/**

 * @output wp-includes/js/wp-a11y.js

 */

/** @namespace wp */

window.wp = window.wp || {};

( function ( wp, $ ) {

	'use strict';

	var $containerPolite,

		$containerAssertive,

		previousMessage = '';

	/**

	 * Update the ARIA live notification area text node.

	 *

	 * @since 4.2.0

	 * @since 4.3.0 Introduced the 'ariaLive' argument.

	 *

	 * @param {String} message    The message to be announced by Assistive Technologies.

	 * @param {String} [ariaLive] The politeness level for aria-live. Possible values:

	 *                            polite or assertive. Default polite.

	 * @returns {void}

	 */

	function speak( message, ariaLive ) {

		// Clear previous messages to allow repeated strings being read out.

		clear();

		// Remove HTML tags, ensuring only text is sent to screen readers.

		message = wp.sanitize.stripTagsAndEncodeText( message );

		/*

		 * Safari 10+VoiceOver don't announce repeated, identical strings. We use

		 * a `no-break space` to force them to think identical strings are different.

		 * See ticket #36853.

		 */

		if ( previousMessage === message ) {

			message = message + '\u00A0';

		}

		previousMessage = message;

		if ( $containerAssertive && 'assertive' === ariaLive ) {

			$containerAssertive.text( message );

		} else if ( $containerPolite ) {

			$containerPolite.text( message );

		}

	}

	/**

	 * Build the live regions markup.

	 *

	 * @since 4.3.0

	 *

	 * @param {String} ariaLive Optional. Value for the 'aria-live' attribute, default 'polite'.

	 *

	 * @return {Object} $container The ARIA live region jQuery object.

	 */

	function addContainer( ariaLive ) {

		ariaLive = ariaLive || 'polite';

		var $container = $( '<div>', {

			'id': 'wp-a11y-speak-' + ariaLive,

			'aria-live': ariaLive,

			'aria-relevant': 'additions text',

			'aria-atomic': 'true',

			'class': 'screen-reader-text wp-a11y-speak-region'

		});

		$( document.body ).append( $container );

		return $container;

	}

	/**

	 * Clear the live regions.

	 *

	 * @since 4.3.0

	 */

	function clear() {

		$( '.wp-a11y-speak-region' ).text( '' );

	}

	/**

	 * Initialize wp.a11y and define ARIA live notification area.

	 *

	 * @since 4.2.0

	 * @since 4.3.0 Added the assertive live region.

	 */

	$( document ).ready( function() {

		$containerPolite = $( '#wp-a11y-speak-polite' );

		$containerAssertive = $( '#wp-a11y-speak-assertive' );

		if ( ! $containerPolite.length ) {

			$containerPolite = addContainer( 'polite' );

		}

		if ( ! $containerAssertive.length ) {

			$containerAssertive = addContainer( 'assertive' );

		}

	});

	/** @namespace wp.a11y */

	wp.a11y = wp.a11y || {};

	wp.a11y.speak = speak;

}( window.wp, window.jQuery ));