const express = require('express');
const cors = require('cors');
const { Pool } = require('pg');
const bcrypt = require('bcryptjs');
const jwt = require('jsonwebtoken');
const { v4: uuidv4 } = require('uuid');
const path = require('path');

const app = express();
const PORT = process.env.PORT || 3000;
const JWT_SECRET = process.env.JWT_SECRET || 'airewit-secret-key-change-in-prod';

const pool = new Pool({
  connectionString: process.env.DATABASE_URL || 'postgresql://postgres:postgres@postgres:5432/airewit',
});

app.use(cors());
app.use(express.json());
app.use(express.static(path.join(__dirname, 'client/dist')));

// Initialize DB tables
async function initDB() {
  const client = await pool.connect();
  try {
    await client.query(`
      CREATE EXTENSION IF NOT EXISTS "pgcrypto";

      CREATE TABLE IF NOT EXISTS users (
        id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
        email VARCHAR(255) UNIQUE NOT NULL,
        name VARCHAR(100) NOT NULL,
        password_hash VARCHAR(255) NOT NULL,
        created_at TIMESTAMP DEFAULT NOW()
      );

      CREATE TABLE IF NOT EXISTS events (
        id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
        user_id UUID REFERENCES users(id) ON DELETE CASCADE,
        title VARCHAR(255) NOT NULL,
        description TEXT,
        event_date TIMESTAMP NOT NULL,
        location VARCHAR(255),
        max_participants INTEGER,
        budget DECIMAL(10,2) DEFAULT 0,
        created_at TIMESTAMP DEFAULT NOW(),
        updated_at TIMESTAMP DEFAULT NOW()
      );

      CREATE TABLE IF NOT EXISTS participants (
        id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
        event_id UUID REFERENCES events(id) ON DELETE CASCADE,
        name VARCHAR(100) NOT NULL,
        email VARCHAR(255) NOT NULL,
        phone VARCHAR(50),
        status VARCHAR(50) DEFAULT 'invited',
        created_at TIMESTAMP DEFAULT NOW(),
        updated_at TIMESTAMP DEFAULT NOW()
      );

      CREATE TABLE IF NOT EXISTS budget_items (
        id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
        event_id UUID REFERENCES events(id) ON DELETE CASCADE,
        title VARCHAR(255) NOT NULL,
        type VARCHAR(20) NOT NULL CHECK (type IN ('income', 'expense')),
        amount DECIMAL(10,2) NOT NULL,
        description TEXT,
        created_at TIMESTAMP DEFAULT NOW(),
        updated_at TIMESTAMP DEFAULT NOW()
      );

      CREATE INDEX IF NOT EXISTS idx_events_user_id ON events(user_id);
      CREATE INDEX IF NOT EXISTS idx_participants_event_id ON participants(event_id);
      CREATE INDEX IF NOT EXISTS idx_budget_items_event_id ON budget_items(event_id);
    `);
    console.log('Database initialized');
  } catch (err) {
    console.error('DB init error:', err.message);
  } finally {
    client.release();
  }
}

// Auth middleware
function authMiddleware(req, res, next) {
  const token = req.headers.authorization?.replace('Bearer ', '');
  if (!token) return res.status(401).json({ error: 'Unauthorized' });
  try {
    req.user = jwt.verify(token, JWT_SECRET);
    next();
  } catch {
    res.status(401).json({ error: 'Invalid token' });
  }
}

// Health check
app.get('/health', async (req, res) => {
  let dbOk = false;
  try {
    await pool.query('SELECT 1');
    dbOk = true;
  } catch {}
  res.json({
    status: 'ok',
    commit: process.env.GIT_COMMIT || 'unknown',
    db: dbOk ? 'connected' : 'error',
    timestamp: new Date().toISOString()
  });
});

// ========== AUTH ==========

app.post('/api/auth/register', async (req, res) => {
  const { email, name, password } = req.body;
  if (!email || !name || !password) return res.status(400).json({ error: 'Missing fields' });
  try {
    const hash = await bcrypt.hash(password, 10);
    const result = await pool.query(
      'INSERT INTO users (email, name, password_hash) VALUES ($1, $2, $3) RETURNING id, email, name, created_at',
      [email, name, hash]
    );
    const user = result.rows[0];
    const token = jwt.sign({ userId: user.id, email: user.email }, JWT_SECRET, { expiresIn: '7d' });
    res.status(201).json({ user, token });
  } catch (err) {
    if (err.code === '23505') return res.status(409).json({ error: 'Email already exists' });
    res.status(500).json({ error: 'Server error' });
  }
});

app.post('/api/auth/login', async (req, res) => {
  const { email, password } = req.body;
  if (!email || !password) return res.status(400).json({ error: 'Missing fields' });
  try {
    const result = await pool.query('SELECT * FROM users WHERE email = $1', [email]);
    const user = result.rows[0];
    if (!user) return res.status(401).json({ error: 'Invalid credentials' });
    const valid = await bcrypt.compare(password, user.password_hash);
    if (!valid) return res.status(401).json({ error: 'Invalid credentials' });
    const token = jwt.sign({ userId: user.id, email: user.email }, JWT_SECRET, { expiresIn: '7d' });
    res.json({ user: { id: user.id, email: user.email, name: user.name }, token });
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.get('/api/auth/me', authMiddleware, async (req, res) => {
  try {
    const result = await pool.query('SELECT id, email, name, created_at FROM users WHERE id = $1', [req.user.userId]);
    if (!result.rows[0]) return res.status(404).json({ error: 'User not found' });
    res.json(result.rows[0]);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

// ========== EVENTS ==========

app.get('/api/events', authMiddleware, async (req, res) => {
  try {
    const result = await pool.query(
      `SELECT e.*,
        COUNT(DISTINCT p.id) AS participant_count,
        COALESCE(SUM(CASE WHEN bi.type='income' THEN bi.amount ELSE 0 END), 0) AS total_income,
        COALESCE(SUM(CASE WHEN bi.type='expense' THEN bi.amount ELSE 0 END), 0) AS total_expenses
      FROM events e
      LEFT JOIN participants p ON p.event_id = e.id
      LEFT JOIN budget_items bi ON bi.event_id = e.id
      WHERE e.user_id = $1
      GROUP BY e.id
      ORDER BY e.event_date ASC`,
      [req.user.userId]
    );
    res.json(result.rows);
  } catch (err) {
    res.status(500).json({ error: 'Server error' });
  }
});

app.get('/api/events/:id', authMiddleware, async (req, res) => {
  try {
    const result = await pool.query(
      'SELECT * FROM events WHERE id = $1 AND user_id = $2',
      [req.params.id, req.user.userId]
    );
    if (!result.rows[0]) return res.status(404).json({ error: 'Event not found' });
    res.json(result.rows[0]);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.post('/api/events', authMiddleware, async (req, res) => {
  const { title, description, event_date, location, max_participants, budget } = req.body;
  if (!title || !event_date) return res.status(400).json({ error: 'Title and event_date are required' });
  try {
    const result = await pool.query(
      `INSERT INTO events (user_id, title, description, event_date, location, max_participants, budget)
       VALUES ($1,$2,$3,$4,$5,$6,$7) RETURNING *`,
      [req.user.userId, title, description, event_date, location, max_participants || null, budget || 0]
    );
    res.status(201).json(result.rows[0]);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.put('/api/events/:id', authMiddleware, async (req, res) => {
  const { title, description, event_date, location, max_participants, budget } = req.body;
  if (!title || !event_date) return res.status(400).json({ error: 'Title and event_date are required' });
  try {
    const result = await pool.query(
      `UPDATE events SET title=$1, description=$2, event_date=$3, location=$4,
       max_participants=$5, budget=$6, updated_at=NOW()
       WHERE id=$7 AND user_id=$8 RETURNING *`,
      [title, description, event_date, location, max_participants || null, budget || 0, req.params.id, req.user.userId]
    );
    if (!result.rows[0]) return res.status(404).json({ error: 'Event not found' });
    res.json(result.rows[0]);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.delete('/api/events/:id', authMiddleware, async (req, res) => {
  try {
    const result = await pool.query(
      'DELETE FROM events WHERE id=$1 AND user_id=$2 RETURNING id',
      [req.params.id, req.user.userId]
    );
    if (!result.rows[0]) return res.status(404).json({ error: 'Event not found' });
    res.json({ success: true });
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

// ========== PARTICIPANTS ==========

app.get('/api/events/:eventId/participants', authMiddleware, async (req, res) => {
  try {
    // Verify event belongs to user
    const ev = await pool.query('SELECT id FROM events WHERE id=$1 AND user_id=$2', [req.params.eventId, req.user.userId]);
    if (!ev.rows[0]) return res.status(404).json({ error: 'Event not found' });
    const result = await pool.query(
      'SELECT * FROM participants WHERE event_id=$1 ORDER BY created_at ASC',
      [req.params.eventId]
    );
    res.json(result.rows);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.post('/api/events/:eventId/participants', authMiddleware, async (req, res) => {
  const { name, email, phone, status } = req.body;
  if (!name || !email) return res.status(400).json({ error: 'Name and email are required' });
  try {
    const ev = await pool.query('SELECT id FROM events WHERE id=$1 AND user_id=$2', [req.params.eventId, req.user.userId]);
    if (!ev.rows[0]) return res.status(404).json({ error: 'Event not found' });
    const result = await pool.query(
      'INSERT INTO participants (event_id, name, email, phone, status) VALUES ($1,$2,$3,$4,$5) RETURNING *',
      [req.params.eventId, name, email, phone || null, status || 'invited']
    );
    res.status(201).json(result.rows[0]);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.put('/api/events/:eventId/participants/:id', authMiddleware, async (req, res) => {
  const { name, email, phone, status } = req.body;
  if (!name || !email) return res.status(400).json({ error: 'Name and email are required' });
  try {
    const ev = await pool.query('SELECT id FROM events WHERE id=$1 AND user_id=$2', [req.params.eventId, req.user.userId]);
    if (!ev.rows[0]) return res.status(404).json({ error: 'Event not found' });
    const result = await pool.query(
      `UPDATE participants SET name=$1, email=$2, phone=$3, status=$4, updated_at=NOW()
       WHERE id=$5 AND event_id=$6 RETURNING *`,
      [name, email, phone || null, status || 'invited', req.params.id, req.params.eventId]
    );
    if (!result.rows[0]) return res.status(404).json({ error: 'Participant not found' });
    res.json(result.rows[0]);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.delete('/api/events/:eventId/participants/:id', authMiddleware, async (req, res) => {
  try {
    const ev = await pool.query('SELECT id FROM events WHERE id=$1 AND user_id=$2', [req.params.eventId, req.user.userId]);
    if (!ev.rows[0]) return res.status(404).json({ error: 'Event not found' });
    const result = await pool.query(
      'DELETE FROM participants WHERE id=$1 AND event_id=$2 RETURNING id',
      [req.params.id, req.params.eventId]
    );
    if (!result.rows[0]) return res.status(404).json({ error: 'Participant not found' });
    res.json({ success: true });
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

// ========== BUDGET ITEMS ==========

app.get('/api/events/:eventId/budget', authMiddleware, async (req, res) => {
  try {
    const ev = await pool.query('SELECT id FROM events WHERE id=$1 AND user_id=$2', [req.params.eventId, req.user.userId]);
    if (!ev.rows[0]) return res.status(404).json({ error: 'Event not found' });
    const result = await pool.query(
      'SELECT * FROM budget_items WHERE event_id=$1 ORDER BY created_at ASC',
      [req.params.eventId]
    );
    res.json(result.rows);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.post('/api/events/:eventId/budget', authMiddleware, async (req, res) => {
  const { title, type, amount, description } = req.body;
  if (!title || !type || !amount) return res.status(400).json({ error: 'Title, type, and amount are required' });
  if (!['income', 'expense'].includes(type)) return res.status(400).json({ error: 'Type must be income or expense' });
  try {
    const ev = await pool.query('SELECT id FROM events WHERE id=$1 AND user_id=$2', [req.params.eventId, req.user.userId]);
    if (!ev.rows[0]) return res.status(404).json({ error: 'Event not found' });
    const result = await pool.query(
      'INSERT INTO budget_items (event_id, title, type, amount, description) VALUES ($1,$2,$3,$4,$5) RETURNING *',
      [req.params.eventId, title, type, amount, description || null]
    );
    res.status(201).json(result.rows[0]);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.put('/api/events/:eventId/budget/:id', authMiddleware, async (req, res) => {
  const { title, type, amount, description } = req.body;
  if (!title || !type || !amount) return res.status(400).json({ error: 'Title, type, and amount are required' });
  if (!['income', 'expense'].includes(type)) return res.status(400).json({ error: 'Type must be income or expense' });
  try {
    const ev = await pool.query('SELECT id FROM events WHERE id=$1 AND user_id=$2', [req.params.eventId, req.user.userId]);
    if (!ev.rows[0]) return res.status(404).json({ error: 'Event not found' });
    const result = await pool.query(
      `UPDATE budget_items SET title=$1, type=$2, amount=$3, description=$4, updated_at=NOW()
       WHERE id=$5 AND event_id=$6 RETURNING *`,
      [title, type, amount, description || null, req.params.id, req.params.eventId]
    );
    if (!result.rows[0]) return res.status(404).json({ error: 'Budget item not found' });
    res.json(result.rows[0]);
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

app.delete('/api/events/:eventId/budget/:id', authMiddleware, async (req, res) => {
  try {
    const ev = await pool.query('SELECT id FROM events WHERE id=$1 AND user_id=$2', [req.params.eventId, req.user.userId]);
    if (!ev.rows[0]) return res.status(404).json({ error: 'Event not found' });
    const result = await pool.query(
      'DELETE FROM budget_items WHERE id=$1 AND event_id=$2 RETURNING id',
      [req.params.id, req.params.eventId]
    );
    if (!result.rows[0]) return res.status(404).json({ error: 'Budget item not found' });
    res.json({ success: true });
  } catch {
    res.status(500).json({ error: 'Server error' });
  }
});

// SPA fallback
app.get('*', (req, res) => {
  res.sendFile(path.join(__dirname, 'client/dist/index.html'));
});

app.listen(PORT, async () => {
  console.log(`Server running on port ${PORT}`);
  await initDB();
});