const express = require('express');
const { Pool, types } = require('pg');
const multer = require('multer');
const cors = require('cors');
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 ADMIN_PASSWORD = process.env.ADMIN_PASSWORD || 'admin';

app.use(cors());
app.use(express.json());
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();
}

const upload = multer({
  storage: multer.diskStorage({
    destination: (_, __, cb) => {
      fs.mkdirSync('uploads', { recursive: true });
      cb(null, 'uploads');
    },
    filename: (_, file, cb) => {
      const ext = path.extname(file.originalname) || '.jpg';
      cb(null, `${Date.now()}-${Math.random().toString(36).slice(2, 8)}${ext}`);
    },
  }),
  limits: { fileSize: 10 * 1024 * 1024 },
  fileFilter: (_, file, cb) => {
    if (file.mimetype.startsWith('image/')) cb(null, true);
    else cb(new Error('Only images'));
  },
});

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;
}

function removeUpload(file) {
  if (!file) return;
  const fp = path.join(__dirname, file.path);
  if (fs.existsSync(fp)) fs.unlinkSync(fp);
}

// --- 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.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 tar = require('tar');
const os = require('os');
const uploadBackup = multer({
  storage: multer.memoryStorage(),
  limits: { fileSize: 300 * 1024 * 1024 },
});

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

app.get('/api/backup', requireAdmin, async (_, res) => {
  const staging = fs.mkdtempSync(path.join(os.tmpdir(), 'wido-bk-'));
  try {
    const [g, s, e, st] = 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'),
    ]);
    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 };
    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 });
  }
});

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 gunz = await gunzipAsync(req.file.buffer).catch(() => null);
    if (gunz && gunz[0] === 0x7b) {
      data = JSON.parse(gunz.toString('utf8'));
      legacyPhotos = data.photos || [];
    } else {
      const inPath = path.join(staging, 'input.tar.gz');
      fs.writeFileSync(inPath, req.file.buffer);
      await tar.x({ file: inPath, cwd: staging });
      data = JSON.parse(fs.readFileSync(path.join(staging, 'data.json'), 'utf8'));
    }
  } catch {
    fs.rmSync(staging, { recursive: true, force: true });
    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 });
    return res.status(400).json({ error: 'Неверный формат бэкапа' });
  }
  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 data.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 ?? null, x.time_start ?? null, x.time_end ?? null]
      );
    }
    for (const x of data.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 ?? null]
      );
    }
    for (const x of data.entries) {
      await client.query(
        'INSERT INTO entries (id, student_name, group_id, description, photo_path, created_at) VALUES ($1,$2,$3,$4,$5,$6)',
        [x.id, x.student_name, x.group_id, x.description, x.photo_path ?? null, x.created_at]
      );
    }
    for (const [k, v] of Object.entries(data.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']) {
      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 });
    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 });
  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 } = req.body;
  if (!name?.trim()) return res.status(400).json({ error: 'Название обязательно' });
  const token = crypto.randomBytes(20).toString('hex');
  const { rows } = await pool.query(
    `INSERT INTO share_links (token, name, group_id, student_name, date_from, date_to)
     VALUES ($1, $2, $3, $4, $5, $6) RETURNING *`,
    [token, name.trim(), group_id || null, student_name || null, date_from || null, date_to || null]
  );
  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 } = req.body;
  if (!name?.trim()) return res.status(400).json({ error: 'Название обязательно' });
  const { rows } = await pool.query(
    `UPDATE share_links SET
       name = $1, group_id = $2, student_name = $3, date_from = $4, date_to = $5
     WHERE id = $6 RETURNING *`,
    [name.trim(), group_id || null, student_name || null, date_from || null, date_to || null, req.params.id]
  );
  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', 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];
  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')`); }
  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
  );
  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,
    entries,
  });
});

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

// --- Groups CRUD ---
app.get('/api/groups', async (_, res) => {
  const { rows } = await pool.query('SELECT * FROM groups ORDER BY id');
  res.json(rows);
});

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

// --- Students CRUD ---
app.get('/api/students', 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 } = req.query;
  const conditions = [];
  const params = [];
  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);
  res.json({ entries: rows, total });
});

app.get('/api/stats', requireAdmin, async (_, res) => {
  const [entries, groups, students, today] = await Promise.all([
    pool.query('SELECT count(*)::int AS n FROM entries'),
    pool.query('SELECT count(*)::int AS n FROM groups'),
    pool.query('SELECT count(DISTINCT student_name)::int AS n FROM entries'),
    pool.query("SELECT count(*)::int AS n FROM entries WHERE created_at >= now()::date"),
  ]);
  res.json({
    entries: entries.rows[0].n,
    groups: groups.rows[0].n,
    students: students.rows[0].n,
    today: today.rows[0].n,
  });
});

app.post('/api/entries', upload.single('photo'), async (req, res) => {
  const { student_name, group_id, description } = req.body;
  if (!student_name?.trim() || !group_id || !description?.trim()) {
    removeUpload(req.file);
    return res.status(400).json({ error: 'All fields required' });
  }
  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(req.file);
      return res.status(429).json({ error: `Уже ответили: подождите ${intervalMin} минут` });
    }
  }
  const photo_path = req.file ? `/uploads/${req.file.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(), group_id, description.trim(), photo_path]
    );
    await client.query('COMMIT');
    res.status(201).json(rows[0]);
  } catch (e) {
    await client.query('ROLLBACK');
    throw e;
  } 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) => {
  const { rows } = await pool.query(
    'DELETE FROM entries WHERE id = $1 RETURNING photo_path',
    [req.params.id]
  );
  if (rows[0]?.photo_path) {
    const fp = path.join(__dirname, rows[0].photo_path);
    if (fs.existsSync(fp)) fs.unlinkSync(fp);
  }
  res.json({ ok: true });
});

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

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');
}