EDIT

package eu.etaxonomy.vaadin.ui.mainmenu;

import java.util.List;

import java.util.Optional;

import java.util.stream.Collectors;

import java.util.stream.StreamSupport;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.context.ApplicationEventPublisher;

import org.springframework.context.event.EventListener;

import com.vaadin.server.FontAwesome;

import com.vaadin.server.Resource;

import com.vaadin.spring.annotation.SpringComponent;

import com.vaadin.spring.annotation.UIScope;

import com.vaadin.ui.Button;

import com.vaadin.ui.CssLayout;

import com.vaadin.ui.themes.ValoTheme;

import eu.etaxonomy.vaadin.ui.MainMenu;

import eu.etaxonomy.vaadin.ui.navigation.AfterViewChangeEvent;

import eu.etaxonomy.vaadin.ui.navigation.NavigationEvent;

/**

 * ValoMainMenuBean is the implementation of responsive Vaadin Valo theme's menu

 *

 * @author Peter / Vaadin

 */

@SpringComponent

@UIScope

class ValoMainMenuBean extends CssLayout implements MainMenu {

	private static final long serialVersionUID = -993548217313748689L;

	private final static String MENU_VISIBLE = "valo-menu-visible";

	private CssLayout menuArea;

	private Button menuToggle;

	@Autowired

    ApplicationEventPublisher eventBus;

	public ValoMainMenuBean() {

		setPrimaryStyleName(ValoTheme.MENU_ROOT);

		CssLayout menuPart = new CssLayout();

		menuPart.addStyleName(ValoTheme.MENU_PART);

		menuToggle = new Button("Menu", FontAwesome.LIST);

		menuToggle.addClickListener(e -> onToggleMenu());

		menuToggle.addStyleName("valo-menu-toggle");

		menuToggle.addStyleName(ValoTheme.BUTTON_SMALL);

		menuPart.addComponent(menuToggle);

		menuArea = new CssLayout();

		menuArea.setPrimaryStyleName("valo-menuitems");

		menuArea.setWidth(100, Unit.PERCENTAGE);

		menuPart.addComponent(menuArea);

		addComponent(menuPart);

	}

	private void onToggleMenu() {

		if (getStyleName().contains(MENU_VISIBLE)) {

			removeStyleName(MENU_VISIBLE);

		} else {

			addStyleName(MENU_VISIBLE);

		}

	}

	@Override

	public MainMenuItem addMenuItem(String caption, Resource icon, String navigationResource) {

		MainMenuItemBean mainMenuItem = new MainMenuItemBean(caption, icon, navigationResource,

				e -> onMenuItemClicked(navigationResource));

		menuArea.addComponent(mainMenuItem);

		return mainMenuItem;

	}

	private void onMenuItemClicked(String navigationResource) {

	    eventBus.publishEvent(new NavigationEvent(navigationResource));

	}

	@EventListener

	protected void onNavigationEvent(NavigationEvent e) {

		List<MainMenuItemBean> menuItems = StreamSupport.stream(menuArea.spliterator(), false)

				.filter(component -> MainMenuItemBean.class.isAssignableFrom(component.getClass()))

				.map(component -> MainMenuItemBean.class.cast(component)).collect(Collectors.toList());

		menuItems.forEach(menuItem -> menuItem.setSelected(false));

		Optional<MainMenuItemBean> selectedMenuItem = menuItems.stream()

				.filter(menuItem -> menuItem.getViewName().equals(e.getViewName())).findFirst();

		if (selectedMenuItem.isPresent()) {

			selectedMenuItem.get().setSelected(true);

		}

	}

	@EventListener

	protected void afterViewChange(AfterViewChangeEvent event) {

		removeStyleName(MENU_VISIBLE);

	}

}