server.js

const Hapi = require('@hapi/hapi');
const MongoClient = require('mongodb').MongoClient;

const server = Hapi.server({
    port: 3000,
    debug: {
        request: ['*']
    }
});

const routes = [
    {
        method: 'GET',
        path: '/locations',
        handler: async (request, h) => {

            const db = server.app.db;
            const locationCollection = db.collection('locations');

            // query all locations
            const documents = await locationCollection.find({}).toArray();
            return documents;
        }
    },
    {
        method: 'GET',
        path: '/locations/{locationId}/items',
        handler: async (request, h) => {

            const locationId = Number(request.params.locationId)

            const db = server.app.db;
            const locationCollection = db.collection('locations');

            const location = await locationCollection.findOne({ locationId: locationId })
            if (location === null) {
                return h.response().code(404)
            }

            const itemsCollection = db.collection('items')
            const items = await itemsCollection.find({ locationId: locationId }).toArray()

            return items
        },
    },
    {
        method: 'POST',
        path: '/locations/{locationId}/order',
        handler: async (request, h) => {

            const db = server.app.db;
            const ordersCollection = db.collection('orders');

            await ordersCollection.insertOne(request.payload)

            const savedOrder = await ordersCollection.findOne({ customerId: request.payload.customerId });

            const itemsIds = savedOrder.items.map((item) => {
                return item.itemId
            })

            const items = await db.collection('items').find({ itemId: { $in: itemsIds } }).toArray()

            let total = 0

            for (index in items) {
                const payloadItem = savedOrder.items.find((x) => {
                    if (x.itemId === items[index].itemId) {
                        return x
                    }
                })

                total = total + (payloadItem.quantity * items[index].price)
            }

            savedOrder.total = total

            return h.response(savedOrder).code(201)
        },
    }
];

const init = async () => {

    // connect to DB
    const url = 'mongodb://localhost:27017/local-grocery-store';
    const client = new MongoClient(url, { useNewUrlParser: true, useUnifiedTopology: true });
    await client.connect();

    const db = client.db();
    server.app.db = db;

    console.log("Connected successfully to mongo");

    // routes configuration
    server.route(routes);

    try {
        if (!module.parent) {
            await server.start();
        }
        else {
            await server.initialize();
        }
        return server;
    }
    catch (error) {
        console.error(error);
        process.exit(1);
    }
};

process.on('unhandledRejection', (err) => {

    console.log(err);
    process.exit(1);
});

void async function () {
    if (!module.parent) {
        await init();
    }
}();

module.exports = {
    init
}