simple http server

var http = require('http');
var fs = require('fs');

var checkFile = function(file){
	return new Promise(function(resolve, reject){
		fs.exists(file, function(exists){
			resolve(exists);
		});
	});
}



function getFileNameFromUrl(url){
	var tmpUrl = url.trim().substr(1);
	//strip some dots info for secure
	tmpUrl = tmpUrl.replace(/\.\.\//g, '');
	if (tmpUrl.indexOf('?')>=0)
		return tmpUrl.substr(0, tmpUrl.indexOf('?')); 
	else
		return tmpUrl;
}

function getFileExtensionFromName(filename){
	return filename.split('.').pop();
}
var mimeTypeMap = {
	'css': 'text/css',
	'js': 'application/javascript',
	'html': 'text/html'
};
var server = http.createServer(function(req, res){
	var url = req.url;
	var fileName = getFileNameFromUrl(url);
	var filePath = './static/'+fileName;
	checkFile(filePath).
	then(function(check){
		if (!check)
		{
			var body = 'File not found';
			res.writeHead(404,
				{
					'Content-length':body.length,
					'Content-type': 'text/plain'
				}
			);
			return void res.end(body);
		}
		var extension = getFileExtensionFromName(fileName);
		if (mimeTypeMap[extension])
		{
			res.writeHead(200,
				{
					'Content-type': mimeTypeMap[extension]
				}
			);
		}
		var fileStream = fs.createReadStream(filePath);
		fileStream.pipe(res);
	})
});

server.listen(5300);