Refactor auth middleware (#1279)

- Switch to TypeScript
- Use early return
- Switch to regular for loop

Co-authored-by: Geometrically <[email protected]>

apps/frontend/src/middleware/auth.ts

@@ -0,0 +1,35 @@
+const whitelistedParams = ["flow", "error"];
+
+export default defineNuxtRouteMiddleware(async (_to, from) => {
+  const config = useRuntimeConfig();
+  const auth = await useAuth();
+
+  if (auth.value.user) return;
+
+  const fullPath = from.fullPath;
+
+  const url = new URL(fullPath, config.public.apiBaseUrl);
+
+  const extractedParams = Object.create(null) as Record<string, string>;
+
+  for (const param of whitelistedParams) {
+    const val = url.searchParams.get(param);
+    if (val != null) {
+      extractedParams[param] = val;
+      url.searchParams.delete(param);
+    }
+  }
+
+  const redirect = encodeURIComponent(url.pathname + url.search);
+
+  return await navigateTo(
+    {
+      path: "/auth/sign-in",
+      query: {
+        redirect,
+        ...extractedParams,
+      },
+    },
+    { replace: true },
+  );
+});