// Audiobooks from the audiobook player (https://git.necloud.us/nate/audiobook-player) at AUDIOBOOKS_URL: the library, covers, chapters, the audio itself
// and each person's listening position. The hub signs in to the player as the person (their audiobook sign-in from Settings), or, when they have
// none saved, with the site's shared secret link (AUDIOBOOKS_LOGIN_LINK), so no password or link ever reaches the browser.
const { Readable } = require('stream');
const settings = require('./settings');
const users = require('./users');

const BASE = (process.env.AUDIOBOOKS_URL || 'https://audiobooks.necloud.us').replace(/\/$/, '');
const LINK = process.env.AUDIOBOOKS_LOGIN_LINK || '';
const COOKIE = 'oa_session';
const sessions = new Map(); // person id -> the player's session cookie
const json = (res, code, o) => { res.writeHead(code, { 'content-type': 'application/json', 'cache-control': 'no-store' }); res.end(JSON.stringify(o)); };
const cookieOf = r => { const c = (r.headers.getSetCookie ? r.headers.getSetCookie() : []).map(x => x.split(';')[0]).find(x => x.startsWith(COOKIE + '=')); return c || ''; };

// Hub path -> player path (the player itself only serves read-only calls for these)
const ROUTES = [
  [/^\/books$/, () => '/api/books'],
  [/^\/books\/([^/]+)\/(chapters\/flat|cover)$/, m => `/api/books/${m[1]}/${m[2]}`],
  [/^\/books\/([^/]+)\/filelist$/, m => `/admin/api/books/${m[1]}/files`],
  [/^\/books\/([^/]+)\/files\/([^/]+)$/, m => `/api/books/${m[1]}/files/${m[2]}`],
];

async function signIn(me) {
  const c = settings.get('ab_creds') || {};
  let r;
  if (c.u && c.p) r = await fetch(BASE + '/login', { method: 'POST', headers: { 'content-type': 'application/json' }, body: JSON.stringify({ username: c.u, password: c.p }), redirect: 'manual', signal: AbortSignal.timeout(15000) });
  else if (LINK) r = await fetch(LINK, { redirect: 'manual', signal: AbortSignal.timeout(15000) });
  else throw Object.assign(new Error('Add your audiobook sign-in in Settings first'), { code: 503 });
  const ck = cookieOf(r);
  if (!ck) throw Object.assign(new Error(c.u ? 'The audiobook site did not accept your saved sign-in' : 'The audiobook site did not accept the shared sign-in'), { code: 502 });
  sessions.set(me.id, ck); return ck;
}

async function upstream(me, path, init = {}, retry = true) {
  const ck = sessions.get(me.id) || await signIn(me);
  const r = await fetch(BASE + path, { ...init, headers: { ...init.headers, cookie: ck }, redirect: 'manual' });
  if ((r.status === 401 || r.status === 302) && retry) { sessions.delete(me.id); await r.body?.cancel().catch(() => {}); return upstream(me, path, init, false); }
  return r;
}

async function handle(req, res) {
  const me = users.current();
  const u = new URL(req.url, 'http://x'), p = u.pathname.slice('/api/ab'.length) || '/';
  const ctl = new AbortController(); res.on('close', () => ctl.abort());
  try {
    if (p === '/progress') {
      if (req.method === 'POST') {
        const chunks = []; let n = 0; for await (const c of req) { n += c.length; if (n > 1e6) return json(res, 413, { error: 'Too large' }); chunks.push(c); }
        const r = await upstream(me, '/sync/progress', { method: 'POST', body: Buffer.concat(chunks), headers: { 'content-type': 'application/json' }, signal: ctl.signal });
        res.writeHead(r.status, { 'content-type': 'application/json', 'cache-control': 'no-store' }); return res.end(Buffer.from(await r.arrayBuffer()));
      }
      if (req.method !== 'GET') return json(res, 405, { error: 'Method not allowed' });
      const r = await upstream(me, '/sync/progress', { signal: ctl.signal });
      res.writeHead(r.status, { 'content-type': 'application/json', 'cache-control': 'no-store' }); return res.end(Buffer.from(await r.arrayBuffer()));
    }
    if (req.method !== 'GET') return json(res, 405, { error: 'Method not allowed' });
    let to = null; for (const [re, f] of ROUTES) { const m = re.exec(p); if (m) { to = f(m); break; } }
    if (!to) return json(res, 404, { error: 'Not found' });
    const headers = req.headers.range ? { range: req.headers.range } : {};
    const r = await upstream(me, to, { headers, signal: ctl.signal });
    const out = { 'cache-control': p.endsWith('/cover') ? 'private, max-age=86400' : 'no-store' };
    for (const k of ['content-type', 'content-length', 'content-range', 'accept-ranges']) if (r.headers.get(k)) out[k] = r.headers.get(k);
    res.writeHead(r.status, out);
    if (!r.body) return res.end();
    Readable.fromWeb(r.body).on('error', () => res.destroy()).pipe(res);
  } catch (e) {
    if (res.headersSent) return res.destroy();
    json(res, e.code || 502, { error: e.code ? e.message : 'The audiobook site did not answer' });
  }
}

module.exports = { handle };