/**

 * Functionality specific to Twenty Thirteen.

 *

 * Provides helper functions to enhance the theme experience.

 */

( function( $ ) {

	var body    = $( 'body' ),

	    _window = $( window );

	/**

	 * Adds a top margin to the footer if the sidebar widget area is higher

	 * than the rest of the page, to help the footer always visually clear

	 * the sidebar.

	 */

	$( function() {

		if ( body.is( '.sidebar' ) ) {

			var sidebar   = $( '#secondary .widget-area' ),

			    secondary = ( 0 == sidebar.length ) ? -40 : sidebar.height(),

			    margin    = $( '#tertiary .widget-area' ).height() - $( '#content' ).height() - secondary;

			if ( margin > 0 && _window.innerWidth() > 999 )

				$( '#colophon' ).css( 'margin-top', margin + 'px' );

		}

	} );

	/**

	 * Enables menu toggle for small screens.

	 */

	( function() {

		var nav = $( '#site-navigation' ), button, menu;

		if ( ! nav )

			return;

		button = nav.find( '.menu-toggle' );

		if ( ! button )

			return;

		// Hide button if menu is missing or empty.

		menu = nav.find( '.nav-menu' );

		if ( ! menu || ! menu.children().length ) {

			button.hide();

			return;

		}

		$( '.menu-toggle' ).on( 'click.twentythirteen', function() {

			nav.toggleClass( 'toggled-on' );

		} );

	} )();

	/**

	 * Makes "skip to content" link work correctly in IE9 and Chrome for better

	 * accessibility.

	 *

	 * @link http://www.nczonline.net/blog/2013/01/15/fixing-skip-to-content-links/

	 */

	_window.on( 'hashchange.twentythirteen', function() {

		var element = document.getElementById( location.hash.substring( 1 ) );

		if ( element ) {

			if ( ! /^(?:a|select|input|button|textarea)$/i.test( element.tagName ) )

				element.tabIndex = -1;

			element.focus();

		}

	} );

	/**

	 * Arranges footer widgets vertically.

	 */

	if ( $.isFunction( $.fn.masonry ) ) {

		var columnWidth = body.is( '.sidebar' ) ? 228 : 245;

		$( '#secondary .widget-area' ).masonry( {

			itemSelector: '.widget',

			columnWidth: columnWidth,

			gutterWidth: 20,

			isRTL: body.is( '.rtl' )

		} );

	}

} )( jQuery );