wikimedia/mediawiki-extensions-Wikibase

/**
 * @license GPL-2.0-or-later
 */
( function ( wb ) {
    'use strict';

    var termLanguages = require( './termLanguages.json' );

    function filterInvalidTermsLanguages( languages ) {
        return languages.filter( function ( language ) {
            return termLanguages.indexOf( language ) !== -1;
        } );
    }

    /**
     * @return {string[]} An ordered list of languages the user wants to use, the first being her
     * preferred language, and thus the UI language (currently wgUserLanguage).
     */
    wb.getUserLanguages = function () {
        var userLanguage = mw.config.get( 'wgUserLanguage' ),
            userSpecifiedLanguages = mw.config.get(
                'wbUserSpecifiedLanguages', [] ),
            userPreferredContentLanguages = mw.config.get(
                'wbUserPreferredContentLanguages', userSpecifiedLanguages );

        // start with the preferred languages as determined by the server
        var languages = userPreferredContentLanguages.slice();

        // if the user did not specify any languages (e.g. in Babel),
        // then the preferred languages are not as useful,
        // so add up to four suggestions from ULS
        if ( !userSpecifiedLanguages.length && mw.uls && $.uls && $.uls.data ) {
            var frequentLanguages = mw.uls.getFrequentLanguageList();
            for ( var i = 0; i < 4 && i < frequentLanguages.length; i++ ) {
                if ( languages.indexOf( frequentLanguages[ i ] ) === -1 ) {
                    languages.push( frequentLanguages[ i ] );
                }
            }
        }

        // throw out any invalid languages
        languages = filterInvalidTermsLanguages( languages );

        // ensure the list starts with the UI language
        // (unclear if this is intentionally or accidentally after filterInvalidTermsLanguages())
        var userLanguageIndex = languages.indexOf( userLanguage );
        if ( userLanguageIndex !== -1 ) {
            languages.splice( userLanguageIndex, 1 );
        }
        languages.unshift( userLanguage );

        return languages;
    };
}( wikibase ) );