /**
+   * For each token in eth-contract-metada, find check selectedAddress balance.
+   *
+   */
+  async detectNewTokens () {
+    if (!this.isActive) { return }
+    if (this._network.store.getState().provider.type !== MAINNET) { return }
+    this.web3.setProvider(this._network._provider)
+    for (const contractAddress in contracts) {
+      if (contracts[contractAddress].erc20 && !(this.tokenAddresses.includes(contractAddress.toLowerCase()))) {
+        this.detectTokenBalance(contractAddress)
+      }
+    }
+  }
+
+   /**
+   * Find if selectedAddress has tokens with contract in contractAddress.
+   *
+   * @param {string} contractAddress Hex address of the token contract to explore.
+   * @returns {boolean} If balance is detected, token is added.
+   *
+   */
+  async detectTokenBalance (contractAddress) {
+    const ethContract = this.web3.eth.contract(ERC20_ABI).at(contractAddress)
+    ethContract.balanceOf(this.selectedAddress, (error, result) => {
+      if (!error) {
+        if (!result.isZero()) {
+          this._preferences.addToken(contractAddress, contracts[contractAddress].symbol, contracts[contractAddress].decimals)
+        }
+      } else {
+        warn(`MetaMask - DetectTokensController balance fetch failed for ${contractAddress}.`, error)
+      }
+    })
+  }
+
+  /**
+   * Restart token detection polling period and call detectNewTokens
+   * in case of address change or user session initialization.
+   *
+   */
+  restartTokenDetection () {
+    if (this.isActive && this.selectedAddress) {
+      this.detectNewTokens()
+      this.interval = DEFAULT_INTERVAL
+    }
+  }
+
+  /**
+   * @type {Number}
+   */
+  set interval (interval) {
+    this._handle && clearInterval(this._handle)
+    if (!interval) { return }
+    this._handle = setInterval(() => { this.detectNewTokens() }, interval)
+  }
+
+  /**
+   * In setter when selectedAddress is changed, detectNewTokens and restart polling
+   * @type {Object}
+   */
+  set preferences (preferences) {
+    if (!preferences) { return }
+    this._preferences = preferences
+    preferences.store.subscribe(({ tokens }) => { this.tokenAddresses = tokens.map((obj) => { return obj.address }) })
+    preferences.store.subscribe(({ selectedAddress }) => {
+      if (this.selectedAddress !== selectedAddress) {
+        this.selectedAddress = selectedAddress
+        this.restartTokenDetection()
+      }
+    })
+  }
+
+  /**
+   * @type {Object}
+   */
+  set network (network) {
+    if (!network) { return }
+    this._network = network
+    this.web3 = new Web3(network._provider)
+  }
+
+  /**
+   * In setter when isUnlocked is updated to true, detectNewTokens and restart polling
+   * @type {Object}
+   */
+  set keyringMemStore (keyringMemStore) {
+    if (!keyringMemStore) { return }
+    this._keyringMemStore = keyringMemStore
+    this._keyringMemStore.subscribe(({ isUnlocked }) => {
+      if (this.isUnlocked !== isUnlocked) {
+        if (isUnlocked) { this.restartTokenDetection() }
+        this.isUnlocked = isUnlocked
+      }
+    })
+  }
+}
+
+module.exports = DetectTokensController
diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index dc5c24b1b..6f5908414 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -35,6 +35,7 @@ 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 DetectTokensController = require('./controllers/detect-tokens')
 const ConfigManager = require('./lib/config-manager')
 const nodeify = require('./lib/nodeify')
 const accountImporter = require('./account-import-strategies')
@@ -147,6 +148,13 @@ module.exports = class MetamaskController extends EventEmitter {
       this.accountTracker.syncWithAddresses(addresses)
     })
 
+    // detect tokens controller
+    this.detectTokensController = new DetectTokensController({
+      preferences: this.preferencesController,
+      network: this.networkController,
+      keyringMemStore: this.keyringController.memStore,
+    })
+
     // address book controller
     this.addressBookController = new AddressBookController({
       initState: initState.AddressBookController,
@@ -1420,11 +1428,13 @@ module.exports = class MetamaskController extends EventEmitter {
   }
 
   /**
-   * A method for activating the retrieval of price data, which should only be fetched when the UI is visible.
+   * A method for activating the retrieval of price data and auto detect tokens, 
+   * which should only be fetched when the UI is visible.
    * @private
    * @param {boolean} active - True if price data should be getting fetched.
    */
   set isClientOpenAndUnlocked (active) {
     this.tokenRatesController.isActive = active
+    this.detectTokensController.isActive = active
   }
 }