snt-voting/app/components/flow/ExternalWallet.js

import React, {Component} from 'react';
import { withRouter } from 'react-router-dom'
import SNT from  'Embark/contracts/SNT';
import PollManager from  'Embark/contracts/PollManager';

class ExternalWallet extends Component {
    
    componentDidUpdate(prevProps){
        if (this.props.polls !== prevProps.polls && this.props.polls && this.props.polls.length) {
            this.connectWallet();
        }
    }

    componentDidMount(){
        this.connectWallet();
    }

    connectWallet = async () => {
        const {history, polls, updateBalances, idPoll} = this.props;
        if(!polls || !polls.length) return;


        let cont = true;
        if (window.ethereum) {
          try {
              await ethereum.enable();
              web3.setProvider(ethereum);
              const accounts = await web3.eth.getAccounts();
              web3.eth.defaultAccount = accounts[0];
          } catch (error) {
            cont = false;
          }
        }
        
        if(cont){
            // TODO: extract this code to utils. It's repeated in ConnectYourWallt, ExternalWallet and HowVotingWorks
            const poll = polls[polls.length - 1];
            const tknVotes = await PollManager.methods.getVote(idPoll, web3.eth.defaultAccount).call();  
            const votes = tknVotes.map(x => Math.sqrt(parseInt(web3.utils.fromWei(x, "ether"))));            
            const tokenBalance = await SNT.methods.balanceOfAt(web3.eth.defaultAccount, poll._startBlock).call();
            const ethBalance = await web3.eth.getBalance(web3.eth.defaultAccount);
            updateBalances(idPoll, tokenBalance, ethBalance, votes);
            

            history.push('/votingCredits/' + idPoll);
        }
    };

    render(){
        return null;
    }
}

export default withRouter(ExternalWallet);