server.js

const express = require('express');
const app = express();
const mysql = require('mysql2');
const session = require('express-session');
const bcrypt = require('bcrypt');
const bodyParser = require('body-parser');
const crypto = require('crypto');
const Web3 = require('web3');
const BigNumber = require('bignumber.js');
const fs = require('fs');
// const io = require('socket.io')(app);

// Secret ID for session
const secret_id = 92;

// Salt for hashing
const saltRounds = 10;

// IP and port
const IP = '127.0.0.1';
const port = process.env.PORT || 8080;

// View engine
// app.set('views', path.join(__dirname, 'views'));
// app.set('view engine', 'ejs');

// Body-parser Middleware
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
	extended: true
}));

// Express session Middleware
// app.use(session({
//     secret: secret_id,
//     saveUninitialized: true,
//     resave: true
// }));

// MySQL Connection
const connection = mysql.createConnection({
	host: IP,
	user: "root",
	password: "root",
	database: 'authentifi',
	port: 3306
});

connection.connect(function (err) {
	if (!err) {
		console.log('Connected to MySql!\n');
	} else {
		console.log('Not connected to MySql.\n' + err);
	}
});

// Web3 connection
const web3 = new Web3("http://127.0.0.1:8545");
console.log(`Talking with a geth server ${web3.version.api} \n`);

const abiArray = [
	{
		"constant": false,
		"inputs": [
			{
				"name": "_code",
				"type": "string"
			},
			{
				"name": "_hashedEmailRetailer",
				"type": "string"
			}
		],
		"name": "addRetailerToCode",
		"outputs": [
			{
				"name": "",
				"type": "uint256"
			}
		],
		"payable": true,
		"stateMutability": "payable",
		"type": "function"
	},
	{
		"constant": false,
		"inputs": [
			{
				"name": "_code",
				"type": "string"
			},
			{
				"name": "_oldCustomer",
				"type": "string"
			},
			{
				"name": "_newCustomer",
				"type": "string"
			}
		],
		"name": "changeOwner",
		"outputs": [
			{
				"name": "",
				"type": "bool"
			}
		],
		"payable": true,
		"stateMutability": "payable",
		"type": "function"
	},
	{
		"constant": false,
		"inputs": [
			{
				"name": "_code",
				"type": "string"
			},
			{
				"name": "_brand",
				"type": "string"
			},
			{
				"name": "_model",
				"type": "string"
			},
			{
				"name": "_status",
				"type": "uint256"
			},
			{
				"name": "_description",
				"type": "string"
			},
			{
				"name": "_manufactuerName",
				"type": "string"
			},
			{
				"name": "_manufactuerLocation",
				"type": "string"
			},
			{
				"name": "_manufactuerTimestamp",
				"type": "string"
			}
		],
		"name": "createCode",
		"outputs": [
			{
				"name": "",
				"type": "uint256"
			}
		],
		"payable": true,
		"stateMutability": "payable",
		"type": "function"
	},
	{
		"constant": false,
		"inputs": [
			{
				"name": "_hashedEmail",
				"type": "string"
			},
			{
				"name": "_name",
				"type": "string"
			},
			{
				"name": "_phone",
				"type": "string"
			}
		],
		"name": "createCustomer",
		"outputs": [
			{
				"name": "",
				"type": "bool"
			}
		],
		"payable": true,
		"stateMutability": "payable",
		"type": "function"
	},
	{
		"constant": false,
		"inputs": [],
		"name": "createOwner",
		"outputs": [],
		"payable": false,
		"stateMutability": "nonpayable",
		"type": "function"
	},
	{
		"constant": false,
		"inputs": [
			{
				"name": "_hashedEmail",
				"type": "string"
			},
			{
				"name": "_retailerName",
				"type": "string"
			},
			{
				"name": "_retailerLocation",
				"type": "string"
			}
		],
		"name": "createRetailer",
		"outputs": [
			{
				"name": "",
				"type": "uint256"
			}
		],
		"payable": true,
		"stateMutability": "payable",
		"type": "function"
	},
	{
		"constant": false,
		"inputs": [
			{
				"name": "_code",
				"type": "string"
			},
			{
				"name": "_retailer",
				"type": "string"
			},
			{
				"name": "_customer",
				"type": "string"
			}
		],
		"name": "initialOwner",
		"outputs": [
			{
				"name": "",
				"type": "bool"
			}
		],
		"payable": true,
		"stateMutability": "payable",
		"type": "function"
	},
	{
		"constant": false,
		"inputs": [
			{
				"name": "_code",
				"type": "string"
			},
			{
				"name": "_customer",
				"type": "string"
			}
		],
		"name": "reportStolen",
		"outputs": [
			{
				"name": "",
				"type": "bool"
			}
		],
		"payable": true,
		"stateMutability": "payable",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [
			{
				"name": "_customer",
				"type": "string"
			}
		],
		"name": "getCodes",
		"outputs": [
			{
				"name": "",
				"type": "string[]"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [
			{
				"name": "_code",
				"type": "string"
			}
		],
		"name": "getCustomerDetails",
		"outputs": [
			{
				"name": "",
				"type": "string"
			},
			{
				"name": "",
				"type": "string"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [
			{
				"name": "_code",
				"type": "string"
			}
		],
		"name": "getNotOwnedCodeDetails",
		"outputs": [
			{
				"name": "",
				"type": "string"
			},
			{
				"name": "",
				"type": "string"
			},
			{
				"name": "",
				"type": "uint256"
			},
			{
				"name": "",
				"type": "string"
			},
			{
				"name": "",
				"type": "string"
			},
			{
				"name": "",
				"type": "string"
			},
			{
				"name": "",
				"type": "string"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [
			{
				"name": "_code",
				"type": "string"
			}
		],
		"name": "getOwnedCodeDetails",
		"outputs": [
			{
				"name": "",
				"type": "string"
			},
			{
				"name": "",
				"type": "string"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [
			{
				"name": "_code",
				"type": "string"
			}
		],
		"name": "getretailerDetails",
		"outputs": [
			{
				"name": "",
				"type": "string"
			},
			{
				"name": "",
				"type": "string"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [],
		"name": "whoIsOwner",
		"outputs": [
			{
				"name": "",
				"type": "address"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	}
];

const address = '0xe1DfD8b9383B1C76f245F9BCA320D5854AFA47c9';

const contractInstance = new web3.eth.Contract(abiArray, address);

// const contractInstance = contract.at(address);

const getAccounts = async () => (
	await web3.eth.getAccounts()
);
// web3.eth.defaultAccount = web3.eth.getAccounts();

// This function generates a QR code
function generateQRCode() {
	return crypto.randomBytes(20).toString('hex');
}

// Hash password using bcrypt
function hashBcrypt(password) {
	return bcrypt.hashSync(password, saltRounds);
}

// Hash email using md5
function hashMD5(email) {
	return crypto.createHash('md5').update(email).digest('hex');
}

// Routes for webpages
app.use(express.static(__dirname + '/views'));
app.use(express.static(__dirname + '/views/davidshimjs-qrcodejs-04f46c6'));

// Manufacturer generates a QR Code here
app.get('/createCodes', (req, res) => {
	res.sendFile('views/createCodes.html', { root: __dirname });
});

// Creating a new retailer
app.get('/createRetailer', (req, res) => {
	res.sendFile('views/createRetailer.html', { root: __dirname });
});

// Main website which has 2 routers - manufacturer & retailer
app.get('/', (req, res) => {
	res.sendFile('views/index.html', { root: __dirname });
});


/**
 * Description: Adds a user to the database and to the blockchain
 * Request:     POST /signUp
 * Send:        JSON object which contains name, email, password, phone
 * Receive:     200 if successful, 400 otherwise
 */
app.post('/signUp', (req, res) => {
	console.log('Request to /signUp\n');
	let name = req.body.name;
	let email = req.body.email;
	let password = req.body.password;
	let phone = req.body.phone;
	let hashedPassword = hashBcrypt(password);
	console.log(`Email: ${email} \n`);
	// Adding the user in MySQL
	connection.query('SELECT * FROM USER WHERE Email = ? LIMIT 1', [email], (error, results) => {
		if (error) {
			console.log(error);
			return res.status(400);
		}
		if (results.length) {
			return res.status(400).send('Email already exists!');
		}
		connection.query('INSERT INTO USER VALUES (?,?,?,?)', [name, email, hashedPassword, phone], (error, results) => {
			if (error) {
				console.log(error);
				return res.status(400);
			}
			res.status(200).send('Signup successful!');
			// Adding user to the Blockchain
			hashedEmail = hashMD5(email);
			let ok = createCustomer(hashedEmail, name, phone);
			if (ok) {
				console.log(`User ${hashedEmail} successfully added to Blockchain!\n`);
			} else {
				console.log('ERROR! User could not be added to Blockchain.\n');
			}
		});
	});
});

// Add the user in Blockchain
function createCustomer(hashedEmail, name, phone) {
	return contractInstance.methods.createCustomer(hashedEmail, name, phone).send({ from: web3.eth.accounts[0], gas: 3000000 });
}


/**
 * Description: Login the user to the app
 * Request:     POST /login
 * Send:        JSON object which contains email, password
 * Receive:     200 if successful, 400 otherwise
 */
app.post('/login', (req, res) => {
	console.log('Request to /login\n');
	let email = req.body.email;
	let password = req.body.password;
	console.log(`Email: ${email} \n`);
	connection.query('SELECT * FROM USER WHERE Email = ? LIMIT 1', [email], (error, results) => {
		if (error) {
			console.log(error);
			return res.status(400);
		}
		console.log(results);
		if (results.length != 0) {
			connection.query('SELECT hashedPassword FROM USER WHERE Email = (?)', [email], (error, results) => {
				if (error) {
					console.log(error);
					return res.status(400);
				}
				let pass = results[0].hashedPassword;
				if (bcrypt.compareSync(password, pass)) {
					console.log(`Login successful with ${email} \n`);
					return res.status(200).send('Login successful!');
				}
				return res.status(400).send('Login failed.');
			});
		} else {
			console.log('Email does not exist!\n');
			return res.status(400).send('Email does not exist!');
		}
	});
});


/**
 * Description: Adds a retailer to the database and to the blockchain
 * Request:     POST /retailerSignUp
 * Send:        JSON object which contains name, email, password, location
 * Receive:     200 if successful, 400 otherwise
 */
app.post('/retailerSignup', (req, res) => {
	console.log('Request to /retailerSignup\n');
	let retailerEmail = req.body.email;
	let retailerName = req.body.name;
	let retailerLocation = req.body.location;
	let retailerPassword = req.body.password;
	let retailerHashedPassword = hashBcrypt(retailerPassword);
	let retailerHashedEmail = hashMD5(retailerEmail);
	console.log(`retailerEmail: ${retailerEmail}, hashedEmail: ${retailerHashedEmail} \n`);
	// Adding the retailer in MySQL
	connection.query('SELECT * FROM RETAILER WHERE retailerEmail = ? LIMIT 1', [retailerEmail], (error, results) => {
		if (error) {
			console.log(error);
			return res.status(400).send('Some SQL Error');
		}
		if (results.length) {
			return res.status(400).send('Email already exists!');
		}
		connection.query('INSERT INTO RETAILER VALUES (?,?,?,?)', [retailerName, retailerEmail, retailerLocation,
			retailerHashedPassword], (error, results) => {
				if (error) {
					console.log(error);
					return res.status(400).send('Some SQL Error');
				}
				// Adding retailer to Blockchain
				let ok = createRetailer(retailerHashedEmail, retailerName, retailerLocation);
				if (ok) {
					console.log(`Retailer ${retailerHashedEmail} successfully added to Blockchain!\n`);
					return res.status(200).send('Retailer successfully added');
				}
				console.log('ERROR! Retailer could not be added to Blockchain.\n');
				return res.status(400).send('Adding Retailer Unsuccessful');
			});
	});
});

// Add retailer to Blockchain
const createRetailer = async (retailerHashedEmail, retailerName, retailerLocation) => {
	let account = await getAccounts();
	return contractInstance.methods.createRetailer(retailerHashedEmail, retailerName, retailerLocation).send({ from: account[0], gas: 3000000 });
}


/**
 * Description: Login the retailer to the app
 * Request:     POST /retailerLogin
 * Send:        JSON object which contains email, password
 * Receive:     200 if successful, 400 otherwise
 */
app.post('/retailerLogin', (req, res) => {
	console.log('Request to /retailerLogin\n');
	let retailerEmail = req.body.email;
	let retailerPassword = req.body.password;
	console.log(`Email: ${retailerEmail} \n`);
	connection.query('SELECT retailerHashedPassword FROM RETAILER WHERE retailerEmail = ?', [retailerEmail], (error, results) => {
		if (error) {
			console.log(error);
			return res.status(400);
		}
		let pass = results[0].retailerHashedPassword;
		if (bcrypt.compareSync(retailerPassword, pass)) {
			console.log(`${retailerEmail} has successfully logged in\n`);
			return res.status(200).send('Retailer login successful!');
		}
		console.log(`${retailerEmail} COULD NOT login\n`);
		return res.status(400).send('Retailer login failed.');
	})
});


/**
 * Description: Get reatiler details
 * Request:     GET /retailerDetails
 * Send:
 * Receive:     JSON object of retailer details if successful, 400 otherwise
 */
app.get('/retailerDetails', (req, res) => {
	connection.query('Select * from RETAILER', (error, results) => {
		if (error) {
			console.log(error);
			return res.status(400).send('ERROR');
		}
		console.log(`Retailer details are:\n ${results} \n`);
		return res.status(400).send(JSON.parse(JSON.stringify(results)));
	})
});


/**
 * Description: Add retailer to code
 * Request:     POST /addRetailerToCode
 * Send:        JSON object which contains code, email
 * Receive:     200 if successful, 400 otherwise
 */
app.post('/addRetailerToCode', (req, res) => {
	console.log('Request to /addRetailerToCode\n');
	let code = req.body.code;
	let retailerEmail = req.body.email;
	let hashedEmail = hashMD5(retailerEmail);
	console.log(`retailerEmail: ${retailerEmail}, hashed email: ${hashedEmail} \n`);
	let ok = contractInstance.methods.addRetailerToCode(code, hashedEmail).call();
	if (!ok) {
		return res.status(400).send('Error');
	}
	console.log(`Successfully added ${hashedEmail} to code ${code} \n`);
	return res.status(200).send('Success');
});


/**
 * Description: Lists all the assets owned by the user
 * Request:     POST /myAssets
 * Send:        JSON object which contains email
 * Receive:     JSON array of objects which contain brand, model, description, status, manufacturerName,manufacturerLocation,
 *                                                  manufacturerTimestamp, retailerName, retailerLocation, retailerTimestamp
 */
app.post('/myAssets', (req, res) => {
	console.log('Request to /myAssets\n');
	let myAssetsArray = [];
	let email = req.body.email;
	let hashedEmail = hashMD5(email);
	let arrayOfCodes = contractInstance.methods.getCodes(hashedEmail).call();
	console.log(`Email ${email}`);
	console.log(`Customer has these product codes: ${arrayOfCodes} \n`);
	for (code in arrayOfCodes) {
		let ownedCodeDetails = contractInstance.methods.getOwnedCodeDetails(arrayOfCodes[code]).call();
		let notOwnedCodeDetails = contractInstance.methods.getNotOwnedCodeDetails(arrayOfCodes[code]).call();
		myAssetsArray.push({
			'code': arrayOfCodes[code], 'brand': notOwnedCodeDetails[0],
			'model': notOwnedCodeDetails[1], 'description': notOwnedCodeDetails[2],
			'status': notOwnedCodeDetails[3], 'manufacturerName': notOwnedCodeDetails[4],
			'manufacturerLocation': notOwnedCodeDetails[5], 'manufacturerTimestamp': notOwnedCodeDetails[6],
			'retailerName': ownedCodeDetails[0], 'retailerLocation': ownedCodeDetails[1],
			'retailerTimestamp': ownedCodeDetails[2]
		});
	}
	res.status(200).send(JSON.parse(JSON.stringify(myAssetsArray)));
});


/**
 * Description: Lists all the assets owned by the user
 * Request:     POST /stolen
 * Send:        JSON object which contains code, email
 * Receive:     200 if product status was changed, 400 otherwise.
 */
app.post('/stolen', (req, res) => {
	console.log('Request to /stolen\n');
	let code = req.body.code;
	let email = req.body.email;
	let hashedEmail = hashMD5(email);
	console.log(`Email: ${email} \n`);
	let ok = contractInstance.methods.reportStolen(code, hashedEmail).call();
	if (!ok) {
		console.log(`ERROR! Code: ${code} status could not be changed.\n`);
		return res.status(400).send('ERROR! Product status could not be changed.');
	}
	console.log(`Product code ${code} successfully changed!\n`);
	res.status(200).send('Product status successfully changed!');
});


// This array keeps track of all the QR Codes in use
const QRCodes = [];

/**
 * Description: Sell a product from myAssets (aka your inventory)
 * Request:     POST /sell
 * Send:        JSON object which contains code, sellerEmail
 * Receive:     List of QR Codes owned by the seller if successful, 400 otherwise
 */
app.post('/sell', (req, res) => {
	console.log('Request to /sell\n');
	let code = req.body.code;
	let sellerEmail = req.body.email;
	console.log(`Email ${sellerEmail} \n`);
	hashedSellerEmail = hashMD5(sellerEmail);
	let currentTime = Date.now();         // Date.now() gets the current time in milliseconds
	let QRCode = generateQRCode();
	let QRCodeObj = {
		'QRCode': QRCode, 'currentTime': currentTime, 'sellerEmail': sellerEmail, 'buyerEmail': '',
		'code': code, 'confirm': '0', 'retailer': '0'
	};
	QRCodes.push(QRCodeObj);
	console.log(`Session created ${(JSON.stringify(QRCode))} \n`);
	res.status(200).send(JSON.parse(JSON.stringify(QRCode)));
});


/**
 * Description: Buy a product
 * Request:     POST /buy
 * Send:        JSON object which contains QRCode, email
 * Receive:     200 if successful, 400 otherwise
 */
app.post('/buy', (req, res) => {
	console.log('Request to /buy\n');
	let QRCode = req.body.QRCode;
	let buyerEmail = req.body.email;
	let currentTime = Date.now();         // Date.now() gets the current time in milliseconds
	console.log(`Email: ${buyerEmail} \n`);
	for (let i = 0; i < QRCodes.length; i++) {
		if (QRCode === QRCodes[i]['QRCode']) {
			let timeElapsed = Math.floor((currentTime - QRCodes[i]['currentTime']) / 1000);
			// QR Codes are valid only for 600 secs
			if (timeElapsed <= 600) {
				QRCodes[i]['buyerEmail'] = buyerEmail;
				console.log(`QRCode matches, Session updated ${(JSON.stringify(QRCode))} \n`);
				return res.status(200).send('Validated!');
			}
			console.log('Time out error\n');
			return res.status(400).send('Timed out!');
		}
	}
	console.log('Could not find QRCode\n');
	return res.status(400).send('Could not find QRCode');
});


/**
 * Description: Get product details
 * Request:     POST /getProductDetails
 * Send:        JSON object which contains code
 * Receive:     JSON object whcih contains brand, model, description, status, manufacturerName, manufacturerLocation,
 *                                         manufacturerTimestamp, retailerName, retailerLocation, retailerTimestamp
 */
app.post('/getProductDetails', (req, res) => {
	console.log('Request to /getProductDetails\n');
	let code = req.body.code;
	let QRCode = req.body.QRCode;
	let currentTime = Date.now();         // Date.now() gets the current time in milliseconds
	for (let i = 0; i < QRCodes.length; i++) {
		if (QRCode === QRCodes[i]['QRCode']) {
			let timeElapsed = Math.floor((currentTime - QRCodes[i]['currentTime']) / 1000);
			// QR Codes are valid only for 600 secs
			if (timeElapsed <= 600) {
				let ownedCodeDetails = contractInstance.methods.getOwnedCodeDetails(code).call();
				let notOwnedCodeDetails = contractInstance.methods.getNotOwnedCodeDetails(code).call();
				if (!ownedCodeDetails || !notOwnedCodeDetails) {
					return res.status(400).send('Could not retrieve product details.');
				}
				let productDetails = {
					'brand': notOwnedCodeDetails[0], 'model': notOwnedCodeDetails[1], 'description': notOwnedCodeDetails[2],
					'status': notOwnedCodeDetails[3], 'manufacturerName': notOwnedCodeDetails[4],
					'manufacturerLocation': notOwnedCodeDetails[5], 'manufacturerTimestamp': notOwnedCodeDetails[6],
					'retailerName': ownedCodeDetails[0], 'retailerLocation': ownedCodeDetails[1],
					'retailerTimestamp': ownedCodeDetails[2]
				};
				console.log('QRCode matched\n');
				return res.status(200).send(JSON.parse(JSON.stringify(productDetails)));
			}
			console.log('Time out error\n');
			return res.status(400).send('Timed out!');
		}
	}
});


/**
 * Description: Seller confirms deal and gets registered as new owner on the Blockchain
 * Request:     POST /sellerConfirm
 * Send:        JSON object which contains email, QRCode, retailer
 * Receive:     200 if successful, 400 otherwise
 */
app.post('/sellerConfirm', (req, res) => {
	console.log('Request to /sellerConfirm\n');
	let sellerEmail = req.body.email;
	let QRCode = req.body.QRCode;
	let retailer = req.body.retailer;
	console.log(`Email: ${sellerEmail} \n`);
	let currentTime = Date.now();         // Date.now() gets the current time in milliseconds
	let sellerHashedEmail = hashMD5(sellerEmail);
	for (let i = 0; i < QRCodes.length; i++) {
		if (QRCode === QRCodes[i]['QRCode']) {
			let timeElapsed = Math.floor((currentTime - QRCodes[i]['currentTime']) / 1000);
			// QR Codes are valid only for 600 secs
			if (timeElapsed <= 600) {
				QRCodes[i]['confirm'] = '1';
				if (retailer === '1') {
					QRCodes[i]['retailer'] = '1';
				}
				console.log('Success in sellerConfirm\n');
				return res.status(200).send('Seller confirmed!');
			}
			console.log('Time out error\n');
			return res.status(400).send('Timed out!');
		}
	}
	console.log('Could not find QRCodes\n');
	return res.status(400).send('Could not find QRCodes');
});


/**
 * Description: Buyer confirms deal
 * Request:     POST /buyerConfirm
 * Send:        JSON object which contains email, QRCode
 * Receive:     200 if successful, 400 otherwise
 */
app.post('/buyerConfirm', (req, res) => {
	console.log('Request made to /buyerConfirm\n');
	let buyerEmail = req.body.email;
	let QRCode = req.body.QRCode;
	let currentTime = Date.now();         // Date.now() gets the current time in milliseconds
	console.log(`Email: ${buyerEmail} and QRCode: ${QRCode} \n`);
	for (let i = 0; i < QRCodes.length; i++) {
		if (QRCode === QRCodes[i]['QRCode']) {
			let timeElapsed = Math.floor((currentTime - QRCodes[i]['currentTime']) / 1000);
			// QR Codes are valid only for 600 secs
			if (timeElapsed <= 600) {
				if (QRCodes[i]['confirm'] === '1') {
					let hashedSellerEmail = hashMD5(QRCodes[i]['sellerEmail']);
					let hashedBuyerEmail = hashMD5(QRCodes[i]['buyerEmail']);
					let code = QRCodes[i]['code'];
					var ok;
					if (QRCodes[i]['retailer'] === '1') {
						console.log('Performing transaction for retailer\n');
						ok = contractInstance.methods.initialOwner(code, hashedSellerEmail, hashedBuyerEmail).send({ from: web3.eth.accounts[0], gas: 3000000 });
					} else {
						console.log('Performing transaction for customer\n');
						ok = contractInstance.methods.changeOwner(code, hashedSellerEmail, hashedBuyerEmail).send({ from: web3.eth.accounts[0], gas: 3000000 });
					}
					if (!ok) {
						return res.status(400).send('Error');
					}
					console.log('Success in buyerConfirm, transaction is done!\n');
					return res.status(200).send('Ok');
				}
				console.log('Buyer has not confirmed\n');
			}
			return res.status(400).send('Timed out!');
		}
	}
	console.log('Product not found\n')
	return res.status(400).send('Product not found');
});

// Function that creates an initial owner for a product
function initialOwner(code, retailerHashedEmail, customerHashedEmail) {
	return contractInstance.methods.initialOwner(code, retailerHashedEmail, customerHashedEmail).send({ from: web3.eth.accounts[0], gas: 3000000 });
}

// Function that creates transfers ownership of a product
function changeOwner(code, oldOwnerHashedEmail, newOwnerHashedEmail) {
	return contractInstance.methods.changeOwner(code, oldOwnerHashedEmail, newOwnerHashedEmail).send({ from: web3.eth.accounts[0], gas: 3000000 });
}


/**
 * Description: Gives product details if the scannee is not the owner of the product
 * Request:     POST /scan
 * Send:        JSON object which contains code
 * Receive:     JSON object which has productDetails
 */
app.post('/scan', (req, res) => {
	console.log('Request made to /scan\n');
	let code = req.body.code;
	let productDetails = contractInstance.methods.getNotOwnedCodeDetails(code).call();
	let productDetailsObj = {
		'name': productDetails[0], 'model': productDetails[1], 'status': productDetails[2],
		'description': productDetails[3], 'manufacturerName': productDetails[4],
		'manufacturerLocation': productDetails[5], 'manufacturerTimestamp': productDetails[6]
	};
	console.log(`Code ${code} \n`);
	res.status(200).send(JSON.stringify(productDetailsObj));
});


/**
 * Description: Generates QR codes for the manufacturers
 * Request:     POST /QRCodeForManufacturer
 * Send:        JSON object which contains brand, model, status, description, manufacturerName, manufacturerLocation
 * Receive:     200 if QR code was generated, 400 otherwise.
 */
app.post('/QRCodeForManufacturer', async (req, res) => {
	console.log('Request to /QRCodeForManufacturer\n');
	let brand = req.body.brand;
	let model = req.body.model;
	let status = 0;
	let description = req.body.description;
	let manufacturerName = req.body.manufacturerName;
	let manufacturerLocation = req.body.manufacturerLocation;
	let manufacturerTimestamp = new Date();         // Date() gives current timestamp
	manufacturerTimestamp = manufacturerTimestamp.toISOString().slice(0, 10);
	let salt = crypto.randomBytes(20).toString('hex');
	let code = hashMD5(brand + model + status + description + manufacturerName + manufacturerLocation + salt);
	let account = await getAccounts();
	let ok = contractInstance.methods.createCode(code, brand, model, status, description, manufacturerName, manufacturerLocation, manufacturerTimestamp).send({ from: account[0], gas: 3000000 });
	console.log(`Brand: ${brand} \n`);
	if (!ok) {
		return res.status(400).send('ERROR! QR Code for manufacturer could not be generated.');
	}
	console.log(`The QR Code generated is: ${code} \n`);
	let QRcode = code + '\n' + brand + '\n' + model + '\n' + description + '\n' + manufacturerName + '\n' + manufacturerLocation;
	fs.writeFile('views/davidshimjs-qrcodejs-04f46c6/code.txt', QRcode, (err, QRcode) => {
		if (err) {
			console.log(err);
		}
		console.log('Successfully written QR code to file!\n');
	});
	res.sendFile('views/davidshimjs-qrcodejs-04f46c6/index.html', { root: __dirname });
});


/**
 * Description: Gives all the customer details
 * Request:     GET /getCustomerDetails
 * Send:        JSON object which contains email
 * Receive:     JSON object which contains name, phone
 */
app.get('/getCustomerDetails', (req, res) => {
	console.log('Request to /getCustomerDetails\n');
	let email = req.body.email;
	let hashedEmail = hash(email);
	let customerDetails = contractInstance.methods.getCustomerDetails(hashedEmail).call();
	console.log(`Email: ${email} \n`);
	let customerDetailsObj = {
		'name': customerDetails[0], 'phone': customerDetails[1]
	};
	res.status(200).send(JSON.parse(JSON.stringify(customerDetailsObj)));
});

// Server start
app.listen(port, (req, res) => {
	console.log(`Listening to port ${port}...\n`);
});