const express = require('express');
const cors = require('cors');
const Database = require('better-sqlite3');
const path = require('path');

const app = express();
const PORT = process.env.PORT || 3000;
const API_KEY = process.env.API_KEY || null;
const ALLOWED_ORIGINS = (process.env.ALLOWED_ORIGINS || 'https://chatlabsai.com').split(',');

// Initialize SQLite database
const dbPath = process.env.DATABASE_PATH || path.join(__dirname, 'data', 'forms.db');
const db = new Database(dbPath);

// Create tables
db.exec(`
  CREATE TABLE IF NOT EXISTS submissions (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    form_name TEXT NOT NULL,
    email TEXT NOT NULL,
    source TEXT,
    ip TEXT,
    user_agent TEXT,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );
  CREATE INDEX IF NOT EXISTS idx_form_name ON submissions(form_name);
  CREATE INDEX IF NOT EXISTS idx_email ON submissions(email);
  CREATE INDEX IF NOT EXISTS idx_created_at ON submissions(created_at);
`);

// Middleware
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(cors({
  origin: (origin, callback) => {
    // Allow requests with no origin (mobile apps, curl, etc.)
    if (!origin) return callback(null, true);
    if (ALLOWED_ORIGINS.includes(origin) || ALLOWED_ORIGINS.includes('*')) {
      return callback(null, true);
    }
    return callback(new Error('Not allowed by CORS'));
  },
  methods: ['GET', 'POST'],
  allowedHeaders: ['Content-Type', 'Authorization']
}));

// Health check
app.get('/health', (req, res) => {
  res.json({ status: 'ok', timestamp: new Date().toISOString() });
});

// Submit form
app.post('/submit', (req, res) => {
  try {
    const { email, form_name = 'default', source = null } = req.body;

    if (!email) {
      return res.status(400).json({ error: 'Email is required' });
    }

    // Basic email validation
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    if (!emailRegex.test(email)) {
      return res.status(400).json({ error: 'Invalid email format' });
    }

    const ip = req.headers['x-forwarded-for'] || req.socket.remoteAddress;
    const userAgent = req.headers['user-agent'] || null;

    const stmt = db.prepare(`
      INSERT INTO submissions (form_name, email, source, ip, user_agent)
      VALUES (?, ?, ?, ?, ?)
    `);

    const result = stmt.run(form_name, email.toLowerCase().trim(), source, ip, userAgent);

    res.json({
      success: true,
      id: result.lastInsertRowid,
      message: 'Submission received'
    });
  } catch (error) {
    console.error('Submit error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// Auth middleware for protected routes
const requireAuth = (req, res, next) => {
  if (!API_KEY) return next(); // No auth if no API_KEY set

  const authHeader = req.headers.authorization;
  if (!authHeader || authHeader !== `Bearer ${API_KEY}`) {
    return res.status(401).json({ error: 'Unauthorized' });
  }
  next();
};

// List submissions (protected)
app.get('/emails', requireAuth, (req, res) => {
  try {
    const { form_name, limit = 100, offset = 0 } = req.query;

    let query = 'SELECT * FROM submissions';
    const params = [];

    if (form_name) {
      query += ' WHERE form_name = ?';
      params.push(form_name);
    }

    query += ' ORDER BY created_at DESC LIMIT ? OFFSET ?';
    params.push(parseInt(limit), parseInt(offset));

    const submissions = db.prepare(query).all(...params);
    const countQuery = form_name
      ? db.prepare('SELECT COUNT(*) as count FROM submissions WHERE form_name = ?').get(form_name)
      : db.prepare('SELECT COUNT(*) as count FROM submissions').get();

    res.json({
      submissions,
      total: countQuery.count,
      limit: parseInt(limit),
      offset: parseInt(offset)
    });
  } catch (error) {
    console.error('List error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// Export as CSV (protected)
app.get('/export', requireAuth, (req, res) => {
  try {
    const { form_name } = req.query;

    let query = 'SELECT email, form_name, source, created_at FROM submissions';
    const params = [];

    if (form_name) {
      query += ' WHERE form_name = ?';
      params.push(form_name);
    }

    query += ' ORDER BY created_at DESC';

    const submissions = db.prepare(query).all(...params);

    const csv = [
      'email,form_name,source,created_at',
      ...submissions.map(s => `${s.email},${s.form_name},${s.source || ''},${s.created_at}`)
    ].join('\n');

    res.setHeader('Content-Type', 'text/csv');
    res.setHeader('Content-Disposition', `attachment; filename=submissions-${Date.now()}.csv`);
    res.send(csv);
  } catch (error) {
    console.error('Export error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// Stats (protected)
app.get('/stats', requireAuth, (req, res) => {
  try {
    const stats = db.prepare(`
      SELECT
        form_name,
        COUNT(*) as count,
        MIN(created_at) as first_submission,
        MAX(created_at) as last_submission
      FROM submissions
      GROUP BY form_name
      ORDER BY count DESC
    `).all();

    const total = db.prepare('SELECT COUNT(*) as count FROM submissions').get();

    res.json({
      total: total.count,
      by_form: stats
    });
  } catch (error) {
    console.error('Stats error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// Ensure data directory exists
const fs = require('fs');
const dataDir = path.dirname(dbPath);
if (!fs.existsSync(dataDir)) {
  fs.mkdirSync(dataDir, { recursive: true });
}

app.listen(PORT, () => {
  console.log(`Form capture service running on port ${PORT}`);
  console.log(`Allowed origins: ${ALLOWED_ORIGINS.join(', ')}`);
  console.log(`API key protection: ${API_KEY ? 'enabled' : 'disabled'}`);
});