RTL

app/locale.ts

@@ -5,11 +5,17 @@ import { join } from 'path';
 import { readFileSync } from 'fs';
 import { merge } from 'lodash';
 import * as LocaleMatcher from '@formatjs/intl-localematcher';
+import { z } from 'zod';
 import { setupI18n } from '../ts/util/setupI18n';
 
 import type { LoggerType } from '../ts/types/Logging';
 import type { LocaleMessagesType } from '../ts/types/I18N';
 import type { LocalizerType } from '../ts/types/Util';
+import * as Errors from '../ts/types/errors';
+
+const TextInfoSchema = z.object({
+  direction: z.enum(['ltr', 'rtl']),
+});
 
 function getLocaleMessages(locale: string): LocaleMessagesType {
   const targetFile = join(__dirname, '..', '_locales', locale, 'messages.json');
@@ -17,25 +23,64 @@ function getLocaleMessages(locale: string): LocaleMessagesType {
   return JSON.parse(readFileSync(targetFile, 'utf-8'));
 }
 
+export type LocaleDirection = 'ltr' | 'rtl';
+
 export type LocaleType = {
   i18n: LocalizerType;
   name: string;
+  direction: LocaleDirection;
   messages: LocaleMessagesType;
 };
 
+function getLocaleDirection(
+  localeName: string,
+  logger: LoggerType
+): LocaleDirection {
+  const locale = new Intl.Locale(localeName);
+  // TC39 proposal is now `locale.getTextInfo()` but in browsers its currently
+  // `locale.textInfo`
+  try {
+    // @ts-expect-error -- TS doesn't know about this method
+    if (typeof locale.getTextInfo === 'function') {
+      return TextInfoSchema.parse(
+        // @ts-expect-error -- TS doesn't know about this method
+        locale.getTextInfo()
+      ).direction;
+    }
+    // @ts-expect-error -- TS doesn't know about this property
+    if (typeof locale.textInfo === 'object') {
+      return TextInfoSchema.parse(
+        // @ts-expect-error -- TS doesn't know about this property
+        locale.textInfo
+      ).direction;
+    }
+  } catch (error) {
+    logger.error(
+      'locale: Error getting text info for locale',
+      Errors.toLogFormat(error)
+    );
+  }
+  return 'ltr';
+}
+
 function finalize(
   messages: LocaleMessagesType,
   backupMessages: LocaleMessagesType,
-  localeName: string
+  localeName: string,
+  logger: LoggerType
 ) {
   // We start with english, then overwrite that with anything present in locale
   const finalMessages = merge(backupMessages, messages);
 
   const i18n = setupI18n(localeName, finalMessages);
 
+  const direction = getLocaleDirection(localeName, logger);
+  logger.info(`locale: Text info direction for ${localeName}: ${direction}`);
+
   return {
     i18n,
     name: localeName,
+    direction,
     messages: finalMessages,
   };
 }
@@ -45,17 +90,11 @@ export function load({
   logger,
 }: {
   preferredSystemLocales: Array<string>;
-  logger: Pick<LoggerType, 'warn' | 'info'>;
+  logger: LoggerType;
 }): LocaleType {
   if (preferredSystemLocales == null) {
     throw new TypeError('locale: `preferredSystemLocales` is required');
   }
-  if (!logger.info) {
-    throw new TypeError('locale: `logger.info` is required');
-  }
-  if (!logger.warn) {
-    throw new TypeError('locale: `logger.warn` is required');
-  }
 
   if (preferredSystemLocales.length === 0) {
     logger.warn('locale: `preferredSystemLocales` was empty');
@@ -83,5 +122,10 @@ export function load({
   const matchedLocaleMessages = getLocaleMessages(matchedLocale);
   const englishMessages = getLocaleMessages('en');
 
-  return finalize(matchedLocaleMessages, englishMessages, matchedLocale);
+  return finalize(
+    matchedLocaleMessages,
+    englishMessages,
+    matchedLocale,
+    logger
+  );
 }