feat: Add new isRTL function

lib/index.ts

@@ -14,5 +14,6 @@ console.warn(n('my-app', 'Got an error', 'Got multiple errors', 2));
 
 export type { Translations } from './registry'
 
-export * from './translation'
 export * from './date'
+export * from './locale'
+export * from './translation'

lib/locale.ts

@@ -0,0 +1,67 @@
+/**
+ * Returns the user's locale
+ */
+export function getLocale(): string {
+	return document.documentElement.dataset.locale || 'en'
+}
+
+/**
+ * Returns user's locale in canonical form
+ * E.g. `en-US` instead of `en_US`
+ */
+export function getCanonicalLocale(): string {
+	return getLocale().replace(/_/g, '-')
+}
+
+/**
+ * Returns the user's language
+ */
+export function getLanguage(): string {
+	return document.documentElement.lang || 'en'
+}
+
+/**
+ * Check whether the current, or a given, language is read right-to-left
+ *
+ * @param language Language code to check, defaults to current language
+ */
+export function isRTL(language?: string): boolean {
+	const languageCode = language || getLanguage()
+
+	// Source: https://meta.wikimedia.org/wiki/Template:List_of_language_names_ordered_by_code
+	const rtlLanguages = [
+		/* eslint-disable no-multi-spaces */
+		'ae',  // Avestan
+		'ar',  // 'العربية', Arabic
+		'arc', // Aramaic
+		'arz', // 'مصرى', Egyptian
+		'bcc', // 'بلوچی مکرانی', Southern Balochi
+		'bqi', // 'بختياري', Bakthiari
+		'ckb', // 'Soranî / کوردی', Sorani
+		'dv',  // Dhivehi
+		'fa',  // 'فارسی', Persian
+		'glk', // 'گیلکی', Gilaki
+		'ha',  // 'هَوُسَ', Hausa
+		'he',  // 'עברית', Hebrew
+		'khw', // 'کھوار', Khowar
+		'ks',  // 'कॉशुर / کٲشُر', Kashmiri
+		'ku',  // 'Kurdî / كوردی', Kurdish
+		'mzn', // 'مازِرونی', Mazanderani
+		'nqo', // 'ߒߞߏ', N’Ko
+		'pnb', // 'پنجابی', Western Punjabi
+		'ps',  // 'پښتو', Pashto,
+		'sd',  // 'سنڌي', Sindhi
+		'ug',  // 'Uyghurche / ئۇيغۇرچە', Uyghur
+		'ur',  // 'اردو', Urdu
+		'uzs', // 'اوزبیکی', Uzbek Afghan
+		'yi',  // 'ייִדיש', Yiddish
+		/* eslint-enable no-multi-spaces */
+	]
+
+	// special case for Uzbek Afghan
+	if ((language || getCanonicalLocale()).startsWith('uz-AF')) {
+		return true
+	}
+
+	return rtlLanguages.includes(languageCode)
+}

lib/translation.ts

@@ -1,10 +1,11 @@
+import type { Translations } from './registry'
+import { getLanguage, getLocale } from './locale'
 import {
 	getAppTranslations,
 	hasAppTranslations,
 	registerAppTranslations,
 	unregisterAppTranslations,
 } from './registry'
-import type { Translations } from './registry'
 import { generateFilePath } from '@nextcloud/router'
 
 import DOMPurify from 'dompurify'
@@ -18,28 +19,6 @@ interface TranslationOptions {
 	sanitize?: boolean
 }
 
-/**
- * Returns the user's locale
- */
-export function getLocale(): string {
-	return document.documentElement.dataset.locale || 'en'
-}
-
-/**
- * Returns user's locale in canonical form
- * E.g. `en-US` instead of `en_US`
- */
-export function getCanonicalLocale(): string {
-	return getLocale().replace(/_/g, '-')
-}
-
-/**
- * Returns the user's language
- */
-export function getLanguage(): string {
-	return document.documentElement.lang || 'en'
-}
-
 /**
  * Translate a string
  *

tests/locale.test.ts

@@ -0,0 +1,92 @@
+import {
+	getCanonicalLocale,
+	getLanguage,
+	getLocale,
+	isRTL
+} from '../lib/locale'
+
+const setLocale = (locale: string) => document.documentElement.setAttribute('data-locale', locale)
+const setLanguage = (lang: string) => document.documentElement.setAttribute('lang', lang)
+
+describe('getCanonicalLocale', () => {
+	afterEach(() => {
+		setLocale('')
+	})
+
+	it('Returns primary locales as is', () => {
+		setLocale('de')
+		expect(getCanonicalLocale()).toEqual('de')
+		setLocale('zu')
+		expect(getCanonicalLocale()).toEqual('zu')
+	})
+
+	it('Returns extended locales with hyphens', () => {
+		setLocale('az_Cyrl_AZ')
+		expect(getCanonicalLocale()).toEqual('az-Cyrl-AZ')
+		setLocale('de_DE')
+		expect(getCanonicalLocale()).toEqual('de-DE')
+	})
+})
+
+test('getLanguage', () => {
+	document.documentElement.removeAttribute('lang')
+	// Expect fallback
+	expect(getLanguage()).toBe('en')
+	setLanguage('')
+	expect(getLanguage()).toBe('en')
+
+	// Expect value
+	setLanguage('zu')
+	expect(getLanguage()).toBe('zu')
+})
+
+test('getLocale', () => {
+	document.documentElement.removeAttribute('data-locale')
+	// Expect fallback
+	expect(getLocale()).toBe('en')
+	setLocale('')
+	expect(getLocale()).toBe('en')
+
+	// Expect value
+	setLocale('de_DE')
+	expect(getLocale()).toBe('de_DE')
+})
+
+describe('isRTL', () => {
+	beforeEach(() => document.documentElement.removeAttribute('data-locale'))
+
+	it('fallsback to English which is LTR', () => {
+		// Expect fallback which is English = LTR
+		expect(isRTL()).toBe(false)
+	})
+
+	it('uses the given argument over the current language', () => {
+		// If a value is given it should use that language over the fallback
+		expect(isRTL('ar')).toBe(true)
+		setLanguage('ar')
+		expect(isRTL('de')).toBe(false)
+	})
+
+	it('without an argument the current language is used', () => {
+		// It uses the configured language
+		setLanguage('he')
+		expect(isRTL()).toBe(true)
+	})
+
+	it('without an argument the current language is used', () => {
+		// It uses the configured language
+		setLanguage('he')
+		expect(isRTL()).toBe(true)
+	})
+
+	it('handles Uzbek Afghan correctly', () => {
+		// Given as argument
+		expect(isRTL('uz')).toBe(false)
+		expect(isRTL('uz-AF')).toBe(true)
+
+		// configured as current language
+		setLanguage('uz')
+		setLocale('uz_AF')
+		expect(isRTL()).toBe(true)
+	})
+})

tests/translation.test.ts

@@ -1,8 +1,5 @@
 import type { NextcloudWindowWithRegistry } from '../lib/registry'
 import {
-	getCanonicalLocale,
-	getLanguage,
-	getLocale,
 	getPlural,
 	register,
 	translate,
@@ -15,50 +12,6 @@ declare const window: NextcloudWindowWithRegistry
 const setLocale = (locale: string) => document.documentElement.setAttribute('data-locale', locale)
 const setLanguage = (lang: string) => document.documentElement.setAttribute('lang', lang)
 
-describe('getCanonicalLocale', () => {
-	afterEach(() => {
-		setLocale('')
-	})
-
-	it('Returns primary locales as is', () => {
-		setLocale('de')
-		expect(getCanonicalLocale()).toEqual('de')
-		setLocale('zu')
-		expect(getCanonicalLocale()).toEqual('zu')
-	})
-
-	it('Returns extended locales with hyphens', () => {
-		setLocale('az_Cyrl_AZ')
-		expect(getCanonicalLocale()).toEqual('az-Cyrl-AZ')
-		setLocale('de_DE')
-		expect(getCanonicalLocale()).toEqual('de-DE')
-	})
-})
-
-test('getLanguage', () => {
-	document.documentElement.removeAttribute('lang')
-	// Expect fallback
-	expect(getLanguage()).toBe('en')
-	setLanguage('')
-	expect(getLanguage()).toBe('en')
-
-	// Expect value
-	setLanguage('zu')
-	expect(getLanguage()).toBe('zu')
-})
-
-test('getLocale', () => {
-	document.documentElement.removeAttribute('data-locale')
-	// Expect fallback
-	expect(getLocale()).toBe('en')
-	setLocale('')
-	expect(getLocale()).toBe('en')
-
-	// Expect value
-	setLocale('de_DE')
-	expect(getLocale()).toBe('de_DE')
-})
-
 describe('translate', () => {
 	const mockWindowDE = () => {
 		window._oc_l10n_registry_translations = {