/**

 * @output wp-includes/js/wp-emoji-loader.js

 */

( function( window, document, settings ) {

	var src, ready, ii, tests;

	// Create a canvas element for testing native browser support of emoji.

	var canvas = document.createElement( 'canvas' );

	var context = canvas.getContext && canvas.getContext( '2d' );

	/**

	 * Checks if two sets of Emoji characters render the same visually.

	 *

	 * @since 4.9.0

	 *

	 * @private

	 *

	 * @param {number[]} set1 Set of Emoji character codes.

	 * @param {number[]} set2 Set of Emoji character codes.

	 *

	 * @return {boolean} True if the two sets render the same.

	 */

	function emojiSetsRenderIdentically( set1, set2 ) {

		var stringFromCharCode = String.fromCharCode;

		// Cleanup from previous test.

		context.clearRect( 0, 0, canvas.width, canvas.height );

		context.fillText( stringFromCharCode.apply( this, set1 ), 0, 0 );

		var rendered1 = canvas.toDataURL();

		// Cleanup from previous test.

		context.clearRect( 0, 0, canvas.width, canvas.height );

		context.fillText( stringFromCharCode.apply( this, set2 ), 0, 0 );

		var rendered2 = canvas.toDataURL();

		return rendered1 === rendered2;

	}

	/**

	 * Detects if the browser supports rendering emoji or flag emoji.

	 *

	 * Flag emoji are a single glyph made of two characters, so some browsers

	 * (notably, Firefox OS X) don't support them.

	 *

	 * @since 4.2.0

	 *

	 * @private

	 *

	 * @param {string} type Whether to test for support of "flag" or "emoji".

	 *

	 * @return {boolean} True if the browser can render emoji, false if it cannot.

	 */

	function browserSupportsEmoji( type ) {

		var isIdentical;

		if ( ! context || ! context.fillText ) {

			return false;

		}

		/*

		 * Chrome on OS X added native emoji rendering in M41. Unfortunately,

		 * it doesn't work when the font is bolder than 500 weight. So, we

		 * check for bold rendering support to avoid invisible emoji in Chrome.

		 */

		context.textBaseline = 'top';

		context.font = '600 32px Arial';

		switch ( type ) {

			case 'flag':

				/*

				 * Test for UN flag compatibility. This is the least supported of the letter locale flags,

				 * so gives us an easy test for full support.

				 *

				 * To test for support, we try to render it, and compare the rendering to how it would look if

				 * the browser doesn't render it correctly ([U] + [N]).

				 */

				isIdentical = emojiSetsRenderIdentically(

					[ 0xD83C, 0xDDFA, 0xD83C, 0xDDF3 ],

					[ 0xD83C, 0xDDFA, 0x200B, 0xD83C, 0xDDF3 ]

				);

				if ( isIdentical ) {

					return false;

				}

				/*

				 * Test for English flag compatibility. England is a country in the United Kingdom, it

				 * does not have a two letter locale code but rather an five letter sub-division code.

				 *

				 * To test for support, we try to render it, and compare the rendering to how it would look if

				 * the browser doesn't render it correctly (black flag emoji + [G] + [B] + [E] + [N] + [G]).

				 */

				isIdentical = emojiSetsRenderIdentically(

					[ 0xD83C, 0xDFF4, 0xDB40, 0xDC67, 0xDB40, 0xDC62, 0xDB40, 0xDC65, 0xDB40, 0xDC6E, 0xDB40, 0xDC67, 0xDB40, 0xDC7F ],

					[ 0xD83C, 0xDFF4, 0x200B, 0xDB40, 0xDC67, 0x200B, 0xDB40, 0xDC62, 0x200B, 0xDB40, 0xDC65, 0x200B, 0xDB40, 0xDC6E, 0x200B, 0xDB40, 0xDC67, 0x200B, 0xDB40, 0xDC7F ]

				);

				return ! isIdentical;

			case 'emoji':

				/*

				 *

				 *

				 * When updating this test for future Emoji releases, ensure that individual emoji that make up the

				 * sequence come from older emoji standards.

				 */

				isIdentical = emojiSetsRenderIdentically(

				);

				return ! isIdentical;

		}

		return false;

	}

	/**

	 * Adds a script to the head of the document.

	 *

	 * @ignore

	 *

	 * @since 4.2.0

	 *

	 * @param {Object} src The url where the script is located.

	 * @return {void}

	 */

	function addScript( src ) {

		var script = document.createElement( 'script' );

		script.src = src;

		script.defer = script.type = 'text/javascript';

		document.getElementsByTagName( 'head' )[0].appendChild( script );

	}

	tests = Array( 'flag', 'emoji' );

	settings.supports = {

		everything: true,

		everythingExceptFlag: true

	};

	/*

	 * Tests the browser support for flag emojis and other emojis, and adjusts the

	 * support settings accordingly.

	 */

	for( ii = 0; ii < tests.length; ii++ ) {

		settings.supports[ tests[ ii ] ] = browserSupportsEmoji( tests[ ii ] );

		settings.supports.everything = settings.supports.everything && settings.supports[ tests[ ii ] ];

		if ( 'flag' !== tests[ ii ] ) {

			settings.supports.everythingExceptFlag = settings.supports.everythingExceptFlag && settings.supports[ tests[ ii ] ];

		}

	}

	settings.supports.everythingExceptFlag = settings.supports.everythingExceptFlag && ! settings.supports.flag;

	// Sets DOMReady to false and assigns a ready function to settings.

	settings.DOMReady = false;

	settings.readyCallback = function() {

		settings.DOMReady = true;

	};

	// When the browser can not render everything we need to load a polyfill.

	if ( ! settings.supports.everything ) {

		ready = function() {

			settings.readyCallback();

		};

		/*

		 * Cross-browser version of adding a dom ready event.

		 */

		if ( document.addEventListener ) {

			document.addEventListener( 'DOMContentLoaded', ready, false );

			window.addEventListener( 'load', ready, false );

		} else {

			window.attachEvent( 'onload', ready );

			document.attachEvent( 'onreadystatechange', function() {

				if ( 'complete' === document.readyState ) {

					settings.readyCallback();

				}

			} );

		}

		src = settings.source || {};

		if ( src.concatemoji ) {

			addScript( src.concatemoji );

		} else if ( src.wpemoji && src.twemoji ) {

			addScript( src.twemoji );

			addScript( src.wpemoji );

		}

	}

} )( window, document, window._wpemojiSettings );