Store link previews in the database

Fixes https://gitlab.com/soapbox-pub/ditto/-/issues/301

packages/db/DittoTables.ts

@@ -1,6 +1,8 @@
 import type { NPostgresSchema } from '@nostrify/db';
 import type { Generated } from 'kysely';
 
+import type { MastodonPreviewCard } from '@ditto/mastoapi/types';
+
 export interface DittoTables extends NPostgresSchema {
   auth_tokens: AuthTokenRow;
   author_stats: AuthorStatsRow;
@@ -34,6 +36,7 @@ interface EventStatsRow {
   quotes_count: number;
   reactions: string;
   zaps_amount: number;
+  link_preview?: MastodonPreviewCard;
 }
 
 interface AuthTokenRow {

packages/db/migrations/053_link_preview.ts

@@ -0,0 +1,9 @@
+import type { Kysely } from 'kysely';
+
+export async function up(db: Kysely<unknown>): Promise<void> {
+  await db.schema.alterTable('event_stats').addColumn('link_preview', 'jsonb').execute();
+}
+
+export async function down(db: Kysely<unknown>): Promise<void> {
+  await db.schema.alterTable('event_stats').dropColumn('link_preview').execute();
+}

packages/ditto/controllers/api/trends.ts

@@ -7,7 +7,6 @@ import { z } from 'zod';
 import { AppController } from '@/app.ts';
 import { hydrateEvents } from '@/storages/hydrate.ts';
 import { generateDateRange, Time } from '@/utils/time.ts';
-import { unfurlCardCached } from '@/utils/unfurl.ts';
 import { errorJson } from '@/utils/log.ts';
 import { renderStatus } from '@/views/mastodon/statuses.ts';
 
@@ -94,9 +93,8 @@ const trendingLinksController: AppController = async (c) => {
 async function getTrendingLinks(conf: DittoConf, relay: NStore): Promise<TrendingLink[]> {
   const trends = await getTrendingTags(relay, 'r', await conf.signer.getPublicKey());
 
-  return Promise.all(trends.map(async (trend) => {
+  return Promise.all(trends.map((trend) => {
     const link = trend.value;
-    const card = await unfurlCardCached(link);
 
     const history = trend.history.map(({ day, authors, uses }) => ({
       day: String(day),
@@ -119,7 +117,6 @@ async function getTrendingLinks(conf: DittoConf, relay: NStore): Promise<Trendin
       image: null,
       embed_url: '',
       blurhash: null,
-      ...card,
       history,
     };
   }));

packages/ditto/interfaces/DittoEvent.ts

@@ -1,6 +1,8 @@
 import { NostrEvent } from '@nostrify/nostrify';
 import { LanguageCode } from 'iso-639-1';
 
+import type { MastodonPreviewCard } from '@ditto/mastoapi/types';
+
 /** Ditto internal stats for the event's author. */
 export interface AuthorStats {
   followers_count: number;
@@ -22,6 +24,7 @@ export interface EventStats {
   quotes_count: number;
   reactions: Record<string, number>;
   zaps_amount: number;
+  link_preview?: MastodonPreviewCard;
 }
 
 /** Internal Event representation used by Ditto, including extra keys. */

packages/ditto/storages/DittoRelayStore.ts

@@ -41,7 +41,7 @@ import { fetchFavicon, insertFavicon, queryFavicon } from '@/utils/favicon.ts';
 import { lookupNip05 } from '@/utils/nip05.ts';
 import { parseNoteContent, stripimeta } from '@/utils/note.ts';
 import { SimpleLRU } from '@/utils/SimpleLRU.ts';
-import { unfurlCardCached } from '@/utils/unfurl.ts';
+import { unfurlCard } from '@/utils/unfurl.ts';
 import { renderWebPushNotification } from '@/views/mastodon/push.ts';
 
 interface DittoRelayStoreOpts {
@@ -217,10 +217,11 @@ export class DittoRelayStore implements NRelay {
       await relay.event(purifyEvent(event), { signal });
     } finally {
       // This needs to run in steps, and should not block the API from responding.
+      const signal = AbortSignal.timeout(3000);
       Promise.allSettled([
         this.handleZaps(event),
         this.updateAuthorData(event, signal),
-        this.prewarmLinkPreview(event, signal),
+        this.warmLinkPreview(event, signal),
         this.generateSetEvents(event),
       ])
         .then(() =>
@@ -428,12 +429,34 @@ export class DittoRelayStore implements NRelay {
     }
   }
 
-  private async prewarmLinkPreview(event: NostrEvent, signal?: AbortSignal): Promise<void> {
+  private async warmLinkPreview(event: NostrEvent, signal?: AbortSignal): Promise<void> {
+    const { db, conf } = this.opts;
+
     if (event.kind === 1) {
       const { firstUrl } = parseNoteContent(stripimeta(event.content, event.tags), [], this.opts);
 
+      console.log({ firstUrl });
+
       if (firstUrl) {
-        await unfurlCardCached(firstUrl, signal);
+        const linkPreview = await unfurlCard(firstUrl, { conf, signal });
+
+        console.log(linkPreview);
+
+        if (linkPreview) {
+          await db.kysely.insertInto('event_stats')
+            .values({
+              event_id: event.id,
+              replies_count: 0,
+              reposts_count: 0,
+              reactions_count: 0,
+              quotes_count: 0,
+              reactions: '{}',
+              zaps_amount: 0,
+              link_preview: linkPreview,
+            })
+            .onConflict((oc) => oc.column('event_id').doUpdateSet({ link_preview: linkPreview }))
+            .execute();
+        }
       }
     }
   }

packages/ditto/storages/hydrate.ts

@@ -411,6 +411,7 @@ async function gatherEventStats(
     quotes_count: Math.max(0, row.quotes_count),
     reactions: row.reactions,
     zaps_amount: Math.max(0, row.zaps_amount),
+    link_preview: row.link_preview,
   }));
 }
 

packages/ditto/utils/unfurl.ts

@@ -1,23 +1,27 @@
-import { cachedLinkPreviewSizeGauge } from '@ditto/metrics';
-import TTLCache from '@isaacs/ttlcache';
 import { logi } from '@soapbox/logi';
 import { safeFetch } from '@soapbox/safe-fetch';
 import DOMPurify from 'isomorphic-dompurify';
 import { unfurl } from 'unfurl.js';
 
-import { Conf } from '@/config.ts';
 import { errorJson } from '@/utils/log.ts';
 
+import type { DittoConf } from '@ditto/conf';
 import type { MastodonPreviewCard } from '@ditto/mastoapi/types';
 
-async function unfurlCard(url: string, signal: AbortSignal): Promise<MastodonPreviewCard | null> {
+interface UnfurlCardOpts {
+  conf: DittoConf;
+  signal?: AbortSignal;
+}
+
+export async function unfurlCard(url: string, opts: UnfurlCardOpts): Promise<MastodonPreviewCard | null> {
+  const { conf, signal } = opts;
   try {
     const result = await unfurl(url, {
       fetch: (url) =>
         safeFetch(url, {
           headers: {
             'Accept': 'text/html, application/xhtml+xml',
-            'User-Agent': Conf.fetchUserAgent,
+            'User-Agent': conf.fetchUserAgent,
           },
           signal,
         }),
@@ -54,19 +58,3 @@ async function unfurlCard(url: string, signal: AbortSignal): Promise<MastodonPre
     return null;
   }
 }
-
-/** TTL cache for preview cards. */
-const previewCardCache = new TTLCache<string, Promise<MastodonPreviewCard | null>>(Conf.caches.linkPreview);
-
-/** Unfurl card from cache if available, otherwise fetch it. */
-export function unfurlCardCached(url: string, signal = AbortSignal.timeout(1000)): Promise<MastodonPreviewCard | null> {
-  const cached = previewCardCache.get(url);
-  if (cached !== undefined) {
-    return cached;
-  } else {
-    const card = unfurlCard(url, signal);
-    previewCardCache.set(url, card);
-    cachedLinkPreviewSizeGauge.set(previewCardCache.size);
-    return card;
-  }
-}

packages/ditto/views/mastodon/statuses.ts

@@ -6,7 +6,6 @@ import { type DittoEvent } from '@/interfaces/DittoEvent.ts';
 import { nostrDate } from '@/utils.ts';
 import { getMediaLinks, parseNoteContent, stripimeta } from '@/utils/note.ts';
 import { findReplyTag } from '@/utils/tags.ts';
-import { unfurlCardCached } from '@/utils/unfurl.ts';
 import { accountFromPubkey, renderAccount } from '@/views/mastodon/accounts.ts';
 import { renderAttachment } from '@/views/mastodon/attachments.ts';
 import { renderEmojis } from '@/views/mastodon/emojis.ts';
@@ -42,21 +41,17 @@ async function renderStatus(
 
   const mentions = event.mentions?.map((event) => renderMention(event)) ?? [];
 
-  const { html, links, firstUrl } = parseNoteContent(stripimeta(event.content, event.tags), mentions, { conf: Conf });
+  const { html, links } = parseNoteContent(stripimeta(event.content, event.tags), mentions, { conf: Conf });
 
-  const [card, relatedEvents] = await Promise
-    .all([
-      firstUrl ? unfurlCardCached(firstUrl, AbortSignal.timeout(500)) : null,
-      viewerPubkey
-        ? await store.query([
-          { kinds: [6], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
-          { kinds: [7], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
-          { kinds: [9734], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
-          { kinds: [10001], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
-          { kinds: [10003], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
-        ])
-        : [],
-    ]);
+  const relatedEvents = viewerPubkey
+    ? await store.query([
+      { kinds: [6], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
+      { kinds: [7], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
+      { kinds: [9734], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
+      { kinds: [10001], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
+      { kinds: [10003], '#e': [event.id], authors: [viewerPubkey], limit: 1 },
+    ])
+    : [];
 
   const reactionEvent = relatedEvents.find((event) => event.kind === 7);
   const repostEvent = relatedEvents.find((event) => event.kind === 6);
@@ -93,10 +88,12 @@ async function renderStatus(
 
   const expiresAt = new Date(Number(event.tags.find(([name]) => name === 'expiration')?.[1]) * 1000);
 
+  console.log(event);
+
   return {
     id: event.id,
     account,
-    card,
+    card: event.event_stats?.link_preview ?? null,
     content: compatMentions + html,
     created_at: nostrDate(event.created_at).toISOString(),
     in_reply_to_id: replyId ?? null,