const router = require('express').Router();

const timer = (time = 300) => (req, res, next) => setTimeout(next, time);

router.use(timer());

// In-memory storage for demo
const users = [];
const cigarettes = [];
let userIdCounter = 1;
let cigaretteIdCounter = 1;

// Simple token generation (for demo purposes only)
const generateToken = (userId) => {
  return Buffer.from(JSON.stringify({ userId, exp: Date.now() + 12 * 60 * 60 * 1000 })).toString('base64');
};

const verifyToken = (token) => {
  try {
    const payload = JSON.parse(Buffer.from(token, 'base64').toString());
    if (payload.exp > Date.now()) {
      return payload.userId;
    }
    return null;
  } catch {
    return null;
  }
};

// Auth middleware
const authMiddleware = (req, res, next) => {
  const authHeader = req.headers.authorization;
  if (!authHeader || !authHeader.startsWith('Bearer ')) {
    return res.status(401).json({ success: false, errors: 'Требуется авторизация' });
  }

  const token = authHeader.substring(7);
  const userId = verifyToken(token);
  
  if (!userId) {
    return res.status(401).json({ success: false, errors: 'Неверный или истекший токен авторизации' });
  }

  req.userId = userId;
  next();
};

// POST /auth/signup
router.post('/auth/signup', (req, res) => {
  const { login, password } = req.body;

  if (!login || !password) {
    return res.status(400).json({
      success: false,
      errors: 'Не все поля заполнены: login, password'
    });
  }

  const existingUser = users.find(u => u.login === login);
  if (existingUser) {
    return res.status(500).json({
      success: false,
      errors: 'Пользователь с таким логином уже существует'
    });
  }

  const user = {
    id: String(userIdCounter++),
    login,
    password, // In real app, hash this!
    created: new Date().toISOString()
  };

  users.push(user);

  res.json({
    success: true,
    body: { ok: true }
  });
});

// POST /auth/signin
router.post('/auth/signin', (req, res) => {
  const { login, password } = req.body;

  if (!login || !password) {
    return res.status(400).json({
      success: false,
      errors: 'Не все поля заполнены: login, password'
    });
  }

  const user = users.find(u => u.login === login && u.password === password);
  
  if (!user) {
    return res.status(500).json({
      success: false,
      errors: 'Неверный логин или пароль'
    });
  }

  const token = generateToken(user.id);

  res.json({
    success: true,
    body: {
      user: {
        id: user.id,
        login: user.login,
        created: user.created
      },
      token
    }
  });
});

// POST /cigarettes
router.post('/cigarettes', authMiddleware, (req, res) => {
  const { smokedAt, note } = req.body;
  
  const cigarette = {
    id: String(cigaretteIdCounter++),
    userId: req.userId,
    smokedAt: smokedAt || new Date().toISOString(),
    note: note || '',
    created: new Date().toISOString()
  };

  cigarettes.push(cigarette);

  res.json({
    success: true,
    body: cigarette
  });
});

// GET /cigarettes
router.get('/cigarettes', authMiddleware, (req, res) => {
  const { from, to } = req.query;
  
  let userCigarettes = cigarettes.filter(c => c.userId === req.userId);

  if (from) {
    const fromDate = new Date(from);
    userCigarettes = userCigarettes.filter(c => new Date(c.smokedAt) >= fromDate);
  }

  if (to) {
    const toDate = new Date(to);
    userCigarettes = userCigarettes.filter(c => new Date(c.smokedAt) <= toDate);
  }

  // Sort by smokedAt (oldest to newest)
  userCigarettes.sort((a, b) => new Date(a.smokedAt).getTime() - new Date(b.smokedAt).getTime());

  res.json({
    success: true,
    body: userCigarettes
  });
});

// GET /stats/daily
router.get('/stats/daily', authMiddleware, (req, res) => {
  const { from, to } = req.query;
  
  // Default: 30 days ago to now
  const fromDate = from ? new Date(from) : new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
  const toDate = to ? new Date(to) : new Date();

  let userCigarettes = cigarettes.filter(c => {
    if (c.userId !== req.userId) return false;
    const smokedDate = new Date(c.smokedAt);
    return smokedDate >= fromDate && smokedDate <= toDate;
  });

  // Group by date
  const dailyStats = {};
  userCigarettes.forEach(c => {
    const date = c.smokedAt.split('T')[0]; // YYYY-MM-DD
    dailyStats[date] = (dailyStats[date] || 0) + 1;
  });

  // Convert to array and sort
  const result = Object.entries(dailyStats)
    .map(([date, count]) => ({ date, count }))
    .sort((a, b) => a.date.localeCompare(b.date));

  res.json({
    success: true,
    body: result
  });
});

module.exports = router;