const express = require('express');
const { Pool, types } = require('pg');
const multer = require('multer');
const rateLimit = require('express-rate-limit');
const helmet = require('helmet');
const bcrypt = require('bcrypt');
const heicConvert = require('heic-convert');

const https = require('https');
const path = require('path');
const fs = require('fs');
const crypto = require('crypto');

types.setTypeParser(1082, v => v);

const app = express();
const pool = new Pool({ connectionString: process.env.DATABASE_URL });

const apiLimiter = rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 300,
  standardHeaders: true,
  legacyHeaders: false,
  message: { error: 'Слишком много запросов. Попробуйте позже.' },
});

const entryLimiter = rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 10,
  standardHeaders: true,
  legacyHeaders: false,
  message: { error: 'Слишком много запросов. Подождите немного.' },
});

const fileLimiter = rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 300,
  standardHeaders: true,
  legacyHeaders: false,
  message: { error: 'Слишком много запросов. Попробуйте позже.' },
});

const ADMIN_PASSWORD = process.env.ADMIN_PASSWORD;
if (!ADMIN_PASSWORD) {
  console.error('FATAL: ADMIN_PASSWORD environment variable is not set. Refusing to start.');
  process.exit(1);
}

app.use(helmet({ contentSecurityPolicy: false }));
app.use(express.json({ limit: '1mb' }));
app.use('/uploads', express.static(path.join(__dirname, 'uploads')));
app.use(express.static(path.join(__dirname, 'public')));

function requireAdmin(req, res, next) {
  const token = req.headers['x-admin-token'];
  if (token !== ADMIN_PASSWORD) return res.status(401).json({ error: 'Unauthorized' });
  next();
}

function fixFilename(str) {
  try {
    return Buffer.from(str, 'latin1').toString('utf8');
  } catch {
    return str;
  }
}

const BLOCKED_EXT = /\.(?:html?|js|mjs|cjs|svg|xml|json|map|wasm|php\d?|phtml|asp|aspx|jsp|sh|bat|cmd|cgi|exe|dll|com|msi|scr|hta|vbs|py|r|rb|htaccess)$/i;
const ALLOWED_IMAGE_EXT = new Set(['.jpg', '.jpeg', '.png', '.gif', '.webp', '.bmp', '.avif', '.ico', '.heic', '.heif']);
const MAX_TOTAL_UPLOAD_BYTES = 30 * 1024 * 1024;

const upload = multer({
  storage: multer.diskStorage({
    destination: (_, __, cb) => {
      fs.mkdirSync('uploads', { recursive: true });
      cb(null, 'uploads');
    },
    filename: (_, file, cb) => {
      const original = fixFilename(file.originalname);
      const ext = path.extname(original) || '.jpg';
      cb(null, `${Date.now()}-${Math.random().toString(36).slice(2, 8)}${ext}`);
    },
  }),
  limits: { fileSize: 10 * 1024 * 1024 },
  fileFilter: (req, file, cb) => {
    file.originalname = fixFilename(file.originalname);
    const ext = path.extname(file.originalname).toLowerCase();
    if (file.fieldname === 'photo') {
      if (!file.mimetype || !file.mimetype.startsWith('image/') || !ALLOWED_IMAGE_EXT.has(ext)) {
        return cb(new Error('Only images'));
      }
    }
    if (ext && BLOCKED_EXT.test(ext)) return cb(new Error('Not allowed extension'));
    cb(null, true);
  },
});

async function getSetting(key, def) {
  const { rows } = await pool.query('SELECT value FROM settings WHERE key = $1', [key]);
  return rows.length ? rows[0].value : def;
}

const UPLOADS_DIR = path.join(__dirname, 'uploads');

function safeUnlink(relPath) {
  if (!relPath || typeof relPath !== 'string') return;
  const parts = String(relPath).replace(/\\/g, '/').replace(/^\/+/, '').split('/');
  if (parts[0] === 'uploads') parts.shift();
  if (!parts.length || parts.includes('..') || parts.includes('')) return;
  const fp = path.resolve(UPLOADS_DIR, ...parts);
  if (fp === UPLOADS_DIR || !fp.startsWith(UPLOADS_DIR + path.sep)) return;
  if (fs.existsSync(fp)) fs.unlinkSync(fp);
}

function removeUpload(file) {
  safeUnlink(file && file.path);
}

async function convertHeicPhoto(file) {
  if (!file || !file.path) return;
  const ext = (path.extname(file.originalname || '') || '').toLowerCase();
  if (ext !== '.heic' && ext !== '.heif') return;
  try {
    const outName = `${path.basename(file.path, path.extname(file.path))}.jpg`;
    const outPath = path.join(path.dirname(file.path), outName);
    const jpeg = await heicConvert({ buffer: fs.readFileSync(file.path), format: 'JPEG', quality: 0.85 });
    fs.writeFileSync(outPath, jpeg);
    safeUnlink(file.path);
    file.path = outPath;
    file.filename = outName;
    file.originalname = outName;
  } catch (e) {
    console.error('HEIC convert failed:', e);
  }
}

async function removeEntryFiles(entryId) {
  const { rows } = await pool.query(
    `SELECT photo_path AS p FROM entries WHERE id = $1
     UNION ALL
     SELECT path AS p FROM project_files WHERE entry_id = $1`,
    [entryId]
  );
  rows.forEach(r => safeUnlink(r.p));
}

async function sweepOrphanedUploads() {
  const dir = path.join(__dirname, 'uploads');
  if (!fs.existsSync(dir)) return;
  const [{ rows: photos }, { rows: files }, { rows: gphotos }] = await Promise.all([
    pool.query('SELECT photo_path AS p FROM entries WHERE photo_path IS NOT NULL'),
    pool.query('SELECT path AS p FROM project_files'),
    pool.query('SELECT photo_path AS p FROM group_photos'),
  ]);
  const refs = new Set();
  [...photos, ...files, ...gphotos].forEach(r => refs.add('/' + String(r.p).replace(/^\/+/, '')));
  for (const f of fs.readdirSync(dir)) {
    const fp = path.join(dir, f);
    if (!fs.statSync(fp).isFile()) continue;
    if (!refs.has('/uploads/' + f)) {
      try { fs.unlinkSync(fp); } catch {}
    }
  }
}

// --- Settings ---
app.get('/api/settings', requireAdmin, async (_, res) => {
  const { rows } = await pool.query('SELECT key, value FROM settings ORDER BY key');
  const out = {};
  rows.forEach(r => { out[r.key] = r.value; });
  res.json(out);
});

app.get('/api/public-settings', apiLimiter, async (_, res) => {
  const keys = ['footer_left', 'footer_right'];
  const out = {};
  for (const k of keys) out[k] = await getSetting(k, '');
  res.json(out);
});

app.put('/api/settings', requireAdmin, async (req, res) => {
  const { settings } = req.body;
  if (!settings || typeof settings !== 'object') return res.status(400).json({ error: 'settings required' });
  const client = await pool.connect();
  try {
    await client.query('BEGIN');
    for (const [key, value] of Object.entries(settings)) {
      await client.query(
        `INSERT INTO settings (key, value) VALUES ($1, $2)
         ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value`,
        [key, String(value ?? '')]
      );
    }
    await client.query('COMMIT');
    const { rows } = await pool.query('SELECT key, value FROM settings ORDER BY key');
    const out = {};
    rows.forEach(r => { out[r.key] = r.value; });
    res.json(out);
  } catch (e) {
    await client.query('ROLLBACK');
    throw e;
  } finally {
    client.release();
  }
});

// --- Backup / Restore ---
const gunzipAsync = require('util').promisify(require('zlib').gunzip);
const zlib = require('zlib');
const tar = require('tar');
const os = require('os');
const uploadBackup = multer({
  storage: multer.diskStorage({
    destination: (_, __, cb) => {
      const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'wido-up-'));
      cb(null, dir);
    },
    filename: (_, file, cb) => {
      const ext = path.extname(file.originalname) || '.bin';
      cb(null, `backup-${Date.now()}${ext}`);
    },
  }),
  limits: { fileSize: 50 * 1024 * 1024 },
});

const SAFE_NAME = /^[\w,.()-]+$/;

function isSafeUploadPath(p) {
  if (typeof p !== 'string' || !p.startsWith('/uploads/')) return false;
  const name = p.slice('/uploads/'.length);
  return name !== '' && !name.includes('/') && !name.includes('..') && SAFE_NAME.test(name);
}

function reqInt(v) {
  const n = Number(v);
  if (!Number.isInteger(n)) throw new Error('Invalid integer');
  return n;
}

function optInt(v, lo = -Infinity, hi = Infinity) {
  if (v === null || v === undefined || v === '') return null;
  const n = Number(v);
  if (!Number.isInteger(n) || n < lo || n > hi) throw new Error('Invalid integer');
  return n;
}

function reqStr(v, max) {
  if (typeof v !== 'string') throw new Error('Invalid string');
  const s = v.trim();
  if (!s || s.length > max) throw new Error('Invalid string length');
  return s;
}

function optStr(v, max) {
  if (v === null || v === undefined) return null;
  return reqStr(v, max);
}

function optTs(v) {
  if (v === null || v === undefined) return null;
  if (typeof v !== 'string' || !/^\d{4}-\d{2}-\d{2}[T ]\d{2}:\d{2}/.test(v)) throw new Error('Invalid timestamp');
  return v;
}

function optTime(v) {
  if (v === null || v === undefined) return null;
  if (typeof v !== 'string' || !/^\d{2}:\d{2}(:\d{2})?$/.test(v)) throw new Error('Invalid time');
  return v;
}

function reqToken(v) {
  if (typeof v !== 'string' || !/^[0-9a-f]{16,64}$/.test(v)) throw new Error('Invalid token');
  return v;
}

function reqUploadPath(v, max) {
  if (typeof v !== 'string' || v.length > max) throw new Error('Invalid path');
  if (!isSafeUploadPath(v)) throw new Error('Invalid upload path');
  return v;
}

function optUploadPath(v, max) {
  if (v === null || v === undefined) return null;
  return reqUploadPath(v, max);
}

function normalizeRestoreData(data) {
  const groups = (data.groups || []).map(x => ({
    id: reqInt(x.id),
    name: reqStr(x.name, 100),
    created_at: optTs(x.created_at),
    day_of_week: optInt(x.day_of_week, 0, 6),
    time_start: optTime(x.time_start),
    time_end: optTime(x.time_end),
  }));
  const students = (data.students || []).map(x => ({
    id: reqInt(x.id),
    name: reqStr(x.name, 150),
    created_at: optTs(x.created_at),
    group_id: optInt(x.group_id, 0, 2147483647),
  }));
  const entries = (data.entries || []).map(x => ({
    id: reqInt(x.id),
    student_name: reqStr(x.student_name, 150),
    group_id: reqInt(x.group_id),
    description: reqStr(x.description, 100000),
    photo_path: optUploadPath(x.photo_path, 255),
    deleted_at: optTs(x.deleted_at),
    created_at: optTs(x.created_at),
  }));
  const project_files = (data.project_files || []).map(x => ({
    id: reqInt(x.id),
    entry_id: optInt(x.entry_id, 0, 2147483647),
    token: reqToken(x.token),
    path: reqUploadPath(x.path, 255),
    name: reqStr(x.name, 255),
    created_at: optTs(x.created_at),
  }));
  const settings = {};
  for (const [k, v] of Object.entries(data.settings || {})) {
    settings[reqStr(k, 100)] = reqStr(String(v), 10000);
  }
  return { groups, students, entries, project_files, settings };
}

app.get('/api/backup', requireAdmin, async (_, res) => {
  const staging = fs.mkdtempSync(path.join(os.tmpdir(), 'wido-bk-'));
  try {
    const [g, s, e, st, pf] = await Promise.all([
      pool.query('SELECT * FROM groups ORDER BY id'),
      pool.query('SELECT * FROM students ORDER BY id'),
      pool.query('SELECT * FROM entries ORDER BY id'),
      pool.query('SELECT key, value FROM settings'),
      pool.query('SELECT * FROM project_files ORDER BY id'),
    ]);
    const settings = {};
    st.rows.forEach(r => { settings[r.key] = r.value; });
    const payload = { version: 1, created_at: new Date().toISOString(), groups: g.rows, students: s.rows, entries: e.rows, settings, project_files: pf.rows };
    fs.writeFileSync(path.join(staging, 'data.json'), JSON.stringify(payload));
    fs.mkdirSync(path.join(staging, 'uploads'), { recursive: true });
    const dir = path.join(__dirname, 'uploads');
    if (fs.existsSync(dir)) {
      for (const f of fs.readdirSync(dir)) {
        const fp = path.join(dir, f);
        if (fs.statSync(fp).isFile() && SAFE_NAME.test(f)) fs.copyFileSync(fp, path.join(staging, 'uploads', f));
      }
    }
    const stamp = new Date().toISOString().slice(0, 16).replace(/[:T]/g, '-');
    const outPath = path.join(os.tmpdir(), `whatido-backup-${stamp}.tar.gz`);
    await tar.c({ gzip: true, file: outPath, cwd: staging }, ['data.json', 'uploads']);
    const buf = fs.readFileSync(outPath);
    fs.unlinkSync(outPath);
    res.setHeader('Content-Type', 'application/gzip');
    res.setHeader('Content-Disposition', `attachment; filename="whatido-backup-${stamp}.tar.gz"`);
    res.send(buf);
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: err.message });
  } finally {
    fs.rmSync(staging, { recursive: true, force: true });
  }
});

function cleanupUpload(req) {
  try {
    if (req?.file?.destination) fs.rmSync(req.file.destination, { recursive: true, force: true });
  } catch {}
}

function peekGunzip(filePath, n) {
  return new Promise((resolve) => {
    const gunz = zlib.createGunzip();
    const bufs = [];
    let total = 0;
    let done = false;
    gunz.on('data', (c) => {
      if (done) return;
      const need = n - total;
      bufs.push(c.length > need ? c.subarray(0, need) : c);
      total += Math.min(c.length, need);
      if (total >= n) {
        done = true;
        gunz.destroy();
      }
    });
    gunz.on('error', () => resolve(null));
    gunz.on('close', () => resolve(Buffer.concat(bufs)));
    fs.createReadStream(filePath).pipe(gunz);
  });
}

app.post('/api/restore', requireAdmin, uploadBackup.single('backup'), async (req, res) => {
  if (!req.file) return res.status(400).json({ error: 'backup file required' });
  let data;
  let legacyPhotos = [];
  const staging = fs.mkdtempSync(path.join(os.tmpdir(), 'wido-rst-'));
  try {
    const head = await peekGunzip(req.file.path, 8);
    if (head && head[0] === 0x7b) {
      const buf = await fs.promises.readFile(req.file.path);
      const gunz = await gunzipAsync(buf);
      data = JSON.parse(gunz.toString('utf8'));
      legacyPhotos = data.photos || [];
    } else {
      await tar.x({ file: req.file.path, cwd: staging });
      data = JSON.parse(fs.readFileSync(path.join(staging, 'data.json'), 'utf8'));
    }
  } catch {
    fs.rmSync(staging, { recursive: true, force: true });
    cleanupUpload(req);
    return res.status(400).json({ error: 'Неверный файл бэкапа' });
  }
  if (!data || data.version !== 1 || !Array.isArray(data.groups)) {
    fs.rmSync(staging, { recursive: true, force: true });
    cleanupUpload(req);
    return res.status(400).json({ error: 'Неверный формат бэкапа' });
  }
  let ndata;
  try {
    ndata = normalizeRestoreData(data);
  } catch (e) {
    fs.rmSync(staging, { recursive: true, force: true });
    cleanupUpload(req);
    return res.status(400).json({ error: 'Неверный формат бэкапа: ' + e.message });
  }
  const client = await pool.connect();
  try {
    await client.query('BEGIN');
    await client.query('DELETE FROM entries');
    await client.query('DELETE FROM students');
    await client.query('DELETE FROM groups');
    for (const x of ndata.groups) {
      await client.query(
        'INSERT INTO groups (id, name, created_at, day_of_week, time_start, time_end) VALUES ($1,$2,$3,$4,$5,$6)',
        [x.id, x.name, x.created_at, x.day_of_week, x.time_start, x.time_end]
      );
    }
    for (const x of ndata.students) {
      await client.query(
        'INSERT INTO students (id, name, created_at, group_id) VALUES ($1,$2,$3,$4)',
        [x.id, x.name, x.created_at, x.group_id]
      );
    }
    for (const x of ndata.entries) {
      await client.query(
        'INSERT INTO entries (id, student_name, group_id, description, photo_path, deleted_at, created_at) VALUES ($1,$2,$3,$4,$5,$6,$7)',
        [x.id, x.student_name, x.group_id, x.description, x.photo_path, x.deleted_at, x.created_at]
      );
    }
    for (const x of ndata.project_files) {
      await client.query(
        'INSERT INTO project_files (id, entry_id, token, path, name, created_at) VALUES ($1,$2,$3,$4,$5,$6)',
        [x.id, x.entry_id, x.token, x.path, x.name, x.created_at]
      );
    }
    for (const [k, v] of Object.entries(ndata.settings)) {
      await client.query(
        'INSERT INTO settings (key, value) VALUES ($1,$2) ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value',
        [k, String(v ?? '')]
      );
    }
    for (const tbl of ['groups', 'students', 'entries', 'project_files']) {
      const r = await client.query('SELECT COALESCE(MAX(id), 1) AS m FROM ' + tbl);
      await client.query('SELECT setval(pg_get_serial_sequence($1, $2), $3)', [tbl, 'id', r.rows[0].m]);
    }
    await client.query('COMMIT');
  } catch (e) {
    await client.query('ROLLBACK');
    fs.rmSync(staging, { recursive: true, force: true });
    cleanupUpload(req);
    throw e;
  } finally {
    client.release();
  }
  const dir = path.join(__dirname, 'uploads');
  fs.mkdirSync(dir, { recursive: true });
  if (legacyPhotos.length) {
    for (const p of legacyPhotos) {
      if (!p.path || !SAFE_NAME.test(p.path)) continue;
      fs.writeFileSync(path.join(dir, p.path), Buffer.from(p.data, 'base64'));
    }
  } else {
    const src = path.join(staging, 'uploads');
    if (fs.existsSync(src)) {
      for (const f of fs.readdirSync(src)) {
        if (!SAFE_NAME.test(f)) continue;
        const fp = path.join(src, f);
        if (fs.statSync(fp).isFile()) fs.copyFileSync(fp, path.join(dir, f));
      }
    }
  }
  fs.rmSync(staging, { recursive: true, force: true });
  cleanupUpload(req);
  await sweepOrphanedUploads().catch(err => console.error('Upload sweep:', err));
  res.json({ ok: true });
});

// --- Share links ---
function normDates(o) {
  if (o && o.date_from) o.date_from = o.date_from instanceof Date ? o.date_from.toISOString().slice(0, 10) : String(o.date_from).slice(0, 10);
  if (o && o.date_to) o.date_to = o.date_to instanceof Date ? o.date_to.toISOString().slice(0, 10) : String(o.date_to).slice(0, 10);
  return o;
}
app.get('/api/links', requireAdmin, async (_, res) => {
  const { rows } = await pool.query(
    `SELECT l.*, g.name AS group_name FROM share_links l
     LEFT JOIN groups g ON g.id = l.group_id ORDER BY l.created_at DESC`
  );
  rows.forEach(normDates);
  res.json(rows);
});

app.post('/api/links', requireAdmin, async (req, res) => {
  const { name, group_id, student_name, date_from, date_to, anonymize_names, expires_at, access_password } = req.body;
  if (!name?.trim()) return res.status(400).json({ error: 'Название обязательно' });
  const token = crypto.randomBytes(20).toString('hex');
  let passwordHash = null;
  if (access_password && access_password.trim()) {
    passwordHash = await bcrypt.hash(access_password.trim(), 10);
  }
  let expiresAt = null;
  if (expires_at) {
    const parsed = new Date(expires_at);
    if (isNaN(parsed.getTime())) {
      return res.status(400).json({ error: 'Неверный формат даты истечения' });
    }
    expiresAt = parsed.toISOString();
  } else {
    // Default 7 days from now
    const defaultExp = new Date(Date.now() + 7 * 24 * 60 * 60 * 1000);
    expiresAt = defaultExp.toISOString();
  }
  const { rows } = await pool.query(
    `INSERT INTO share_links (token, name, group_id, student_name, date_from, date_to, anonymize_names, expires_at, access_password_hash)
     VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9) RETURNING *`,
    [token, name.trim(), group_id || null, student_name || null, date_from || null, date_to || null, anonymize_names || false, expiresAt, passwordHash]
  );
  res.status(201).json(normDates(rows[0]));
});

app.put('/api/links/:id', requireAdmin, async (req, res) => {
  const { name, group_id, student_name, date_from, date_to, anonymize_names, expires_at, access_password } = req.body;
  if (!name?.trim()) return res.status(400).json({ error: 'Название обязательно' });
  let passwordHash = undefined;
  if (access_password !== undefined) {
    if (access_password && access_password.trim()) {
      passwordHash = await bcrypt.hash(access_password.trim(), 10);
    } else {
      passwordHash = null; // Clear password if empty string sent
    }
  }
  let expiresAt = undefined;
  if (expires_at !== undefined) {
    if (expires_at) {
      const parsed = new Date(expires_at);
      if (isNaN(parsed.getTime())) {
        return res.status(400).json({ error: 'Неверный формат даты истечения' });
      }
      expiresAt = parsed.toISOString();
    } else {
      expiresAt = null; // Clear expiry if null sent
    }
  }
  const fields = ['name = $1', 'group_id = $2', 'student_name = $3', 'date_from = $4', 'date_to = $5', 'anonymize_names = $6'];
  const values = [name.trim(), group_id || null, student_name || null, date_from || null, date_to || null, anonymize_names || false];
  let paramIdx = 7;
  if (passwordHash !== undefined) {
    fields.push(`access_password_hash = $${paramIdx++}`);
    values.push(passwordHash);
  }
  if (expiresAt !== undefined) {
    fields.push(`expires_at = $${paramIdx++}`);
    values.push(expiresAt);
  }
  values.push(req.params.id);
  const { rows } = await pool.query(
    `UPDATE share_links SET ${fields.join(', ')} WHERE id = $${paramIdx} RETURNING *`,
    values
  );
  if (!rows.length) return res.status(404).json({ error: 'Не найдено' });
  res.json(normDates(rows[0]));
});

app.delete('/api/links/:id', requireAdmin, async (req, res) => {
  await pool.query('DELETE FROM share_links WHERE id = $1', [req.params.id]);
  res.json({ ok: true });
});

app.get('/api/share/:token', fileLimiter, async (req, res) => {
  const { rows } = await pool.query(
    `SELECT l.*, g.name AS group_name FROM share_links l
     LEFT JOIN groups g ON g.id = l.group_id WHERE l.token = $1`,
    [req.params.token]
  );
  if (!rows.length) return res.status(404).json({ error: 'Ссылка не найдена' });
  normDates(rows[0]);
  const l = rows[0];

  // Check expiry
  if (l.expires_at && new Date(l.expires_at) < new Date()) {
    return res.status(410).json({ error: 'Срок действия ссылки истёк' });
  }

  // Check password
  if (l.access_password_hash) {
    const providedPassword = req.headers['x-share-password'] || req.query.password;
    if (!providedPassword) {
      return res.status(401).json({ error: 'Требуется пароль', passwordRequired: true });
    }
    const valid = await bcrypt.compare(providedPassword, l.access_password_hash);
    if (!valid) {
      return res.status(401).json({ error: 'Неверный пароль' });
    }
  }

  const conditions = [];
  const params = [];
  if (l.group_id) { params.push(l.group_id); conditions.push(`e.group_id = $${params.length}`); }
  if (l.student_name) { params.push(l.student_name); conditions.push(`e.student_name = $${params.length}`); }
  if (l.date_from) { params.push(l.date_from); conditions.push(`e.created_at >= $${params.length}::date`); }
  if (l.date_to) { params.push(l.date_to); conditions.push(`e.created_at < ($${params.length}::date + interval '1 day')`); }
  conditions.push('e.deleted_at IS NULL');
  const where = conditions.length ? ' WHERE ' + conditions.join(' AND ') : '';
  const { rows: entries } = await pool.query(
    `SELECT e.*, g.name AS group_name FROM entries e
     JOIN groups g ON g.id = e.group_id${where} ORDER BY e.created_at DESC`,
    params
  );
  let files = {};
  if (entries.length) {
    const fRes = await pool.query(
      'SELECT entry_id, token, name FROM project_files WHERE entry_id = ANY($1) ORDER BY id',
      [entries.map(r => r.id)]
    );
    fRes.rows.forEach(f => { (files[f.entry_id] = files[f.entry_id] || []).push({ token: f.token, name: f.name }); });
  }
  entries.forEach(r => { r.files = files[r.id] || []; });

  // Anonymize names if enabled
  if (l.anonymize_names) {
    const nameMap = new Map();
    let counter = 1;
    entries.forEach(e => {
      if (!nameMap.has(e.student_name)) {
        nameMap.set(e.student_name, `Ученик ${counter++}`);
      }
      e.student_name = nameMap.get(e.student_name);
    });
  }

  let photos = [];
  if (l.group_id) {
    const pRes = await pool.query(
      `SELECT id, photo_path, caption, taken_at, created_at FROM group_photos
       WHERE group_id = $1 ORDER BY taken_at DESC NULLS LAST, created_at DESC LIMIT 12`,
      [l.group_id]
    );
    photos = pRes.rows.map(r => ({ id: r.id, photo_path: r.photo_path, caption: r.caption, taken_at: r.taken_at, created_at: r.created_at }));
  }
  res.json({
    name: l.name,
    group_name: l.group_name,
    student_name: l.student_name,
    group_id: l.group_id,
    date_from: l.date_from,
    date_to: l.date_to,
    created_at: l.created_at,
    anonymize_names: l.anonymize_names,
    entries,
    photos,
  });
});

app.get('/api/share/:shareToken/files/:fileToken', fileLimiter, async (req, res) => {
  const { shareToken, fileToken } = req.params;
  const { rows: shareRows } = await pool.query(
    `SELECT l.* FROM share_links l WHERE l.token = $1`, [shareToken]
  );
  if (!shareRows.length) return res.status(404).json({ error: 'Ссылка не найдена' });
  const l = shareRows[0];
  if (l.expires_at && new Date(l.expires_at) < new Date()) {
    return res.status(410).json({ error: 'Срок действия ссылки истёк' });
  }
  if (l.access_password_hash) {
    const providedPassword = req.headers['x-share-password'] || req.query.password;
    if (!providedPassword) return res.status(401).json({ error: 'Требуется пароль' });
    const valid = await bcrypt.compare(providedPassword, l.access_password_hash);
    if (!valid) return res.status(401).json({ error: 'Неверный пароль' });
  }
  const conditions = ['e.deleted_at IS NULL'];
  const params = [];
  if (l.group_id) { params.push(l.group_id); conditions.push(`e.group_id = $${params.length}`); }
  if (l.student_name) { params.push(l.student_name); conditions.push(`e.student_name = $${params.length}`); }
  if (l.date_from) { params.push(l.date_from); conditions.push(`e.created_at >= $${params.length}::date`); }
  if (l.date_to) { params.push(l.date_to); conditions.push(`e.created_at < ($${params.length}::date + interval '1 day')`); }
  params.push(fileToken);
  const { rows } = await pool.query(
    `SELECT pf.path, pf.name FROM project_files pf
     JOIN entries e ON e.id = pf.entry_id
     WHERE pf.token = $${params.length} AND ${conditions.join(' AND ')}`,
    params
  );
  if (!rows.length) return res.status(404).json({ error: 'Not found' });
  const r = rows[0];
  const fp = path.join(__dirname, r.path);
  if (!fs.existsSync(fp)) return res.status(404).json({ error: 'File missing' });
  if (isImageName(r.name)) res.sendFile(fp);
  else res.download(fp, r.name);
});

app.get('/s/:token', (req, res) => {
  res.sendFile(path.join(__dirname, 'public', 'share.html'));
});

// --- Groups CRUD ---
app.get('/api/groups', apiLimiter, async (_, res) => {
  const { rows } = await pool.query(
    `SELECT g.*, gp.photo_path AS cover_path
     FROM groups g
     LEFT JOIN LATERAL (
       SELECT photo_path FROM group_photos
       WHERE group_id = g.id
       ORDER BY taken_at DESC NULLS LAST, created_at DESC LIMIT 1
     ) gp ON true
     ORDER BY g.id`
  );
  res.json(rows);
});

app.get('/api/groups/active', apiLimiter, async (_, res) => {
  const { rows } = await pool.query(`
    SELECT * FROM groups
    WHERE day_of_week IS NOT NULL
      AND time_start IS NOT NULL
      AND time_end IS NOT NULL
      AND day_of_week = EXTRACT(DOW FROM (now() AT TIME ZONE 'Europe/Moscow'))::int
      AND (now() AT TIME ZONE 'Europe/Moscow')::time BETWEEN time_start AND time_end
    ORDER BY id
  `);
  res.json(rows);
});

app.put('/api/groups/:id', requireAdmin, async (req, res) => {
  const { name, day_of_week, time_start, time_end } = req.body;
  try {
    const { rows } = await pool.query(
      `UPDATE groups SET
        name = COALESCE($1, name),
        day_of_week = $2,
        time_start = $3,
        time_end = $4
       WHERE id = $5 RETURNING *`,
      [name,
       day_of_week === undefined || day_of_week === null || day_of_week === '' ? null : day_of_week,
       time_start || null, time_end || null, req.params.id]
    );
    res.json(rows[0]);
  } catch (e) {
    if (e.code === '23505') return res.status(409).json({ error: 'Duplicate name' });
    throw e;
  }
});

app.post('/api/groups', requireAdmin, async (req, res) => {
  const { name } = req.body;
  if (!name?.trim()) return res.status(400).json({ error: 'Name required' });
  try {
    const { rows } = await pool.query(
      'INSERT INTO groups (name) VALUES ($1) RETURNING *',
      [name.trim()]
    );
    res.status(201).json(rows[0]);
  } catch (e) {
    if (e.code === '23505') return res.status(409).json({ error: 'Duplicate' });
    throw e;
  }
});

app.delete('/api/groups/:id', requireAdmin, async (req, res) => {
  const { rows } = await pool.query(
    'SELECT photo_path FROM group_photos WHERE group_id = $1',
    [req.params.id]
  );
  rows.forEach(r => safeUnlink(r.photo_path));
  await pool.query('DELETE FROM groups WHERE id = $1', [req.params.id]);
  res.json({ ok: true });
});

app.get('/api/groups/:id/photos', requireAdmin, async (req, res) => {
  const { limit, offset } = req.query;
  const { rows: crows } = await pool.query(
    'SELECT count(*)::int AS n FROM group_photos WHERE group_id = $1',
    [req.params.id]
  );
  const total = crows[0].n;
  let q = `SELECT * FROM group_photos WHERE group_id = $1
           ORDER BY taken_at DESC NULLS LAST, created_at DESC`;
  const qparams = [req.params.id];
  const lim = parseInt(limit, 10);
  if (lim > 0) { qparams.push(lim); q += ` LIMIT $${qparams.length}`; }
  const off = parseInt(offset, 10);
  if (off > 0) { qparams.push(off); q += ` OFFSET $${qparams.length}`; }
  const { rows } = await pool.query(q, qparams);
  res.json({ photos: rows, total });
});

const groupPhotoUpload = upload.single('photo');
app.post('/api/groups/:id/photos', requireAdmin, (req, res, next) => {
  groupPhotoUpload(req, res, (err) => {
    if (!err) return next();
    if (err.code === 'LIMIT_FILE_SIZE') return res.status(400).json({ error: 'Файл слишком большой (макс. 10 МБ)' });
    if (err.message === 'Only images') return res.status(400).json({ error: 'Фото: допустимы только изображения (jpg, png, gif, webp, bmp, avif, ico, heic, heif)' });
    if (err.message === 'Not allowed extension') return res.status(400).json({ error: 'Недопустимый тип файла (*.html, *.js, *.svg и т.п. запрещены)' });
    return res.status(400).json({ error: 'Недопустимый файл' });
  });
}, async (req, res) => {
  const { caption, taken_at } = req.body;
  if (!req.file) return res.status(400).json({ error: 'Файл обязателен' });
  try {
    await convertHeicPhoto(req.file);
    const { rows } = await pool.query(
      `INSERT INTO group_photos (group_id, photo_path, caption, taken_at)
       VALUES ($1, $2, $3, $4) RETURNING *`,
      [req.params.id, `/uploads/${req.file.filename}`, caption?.trim() || null, taken_at || null]
    );
    res.status(201).json(rows[0]);
  } catch (e) {
    safeUnlink(`uploads/${req.file.filename}`);
    throw e;
  }
});

app.put('/api/groups/:id/photos/:photoId', requireAdmin, async (req, res) => {
  const { caption, taken_at } = req.body;
  const { rows } = await pool.query(
    `UPDATE group_photos SET
       caption = $1,
       taken_at = $2
     WHERE id = $3 AND group_id = $4 RETURNING *`,
    [caption?.trim() || null, taken_at || null, req.params.photoId, req.params.id]
  );
  if (!rows.length) return res.status(404).json({ error: 'Не найдено' });
  res.json(rows[0]);
});

app.delete('/api/groups/:id/photos/:photoId', requireAdmin, async (req, res) => {
  const { rows } = await pool.query(
    'SELECT photo_path FROM group_photos WHERE id = $1 AND group_id = $2',
    [req.params.photoId, req.params.id]
  );
  if (!rows.length) return res.status(404).json({ error: 'Не найдено' });
  safeUnlink(rows[0].photo_path);
  await pool.query('DELETE FROM group_photos WHERE id = $1', [req.params.photoId]);
  res.json({ ok: true });
});

// --- Students CRUD ---
app.get('/api/students', apiLimiter, async (_, res) => {
  const { rows } = await pool.query(
    `SELECT s.*, g.name AS group_name FROM students s
     LEFT JOIN groups g ON g.id = s.group_id ORDER BY s.name`
  );
  res.json(rows);
});

app.get('/api/students/names', requireAdmin, async (_, res) => {
  const { rows } = await pool.query(
    'SELECT DISTINCT student_name AS name FROM entries WHERE student_name IS NOT NULL AND student_name <> \'\' ORDER BY student_name'
  );
  res.json(rows.map(r => r.name));
});

app.post('/api/students', requireAdmin, async (req, res) => {
  const { name, group_id } = req.body;
  if (!name?.trim()) return res.status(400).json({ error: 'Name required' });
  const gid = group_id ? Number(group_id) : null;
  try {
    const { rows } = await pool.query(
      'INSERT INTO students (name, group_id) VALUES ($1, $2) RETURNING *',
      [name.trim(), gid]
    );
    res.status(201).json(rows[0]);
  } catch (e) {
    if (e.code === '23505') return res.status(409).json({ error: 'Duplicate' });
    throw e;
  }
});

app.put('/api/students/:id', requireAdmin, async (req, res) => {
  const { name, group_id } = req.body;
  if (!name?.trim()) return res.status(400).json({ error: 'Name required' });
  try {
    const { rows } = await pool.query(
      `UPDATE students SET
        name = $1,
        group_id = $2
       WHERE id = $3 RETURNING *`,
      [name.trim(),
       group_id === undefined || group_id === null || group_id === '' ? null : group_id,
       req.params.id]
    );
    if (!rows.length) return res.status(404).json({ error: 'Not found' });
    res.json(rows[0]);
  } catch (e) {
    if (e.code === '23505') return res.status(409).json({ error: 'Duplicate' });
    throw e;
  }
});

app.post('/api/students/batch-group', requireAdmin, async (req, res) => {
  const { group_id, student_ids } = req.body;
  if (!group_id || !Array.isArray(student_ids) || !student_ids.length) {
    return res.status(400).json({ error: 'group_id and student_ids required' });
  }
  const ids = [...new Set(student_ids.map(Number).filter(Boolean))];
  if (!ids.length) return res.status(400).json({ error: 'No valid students' });
  const params = [group_id, ...ids];
  const placeholders = ids.map((_, i) => `$${i + 2}`).join(',');
  const { rows } = await pool.query(
    `UPDATE students SET group_id = $1 WHERE id IN (${placeholders}) RETURNING id`,
    params
  );
  res.json({ ok: true, updated: rows.length });
});

app.delete('/api/students/:id', requireAdmin, async (req, res) => {
  await pool.query('DELETE FROM students WHERE id = $1', [req.params.id]);
  res.json({ ok: true });
});

// --- Entries ---
app.get('/api/entries', requireAdmin, async (req, res) => {
  const { group_id, date_from, date_to, student_name, search, limit, offset, deleted } = req.query;
  const conditions = [];
  const params = [];
  if (deleted === '1') conditions.push('e.deleted_at IS NOT NULL');
  else conditions.push('e.deleted_at IS NULL');
  if (group_id) { params.push(group_id); conditions.push(`e.group_id = $${params.length}`); }
  if (date_from) { params.push(date_from); conditions.push(`e.created_at >= $${params.length}::date`); }
  if (date_to) { params.push(date_to); conditions.push(`e.created_at < ($${params.length}::date + interval '1 day')`); }
  if (student_name) { params.push(student_name); conditions.push(`e.student_name = $${params.length}`); }
  if (search) { params.push(`%${search}%`); conditions.push(`(e.student_name ILIKE $${params.length} OR e.description ILIKE $${params.length})`); }
  const where = conditions.length ? ' WHERE ' + conditions.join(' AND ') : '';
  const { rows: crows } = await pool.query(
    `SELECT count(*)::int AS n FROM entries e JOIN groups g ON g.id = e.group_id${where}`,
    params
  );
  const total = crows[0].n;
  let q = `SELECT e.*, g.name AS group_name FROM entries e
           JOIN groups g ON g.id = e.group_id${where} ORDER BY e.created_at DESC`;
  const qparams = params.slice();
  const lim = parseInt(limit, 10);
  if (lim > 0) { qparams.push(lim); q += ` LIMIT $${qparams.length}`; }
  const off = parseInt(offset, 10);
  if (off > 0) { qparams.push(off); q += ` OFFSET $${qparams.length}`; }
  const { rows } = await pool.query(q, qparams);
  let files;
  if (rows.length) {
    const ids = rows.map(r => r.id);
    const fRes = await pool.query(
      'SELECT id, entry_id, token, name FROM project_files WHERE entry_id = ANY($1) ORDER BY id',
      [ids]
    );
    files = {};
    fRes.rows.forEach(f => { (files[f.entry_id] = files[f.entry_id] || []).push(f); });
  } else {
    files = {};
  }
  rows.forEach(r => { r.files = files[r.id] || []; });
  res.json({ entries: rows, total });
});

app.get('/api/entries/:id/files', requireAdmin, async (req, res) => {
  const { rows } = await pool.query(
    'SELECT id, token, name FROM project_files WHERE entry_id = $1 ORDER BY id',
    [req.params.id]
  );
  res.json(rows);
});

function isImageName(name) {
  return /\.(jpe?g|png|gif|webp|bmp|avif|ico)$/i.test(name || '');
}

app.get('/api/files', requireAdmin, async (req, res) => {
  const { search, student_name, group_id, date_from, date_to, limit, offset } = req.query;
  const conditions = [];
  const params = [];
  conditions.push('e.deleted_at IS NULL');
  if (search) { params.push(`%${search}%`); conditions.push(`pf.name ILIKE $${params.length}`); }
  if (student_name) { params.push(student_name); conditions.push(`e.student_name = $${params.length}`); }
  if (group_id) { params.push(group_id); conditions.push(`e.group_id = $${params.length}`); }
  if (date_from) { params.push(date_from); conditions.push(`e.created_at >= $${params.length}::date`); }
  if (date_to) { params.push(date_to); conditions.push(`e.created_at < ($${params.length}::date + interval '1 day')`); }
  const where = conditions.length ? ' WHERE ' + conditions.join(' AND ') : '';
  const { rows: crows } = await pool.query(
    `SELECT count(*)::int AS n FROM project_files pf JOIN entries e ON e.id = pf.entry_id${where}`,
    params
  );
  const total = crows[0].n;
  let q = `SELECT pf.id, pf.token, pf.name, pf.path, e.student_name, e.created_at, g.name AS group_name
           FROM project_files pf
           JOIN entries e ON e.id = pf.entry_id
           JOIN groups g ON g.id = e.group_id${where}
           ORDER BY pf.id DESC`;
  const qparams = params.slice();
  const lim = parseInt(limit, 10);
  if (lim > 0) { qparams.push(lim); q += ` LIMIT $${qparams.length}`; }
  const off = parseInt(offset, 10);
  if (off > 0) { qparams.push(off); q += ` OFFSET $${qparams.length}`; }
  const { rows } = await pool.query(q, qparams);
  const files = rows.map(r => {
    let size = 0;
    try { size = fs.statSync(path.join(__dirname, r.path)).size; } catch {}
    return { id: r.id, token: r.token, name: r.name, student_name: r.student_name, group_name: r.group_name, created_at: r.created_at, size };
  });
  res.json({ files, total });
});

app.get('/api/files/detached', requireAdmin, async (req, res) => {
  const { search, limit, offset } = req.query;
  const conditions = [];
  const params = [];
  conditions.push('entry_id IS NULL');
  if (search) { params.push(`%${search}%`); conditions.push(`name ILIKE $${params.length}`); }
  const where = conditions.join(' AND ');
  const { rows: crows } = await pool.query(
    `SELECT count(*)::int AS n FROM project_files WHERE ${where}`,
    params
  );
  const total = crows[0].n;
  let q = `SELECT id, token, name, path, created_at FROM project_files
           WHERE ${where} ORDER BY created_at DESC`;
  const qparams = params.slice();
  const lim = parseInt(limit, 10);
  if (lim > 0) { qparams.push(lim); q += ` LIMIT $${qparams.length}`; }
  const off = parseInt(offset, 10);
  if (off > 0) { qparams.push(off); q += ` OFFSET $${qparams.length}`; }
  const { rows } = await pool.query(q, qparams);
  const files = rows.map(r => {
    let size = 0;
    try { size = fs.statSync(path.join(__dirname, r.path)).size; } catch {}
    return { id: r.id, token: r.token, name: r.name, created_at: r.created_at, size };
  });
  res.json({ files, total });
});

app.post('/api/files/:id/detach', requireAdmin, async (req, res) => {
  const { rows } = await pool.query(
    'UPDATE project_files SET entry_id = NULL, detached_at = now() WHERE id = $1 RETURNING *',
    [req.params.id]
  );
  if (!rows.length) return res.status(404).json({ error: 'Не найдено' });
  res.json({ ok: true });
});

app.delete('/api/files/:id', requireAdmin, async (req, res) => {
  const { rows } = await pool.query('SELECT path FROM project_files WHERE id = $1', [req.params.id]);
  if (!rows.length) return res.status(404).json({ error: 'Не найдено' });
  safeUnlink(rows[0].path);
  await pool.query('DELETE FROM project_files WHERE id = $1', [req.params.id]);
  res.json({ ok: true });
});

app.get('/api/files/:token', fileLimiter, async (req, res) => {
  const { rows } = await pool.query('SELECT path, name FROM project_files WHERE token = $1', [req.params.token]);
  if (!rows.length) return res.status(404).json({ error: 'Not found' });
  const r = rows[0];
  const fp = path.join(__dirname, r.path);
  if (!fs.existsSync(fp)) return res.status(404).json({ error: 'File missing' });
  if (isImageName(r.name)) res.sendFile(fp);
  else res.download(fp, r.name);
});

app.get('/api/stats', requireAdmin, async (_, res) => {
  const [entries, trash, groups, students, today] = await Promise.all([
    pool.query('SELECT count(*)::int AS n FROM entries WHERE deleted_at IS NULL'),
    pool.query('SELECT count(*)::int AS n FROM entries WHERE deleted_at IS NOT NULL'),
    pool.query('SELECT count(*)::int AS n FROM groups'),
    pool.query('SELECT count(DISTINCT student_name)::int AS n FROM entries WHERE deleted_at IS NULL'),
    pool.query("SELECT count(*)::int AS n FROM entries WHERE deleted_at IS NULL AND created_at >= now()::date"),
  ]);
  res.json({
    entries: entries.rows[0].n,
    trash: trash.rows[0].n,
    groups: groups.rows[0].n,
    students: students.rows[0].n,
    today: today.rows[0].n,
  });
});

app.get('/api/dashboard', requireAdmin, async (req, res) => {
  const DAYS = ['Вс', 'Пн', 'Вт', 'Ср', 'Чт', 'Пт', 'Сб'];
  const [stats, activity, active, recent, top, photos, latestPhotos] = await Promise.all([
    (async () => {
      const [entries, trash, groups, students, today] = await Promise.all([
        pool.query('SELECT count(*)::int AS n FROM entries WHERE deleted_at IS NULL'),
        pool.query('SELECT count(*)::int AS n FROM entries WHERE deleted_at IS NOT NULL'),
        pool.query('SELECT count(*)::int AS n FROM groups'),
        pool.query('SELECT count(DISTINCT student_name)::int AS n FROM entries WHERE deleted_at IS NULL'),
        pool.query("SELECT count(*)::int AS n FROM entries WHERE deleted_at IS NULL AND created_at >= now()::date"),
      ]);
      return { entries: entries.rows[0].n, trash: trash.rows[0].n, groups: groups.rows[0].n, students: students.rows[0].n, today: today.rows[0].n };
    })(),
    pool.query(
      `SELECT to_char(created_at, 'YYYY-MM-DD') AS d, count(*)::int AS n
       FROM entries WHERE deleted_at IS NULL
         AND created_at >= (now() - interval '13 days')::date
       GROUP BY 1 ORDER BY 1`
    ),
    pool.query(
      `SELECT * FROM groups
       WHERE day_of_week IS NOT NULL AND time_start IS NOT NULL AND time_end IS NOT NULL
         AND day_of_week = EXTRACT(DOW FROM (now() AT TIME ZONE 'Europe/Moscow'))::int
         AND (now() AT TIME ZONE 'Europe/Moscow')::time BETWEEN time_start AND time_end
       ORDER BY id`
    ),
    pool.query(
      `SELECT e.id, e.student_name, e.photo_path, e.created_at, g.name AS group_name
       FROM entries e JOIN groups g ON g.id = e.group_id
       WHERE e.deleted_at IS NULL
       ORDER BY e.created_at DESC LIMIT 7`
    ),
    pool.query(
      `SELECT student_name, count(*)::int AS n FROM entries
       WHERE deleted_at IS NULL GROUP BY student_name ORDER BY n DESC, student_name LIMIT 5`
    ),
    pool.query(
      `SELECT gp.id, gp.photo_path, gp.caption, gp.taken_at, g.name AS group_name
       FROM group_photos gp JOIN groups g ON g.id = gp.group_id
       ORDER BY gp.taken_at DESC NULLS LAST, gp.created_at DESC LIMIT 8`
    ),
    pool.query(
      `SELECT photo_path, taken_at FROM group_photos
       ORDER BY taken_at DESC NULLS LAST, created_at DESC LIMIT 1`
    ),
  ]);
  const activeGroups = active.rows.map(g => ({
    id: g.id,
    name: g.name,
    day_label: DAYS[g.day_of_week],
    time_start: (g.time_start || '').slice(0, 5),
    time_end: (g.time_end || '').slice(0, 5),
  }));
  res.json({
    stats: stats,
    activity: activity.rows,
    active_groups: activeGroups,
    recent_entries: recent.rows,
    top_students: top.rows,
    photos: photos.rows,
    latest_photo_taken: (latestPhotos.rows[0] || {}).taken_at || null,
  });
});

const entryFields = upload.fields([{ name: 'photo', maxCount: 1 }, { name: 'files', maxCount: 10 }]);
app.post('/api/entries', entryLimiter, (req, res, next) => {
  entryFields(req, res, (err) => {
    if (!err) return next();
    if (err.code === 'LIMIT_FILE_SIZE') return res.status(400).json({ error: 'Файл слишком большой (макс. 10 МБ)' });
    if (err.message === 'Only images') return res.status(400).json({ error: 'Фото: допустимы только изображения (jpg, png, gif, webp, bmp, avif, ico, heic, heif)' });
    if (err.message === 'Not allowed extension') return res.status(400).json({ error: 'Недопустимый тип файла (*.html, *.js, *.svg и т.п. запрещены)' });
    return res.status(400).json({ error: 'Недопустимый файл' });
  });
}, async (req, res) => {
  const { student_name, group_id, description, website } = req.body;
  const photo = req.files?.photo?.[0] || null;
  const projectFiles = req.files?.files || [];
  if (website) {
    removeUpload(photo);
    projectFiles.forEach(removeUpload);
    return res.status(400).json({ error: 'Spam detected' });
  }
  if (!student_name?.trim() || !group_id || !description?.trim()) {
    removeUpload(photo);
    projectFiles.forEach(removeUpload);
    return res.status(400).json({ error: 'All fields required' });
  }
  const totalBytes = (photo?.size || 0) + projectFiles.reduce((s, f) => s + (f.size || 0), 0);
  if (totalBytes > MAX_TOTAL_UPLOAD_BYTES) {
    removeUpload(photo);
    projectFiles.forEach(removeUpload);
    return res.status(400).json({ error: 'Суммарный размер файлов слишком велик (макс. 30 МБ)' });
  }
  const gid = Number.parseInt(group_id, 10);
  if (!Number.isInteger(gid)) {
    removeUpload(photo);
    projectFiles.forEach(removeUpload);
    return res.status(400).json({ error: 'Группа не найдена' });
  }
  const grpCheck = await pool.query('SELECT id FROM groups WHERE id = $1', [gid]);
  if (!grpCheck.rows.length) {
    removeUpload(photo);
    projectFiles.forEach(removeUpload);
    return res.status(400).json({ error: 'Группа не найдена' });
  }
  const intervalMin = parseInt(await getSetting('spam_interval_min', '30'), 10) || 0;
  if (intervalMin > 0) {
    const dup = await pool.query(
      'SELECT count(*)::int AS n FROM entries WHERE student_name = $1 AND created_at >= now() - ($2 || \' minutes\')::interval',
      [student_name.trim(), intervalMin]
    );
    if (dup.rows[0].n > 0) {
      removeUpload(photo);
      projectFiles.forEach(removeUpload);
      return res.status(429).json({ error: `Уже ответили: подождите ${intervalMin} минут` });
    }
  }
  await convertHeicPhoto(photo);
  const photo_path = photo ? `/uploads/${photo.filename}` : null;
  const client = await pool.connect();
  try {
    await client.query('BEGIN');
    await client.query(
      'INSERT INTO students (name) VALUES ($1) ON CONFLICT (name) DO NOTHING',
      [student_name.trim()]
    );
    const { rows } = await client.query(
      `INSERT INTO entries (student_name, group_id, description, photo_path)
       VALUES ($1, $2, $3, $4) RETURNING *`,
      [student_name.trim(), gid, description.trim(), photo_path]
    );
    for (const f of projectFiles) {
      const token = crypto.randomBytes(16).toString('hex');
      await client.query(
        'INSERT INTO project_files (entry_id, token, path, name) VALUES ($1, $2, $3, $4)',
        [rows[0].id, token, `/uploads/${f.filename}`, f.originalname]
      );
    }
    await client.query('COMMIT');
    res.status(201).json({ ...rows[0], files: projectFiles.length });
  } catch (e) {
    await client.query('ROLLBACK').catch(() => {});
    removeUpload(photo);
    projectFiles.forEach(removeUpload);
    console.error('POST /api/entries:', e);
    res.status(500).json({ error: e.message });
  } finally {
    client.release();
  }
});

app.put('/api/entries/:id', requireAdmin, async (req, res) => {
  const { student_name, group_id, description } = req.body;
  const { rows } = await pool.query(
    `UPDATE entries SET
      student_name = COALESCE($1, student_name),
      group_id = COALESCE($2, group_id),
      description = COALESCE($3, description)
     WHERE id = $4 RETURNING *`,
    [
      student_name ? student_name.trim() : null,
      group_id || null,
      description ? description.trim() : null,
      req.params.id,
    ]
  );
  if (!rows.length) return res.status(404).json({ error: 'Not found' });
  res.json(rows[0]);
});

app.delete('/api/entries/:id', requireAdmin, async (req, res) => {
  await pool.query('UPDATE entries SET deleted_at = now() WHERE id = $1', [req.params.id]);
  res.json({ ok: true });
});

app.put('/api/entries/:id/restore', requireAdmin, async (req, res) => {
  await pool.query('UPDATE entries SET deleted_at = NULL WHERE id = $1', [req.params.id]);
  res.json({ ok: true });
});

app.delete('/api/entries/:id/permanent', requireAdmin, async (req, res) => {
  await removeEntryFiles(req.params.id);
  await pool.query('DELETE FROM entries WHERE id = $1', [req.params.id]);
  res.json({ ok: true });
});

app.get('/api/trash', requireAdmin, async (req, res) => {
  const { limit, offset } = req.query;
  const { rows: crows } = await pool.query(
    "SELECT count(*)::int AS n FROM entries WHERE deleted_at IS NOT NULL"
  );
  const total = crows[0].n;
  let q = `SELECT e.*, g.name AS group_name FROM entries e
           JOIN groups g ON g.id = e.group_id
           WHERE e.deleted_at IS NOT NULL ORDER BY e.deleted_at DESC`;
  const qparams = [];
  const lim = parseInt(limit, 10);
  if (lim > 0) { qparams.push(lim); q += ` LIMIT $${qparams.length}`; }
  const off = parseInt(offset, 10);
  if (off > 0) { qparams.push(off); q += ` OFFSET $${qparams.length}`; }
  const { rows } = await pool.query(q, qparams);
  let files = {};
  if (rows.length) {
    const fRes = await pool.query(
      'SELECT id, entry_id, token, name FROM project_files WHERE entry_id = ANY($1) ORDER BY id',
      [rows.map(r => r.id)]
    );
    fRes.rows.forEach(f => { (files[f.entry_id] = files[f.entry_id] || []).push(f); });
  }
  rows.forEach(r => { r.files = files[r.id] || []; });
  res.json({ entries: rows, total });
});

app.delete('/api/trash', requireAdmin, async (req, res) => {
  const { rows } = await pool.query(
    `SELECT photo_path AS p FROM entries WHERE deleted_at IS NOT NULL
     UNION ALL
     SELECT pf.path AS p FROM project_files pf
     JOIN entries e ON e.id = pf.entry_id WHERE e.deleted_at IS NOT NULL`
  );
  rows.forEach(r => safeUnlink(r.p));
  const d = await pool.query('DELETE FROM entries WHERE deleted_at IS NOT NULL');
  res.json({ ok: true, deleted: d.rowCount });
});

// --- Error handlers ---
const ERROR_HTML = fs.readFileSync(path.join(__dirname, 'public', 'error.html'), 'utf8');

function isApiRoute(req) {
  return req.path.startsWith('/api/') || req.path.startsWith('/s/');
}

function escapeHtml(str) {
  return String(str).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;').replace(/'/g, '&#039;');
}

function renderErrorPage(code, title, message, details) {
  return ERROR_HTML
    .replace('id="errorCode">404', `id="errorCode">${code}`)
    .replace('id="errorTitle">Страница не найдена', `id="errorTitle">${title}`)
    .replace('id="errorMessage">Запрашиваемая страница не существует или была перемещена.', `id="errorMessage">${message}`)
    .replace('style="display:none"', details ? '' : 'style="display:none"')
    .replace('<pre id="errorStack"></pre>', details ? `<pre id="errorStack">${escapeHtml(details)}</pre>` : '<pre id="errorStack"></pre>');
}

app.use((req, res, next) => {
  if (isApiRoute(req)) {
    return res.status(404).json({ error: 'Not found' });
  }
  res.status(404).send(renderErrorPage(404, 'Страница не найдена', 'Запрашиваемая страница не существует или была перемещена.'));
});

app.use((err, req, res, next) => {
  console.error('Error:', err);
  if (isApiRoute(req)) {
    return res.status(500).json({ error: 'Internal server error' });
  }
  const msg = process.env.NODE_ENV === 'production' ? 'Произошла ошибка на сервере.' : (err?.message || 'Internal server error');
  const details = process.env.NODE_ENV === 'production' ? '' : (err?.stack || '');
  res.status(500).send(renderErrorPage(500, 'Ошибка сервера', msg, details));
});

const PORT = process.env.PORT || 3000;
const HTTPS_PORT = process.env.HTTPS_PORT || 3443;

process.on('unhandledRejection', (err) => { console.error('Unhandled rejection:', err); });
process.on('uncaughtException', (err) => { console.error('Uncaught exception:', err); });

const certPath = path.join(__dirname, 'certs', 'cert.pem');
const keyPath = path.join(__dirname, 'certs', 'key.pem');

const redirect = express();
redirect.use((req, res) => {
  res.redirect(301, `https://${req.headers.host.split(':')[0]}:${HTTPS_PORT}${req.originalUrl}`);
});
redirect.listen(PORT, '0.0.0.0', () => console.log(`HTTP  : ${PORT} (redirect → HTTPS)`));

if (fs.existsSync(certPath) && fs.existsSync(keyPath)) {
  https.createServer({ key: fs.readFileSync(keyPath), cert: fs.readFileSync(certPath) }, app)
    .listen(HTTPS_PORT, '0.0.0.0', () => console.log(`HTTPS : ${HTTPS_PORT}`));
} else {
  console.log('HTTPS: no certs found, skipping');
}

sweepOrphanedUploads().catch(err => console.error('Upload sweep:', err));