petnunia.js

if (typeof web3 !== 'undefined' && typeof Web3 !== 'undefined') {
  web3 = new Web3(web3.currentProvider);
} else if (typeof Web3 !== 'undefined') {
  console.log('No web3? You should consider trying MetaMask!')
  web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545'));
}

myApp.config(function ($provide) {
  $provide.provider('ethClinet', function () {
    this.$get = function () {
      return web3;
    };
  });
});

myApp.service('Petunia', ['ethClinet', '$q', function (ethClinet, $q) {
  //here we build object that represents petunia smart contract
  const petunia = ethClinet.eth.contract(contractABI).at(contractAddress);

  var account = null;
  //here we fetch accounts that are available e.g. were added to Metamask
  $q((resolve, reject) => ethClinet.eth.getAccounts(function (e, r) {
    if (e) {
      reject(e);
    } else {
      account = r[0];
    }
  }));
  ///...
});