const http = require('node:http');
const fs = require('node:fs');
const path = require('node:path');
const crypto = require('node:crypto');

const PORT = process.env.PORT || 3000;
const DATA_DIR = path.join(__dirname, 'data');
const MAX_SIZE_BYTES = 10 * 1024 * 1024; // 10MB

if (!fs.existsSync(DATA_DIR)) fs.mkdirSync(DATA_DIR);

const sendJSON = (res, status, data) => {
    res.writeHead(status, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify(data));
};

const server = http.createServer((req, res) => {
    const { method, url } = req;

    // Serve Frontend
    if (method === 'GET' && (url === '/' || url.startsWith('/view'))) {
        res.writeHead(200, { 'Content-Type': 'text/html' });
        fs.createReadStream(path.join(__dirname, 'index.html')).pipe(res);
        return;
    }

    // CREATE Secret (Public POST)
    if (method === 'POST' && url === '/api/secret') {
        const contentLength = parseInt(req.headers['content-length'], 10);
        if (contentLength > MAX_SIZE_BYTES) {
            res.writeHead(413); return res.end('Too large');
        }

        const id = crypto.randomUUID(); // Unique and Random URL component
        const filePath = path.join(DATA_DIR, id);
        const writeStream = fs.createWriteStream(filePath);

        req.pipe(writeStream);
        req.on('end', () => sendJSON(res, 201, { id }));
        writeStream.on('error', () => { res.writeHead(500); res.end(); });
        return;
    }

    // READ & BURN Secret
    if (method === 'GET' && url.startsWith('/api/secret/')) {
        const id = url.split('/').pop();
        if (!/^[a-z0-9-]+$/i.test(id)) { res.writeHead(400); return res.end(); }

        const filePath = path.join(DATA_DIR, id);
        if (!fs.existsSync(filePath)) {
            res.writeHead(404); return res.end('Burned or Not Found');
        }

        const readStream = fs.createReadStream(filePath);
        res.writeHead(200, { 'Content-Type': 'application/octet-stream' });
        readStream.pipe(res);

        // Delete immediately after stream ends
        readStream.on('end', () => {
            fs.unlink(filePath, (err) => { if (err) console.error("Burn failed", err); });
        });
        return;
    }

    res.writeHead(404); res.end();
});

server.listen(PORT, () => console.log(`Public Burn Server: http://localhost:${PORT}`));