const http = require('http');
const fs = require('fs');
const path = require('path');
const url = require('url');

const DATA_DIR = process.env.DATA_DIR || './data';
const PORT = process.env.PORT || 3001;

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

const server = http.createServer((req, res) => {
    // CORS headers
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
    res.setHeader('Access-Control-Allow-Headers', 'Content-Type');

    if (req.method === 'OPTIONS') {
        res.writeHead(204);
        res.end();
        return;
    }

    const parsedUrl = url.parse(req.url, true);
    const pathname = parsedUrl.pathname;
    
    // Path format: /kv/:key?token=...
    const match = pathname.match(/^\/kv\/([a-zA-Z0-9_-]+)$/);
    
    if (!match) {
        res.writeHead(404, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ error: 'Invalid path' }));
        return;
    }

    const key = match[1];
    const token = parsedUrl.query.token;

    if (!token) {
        res.writeHead(401, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ error: 'Token required' }));
        return;
    }

    // Simple file-based storage: data/{token}_{key}.json
    // Using token in filename ensures isolation between users
    const safeToken = token.replace(/[^a-zA-Z0-9]/g, '');
    const filePath = path.join(DATA_DIR, `${safeToken}_${key}.json`);

    if (req.method === 'GET') {
        if (fs.existsSync(filePath)) {
            const data = fs.readFileSync(filePath);
            res.writeHead(200, { 'Content-Type': 'application/json' });
            res.end(data);
        } else {
            res.writeHead(200, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify(null)); // Key not found returns null
        }
    } else if (req.method === 'POST') {
        let body = '';
        req.on('data', chunk => body += chunk.toString());
        req.on('end', () => {
            try {
                // Validate JSON
                JSON.parse(body);
                fs.writeFileSync(filePath, body);
                res.writeHead(200, { 'Content-Type': 'application/json' });
                res.end(JSON.stringify({ success: true }));
            } catch (e) {
                res.writeHead(400, { 'Content-Type': 'application/json' });
                res.end(JSON.stringify({ error: 'Invalid JSON' }));
            }
        });
    } else {
        res.writeHead(405);
        res.end();
    }
});

server.listen(PORT, () => {
    console.log(`Sync Server running on port ${PORT}`);
    console.log(`Data directory: ${DATA_DIR}`);
});