Sends countdown notifications via Pushover (usage example: `./pushover-countdown.js ./z-events.json`).

pushover-countdown.js

#!/usr/bin/env node

const https = require("https");
const config = require(process.argv[2]);

function durationString(target) {

    const msPerMinute = 60 * 1000;
    const msPerHour = msPerMinute * 60;
    const msPerDay = msPerHour * 24;
    const msPerWeek = msPerDay * 7;
    const msPerMonth = msPerDay * 31;
    const msPerYear = msPerDay * 365;

    const duration = target - (new Date()).getTime();

    if (duration < 0) {
        return null;
    } else if (duration < msPerWeek) {
        const days = Math.ceil(duration / msPerDay);
        return `${days} day${days > 1 ? "s" : ""}`;   
    } else if (duration < 2 * msPerMonth) {
        const weeks = Math.floor(duration / msPerWeek);
        const days = Math.ceil((duration % msPerWeek) / msPerDay);
        return `${weeks} week${weeks > 1 ? "s" : ""} ${days} day${days > 1 ? "s" : ""}`;   
    } else {
        const months = Math.floor(duration / msPerMonth);
        const days = Math.ceil((duration % msPerMonth) / msPerDay);
        return `${months} month${months > 1 ? "s" : ""} ${days} day${days > 1 ? "s" : ""}`;
    }

}

function notification(token, user, title, message) {

    const req = https.request({
        "method": "POST",
        "hostname": "api.pushover.net",
        "path": "/1/messages.json",
        "headers": {
            "Content-Type": "application/json",
        },
    }, function (res) {
        res.on("error", function (error) {
            console.error(error);
        });
    });

    req.write(JSON.stringify({
        "token": token,
        "user": user,
        "title": title,
        "message": message,
    }));

    req.end();

}

for (const [name, date] of Object.entries(config.events)) {
    const msg = durationString(new Date(date).getTime());
    if (msg) {
        notification(config.token, config.user, name, msg);
    }
}

z-events.json

{
    "token": "******************************",
    "user": "******************************",
    "events": {
        "Christmas": "2022-12-25",
        "New Year's": "2023-01-01"
    }
}