const pool = require('../db/connection');

const getReservations = async (req, res) => {
  try {
    const { status, from_date, to_date, search } = req.query;
    let query = `
      SELECT r.*, g.first_name, g.last_name, g.phone, g.email,
             rm.room_number, rm.room_type
      FROM reservations r
      JOIN guests g ON g.id = r.guest_id
      LEFT JOIN rooms rm ON rm.id = r.room_id
      WHERE 1=1
    `;
    const params = [];
    let paramIndex = 1;

    if (status && status !== 'all') {
      query += ` AND r.status = $${paramIndex++}`;
      params.push(status);
    }
    if (from_date) {
      query += ` AND r.check_in >= $${paramIndex++}`;
      params.push(from_date);
    }
    if (to_date) {
      query += ` AND r.check_out <= $${paramIndex++}`;
      params.push(to_date);
    }
    if (search) {
      query += ` AND (g.first_name ILIKE $${paramIndex} OR g.last_name ILIKE $${paramIndex})`;
      params.push(`%${search}%`);
      paramIndex++;
    }
    query += ' ORDER BY r.created_at DESC LIMIT 100';

    const result = await pool.query(query, params);
    res.json({ reservations: result.rows });
  } catch (error) {
    console.error(error);
    res.status(500).json({ message: 'Error al obtener reservaciones' });
  }
};

const createReservation = async (req, res) => {
  try {
    const { room_id, guest_id, guest, check_in, check_out, channel, total_amount, adults, children, notes } = req.body;
    const created_by = req.user?.user_id;

    // Create guest if new
    let finalGuestId = guest_id;
    if (!finalGuestId && guest) {
      const guestResult = await pool.query(
        'INSERT INTO guests (first_name, last_name, email, phone, nationality) VALUES ($1, $2, $3, $4, $5) RETURNING id',
        [guest.first_name, guest.last_name, guest.email || null, guest.phone || null, guest.nationality || null]
      );
      finalGuestId = guestResult.rows[0].id;
    }

    // Check availability
    const overlap = await pool.query(
      `SELECT id FROM reservations
       WHERE room_id = $1 AND status IN ('confirmed', 'checked_in')
       AND check_in < $3 AND check_out > $2`,
      [room_id, check_in, check_out]
    );
    if (overlap.rows.length > 0) {
      return res.status(409).json({ message: 'La habitacion no esta disponible para esas fechas' });
    }

    const result = await pool.query(
      `INSERT INTO reservations (room_id, guest_id, check_in, check_out, status, channel, total_amount, adults, children, notes, created_by)
       VALUES ($1, $2, $3, $4, 'pending', $5, $6, $7, $8, $9, $10) RETURNING *`,
      [room_id, finalGuestId, check_in, check_out, channel || 'direct', total_amount, adults || 1, children || 0, notes, created_by]
    );

    res.status(201).json({ reservation: result.rows[0], message: 'Reservacion creada correctamente' });
  } catch (error) {
    console.error(error);
    res.status(500).json({ message: 'Error al crear reservacion' });
  }
};

const updateReservation = async (req, res) => {
  try {
    const { id } = req.params;
    const { room_id, check_in, check_out, channel, total_amount, adults, children, notes } = req.body;

    const result = await pool.query(
      `UPDATE reservations SET room_id = COALESCE($1, room_id), check_in = COALESCE($2, check_in),
       check_out = COALESCE($3, check_out), channel = COALESCE($4, channel),
       total_amount = COALESCE($5, total_amount), adults = COALESCE($6, adults),
       children = COALESCE($7, children), notes = COALESCE($8, notes), updated_at = NOW()
       WHERE id = $9 RETURNING *`,
      [room_id, check_in, check_out, channel, total_amount, adults, children, notes, id]
    );

    if (result.rows.length === 0) return res.status(404).json({ message: 'Reservacion no encontrada' });
    res.json({ reservation: result.rows[0] });
  } catch (error) {
    console.error(error);
    res.status(500).json({ message: 'Error al actualizar reservacion' });
  }
};

const updateReservationStatus = async (req, res) => {
  try {
    const { id } = req.params;
    const { status } = req.body;
    const userId = req.user?.user_id;

    const current = await pool.query('SELECT * FROM reservations WHERE id = $1', [id]);
    if (current.rows.length === 0) return res.status(404).json({ message: 'Reservacion no encontrada' });

    const reservation = current.rows[0];
    const validTransitions = {
      pending: ['confirmed', 'cancelled'],
      confirmed: ['checked_in', 'cancelled'],
      checked_in: ['checked_out'],
    };

    const allowed = validTransitions[reservation.status];
    if (!allowed || !allowed.includes(status)) {
      return res.status(400).json({ message: `No se puede cambiar de ${reservation.status} a ${status}` });
    }

    await pool.query('UPDATE reservations SET status = $1, updated_at = NOW() WHERE id = $2', [status, id]);

    // Cascading side effects
    if (status === 'checked_in') {
      // Set room to occupied
      await pool.query("UPDATE rooms SET status = 'occupied' WHERE id = $1", [reservation.room_id]);
      await pool.query(
        'INSERT INTO room_status_log (room_id, previous_status, new_status, changed_by) VALUES ($1, $2, $3, $4)',
        [reservation.room_id, 'available', 'occupied', userId]
      );
      // Create guest stay record
      await pool.query(
        'INSERT INTO guest_stays (guest_id, reservation_id, room_id, check_in) VALUES ($1, $2, $3, NOW())',
        [reservation.guest_id, reservation.id, reservation.room_id]
      );
    }

    if (status === 'checked_out') {
      // Set room to cleaning
      await pool.query("UPDATE rooms SET status = 'cleaning' WHERE id = $1", [reservation.room_id]);
      await pool.query(
        'INSERT INTO room_status_log (room_id, previous_status, new_status, changed_by) VALUES ($1, $2, $3, $4)',
        [reservation.room_id, 'occupied', 'cleaning', userId]
      );
      // Create housekeeping task
      await pool.query(
        `INSERT INTO housekeeping_tasks (room_id, priority, type, status) VALUES ($1, 'high', 'checkout', 'pending')`,
        [reservation.room_id]
      );
      // Close guest stay
      await pool.query(
        'UPDATE guest_stays SET check_out = NOW(), total_charged = $1 WHERE reservation_id = $2 AND check_out IS NULL',
        [reservation.total_amount, reservation.id]
      );
    }

    if (status === 'cancelled') {
      // Free room if it was occupied
      if (reservation.status === 'checked_in') {
        await pool.query("UPDATE rooms SET status = 'available' WHERE id = $1", [reservation.room_id]);
      }
    }

    res.json({ message: 'Estado de reservacion actualizado' });
  } catch (error) {
    console.error(error);
    res.status(500).json({ message: 'Error al actualizar estado' });
  }
};

const checkAvailability = async (req, res) => {
  try {
    const { room_id, check_in, check_out } = req.query;
    const overlap = await pool.query(
      `SELECT id FROM reservations WHERE room_id = $1 AND status IN ('confirmed', 'checked_in')
       AND check_in < $3 AND check_out > $2`,
      [room_id, check_in, check_out]
    );
    res.json({ available: overlap.rows.length === 0 });
  } catch (error) {
    console.error(error);
    res.status(500).json({ message: 'Error al verificar disponibilidad' });
  }
};

module.exports = { getReservations, createReservation, updateReservation, updateReservationStatus, checkAvailability };