App navigation with drawer in react-navigation for login stacking

AppNavigation.js

import React from 'react'
import { Text, Animated, Easing } from 'react-native'
import { StackNavigator, DrawerNavigator } from 'react-navigation'
import LoginScreen from '../Containers/LoginScreen'
import SignupScreen from '../Containers/SignupScreen'
import ForgottenPasswordScreen from '../Containers/ForgottenPasswordScreen'
import Screen1 from '../Containers/Screen1'
import Screen2 from '../Containers/Screen2'
import Screen3 from '../Containers/Screen3'

// https://github.com/react-community/react-navigation/issues/1254
const noTransitionConfig = () => ({
  transitionSpec: {
    duration: 0,
    timing: Animated.timing,
    easing: Easing.step0
  }
})

// drawer stack
const DrawerStack = DrawerNavigator({
  screen1: { screen: Screen1 },
  screen2: { screen: Screen2 },
  screen3: { screen: Screen3 },
}, {
  gesturesEnabled: false
})

const DrawerNavigation = StackNavigator({
  DrawerStack: { screen: DrawerStack }
}, {
  headerMode: 'float',
  navigationOptions: ({navigation}) => ({
    headerStyle: {backgroundColor: 'green'},
    title: 'Logged In to your app!',
    gesturesEnabled: false,
    headerLeft: <Text onPress={() => {
      // Coming soon: navigation.navigate('DrawerToggle')
      // https://github.com/react-community/react-navigation/pull/2492
      if (navigation.state.index === 0) {
        navigation.navigate('DrawerOpen')
      } else {
        navigation.navigate('DrawerClose')
      }
    }}>Menu</Text>
  })
})

// login stack
const LoginStack = StackNavigator({
  loginScreen: { screen: LoginScreen },
  signupScreen: { screen: SignupScreen },
  forgottenPasswordScreen: { screen: ForgottenPasswordScreen, navigationOptions: { title: 'Forgot Password' } }
}, {
  headerMode: 'float',
  navigationOptions: {
    headerStyle: {backgroundColor: 'red'},
    title: 'You are not logged in'
  }
})

// Manifest of possible screens
const PrimaryNav = StackNavigator({
  loginStack: { screen: LoginStack },
  drawerStack: { screen: DrawerNavigation }
}, {
  // Default config for all screens
  headerMode: 'none',
  title: 'Main',
  initialRouteName: 'loginStack',
  transitionConfig: noTransitionConfig
})

export default PrimaryNav