[FIX] Login change language button (#16085)

app/ui-login/client/login/footer.js

@@ -5,24 +5,44 @@ import { TAPi18n } from 'meteor/rocketchat:tap-i18n';
 
 import { settings } from '../../../settings';
 
-Template.loginFooter.onCreated(function() {
-	this.suggestedLanguage = new ReactiveVar();
+const filterLanguage = (language) => {
+	// Fix browsers having all-lowercase language settings eg. pt-br, en-us
+	const regex = /([a-z]{2,3})-([a-z]{2,4})/;
+	const matches = regex.exec(language);
+	if (matches) {
+		return `${ matches[1] }-${ matches[2].toUpperCase() }`;
+	}
 
-	this.suggestAnotherLanguageFor = (language) => {
-		const loadAndSetSuggestedLanguage = (language) => TAPi18n._loadLanguage(language)
-			.then(() => this.suggestedLanguage.set(language));
+	return language;
+};
 
-		const serverLanguage = settings.get('Language');
+Template.loginFooter.onCreated(function() {
+	this.suggestedLanguage = new ReactiveVar();
 
-		if (serverLanguage !== language) {
-			loadAndSetSuggestedLanguage(serverLanguage || 'en');
-		} else if (!/^en/.test(language)) {
-			loadAndSetSuggestedLanguage('en');
-		} else {
-			this.suggestedLanguage.set(undefined);
+	const loadAndSetSuggestedLanguage = async (language = 'en') => {
+		const lng = filterLanguage(language);
+		try {
+			await TAPi18n._loadLanguage(filterLanguage(lng));
+			window.setLanguage(lng);
+
+			const serverLanguage = filterLanguage(settings.get('Language'));
+
+			if (serverLanguage !== lng) {
+				return serverLanguage;
+			}
+			if (serverLanguage !== 'en') {
+				return 'en';
+			}
+		} catch (e) {
+			return null;
 		}
 	};
 
+	this.suggestAnotherLanguageFor = async (language) => {
+		const suggest = await loadAndSetSuggestedLanguage(language);
+		this.suggestedLanguage.set(suggest);
+	};
+
 	const currentLanguage = Meteor._localStorage.getItem('userLanguage');
 	this.suggestAnotherLanguageFor(currentLanguage);
 });
@@ -37,7 +57,6 @@ Template.loginFooter.helpers({
 Template.loginFooter.events({
 	'click button.js-switch-language'(e, t) {
 		const language = t.suggestedLanguage.get();
-		window.setLanguage(language);
 		t.suggestAnotherLanguageFor(language);
 		return false;
 	},