/**
 * navigation.js
 *
 * Handles toggling the navigation menu for small screens.
 */
( function() {
    var container, button, menu, link;

    container = document.getElementById( 'site-navigation' );
    if ( ! container ) {
        return;
    }

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

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

    link = container.getElementsByTagName( 'li' )[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 !== container.className.indexOf( 'toggled' ) ) {
            container.className = container.className.replace( ' toggled', '' );
            button.setAttribute( 'aria-expanded', 'false' );
            menu.setAttribute( 'aria-expanded', 'false' );
        } else {
            container.className += ' toggled';
            button.setAttribute( 'aria-expanded', 'true' );
            menu.setAttribute( 'aria-expanded', 'true' );
        }
    };

    link.onclick = function() {
        container.className = container.className.replace( ' toggled', '' );
        button.setAttribute( 'aria-expanded', 'false' );
        menu.setAttribute( 'aria-expanded', 'false' );
    };
} )();