Support pagination with Link headers... but of course Soapbox doesn't do that

src/api/home.ts

@@ -1,10 +1,16 @@
+import { z } from '@/deps.ts';
+
 import { fetchFeed, fetchFollows } from '../client.ts';
+import { toStatus } from '../transmute.ts';
 import { getKeys } from '../utils.ts';
 
 import type { Context } from '@/deps.ts';
-import { toStatus } from '../transmute.ts';
+import { LOCAL_DOMAIN } from '../config.ts';
 
 async function homeController(c: Context) {
+  const since = paramSchema.parse(c.req.query('since'));
+  const until = paramSchema.parse(c.req.query('until'));
+
   const keys = getKeys(c);
   if (!keys) {
     return c.json({ error: 'Unauthorized' }, 401);
@@ -15,10 +21,17 @@ async function homeController(c: Context) {
     return c.json([]);
   }
 
-  const events = await fetchFeed(follows);
+  const events = await fetchFeed(follows, { since, until });
   const statuses = (await Promise.all(events.map(toStatus))).filter(Boolean);
 
-  return c.json(statuses);
+  const next = `${LOCAL_DOMAIN}/api/v1/timelines/home?until=${events[events.length - 1].created_at}`;
+  const prev = `${LOCAL_DOMAIN}/api/v1/timelines/home?since=${events[0].created_at}`;
+
+  return c.json(statuses, 200, {
+    link: `<${next}>; rel="next", <${prev}>; rel="prev"`,
+  });
 }
 
+const paramSchema = z.coerce.number().optional().catch(undefined);
+
 export default homeController;

src/client.ts

@@ -3,6 +3,7 @@ import { Author, RelayPool } from '@/deps.ts';
 import { poolRelays } from './config.ts';
 
 import type { Event, SignedEvent } from './event.ts';
+import { eventDateComparator } from './utils.ts';
 
 const pool = new RelayPool(poolRelays);
 
@@ -34,23 +35,40 @@ const fetchFollows = (pubkey: string): Promise<SignedEvent<3> | null> => {
   });
 };
 
-/** Fetch 20 events from people the user follows. */
-function fetchFeed(event3: Event<3>): Promise<SignedEvent<1>[]> {
+interface PaginationParams {
+  since?: number;
+  until?: number;
+  limit?: number;
+}
+
+/** Fetch events from people the user follows. */
+function fetchFeed(event3: Event<3>, params: PaginationParams = {}): Promise<SignedEvent<1>[]> {
+  const limit = params.limit ?? 20;
   const authors = event3.tags.filter((tag) => tag[0] === 'p').map((tag) => tag[1]);
   const results: SignedEvent<1>[] = [];
   authors.push(event3.pubkey); // see own events in feed
 
   return new Promise((resolve) => {
     pool.subscribe(
-      [{ authors, kinds: [1], limit: 20 }],
+      [{
+        authors,
+        kinds: [1],
+        since: params.since,
+        until: params.until,
+        limit,
+      }],
       poolRelays,
       (event: SignedEvent<1> | null) => {
         if (event) {
           results.push(event);
+
+          if (results.length >= limit) {
+            resolve(results.slice(0, limit).sort(eventDateComparator));
+          }
         }
       },
       void 0,
-      () => resolve(results),
+      () => resolve(results.sort(eventDateComparator)),
       { unsubscribeOnEose: true },
     );
   });

src/utils.ts

@@ -1,5 +1,13 @@
 import { Context, getPublicKey } from '@/deps.ts';
 
+import type { Event } from './event.ts';
+
+/** Get the current time in Nostr format. */
+const nostrNow = () => Math.floor(new Date().getTime() / 1000);
+
+/** Pass to sort() to sort events by date. */
+const eventDateComparator = (a: Event, b: Event) => b.created_at - a.created_at;
+
 function getKeys(c: Context) {
   const auth = c.req.headers.get('Authorization') || '';
 
@@ -14,4 +22,4 @@ function getKeys(c: Context) {
   }
 }
 
-export { getKeys };
+export { eventDateComparator, getKeys, nostrNow };