MediaWiki:Gadget-I18n-js.js

/* <nowiki>
 * Library for accessing i18n messages for use in Dev Wiki scripts.
 * See [[I18n-js]] for documentation.
 *
 * @author Cqm <https://dev.fandom.com/User:Cqm>
 * @author OneTwoThreeFall <https://dev.fandom.com/User:OneTwoThreeFall>
 *
 * @version 0.6.7
 *
 * @notes Also used by SOAP Wiki for their reporting forms (with a non-dev i18n.json page)
 * @notes This is apparently a commonly used library for a number of scripts and also
 *   includes a check to prevent double loading. This can make it painful to test from your JS
 *   console. To get around this, add ?usesitejs=0&useuserjs=0 to your URL.
 * @notes Coding convensions:
 *   https://www.mediawiki.org/wiki/Manual:Coding_conventions/JavaScript
 */

/* global mediaWiki */

/* jshint bitwise:true, camelcase:true, curly:true, eqeqeq:true, es3:false,
     forin:true, immed:true, indent:4, latedef:true, newcap:true,
     noarg:true, noempty:true, nonew:true, plusplus:true, quotmark:single,
     undef:true, unused:true, strict:true, trailing:true,
     browser:true, devel:false, jquery:true,
     onevar:true
 */

( function ( window, $, mw, undefined ) {
	'use strict';

	window.dev = window.dev || {};
	window.dev.i18n = window.dev.i18n || {};

	/* Prevent double loading and loss of cache */
	if ( window.dev.i18n.loadMessages !== undefined ) {
		return;
	}

	/*
	 * Cache of mw config variables.
	 *
	 * @var {object} conf Cache of mw config variables:
	 * - {boolean} debug
	 * - {string} wgContentLanguage Site language
	 *     Be careful to use this:
	 *     - In languages with variants, this will block the language conversion;
	 *       see <https://www.mediawiki.org/wiki/Writing_systems>.
	 *     - In multilingual wikis like "Feed The Beast", this will block both the
	 *       multilingual content providing and language conversion.
	 * - {string} wgPageContentLanguage Page Language or Content Modal Language
	 *     or Site Language or 'en'
	 *     Be careful to use this:
	 *     - In Special: pages, this will be the user language.
	 *     - In Module: pages, this will be the content modal language 'en'.
	 * - {string} wgUserLanguage
	 * - {(string|null)} wgUserVariant The language variant user currently using,
	 *     'null' when the page lannguage doesn't have language variants.
	 */
	var conf = mw.config.get( [
		'debug',
		'wgContentLanguage',
		'wgPageContentLanguage',
		'wgUserLanguage',
		'wgUserVariant'
	] ),

		/*
		 * @var {number} Current time in milliseconds, used to set and check cache age.
		 */
		now = Date.now(),

		/*
		 * @var {number} Length of one day in milliseconds, used in cache age calculations.
		 */
		oneDay = 1000 * 60 * 60 * 24,

		/*
		 * @var {string} Prefix used for localStorage keys that contain i18n-js cache data
		 */
		cachePrefix = 'i18n-cache-',

		/*
		 * @var {boolean} Whether a fallback loop warning been shown
		 */
		warnedAboutFallbackLoop = false,

		/*
		 * @var {object} Cache of loaded I18n instances.
		 */
		cache = {},

		/*
		 * Initial overrides object, initialised below with the i18n global variable.
		 * Allows end-users to override specific messages. See documentation for how to use.
		 *
		 * @var {(null|object)} overrides
		 */
		overrides = null,

		/*
		 * Mapping of deprecated language codes that were used in previous
		 * versions of MediaWiki to up-to-date, current language codes.
		 *
		 * These codes shouldn't be used to store translations unless there are language
		 * changes to /includes/language/LanguageCode.php in mediawiki/core.
		 *
		 * These may or may not be valid BCP 47 codes; they are included here
		 * because MediaWiki renamed these particular codes at some point.
		 *
		 * Note that 'als' is actually a valid ISO 639 code (Tosk Albanian), but it
		 * was previously used in MediaWiki for Alsatian, which comes under 'gsw'.
		 *
		 * @var {object.<string, string>} Mapping from deprecated MediaWiki-internal language code
		 *   to replacement MediaWiki-internal language code.
		 *
		 * @see /includes/language/LanguageCode.php in MediaWiki core
		 * @see https://meta.wikimedia.org/wiki/Special_language_codes
		 */
		deprecatedCodes = {
			'als': 'gsw', // T25215
			'bat-smg': 'sgs', // T27522
			'be-x-old': 'be-tarask', // T11823
			'fiu-vro': 'vro', // T31186
			'roa-rup': 'rup', // T17988
			'zh-classical': 'lzh', // T30443
			'zh-min': 'nan',
			'zh-min-n': 'nan',
			'zh-min-nan': 'nan', // T30442
			'zh-yue': 'yue' // T30441
		},


		/**
		 * Mapping of non-standard language codes used in MediaWiki to
		 * standardized BCP 47 codes.
		 *
		 * @var {object.<string, string>} Mapping from nonstandard MediaWiki-internal codes to
		 *   BCP 47 codes
		 *
		 * @see /includes/language/LanguageCode.php in MediaWiki core
		 * @see https://meta.wikimedia.org/wiki/Special_language_codes
		 * @see https://phabricator.wikimedia.org/T125073
		 */
		nonStandardCodes = {
			'cbk-zam': 'cbk', // T124657
			'de-formal': 'de-x-formal',
			'eml': 'egl', // T36217
			'en-rtl': 'en-x-rtl',
			'es-formal': 'es-x-formal',
			'hu-formal': 'hu-x-formal',
			'kk-cn': 'kk-Arab-CN',
			'kk-kz': 'kk-Cyrl-KZ',
			'kk-tr': 'kk-Latn-TR',
			'map-bms': 'jv-x-bms', // [[wikipedia:en:Banyumasan_dialect]] T125073
			'mo': 'ro-Cyrl-MD', // T125073
			'nrm': 'nrf', // [[wikipedia:en:Norman_language]] T25216
			'nl-informal': 'nl-x-informal',
			'roa-tara': 'nap-x-tara', // [[wikipedia:en:Tarantino_dialect]]
			'simple': 'en-x-simple',
			'sr-ec': 'sr-Cyrl', // T117845
			'sr-el': 'sr-Latn', // T117845
			'zh-cn': 'zh-Hans-CN',
			'zh-sg': 'zh-Hans-SG',
			'zh-my': 'zh-Hans-MY',
			'zh-tw': 'zh-Hant-TW',
			'zh-hk': 'zh-Hant-HK',
			'zh-mo': 'zh-Hant-MO'
		},

		/*
		 * Language fallbacks for those that don't fallback to English.
		 *
		 * Shouldn't need updating unless there're language fallback chain changes
		 * to /languages/messages files in mediawiki/core.
		 *
		 * To generate this, use `$ grep -R "fallback =" /path/to/messages/`,
		 * pipe the result to a text file and format the result.
		 *
		 * Please note that there's bidirectional/multidirectional fallback in languages,
		 * including cdo <=> nan, pt <=> pt-br, zh <=> zh-hans <=> zh-hant
		 *
		 * @var {object.<string, string[]>} Mapping from language codes to fallback language codes
		 */
		fallbacks = {
			'ab': [ 'ru' ],
			'abs': [ 'id' ],
			'ace': [ 'id' ],
			'ady': [ 'ady-cyrl' ],
			'aeb': [ 'aeb-arab' ],
			'aeb-arab': [ 'ar' ],
			'aln': [ 'sq' ],
			'alt': [ 'ru' ],
			'ami': [ 'zh-tw', 'zh-hant', 'zh', 'zh-hans' ],
			'an': [ 'es' ],
			'anp': [ 'hi' ],
			'arn': [ 'es' ],
			'arq': [ 'ar' ],
			'ary': [ 'ar' ],
			'arz': [ 'ar' ],
			'ast': [ 'es' ],
			'atj': [ 'fr' ],
			'av': [ 'ru' ],
			'avk': [ 'fr', 'es', 'ru' ],
			'awa': [ 'hi' ],
			'ay': [ 'es' ],
			'azb': [ 'fa' ],
			'ba': [ 'ru' ],
			'ban': [ 'id' ],
			'ban-bali': [ 'ban' ],
			'bar': [ 'de' ],
			'bbc': [ 'bbc-latn' ],
			'bbc-latn': [ 'id' ],
			'bcc': [ 'fa' ],
			'bci': [ 'fr' ],
			'be-tarask': [ 'be' ],
			'bgn': [ 'fa' ],
			'bh': [ 'bho' ],
			'bi': [ 'en' ],
			'bjn': [ 'id' ],
			'blk': [ 'my' ],
			'bm': [ 'fr' ],
			'bpy': [ 'bn' ],
			'bqi': [ 'fa' ],
			'br': [ 'fr' ],
			'btm': [ 'id' ],
			'bug': [ 'id' ],
			'bxr': [ 'ru' ],
			'ca': [ 'oc' ],
			'cbk-zam': [ 'es' ],
			'cdo': [ 'nan', 'zh-hant', 'zh', 'zh-hans' ],
			'ce': [ 'ru' ],
			'co': [ 'it' ],
			'crh': [ 'crh-latn' ],
			'crh-cyrl': [ 'ru' ],
			'cs': [ 'sk' ],
			'csb': [ 'pl' ],
			'cv': [ 'ru' ],
			'de-at': [ 'de' ],
			'de-ch': [ 'de' ],
			'de-formal': [ 'de' ],
			'dsb': [ 'hsb', 'de' ],
			'dtp': [ 'ms' ],
			'dty': [ 'ne' ],
			'egl': [ 'it' ],
			'eml': [ 'it' ],
			'es-formal': [ 'es' ],
			'ext': [ 'es' ],
			'ff': [ 'fr' ],
			'fit': [ 'fi' ],
			'fon': [ 'fr' ],
			'frc': [ 'fr' ],
			'frp': [ 'fr' ],
			'frr': [ 'de' ],
			'fur': [ 'it' ],
			'gag': [ 'tr' ],
			'gan': [ 'gan-hant', 'gan-hans', 'zh-hant', 'zh', 'zh-hans' ],
			'gan-hans': [ 'gan', 'gan-hant', 'zh-hans', 'zh', 'zh-hant' ],
			'gan-hant': [ 'gan', 'gan-hans', 'zh-hant', 'zh', 'zh-hans' ],
			'gcr': [ 'fr' ],
			'gl': [ 'pt' ],
			'gld': [ 'ru' ],
			'glk': [ 'fa' ],
			'gn': [ 'es' ],
			'gom': [ 'gom-deva' ],
			'gom-deva': [ 'hi' ],
			'gor': [ 'id' ],
			'gsw': [ 'de' ],
			'guc': [ 'es' ],
			'hak': [ 'zh-hant', 'zh', 'zh-hans' ],
			'hif': [ 'hif-latn' ],
			'hrx': [ 'de' ],
			'hsb': [ 'dsb', 'de' ],
			'hsn': [ 'zh-cn', 'zh-hans', 'zh', 'zh-hant' ],
			'ht': [ 'fr' ],
			'hu-formal': [ 'hu' ],
			'hyw': [ 'hy' ],
			'ii': [ 'zh-cn', 'zh-hans', 'zh', 'zh-hant' ],
			'inh': [ 'ru' ],
			'io': [ 'eo' ],
			'iu': [ 'ike-cans' ],
			'jam': [ 'en' ],
			'jut': [ 'da' ],
			'jv': [ 'id' ],
			'kaa': [ 'kk-latn', 'kk-cyrl' ],
			'kab': [ 'fr' ],
			'kbd': [ 'kbd-cyrl' ],
			'kbp': [ 'fr' ],
			'kea': [ 'pt' ],
			'khw': [ 'ur' ],
			'kiu': [ 'tr' ],
			'kjp': [ 'my' ],
			'kk': [ 'kk-cyrl' ],
			'kk-arab': [ 'kk-cyrl' ],
			'kk-cn': [ 'kk-arab', 'kk-cyrl' ],
			'kk-kz': [ 'kk-cyrl' ],
			'kk-latn': [ 'kk-cyrl' ],
			'kk-tr': [ 'kk-latn', 'kk-cyrl' ],
			'kl': [ 'da' ],
			'koi': [ 'ru' ],
			'ko-kp': [ 'ko' ],
			'krc': [ 'ru' ],
			'krl': [ 'fi' ],
			'ks': [ 'ks-arab' ],
			'ksh': [ 'de' ],
			'ksw': [ 'my' ],
			'ku': [ 'ku-latn' ],
			'kum': [ 'ru' ],
			'ku-arab': [ 'ckb' ],
			'kv': [ 'ru' ],
			'lad': [ 'es' ],
			'lb': [ 'de' ],
			'lbe': [ 'ru' ],
			'lez': [ 'ru', 'az' ],
			'li': [ 'nl' ],
			'lij': [ 'it' ],
			'liv': [ 'et' ],
			'lki': [ 'fa' ],
			'lld': [ 'it', 'rm', 'fur' ],
			'lmo': [ 'pms', 'eml', 'lij', 'vec', 'it' ],
			'ln': [ 'fr' ],
			'lrc': [ 'fa' ],
			'ltg': [ 'lv' ],
			'luz': [ 'fa' ],
			'lzh': [ 'zh-hant', 'zh', 'zh-hans' ],
			'lzz': [ 'tr' ],
			'mad': [ 'id' ],
			'mai': [ 'hi' ],
			'map-bms': [ 'jv', 'id' ],
			'mdf': [ 'myv', 'ru' ],
			'mg': [ 'fr' ],
			'mhr': [ 'mrj', 'ru' ],
			'min': [ 'id' ],
			'mnw': [ 'my' ],
			'mo': [ 'ro' ],
			'mrj': [ 'mhr', 'ru' ],
			'ms-arab': [ 'ms' ],
			'mwl': [ 'pt' ],
			'myv': [ 'mdf', 'ru' ],
			'mzn': [ 'fa' ],
			'nah': [ 'es' ],
			'nan': [ 'cdo', 'zh-hant', 'zh', 'zh-hans' ],
			'nap': [ 'it' ],
			'nb': [ 'nn' ],
			'nds': [ 'de' ],
			'nds-nl': [ 'nl' ],
			'nia': [ 'id' ],
			'nl-informal': [ 'nl' ],
			'nn': [ 'nb' ],
			'nrm': [ 'nrf', 'fr' ],
			'oc': [ 'ca', 'fr' ],
			'olo': [ 'fi' ],
			'os': [ 'ru' ],
			'pcd': [ 'fr' ],
			'pdc': [ 'de' ],
			'pdt': [ 'de' ],
			'pfl': [ 'de' ],
			'pih': [ 'en' ],
			'pms': [ 'it' ],
			'pnt': [ 'el' ],
			'pt': [ 'pt-br' ],
			'pt-br': [ 'pt' ],
			'pwn': [ 'zh-tw', 'zh-hant', 'zh', 'zh-hans' ],
			'qu': [ 'qug', 'es' ],
			'qug': [ 'qu', 'es' ],
			'rgn': [ 'it' ],
			'rmy': [ 'ro' ],
			'roa-tara': [ 'it' ],
			'rsk': [ 'sr-ec' ],
			'rue': [ 'uk', 'ru' ],
			'rup': [ 'ro' ],
			'ruq': [ 'ruq-latn', 'ro' ],
			'ruq-cyrl': [ 'mk' ],
			'ruq-latn': [ 'ro' ],
			'sa': [ 'hi' ],
			'sah': [ 'ru' ],
			'scn': [ 'it' ],
			'sco': [ 'en' ],
			'sdc': [ 'it' ],
			'sdh': [ 'cbk', 'fa' ],
			'se': [ 'nb', 'fi' ],
			'ses': [ 'fr' ],
			'se-fi': [ 'se', 'fi', 'sv' ],
			'se-no': [ 'se', 'nb', 'nn' ],
			'se-se': [ 'se', 'sv' ],
			'sg': [ 'fr' ],
			'sgs': [ 'lt' ],
			'sh': [ 'bs', 'sr-el', 'hr' ],
			'shi': [ 'fr' ],
			'shy': [ 'shy-latn' ],
			'shy-latn': [ 'fr' ],
			'sjd': [ 'ru' ],
			'sk': [ 'cs' ],
			'skr': [ 'skr-arab' ],
			'skr-arab': [ 'ur', 'pnb' ],
			'sli': [ 'de' ],
			'smn': [ 'fi' ],
			'sr': [ 'sr-ec' ],
			'srn': [ 'nl' ],
			'stq': [ 'de' ],
			'sty': [ 'ru' ],
			'su': [ 'id' ],
			'szl': [ 'pl' ],
			'szy': [ 'zh-tw', 'zh-hant', 'zh', 'zh-hans' ],
			'tay': [ 'zh-tw', 'zh-hant', 'zh', 'zh-hans' ],
			'tcy': [ 'kn' ],
			'tet': [ 'pt' ],
			'tg': [ 'tg-cyrl' ],
			'trv': [ 'zh-tw', 'zh-hant', 'zh', 'zh-hans' ],
			'tt': [ 'tt-cyrl', 'ru' ],
			'tt-cyrl': [ 'ru' ],
			'ty': [ 'fr' ],
			'tyv': [ 'ru' ],
			'udm': [ 'ru' ],
			'ug': [ 'ug-arab' ],
			'vec': [ 'it' ],
			'vep': [ 'et' ],
			'vls': [ 'nl' ],
			'vmf': [ 'de' ],
			'vmw': [ 'pt' ],
			'vot': [ 'fi' ],
			'vro': [ 'et' ],
			'wa': [ 'fr' ],
			'wls': [ 'fr' ],
			'wo': [ 'fr' ],
			'wuu': [ 'zh-hans', 'zh', 'zh-hant' ],
			'xal': [ 'ru' ],
			'xmf': [ 'ka' ],
			'yi': [ 'he' ],
			'yue': [ 'zh-hk', 'zh-hant', 'zh', 'zh-hans' ],
			'za': [ 'zh-hans', 'zh', 'zh-hant' ],
			'zea': [ 'nl' ],
			'zgh': [ 'kab' ],
			'zh': [ 'zh-hans', 'zh-hant', 'zh-cn', 'zh-tw', 'zh-hk' ],
			'zh-cn': [ 'zh-hans', 'zh', 'zh-hant' ],
			'zh-hans': [ 'zh-cn', 'zh', 'zh-hant' ],
			'zh-hant': [ 'zh-tw', 'zh-hk', 'zh', 'zh-hans' ],
			'zh-hk': [ 'zh-hant', 'zh-tw', 'zh', 'zh-hans' ],
			'zh-mo': [ 'zh-hk', 'zh-hant', 'zh-tw', 'zh', 'zh-hans' ],
			'zh-my': [ 'zh-sg', 'zh-hans', 'zh-cn', 'zh', 'zh-hant' ],
			'zh-sg': [ 'zh-hans', 'zh-cn', 'zh', 'zh-hant' ],
			'zh-tw': [ 'zh-hant', 'zh-hk', 'zh', 'zh-hans' ]
		};

	/*
	 * Get the normalised IETF/BCP 47 language tag.
	 * 
	 * mediawiki.language.bcp47 doesn't handle deprecated language codes, and
	 * some non-standard language codes are missed from LanguageCode.php, so
	 * this function is added to override the behavior.
	 *
	 * @param {string} lang The language code to convert.
	 * @return {string} The language code complying with BCP 47 standards.
	 *
	 * @see https://gerrit.wikimedia.org/r/c/mediawiki/core/+/376506/
	 * @see /resources/src/mediawiki.language/mediawiki.language.js in MediaWiki core
	 * @see /includes/language/LanguageCode.php in MediaWiki core
	 */
	function bcp47( lang ) {
		if ( nonStandardCodes[ lang ] ) {
			return nonStandardCodes[ lang ];
		}

		if ( deprecatedCodes[ lang ] ) {
			return bcp47( deprecatedCodes[ lang ] );
		}

		/*
		 * @var {string[]} formatted
		 * @var {boolean} isFirstSegment Whether is the first segment
		 * @var {boolean} isPrivate Whether the code of the segment is private use
		 * @var {string[]} segments The segments of language code
		 */
		var formatted,
			isFirstSegment = true,
			isPrivate = false,
			segments = lang.split( '-' );

		formatted = segments.map( function ( segment ) {
			/*
			 * @var {string} newSegment The converted segment of language code
			 */
			var newSegment;

			/* when previous segment is x, it is a private segment and should be lc */
			if ( isPrivate ) {
				newSegment = segment.toLowerCase();
			/* ISO 3166 country code */
			} else if ( segment.length === 2 && !isFirstSegment ) {
				newSegment = segment.toUpperCase();
			/* ISO 15924 script code */
			} else if ( segment.length === 4 && !isFirstSegment ) {
				newSegment = segment.charAt( 0 ).toUpperCase() + segment.substring( 1 ).toLowerCase();
			/* Use lowercase for other cases */
			} else {
				newSegment = segment.toLowerCase();
			}

			isPrivate = segment.toLowerCase() === 'x';
			isFirstSegment = false;

			return newSegment;
		} );

		return formatted.join( '-' );
	}

	/*
	 * Log a warning message to the browser console if the language fallback chain is
	 * about to start a loop. Only logs once to prevent flooding the browser console.
	 *
	 * @param {string} lang Language in use when loop was found.
	 * @param {string[]} fallbackChain Array of languages involved in the loop.
	 */
	function warnOnFallbackLoop( lang, fallbackChain ) {
		if ( warnedAboutFallbackLoop ) {
			return;
		}
		warnedAboutFallbackLoop = true;

		fallbackChain.push( lang );
		console.error( '[I18n-js] Duplicated fallback language found. Please leave a message at <https://dev.fandom.com/wiki/Talk:I18n-js> and include the following line: \nLanguage fallback chain:', fallbackChain.join( ', ' ) );
	}

	/*
	 * Get a translation of a message from the messages object in the
	 * requested language.
	 *
	 * @param {object} messages The message object to look translations up in.
	 * @param {string} msgName The name of the message to get.
	 * @param {string} lang The language to get the message in.
	 * @param {string[]} fallbackChain Array of languages that have already been checked.
	 *	 Used to detect if the fallback chain is looping.
	 * @return {(string|boolean)} The requested translation or `false` if no message could be found.
	 */
	function getMsg( messages, msgName, lang, fallbackChain ) {
		if ( deprecatedCodes[ lang ] ) {
			return getMsg( messages, msgName, deprecatedCodes[ lang ], fallbackChain );
		}

		if ( messages[ lang ] && messages[ lang ][ msgName ] ) {
			return messages[ lang ][ msgName ];
		}

		if ( !fallbackChain ) {
			fallbackChain = [];
		}

		/*
		 * @var {string} fallbackLang
		 */
		for ( var fallbackLang of fallbacks[ lang ] ) {
			if ( messages[ fallbackLang ] && messages[ fallbackLang ][ msgName ] ) {
				return messages[ fallbackLang ][ msgName ];
			}

			if ( fallbackChain.indexOf( fallbackLang ) !== -1 ) {
				/*
				 * Duplicated language code in fallback list
				 * Try to find next fallback language from list
				 */
				warnOnFallbackLoop( fallbackLang, fallbackChain );
				continue;
			}
			fallbackChain.push( fallbackLang );
		}

		/* No more languages in fallback list - switch to English */
		if ( messages.en && messages.en[ msgName ] ) {
			return messages.en[ msgName ];
		}

		return false;
	}

	/*
	 * Substitute arguments into the string, where arguments are represented
	 * as $n where n > 0.
	 *
	 * @param {string} message The message to substitute arguments into
	 * @param {array} arguments The arguments to substitute in.
	 * @return {string} The resulting message.
	 */
	function handleArgs( message, args ) {
		args.forEach( function ( elem, index ) {
			/*
			 * @var {RegExp} rgx
			 */
			var rgx = new RegExp( '\\$' + ( index + 1 ), 'g' );
			message = message.replace( rgx, elem );
		} );

		return message;
	}

	/*
	 * Generate a HTML link using the supplied parameters.
	 *
	 * @param {string} href The href of the link which will be converted to
	 *	 '/wiki/href'.
	 * @param {string} text The text and title of the link. If this is not supplied, it
	 *	 will default to href.
	 * @param {boolean} hasProtocol True if the href parameter already includes the
	 *	 protocol (i.e. it begins with 'http://', 'https://', or '//').
	 * @return {string} The generated link.
	 */
	function makeLink( href, text, hasProtocol ) {
		text = text || href;
		href = hasProtocol ? href : mw.util.getUrl( href );

		text = mw.html.escape( text );
		href = mw.html.escape( href );

		return '<a href="' + href + '" title="' + text + '">' + text + '</a>';
	}

	/*
	 * Allow basic inline HTML tags in wikitext.does not support <a> as that's handled by the
	 * wikitext links instead.
	 *
	 * Supports the following tags:
	 * - <i>
	 * - <b>
	 * - <s>
	 * - <br>
	 * - <em>
	 * - <strong>
	 * - <span>
	 *
	 * Supports the following tag attributes:
	 * - title
	 * - style
	 * - class
	 *
	 * @param html
	 * @return The sanitised HTML code.
	 */
	function sanitiseHtml( html ) {
		/*
		 * @var context
		 */
		var context = document.implementation.createHTMLDocument( '' ),
			$html = $.parseHTML( html, /* document */ context, /* keepscripts */ false ),
			$div = $( '<div>', context ).append( $html ),
			allowedAttrs = [
				'title',
				'style',
				'class'
			],
			allowedTags = [
				'i',
				'b',
				's',
				'br',
				'em',
				'strong',
				'span',
			];

		$div.find( '*' ).each( function () {
			var $this = $( this ),
				tagname = $this.prop( 'tagName' ).toLowerCase(),
				attrs,
				array,
				style;

			if ( allowedTags.indexOf( tagname ) === -1 ) {
				mw.log( '[I18n-js] Disallowed tag in message: ' + tagname );
				$this.remove();
				return;
			}

			attrs = $this.prop( 'attributes' );
			array = Array.prototype.slice.call( attrs );

			array.forEach( function ( attr ) {
				if ( allowedAttrs.indexOf( attr.name ) === -1 ) {
					mw.log( '[I18n-js] Disallowed attribute in message: ' + attr.name + ', tag: ' + tagname );
					$this.removeAttr( attr.name );
					return;
				}

				/* Make sure there's nothing nasty in style attributes */
				if ( attr.name === 'style' ) {
					style = $this.attr( 'style' );

					if ( style.indexOf( 'url(' ) > -1 ) {
						mw.log( '[I18n-js] Disallowed url() in style attribute' );
						$this.removeAttr( 'style' );

					/* https://phabricator.wikimedia.org/T208881 */
					} else if ( style.indexOf( 'var(' ) > -1 ) {
						mw.log( '[I18n-js] Disallowed var() in style attribute' );
						$this.removeAttr( 'style' );
					}
				}
			} );
		} );

		return $div.prop( 'innerHTML' );
	}

	/*
	 * Parse some basic wikitext into HTML. Also supports basic inline HTML tags.
	 *
	 * Will process:
	 * - [url text]
	 * - [[pagename]]
	 * - [[pagename|text]]
	 * - {{PLURAL:count|singular|plural}}
	 * - {{GENDER:gender|masculine|feminine|neutral}}
	 *
	 * @param {string} message The message to process.
	 * @return {string} The resulting string.
	 */
	function parse( message ) {
		/* [url text] -> [$1 $2] */
		var urlRgx = /\[((?:https?:)?\/\/.+?) (.+?)\]/g,
			/* [[pagename]] -> [[$1]] */
			simplePageRgx = /\[\[([^|]*?)\]\]/g,
			/* [[pagename|text]] -> [[$1|$2]] */
			pageWithTextRgx = /\[\[(.+?)\|(.+?)\]\]/g,
			/* {{PLURAL:count|singular|plural}} -> {{PLURAL:$1|$2}} */
			pluralRgx = /\{\{PLURAL:(\d+)\|(.+?)\}\}/gi,
			/* {{GENDER:gender|masculine|feminine|neutral}} -> {{GENDER:$1|$2}} */
			genderRgx = /\{\{GENDER:([^|]+)\|(.+?)\}\}/gi;

		if ( message.indexOf( '<' ) > -1 ) {
			message = sanitiseHtml( message );
		}

		return message
			.replace( urlRgx, function ( _match, href, text ) {
				return makeLink( href, text, true );
			} )
			.replace( simplePageRgx, function ( _match, href ) {
				return makeLink( href );
			} )
			.replace( pageWithTextRgx, function ( _match, href, text ) {
				return makeLink( href, text );
			} )
			.replace( pluralRgx, function ( _match, count, forms ) {
				return mw.language.convertPlural( Number( count ), forms.split( '|' ) );
			} )
			.replace(genderRgx, function ( _match, gender, forms ) {
				return mw.language.gender( gender, forms.split( '|' ) );
			} );
	}

	/*
	 * Create a new Message instance.
	 *
	 * @param {object} messages The message object to look translations up in.
	 * @param {string} lang The language to get the message in.
	 * @param {array} args Any arguments to substitute into the message, [0] is message name.
	 * @param {string} name The name of the script the messages are for.
	 * @return
	 */
	function message( messages, lang, args, name ) {
		if ( !args.length ) {
			return;
		}

		/*
		 * @var msgName
		 * @var {string} descriptiveMsgName
		 * @var {object} msg
		 * @var {boolean} msgExists
		 */
		var msgName = args.shift(),
			descriptiveMsgName = 'i18njs-' + name + '-' + msgName,
			msg = getMsg( messages, msgName, lang ),
			msgExists = msg !== false;

		if ( !msgExists ) {
			/* use name wrapped in < > for missing message, per MediaWiki convention */
			msg = '<' + descriptiveMsgName + '>';
		}

		if ( conf.wgUserLanguage === 'qqx' && msgExists ) {
			/* https://www.mediawiki.org/wiki/Help:System_message#Finding_messages_and_documentation */
			msg = '(' + descriptiveMsgName + ')';
		} else if ( overrides[ name ] && overrides[ name ][ msgName ] ) {
			/* if the message has been overridden, use that without checking the language */
			msg = overrides[ name ][ msgName ];
			msgExists = true;
		}

		if ( args.length ) {
			msg = handleArgs( msg, args );
		}

		return {
			/*
			 * @return {boolean} Representing whether the message exists.
			 */
			exists: msgExists,

			/*
			 * Parse wikitext links in the message and return the result.
			 *
			 * @return {string} The resulting string.
			 */
			parse: function () {
				/*
				 * Skip parsing if the message wasn't found; otherwise
				 * the sanitisation will mess with it.
				 */
				if ( !this.exists ) {
					return this.escape();
				}

				return parse( msg );
			},

			/*
			 * Escape any HTML in the message and return the result.
			 *
			 * @return {string} The resulting string.
			 */
			escape: function () {
				return mw.html.escape( msg );
			},

			/*
			 * Return the message as is.
			 *
			 * @return {string} The resulting string.
			 */
			plain: function () {
				return msg;
			}
		};
	}

	/*
	 * Create a new i18n object.
	 *
	 * @param {object} messages The message object to look translations up in.
	 * @param {string} name The name of the script the messages are for.
	 * @param {object} options Options set by the loading script.
	 * @return {object}
	 */
	function i18n( messages, name, options ) {
		var defaultLang = options.language,
			tempLang = null;

		return {
			/*
			 * Set the default language.
			 *
			 * @deprecated since v0.6 (2020-08-25), no longer supported.
			 */
			useLang: function () {
				console.warn( '[I18n-js] “useLang()” is no longer supported by I18n-js (used in “' + name + '”) - using user language.' );
				this.useUserLang();
			},

			/*
			 * Set the language for the next msg call.
			 *
			 * @param {string} lang The language code to use for the next `msg` call.
			 *
			 * @return {object} The current object for use in chaining.
			 */
			inLang: function (lang) {
				if ( !options.cacheAll ) {
					console.warn( '[I18n-js] “inLang()” is not supported without configuring `options.cacheAll` (used in “' + name + '”) - using user language.' );
					lang = options.language;
				}
				tempLang = lang;
				return this;
			},

			/*
			 * Set the default language to the content language.
			 */
			useContentLang: function () {
				defaultLang = conf.wgContentLanguage;
			},

			/*
			 * Set the language for the next `msg` call to the content language.
			 *
			 * @return {object} The current object for use in chaining.
			 */
			inContentLang: function () {
				tempLang = conf.wgContentLanguage;
				return this;
			},

			/*
			 * Set the default language to the page language.
			 */
			usePageLang: function () {
				defaultLang = conf.wgPageContentLanguage;
			},

			/*
			 * Set the language for the next `msg` call to the page language.
			 *
			 * @return {object} The current object for use in chaining.
			 */
			inPageLang: function () {
				tempLang = conf.wgPageContentLanguage;
				return this;
			},

			/*
			 * Set the default language to the page view language.
			 * This is also known as the user language variant.
			 */
			usePageViewLang: function () {
				defaultLang = conf.wgUserVariant || conf.wgContentLanguage;
			},

			/*
			 * Set the language for the next `msg` call to the page view language.
			 * This is also known as the user language variant.
			 *
			 * @return {object} The current object for use in chaining.
			 */
			inPageViewLang: function () {
				tempLang = conf.wgUserVariant || conf.wgContentLanguage;
				return this;
			},

			/*
			 * Set the default language to the user's language.
			 */
			useUserLang: function () {
				defaultLang = options.language;
			},

			/*
			 * Set the language for the next msg call to the user's language.
			 *
			 * @return {object} The current object for use in chaining.
			 */
			inUserLang: function () {
				tempLang = options.language;
				return this;
			},

			/*
			 * Create a new instance of Message.
			 *
			 * @return {object}
			 */
			msg: function () {
				var args = Array.prototype.slice.call( arguments ),
					lang = defaultLang;

				if ( tempLang !== null ) {
					lang = tempLang;
					tempLang = null;
				}

				return message( messages, lang, args, name );
			},

			/*
			 * For accessing the raw messages.
			 * Scripts should not rely on it or any of its properties existing.
			 */
			_messages: messages
		};
	}

	/*
	 * Preprocess each message's fallback chain for the user and content languages.
	 * This allows us to save only those messages needed to the cache.
	 *
	 * @param {string} name The name of the script the messages are for.
	 * @param {object} messages The message object to look translations up in.
	 * @param {object} options Options set by the loading script.
	 */
	function optimiseMessages( name, messages, options ) {
		var existingLangs = cache[ name ] && cache[ name ]._messages._isOptimised,
			langs = [ options.language ],
			msgKeys = Object.keys( messages.en || {} ),
			optimised = {};

		if ( !msgKeys.length ) {
			/* No English messages, don't bother optimising */
			return messages;
		}

		/*
		 * @var addMsgsForLanguage
		 */
		var addMsgsForLanguage = function (lang) {
			if ( optimised[ lang ] ) {
				/* Language already exists */
				return;
			}

			optimised[ lang ] = {};

			msgKeys.forEach( function ( msgName ) {
				/*
				 * @var msg
				 */
				var msg = getMsg( messages, msgName, lang );

				if ( msg !== false ) {
					optimised[ lang ][ msgName ] = msg;
				}
			} );
		};

		if ( langs.indexOf( conf.wgContentLanguage ) === -1 ) {
			langs.push( conf.wgContentLanguage );
		}

		/*
		 * If cache exists and is optimised, preserve existing languages.
		 * This allows an optimised cache even when using different
		 * language wikis on same domain (i.e. sharing same cache).
		 */
		if ( existingLangs ) {
			existingLangs.forEach( function ( lang ) {
				if ( langs.indexOf( lang ) === -1 ) {
					langs.push( lang );
				}
			} );
		}

		langs.forEach( addMsgsForLanguage );

		/*
		 * `cacheAll` is an array of message names for which translations
		 * should not be optimised - save all translations of these messages
		 */
		if ( Array.isArray( options.cacheAll ) ) {
			msgKeys = options.cacheAll;
			Object.keys( messages ).forEach( addMsgsForLanguage );
		}

		optimised._isOptimised = langs;

		return optimised;
	}

	/*
	 * Check that the cache for a script exists and, if optimised, contains the necessary languages.
	 *
	 * @param {string} name The name of the script to check for.
	 * @param {object} options Options set by the loading script.
	 * @return {boolean} Whether the cache should be used.
	 */
	function cacheIsSuitable( name, options ) {
		var messages = cache[ name ] && cache[ name ]._messages;

		/* Nothing in cache */
		if ( !messages ) {
			return false;
		}

		/*
		 * Optimised messages missing user or content language.
		 * We'll need to load from server in this case.
		 */
		if (
			messages._isOptimised &&
			!( messages[ options.language ] && messages[ conf.wgContentLanguage ] )
		) {
			return false;
		}

		return true;
	}

	/*
	 * Remove out-of-date entries in the i18n cache (those older than two days).
	 *
	 * This can never be perfect: it will only work on wikis that are visited.
	 */
	function removeOldCacheEntries() {
		var isCacheKey = new RegExp( '^(' + cachePrefix + '.+)-content$' ),
			storageKeys = [];

		try {
			storageKeys = Object.keys( localStorage );
		} catch ( e ) {}

		storageKeys.filter( function ( key ) {
			return isCacheKey.test( key );
		} ).forEach( function ( key ) {
			var keyPrefix = key.match( isCacheKey )[ 1 ],
				cacheTimestamp;

			try {
				cacheTimestamp = Number( localStorage.getItem( keyPrefix + '-timestamp' ) );
			} catch ( e ) {}

			if ( now - cacheTimestamp < oneDay * 2 ) {
				/* Cached within last two days, keep it */
				return;
			}

			try {
				localStorage.removeItem( keyPrefix + '-content' );
				localStorage.removeItem( keyPrefix + '-timestamp' );
				localStorage.removeItem( keyPrefix + '-version' );
			} catch ( e ) {}
		} );
	}

	/*
	 * Strip block comments from a JSON string which are illegal under the JSON spec.
	 * This is a bit basic, so will remove comments inside strings too.
	 *
	 * @param {string} json The JSON string.
	 * @return {string} The JSON string after any comments have been removed.
	 */
	function stripComments( json ) {
		json = json
			.trim()
			.replace( /\/\*[\s\S]*?\*\//g, '' );
		return json;
	}

	/*
	 * Save messages string to local storage for caching.
	 *
	 * @param {string} name The name of the script the messages are for.
	 * @param {object} json The JSON object.
	 * @param {number} cacheVersion Cache version requested by the loading script.
	 */
	function saveToCache( name, json, cacheVersion ) {
		/*
		 * @var {string} keyPrefix
		 */
		var keyPrefix = cachePrefix + name;

		/* Don't cache empty JSON */
		if ( Object.keys( json ).length === 0 ) {
			return;
		}

		try {
			localStorage.setItem( keyPrefix + '-content', JSON.stringify( json ) );
			localStorage.setItem( keyPrefix + '-timestamp', now );
			localStorage.setItem( keyPrefix + '-version', cacheVersion || 0 );
		} catch ( e ) {}
	}

	/*
	 * Parse JSON string loaded from page and create an i18n object.
	 *
	 * @param {string} name The name of the script the messages are for.
	 * @param {string} res The JSON string.
	 * @param {object} options Options set by the loading script.
	 * @return {object} The resulting i18n object.
	 */
	function parseMessagesToObject( name, res, options ) {
		var json = {},
			obj,
			msg;

		/* Handle parse errors gracefully */
		try {
			res = stripComments( res );
			json = JSON.parse( res );
		} catch ( e ) {
			msg = e.message;

			if ( msg === 'Unexpected end of JSON input' ) {
				msg += '. This may be caused by a non-existent i18n.json page.';
			}

			console.warn( '[I18n-js] SyntaxError in messages: ' + msg );
		}

		if (
			options.useCache &&
			!options.loadedFromCache &&
			options.cacheAll !== true
		) {
			json = optimiseMessages( name, json, options );
		}

		obj = i18n( json, name, options );

		/* Cache the result in case it's used multiple times */
		cache[ name ] = obj;

		if ( !options.loadedFromCache ) {
			saveToCache( name, json, options.cacheVersion );
		}

		return obj;
	}

	/*
	 * Load messages string from local storage cache and add to cache object.
	 *
	 * @param {string} name The name of the script the messages are for.
	 * @param {object} options Options set by the loading script.
	 */
	function loadFromCache( name, options ) {
		var keyPrefix = cachePrefix + name,
			cacheContent,
			cacheVersion;

		try {
			cacheContent = localStorage.getItem( keyPrefix + '-content' );
			cacheVersion = Number( localStorage.getItem( keyPrefix + '-version' ) );
		} catch ( e ) {}

		/* Cache exists, and its version is greater than or equal to requested version */
		if ( cacheContent && cacheVersion >= options.cacheVersion ) {
			options.loadedFromCache = true;
			parseMessagesToObject( name, cacheContent, options );
		}
	}

	/*
	 * Load messages stored as JSON on a page.
	 *
	 * @param {string} name The name of the script the messages are for. This will be
	 *	 used to get messages from
	 *	 https://dev.fandom.com/wiki/MediaWiki:Custom-name/i18n.json.
	 *   Use `u:<subdomain>` or `u:<language-path>.<subdomain>` to set other Fandom
	 *   wikis as the source.
	 * @param {object} options Options set by the loading script:
	 * - {string} apiEndpoint: Use `u:<subdomain>` or `u:<language-path>.<subdomain>`
	 *     to set other sites as the API endpoint of the source. Currently only
	 *     support Fandom wikis.
	 * - {string} page: Set other format of the full page name for the i18n JSON.
	 *     Use $1 for the placeholder of name.
	 * - {(array|boolean)} cacheAll: Either an array of message names for which translations should not be optimised,
	 *     or `true` to disable the optimised cache.
	 * - {number} cacheVersion: Minimum cache version requested by the loading script.
	 * - {string} language: Set a default language for the script to use, instead of wgUserLanguage.
	 * - noCache: Never load i18n from cache (not recommended for general use).
	 *
	 * @return {object} A jQuery.Deferred instance.
	 */
	function loadMessages( name, options ) {
		/*
		 * @var {object} deferred
		 * @var {string} apiEndpoint
		 * @var {RegExp} apiEndpointRgx
		 * @var {string} page
		 * @var {object} params
		 */
		var deferred = $.Deferred(),
			customSource = name.match( /^u:(?:([a-z-]+)\.)?([a-z0-9-]+):/ ),
			apiEndpoint = 'https://dev.fandom.com/api.php',
			apiEndpointRgx = new RegExp(
				/* '^(https:\/\/(([a-z0-9-]+)\.fandom\.com(?:\/([a-z-]+))?|(([a-z-]+)\.wikipedia\.org\/w))\/api\.php)$' */
				'^(https:\/\/(([a-z0-9-]+)\.fandom\.com(?:\/([a-z-]+))?)\/api\.php)$'
			),
			page = 'MediaWiki:Custom-' + name + '/i18n.json',
			params;

		options = options || {};
		if ( options.apiEndpoint && apiEndpointRgx.test( options.apiEndpoint ) ) {
			options.apiEndpoint = options.apiEndpoint;
		} else {
			options.apiEndpoint = apiEndpoint;
		}
		options.page = ( options.page && options.page.replace( /\$1/g, name ) ) || page;
		options.cacheVersion = Number( options.cacheVersion ) || 0;
		options.language = options.language || conf.wgUserLanguage;
		options.useCache = ( options.noCache || conf.debug ) !== true;

		if ( options.useCache ) {
			loadFromCache( name, options );

			if ( cacheIsSuitable( name, options ) ) {
				return deferred.resolve( cache[ name ] );
			}
		}

		/* Cache isn't suitable - loading from server */
		options.loadedFromCache = false;

		/*
		 * Allow custom i18n pages to be specified on other wikis.
		 * Mainly for SOAP Wiki to keep their own JSON file.
		 * Note this only supports loading from wikis on fandom.com.
		 */
		if ( customSource ) {
			apiEndpoint = apiEndpoint.replace( 'dev', customSource[ 2 ] );
			page = name.slice( customSource[ 0 ].length );

			// adjust endpoint when loading from interlanguage wiki
			if ( customSource[ 1 ] ) {
				apiEndpoint = apiEndpoint.replace(
					/api\.php$/,
					customSource[ 1 ] + '/$&'
				);
			}
		}

		params = {
			action: 'query',
			format: 'json',
			prop: 'revisions',
			rvprop: 'content',
			titles: page,
			indexpageids: 1,
			origin: '*',
			// Cache results for 5 minutes in CDN and browser
			maxage: 300,
			smaxage: 300
		};

		/*
		 * 'site' and 'user' are dependencies so end-users can set overrides in their local JS
		 * and have it take effect before we load the messages.
		 * Generally, we will implicitly depend on those anyway due to where/when this is loaded.
		 */
		mw.loader.using( [ 'mediawiki.language', 'mediawiki.util'/*, 'site', 'user'*/ ], function () {
			$.ajax( apiEndpoint, {
				data: params,
			} ).always( function ( data ) {
				var res = '',
					revisionData = data.query && data.query.pages[ data.query.pageids[ 0 ] ].revisions;

				if ( revisionData ) {
					res = revisionData[ 0 ][ '*' ];
				}

				deferred.resolve( parseMessagesToObject( name, res, options ) );
			} );
		} );

		return deferred;
	}

	/* Expose under the dev global */
	window.dev.i18n = $.extend( window.dev.i18n, {
		loadMessages: loadMessages,

		/*
		 * "Hidden" functions to allow testing and debugging
		 * they may be changed or removed without warning.
		 * Scripts should not rely on these existing or their output being in any particular format.
		 */
		_bcp47: bcp47,
		_stripComments: stripComments,
		_saveToCache: saveToCache,
		_getMsg: getMsg,
		_handleArgs: handleArgs,
		_parse: parse,
		_fallbacks: fallbacks,
		_cache: cache
	} );

	/* Initialise overrides object */
	window.dev.i18n.overrides = window.dev.i18n.overrides || {};
	overrides = window.dev.i18n.overrides;

	/*
	 * Fire an event on load
	 *
	 * Alternatively, use $.getScript (or mw.loader)
	 * and use the returned promise
	 */
	mw.hook( 'dev.i18n' ).fire( window.dev.i18n );

	/* tidy the localStorage cache of old entries */
	removeOldCacheEntries();

} ( this, jQuery, mediaWiki ) );