server.js

/* eslint-disable no-unused-expressions */
/**
 * e-amusement Maintenance Bot
 * server.js
 * authored by twitter/@anericzhang
 * creation date: 10/10/22
 * repository: https://github.com/theericzhang/eamuse-maintenance-bot
 */

import { TwitterApi } from 'twitter-api-v2';
import express from 'express';
import 'dotenv/config';

const app = express();

// expecting json
app.use(express.json());

app.get('/', (req, res) => {
    res.send('twitter-eamuse-warn');
});

app.listen(process.env.PORT || 5000, () => {
    console.log('App listening');
});

// create a Twitter client with apikey+secret & accesstoken+secret
// twitter account with elevated developer permissions is REQUIRED to use v1.tweet() functions
// https://developer.twitter.com/en/docs/twitter-api/v1/tweets/post-and-engage/api-reference/post-statuses-update
const clientMain = new TwitterApi(
    {
        appKey: process.env.TWITTER_API_KEY,
        appSecret: process.env.TWITTER_API_SECRET,
        accessToken: process.env.TWITTER_ACCESS_TOKEN,
        accessSecret: process.env.TWITTER_ACCESS_TOKEN_SECRET,
    },
);

// these key values will set to true once time conditions are met
// with these "use once" flags, we can make sure we are posting a tweet once during a monthly lifecycle
// once all values are true, we know to reset the object back to its original state
const extendedMaintenancePostedFlags = {
    posted3DayWarning: false,
    posted24HourWarning: false,
    posted2HourWarning: false,
    postedBeginsWarning: false,
    postedEndsIn1HourNotice: false,
    postedEndedNotice: false,
};

/**
 * Resets all truth flags used to guard the postTweet() function.
 * @returns {void} - all truth flags from extendedMaintenancePostedFlags will be set to false
 */
function resetFlags() {
    // eslint-disable-next-line no-return-assign
    Object.keys(extendedMaintenancePostedFlags).forEach((flag) => extendedMaintenancePostedFlags[flag] = false);
}

// declare reusable options object when .toLocaleTimeString() is called
const toLocaleTimeStringOptionsVerbose = {
    timeZone: 'America/New_York',
    year: 'numeric',
    month: '2-digit',
    day: '2-digit',
    hour: '2-digit',
    minute: '2-digit',
};

const toLocaleTimeStringOptionsShortET = {
    timeZone: 'America/New_York',
    hour: '2-digit',
    minute: '2-digit',
};

const toLocaleTimeStringOptionsShortPT = {
    timeZone: 'America/Los_Angeles',
    hour: '2-digit',
    minute: '2-digit',
};

const toLocaleDateStringOptions = {
    timeZone: 'America/New_York',
    year: 'numeric',
    month: '2-digit',
    day: '2-digit',
};

// prevent edits to locale options
Object.freeze(toLocaleTimeStringOptionsVerbose);
Object.freeze(toLocaleTimeStringOptionsShortET);
Object.freeze(toLocaleTimeStringOptionsShortPT);
Object.freeze(toLocaleDateStringOptions);

/**
 * Returns a relevant warning tweet message for the Twitter Client to post
 * @param {number} index - The message bank contains an array of premade tweets to send. Specify an index to select the message
 * @param {string} dateOfMaintenance - The start date of the maintenance day, passed as a string. must be passed as .toLocaleString('en-US', toLocaleDateStringOptions)
 * @param {Date} timeStart - The time that extended maintenance starts. Must be passed as a pure date object
 * @param {Date} timeEnd - The time that extended maintenance ends. Must be passed as a pure date object
 * @returns {string} - Parsed message that contains the relevant time to the message
 */
function getMessage(index, dateOfMaintenance, timeStart, timeEnd) {
    const tweetBodyBank = [
        `⚠️ Warning - In THREE days, the e-amusement Service will be undergoing extended maintenance:\n\nMonday, ${dateOfMaintenance}\nBegins: ${timeStart.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortET)} ET / ${timeStart.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortPT)} PT \nEnds: ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortET)} ET / ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortPT)} PT`,
        `⚠️ Warning - The e-amusement Service will be undergoing extended maintenance TOMORROW:\n\nMonday, ${dateOfMaintenance}\nBegins: ${timeStart.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortET)} ET / ${timeStart.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortPT)} PT \nEnds: ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortET)} ET / ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortPT)} PT`,
        `🚨 Alert - In TWO hours, the e-amusement Service will be starting extended maintenance:\n\nBegins: ${timeStart.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortET)} ET / ${timeStart.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortPT)} PT \nEnds: ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortET)} ET / ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortPT)} PT`,
        `🚨 Alert - The e-amusement Service has started extended maintenance. e-amusement is expected to be back online at ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortET)} ET / ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortPT)} PT`,
        `⚠️ Notice - The e-amusement Service is expected to be back online in ONE hour, at ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortET)} ET / ${timeEnd.toLocaleTimeString('en-US', toLocaleTimeStringOptionsShortPT)} PT`,
        '✅ Notice - The e-amusement Service is expected to be back online now',
    ];
    return tweetBodyBank[index];
}

let isCurrentlyPosting = false;

/**
 * Helper function to post tweetBody. This function is called when all timing conditions are met
 * @param {string} tweetBody - The Tweet body message to be sent to Twitter
 */

async function postTweet(tweetBody) {
    isCurrentlyPosting = true;
    await clientMain.v1.tweet(tweetBody);
    console.log('Posted! - ', tweetBody);
    console.log('Flags - ', extendedMaintenancePostedFlags);
    isCurrentlyPosting = false;
}

// key observer function that handles date + time checking for extended maintenance periods

/**
 * extendedMaintenanceObserver is called every 6 seconds to create a current Date object to compare to
 * the expected Extended Maintenance day. Extended Maintenance falls on every third Tuesday from 02:00 to 07:00 JST,
 * which falls on the Monday prior from 12:00 - 17:00 EST.
 * @returns {void}. Sends a Tweet to the eamuse_schedule Twitter account.
 */

async function extendedMaintenanceObserver() {
    let tweetBody = '';
    const referenceDate = new Date();
    const timezoneOffsetJapanUTC = 9;

    // adding 9 to hour count to reflect JST
    referenceDate.setUTCHours(referenceDate.getUTCHours() + timezoneOffsetJapanUTC);
    referenceDate.setUTCDate(1);
    // console.log('reference date before finding tuesday - expected to be the 1st every time: ' ,referenceDate);

    // finds first tuesday and sets referenceDate to it
    while (referenceDate.getUTCDay() !== 2) {
        referenceDate.setUTCDate(referenceDate.getUTCDate() + 1);
    }
    // console.log('reference date after finding tuesday - expected to be the first tuesday every time: ',referenceDate);

    // getting extended maintenance day, which is the third tuesday in Japan. Just add 14 to our recently set referenceDate
    const extendedMaintenanceDay = new Date(referenceDate.setUTCDate(referenceDate.getUTCDate() + 14));
    // console.log('extended maintenance day in JP', extendedMaintenanceDay);

    // create new time object representing current time in JST
    const currentDate = new Date();
    currentDate.setHours(currentDate.getHours() + timezoneOffsetJapanUTC);
    // console.log('current time in JP', currentDate);

    // begin date comparisons - Because our extendedMaintenanceDay date object is set on the third tuesday, we can reference our currentDate object to post warnings
    // when getting values, it is mandatory to getUTC__, otherwise it will show in UTC +0 values
    // calling getUTC__ will provide us with time local to Japan, UTC +9
    const is3DaysBeforeExtendedMaintenance = extendedMaintenanceDay.getUTCFullYear() === currentDate.getUTCFullYear()
                                          && extendedMaintenanceDay.getUTCMonth() === currentDate.getUTCMonth()
                                          && (extendedMaintenanceDay.getUTCDate() - currentDate.getUTCDate() === 3)
                                          && (extendedMaintenanceDay.getUTCHours() === 0)
                                          && (extendedMaintenanceDay.getUTCMinutes() === 0);
    const is1DayBeforeExtendedMaintenance = extendedMaintenanceDay.getUTCFullYear() === currentDate.getUTCFullYear()
                                          && extendedMaintenanceDay.getUTCMonth() === currentDate.getUTCMonth()
                                          && (extendedMaintenanceDay.getUTCDate() - currentDate.getUTCDate() === 1)
                                          && (extendedMaintenanceDay.getUTCHours() === 0)
                                          && (extendedMaintenanceDay.getUTCMinutes() === 0);
    const isTodayExtendedMaintenance = extendedMaintenanceDay.getUTCFullYear() === currentDate.getUTCFullYear()
                                    && extendedMaintenanceDay.getUTCMonth() === currentDate.getUTCMonth()
                                    && extendedMaintenanceDay.getUTCDate() === currentDate.getUTCDate();

    /**
     * begin time comparisons - Because the time portion to extendedMaintenanceDay is set in JST, we can manually check to see if the hours fall on maintenance times
     * extended maintenance happens from 2am-7am JST
     * an additional condition, isPastExtendedMaintenance is needed to determine if all the flags are safe to reset
     * flags are used to guard the postTweet() function. if a tweet has not been posted yet, its flag value will be false.
     * after a tweet has been posted, the flag value will be set to true.
     * the next time the extendedMaintenanceObserver() will be run, postTweet() will not be run again.
     */

    const is2HoursBeforeExtendedMaintenance = isTodayExtendedMaintenance && (extendedMaintenanceDay.getUTCHours() === 0 && extendedMaintenanceDay.getUTCMinutes() === 0);
    const isExactlyExtendedMaintenance = isTodayExtendedMaintenance && (extendedMaintenanceDay.getUTCHours() === 2 && extendedMaintenanceDay.getUTCMinutes() === 0);
    const is1HourBeforeExtendedMaintenanceEnds = isTodayExtendedMaintenance && (extendedMaintenanceDay.getUTCHours() === 6 && extendedMaintenanceDay.getUTCMinutes() === 0);
    const extendedMaintenanceEnds = isTodayExtendedMaintenance && (extendedMaintenanceDay.getUTCHours() === 7 && extendedMaintenanceDay.getUTCMinutes() < 1);
    const isPastExtendedMaintenance = isTodayExtendedMaintenance && (extendedMaintenanceDay.getUTCHours() === 7 && extendedMaintenanceDay.getUTCMinutes() >= 1);

    // Create an extended maintenance day time start object and set it to 02:00 JST (17:00 UTC +0)
    const extendedMaintenanceDayTimeStart = new Date(extendedMaintenanceDay);
    extendedMaintenanceDayTimeStart.setUTCHours(17, 0, 0, 0);

    // Create an extended maintenance day time end object and set it to 07:00 JST (22:00 UTC +0)
    const extendedMaintenanceDayTimeEnd = new Date(extendedMaintenanceDay);
    extendedMaintenanceDayTimeEnd.setUTCHours(22, 0, 0, 0);

    /**
     * Set the date one day behind to reflect the Monday before the third Tuesday.
     * These date objects, containing when extended maintenance will begin and end in the US/NY timezone,
     * will be passed to getMessage(). These will NOT be used to compare extended maintenance dates to current date.
     */

    extendedMaintenanceDayTimeStart.setDate(extendedMaintenanceDayTimeEnd.getDate() - 1);
    extendedMaintenanceDayTimeEnd.setDate(extendedMaintenanceDayTimeEnd.getDate() - 1);

    // checking if conditions we set are true. if they are, set the tweetBody, postTweet, and set the flags to true.
    if (is3DaysBeforeExtendedMaintenance) {
        tweetBody = getMessage(
            0,
            extendedMaintenanceDayTimeStart.toLocaleString('en-US', toLocaleDateStringOptions),
            extendedMaintenanceDayTimeStart,
            extendedMaintenanceDayTimeEnd,
        );
        // post tweetBody if postedFlag value is false
        !extendedMaintenancePostedFlags.posted3DayWarning && !isCurrentlyPosting && postTweet(tweetBody);
        extendedMaintenancePostedFlags.posted3DayWarning = true;
    } else if (is1DayBeforeExtendedMaintenance) {
        tweetBody = getMessage(
            1,
            extendedMaintenanceDayTimeStart.toLocaleString('en-US', toLocaleDateStringOptions),
            extendedMaintenanceDayTimeStart,
            extendedMaintenanceDayTimeEnd,
        );
        // post tweetBody if postedFlag value is false
        !extendedMaintenancePostedFlags.posted24HourWarning && !isCurrentlyPosting && postTweet(tweetBody);
        extendedMaintenancePostedFlags.posted24HourWarning = true;
    } else if (is2HoursBeforeExtendedMaintenance) {
        tweetBody = getMessage(
            2,
            extendedMaintenanceDayTimeStart.toLocaleString('en-US', toLocaleDateStringOptions),
            extendedMaintenanceDayTimeStart,
            extendedMaintenanceDayTimeEnd,
        );
        // post tweetBody if postedFlag value is false
        !extendedMaintenancePostedFlags.posted2HourWarning && !isCurrentlyPosting && postTweet(tweetBody);
        extendedMaintenancePostedFlags.posted2HourWarning = true;
    } else if (isExactlyExtendedMaintenance) {
        tweetBody = getMessage(
            3,
            extendedMaintenanceDayTimeStart.toLocaleString('en-US', toLocaleDateStringOptions),
            extendedMaintenanceDayTimeStart,
            extendedMaintenanceDayTimeEnd,
        );
        // post tweetBody if postedFlag value is false
        !extendedMaintenancePostedFlags.postedBeginsWarning && !isCurrentlyPosting && postTweet(tweetBody);
        extendedMaintenancePostedFlags.postedBeginsWarning = true;
    } else if (is1HourBeforeExtendedMaintenanceEnds) {
        tweetBody = getMessage(
            4,
            extendedMaintenanceDayTimeStart.toLocaleString('en-US', toLocaleDateStringOptions),
            extendedMaintenanceDayTimeStart,
            extendedMaintenanceDayTimeEnd,
        );
        // post tweetBody if postedFlag value is false
        !extendedMaintenancePostedFlags.postedEndsIn1HourNotice && !isCurrentlyPosting && postTweet(tweetBody);
        extendedMaintenancePostedFlags.postedEndsIn1HourNotice = true;
    } else if (extendedMaintenanceEnds) {
        tweetBody = getMessage(
            5,
            extendedMaintenanceDayTimeStart.toLocaleString('en-US', toLocaleDateStringOptions),
            extendedMaintenanceDayTimeStart,
            extendedMaintenanceDayTimeEnd,
        );
        // post tweetBody if postedFlag value is false
        !extendedMaintenancePostedFlags.postedEndedNotice && !isCurrentlyPosting && !isPastExtendedMaintenance && postTweet(tweetBody);
        extendedMaintenancePostedFlags.postedEndedNotice = true;
    }

    // console.log('maintenance in US/NY starts:', extendedMaintenanceDayTimeStart.toLocaleString('en-US', toLocaleTimeStringOptionsVerbose));
    // console.log('maintenance in US/NY ends:', extendedMaintenanceDayTimeEnd.toLocaleString('en-US', toLocaleTimeStringOptionsVerbose));

    // console.log('maintenance in JP/TOKYO starts:', extendedMaintenanceDayTimeStart.toLocaleString('en-US', { ...toLocaleTimeStringOptionsVerbose, timeZone: "Asia/Tokyo" }));
    // console.log('maintenance in JP/TOKYO ends:', extendedMaintenanceDayTimeEnd.toLocaleString('en-US', { ...toLocaleTimeStringOptionsVerbose, timeZone: "Asia/Tokyo" }));
    // console.log('\n');

    // check that all flags are true. this will signal that flags are ready to be reset.
    const readyToBeReset = Object.values(extendedMaintenancePostedFlags).every((flagValue) => flagValue === true);

    // reset the flags, making sure to also check that it's past maintenance.
    readyToBeReset && isPastExtendedMaintenance && resetFlags();
}

// eslint-disable-next-line no-unused-vars
const dateCheckingHandler = setInterval(() => extendedMaintenanceObserver(), 15000);