1 files changed, 113 insertions, 0 deletions
diff --git a/ui/app/components/token-balance.js b/ui/app/components/token-balance.js
new file mode 100644
index 000000000..2f71c0687
--- /dev/null
+++ b/ui/app/components/token-balance.js
@@ -0,0 +1,113 @@
+const Component = require('react').Component
+const h = require('react-hyperscript')
+const inherits = require('util').inherits
+const TokenTracker = require('eth-token-tracker')
+const connect = require('react-redux').connect
+const selectors = require('../selectors')
+
+function mapStateToProps (state) {
+  return {
+    userAddress: selectors.getSelectedAddress(state),
+  }
+}
+
+module.exports = connect(mapStateToProps)(TokenBalance)
+
+
+inherits(TokenBalance, Component)
+function TokenBalance () {
+  this.state = {
+    string: '',
+    symbol: '',
+    isLoading: true,
+    error: null,
+  }
+  Component.call(this)
+}
+
+TokenBalance.prototype.render = function () {
+  const state = this.state
+  const { symbol, string, isLoading } = state
+  const { balanceOnly } = this.props
+
+  return isLoading
+    ? h('span', '')
+    : h('span.token-balance', [
+      h('span.token-balance__amount', string),
+      !balanceOnly && h('span.token-balance__symbol', symbol),
+    ])
+}
+
+TokenBalance.prototype.componentDidMount = function () {
+  this.createFreshTokenTracker()
+}
+
+TokenBalance.prototype.createFreshTokenTracker = function () {
+  if (this.tracker) {
+    // Clean up old trackers when refreshing:
+    this.tracker.stop()
+    this.tracker.removeListener('update', this.balanceUpdater)
+    this.tracker.removeListener('error', this.showError)
+  }
+
+  if (!global.ethereumProvider) return
+  const { userAddress, token } = this.props
+
+  this.tracker = new TokenTracker({
+    userAddress,
+    provider: global.ethereumProvider,
+    tokens: [token],
+    pollingInterval: 8000,
+  })
+
+
+  // Set up listener instances for cleaning up
+  this.balanceUpdater = this.updateBalance.bind(this)
+  this.showError = error => {
+    this.setState({ error, isLoading: false })
+  }
+  this.tracker.on('update', this.balanceUpdater)
+  this.tracker.on('error', this.showError)
+
+  this.tracker.updateBalances()
+    .then(() => {
+      this.updateBalance(this.tracker.serialize())
+    })
+    .catch((reason) => {
+      log.error(`Problem updating balances`, reason)
+      this.setState({ isLoading: false })
+    })
+}
+
+TokenBalance.prototype.componentDidUpdate = function (nextProps) {
+  const {
+    userAddress: oldAddress,
+    token: { address: oldTokenAddress },
+  } = this.props
+  const {
+    userAddress: newAddress,
+    token: { address: newTokenAddress },
+  } = nextProps
+
+  if ((!oldAddress || !newAddress) && (!oldTokenAddress || !newTokenAddress)) return
+  if ((oldAddress === newAddress) && (oldTokenAddress === newTokenAddress)) return
+
+  this.setState({ isLoading: true })
+  this.createFreshTokenTracker()
+}
+
+TokenBalance.prototype.updateBalance = function (tokens = []) {
+  const [{ string, symbol }] = tokens
+
+  this.setState({
+    string,
+    symbol,
+    isLoading: false,
+  })
+}
+
+TokenBalance.prototype.componentWillUnmount = function () {
+  if (!this.tracker) return
+  this.tracker.stop()
+}
+