/**

 * Emoji Settings as exported in PHP via _print_emoji_detection_script().

 * @typedef WPEmojiSettings

 * @type {object}

 * @property {?object} source

 * @property {?string} source.concatemoji

 * @property {?string} source.twemoji

 * @property {?string} source.wpemoji

 * @property {?boolean} DOMReady

 * @property {?Function} readyCallback

 */

/**

 * Support tests.

 * @typedef SupportTests

 * @type {object}

 * @property {?boolean} flag

 * @property {?boolean} emoji

 */

/**

 * IIFE to detect emoji support and load Twemoji if needed.

 *

 * @param {Window} window

 * @param {Document} document

 * @param {WPEmojiSettings} settings

 */

( function wpEmojiLoader( window, document, settings ) {

	if ( typeof Promise === 'undefined' ) {

		return;

	}

	var sessionStorageKey = 'wpEmojiSettingsSupports';

	var tests = [ 'flag', 'emoji' ];

	/**

	 * Checks whether the browser supports offloading to a Worker.

	 *

	 * @since 6.3.0

	 *

	 * @private

	 *

	 * @returns {boolean}

	 */

	function supportsWorkerOffloading() {

		return (

			typeof Worker !== 'undefined' &&

			typeof OffscreenCanvas !== 'undefined' &&

			typeof URL !== 'undefined' &&

			URL.createObjectURL &&

			typeof Blob !== 'undefined'

		);

	}

	/**

	 * @typedef SessionSupportTests

	 * @type {object}

	 * @property {number} timestamp

	 * @property {SupportTests} supportTests

	 */

	/**

	 * Get support tests from session.

	 *

	 * @since 6.3.0

	 *

	 * @private

	 *

	 * @returns {?SupportTests} Support tests, or null if not set or older than 1 week.

	 */

	function getSessionSupportTests() {

		try {

			/** @type {SessionSupportTests} */

			var item = JSON.parse(

				sessionStorage.getItem( sessionStorageKey )

			);

			if (

				typeof item === 'object' &&

				typeof item.timestamp === 'number' &&

				new Date().valueOf() < item.timestamp + 604800 && // Note: Number is a week in seconds.

				typeof item.supportTests === 'object'

			) {

				return item.supportTests;

			}

		} catch ( e ) {}

		return null;

	}

	/**

	 * Persist the supports in session storage.

	 *

	 * @since 6.3.0

	 *

	 * @private

	 *

	 * @param {SupportTests} supportTests Support tests.

	 */

	function setSessionSupportTests( supportTests ) {

		try {

			/** @type {SessionSupportTests} */

			var item = {

				supportTests: supportTests,

				timestamp: new Date().valueOf()

			};

			sessionStorage.setItem(

				sessionStorageKey,

				JSON.stringify( item )

			);

		} catch ( e ) {}

	}

	 * This function may be serialized to run in a Worker. Therefore, it cannot refer to variables from the containing

	 * scope. Everything must be passed by parameters.

	 *

	 * @param {CanvasRenderingContext2D} context 2D Context.

	 * @param {string} set1 Set of Emoji to test.

	 * @param {string} set2 Set of Emoji to test.

	function emojiSetsRenderIdentically( context, set1, set2 ) {

		// Cleanup from previous test.

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

		context.fillText( set1, 0, 0 );

		var rendered1 = new Uint32Array(

			context.getImageData(

				0,

				0,

				context.canvas.width,

				context.canvas.height

			).data

		);

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

		context.fillText( set2, 0, 0 );

		var rendered2 = new Uint32Array(

			context.getImageData(

				0,

				0,

				context.canvas.width,

				context.canvas.height

			).data

		);

		return rendered1.every( function ( rendered2Data, index ) {

			return rendered2Data === rendered2[ index ];

		} );

	 * Determines if the browser properly renders Emoji that Twemoji can supplement.

	 * This function may be serialized to run in a Worker. Therefore, it cannot refer to variables from the containing

	 * scope. Everything must be passed by parameters.

	 * @param {CanvasRenderingContext2D} context 2D Context.

	 * @param {Function} emojiSetsRenderIdentically Reference to emojiSetsRenderIdentically function, needed due to minification.

	function browserSupportsEmoji( context, type, emojiSetsRenderIdentically ) {

				 * Test for Transgender flag compatibility. Added in Unicode 13.

					context,

					'\uD83C\uDFF3\uFE0F\u200D\u26A7\uFE0F', // as a zero-width joiner sequence

					'\uD83C\uDFF3\uFE0F\u200B\u26A7\uFE0F' // separated by a zero-width space

					context,

					'\uD83C\uDDFA\uD83C\uDDF3', // as the sequence of two code points

					'\uD83C\uDDFA\u200B\uD83C\uDDF3' // as the two code points separated by a zero-width space

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

					context,

					// as the flag sequence

					'\uD83C\uDFF4\uDB40\uDC67\uDB40\uDC62\uDB40\uDC65\uDB40\uDC6E\uDB40\uDC67\uDB40\uDC7F',

					// with each code point separated by a zero-width space

					'\uD83C\uDFF4\u200B\uDB40\uDC67\u200B\uDB40\uDC62\u200B\uDB40\uDC65\u200B\uDB40\uDC6E\u200B\uDB40\uDC67\u200B\uDB40\uDC7F'

				 * Four and twenty blackbirds baked in a pie.

				 * To test for Emoji 15.0 support, try to render a new emoji: Blackbird.

				 * The Blackbird is a ZWJ sequence combining 🐦 Bird and ⬛ large black square.,

				 * 0x1F426 (\uD83D\uDC26) == Bird

				 * 0x2B1B == Large Black Square

					context,

					'\uD83D\uDC26\u200D\u2B1B', // as the zero-width joiner sequence

					'\uD83D\uDC26\u200B\u2B1B' // separated by a zero-width space

	 * Checks emoji support tests.

	 *

	 * This function may be serialized to run in a Worker. Therefore, it cannot refer to variables from the containing

	 * scope. Everything must be passed by parameters.

	 *

	 * @since 6.3.0

	 *

	 * @private

	 *

	 * @param {string[]} tests Tests.

	 * @param {Function} browserSupportsEmoji Reference to browserSupportsEmoji function, needed due to minification.

	 * @param {Function} emojiSetsRenderIdentically Reference to emojiSetsRenderIdentically function, needed due to minification.

	 *

	 * @return {SupportTests} Support tests.

	 */

	function testEmojiSupports( tests, browserSupportsEmoji, emojiSetsRenderIdentically ) {

		var canvas;

		if (

			typeof WorkerGlobalScope !== 'undefined' &&

			self instanceof WorkerGlobalScope

		) {

			canvas = new OffscreenCanvas( 300, 150 ); // Dimensions are default for HTMLCanvasElement.

		} else {

			canvas = document.createElement( 'canvas' );

		}

		var context = canvas.getContext( '2d', { willReadFrequently: true } );

		/*

		 * 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';

		var supports = {};

		tests.forEach( function ( test ) {

			supports[ test ] = browserSupportsEmoji( context, test, emojiSetsRenderIdentically );

		} );

		return supports;

	}

	/**

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

	 *

		script.defer = true;

		document.head.appendChild( script );

	// Create a promise for DOMContentLoaded since the worker logic may finish after the event has fired.

	var domReadyPromise = new Promise( function ( resolve ) {

		document.addEventListener( 'DOMContentLoaded', resolve, {

			once: true

		} );

	} );

	// Obtain the emoji support from the browser, asynchronously when possible.

	new Promise( function ( resolve ) {

		var supportTests = getSessionSupportTests();

		if ( supportTests ) {

			resolve( supportTests );

			return;

		if ( supportsWorkerOffloading() ) {

			try {

				// Note that the functions are being passed as arguments due to minification.

				var workerScript =

					'postMessage(' +

					testEmojiSupports.toString() +

					'(' +

					[

						JSON.stringify( tests ),

						browserSupportsEmoji.toString(),

						emojiSetsRenderIdentically.toString()

					].join( ',' ) +

					'));';

				var blob = new Blob( [ workerScript ], {

					type: 'text/javascript'

				} );

				var worker = new Worker( URL.createObjectURL( blob ), { name: 'wpTestEmojiSupports' } );

				worker.onmessage = function ( event ) {

					supportTests = event.data;

					setSessionSupportTests( supportTests );

					worker.terminate();

					resolve( supportTests );

				};

				return;

			} catch ( e ) {}

		supportTests = testEmojiSupports( tests, browserSupportsEmoji, emojiSetsRenderIdentically );

		setSessionSupportTests( supportTests );

		resolve( supportTests );

	} )

		// Once the browser emoji support has been obtained from the session, finalize the settings.

		.then( function ( supportTests ) {

			/*

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

			 * support settings accordingly.

			 */

			for ( var test in supportTests ) {

				settings.supports[ test ] = supportTests[ test ];

				settings.supports.everything =

					settings.supports.everything && settings.supports[ test ];

				if ( 'flag' !== test ) {

					settings.supports.everythingExceptFlag =

						settings.supports.everythingExceptFlag &&

						settings.supports[ test ];

				}

			}