const express = require('express');
const cors = require('cors');
const axios = require('axios');
const cheerio = require('cheerio');

const app = express();
const PORT = process.env.PORT || 3000;

// Middleware
app.use(cors());
app.use(express.json());

// Proxy endpoint
app.get('/proxy', async (req, res) => {
    try {
        const targetUrl = req.query.url;
        if (!targetUrl) {
            return res.status(400).send('URL parameter is required');
        }

        // Validate URL
        try {
            new URL(targetUrl);
        } catch (e) {
            return res.status(400).send('Invalid URL');
        }

        // Fetch the target page
        const response = await axios.get(targetUrl, {
            headers: {
                'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36'
            }
        });

        // Process the HTML to rewrite links
        const $ = cheerio.load(response.data);
        
        // Rewrite all links to go through our proxy
        $('a[href]').each((i, el) => {
            const href = $(el).attr('href');
            try {
                const url = new URL(href, targetUrl);
                $(el).attr('href', `/proxy?url=${encodeURIComponent(url.href)}`);
            } catch (e) {
                // Skip invalid URLs
            }
        });

        // Rewrite all form actions to go through our proxy
        $('form[action]').each((i, el) => {
            const action = $(el).attr('action');
            try {
                const url = new URL(action, targetUrl);
                $(el).attr('action', `/proxy?url=${encodeURIComponent(url.href)}`);
            } catch (e) {
                // Skip invalid URLs
            }
        });

        // Send the modified content
        res.set('Content-Type', response.headers['content-type']);
        res.send($.html());

    } catch (error) {
        console.error('Proxy error:', error);
        res.status(500).send('Error fetching the requested URL');
    }
});

// Start server
app.listen(PORT, () => {
    console.log(`Proxy server running on port ${PORT}`);
});