'use strict';
var http=require('http');
var url=require('url');
var path=require('path');
var fs=require('fs');
var fss=require('mz/fs');
var root=path.resolve(process.argv[2]||'.');
var server=http.createServer((req,res)=>{
        console.log(req.method+':'+req.url);
        var pathname=url.parse(req.url).pathname;
        var filepath=path.join(root,pathname);
        fs.stat(filepath,(err,stats)=>{
            if(!err&&stats.isFile()){
               console.log('200'+req.url);
               res.writeHead(200);
               fs.createReadStream(filepath).pipe(res);
            }else{
                console.log('404'+req.url);
                res.writeHead(404);
                res.end("404 Not Found");    
            } 
        });
    });
module.exports=async ()=>{
    let expression=await fss.readFile('./data.txt','utf-8');
    let fn=new Function("return "+expression);
    let r=fn();
    console.log(`Calculate:${expression}=${r}`);
    return r;
}
server.listen(3000);