rewrite metadata generation

src/controllers/frontend.ts

@@ -1,8 +1,8 @@
 import { AppMiddleware } from '@/app.ts';
 import { Conf } from '@/config.ts';
-import { html } from '@/utils/html.ts';
 import { Storages } from '@/storages.ts';
 import {
+  getHandle,
   getPathParams,
   getProfileInfo,
   getStatusInfo,
@@ -10,6 +10,7 @@ import {
   PathParams,
 } from '@/utils/og-metadata.ts';
 import { getInstanceMetadata } from '@/utils/instance.ts';
+import { metadataView } from '@/views/meta.ts';
 
 /** Placeholder to find & replace with metadata. */
 const META_PLACEHOLDER = '<!--server-generated-meta-->' as const;
@@ -18,88 +19,34 @@ const META_PLACEHOLDER = '<!--server-generated-meta-->' as const;
  * TODO: implement caching for posts (LRUCache)
  */
 
-/**
- * Builds a series of meta tags from supplied metadata for injection into the served HTML page.
- * @param opts the metadata to use to fill the template.
- * @returns the built OpenGraph metadata.
- */
-const tpl = ({ title, type, url, image, description, site }: OpenGraphTemplateOpts): string => {
-  const res = [];
-  res.push(html`\
-  <meta content="${title}" property="og:title">
-  <meta content="${type}" property="og:type">
-  <meta content="${url}" property="og:url">
-  <meta content="${description}" property="og:description">
-  <meta content="${site}" property="og:site_name">
-  <meta name="twitter:card" content="summary">
-  <meta name="twitter:title" content="${title}">
-  <meta name="twitter:description" content="${description}">
-  `);
-
-  if (image) {
-    res.push(html`\
-    <meta content="${image.url}" property="og:image">
-    <meta content="${image.w}" property="og:image:width">
-    <meta content="${image.h}" property="og:image:height">
-    <meta name="twitter:image" content="${image.url}">
-    `);
-    if (image.alt) {
-      res.push(html`<meta content="${image.alt}" property="og:image:alt">`);
-      res.push(html`<meta content="${image.alt}" property="twitter:image:alt">`);
-    }
-  }
-
-  return res.join('\n').replace(/\n+/g, '\n').replace(/^[ ]+/gm, '');
-};
-
 const store = await Storages.db();
 
-async function buildMetaTags(params: PathParams, url: string): Promise<string> {
-  // should never happen
-  if (!params.acct && !params.statusId) return '';
-
+async function buildTemplateOpts(params: PathParams, url: string): Promise<OpenGraphTemplateOpts> {
   const meta = await getInstanceMetadata(store);
-  const kind0 = await getProfileInfo(params.acct);
-  const { description, image } = await getStatusInfo(params.statusId || '');
-  const handle = kind0.nip05?.replace(/^_@/, '') || kind0.name || 'npub1xxx';
+  const res: OpenGraphTemplateOpts = {
+    title: `View this page on ${meta.name}`,
+    type: 'article',
+    description: meta.about,
+    url,
+    site: meta.name,
+  };
 
-  if (params.acct && params.statusId) {
-    return tpl({
-      title: `View @${handle}'s post on Ditto`,
-      type: 'article',
-      image,
-      description,
-      url,
-      site: meta.name,
-    });
-  } else if (params.acct) {
-    return tpl({
-      title: `View @${handle}'s profile on Ditto`,
-      type: 'profile',
-      description: kind0.about || '',
-      url,
-      site: meta.name,
-      image: kind0.picture
-        ? {
-          url: kind0.picture,
-          // Time will tell if this is fine.
-          h: 150,
-          w: 150,
-        }
-        : undefined,
-    });
+  if (params.acct && !params.statusId) {
+    const profile = await getProfileInfo(params.acct);
+    res.type = 'profile';
+    res.title = `View @${await getHandle(params.acct)}'s profile on Ditto`;
+    res.description = profile.about;
+    if (profile.picture) {
+      res.image = { url: profile.picture, h: 150, w: 150 };
+    }
   } else if (params.statusId) {
-    return tpl({
-      title: `View post on Ditto`,
-      type: 'profile',
-      description,
-      image,
-      url,
-      site: meta.name,
-    });
+    const { description, image, title } = await getStatusInfo(params.statusId);
+    res.description = description;
+    res.image = image;
+    res.title = title;
   }
 
-  return '';
+  return res;
 }
 
 export const frontendController: AppMiddleware = async (c, next) => {
@@ -109,7 +56,7 @@ export const frontendController: AppMiddleware = async (c, next) => {
       const params = getPathParams(c.req.path);
 
       if (params) {
-        const meta = await buildMetaTags(params, Conf.local(c.req.path));
+        const meta = metadataView(await buildTemplateOpts(params, Conf.local(c.req.path)));
         return c.html(content.replace(META_PLACEHOLDER, meta));
       }
     }

src/utils/og-metadata.ts

@@ -1,8 +1,9 @@
 import { NostrMetadata, NSchema as n } from '@nostrify/nostrify';
-import { getAuthor, getEvent } from '@/queries.ts';
-import { nip05Cache } from '@/utils/nip05.ts';
+import { getEvent } from '@/queries.ts';
 import { match } from 'path-to-regexp';
 import { nip19 } from 'nostr-tools';
+import { lookupAccount, lookupPubkey } from '@/utils/lookup.ts';
+import { parseAndVerifyNip05 } from '@/utils/nip05.ts';
 
 export interface OpenGraphTemplateOpts {
   title: string;
@@ -16,6 +17,7 @@ export interface OpenGraphTemplateOpts {
 export type PathParams = Partial<Record<'statusId' | 'acct' | 'note' | 'nevent' | 'nprofile' | 'npub', string>>;
 
 interface StatusInfo {
+  title: string;
   description: string;
   image?: {
     url: string;
@@ -65,70 +67,57 @@ export function getPathParams(path: string) {
   }
 }
 
-async function urlParamToPubkey(handle: string) {
-  const id = `${handle}`;
-  const parts = id.match(/(?:(.+)@)?(.+)/);
-  if (parts) {
-    const key = `${parts[1] ? (parts[1] + '@') : ''}${parts[2]}`;
-    return await nip05Cache.fetch(key, { signal: AbortSignal.timeout(1000) }).then((res) => res.pubkey);
-  } else if (id.startsWith('npub1')) {
-    return nip19.decode(id as `npub1${string}`).data;
-  } else if (/(?:[0-9]|[a-f]){64}/.test(id)) {
-    return id;
-  }
+type ProfileInfo = { name: string; about: string } & NostrMetadata;
 
-  // shouldn't ever happen for a well-formed link
-  return '';
+/**
+ * Look up the name and bio of a user for use in generating OpenGraph metadata.
+ *
+ * @param handle The bech32 / nip05 identifier for the user, obtained from the URL.
+ * @returns An object containing the `name` and `about` fields of the user's kind 0,
+ * or sensible defaults if the kind 0 has those values missing.
+ */
+export async function getProfileInfo(handle: string | undefined): Promise<ProfileInfo> {
+  const acc = await lookupAccount(handle || '');
+  if (!acc) throw new Error('Invalid handle specified, or account not found.');
+
+  const short = nip19.npubEncode(acc.id).slice(0, 8);
+  const { name = short, about = `@${short}'s Nostr profile` } = n.json().pipe(n.metadata()).parse(acc.content);
+
+  return { name, about };
 }
 
-export async function getProfileInfo(handle: string | undefined): Promise<NostrMetadata> {
-  const id = await urlParamToPubkey(handle || '');
-  const kind0 = await getAuthor(id);
-
-  const short = nip19.npubEncode(id).substring(0, 8);
-  const blank = { name: short, about: `@${short}'s ditto profile` };
-  if (!kind0) return blank;
-
-  return Object.assign(
-    blank,
-    n.json().pipe(n.metadata()).parse(kind0.content),
-  );
-}
-
-const truncate = (s: string, len: number, ellipsis = '...') => {
+function truncate(s: string, len: number, ellipsis = '…') {
   if (s.length <= len) return s;
   return s.slice(0, len) + ellipsis;
-};
+}
 
-export async function getStatusInfo(id: string | undefined, handle?: string): Promise<StatusInfo> {
-  const event = await getEvent(id || '');
-  if (!event || !id) {
-    return { description: `A post on Ditto by @${handle}` };
-  }
+export async function getHandle(id: string, name?: string | undefined) {
+  const pubkey = /[a-z][0-9]{64}/.test(id) ? id : await lookupPubkey(id);
+  if (!pubkey) throw new Error('Invalid user identifier');
+  const parsed = await parseAndVerifyNip05(id, pubkey);
+  return parsed?.handle || name || 'npub1xxx';
+}
 
+export async function getStatusInfo(id: string): Promise<StatusInfo> {
+  const event = await getEvent(id);
+  if (!id || !event) throw new Error('Invalid post id supplied');
+
+  const handle = await getHandle(event.pubkey);
   const res: StatusInfo = {
+    title: `View @${handle}'s post on Ditto`,
     description: event.content
       .replace(/nostr:(npub1(?:[0-9]|[a-z]){58})/g, (_, key: string) => `@${key.slice(0, 8)}`),
   };
 
-  let url: string;
-  let w: number;
-  let h: number;
+  const data: string[][] = event.tags
+    .find(([name]) => name === 'imeta')?.slice(1)
+    .map((entry: string) => entry.split(' ')) ?? [];
 
-  for (const [tag, ...values] of event.tags) {
-    if (tag !== 'imeta') continue;
-    for (const value of values) {
-      const [item, datum] = value.split(' ');
-      if (!['dim', 'url'].includes(item)) continue;
-      if (item === 'dim') {
-        [w, h] = datum.split('x').map(Number);
-      } else if (item === 'url') {
-        url = datum;
-      }
-    }
-  }
+  const url = data.find(([name]) => name === 'url')?.[1];
+  const dim = data.find(([name]) => name === 'dim')?.[1];
+
+  const [w, h] = dim?.split('x').map(Number) ?? [null, null];
 
-  // @ts-ignore conditional assign
   if (url && w && h) {
     res.image = { url, w, h };
     res.description = res.description.replace(url.trim(), '');