Add collection rss

packages/atproto-browser/app/at/page.tsx

@@ -57,7 +57,10 @@ export default async function AtPage({
     return (
       <div>
         <h1>
-          {handle}&apos;s {uri.collection} records
+          {handle}&apos;s {uri.collection} records{" "}
+          <Link href={`/collection-rss?u=${uri.toString()}`} title="RSS feed">
+            🛜
+          </Link>
         </h1>
         <ul>
           <SWRConfig

packages/atproto-browser/app/collection-rss/route.tsx

@@ -0,0 +1,70 @@
+import { listRecords } from "@/lib/atproto";
+import { resolveIdentity } from "@/lib/atproto-server";
+import { getHandle, getPds } from "@atproto/identity";
+import { AtUri } from "@atproto/syntax";
+
+export const revalidate = 60;
+
+const ORIGIN = "https://atproto-browser.vercel.app";
+
+export async function GET(request: Request) {
+  const uri = new AtUri(new URL(request.url).searchParams.get("u")!);
+  if (!uri.origin || uri.rkey) {
+    return new Response("Invalid collection URI", { status: 400 });
+  }
+  const identityResult = await resolveIdentity(uri.host);
+  if (!identityResult.success) {
+    return new Response(identityResult.error, { status: 400 });
+  }
+
+  const didDoc = identityResult.identity;
+  const pds = getPds(didDoc);
+  if (!pds) {
+    return new Response(`No PDS found for ${didDoc.id}`, { status: 400 });
+  }
+  const handle = getHandle(didDoc);
+  if (!handle) {
+    return new Response(`No handle found for ${didDoc.id}`, { status: 400 });
+  }
+
+  const { records } = await listRecords(pds, didDoc.id, uri.collection);
+
+  const rss = `
+  <rss version="2.0">
+    <channel>
+      <title>@${handle}'s ${uri.collection} atproto records</title>
+      <link>${ORIGIN}/collection-rss?u=${uri.toString()}</link>
+      <description>Collection ${uri.collection} from ${uri.origin}</description>
+      <language>en-gb</language>
+      <ttl>60</ttl>
+      ${records
+        .map((record) =>
+          `
+          <item>
+            <title>${cdata(`New ${uri.collection}: ${new AtUri(record.uri).rkey}`)}</title>
+            <pubDate>${new Intl.DateTimeFormat("fr-CA", {
+              year: "numeric",
+              month: "2-digit",
+              day: "2-digit",
+            }).format(new Date())}</pubDate>
+            <link>${ORIGIN}/collection-rss?u=${uri.toString()}</link>
+            <guid isPermalink="false">${record.cid}</guid>
+          </item>
+        `.trim(),
+        )
+        .join("\n")}
+    </channel>
+  </rss>
+`.trim();
+
+  return new Response(rss, {
+    headers: {
+      "Content-Type": "application/xml",
+      "Content-Length": String(new TextEncoder().encode(rss).length),
+    },
+  });
+}
+
+function cdata(s: string) {
+  return `<![CDATA[${s}]]>`;
+}