server.js

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

const PORT = 3000;
const HOSTNAME = 'localhost';

// MIME types for different file extensions
// Ye browser ko batata hai ki file ka type kya hai
const mimeTypes = {
    '.html': 'text/html',
    '.css': 'text/css',
    '.js': 'text/javascript',
    '.json': 'application/json',
    '.png': 'image/png',
    '.jpg': 'image/jpeg',
    '.gif': 'image/gif',
    '.svg': 'image/svg+xml'
};

// HTTP Server banao using built-in http module
const server = http.createServer((req, res) => {
    console.log(`Request: ${req.method} ${req.url}`);

    // API endpoint for signal data
    if (req.url === '/api/signal-data' && req.method === 'GET') {
        handleApiRequest(req, res);
        return;
    }

    // Static file serving
    handleStaticFiles(req, res);
});

// Function to handle API requests (JSON data ko send karne ke liye)
function handleApiRequest(req, res) {
    const dataPath = path.join(__dirname, 'public', 'data', 'rsrq_sample_100.json');
    
    // File ko read karo
    fs.readFile(dataPath, 'utf8', (err, data) => {
        if (err) {
            console.error('Error reading JSON file:', err);
            res.writeHead(500, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify({ error: 'Failed to load signal data' }));
            return;
        }

        // JSON response send karo
        res.writeHead(200, { 
            'Content-Type': 'application/json',
            'Access-Control-Allow-Origin': '*' 
        });
        res.end(data);
        console.log('✅ Sent signal data');
    });
}

// Function to handle static files (HTML, CSS, JS files)
function handleStaticFiles(req, res) {
    // Root URL ko index.html pe redirect karo
    let filePath = req.url === '/' ? '/index.html' : req.url;
    filePath = path.join(__dirname, 'public', filePath);

    // File extension nikalo to determine MIME type
    const extname = path.extname(filePath).toLowerCase();
    const contentType = mimeTypes[extname] || 'application/octet-stream';

    // Check if file exists
    fs.access(filePath, fs.constants.F_OK, (err) => {
        if (err) {
            // File not found - 404 response
            console.log('File not found:', filePath);
            res.writeHead(404, { 'Content-Type': 'text/html' });
            res.end('<h1>404 - File Not Found</h1>');
            return;
        }

        // File exists - read and send it
        fs.readFile(filePath, (err, content) => {
            if (err) {
                console.error('Error reading file:', err);
                res.writeHead(500, { 'Content-Type': 'text/html' });
                res.end('<h1>500 - Internal Server Error</h1>');
                return;
            }

            // Success - send file with correct content type
            res.writeHead(200, { 'Content-Type': contentType });
            res.end(content);
            console.log(`✅ Served: ${req.url}`);
        });
    });
}

// Server start karo
server.listen(PORT, HOSTNAME, () => {
    console.log(`🚀 Server running at http://${HOSTNAME}:${PORT}/`);
});

// Graceful shutdown
process.on('SIGINT', () => {
    console.log('\n\n👋 Server shutting down...');
    server.close(() => {
        console.log('✅ Server closed successfully');
        process.exit(0);
    });
});