const express = require('express');
const cors = require('cors');
const initSqlJs = require('sql.js');
const fs = require('fs');
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(',');

// Database setup
const dataDir = process.env.DATA_DIR || path.join(__dirname, 'data');
const dbPath = path.join(dataDir, 'forms.db');
let db;

// Ensure data directory exists
if (!fs.existsSync(dataDir)) {
  fs.mkdirSync(dataDir, { recursive: true });
}

// Save database to file periodically
function saveDb() {
  if (db) {
    const data = db.export();
    fs.writeFileSync(dbPath, Buffer.from(data));
  }
}

// Initialize database
async function initDb() {
  const SQL = await initSqlJs();

  // Load existing database or create new one
  if (fs.existsSync(dbPath)) {
    const fileBuffer = fs.readFileSync(dbPath);
    db = new SQL.Database(fileBuffer);
  } else {
    db = new SQL.Database();
  }

  // Create tables
  db.run(`
    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
    )
  `);
  db.run(`CREATE INDEX IF NOT EXISTS idx_form_name ON submissions(form_name)`);
  db.run(`CREATE INDEX IF NOT EXISTS idx_email ON submissions(email)`);

  saveDb();

  // Auto-save every 30 seconds
  setInterval(saveDb, 30000);
}

// Middleware
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(cors({
  origin: (origin, callback) => {
    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' });
    }

    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;

    db.run(
      `INSERT INTO submissions (form_name, email, source, ip, user_agent, created_at) VALUES (?, ?, ?, ?, ?, datetime('now'))`,
      [form_name, email.toLowerCase().trim(), source, ip, userAgent]
    );

    saveDb();

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

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

// List submissions
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 stmt = db.prepare(query);
    stmt.bind(params);

    const submissions = [];
    while (stmt.step()) {
      submissions.push(stmt.getAsObject());
    }
    stmt.free();

    const countStmt = form_name
      ? db.prepare('SELECT COUNT(*) as count FROM submissions WHERE form_name = ?')
      : db.prepare('SELECT COUNT(*) as count FROM submissions');
    if (form_name) countStmt.bind([form_name]);
    countStmt.step();
    const total = countStmt.getAsObject().count;
    countStmt.free();

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

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

    let query = 'SELECT email, form_name, source, created_at FROM submissions';
    if (form_name) query += ' WHERE form_name = ?';
    query += ' ORDER BY created_at DESC';

    const stmt = db.prepare(query);
    if (form_name) stmt.bind([form_name]);

    const rows = [];
    while (stmt.step()) {
      rows.push(stmt.getAsObject());
    }
    stmt.free();

    const csv = [
      'email,form_name,source,created_at',
      ...rows.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
app.get('/stats', requireAuth, (req, res) => {
  try {
    const stmt = 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
    `);

    const stats = [];
    while (stmt.step()) {
      stats.push(stmt.getAsObject());
    }
    stmt.free();

    const totalStmt = db.prepare('SELECT COUNT(*) as count FROM submissions');
    totalStmt.step();
    const total = totalStmt.getAsObject().count;
    totalStmt.free();

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

// Start server after DB init
initDb().then(() => {
  app.listen(PORT, () => {
    console.log(`Form capture running on port ${PORT}`);
    console.log(`Allowed origins: ${ALLOWED_ORIGINS.join(', ')}`);
    console.log(`API key: ${API_KEY ? 'enabled' : 'disabled'}`);
  });
}).catch(err => {
  console.error('Failed to init database:', err);
  process.exit(1);
});