'use strict';
/*
 * MangaCircus: a no-frills, self-hosted manga reader. No dependencies, just `node server.js`.
 *
 * Environment:
 *   PORT=8080            LIBRARY=./library        DATA=./data
 *   SIGNUP=closed|open   (the very first account can always be created and becomes admin)
 *   SCAN_INTERVAL=10     minutes between shallow change checks, 0 = off
 *   FULL_SCAN_INTERVAL=1440  minutes between full reconciliations, 0 = off
 *   SCAN_CONCURRENCY=8   chapter folders / images probed at once by an uncached scan (library.js)
 *   COOKIE_SECURE=1      mark the session cookie Secure (when served over HTTPS)
 *   SCRAPER_URL=http://127.0.0.1:8091   scraper daemon API
 *   SCRAPER_TOKEN=...                    shared daemon token (optional on loopback)
 *   BACKUP=/backup       folder for built-in DATA backups (unset = backups off)
 */
const http = require('http'), fs = require('fs'), path = require('path'), crypto = require('crypto');
const { scanLibrary, scanChangedLibrary, libraryStamps, snapshotIndex, restoreIndex } = require('./library');
const { Catalog, CatalogError, collectionViews, TYPES, ROLES } = require('./catalog');
const { RATINGS: GREATEST_RATINGS, loadCatalog: loadGreatestCatalog, findOwned: findGreatestOwned,
  countsFor: greatestCounts, scoreFor: greatestScore } = require('./greatest');
const { hosterLinks } = require('./greatest/hosters');
const { GreatestCovers } = require('./greatest/covers');
const { secret } = require('./runtime/config');
const { PeeringState, requirePeer } = require('./peering/state');
const peerClient = require('./peering/client');
const { DiscoveryStore } = require('./discovery/store');
const { generateAsync: generateDiscovery, mergeUserFeed } = require('./discovery/engine');
const { DiscoveryCache } = require('./discovery/cache');
const { createClient: createAniListClient } = require('./discovery/anilist');
const { anchorsFor } = require('./discovery/anchors');
const { shouldRunNightly, Harvester } = require('./discovery/harvest');
const {
  applyPulse, applyVisit, chapterInsight, earliestCompletion, eligiblePages, emptyRecord, libraryInsight, mangaInsight, publicSummary,
} = require('./reading-analytics');
const { chapterDates } = require('./chapter-dates');
const { parseSchedule, publicSchedule, loadQuestionBank, createReadingAccess } = require('./reading-access');
const { BackupService, BackupError } = require('./backup');

const PORT = +process.env.PORT || 8080;
const LIB = path.resolve(process.env.LIBRARY || 'library');
const DATA = path.resolve(process.env.DATA || 'data');
const OPEN_SIGNUP = process.env.SIGNUP === 'open';
const SCAN_MINUTES = +(process.env.SCAN_INTERVAL || 10);
const FULL_SCAN_MINUTES = +(process.env.FULL_SCAN_INTERVAL || 1440);
const SECURE_COOKIE = process.env.COOKIE_SECURE === '1';
const SCRAPER_URL = String(process.env.SCRAPER_URL || 'http://127.0.0.1:8091').replace(/\/$/, '');
const SCRAPER_TOKEN = secret('SCRAPER_TOKEN');
const PEER_DATA = path.resolve(process.env.PEER_DATA || path.join(DATA, 'peering'));
const peerStore = new PeeringState(PEER_DATA);
const discoveryStore = new DiscoveryStore(DATA);
const DISCOVERY_CACHE = path.join(DATA, 'scraper', 'metadata', 'anilist');
const DISCOVERY_HARVEST_CACHE = path.join(DATA, 'discovery-cache');
const HARVEST_TIME = /^([01]\d|2[0-3]):[0-5]\d$/;
const DISCOVERY_HARVEST_AT = HARVEST_TIME.test(process.env.DISCOVERY_HARVEST_AT || '') ? process.env.DISCOVERY_HARVEST_AT : '03:30';
let discoveryRun = null, discoveryError = null;
const PUB = path.join(__dirname, 'public');
const IMG = /\.(jpe?g|png|webp|gif|avif|bmp)$/i;
const MIME = {
  '.html': 'text/html; charset=utf-8', '.js': 'text/javascript; charset=utf-8', '.css': 'text/css; charset=utf-8',
  '.json': 'application/json', '.webmanifest': 'application/manifest+json', '.svg': 'image/svg+xml', '.ico': 'image/x-icon',
  '.png': 'image/png', '.jpg': 'image/jpeg', '.jpeg': 'image/jpeg', '.webp': 'image/webp', '.gif': 'image/gif', '.avif': 'image/avif', '.bmp': 'image/bmp',
};

// ---------- storage: one JSON file, written atomically ----------
fs.mkdirSync(DATA, { recursive: true });
const catalog = new Catalog(DATA);
const greatestCatalog = loadGreatestCatalog();
const greatestById = new Map(greatestCatalog.entries.map(entry => [entry.id, entry]));
const greatestCovers = new GreatestCovers(path.join(DATA, 'greatest-covers'));
// The versioned URL lets browsers keep a cover for a year; a new catalog URL changes `v`.
const greatestCoverUrl = entry => entry.cover
  ? `api/greatest-cover?id=${encodeURIComponent(entry.id)}&v=${greatestCovers.version(entry.cover)}` : null;
const DB_FILE = path.join(DATA, 'db.json'), CACHE_FILE = path.join(DATA, 'scan-cache.json'), INDEX_FILE = path.join(DATA, 'library-index.json');
const db = { users: {}, sessions: {}, progress: {}, reading: {}, readingAccess: {}, follows: {}, notes: {}, votes: {}, greatestRatings: {}, discoveryFeedback: {}, known: {} };
// A corrupt db.json stops the server instead of silently starting empty and overwriting it.
if (fs.existsSync(DB_FILE)) Object.assign(db, JSON.parse(fs.readFileSync(DB_FILE, 'utf8')));
function writeAtomic(file, text) { fs.writeFileSync(file + '.tmp', text); fs.renameSync(file + '.tmp', file); }
let saveTimer = null;
function save() { saveTimer = saveTimer || setTimeout(flush, 500); }
function flush() { clearTimeout(saveTimer); saveTimer = null; writeAtomic(DB_FILE, JSON.stringify(db)); }
for (const sig of ['SIGINT', 'SIGTERM']) process.on(sig, () => { flush(); process.exit(0); });
db.readingAccess ||= {};
// The reader owns backups: it alone mounts all of DATA and holds db.json in memory.
const backup = new BackupService({ dataRoot: DATA, backupRoot: process.env.BACKUP || '', snapshotDb: () => JSON.stringify(db),
  scraper: { state: () => scraperRequest('/api/state'), control: action => scraperRequest('/api/control', { action }) } }).start();
const readingSchedule = parseSchedule(process.env.READING_WINDOWS_JSON || '', process.env.READING_TIMEZONE || process.env.TZ || 'Europe/Berlin');
const readingAccess = createReadingAccess({ schedule: readingSchedule,
  bank: loadQuestionBank(process.env.READING_QUIZ_CATALOG_PATH || ''),
  unlockMinutes: Number(process.env.READING_QUIZ_UNLOCK_MINUTES || 60), grants: db.readingAccess, save,
  getProgress: (user, mangaId) => db.progress[user]?.[mangaId] || {},
  getMangaTitle: mangaId => lib.byId.get(mangaId)?.title || null });

// `extra` fields are sent next to `error`, e.g. `nextAllowedAt` on a 429.
class HttpError extends Error { constructor(code, msg, extra = {}) { super(msg); this.code = code; this.extra = extra; } }
function bad(code, msg, extra) { throw new HttpError(code, msg, extra); }
function peerForRoute(id) {
  try { return requirePeer(peerStore.load(), id); }
  catch { bad(404, 'Peer not found'); }
}
async function peerRemote(task) {
  try { return await task(); }
  catch (error) { bad(502, `Peer service: ${String(error.message || error).slice(0, 300)}`); }
}

// ---------- users & sessions ----------
const sha = s => crypto.createHash('sha256').update(s).digest('hex');
function hashPw(pw) { const salt = crypto.randomBytes(16).toString('hex'); return salt + ':' + crypto.scryptSync(pw, salt, 32).toString('hex'); }
function checkPw(pw, stored) {
  const [salt, hex] = String(stored).split(':'), want = Buffer.from(hex || '', 'hex'), got = crypto.scryptSync(pw, salt || '', 32);
  return want.length === got.length && crypto.timingSafeEqual(want, got);
}
const DUMMY_HASH = hashPw('x');
const DEFAULTS = { startMode: 'last', lastMode: 'page', adapt: true, skipExtras: false, skipCovers: false, flowPageGap: true, pageTone: 'original', readingClock: false, readingStory: true,
  continueRow: true, readDate: 'hour', releaseDate: true, discoveryEnabled: false, discoveryReadingActivity: false, discoveryMature: false, zoom: {}, webhook: '' };
const settingsOf = u => ({ ...DEFAULTS, ...u.settings, zoom: { ...(u.settings && u.settings.zoom) } });

function createUser(name, pw, admin, replace) {
  name = String(name || '').trim().toLowerCase(); pw = String(pw || '');
  if (!/^[a-z0-9_.-]{1,32}$/.test(name)) bad(400, 'User names may only use a-z, 0-9, "_", "." and "-" (max. 32).');
  if (pw.length < 4) bad(400, 'The password needs at least 4 characters.');
  const old = db.users[name];
  if (old && !replace) bad(409, 'That user name is taken.');
  db.users[name] = { settings: {}, ...old, name, hash: hashPw(pw), admin: !!admin, created: old ? old.created : Date.now() };
  save();
  return db.users[name];
}
function startSession(res, user) {
  const token = crypto.randomBytes(32).toString('base64url');
  db.sessions[sha(token)] = { u: user.name, t: Date.now() };
  save();
  res.setHeader('Set-Cookie', `sid=${token}; Path=/; HttpOnly; SameSite=Lax; Max-Age=31536000${SECURE_COOKIE ? '; Secure' : ''}`);
}
const tokenOf = req => { const m = /(?:^|;\s*)sid=([^;]+)/.exec(req.headers.cookie || ''); return m ? m[1] : null; };
function userOf(req) { const t = tokenOf(req), s = t && db.sessions[sha(t)]; return (s && db.users[s.u]) || null; }
for (const [k, s] of Object.entries(db.sessions)) if (Date.now() - s.t > 365 * 864e5 || !db.users[s.u]) delete db.sessions[k];

// ---------- library index ----------
let lib = { mangas: [], byId: new Map() }, scanning = null, pendingScan = null, scanState = {}, scanCache = {}, scanStamps = {};
let lastFullAt = 0, lastFullAttemptAt = 0;
try { scanCache = JSON.parse(fs.readFileSync(CACHE_FILE, 'utf8')); } catch { /* first run */ }
try {
  const saved = JSON.parse(fs.readFileSync(INDEX_FILE, 'utf8'));
  if (saved.version !== 1 || saved.root !== LIB || !saved.cache || !saved.stamps) throw new Error('Invalid library index snapshot');
  const restored = restoreIndex(saved.mangas);
  // A disconnected/replaced library mount must not appear populated from cache.
  const present = new Set(fs.readdirSync(LIB, { withFileTypes: true }).filter(e => e.isDirectory()).map(e => e.name));
  if (restored.mangas.length && !restored.mangas.some(m => present.has(m.id))) throw new Error('Library mount differs from snapshot');
  lib = restored; scanCache = saved.cache; scanStamps = saved.stamps;
  lastFullAt = Number(saved.fullAt) || Number(saved.at) || 0;
  scanState = { at: saved.at, mode: 'snapshot', stale: true, mangas: lib.mangas.length, error: null };
  console.log(`[scan] restored ${lib.mangas.length} manga from saved index; verifying in background`);
} catch (e) { if (e.code !== 'ENOENT') console.warn(`[scan] ignoring saved index: ${e.message}`); }

async function performScan(mode) {
    const t0 = Date.now();
    try {
      // Capture before the scan: a publication during the walk remains visible
      // as a changed stamp on the next check, rather than being silently missed.
      const stamps = await libraryStamps(LIB);
      const result = mode === 'changed' && Object.keys(scanStamps).length
        ? await scanChangedLibrary(LIB, lib, scanCache, scanStamps, stamps)
        : { ...(await scanLibrary(LIB, mode === 'deep' ? {} : scanCache)), stamps, changed: Object.keys(stamps) };
      const { index, cache, changed } = result;
      if (mode !== 'changed' || changed.length) {
        announce(index);
        lib = index; scanCache = cache; scanStamps = stamps;
        if (mode !== 'changed') lastFullAt = Date.now();
        writeAtomic(CACHE_FILE, JSON.stringify(cache));
        writeAtomic(INDEX_FILE, JSON.stringify({ version: 1, root: LIB, at: Date.now(), fullAt: lastFullAt,
          mangas: snapshotIndex(index), cache, stamps }));
      }
      let chapters = 0, pages = 0;
      for (const m of lib.mangas) for (const ch of m.chapters) { chapters++; for (const v of ch.versions) pages += v.pages.length; }
      scanState = { at: Date.now(), ms: Date.now() - t0, mode, changedMangas: changed.length,
        mangas: lib.mangas.length, chapters, pages, stale: false, error: null };
      console.log(`[scan] ${mode}: ${changed.length} changed manga, ${lib.mangas.length} manga, ${chapters} chapters, ${pages} pages in ${scanState.ms} ms`);
      return scanState;
    } catch (e) {
      scanState = { ...scanState, at: Date.now(), error: e.message };
      console.error('[scan] failed:', e.message);
      return scanState;
    }
}
function queueScan(mode) {
  if (scanning) {
    const priority = { changed: 1, full: 2, deep: 3 };
    if (!pendingScan || priority[mode] > priority[pendingScan]) pendingScan = mode;
    return scanning;
  }
  scanning = (async () => {
    let next = mode, result;
    do { result = await performScan(next); next = pendingScan; pendingScan = null; } while (next);
    return result;
  })().finally(() => { scanning = null; });
  return scanning;
}
function rescan(full) { return queueScan(full ? 'deep' : 'full'); }
function refreshChanged() { return queueScan('changed'); }

// New chapter ids (compared with every id ever seen for that manga) notify the followers.
function announce(index) {
  for (const m of index.mangas) {
    const known = db.known[m.id];
    if (!known) { db.known[m.id] = m.chapters.map(c => c.id); save(); continue; }
    const seen = new Set(known), fresh = m.chapters.filter(c => !seen.has(c.id));
    if (!fresh.length) continue;
    db.known[m.id] = known.concat(fresh.map(c => c.id));
    for (const [name, follows] of Object.entries(db.follows)) if (follows[m.id] && db.users[name]) notify(db.users[name], m, fresh);
    save();
  }
}
function notify(user, m, chapters) {
  const notes = (db.notes[user.name] = db.notes[user.name] || []);
  for (const ch of chapters) {
    notes.push({ id: crypto.randomBytes(6).toString('hex'), t: Date.now(), m: m.id, c: ch.id, text: `${m.title} · ${ch.label}${ch.title ? ': ' + ch.title : ''}`, read: false });
  }
  if (notes.length > 200) notes.splice(0, notes.length - 200);
  const hook = settingsOf(user).webhook;
  if (hook) {
    const body = `New in ${m.title}: ${chapters.map(c => c.label + (c.title ? ' ' + c.title : '')).join(', ')}`;
    fetch(hook, { method: 'POST', body, headers: { 'Content-Type': 'text/plain; charset=utf-8', Title: 'MangaCircus' }, signal: AbortSignal.timeout(10000) })
      .catch(e => console.warn(`[notify] webhook of ${user.name} failed: ${e.message}`));
  }
}

// ---------- view helpers ----------
const url = rel => (rel ? 'lib/' + rel.split('/').map(encodeURIComponent).join('/') : null);
const mangaOf = id => lib.byId.get(String(id)) || bad(404, 'Manga not found');
const chapterOf = (m, id) => m.chapterById.get(String(id)) || bad(404, 'Chapter not found');
const progressOf = (u, m) => (db.progress[u.name] && db.progress[u.name][m.id]) || {};
const mangaReadingOf = (u, m) => (db.reading[u.name] && db.reading[u.name][m.id]) || {};
const readingOf = (u, m, ch) => (db.reading[u.name] && db.reading[u.name][m.id] && db.reading[u.name][m.id][ch.id]) || null;
const unreadOf = u => (db.notes[u.name] || []).filter(n => !n.read).length;
const admin = u => u.admin || bad(403, 'Admins only');
const READING_LEASE_MS = 15000;
const readingLeases = new Map();

async function scraperRequest(endpoint, body) {
  const headers = { accept: 'application/json' };
  if (SCRAPER_TOKEN) headers.authorization = `Bearer ${SCRAPER_TOKEN}`;
  const options = { headers, signal: AbortSignal.timeout(7000) };
  if (body !== undefined) {
    options.method = 'POST'; headers['content-type'] = 'application/json'; options.body = JSON.stringify(body);
  }
  let response;
  try { response = await fetch(SCRAPER_URL + endpoint, options); }
  catch (error) { throw new HttpError(503, `Scraper service unavailable: ${error.message}`); }
  const data = await response.json().catch(() => ({}));
  if (!response.ok) throw new HttpError(response.status >= 500 ? 502 : response.status, data.error || `Scraper HTTP ${response.status}`);
  return data;
}

function readDiscovery() {
  try { return discoveryStore.load(); }
  catch (error) { bad(503, error.message); }
}
// Scoring is local: it reads the harvest cache and never calls AniList. With `onlyUser` only that
// feed is rebuilt and the other users' feeds are carried over into the same publish.
async function rescoreNow(onlyUser) {
  const startedAt = new Date().toISOString();
  let queuedTitles = [], queueAvailable = true;
  try { queuedTitles = (await scraperRequest('/api/state')).queue?.filter(item => !['complete', 'removed'].includes(item.status)).map(item => item.title) || []; }
  catch { queueAvailable = false; }
  const result = await generateDiscovery({ db, library: lib.mangas, greatest: greatestCatalog,
    cacheDir: DISCOVERY_CACHE, harvestCache, queuedTitles, onlyUser });
  // Read the prior store only now, right before the synchronous publish, so no other publish slips between.
  const value = onlyUser === undefined ? result : { ...result, ...mergeUserFeed(discoveryStore.load(), result, onlyUser) };
  return { published: discoveryStore.publish({ ...value, startedAt }), queueAvailable };
}
// One rescore at a time: an admin run and a harvest follow-up must not publish over each other.
let rescoring = Promise.resolve();
function rescore({ onlyUser } = {}) {
  const run = rescoring.then(() => rescoreNow(onlyUser));
  rescoring = run.catch(() => {});
  return run;
}
function startDiscoveryRun() {
  if (discoveryRun?.status === 'running') bad(409, 'A discovery run is already active');
  readDiscovery(); // Refuse a new run if the on-disk store is corrupt.
  const id = crypto.randomUUID(), startedAt = new Date().toISOString();
  discoveryRun = { id, status: 'running', startedAt };
  discoveryError = null;
  setImmediate(async () => {
    try {
      const { published, queueAvailable } = await rescore();
      discoveryRun = { id, status: 'success', startedAt, finishedAt: published.lastRun.finishedAt,
        candidates: published.lastRun.candidateCount, queueAvailable };
    } catch (error) {
      discoveryError = String(error.message || error).slice(0, 300);
      discoveryRun = { id, status: 'failed', startedAt, finishedAt: new Date().toISOString() };
      console.error('[discovery]', discoveryError);
    }
  });
  return discoveryRun;
}

// ---------- discovery harvest (AniList seeds, BL-0051) ----------
const harvestCache = new DiscoveryCache(DISCOVERY_HARVEST_CACHE);
const discoverySettings = state => ({ harvestEnabled: state.settings?.harvestEnabled ?? true,
  harvestAt: state.settings?.harvestAt ?? DISCOVERY_HARVEST_AT });
const localDate = date => [date.getFullYear(), String(date.getMonth() + 1).padStart(2, '0'), String(date.getDate()).padStart(2, '0')].join('-');
function nextNightlyAt(state, now = new Date()) {
  const { harvestEnabled, harvestAt } = discoverySettings(state);
  if (!harvestEnabled) return null;
  const [hours, minutes] = harvestAt.split(':').map(Number);
  const slot = new Date(now);
  slot.setHours(hours, minutes, 0, 0);
  if (state.nightly?.lastDate === localDate(now)) slot.setDate(slot.getDate() + 1);
  else if (slot < now) return now.toISOString(); // due: the next minute's check starts it
  return slot.toISOString();
}
function harvestTargets(kind, userName) {
  const users = kind === 'user' ? [db.users[userName]].filter(Boolean) : Object.values(db.users);
  return users.filter(user => settingsOf(user).discoveryEnabled).map(user => ({ user,
    anchors: anchorsFor({ user, db, library: lib.mangas, greatest: greatestCatalog }), mature: !!settingsOf(user).discoveryMature }));
}
// Queued jobs live in memory only; a run cut off by a restart is recorded as interrupted.
try {
  const { harvest } = discoveryStore.load();
  if (harvest?.status === 'running') discoveryStore.patch({ harvest: { ...harvest, status: 'interrupted', finishedAt: new Date().toISOString() } });
} catch (error) { console.error('[discovery]', error.message); }
const harvester = new Harvester({ cache: harvestCache, client: createAniListClient(), store: discoveryStore,
  targetsFor: harvestTargets, onDone: async job => {
    // A failed follow-up rescore must reach the admin panel (lastError), not only the log.
    try {
      await rescore(job.kind === 'user' ? { onlyUser: job.user } : {});
      discoveryError = null; // a later success must not leave an old failure on the admin panel
    } catch (error) { discoveryError = `Re-scoring after harvest ${job.id} failed: ${String(error.message || error)}`.slice(0, 300); throw error; }
  } });
function requestHarvest(args) {
  readDiscovery(); // A corrupt store fails closed before any AniList call.
  try { return harvester.request(args); }
  catch (error) {
    if (!error.status) throw error;
    const extra = {};
    for (const key of ['nextAllowedAt', 'blockedReason']) if (error[key]) extra[key] = error[key];
    bad(error.status, error.message, extra);
  }
}
function checkNightly() {
  let state;
  try { state = discoveryStore.load(); } catch { return; }
  const now = new Date(), { harvestEnabled, harvestAt } = discoverySettings(state);
  if (!shouldRunNightly({ now, harvestAt, lastNightlyDate: state.nightly?.lastDate, enabled: harvestEnabled })) return;
  if (harvester.current()) return;
  // The date is written only once the run was accepted; a 409 (refresh in flight) retries next minute.
  try { harvester.request({ kind: 'nightly' }); }
  catch (error) { if (error.status !== 409) console.error('[discovery] nightly harvest:', error.message); return; }
  try { discoveryStore.patch({ nightly: { lastDate: localDate(now) } }); }
  catch (error) { console.error('[discovery]', error.message); }
}

const mangaDexSearchCache = new Map();
let lastMangaDexSearch = 0;
async function searchGreatestMangaDex(entry) {
  const cached = mangaDexSearchCache.get(entry.id);
  if (cached && Date.now() - cached.time < 60 * 60 * 1000) return cached.results;
  if (Date.now() - lastMangaDexSearch < 2000) bad(429, 'Wait two seconds before another MangaDex lookup');
  lastMangaDexSearch = Date.now();
  let response;
  try {
    response = await fetch(`https://api.mangadex.org/manga?title=${encodeURIComponent(entry.title)}&limit=10`,
      { headers: { accept: 'application/json' }, signal: AbortSignal.timeout(7000) });
  } catch (error) { throw new HttpError(503, `MangaDex lookup unavailable: ${error.message}`); }
  if (!response.ok) throw new HttpError(response.status === 429 ? 503 : 502, `MangaDex lookup returned HTTP ${response.status}`);
  const body = await response.json();
  const results = (body.data || []).filter(row => /^[0-9a-f-]{36}$/i.test(row.id)).map(row => ({
    title: row.attributes?.title?.en || Object.values(row.attributes?.title || {})[0] || 'Untitled',
    year: row.attributes?.year || null, url: `https://mangadex.org/title/${row.id}`,
  }));
  mangaDexSearchCache.set(entry.id, { time: Date.now(), results });
  return results;
}

// Versions sorted by the sum of all user votes; ties go to the higher "priority" in chapter.json, then folder order.
function ranked(m, ch) {
  const votes = (db.votes[m.id] && db.votes[m.id][ch.id]) || {};
  return ch.versions
    .map((v, i) => ({ v, i, score: Object.values(votes[v.id] || {}).reduce((a, b) => a + b, 0) }))
    .sort((a, b) => b.score - a.score || (+b.v.meta.priority || 0) - (+a.v.meta.priority || 0) || a.i - b.i);
}
function versionsOf(m, ch, u) {
  const votes = (db.votes[m.id] && db.votes[m.id][ch.id]) || {};
  return ranked(m, ch).map(({ v, score }) => ({
    id: v.id, source: v.source, sourceUrl: v.sourceUrl, pages: v.pages.length, added: v.added, score, my: (votes[v.id] && votes[v.id][u.name]) || 0,
  }));
}

// Normalize the release-date shapes accepted by manga.json for library sorting.
function firstReleaseOf(meta) {
  meta = meta || {};
  const raw = meta.firstReleaseDate || meta.releaseDate || meta.startDate;
  let year, month, day, label, time;
  if (raw && typeof raw === 'object') {
    year = +raw.year; month = +raw.month || 1; day = +raw.day || 1;
    if (year > 0) {
      label = [String(year).padStart(4, '0'), raw.month ? String(month).padStart(2, '0') : null, raw.day ? String(day).padStart(2, '0') : null].filter(Boolean).join('-');
      time = Date.UTC(year, month - 1, day);
    }
  } else if (typeof raw === 'string' && raw.trim()) {
    const parsed = Date.parse(raw);
    if (Number.isFinite(parsed)) { label = raw.trim(); time = parsed; }
  }
  if (!Number.isFinite(time)) {
    year = +meta.year;
    if (year > 0) { label = String(year); time = Date.UTC(year, 0, 1); }
  }
  return { label: label || '', time: Number.isFinite(time) ? time : 0 };
}
// When a done chapter was completed: the progress record, or for reads saved before doneAt
// existed, the earliest completion the reading clock still remembers.
function readAtOf(progress, record) {
  if (!progress || !progress.done) return null;
  if (progress.doneAt) return { at: progress.doneAt, approx: false };
  return earliestCompletion(record);
}
function continueOf(m, prog, s) {
  const ok = c => !(s.skipExtras && c.extra);
  let last = null;
  for (const ch of m.chapters) { const p = prog[ch.id]; if (p && (!last || p.t > last.p.t)) last = { ch, p }; }
  if (!last) { const first = m.chapters.find(ok) || m.chapters[0]; return { c: first.id, text: 'Start reading · ' + first.label }; }
  if (!last.p.done) return { c: last.ch.id, v: last.p.v, text: `Continue · ${last.ch.label} · page ${last.p.p + 1}` };
  const next = m.chapters.slice(m.chapters.indexOf(last.ch) + 1).find(ok);
  return next ? { c: next.id, text: 'Read next · ' + next.label } : { c: last.ch.id, v: last.p.v, text: 'Read again · ' + last.ch.label };
}
function neighbour(m, ch, step, s) {
  for (let i = m.chapters.indexOf(ch) + step; i >= 0 && i < m.chapters.length; i += step) {
    const c = m.chapters[i];
    if (!(s.skipExtras && c.extra)) return { id: c.id, label: c.label, title: c.title };
  }
  return null;
}

// ---------- API ----------
const PUBLIC = new Set(['/api/auth', '/api/login', '/api/signup']);
const routes = {
  'GET /api/health': () => ({ ok: !scanState.error, service: 'reader', uptime: Math.round(process.uptime()), scan: scanState }),
  'GET /api/collections': ({ u }) => ({ collections: routes['GET /api/library']({ u }).collections }),
  'GET /api/collection': ({ u, q }) => {
    const view = routes['GET /api/library']({ u }).collections.find(c => c.id === q.get('id')) || bad(404, 'Collection not found');
    const next = view.members.find(m => m.read < m.chapters) || view.members[0];
    const manga = mangaOf(next.id);
    return { ...view, continue: { m: next.id, ...continueOf(manga, progressOf(u, manga), settingsOf(u)) },
      relations: catalog.state.relations.filter(r => r.state === 'confirmed' && view.members.some(m => m.id === r.from || m.id === r.to)) };
  },
  'GET /api/admin/catalog': ({ u }) => { admin(u); return { ...catalog.state, types: TYPES, roles: ROLES, mangas: lib.mangas.map(m => ({ id: m.id, title: m.title })) }; },
  'POST /api/admin/catalog': ({ u, b }) => { admin(u); return catalog.update(b, new Set(lib.byId.keys()), u.name); },
  'POST /api/admin/catalog/suggest': ({ u, b }) => {
    admin(u);
    return catalog.update({ ...catalog.state, revision: b.revision, relations: catalog.suggest(lib.mangas) }, new Set(lib.byId.keys()), u.name);
  },
  'POST /api/admin/catalog/research': async ({ u, b }) => {
    admin(u);
    const m = mangaOf(b.m), id = m.meta?.['x-anilist']?.id;
    if (!id) bad(400, 'Assign a verified AniList identity first');
    const { lookupAniListById } = require('./scraper/metadata/anilist');
    const meta = await lookupAniListById(id, { cacheDir: path.join(DATA, 'metadata', 'anilist') });
    const enriched = lib.mangas.map(item => item.id === m.id ? { ...item, meta } : item);
    return catalog.update({ ...catalog.state, revision: b.revision, relations: catalog.suggest(enriched) }, new Set(lib.byId.keys()), u.name);
  },
  'POST /api/admin/collection-cover': ({ u, b }) => {
    admin(u);
    const c = catalog.state.collections.find(c => c.id === b.id) || bad(404, 'Collection not found');
    if (b.revision !== catalog.state.revision) bad(409, 'Catalog changed; reload before saving');
    const image = Buffer.from(String(b.base64 || ''), 'base64');
    const ext = require('./scraper/lib/images').imageExtension(image);
    if (!ext || image.length > 600000) bad(400, 'Use a JPG, PNG, WebP, GIF, AVIF or BMP under 600 KB');
    const name = sha(image) + '.' + ext;
    const dir = path.join(DATA, 'collection-covers'); fs.mkdirSync(dir, { recursive: true });
    if (!fs.existsSync(path.join(dir, name))) fs.writeFileSync(path.join(dir, name), image, { flag: 'wx' });
    return catalog.update({ ...catalog.state, collections: catalog.state.collections.map(item => item.id === c.id ? { ...item, coverMode: 'custom', customCover: name } : item) }, new Set(lib.byId.keys()), u.name);
  },
  'GET /api/admin/health': async ({ u }) => {
    admin(u);
    return { reader: { ok: !scanState.error, uptime: Math.round(process.uptime()), scan: scanState }, backup: backup.publicState() };
  },
  'GET /api/admin/backup': ({ u }) => { admin(u); return backup.publicState(); },
  'POST /api/admin/backup': ({ u, b }) => {
    admin(u);
    try {
      if (b.command === 'settings') return backup.updateSettings(b.settings);
      if (b.command !== 'run') bad(400, 'Unknown backup command');
      if (!backup.backupRoot) bad(409, 'Backups are off: set BACKUP to a mounted folder');
      if (backup.running) bad(409, 'A backup is already running');
      backup.run('manual').catch(() => {}); // the result lands in last/history
      return backup.publicState();
    } catch (e) { if (e instanceof BackupError) bad(e.code, e.message); throw e; }
  },
  'GET /api/auth': () => ({ firstRun: !Object.keys(db.users).length, signup: OPEN_SIGNUP }),

  'POST /api/signup': ({ b, res }) => {
    const first = !Object.keys(db.users).length;
    if (!first && !OPEN_SIGNUP) bad(403, 'Sign-up is closed. Ask an admin for an account.');
    startSession(res, createUser(b.name, b.password, first));
    return { ok: true };
  },
  'POST /api/login': ({ b, res }) => {
    const user = db.users[String(b.name || '').trim().toLowerCase()], pw = String(b.password || '');
    if (!checkPw(pw, user ? user.hash : DUMMY_HASH) || !user) bad(403, 'Wrong user name or password.');
    startSession(res, user);
    return { ok: true };
  },
  'POST /api/logout': ({ req, res }) => {
    delete db.sessions[sha(tokenOf(req))];
    save();
    res.setHeader('Set-Cookie', 'sid=; Path=/; HttpOnly; SameSite=Lax; Max-Age=0');
    return { ok: true };
  },
  'GET /api/me': ({ u }) => ({ name: u.name, admin: !!u.admin, settings: settingsOf(u), unread: unreadOf(u) }),

  'GET /api/reading-schedule': () => publicSchedule(readingSchedule),
  'GET /api/reading-access': ({ u, q }) => { mangaOf(q.get('m')); return readingAccess.status(u.name, true); },
  'POST /api/reading-quiz/start': ({ u, b }) => {
    try { return readingAccess.start(u.name); }
    catch (e) { bad(409, e.message); }
  },
  'POST /api/reading-quiz/answer': ({ u, b }) => {
    try { return readingAccess.answer(u.name, String(b.challenge || ''), String(b.answer || '')); }
    catch (e) { bad(409, e.message); }
  },
  'POST /api/reading-quiz/abandon': ({ u, b }) => {
    readingAccess.abandon(u.name, String(b.challenge || ''));
    return { ok: true };
  },

  'POST /api/settings': ({ u, b }) => {
    if (typeof b.webhook === 'string' && b.webhook.trim() && !/^https?:\/\/\S+$/i.test(b.webhook.trim())) bad(400, 'The webhook must be an http(s) URL.');
    const s = (u.settings = u.settings || {});
    if (['last', 'flow', 'page', 'book'].includes(b.startMode)) s.startMode = b.startMode;
    if (['flow', 'page', 'book'].includes(b.lastMode)) s.lastMode = b.lastMode;
    if (['original', 'inverted', 'sepia', 'dim', 'extra-dim'].includes(b.pageTone)) s.pageTone = b.pageTone;
    if (['off', 'date', 'hour'].includes(b.readDate)) s.readDate = b.readDate;
    for (const k of ['adapt', 'skipExtras', 'skipCovers', 'flowPageGap', 'readingClock', 'readingStory', 'releaseDate', 'continueRow',
      'discoveryEnabled', 'discoveryReadingActivity', 'discoveryMature']) if (typeof b[k] === 'boolean') s[k] = b[k];
    if (b.zoom && typeof b.zoom === 'object') {
      s.zoom = {};
      for (const k of ['flow', 'page', 'book', 'strip']) if (+b.zoom[k] > 0) s.zoom[k] = Math.min(8, Math.max(0.1, +b.zoom[k]));
    }
    if (typeof b.webhook === 'string') s.webhook = b.webhook.trim().slice(0, 500);
    save();
    return { settings: settingsOf(u) };
  },
  'POST /api/password': ({ u, b }) => {
    if (!checkPw(String(b.old || ''), u.hash)) bad(403, 'The current password is wrong.');
    createUser(u.name, b.new, u.admin, true);
    return { ok: true };
  },

  'GET /api/library': ({ u }) => {
    const prog = db.progress[u.name] || {}, fol = db.follows[u.name] || {}, notes = (db.notes[u.name] || []).filter(n => !n.read);
    const showStory = settingsOf(u).readingStory;
    const mangas = lib.mangas.map(m => {
      const p = prog[m.id] || {}, meta = m.meta || {}, release = firstReleaseOf(meta);
      return {
        id: m.id, title: m.title, cover: url(m.cover), direction: m.direction, chapters: m.chapters.length, updated: m.updated,
        altTitles: Array.isArray(meta.altTitles) ? meta.altTitles : (meta.altTitles ? [String(meta.altTitles)] : []),
        authors: Array.isArray(meta.authors) ? meta.authors : (meta.authors ? [String(meta.authors)] : []),
        tags: Array.isArray(meta.tags) ? meta.tags : (meta.tags ? [String(meta.tags)] : []), status: meta.status || '', year: meta.year || '',
        firstRelease: release.label, firstReleaseAt: release.time,
        read: m.chapters.filter(c => p[c.id] && p[c.id].done).length,
        lastRead: Object.values(p).reduce((t, x) => Math.max(t, x.t || 0), 0),
        following: !!fol[m.id], unread: notes.filter(n => n.m === m.id).length,
        reading: showStory ? mangaInsight(mangaReadingOf(u, m), m.chapters.map(ch => ch.id)) : null,
      };
    });
    return {
      scanning: !!scanning && !lib.mangas.length,
      reading: showStory ? libraryInsight(mangas) : null,
      mangas,
      collections: collectionViews(catalog.state, mangas),
    };
  },

  'GET /api/discovery': ({ u }) => {
    const state = readDiscovery(), enabled = !!settingsOf(u).discoveryEnabled;
    const feed = enabled ? state.feeds[u.name] || null : null;
    return { enabled, settings: { discoveryEnabled: enabled,
      discoveryReadingActivity: !!settingsOf(u).discoveryReadingActivity,
      discoveryMature: !!settingsOf(u).discoveryMature },
    generatedAt: feed?.generatedAt || null, revision: state.revision, lastRun: state.lastRun,
    refresh: harvester.state(u.name),
    feedback: db.discoveryFeedback?.[u.name] || {},
    items: (feed?.items || []).map(item => ({ ...item, candidate: state.candidates[item.candidateId] || null })).filter(item => item.candidate) };
  },
  'POST /api/discovery/feedback': ({ u, b }) => {
    if (!settingsOf(u).discoveryEnabled) bad(403, 'Enable personalized discovery first');
    const id = String(b.candidateId || ''), value = b.value === null ? null : String(b.value || '');
    if (!readDiscovery().candidates[id]) bad(404, 'Discovery candidate not found');
    if (value !== null && !['interested', 'maybe', 'dismissed', 'hidden'].includes(value)) bad(400, 'Unknown feedback');
    const mine = (db.discoveryFeedback ||= {})[u.name] ||= {};
    if (value === null) delete mine[id]; else mine[id] = value;
    save();
    return { candidateId: id, value };
  },
  'POST /api/discovery/refresh': ({ u }) => {
    if (!settingsOf(u).discoveryEnabled) bad(403, 'Enable personalized discovery first');
    return requestHarvest({ kind: 'user', user: u.name });
  },
  'GET /api/admin/discovery': ({ u }) => {
    admin(u);
    const state = readDiscovery();
    return { revision: state.revision, lastRun: state.lastRun, currentRun: discoveryRun,
      lastError: discoveryError, optedInUsers: Object.values(db.users).filter(user => user.settings?.discoveryEnabled).length,
      candidateCount: Object.keys(state.candidates).length,
      harvest: state.harvest, currentHarvest: harvester.current(), cache: harvestCache.stats(),
      settings: discoverySettings(state), nextNightlyAt: nextNightlyAt(state) };
  },
  'POST /api/admin/discovery/run': ({ u }) => { admin(u); return startDiscoveryRun(); },
  'POST /api/admin/discovery/harvest': ({ u }) => { admin(u); return requestHarvest({ kind: 'admin' }); },
  'POST /api/admin/discovery/settings': ({ u, b }) => {
    admin(u);
    const keys = b && typeof b === 'object' && !Array.isArray(b) ? Object.keys(b).sort().join() : '';
    if (keys !== 'harvestAt,harvestEnabled' || typeof b.harvestEnabled !== 'boolean' || typeof b.harvestAt !== 'string' || !HARVEST_TIME.test(b.harvestAt))
      bad(400, 'Send exactly { harvestEnabled: true|false, harvestAt: "HH:MM" }');
    readDiscovery();
    const state = discoveryStore.patch({ settings: { harvestEnabled: b.harvestEnabled, harvestAt: b.harvestAt } });
    return { settings: discoverySettings(state), nextNightlyAt: nextNightlyAt(state) };
  },

  'GET /api/greatest': ({ u }) => ({
    title: greatestCatalog.title, updatedAt: greatestCatalog.updatedAt, periods: greatestCatalog.periods,
    ratings: GREATEST_RATINGS,
    entries: greatestCatalog.entries.map(entry => {
      const owned = findGreatestOwned(entry, lib.mangas);
      const counts = greatestCounts(entry.id, db.greatestRatings || {}, db.users);
      return {
        ...entry,
        cover: owned?.cover ? url(owned.cover) : greatestCoverUrl(entry),
        chapters: owned ? owned.chapters.length : entry.chapters,
        status: owned?.meta?.status || entry.status,
        library: owned ? { id: owned.id, chapters: owned.chapters.length } : null,
        hosters: hosterLinks(entry, owned).links,
        myRating: db.greatestRatings?.[u.name]?.[entry.id] || null,
        votes: counts, score: greatestScore(counts),
      };
    }),
  }),
  'POST /api/greatest/rating': ({ u, b }) => {
    const id = String(b.id || '');
    if (!greatestById.has(id)) bad(404, 'Catalog entry not found');
    const rating = b.rating === null || b.rating === '' ? null : String(b.rating || '');
    if (rating !== null && !GREATEST_RATINGS.includes(rating)) bad(400, 'Unknown rating');
    const all = (db.greatestRatings = db.greatestRatings || {});
    const mine = (all[u.name] = all[u.name] || {});
    if (rating === null) delete mine[id]; else mine[id] = rating;
    save();
    const votes = greatestCounts(id, all, db.users);
    return { id, myRating: rating, votes, score: greatestScore(votes) };
  },
  'GET /api/greatest/sources': async ({ u, q }) => {
    admin(u);
    const entry = greatestById.get(String(q.get('id') || ''));
    if (!entry) bad(404, 'Catalog entry not found');
    const owned = findGreatestOwned(entry, lib.mangas);
    try {
      const state = await scraperRequest('/api/state');
      return { available: true, ...hosterLinks(entry, owned, state.queue || []) };
    } catch (error) {
      return { available: false, error: error.message, ...hosterLinks(entry, owned) };
    }
  },
  'GET /api/greatest/mangadex-search': async ({ u, q }) => {
    admin(u);
    const entry = greatestById.get(String(q.get('id') || ''));
    if (!entry) bad(404, 'Catalog entry not found');
    return { results: await searchGreatestMangaDex(entry) };
  },

  'GET /api/manga': ({ u, q }) => {
    const m = mangaOf(q.get('m')), prog = progressOf(u, m), s = settingsOf(u), showStory = s.readingStory;
    const records = mangaReadingOf(u, m);
    return {
      chapterDates: { read: s.readDate, release: s.releaseDate },
      id: m.id, title: m.title, meta: m.meta, cover: url(m.cover), direction: m.direction,
      collections: catalog.state.collections.filter(c => c.members.some(member => member.mangaId === m.id)).map(c => ({ id: c.id, title: c.title })),
      relations: catalog.state.relations.filter(r => r.state === 'confirmed' && (r.from === m.id || r.to === m.id)).map(r => ({ ...r,
        otherId: r.from === m.id ? r.to : r.from, otherTitle: lib.byId.get(r.from === m.id ? r.to : r.from)?.title || (r.from === m.id ? r.to : r.from) })),
      following: !!(db.follows[u.name] && db.follows[u.name][m.id]),
      books: m.books.map(b => ({ key: b.key, label: b.label, title: b.title, extra: b.extra })),
      chapters: m.chapters.map(ch => ({
        id: ch.id, book: ch.book, label: ch.label, title: ch.title, extra: ch.extra, progress: prog[ch.id] || null, versions: versionsOf(m, ch, u),
        reading: showStory ? chapterInsight(records[ch.id]) : null,
        readAt: s.readDate === 'off' ? null : readAtOf(prog[ch.id], records[ch.id]),
        dates: s.releaseDate ? chapterDates(ch.versions) : null,
      })),
      reading: showStory ? mangaInsight(records, m.chapters.map(ch => ch.id)) : null,
      continue: continueOf(m, prog, settingsOf(u)),
    };
  },

  'GET /api/reading/export': ({ u }) => {
    const byManga = db.reading[u.name] || {};
    const mangas = Object.entries(byManga).map(([id, records]) => {
      const m = lib.byId.get(id), chapterIds = m ? m.chapters.map(ch => ch.id) : Object.keys(records || {});
      const chapterMap = m ? m.chapterById : new Map();
      return {
        id, title: m ? m.title : id,
        reading: mangaInsight(records, chapterIds),
        chapters: chapterIds.map(chapterId => {
          const chapter = chapterMap.get(chapterId), reading = chapterInsight(records && records[chapterId]);
          return reading ? { id: chapterId, label: chapter ? chapter.label : chapterId, title: chapter ? chapter.title : '', reading } : null;
        }).filter(Boolean),
      };
    }).filter(item => item.reading.timedChapters || item.reading.completedPasses);
    return {
      schema: 1,
      exportedAt: new Date().toISOString(),
      user: u.name,
      reading: libraryInsight(mangas),
      mangas,
    };
  },

  'POST /api/reading/delete': ({ u, b }) => {
    if (b.all) {
      if (!checkPw(String(b.password || ''), u.hash)) bad(403, 'The current password is wrong.');
      delete db.reading[u.name];
      readingLeases.delete(u.name);
      save();
      return { ok: true, deleted: 'all' };
    }
    const m = mangaOf(b.m), all = db.reading[u.name];
    if (all) delete all[m.id];
    save();
    return { ok: true, deleted: m.id };
  },

  'GET /api/chapter': ({ u, q }) => {
    const m = mangaOf(q.get('m')), ch = chapterOf(m, q.get('c')), s = settingsOf(u), prog = progressOf(u, m);
    if (!readingAccess.status(u.name).allowed) bad(423, 'Reading is outside the deployment schedule. Complete the five-question challenge to unlock it.');
    const v = ch.versions.find(x => x.id === q.get('v')) || ranked(m, ch)[0].v;
    // Opening a chapter clears its "new chapter" notification.
    let seen = false;
    for (const n of db.notes[u.name] || []) if (!n.read && n.m === m.id && n.c === ch.id) seen = n.read = true;
    if (seen) save();
    return {
      manga: { id: m.id, title: m.title },
      chapter: { id: ch.id, label: ch.label, title: ch.title, extra: ch.extra },
      version: v.id, versions: versionsOf(m, ch, u), direction: v.direction,
      pages: v.pages.map(p => ({ u: url(v.rel + '/' + p.f), w: p.w, h: p.h, t: p.t, r: p.r })),
      prev: neighbour(m, ch, -1, s), next: neighbour(m, ch, 1, s),
      progress: prog[ch.id] || null,
      reading: s.readingClock ? publicSummary(readingOf(u, m, ch), v.id, eligiblePages(v, s)) : null,
      // for the chapter picker: the whole manga across all books
      books: m.books.map(b => ({ key: b.key, label: b.label, title: b.title })),
      chapters: m.chapters.map(c => ({ id: c.id, book: c.book, label: c.label, title: c.title, extra: c.extra, done: !!(prog[c.id] && prog[c.id].done) })),
    };
  },

  'POST /api/progress': ({ u, b }) => {
    const m = mangaOf(b.m), ch = chapterOf(m, b.c);
    const all = (db.progress[u.name] = db.progress[u.name] || {}), mp = (all[m.id] = all[m.id] || {}), old = mp[ch.id] || {};
    const now = Date.now(), done = !!(old.done || b.done);
    // doneAt: when the chapter was first completed; kept until it is marked unread.
    const doneAt = old.done ? old.doneAt : done ? now : undefined;
    mp[ch.id] = {
      v: String(b.v || ''), p: Math.max(0, b.p | 0), n: Math.max(0, b.n | 0), t: now, done, ...(doneAt ? { doneAt } : {}),
      shift: Array.isArray(b.shift) ? b.shift.filter(Number.isInteger).slice(0, 1000) : old.shift || [],
    };
    save();
    return { ok: true };
  },
  // Separate endpoint: an older server on rollback cannot misread cumulative
  // visit totals as legacy deltas. Old open tabs retain their original protocol.
  'POST /api/reading/visit': context => routes['POST /api/reading/pulse']({ ...context, cumulative: true }),
  'POST /api/reading/pulse': ({ u, b, cumulative = false }) => {
    const settings = settingsOf(u);
    if (!settings.readingClock) bad(403, 'The Active Reading Clock is disabled.');
    const m = mangaOf(b.m), ch = chapterOf(m, b.c);
    const v = ch.versions.find(x => x.id === b.v) || bad(404, 'Version not found');
    const session = String(b.session || '');
    const seq = Number(b.seq);
    if (!/^[a-zA-Z0-9_-]{8,80}$/.test(session)) bad(400, 'Invalid reading session.');
    if (!Number.isInteger(seq) || seq < 1 || seq > 1e9) bad(400, 'Invalid reading pulse sequence.');

    const now = Date.now(), eligible = eligiblePages(v, settings), lease = readingLeases.get(u.name);
    const previous = readingOf(u, m, ch)?.recentSessions?.find(item => item.id === session);
    // A stale request must not reclaim a lease after a newer exit save. Final
    // snapshots can also arrive before the initial claim: do not lose that visit.
    if (cumulative && previous && seq <= previous.seq) return {
      accepted: true, duplicate: true, leaseMs: 0,
      reading: publicSummary(readingOf(u, m, ch), v.id, eligible),
    };
    const lateFinal = cumulative && b.final;
    if (!lateFinal && lease && lease.session !== session && now - lease.at < READING_LEASE_MS) {
      return {
        accepted: false,
        reason: 'other-tab',
        retryAfterMs: READING_LEASE_MS - (now - lease.at),
        reading: publicSummary(readingOf(u, m, ch), v.id, eligible),
      };
    }
    if (!lateFinal) readingLeases.set(u.name, { session, at: now });

    const byUser = (db.reading[u.name] = db.reading[u.name] || {});
    const byManga = (byUser[m.id] = byUser[m.id] || {});
    const record = (byManga[ch.id] = readingOf(u, m, ch) || emptyRecord());
    const result = (cumulative ? applyVisit : applyPulse)(record, b, { version: v.id, pageCount: v.pages.length, eligible, now });
    if (b.release && readingLeases.get(u.name)?.session === session) readingLeases.delete(u.name);
    if (!result.duplicate) save();
    return {
      accepted: true,
      duplicate: result.duplicate,
      leaseMs: b.release ? 0 : READING_LEASE_MS,
      reading: publicSummary(record, v.id, eligible),
    };
  },
  'POST /api/unread': ({ u, b }) => {
    const m = mangaOf(b.m), mp = db.progress[u.name] && db.progress[u.name][m.id];
    if (mp) delete mp[chapterOf(m, b.c).id];
    save();
    return { ok: true };
  },
  'POST /api/vote': ({ u, b }) => {
    const m = mangaOf(b.m), ch = chapterOf(m, b.c), v = ch.versions.find(x => x.id === b.v) || bad(404, 'Version not found');
    const byChapter = (db.votes[m.id] = db.votes[m.id] || {}), byVersion = (byChapter[ch.id] = byChapter[ch.id] || {});
    const votes = (byVersion[v.id] = byVersion[v.id] || {}), value = Math.sign(+b.value || 0);
    if (value) votes[u.name] = value;
    else delete votes[u.name];
    save();
    return { versions: versionsOf(m, ch, u) };
  },
  'POST /api/follow': ({ u, b }) => {
    const m = mangaOf(b.m), f = (db.follows[u.name] = db.follows[u.name] || {});
    if (b.on) f[m.id] = true;
    else delete f[m.id];
    save();
    return { following: !!f[m.id] };
  },
  'GET /api/notifications': ({ u }) => ({ items: (db.notes[u.name] || []).slice().reverse() }),
  'POST /api/notifications/read': ({ u, b }) => {
    for (const n of db.notes[u.name] || []) if (b.all || n.id === b.id) n.read = true;
    save();
    return { unread: unreadOf(u) };
  },

  'GET /api/admin': ({ u }) => {
    admin(u);
    return { users: Object.values(db.users).map(x => ({ name: x.name, admin: !!x.admin, created: x.created })), scan: { ...scanState, running: !!scanning, library: LIB } };
  },
  'POST /api/admin/rescan': async ({ u, b }) => {
    admin(u);
    await rescan(!!b.full);
    return { scan: { ...scanState, running: false, library: LIB } };
  },
  'POST /api/admin/user': ({ u, b }) => {
    admin(u);
    const name = String(b.name || '').trim().toLowerCase();
    createUser(name, b.password, name === u.name || !!b.admin, true);
    return { ok: true };
  },
  // Grant or revoke admin rights without touching the password. Admins only (checked here, not
  // just hidden in the UI); nobody can revoke their own rights, so at least one admin always remains.
  'POST /api/admin/user/role': ({ u, b }) => {
    admin(u);
    const name = String(b.name || '').trim().toLowerCase();
    const target = db.users[name] || bad(404, 'No such user.');
    if (typeof b.admin !== 'boolean') bad(400, 'admin must be true or false.');
    if (name === u.name && !b.admin) bad(400, "You can't remove your own admin rights.");
    if (!!target.admin !== b.admin) {
      target.admin = b.admin;
      save();
      console.log(`[users] ${u.name} ${b.admin ? 'made' : 'removed'} ${name} ${b.admin ? 'an admin' : 'as admin'}`);
    }
    return { ok: true, name, admin: target.admin };
  },
  'POST /api/admin/user/delete': ({ u, b }) => {
    admin(u);
    const name = String(b.name || '');
    if (name === u.name) bad(400, "You can't delete your own account.");
    delete db.users[name]; delete db.progress[name]; delete db.reading[name]; delete db.follows[name]; delete db.notes[name];
    if (db.discoveryFeedback) delete db.discoveryFeedback[name];
    if (db.greatestRatings) delete db.greatestRatings[name];
    for (const [k, s] of Object.entries(db.sessions)) if (s.u === name) delete db.sessions[k];
    save();
    return { ok: true };
  },
  'GET /api/admin/peering': ({ u }) => {
    admin(u);
    return { ...peerStore.publicState(), library: lib.mangas.map(m => ({ id: m.id, title: m.title, cover: url(m.cover),
      chapters: m.chapters.length, year: Number(m.meta.year || m.meta.startDate?.year) || null,
      status: String(m.meta.status || 'unknown'), description: String(m.meta.description || m.meta.synopsis || '').slice(0, 3000),
      tags: Array.isArray(m.meta.tags) ? m.meta.tags.map(tag => typeof tag === 'string' ? tag : tag.name).filter(Boolean).slice(0, 20) : [] })) };
  },
  'POST /api/admin/peering': async ({ u, b }) => {
    admin(u);
    const command = String(b.command || '');
    if (command === 'set-name') peerStore.setName(b.name);
    else if (command === 'generate') peerStore.generateIdentity(b.name);
    else if (command === 'invite') return { ...peerStore.publicState(), invitation: peerStore.createInvitation(b.url) };
    else if (command === 'import') peerStore.importInvitation(b.invitation);
    else if (command === 'probe') await peerClient.probe(peerStore, String(b.id || ''));
    else if (command === 'set') peerStore.updatePeer(String(b.id || ''), b.patch || {});
    else if (command === 'revoke-grant') peerStore.revokeGrant(String(b.id || ''));
    else if (command === 'share') {
      if (!lib.byId.has(String(b.mangaId || ''))) bad(404, 'Library manga not found');
      peerStore.setShare(String(b.id || ''), String(b.mangaId), !!b.enabled);
    }
    else if (command === 'share-set') {
      const ids = Array.isArray(b.mangaIds) ? [...new Set(b.mangaIds.map(String))] : null;
      if (!ids) bad(400, 'Manga selection is required');
      if (ids.some(id => !lib.byId.has(id))) bad(404, 'One or more library manga are no longer available');
      peerStore.setShares(String(b.id || ''), ids);
    }
    else if (command === 'grant') return { ...peerStore.publicState(), grant: peerStore.issueGrant(String(b.id || ''), b.scopes) };
    else if (command === 'accept-grant') peerStore.acceptGrant(String(b.id || ''), b.token);
    else if (command === 'remove') peerStore.removePeer(String(b.id || ''));
    else bad(400, 'Unknown peering command');
    return { ...peerStore.publicState(), library: lib.mangas.map(m => ({ id: m.id, title: m.title })) };
  },
  'GET /api/peering': ({ u }) => { admin(u); return { peers: peerStore.publicState().peers
    .map(p => ({ id: p.id, alias: p.alias, receive: !!p.receive, paired: !!p.paired, fingerprint: p.fingerprint,
      url: p.url, grantStatus: p.grantStatus, grantScopes: p.grantScopes,
      readerQueue: !!p.readerQueue, shares: p.shares, hasGrant: p.hasOutboundGrant })) }; },
  'GET /api/peering/access': async ({ u, q }) => {
    admin(u);
    const id = String(q.get('peer') || ''), peer = peerForRoute(id);
    if (!peer.paired) return { paired: false, grant: { status: 'none', scopes: [] } };
    return peerRemote(() => peerClient.access(peerStore, id));
  },
  'GET /api/peering/catalog': async ({ u, q }) => {
    admin(u);
    const id = String(q.get('peer') || '');
    const peer = peerForRoute(id);
    if (!peer.paired) bad(403, 'Verify peer identity first');
    const access = await peerRemote(() => peerClient.access(peerStore, id));
    if (access.grant.status !== 'active' || !access.grant.scopes.includes('catalog')) bad(403, 'This peer has not granted active catalog access');
    return { peer: { id, alias: peer.alias }, items: await peerRemote(() => peerClient.catalog(peerStore, id)) };
  },
  'GET /api/peering/manga': async ({ u, q }) => {
    admin(u);
    const id = String(q.get('peer') || ''), shareId = String(q.get('manga') || '');
    const peer = peerForRoute(id);
    if (!peer.paired) bad(403, 'Verify peer identity first');
    return peerRemote(() => peerClient.manga(peerStore, id, shareId));
  },
  'POST /api/peering/queue': async ({ u, b }) => {
    admin(u);
    const id = String(b.peer || ''), shareId = String(b.manga || '');
    const peer = peerForRoute(id);
    if (!peer.paired || !peer.receive || (!u.admin && !peer.readerQueue)) bad(403, 'Peer downloads are disabled for this account');
    const access = await peerRemote(() => peerClient.access(peerStore, id));
    if (!access.grant.scopes.includes('download')) bad(403, 'This peer has granted catalog browsing only');
    if (!/^m[0-9a-f]{24}$/.test(shareId)) bad(400, 'Invalid peer manga ID');
    const remote = await peerRemote(() => peerClient.manga(peerStore, id, shareId));
    const present = await peerRemote(() => peerClient.catalog(peerStore, id));
    if (!present.some(entry => entry.id === shareId)) bad(404, 'Peer manga not available');
    return scraperRequest('/api/queue', { url: `peer://${id}/${shareId}`, title: remote.title, workIdentity: remote.workIdentity,
      scope: b.scope || { mode: 'missing' }, existingPolicy: b.existingPolicy || 'skip-any',
      ...(b.libraryMangaId ? { libraryMangaId: String(b.libraryMangaId) } : {}) });
  },
  'POST /api/peering/queue-bulk': async ({ u, b }) => {
    admin(u);
    const id = String(b.peer || ''), peer = peerForRoute(id);
    const ids = Array.isArray(b.mangas) ? [...new Set(b.mangas.map(String))] : [];
    if (!ids.length || ids.length > 50 || ids.some(value => !/^m[0-9a-f]{24}$/.test(value))) bad(400, 'Select 1–50 peer titles');
    if (!peer.paired || !peer.receive) bad(403, 'Enable downloads from this peer first');
    const access = await peerRemote(() => peerClient.access(peerStore, id));
    if (access.grant.status !== 'active' || !access.grant.scopes.includes('download')) bad(403, 'This peer has not granted active download access');
    const available = new Set(await peerRemote(() => peerClient.catalog(peerStore, id)).then(items => items.map(item => item.id)));
    const results = [];
    for (const mangaId of ids) {
      if (!available.has(mangaId)) { results.push({ id: mangaId, status: 'unavailable' }); continue; }
      try {
        const remote = await peerRemote(() => peerClient.manga(peerStore, id, mangaId));
        const result = await scraperRequest('/api/queue', { url: `peer://${id}/${mangaId}`, title: remote.title, workIdentity: remote.workIdentity,
          scope: { mode: 'missing' }, existingPolicy: 'skip-any' });
        results.push({ id: mangaId, title: remote.title, status: 'queued', result });
      } catch (error) { results.push({ id: mangaId, status: 'failed', error: String(error.message || error).slice(0, 240) }); }
    }
    return { results, queued: results.filter(item => item.status === 'queued').length };
  },
  'GET /api/admin/scraper': async ({ u }) => {
    admin(u);
    try { return { available: true, ...(await scraperRequest('/api/state')) }; }
    catch (error) { return { available: false, error: error.message, url: SCRAPER_URL }; }
  },
  'POST /api/admin/scraper': async ({ u, b }) => {
    admin(u);
    const command = String(b.command || '');
    if (command === 'enqueue') return scraperRequest('/api/queue', {
      url: b.url, title: b.title, metadataSearch: b.metadataSearch,
      scope: b.scope, existingPolicy: b.existingPolicy, libraryMangaId: b.libraryMangaId,
      inspect: b.inspect === true,
    });
    if (command === 'remove') return scraperRequest('/api/queue/remove', { id: b.id });
    if (command === 'clear-completed') return scraperRequest('/api/queue/clear-completed', { source: b.source });
    if (command === 'reorder') return scraperRequest('/api/queue/reorder', { ids: b.ids });
    if (command === 'control') return scraperRequest('/api/control', { action: b.action, id: b.id });
    if (command === 'settings') return scraperRequest('/api/settings', b.settings || {});
    if (command === 'discover') return scraperRequest('/api/discovery/run', {});
    if (command === 'auto-update') return scraperRequest('/api/library/auto-update', { id: b.id, enabled: !!b.enabled });
    if (command === 'publish-legacy-ready') return scraperRequest('/api/legacy/publish-ready', {});
    bad(400, 'Unknown scraper command');
  },
};

// ---------- HTTP ----------
function sendJson(res, code, obj) {
  res.writeHead(code, { 'Content-Type': 'application/json; charset=utf-8', 'Cache-Control': 'no-store' });
  res.end(JSON.stringify(obj));
}
async function readBody(req) {
  let s = '';
  for await (const c of req) { s += c; if (s.length > 1e6) bad(413, 'Request too large'); }
  try { return s ? JSON.parse(s) : {}; } catch { bad(400, 'Invalid JSON'); }
}
async function handleApi(req, res, u, route, q) {
  let b = {};
  if (req.method === 'POST') {
    // JSON-only + same-site: plain HTML forms from other sites can't reach the API.
    if (!/^application\/json/.test(req.headers['content-type'] || '') || req.headers['sec-fetch-site'] === 'cross-site') bad(403, 'Bad request origin');
    b = (await readBody(req)) || {};
  }
  sendJson(res, 200, await route({ req, res, u, b, q }));
}
function serveFile(req, res, root, rel, cacheControl, only) {
  let file;
  try { file = path.resolve(root, decodeURIComponent(rel)); } catch { return sendJson(res, 400, { error: 'Bad path' }); }
  if (!file.startsWith(root + path.sep) || (only && !only.test(file))) return sendJson(res, 404, { error: 'Not found' });
  fs.stat(file, (err, st) => {
    if (err || !st.isFile()) return sendJson(res, 404, { error: 'Not found' });
    const etag = `"${st.size.toString(36)}-${Math.round(st.mtimeMs).toString(36)}"`;
    if (req.headers['if-none-match'] === etag) { res.writeHead(304, { ETag: etag, 'Cache-Control': cacheControl }); return res.end(); }
    res.writeHead(200, { 'Content-Type': MIME[path.extname(file).toLowerCase()] || 'application/octet-stream', 'Content-Length': st.size, ETag: etag, 'Cache-Control': cacheControl });
    if (req.method === 'HEAD') return res.end();
    fs.createReadStream(file).on('error', () => res.destroy()).pipe(res);
  });
}

http.createServer(async (req, res) => {
  try {
    const { pathname, searchParams } = new URL(req.url, 'http://localhost');
    const u = userOf(req);
    if (pathname === '/health' && req.method === 'GET') return sendJson(res, 200, { ...routes['GET /api/health'](), ok: true, ready: !scanState.error });
    if (pathname === '/api/collection-cover' && req.method === 'GET') {
      if (!u) bad(401, 'Please log in');
      const c = catalog.state.collections.find(c => c.id === searchParams.get('id'));
      if (!c?.customCover) bad(404, 'Cover not found');
      return serveFile(req, res, path.join(DATA, 'collection-covers'), c.customCover, 'private, no-cache', IMG);
    }
    if (pathname === '/api/greatest-cover' && req.method === 'GET') {
      if (!u) bad(401, 'Please log in');
      const entry = greatestById.get(searchParams.get('id'));
      if (!entry?.cover) bad(404, 'Cover not found');
      const file = greatestCovers.file(entry.cover);
      if (file) return serveFile(req, res, greatestCovers.dir, path.basename(file), 'private, max-age=31536000, immutable', IMG);
      // Not downloaded yet: the browser fetches the catalog's own URL this once.
      res.writeHead(302, { Location: entry.cover, 'Cache-Control': 'no-store' });
      return res.end();
    }
    if (pathname === '/api/peering/cover' && req.method === 'GET') {
      if (!u) bad(401, 'Please log in');
      admin(u);
      const peerId = String(searchParams.get('peer') || ''), mangaId = String(searchParams.get('manga') || ''), peer = peerForRoute(peerId);
      if (!peer.paired) bad(403, 'Verify peer identity first');
      const access = await peerRemote(() => peerClient.access(peerStore, peerId));
      if (access.grant.status !== 'active' || !access.grant.scopes.includes('catalog')) bad(403, 'This peer has not granted active catalog access');
      const image = await peerRemote(() => peerClient.cover(peerStore, peerId, mangaId));
      res.writeHead(200, { 'Content-Type': image.mime, 'Content-Length': image.buffer.length,
        ...(image.etag ? { ETag: image.etag } : {}), 'Cache-Control': 'private, max-age=3600', 'X-Content-Type-Options': 'nosniff' });
      return res.end(image.buffer);
    }
    if (pathname.startsWith('/api/')) {
      const route = routes[req.method + ' ' + pathname];
      if (!route) bad(404, 'Unknown endpoint');
      if (!u && !PUBLIC.has(pathname)) bad(401, 'Please log in');
      return await handleApi(req, res, u, route, searchParams);
    }
    if (req.method !== 'GET' && req.method !== 'HEAD') bad(405, 'Method not allowed');
    if (pathname.startsWith('/lib/')) {
      if (!u) bad(401, 'Please log in');
      let imagePath;
      try { imagePath = path.resolve(LIB, decodeURIComponent(pathname.slice(5))); } catch { bad(400, 'Bad image path'); }
      const relative = path.relative(LIB, imagePath);
      const parts = relative.split(path.sep);
      if (parts.length >= 4 && !readingAccess.status(u.name).allowed)
        bad(423, 'Reading is outside the deployment schedule.');
      return serveFile(req, res, LIB, pathname.slice(5), readingSchedule && parts.length >= 4 ? 'private, no-store' : 'private, max-age=86400', IMG);
    }
    serveFile(req, res, PUB, pathname === '/' ? 'index.html' : pathname.slice(1), 'no-cache');
  } catch (e) {
    const expected = e instanceof HttpError || e instanceof CatalogError;
    if (!expected) console.error(e);
    if (!res.headersSent) sendJson(res, expected ? e.code : 500, expected ? { error: e.message, ...e.extra } : { error: 'Internal error' });
  }
}).listen(PORT, () => console.log(`MangaCircus on http://localhost:${PORT}  (library: ${LIB}, data: ${DATA})`));

if (lib.mangas.length) refreshChanged();
else rescan();
if (SCAN_MINUTES > 0) setInterval(() => refreshChanged(), SCAN_MINUTES * 60000).unref();
// Fetch missing Greatest covers shortly after start and retry failures once a day;
// covers already on disk cost nothing.
async function warmGreatestCovers() {
  try {
    const result = await greatestCovers.warm(greatestCatalog.entries.map(entry => entry.cover));
    if (result.fetched || result.failed || result.stopped) console.log('[greatest] covers', JSON.stringify(result));
  } catch (error) { console.error('[greatest] covers', error.message); }
}
if (process.env.GREATEST_COVER_WARM !== '0') {
  setTimeout(warmGreatestCovers, 10000).unref();
  setInterval(warmGreatestCovers, 86400000).unref();
}
// Persist the last reconciliation time. Restarting a healthy reader should not
// trigger another full tree walk; overdue reconciliations run within a minute.
if (FULL_SCAN_MINUTES > 0) setInterval(() => {
  const now = Date.now();
  if (now - Math.max(lastFullAt, lastFullAttemptAt) >= FULL_SCAN_MINUTES * 60000) {
    lastFullAttemptAt = now;
    rescan();
  }
}, 60000).unref();

// A completed scraper publish increments a durable revision. Polling it here keeps the
// reader index fresh without exposing an unauthenticated rescan endpoint to the daemon.
let scraperRevision = null;
async function pollScraper() {
  try {
    const state = await scraperRequest('/api/state');
    const revision = Number(state.publishedRevision || 0);
    if (scraperRevision === null || revision > scraperRevision) {
      const checked = await refreshChanged();
      if (checked.error) throw new Error(checked.error);
      // A publication without a visible directory change should not disappear
      // because of coarse filesystem timestamps or a missed scan race.
      if (scraperRevision !== null && revision > scraperRevision && !checked.changedMangas) {
        const reconciled = await rescan();
        if (reconciled.error) throw new Error(reconciled.error);
      }
    }
    scraperRevision = revision;
  } catch { /* the reader also works when the optional scraper daemon is offline */ }
}
pollScraper();
setInterval(pollScraper, 15000).unref();

// Nightly discovery harvest; the delayed first check also covers a slot missed while the reader was down.
setInterval(checkNightly, 60000).unref();
setTimeout(checkNightly, 30000).unref();