web: redirect tags server side (#1287)

* web: redirect tags server side

* refactor daimoLink parsing func

apps/daimo-web/src/app/l/[[...slug]]/page.tsx

@@ -1,6 +1,7 @@
 /* eslint-disable @next/next/no-img-element */
-import { debugJson } from "@daimo/common";
+import { debugJson, formatDaimoLink, parseDaimoLinkType } from "@daimo/common";
 import { Metadata } from "next";
+import { redirect } from "next/navigation";
 
 import LinkPage from "./LinkPage";
 import { getUrl, LinkPageProps } from "./LinkPageProps";
@@ -25,7 +26,13 @@ export async function generateMetadata(
   const i18n = getI18N(getReqLang());
   const url = getUrl(props);
   const desc = await loadLinkStatusDesc(url);
+
   if (desc == null) return defaultMeta(i18n);
+  if (parseDaimoLinkType(url) === "t" && desc?.linkStatus?.link) {
+    console.log(`[LINK] redirecting tag to ${desc.linkStatus.link}`);
+    redirect(formatDaimoLink(desc.linkStatus.link));
+  }
+
   return createMetadataForLinkStatus(desc);
 }
 

packages/daimo-common/src/daimoLink.ts

@@ -197,7 +197,15 @@ export function parseDaimoLink(link: string): DaimoLink | null {
   }
 }
 
-function parseDaimoLinkInner(link: string): DaimoLink | null {
+export function parseDaimoLinkType(link: string): string | null {
+  const parsedLink = parseDaimoLinkUrl(link);
+  if (parsedLink == null) return null;
+
+  const { parts } = parsedLink;
+  return parts[0];
+}
+
+function parseDaimoLinkUrl(link: string): { url: URL; parts: string[] } | null {
   const prefixes = [
     `${daimoLinkBase}/`,
     `${daimoLinkBaseV2}/`, // New shorter link prefix
@@ -212,6 +220,14 @@ function parseDaimoLinkInner(link: string): DaimoLink | null {
   const suffix = url.pathname.substring(1);
   const parts = suffix.split("/");
 
+  return { url, parts };
+}
+
+function parseDaimoLinkInner(link: string): DaimoLink | null {
+  const parsedLink = parseDaimoLinkUrl(link);
+  if (parsedLink == null) return null;
+  const { url, parts } = parsedLink;
+
   switch (parts[0]) {
     case "account": {
       if (parts.length !== 2) return null;