Complete code for front-end and back-end.

.gitignore

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+Assignment1/node_modules

Assignment1/README.md

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+# This is a code base for a Note-making app created using express for back-end, react for front-end and mongodb for data storage.
+
+# Back-end
+
+1. The code is organised into two directories viz backend and frontend.
+
+2. /backend contains the entry point file viz main.js. 
+
+3. /backend/routeHandler contains the handler functions for register, login, add notes, delete notes and view notes end points.
+
+4. /backend/middleware contains middleware for verifying user identity before accessing /view, /addNotes and /delete end points.
+
+5. User authentication and authorisation is achieved using JSON web tokens. Feature for refreshing tokens is still to be added.
+
+6. MongoDB is used as a database for storing user information. 
+
+# Front-end
+
+1. /frontend/src/App.js is entry point for the app using various react components defined in frontend/src/Components directory.
+
+2. /frontend/src/Components contains the various react components.
+
+# Access the app on https://immense-inlet-55002.herokuapp.com/
+

Assignment1/backend/config.json

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+{
+    "secret" : "Mysecret" 
+}

Assignment1/backend/main.js

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+const express = require('express');
+const app = express();
+const cors = require('cors');
+const verify = require('./middleware/verify');
+const register = require('./routeHandler/register');
+const view = require('./routeHandler/view')
+const add = require('./routeHandler/addNote')
+const login = require('./routeHandler/login');
+const deleteNote = require('./routeHandler/delete');
+const path = require('path');
+app.use(express.json());
+app.use(cors());
+
+// if(process.env.NODE_ENV === 'production'){
+    // app.use(express.static('../frontend/build'));
+    // app.post('*',(req,res)=>{
+    //     res.sendFile(path.resolve(dirname,'build','index.html'));
+    // })
+    app.use(express.static(path.join(__dirname, '../frontend/build')));
+//     app.use('/', (req, res) => {
+//     res.sendFile(path.join(__dirname, '../frontend/build'));
+// })
+// }
+
+
+const port = process.env.PORT || 5000;
+
+app.post('/login',login)
+app.post("/register",register);
+app.use(verify);
+app.post("/view",view.view);
+app.post('/addNotes',add);
+app.post('/delete',deleteNote);
+// app.post("/login",auth.login);
+
+app.listen(port,()=>console.log("Server started on",port));
+
+

Assignment1/backend/middleware/verify.js

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+const jwt = require('jsonwebtoken');
+const config = require('../config.json');
+var MongoClient = require('mongodb').MongoClient;
+var url = "mongodb+srv://Arpitkr:Arpit299792458@cluster0.z2ut1.mongodb.net/myFirstDatabase?retryWrites=true&w=majority";
+let db = null;
+MongoClient.connect(url,function(err,client){
+    if(err) throw err
+    db = client
+})
+const checkEmail = require('../routeHandler/view').checkEmail;
+
+async function verify(req,res,next){
+    let dbo = db.db('User');
+    let result = await checkEmail(req.body.email,dbo,res);
+    if(!result.check){
+        return;
+    }
+    if (!req.headers['authorization']){
+        return res.status(401).json({"auth":false,"msg": "Status unauthorised"});
+    }
+    let token = req.headers['authorization'].split(' ')[1];
+    if (!token){
+        return res.status(401).json({"auth":false,"msg": "Status unauthorised"});
+    }
+    try{
+        let payload = jwt.verify(token,config.secret);
+    }catch(err){
+        return res.status(401).json({"auth":false,"msg": "Status unauthorised."});
+    }
+    next();
+}
+
+module.exports = verify;

Assignment1/backend/routeHandler/addNote.js

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+var MongoClient = require('mongodb').MongoClient;
+var url = "mongodb+srv://Arpitkr:Arpit299792458@cluster0.z2ut1.mongodb.net/myFirstDatabase?retryWrites=true&w=majority";
+let db = null;
+MongoClient.connect(url,function(err,client){
+    if(err) throw err
+    db = client
+})
+
+async function addNotes(req,res){
+    let dbo = db.db("User");
+    let result = await dbo.collection("Customers").find({email : req.body.email}).toArray();
+
+    if(result[0].notes){
+        result[0].notes.unshift(req.body.data);
+        await dbo.collection("Customers").updateOne({email : req.body.email},{$set : {notes : result[0].notes}});
+        let index = parseInt(req.body.index);
+        if(!(index===-1)){
+            result[0].notes.splice(index+1,1);
+            await dbo.collection("Customers").updateOne({email : req.body.email},{$set : {notes : result[0].notes}});
+        }
+    }
+    else{
+        await dbo.collection("Customers").updateOne({email : req.body.email},{$set : {notes : new Array(req.body.data)}});
+    }
+    return res.status(200).json({"msg" : "Notes added successfully","data":result[0].notes});
+}
+
+module.exports = addNotes;

Assignment1/backend/routeHandler/delete.js

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+var MongoClient = require('mongodb').MongoClient;
+// var url = "mongodb://localhost:27017/";
+var url = "mongodb+srv://Arpitkr:Arpit299792458@cluster0.z2ut1.mongodb.net/myFirstDatabase?retryWrites=true&w=majority";
+let db = null;
+MongoClient.connect(url,function(err,client){
+    if(err) throw err
+    db = client
+})
+
+async function deleteNote(req,res){
+    let dbo = db.db("User");
+    let result = await dbo.collection("Customers").find({email: req.body.email}).toArray();
+    let index = parseInt(req.body.index);
+    if(result[0].notes[index]){
+        result[0].notes.splice(index,1);
+        await dbo.collection("Customers").updateOne({email : req.body.email},{$set : {notes : result[0].notes}});
+        res.status(200).json({"data":result[0].notes,"msg":"Deleted successfully"});
+    }
+    return res.status(400);
+}
+
+module.exports = deleteNote;

Assignment1/backend/routeHandler/login.js

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+const bcrypt = require('bcryptjs');
+const config = require('../config.json')
+const checkEmail = require('./view').checkEmail;
+
+var MongoClient = require('mongodb').MongoClient;
+const jwt = require('jsonwebtoken');
+var url = "mongodb+srv://Arpitkr:Arpit299792458@cluster0.z2ut1.mongodb.net/myFirstDatabase?retryWrites=true&w=majority";
+let db = null;
+MongoClient.connect(url,function(err,client){
+    if(err) throw err
+    db = client
+})
+
+async function login(req,res){
+    let dbo = db.db("User");
+    let result = await checkEmail(req.body.email,dbo,res);
+    if(result.check){
+        if(!bcrypt.compareSync(req.body.password,result.result[0].password)){
+            return res.status(401).json({"msg":"Invalid password"});
+        }
+        let token = jwt.sign({email: req.body.email},config.secret,{expiresIn : 86400});
+        return res.status(200).json({"auth" :true,"msg":"User logged in successfully","token":token});
+    }
+}
+
+module.exports = login;

Assignment1/backend/routeHandler/register.js

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+const bcrypt = require('bcryptjs');
+const config = require('../config.json')
+
+var MongoClient = require('mongodb').MongoClient;
+const jwt = require('jsonwebtoken');
+var url = "mongodb+srv://Arpitkr:Arpit299792458@cluster0.z2ut1.mongodb.net/myFirstDatabase?retryWrites=true&w=majority";
+let db = null;
+MongoClient.connect(url,function(err,client){
+    if(err) throw err
+    db = client
+})
+
+
+async function register(req,res){
+    let dbo = db.db("User");
+    let query = {email : req.body.email};
+    let result = await dbo.collection("Customers").find(query).toArray();
+    res.set('Access-Control-Allow-Origin', '*');
+    if(result.length>0){
+        return res.status(401).json({"msg": "Email already in use"});
+    }
+    let hashedPassword = bcrypt.hashSync(req.body.password,8);
+    req.body.password = hashedPassword;
+    let data = {email : req.body.email, password : req.body.password}
+    await dbo.collection("Customers").insertOne(data);
+    let token = jwt.sign({email: req.body.email},config.secret,{expiresIn : 86400});
+    return res.status(200).json({"auth" :true,"msg":"User added successfully",token:token});
+}
+
+module.exports = register;

Assignment1/backend/routeHandler/view.js

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+var MongoClient = require('mongodb').MongoClient;
+var url = "mongodb+srv://Arpitkr:Arpit299792458@cluster0.z2ut1.mongodb.net/myFirstDatabase?retryWrites=true&w=majority";
+let db = null;
+MongoClient.connect(url,function(err,client){
+    if(err) throw err
+    db = client
+})
+
+async function checkEmail(email,dbo,res){
+    let result = await dbo.collection("Customers").find({email : email}).toArray();
+    if(result.length == 0){
+        res.status(400).json({"msg" : `${email} is not registered.`});
+        return {check : false, result : result};
+    }
+    return {check : true, result : result};
+}
+
+
+//This end point receives a post request containing the email and noteID of user and returns the corresponding note in json format 
+async function view(req,res){
+    let dbo = db.db("User");
+    let result = await dbo.collection("Customers").find({email : req.body.email}).toArray();
+
+    res.status(200).json({"data" : result[0].notes});
+}
+
+module.exports = {view,checkEmail};

Assignment1/frontend/.gitignore

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+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# production
+/build
+
+# misc
+.DS_Store
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*

Assignment1/frontend/README.md

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+# Getting Started with Create React App
+
+This project was bootstrapped with [Create React App](https://github.com/facebook/create-react-app).
+
+## Available Scripts
+
+In the project directory, you can run:
+
+### `npm start`
+
+Runs the app in the development mode.\
+Open [http://localhost:3000](http://localhost:3000) to view it in the browser.
+
+The page will reload if you make edits.\
+You will also see any lint errors in the console.
+
+### `npm test`
+
+Launches the test runner in the interactive watch mode.\
+See the section about [running tests](https://facebook.github.io/create-react-app/docs/running-tests) for more information.
+
+### `npm run build`
+
+Builds the app for production to the `build` folder.\
+It correctly bundles React in production mode and optimizes the build for the best performance.
+
+The build is minified and the filenames include the hashes.\
+Your app is ready to be deployed!
+
+See the section about [deployment](https://facebook.github.io/create-react-app/docs/deployment) for more information.
+
+### `npm run eject`
+
+**Note: this is a one-way operation. Once you `eject`, you can’t go back!**
+
+If you aren’t satisfied with the build tool and configuration choices, you can `eject` at any time. This command will remove the single build dependency from your project.
+
+Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except `eject` will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
+
+You don’t have to ever use `eject`. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.
+
+## Learn More
+
+You can learn more in the [Create React App documentation](https://facebook.github.io/create-react-app/docs/getting-started).
+
+To learn React, check out the [React documentation](https://reactjs.org/).
+
+### Code Splitting
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/code-splitting](https://facebook.github.io/create-react-app/docs/code-splitting)
+
+### Analyzing the Bundle Size
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size](https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size)
+
+### Making a Progressive Web App
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app](https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app)
+
+### Advanced Configuration
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/advanced-configuration](https://facebook.github.io/create-react-app/docs/advanced-configuration)
+
+### Deployment
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/deployment](https://facebook.github.io/create-react-app/docs/deployment)
+
+### `npm run build` fails to minify
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify](https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify)