/**
 * 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/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 db from '../config/database.js';
import AP from '../services/ActivityPubService.js';

const router = express.Router();

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:([^@]+)@(.+)$/i);
  if (!m) return res.status(400).type('text/plain').send('bad resource');
  const site = publicSite(m[1]);
  if (!site) return res.status(404).end();
  res.type('application/jrd+json; charset=utf-8');
  res.set('Cache-Control', 'public, max-age=300');
  res.send(JSON.stringify({
    subject: `acct:${site.slug}@${hostOf(req)}`,
    links: [{ rel: 'self', type: 'application/activity+json', href: AP.actorId(baseUrl(req), site.slug) }],
  }));
});

// ── 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', (req, res) => {
  const site = publicSite(req.params.slug);
  if (!site) return res.status(404).end();
  const posts = db.prepare(
    `SELECT id, slug, title, content, cover_image_url, published_at, created_at
     FROM posts WHERE site_id = ? AND status = 'published' AND (fan_only IS NULL OR fan_only = 0)
     ORDER BY COALESCE(published_at, created_at) DESC LIMIT 20`
  ).all(site.id);
  AP.sendAP(res, AP.buildOutbox(baseUrl(req), site, posts));
});

// ── Followers (count only) ────────────────────────────────────────
router.get('/ap/users/:slug/followers', (req, res) => {
  const site = publicSite(req.params.slug);
  if (!site) return res.status(404).end();
  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));
});

// ── 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 AP.sendAP(res, { '@context': 'https://www.w3.org/ns/activitystreams', ...note });
    return res.status(404).end();
  }
  const site = db.prepare('SELECT * FROM sites WHERE id = ?').get(post.site_id);
  if (!site) return res.status(404).end();
  AP.sendAP(res, { '@context': 'https://www.w3.org/ns/activitystreams', ...AP.buildNote(baseUrl(req), site, post) });
});

// ── 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'], 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(); }
});

export default router;