🐛 Fix locale detection (#1631)

packages/languages/package.json

@@ -2,6 +2,15 @@
   "name": "@rallly/languages",
   "version": "0.0.0",
   "private": true,
-  "main": "index.ts",
-  "types": "index.ts"
+  "exports": {
+    ".": "./src/index.ts",
+    "./*": "./src/*.ts"
+  },
+  "dependencies": {
+    "@formatjs/intl-localematcher": "^0.6.0",
+    "negotiator": "^1.0.0"
+  },
+  "devDependencies": {
+    "@types/negotiator": "^0.6.3"
+  }
 }

packages/languages/src/get-preferred-locale.ts

@@ -0,0 +1,17 @@
+import languages, { defaultLocale } from "./index";
+import Negotiator from "negotiator";
+import { match } from "@formatjs/intl-localematcher";
+import type { NextRequest } from "next/server";
+
+const locales = Object.keys(languages);
+
+export async function getPreferredLocale(req: NextRequest) {
+  const preferredLanguages = new Negotiator({
+    headers: {
+      "accept-language": req.headers.get("accept-language") ?? "",
+    },
+  }).languages();
+
+  const locale = match(preferredLanguages, locales, defaultLocale);
+  return locale;
+}