server.js

const express = require("express");
const bodyParser = require("body-parser");
var session = require("express-session");
var multer = require("multer");
const path = require("path");
const fs = require("fs");
var rn = require("random-number");
var sleep = require("system-sleep");
var md5 = require("md5");
// var redis = require('redis');
// var client = redis.createClient();
var app = express();
var sha256File = require("sha256-file");
const low = require("lowdb");
const FileSync = require("lowdb/adapters/FileSync");
const adapter = new FileSync("db.json");
const db = low(adapter);
//Constant Definitions
const PORT = process.env.PORT || 3000;
const NODE_ENV = process.env.NODE_ENV || "development";
app.set("port", PORT);
app.set("env", NODE_ENV);
var upload = multer({ dest: "uploads/" });
var urlencodedParser = bodyParser.urlencoded({ extended: false });
var cookieParser = require('cookie-parser')
app.use(cookieParser());
app.use(express.static(__dirname));

// if(PORT==3000){
// //Establish Redis connection
// client.on('connect', function() {
//     console.log('Redis client connected');
// });
//
// client.on('error', function (err) {
//     console.log('Something went wrong ' + err);
// });
// }
//End point to register
app.post("/register", urlencodedParser, function(req, res) {
  pass = md5(req.param("password"));
  success = registerUser(
    req.param("first_name"),
    req.param("last_name"),
    req.param("email"),
    req.param("organization"),
    pass
  );
  console.log("Registered Succesfully");
  console.log(pass);
  if (success) {
    res.redirect("/login.html");
  } else {
    res.send("User already exists, please Login");
  }
});


//End point for Actual Login
app.post("/login", urlencodedParser, function(req, res) {
  pass = req.param("password");
  element = db
    .get("user")
    .find({ pass: md5(pass) })
    .value();
  console.log(element);
  if (element.email == req.param("email")) {
    res.cookie('user',req.param("email"), { maxAge: 900000, httpOnly: false })
    res.redirect("/profile.html");
    
    // client.set('email', req.param('email'), redis.print);
  }
});

//End point to upload the File
app.post("/upload", upload.single("file"), function(req, res, next) {
  var now = new Date();
  var pass = req.param("pass");
  var jsonDate = now.toJSON();
  var organization = "coding.Studio();";
  file = req.file;
  console.log(file);
  sha256File("./uploads/" + req.file.filename, function(error, sum) {
    if (error) return console.log(error);
    console.log(sum);
    storeDB(req.file.originalname, req.file.filename, sum);
    file_success = generateDB(
      req.file.originalname,
      req.file.filename,
      sum,
      organization,
      jsonDate,
      pass
    );
    
    file_no = rn(0000, 9999);
    fs.writeFileSync(file_no + ".json", file_success);
    res.sendFile(__dirname + "/" + file_no + ".json");
    sleep(500);
    fs.unlink(__dirname + "/" + file_no + ".json", function(err) {
      if (err) throw err;
      console.log("File deleted!");
    });
  });
});

//End point for fetching the file
app.post("/fetch", upload.single("file"), function(req, res, next) {
  file = req.file;
  password = md5(req.param("pass"))
  console.log(file.filename);
  let rawdata = fs.readFileSync(__dirname + "/uploads/" + file.filename)
  let data = JSON.parse(rawdata);
  console.log(data);
  new_file = data.new_name;
  orig_file = data.orig_name;
  new_file = findFile(new_file);
  console.log(new_file)
  if(password==data.pass){
      res.download(new_file,orig_file);
  }
  else{
    res.send("Invalid Password, Please try again!")
  }
});

//End point for File Verification
app.post("/verify", upload.single("file"), function(req, res, next) {
  file = req.file;
  sha256File("./uploads/" + req.file.filename, function(error, sum) {
    if (error) return console.log(error);
    console.log(sum);
    if (verifyFile(sum) == 1) {
      res.sendFile(__dirname + "/assets/img/notmodified.png");
      console.log("Not modified");
    } else {
      res.sendFile(__dirname + "/assets/img/modified.png");
      
    }
    fs.unlink(req.file.path, function(err) {
      if (err) throw err;
      // if no error, file has been deleted successfully
      console.log("File deleted!");
    });
    //if sum exists then return verified
  });
});

//Store the new and original name of the file in the DB along with the SUM
function storeDB(orig_name, new_name, sha_value) {
  db.get("key")
    .push({ orig: orig_name, new: new_name, sha: sha_value })
    .write();
  db.update("count", n => n + 1).write();
}

//Funcrion to register the user
function registerUser(first_name, last_name, email, org, password) {
  element = db
    .get("user")
    .find({ email: email })
    .value();
  if (!element) {
    db.get("user")
      .push({
        first_name: first_name,
        last_name: last_name,
        email: email,
        organization: org,
        pass: password
      })
      .write();
      console.log(first_name)
    return true;
  }
}



//Function to generate the certificate
function generateDB(orig, new_name, sum, org, date, pass) {
  hash = md5(pass);
  //generate a DB
  let key = {
    orig_name: orig,
    new_name: new_name,
    hash: sum,
    organization: org,
    Date: date,
    pass: hash
  };
  let data = JSON.stringify(key, null, 4);
  return data;
}
//Find element function for verifiction
function findFile(new_file) {
  result_url = __dirname + "/uploads/" + new_file;
  return result_url;
}
//Function to verify the file
function verifyFile(sha_value) {
  element = db
    .get("key")
    .find({ sha: sha_value })
    .value();
  console.log(element);
  if (element) {
    return true;
  }
}
//App listen on the constants defined
app.listen(PORT, () => {
  console.log(
    `Express Server started on Port ${app.get(
      "port"
    )} | Environment : ${app.get("env")}`
  );
});