init commit

shared/localization/src/getPageDir.ts

@@ -0,0 +1,40 @@
+/**
+ * TODO: rdar://73010072 (Make localization utils its own package)
+ * Copied from:
+ * https://github.pie.apple.com/amp-ui/desktop-music-app/blob/main/app/utils/page-dir.js
+ */
+
+// these overrides were determined to always show page in RTL, even if the global elements dont contain
+// an he_il entry
+// <rdar://problem/49297213> LOC: IW-IL: RTL: Web Preview Pages: The Preview Pages are not RTL.
+const RTL_LANG_CODES_OVERRIDE = [
+    'he', // hebrew
+];
+
+const RTL_LANG_CODES = [
+    'ar', // arabic
+    'he', // hebrew
+    'ku', // kurdish
+    'ur', // urdu
+    'ps', // pashto
+    'yi', // yiddish
+];
+
+/**
+ * Determine the page-direction for a given locale
+ *
+ * @param {String} localeCode - A string containing a language code and region code separated by a hyphen.
+ * @param {String|undefined|null} langParam - A language code passed from the `l=` query param.
+ */
+export function getPageDir(
+    localeCode: string,
+    langParam: string | undefined | null = null,
+) {
+    const twoLettersLangCode = localeCode.split('-')[0];
+    const isRTLLang = RTL_LANG_CODES.includes(twoLettersLangCode);
+    const isRTLLangOverride =
+        typeof langParam === 'string' &&
+        RTL_LANG_CODES_OVERRIDE.includes(langParam);
+
+    return isRTLLang || isRTLLangOverride ? 'rtl' : 'ltr';
+}