source: Klonkt/src/routes/activitypub.js@ 8f8b40f

/**
 * ActivityPub — public endpoints (Phase 1: discover + fetch).
 *
 *   GET /.well-known/webfinger?resource=acct:<slug>@<host>
 *   GET /ap/users/:slug            actor (content-negotiated: AP-JSON vs redirect to HTML profile)
 *   GET /ap/users/:slug/outbox     OrderedCollection of Create(Note)
 *   GET /ap/users/:slug/followers  count-only OrderedCollection
 *   GET /ap/users/:slug/featured   pinned posts (Mastodon "Featured" tab)
 *   GET /ap/notes/:id              a single Note
 *   POST /ap/users/:slug/inbox, /ap/inbox  → 202 (Follow/Accept + signature verify: next step)
 *
 * Mounted before resolveSite; resolves the site by slug itself.
 */
import express from 'express';
import { readFileSync } from 'fs';
import db from '../config/database.js';
import AP from '../services/ActivityPubService.js';
import { apReadLimiter, apInboxLimiter } from '../middleware/rate-limit.js';
import { apEnabled } from '../services/SettingsService.js';
import OAuth from '../services/OAuthService.js';
import * as Guardianship from '../services/guardianship/index.js';
import multer from 'multer';
import path from 'path';
import fs from 'fs';
import { fileURLToPath } from 'url';
import { randomUUID } from 'crypto';

const router = express.Router();
// The whole fediverse layer can be turned off (solo "no federation" mode):
// then /ap/*, WebFinger and NodeInfo are simply gone — the site is undiscoverable
// and unfederatable. CRITICAL: this router is mounted at root (app.use(apRoutes)), so a
// blanket res.status(404) here ran for EVERY request and 404'd the whole site when AP was
// off. Use next('router') to SKIP this router entirely and let the normal routes handle it
// (the /ap/* paths then fall through to the app's normal 404, which is correct).
router.use((req, res, next) => { if (!apEnabled()) return next('router'); next(); });
// Generous per-IP baseline over all /ap/* (reads). The inbox POST gets an
// additional, tighter cap inline (it triggers outbound fetches).
router.use(apReadLimiter);
let _ver = '1.0.0';
try { _ver = JSON.parse(readFileSync(new URL('../../package.json', import.meta.url))).version || _ver; } catch { /* keep default */ }

const baseUrl = (req) => (process.env.PUBLIC_BASE_URL || `${req.protocol}://${req.get('host')}`).replace(/\/+$/, '');
const hostOf = (req) => { try { return new URL(baseUrl(req)).host; } catch { return req.get('host'); } };
const publicSite = (slug) => db.prepare('SELECT * FROM sites WHERE slug = ? AND (is_public IS NULL OR is_public = 1)').get(slug);
const primarySlug = () => { const r = db.prepare('SELECT slug FROM sites WHERE is_primary = 1').get(); return r && r.slug; };

// ── WebFinger ─────────────────────────────────────────────────────
router.get('/.well-known/webfinger', (req, res) => {
  const m = String(req.query.resource || '').match(/^acct:([^@]+)@(.+)$/i);
  if (!m) return res.status(400).type('text/plain').send('bad resource');
  const site = publicSite(m[1]);
  if (!site) return res.status(404).end();
  res.type('application/jrd+json; charset=utf-8');
  res.set('Cache-Control', 'public, max-age=300');
  const actorUri = AP.actorId(baseUrl(req), site.slug);
  const profileUrl = baseUrl(req) + (site.slug === primarySlug() ? '/' : `/user/${encodeURIComponent(site.slug)}`);
  res.send(JSON.stringify({
    subject: `acct:${site.slug}@${hostOf(req)}`,
    aliases: [actorUri, profileUrl],
    links: [
      { rel: 'self', type: 'application/activity+json', href: actorUri },
      { rel: 'http://webfinger.net/rel/profile-page', type: 'text/html', href: profileUrl },
    ],
  }));
});

// ── Actor ─────────────────────────────────────────────────────────
router.get('/ap/users/:slug', (req, res) => {
  const site = publicSite(req.params.slug);
  if (!site) return res.status(404).end();
  if (!AP.apWants(req)) {
    // A browser hit the AP actor URL → send them to the human profile.
    const human = site.slug === primarySlug() ? '/' : `/user/${encodeURIComponent(site.slug)}`;
    return res.redirect(302, baseUrl(req) + human);
  }
  site.primary_slug = primarySlug();
  AP.sendAP(res, AP.buildActor(baseUrl(req), site));
});

// ── Outbox ────────────────────────────────────────────────────────
router.get('/ap/users/:slug/outbox', async (req, res) => {
  const site = publicSite(req.params.slug);
  if (!site) return res.status(404).end();
  // Authorized fetch (FEP-633c §5.3 note): a committed guardian doing a SIGNED
  // GET may read the ward's fan-only history too, without appearing as a
  // follower. Unsigned / non-guardian callers get the public collection only.
  let asGuardian = false;
  if (req.headers['signature']) {
    const verified = await AP.verifyRequest(req).catch(() => null);
    asGuardian = !!(verified && AP.isWardGuardian(req.params.slug, verified.id));
  }
  const fanClause = asGuardian ? '' : "AND (fan_only IS NULL OR fan_only = 0)";
  const posts = db.prepare(
    `SELECT id, slug, title, content, cover_image_url, cover_video_url, nsfw, content_warning, published_at, created_at
     FROM posts WHERE site_id = ? AND status = 'published' ${fanClause}
     ORDER BY COALESCE(published_at, created_at) DESC LIMIT 20`
  ).all(site.id);
  AP.sendAP(res, AP.buildOutbox(baseUrl(req), site, posts), asGuardian ? 'private, no-store' : undefined);
});

// ── Blocked collection (owner only, AP §5.6) ──────────────────────
// The server blocklist is the source of truth for Shaer's "in Orbit":
// clients read it here instead of keeping their own state. Actor-kind
// blocks only (domain blocks are instance policy, not an Orbit member).
router.get('/ap/users/:slug/blocked', (req, res) => {
  const auth = OAuth.verifyBearer(req.headers.authorization);
  if (!auth || auth.site.slug !== req.params.slug) return res.status(403).end();
  const base = baseUrl(req);
  const items = AP.listBlocks(auth.site.slug)
    .filter((b) => b.kind === 'actor')
    .map((b) => b.target);
  AP.sendAP(res, {
    '@context': AP.AP_CONTEXT,
    id: `${base}/ap/users/${auth.site.slug}/blocked`,
    type: 'OrderedCollection',
    totalItems: items.length,
    orderedItems: items,
  });
});

// ── Guardian queues (owner only, FEP-633c, shaer:queues) ──────────
// The dashboard collections the Shaer clients read: pending adoption offers,
// gated follows (empty in Klonkt for now) and the guardian's wards. Same
// contract as the Shaer test daemon.
function queueRoute(name, build) {
  router.get(`/ap/users/:slug/queues/${name}`, (req, res) => {
    const auth = OAuth.verifyBearer(req.headers.authorization);
    if (!auth || auth.site.slug !== req.params.slug) return res.status(403).end();
    const base = baseUrl(req);
    const me = `${base}/ap/users/${auth.site.slug}`;
    AP.sendAP(res, { '@context': AP.AP_CONTEXT, ...build(`${me}/queues/${name}`, auth.site.slug, me) });
  });
}
queueRoute('offers', (id, slug, me) => Guardianship.offersCollection(id, slug, me));
queueRoute('follows', (id) => Guardianship.followsCollection(id));
queueRoute('wards', (id, slug) => Guardianship.wardsCollection(id, slug));

// ── Inbox read (owner only, AP C2S) ───────────────────────────────
// GET on the inbox is part of ActivityPub C2S: the account owner (a bearer
// scoped to this site) reads recent inbound posts (the timeline: accounts
// they follow) as Create(Note) items, so an app (Shaer) can build a unified
// feed. Anyone else gets 403; the inbox stays write-only for the public.
router.get('/ap/users/:slug/inbox', (req, res) => {
  const auth = OAuth.verifyBearer(req.headers.authorization);
  if (!auth || auth.site.slug !== req.params.slug) return res.status(403).end();
  const base = baseUrl(req);
  const items = AP.getTimeline(auth.site.slug, 60).map((t) => ({
    id: `${t.id}#create`,
    type: 'Create',
    actor: t.author_uri,
    published: t.published || t.created_at || undefined,
    object: {
      id: t.id,
      type: 'Note',
      attributedTo: t.author_uri,
      content: t.content,
      url: t.url || undefined,
      published: t.published || t.created_at || undefined,
      sensitive: !!t.nsfw,
      summary: t.cw || undefined,
      // Friends' media travels along (media_json → AS2 attachment), so the
      // client renders their images/audio like own outbox posts.
      attachment: AP.timelineAttachments(t.media_json),
      // FEP-9098 custom emojis: the note's Emoji tags, so the client can
      // render :shortcode: as an image instead of literal text.
      tag: AP.timelineEmojis(t.emoji_json),
    },
  }));
  AP.sendAP(res, {
    '@context': AP.AP_CONTEXT,
    id: `${base}/ap/users/${auth.site.slug}/inbox`,
    type: 'OrderedCollection',
    totalItems: items.length,
    orderedItems: items,
  });
});

// ── uploadMedia (owner only, AP C2S) ──────────────────────────────
// The actor advertises endpoints.uploadMedia; this implements it. A bearer
// scoped to this site uploads one image/audio/video (multipart field "file",
// AP convention) into the same store the reply editor uses, and gets back
// { url, mediaType, name } to attach on a note (e.g. the help-buoy capture).
const AP_MEDIA_DIR = path.resolve(
  process.env.REPLY_MEDIA_PATH ||
  path.join(path.dirname(fileURLToPath(import.meta.url)), '..', '..', 'storage', 'media', 'reply-media')
);
fs.mkdirSync(AP_MEDIA_DIR, { recursive: true });
const AP_MEDIA_EXT = new Set(['.jpg', '.jpeg', '.png', '.webp', '.gif', '.mp3', '.m4a', '.ogg', '.opus', '.flac', '.wav', '.mp4', '.webm', '.mov']);
const apMediaUpload = multer({
  storage: multer.diskStorage({
    destination: (req, file, cb) => cb(null, AP_MEDIA_DIR),
    filename: (req, file, cb) => cb(null, `${randomUUID()}${path.extname(file.originalname || '').toLowerCase()}`),
  }),
  limits: { fileSize: 32 * 1024 * 1024 },
  fileFilter: (req, file, cb) => {
    const ext = path.extname(file.originalname || '').toLowerCase();
    if (!AP_MEDIA_EXT.has(ext)) return cb(new Error('Media must be an image, audio or video file'));
    cb(null, true);
  },
});
router.post('/ap/users/:slug/uploadMedia', (req, res) => {
  const auth = OAuth.verifyBearer(req.headers.authorization);
  if (!auth || auth.site.slug !== req.params.slug) return res.status(403).end();
  apMediaUpload.single('file')(req, res, (err) => {
    if (err) return res.status(400).json({ error: err.message });
    if (!req.file) return res.status(400).json({ error: 'No file' });
    const mime = String(req.file.mimetype || '');
    if (!/^(image|audio|video)\//.test(mime)) {
      try { fs.unlinkSync(req.file.path); } catch { /* best effort */ }
      return res.status(400).json({ error: 'Media must be an image, audio or video file' });
    }
    res.status(201).json({
      url: '/media/reply-media/' + req.file.filename,
      mediaType: mime,
      name: String(req.file.originalname || '').slice(0, 120),
    });
  });
});

// ── Followers (count-only public, full for the owner) ─────────────
// A C2S bearer scoped to this site (the account owner) gets the real actor
// URIs so their own client can build a friends list; everyone else gets the
// count only (privacy).
// FEP-9876: enrichment is opt-in via `Prefer: return=representation` (RFC 7240).
// Returns true and sets the response headers when the owner asked for it.
function wantsEnriched(req, res) {
  res.set('Vary', 'Prefer');   // enriched and bare are two representations
  if (AP.prefersEnriched(req.get('Prefer'))) {
    res.set('Preference-Applied', 'return=representation');
    return true;
  }
  return false;
}

router.get('/ap/users/:slug/followers', (req, res) => {
  const auth = OAuth.verifyBearer(req.headers.authorization);
  const owner = auth && auth.site.slug === req.params.slug;
  const site = owner ? auth.site : publicSite(req.params.slug);
  if (!site) return res.status(404).end();
  if (owner) {
    const uris = db.prepare('SELECT actor_uri FROM ap_followers WHERE slug = ? ORDER BY created_at').all(site.slug).map((r) => r.actor_uri);
    // Default = bare references; enrich only when the client asks (FEP-9876).
    const items = wantsEnriched(req, res) ? uris.map((u) => AP.buildActorRef(site.slug, u)) : uris;
    return AP.sendAP(res, AP.buildFollowers(baseUrl(req), site, items.length, items));
  }
  const n = db.prepare('SELECT COUNT(*) n FROM ap_followers WHERE slug = ?').get(site.slug).n;
  AP.sendAP(res, AP.buildFollowers(baseUrl(req), site, n));
});

// ── Following (count-only public, full for the owner) ─────────────
router.get('/ap/users/:slug/following', (req, res) => {
  const auth = OAuth.verifyBearer(req.headers.authorization);
  const owner = auth && auth.site.slug === req.params.slug;
  const site = owner ? auth.site : publicSite(req.params.slug);
  if (!site) return res.status(404).end();
  if (owner) {
    const enrich = wantsEnriched(req, res);   // FEP-9876 opt-in
    let items = [];
    try {
      const uris = db.prepare("SELECT actor_uri FROM ap_following WHERE slug = ? AND status = 'accepted' ORDER BY created_at").all(site.slug).map((r) => r.actor_uri);
      items = enrich ? uris.map((u) => AP.buildActorRef(site.slug, u)) : uris;
    } catch { /* table may not exist */ }
    return AP.sendAP(res, AP.buildFollowing(baseUrl(req), site, items.length, items));
  }
  let n = 0;
  try { n = db.prepare("SELECT COUNT(*) n FROM ap_following WHERE slug = ? AND status = 'accepted'").get(site.slug).n; } catch { /* table may not exist */ }
  AP.sendAP(res, AP.buildFollowing(baseUrl(req), site, n));
});

// ── Featured (pinned posts → Mastodon "Featured" tab) ─────────────
router.get('/ap/users/:slug/featured', (req, res) => {
  const site = publicSite(req.params.slug);
  if (!site) return res.status(404).end();
  // NB: Mastodon DISPLAYS the featured collection in REVERSE (pins shown
  // last-processed-first). So we emit it reversed (lowest pin priority first,
  // rank 1 last) → Mastodon flips it back to pin-rank ascending on the profile.
  const posts = db.prepare(
    `SELECT id, slug, title, content, cover_image_url, cover_video_url, nsfw, content_warning, published_at, created_at
     FROM posts WHERE site_id = ? AND status = 'published' AND (fan_only IS NULL OR fan_only = 0)
       AND pinned IS NOT NULL AND pinned > 0
     ORDER BY pinned DESC, COALESCE(published_at, created_at) ASC LIMIT 20`
  ).all(site.id);
  AP.sendAP(res, AP.buildFeatured(baseUrl(req), site, posts));
});

// ── Note ──────────────────────────────────────────────────────────
router.get('/ap/notes/:id', (req, res) => {
  const post = db.prepare(
    "SELECT * FROM posts WHERE id = ? AND status = 'published' AND (fan_only IS NULL OR fan_only = 0)"
  ).get(req.params.id);
  if (!post) {
    // Could be one of OUR outbound replies (ap_outbox), not a post.
    const note = AP.getOutboxNote(baseUrl(req), req.params.id);
    if (!note) return res.status(404).end();
    if (!AP.apWants(req)) {
      // A browser hit a reply's AP URL → send them to the source it replies to
      // (where the post + its reactions live), falling back to the site home.
      const src = (typeof note.inReplyTo === 'string' && /^https?:\/\//i.test(note.inReplyTo))
        ? note.inReplyTo : (baseUrl(req) + '/');
      return res.redirect(302, src);
    }
    return AP.sendAP(res, { '@context': AP.AP_CONTEXT, ...note });
  }
  const site = db.prepare('SELECT * FROM sites WHERE id = ?').get(post.site_id);
  if (!site) return res.status(404).end();
  const note = AP.buildNote(baseUrl(req), site, post);
  if (!AP.apWants(req)) {
    // A browser hit a post's AP note URL → send them to the human post page
    // (which shows the post + its "from the fediverse" reactions).
    return res.redirect(302, note.url || (baseUrl(req) + '/'));
  }
  AP.sendAP(res, { '@context': AP.AP_CONTEXT, ...note });
});

// ── Replies collection ── lets remote servers fetch a post's whole thread.
router.get('/ap/notes/:id/replies', (req, res) => {
  const base = baseUrl(req);
  const items = AP.getReplyUris(base, req.params.id);
  AP.sendAP(res, {
    '@context': AP.AP_CONTEXT,
    id: `${base}/ap/notes/${req.params.id}/replies`,
    type: 'OrderedCollection',
    totalItems: items.length,
    orderedItems: items,
  });
});

// ── NodeInfo ── standard instance metadata so fediverse tools recognise Klonkt.
router.get('/.well-known/nodeinfo', (req, res) => {
  res.type('application/json');
  res.set('Cache-Control', 'public, max-age=3600');
  res.send(JSON.stringify({ links: [{ rel: 'http://nodeinfo.diaspora.software/ns/schema/2.1', href: `${baseUrl(req)}/nodeinfo/2.1` }] }));
});
router.get('/nodeinfo/2.1', (req, res) => {
  let users = 0; let posts = 0;
  // "users" = public AP actors (sites), not the admin/member account rows.
  try { users = db.prepare('SELECT COUNT(*) c FROM sites WHERE (is_public IS NULL OR is_public = 1)').get().c; } catch { /* */ }
  try { posts = db.prepare("SELECT COUNT(*) c FROM posts WHERE status = 'published'").get().c; } catch { /* */ }
  res.type('application/json; charset=utf-8');
  res.set('Cache-Control', 'public, max-age=600');
  res.send(JSON.stringify({
    version: '2.1',
    software: { name: 'klonkt', version: _ver, repository: 'https://github.com/roboburr/klonkt' },
    protocols: ['activitypub'],
    services: { inbound: [], outbound: [] },
    openRegistrations: false,
    usage: { users: { total: users }, localPosts: posts },
    metadata: { nodeName: 'Klonkt' },
  }));
});

// ── Inbox — Follow→Accept, Undo Follow (best-effort signature verify) ──
const apJson = express.json({
  type: ['application/activity+json', 'application/ld+json', 'application/json'],
  limit: '1mb',
  verify: (req, _res, buf) => { req.rawBody = buf; }, // raw body for digest verification
});
router.post(['/ap/users/:slug/inbox', '/ap/inbox'], apInboxLimiter, apJson, async (req, res) => {
  try { return res.status(await AP.handleInbox(req, req.params.slug || null) || 202).end(); }
  catch (e) { console.warn('[AP inbox] error:', e.message); return res.status(202).end(); }
});

// ── Outbox POST: ActivityPub Client-to-Server ─────────────────────
// A bearer-authenticated client (Shaer) POSTs an activity; we translate it onto
// the normal delivery machinery. The token is scoped to one user+site (OAuth
// consent), so it must match the slug in the URL. (Declared after apJson, which
// this shares with the inbox handler.)
router.post('/ap/users/:slug/outbox', apInboxLimiter, apJson, async (req, res) => {
  const auth = OAuth.verifyBearer(req.headers.authorization);
  if (!auth) { res.set('WWW-Authenticate', 'Bearer'); return res.status(401).json({ error: 'invalid_token' }); }
  if (auth.site.slug !== req.params.slug) return res.status(403).json({ error: 'wrong_site', detail: 'token is scoped to a different site' });
  if (auth.user.readonly) return res.status(403).json({ error: 'read_only_account' });

  const out = await AP.ingestOutboxActivity(auth.site, auth.user, req.body);
  if (out.error) return res.status(out.status || 400).json({ error: out.error, detail: out.detail });
  // 201 Created → Location header (AP spec); 202 Accepted for side-effect verbs.
  if (out.status === 201 && out.url) res.set('Location', out.url);
  return res.status(out.status || 202).json({ ok: true, id: out.id, url: out.url });
});

export default router;