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var express = require('express');
var app = express();
var fs = require("fs");
var bodyParser = require('body-parser');
// Create application/x-www-form-urlencoded parser
var urlencodedParser = bodyParser.urlencoded({ extended: false })
var authenticatedUser = null;
app.use(express.static('public'));
/**** This part to handle default request url= localhost:8081 ******/
app.get('/', function (req, res) {
  res.sendFile( __dirname + "/" + "login.html" );
})
/**** This is an example on how to include local libraries, the libraries are defined in the html using
script src="http://127.0.0.1:8081/test.js" so you need to create ar response for this get request ******/
app.get('/test.js', function (req, res) {
  res.sendFile( __dirname + "/" + "test.js" );
})
/**** This is an example on login request where you need to verify the username and password for authentication
normally login requests are POST method to prevent the password from showing on the url  ****/
app.post('/login', urlencodedParser, function (req, res) {
// Get the values of the input text named username & password
  username = req.body.username;
  password = req.body.password;
  // console.log(username);
  // console.log(password);
  // Read JSON file containing the users to verify that the user is already registered and have access
  fs.readFile( __dirname + "/" + "users.json", 'utf8', function (err, data) {
    // Note that err here is for handling any error occuring in opening the file
    data = JSON.parse( data );
    var flag = 0;
    for (var user in data) {
      if(username == data[user].name){flag = 1; authenticatedUser = user; break;}
      else{flag = 0;  }
    }
    if(flag == 1){
      // Handling verified users by opening their html from the json file.
      fs.readFile( __dirname + "/" + "tables.json", 'utf8', function (err, tables_data) {
        tables_data = JSON.parse(tables_data);
        //console.log(tables_data[user].html);
        // necessary in case multiple clicks are commited
        res.setHeader('X-XSS-Protection', 0);
        res.writeHead(200, {'Content-Type': 'text/html'});
        // load the html of the user
        res.end((tables_data[user].html));
      });

    }
    // Handle invalid login by redirecting the user to the login page once again
    else{res.sendFile( __dirname + "/" + "login.html" );}
  });
 })
 /******* Handle any update done by the user ********/
 app.post('/save', urlencodedParser, function (req, res) {
   // get the dummy input text field containing the entire html string
   body = req.body.dummy;
   // console.log(body);
   // open the JSON file to update with the new update user page after modifications
   fs.readFile( __dirname + "/" + "tables.json", 'utf8', function (err, data) {
     data = JSON.parse( data );
     data[authenticatedUser].html = "<html>" + body + "</html>";
     // Write the changes to the JSON file
     fs.writeFile(__dirname + "/" + "tables.json",JSON.stringify(data), function (err) {
        if (err) return console.log(err);
        //console.log(JSON.stringify(data));
      });
    console.log(authenticatedUser);
    res.setHeader('X-XSS-Protection', 0);
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.end(data[authenticatedUser].html);
  });

  })

var server = app.listen(8081, function () {
var host = server.address().address
var port = server.address().port
console.log("Example app listening at http://%s:%s", host, port) })