'use strict';

const MongoClient = require('mongodb').MongoClient;

const URL = '<MONGO URL>'; // topology does not matter
const MONGO_OPTS = {poolSize: 5, useUnifiedTopology: true};
const NUM_QUERIES = 512;

(async function() {
    const connection = await MongoClient.connect(URL, MONGO_OPTS);
    const collection = connection.db('ec').collection('groups');

    const promises = [];

    let queriesLeft = NUM_QUERIES;
    while (queriesLeft-- > 0) promises.push(makeQuery(collection));

    const start = Date.now();
    const results = await Promise.all(promises);
    results.sort((a, b) => a - b);

    const sumTime = results.reduce((r, a) => r + a, 0);
    const averageTime = Math.round(sumTime / results.length);
    const medianTime = results[Math.round(results.length / 2)];
    const minTime = results[0];
    const maxTime = results[results.length -1];

    console.log(`Queries: MIN: ${minTime}ms, MAX: ${maxTime}ms, AVG: ${averageTime}ms, MEDIAN: ${medianTime}ms, SUM: ${sumTime}ms`);
    console.log(`Script: ${Date.now() - start}ms`);

    connection.close();
}());

async function makeQuery(collection) {
    const start = Date.now();
    await collection.findOne({_id: `a${randomInt(1, 10000)}`});
    return Date.now() - start;
}

function randomInt(min, max) {
    return ((Math.random() * (max - min)) | 0) + min;
}