1 files changed, 105 insertions, 0 deletions
diff --git a/ui/app/helpers/with-token-tracker.js b/ui/app/helpers/with-token-tracker.js
new file mode 100644
index 000000000..e24517c18
--- /dev/null
+++ b/ui/app/helpers/with-token-tracker.js
@@ -0,0 +1,105 @@
+import React, { Component } from 'react'
+import PropTypes from 'prop-types'
+import TokenTracker from 'eth-token-tracker'
+
+const withTokenTracker = WrappedComponent => {
+  return class TokenTrackerWrappedComponent extends Component {
+    static propTypes = {
+      userAddress: PropTypes.string.isRequired,
+      token: PropTypes.object.isRequired,
+    }
+
+    constructor (props) {
+      super(props)
+
+      this.state = {
+        string: '',
+        symbol: '',
+        error: null,
+      }
+
+      this.tracker = null
+      this.updateBalance = this.updateBalance.bind(this)
+      this.setError = this.setError.bind(this)
+    }
+
+    componentDidMount () {
+      this.createFreshTokenTracker()
+    }
+
+    componentDidUpdate (prevProps) {
+      const { userAddress: newAddress, token: { address: newTokenAddress } } = this.props
+      const { userAddress: oldAddress, token: { address: oldTokenAddress } } = prevProps
+
+      if ((oldAddress === newAddress) && (oldTokenAddress === newTokenAddress)) {
+        return
+      }
+
+      if ((!oldAddress || !newAddress) && (!oldTokenAddress || !newTokenAddress)) {
+        return
+      }
+
+      this.createFreshTokenTracker()
+    }
+
+    componentWillUnmount () {
+      this.removeListeners()
+    }
+
+    createFreshTokenTracker () {
+      this.removeListeners()
+
+      if (!global.ethereumProvider) {
+        return
+      }
+
+      const { userAddress, token } = this.props
+
+      this.tracker = new TokenTracker({
+        userAddress,
+        provider: global.ethereumProvider,
+        tokens: [token],
+        pollingInterval: 8000,
+      })
+
+      this.tracker.on('update', this.updateBalance)
+      this.tracker.on('error', this.setError)
+
+      this.tracker.updateBalances()
+        .then(() => this.updateBalance(this.tracker.serialize()))
+        .catch(error => this.setState({ error: error.message }))
+    }
+
+    setError (error) {
+      this.setState({ error })
+    }
+
+    updateBalance (tokens = []) {
+      const [{ string, symbol }] = tokens
+      this.setState({ string, symbol, error: null })
+    }
+
+    removeListeners () {
+      if (this.tracker) {
+        this.tracker.stop()
+        this.tracker.removeListener('update', this.updateBalance)
+        this.tracker.removeListener('error', this.setError)
+      }
+    }
+
+    render () {
+      const { string, symbol, error } = this.state
+
+      return (
+        <WrappedComponent
+          { ...this.props }
+          string={string}
+          symbol={symbol}
+          error={error}
+        />
+      )
+    }
+  }
+}
+
+module.exports = withTokenTracker