phone.js

const {MongoClient} = require('mongodb');
const MONGODB_URI = 'mongodb://localhost:27017/KoalatyEconomy';
const LOWEST_NUMBER = '0000000';
const MAX_NUMBER = 9999999;
const MAX_BATCH_SIZE = 98000;
const AREA_CODES = [420, 469];

const generateNumbers = (area_codes) => {
    let numbers = [];

    for (let index = 0; index < area_codes.length; index++) {
        area_codes[index] = parseInt(`${area_codes[index]}${LOWEST_NUMBER}`);
    }

    for (let count = 0; (count + parseInt(LOWEST_NUMBER)) < MAX_NUMBER; count++) {
        area_codes.forEach(code => {
            numbers.push(code + count);
        });
    }

    return numbers;
};

const shuffle = (array) => {
    for (let i = array.length - 1; i > 0; i--) {
        let j = Math.floor(Math.random() * (i + 1));
        [array[i], array[j]] = [array[j], array[i]];
    }
};


const connect = async () => {
    return await MongoClient.connect(MONGODB_URI, {
        useNewUrlParser: true,
        useUnifiedTopology: true
    });
};

connect()
    .then(async mongodb_client => {
        let numbers = generateNumbers(AREA_CODES);
        let run = true;

        console.log(numbers.length.toLocaleString() + ' generated...');

        shuffle(numbers);

        try {
            const collection = mongodb_client.db().collection('phone_numbers');
            let c = 1;

            await collection.createIndex({number: 1}, {unique: true});
            await collection.createIndex({assigned: 1});

            while (run) {
                let batch = numbers.slice(0, MAX_BATCH_SIZE);
                numbers = numbers.slice(MAX_BATCH_SIZE);

                if (batch.length === 0) {
                    run = false;
                    continue;
                }

                console.log(`Inserting batch #${c} [${batch.length.toLocaleString()}]. Approximately ${Math.ceil(numbers.length / MAX_BATCH_SIZE)} batches left...`);

                for (let index = 0; index < batch.length; index++) {
                    batch[index] = {number: batch[index], assigned: false};
                }

                console.time(`Batch #${c} completed...`);
                await collection.insertMany(batch);
                console.timeEnd(`Batch #${c} completed...`);
                c++;
            }
        } finally {
            await mongodb_client.close();
        }
    })
    .catch(error => {
        console.log(error);
    });