server.js

require('dotenv').config();
const express = require('express');
const { createProxyMiddleware } = require('http-proxy-middleware');
const cors = require('cors');

const app = express();
const PORT = process.env.PORT || 8501;
const STREAMLIT_URL = process.env.STREAMLIT_URL || 'http://localhost:8501';

// CORS configuration from environment variables
const corsOptions = {
  origin: process.env.CORS_ORIGIN || '*',
  credentials: process.env.CORS_CREDENTIALS === 'true',
  methods: (process.env.CORS_METHODS || 'GET,POST,PUT,DELETE,OPTIONS,PATCH').split(','),
  allowedHeaders: (process.env.CORS_ALLOWED_HEADERS || 'Content-Type,Authorization,X-Requested-With,Accept,Origin').split(','),
  optionsSuccessStatus: 200
};

app.use(cors(corsOptions));

// Additional CORS headers
app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', '*');
  res.header('Access-Control-Allow-Headers', '*');
  res.header('X-Frame-Options', 'ALLOWALL');
  
  if (req.method === 'OPTIONS') {
    return res.status(200).end();
  }
  
  next();
});

// Replace this URL with your actual Streamlit app URL


// Proxy configuration
const proxyOptions = {
  target: STREAMLIT_URL,
  changeOrigin: true,
  secure: true,
  ws: true, // WebSocket support
  logLevel: 'info',
  onProxyReq: (proxyReq, req, res) => {
    console.log(`Proxying: ${req.method} ${req.url}`);
    // Clean up headers
    proxyReq.removeHeader('x-forwarded-host');
    proxyReq.setHeader('host', STREAMLIT_URL.replace('https://', ''));
  },
  onProxyRes: (proxyRes, req, res) => {
    console.log(`Response: ${proxyRes.statusCode}`);
    // Remove restrictive headers
    delete proxyRes.headers['x-frame-options'];
    delete proxyRes.headers['content-security-policy'];
    delete proxyRes.headers['x-content-type-options'];
    
    // Add permissive headers
    proxyRes.headers['x-frame-options'] = 'ALLOWALL';
    proxyRes.headers['access-control-allow-origin'] = '*';
  },
  onError: (err, req, res) => {
    console.error('Proxy error:', err);
    res.status(500).send('Proxy error: ' + err.message);
  }
};

// Apply proxy to all routes
app.use('/', createProxyMiddleware(proxyOptions));

// Health check endpoint
app.get('/health', (req, res) => {
  res.json({ status: 'OK', target: STREAMLIT_URL });
});

app.listen(PORT, () => {
  console.log(`🚀 Proxy server running on port ${PORT}`);
  console.log(`🎯 Proxying to: ${STREAMLIT_URL}`);
  console.log(`🌐 CORS enabled for ALL origins`);
});