/**
 * File navigation.js.
 *
 * Handles toggling the navigation menu for small screens and enables TAB key
 * navigation support for dropdown menus.
 */
(function () {
	var container, button, menu, links, i, len;

	container = document.getElementById("site-nav-wrap");
	nav_tag = document.querySelector(".main-navigation");
	if (!container) {
		return;
	}

	button = container.getElementsByTagName("button")[0];
	if ("undefined" === typeof button) {
		return;
	}

	menu = container.getElementsByTagName("ul")[0];

	// Hide menu toggle button if menu is empty and return early.
	if ("undefined" === typeof menu) {
		button.style.display = "none";
		return;
	}

	menu.setAttribute("aria-expanded", "false");
	if (-1 === menu.className.indexOf("nav-menu")) {
		menu.className += " nav-menu";
	}

	button.onclick = function () {
		if (-1 !== nav_tag.className.indexOf("toggled")) {
			nav_tag.className = nav_tag.className.replace(" toggled", "");
			button.setAttribute("aria-expanded", "false");
			menu.setAttribute("aria-expanded", "false");
		} else {
			nav_tag.className += " toggled";
			button.setAttribute("aria-expanded", "true");
			menu.setAttribute("aria-expanded", "true");
		}
	};

	// Get all the link elements within the menu.
	links = menu.getElementsByTagName("a");

	// Each time a menu link is focused or blurred, toggle focus.
	for (i = 0, len = links.length; i < len; i++) {
		links[i].addEventListener("focus", toggleFocus, true);
		links[i].addEventListener("blur", toggleFocus, true);
	}

	/**
	 * Sets or removes .focus class on an element.
	 */
	function toggleFocus() {
		var self = this;

		// Move up through the ancestors of the current link until we hit .nav-menu.
		while (-1 === self.className.indexOf("nav-menu")) {
			// On li elements toggle the class .focus.
			if ("li" === self.tagName.toLowerCase()) {
				if (-1 !== self.className.indexOf("focus")) {
					self.className = self.className.replace(" focus", "");
				} else {
					self.className += " focus";
				}
			}

			self = self.parentElement;
		}
	}

	/**
	 * Toggles `focus` class to allow submenu access on tablets.
	 */
	(function (container) {
		var touchStartFn,
			i,
			parentLink = container.querySelectorAll(
				".menu-item-has-children > a, .page_item_has_children > a"
			);
		if ("ontouchstart" in window) {
			touchStartFn = function (e) {
				var menuItem = this.parentNode,
					i;
				if (!menuItem.classList.contains("focus")) {
					e.preventDefault();
					for (i = 0; i < menuItem.parentNode.children.length; ++i) {
						if (menuItem === menuItem.parentNode.children[i]) {
							continue;
						}
						menuItem.parentNode.children[i].classList.remove("focus");
					}
					menuItem.classList.add("focus");
				} else {
					menuItem.classList.remove("focus");
				}
			};

			for (i = 0; i < parentLink.length; ++i) {
				parentLink[i].addEventListener("touchstart", touchStartFn, false);
			}
		}
	})(container);
})();