class Navigation {
	static initialize() {
		Navigation.allSubviews = [ ];

		Navigation.element = document.body.querySelector("tab-bar");

		//Process the tab bar like a view controller.
		UIKit.processViewControllerElement(Navigation.element, Navigation);

		Navigation.barItems = document.body.querySelectorAll("tab-bar bar-button-item:not(.user-menu-button)");

		for (var i = 0; i < Navigation.barItems.length; i++) {
			Navigation.barItems[i].addEventListener("click", Navigation.onBarItemSelected);
		}

		Navigation.onHashChanged();
	}

	/**
	 * Hides all elements from the navigation that should not be visible on the login screen.
	 */
	static displayForLogin() {
		Navigation.element.classList.add("login-view");
	}

	/**
	 * Shows all elements again that were not visible on the login screen.
	 */
	static endDisplayForLogin() {
		Navigation.element.classList.remove("login-view");
	}

	static onHashChanged(event) {
		var hash = window.location.hash;

		for (var i = 0; i < Navigation.barItems.length; i++) {
			var item = Navigation.barItems[i];

			if (item.getAttribute("target") == hash) {
				if (item.className.indexOf("active") == -1) {
					item.classList.add("active");
				}
			}
			else {
				item.classList.remove("active");
			}
		}
	}

	static onBarItemSelected(event) {
		var target = event.currentTarget.getAttribute("target");

		if (!target) {
			return;
		}

		if (target.startsWith("#")) {
			window.location.hash = target;
			return;
		}
	}

	static onUserIconClicked(event) {
		var userMenu = UIKit.getPopoverById("user-menu");

		//Inform the context menu about the summoning view controller and view.
		userMenu.setViewController(Navigation);
		//userMenu.setView(Navigation);

		userMenu.showForElement(event.currentTarget, "right");

		event.stopPropagation();
	}

	static onLogOutMenuItemPressed(event) {
		Authentication.logOut();
	}
}

window.addEventListener("hashchange", Navigation.onHashChanged);