index.js

const puppeteer = require('puppeteer');
const util = require('util');
const moment = require('moment');
const notif = require('./notification.js');

const locationIdToName = {
    '89': 'Calgary',
    '90': 'Halifax',
    '91': 'Montréal',
    '92': 'Ottawa',
    '93': 'Québec',
    '94': 'Toronto',
    '95': 'Vancouver',
};


protoLink = 'https://ais.usvisa-info.com/en-ca/niv/schedule/%s/appointment/days/%s.json?appointments[expedite]=false';

const queryNumber = process.env.QUERYNO;
const email = process.env.EMAIL;
const password = process.env.PASSWORD;
const intervalMinute = parseInt(process.env.INTERVAL || '30');
const interval = intervalMinute * 60 * 1000;
const lower = parseInt(process.env.LOWER || '7');
const upper = parseInt(process.env.UPPER || '365');

const sender = process.env.SENDER;
const senderPswd = process.env.SENDERPSWD;
const receivers = JSON.parse(process.env.RECEIVERS);
const emailNotif = new notif.EmailNotification(sender, senderPswd, receivers);

async function drainTheSwamp() {
    const startTime = moment();
    console.log(`------------------------------------- Start processing at [${startTime.format()}]`)
    console.log(`Looking for available appts at range (${lower}, ${upper}) days from today(exclusive), every ${intervalMinute} minutes`);

    let browser;
    try {
        browser = await puppeteer.launch({
            headless: false,
            args:[
            '--start-maximized'
            ],
            executablePath: '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome' // MACOS chrome
            // executablePath: '/usr/bin/chromium-browser' // Raspberry Pi chromium
        });
        const page = await browser.newPage();

        await gotoSignInPage(page);
        await login(page);

        let retry = 5;
        while (!page.url().includes('groups') && retry > 0) {
            console.error(`[ERROR] Retrying after getting page url: ${page.url()}`);
            retry -= 1;
            await sleep(10000);
            await gotoSignInPage(page);
            await login(page);
        }
        if (retry === 0) {
            console.error(`[ERROR] All retries are exhausted! Current page url: ${page.url()}`);
        }

        const surpriseList = await getSurprises(page);

        deliverNotification(surpriseList);
        
    } catch (error) {
        console.error(`[ERROR] ${error}`);
    } finally {
        if (browser) {
            await browser.close();
        }
    }

    const endTime = moment();
    const durationSec = moment.duration(endTime.diff(startTime)).asSeconds();
    console.log(`------------------------------------- End processing at [${endTime.format()}], takes ${durationSec}s`);
    console.log('');

    setTimeout(drainTheSwamp, interval);
}

function sleep (time) {
    return new Promise((resolve) => setTimeout(resolve, time));
}

async function gotoSignInPage(page) {
    await page.setUserAgent('Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.125 Safari/537.36');
    await page.setViewport({ width: 1920, height: 1080});
    await page.goto('https://ais.usvisa-info.com/en-ca/niv/users/sign_in', { waitUntil: 'networkidle0' });
}

async function login(page) {
    await page.type('#user_email', email);
    await page.type('#user_password', password);
    await page.evaluate(() => {
        document.querySelector('#policy_confirmed').click();
    });
    await page.evaluate(() => {
        document.querySelector('input.button.primary').click();
    });
    await page.waitForNavigation({
        waitUntil: 'networkidle0',
    });
}

async function getSurprises(page) {
    let surpriseList = [];
    for (const [locationId, locationName] of Object.entries(locationIdToName)) {

        const url = util.format(protoLink, queryNumber, locationId);
        const resJsonStr = await page.evaluate(async (url) => {
            const response = await fetch(url);
            if (response.status !== 200) {
                console.error(`[ERROR] get response code: ${response.status}, response text: ${response.text()}`);
                return '[]';
            }
            const jsonStr = await response.text();
            return jsonStr;
        }, url);

        try {
            const resJson = JSON.parse(resJsonStr);
            for (const dateObject of resJson) {
                const d = moment(dateObject['date']);
                const lowerDate = moment().add(lower, 'days');
                const upperDate = moment().add(upper, 'days');
    
                if (lowerDate < d && d < upperDate) {
                    surpriseList.push({
                        'location': locationName,
                        'date': dateObject['date']
                    });
                }
            }

        } catch (error) {
            console.error(`[ERROR] ${error}`);
            console.error(`[ERROR] caused by json string: ${resJsonStr}`);
        }
    }
    return surpriseList;
}

function deliverNotification(surpriseList) {
    if (surpriseList.length !== 0) {
        for (const surprise of surpriseList) {
            notif.consoleNotify(surprise.location, surprise.date);
        }
        notif.soundNotify().then(() => {});
        emailNotif
            .notify(JSON.stringify(surpriseList))
            .then(function(result, error) {
                if (error) {
                    console.error(`[ERROR] ${error}`);
                } else {
                    console.log('Email sent: ' + result.response);
                }
            }).catch(function(error) {
                console.error(`[ERROR] ${error}`);
            });
    }
}

drainTheSwamp();