feat: Show icon on external links (#3100)

* feat: External links get treatment

* cache decorations

shared/utils/urls.ts

@@ -1,5 +1,30 @@
+import { parseDomain } from "./domains";
+
 const env = typeof window !== "undefined" ? window.env : process.env;
 
 export function cdnPath(path: string): string {
   return `${env.CDN_URL}${path}`;
 }
+
+export function isInternalUrl(href: string) {
+  if (href[0] === "/") {
+    return true;
+  }
+  const outline =
+    typeof window !== "undefined"
+      ? parseDomain(window.location.href)
+      : undefined;
+  const parsed = parseDomain(href);
+
+  if (
+    parsed &&
+    outline &&
+    parsed.subdomain === outline.subdomain &&
+    parsed.domain === outline.domain &&
+    parsed.tld === outline.tld
+  ) {
+    return true;
+  }
+
+  return false;
+}