usrspace-browser-addon/src/background.js

import Config from "./config.js";

/**
 * @param {string} url
 * @returns {Promise<any>}
 */
async function fetchJson(url) {
	const response = await fetch(url);
	return response.json();
}

/**
 * @param {number} days
 * @returns {Promise<object>}
 */
function fetchCalendar(days = 28) {
	let url = `${Config.calenderUrl}?o=json`;
	if (days) {
		url += `&r=${days}`;
	}
	return fetchJson(url);
}

/**
 * @returns {Promise<object>}
 */
function fetchSpaceApi() {
	return fetchJson(Config.spaceApiUrl);
}

async function fetchNewData() {
	try {
		const calendarJson = await fetchCalendar();
		window.calendar = calendarJson;
	} catch (error) {
		console.error(error);
	}

	try {
		const spaceApiJson = await fetchSpaceApi();

		await browser.browserAction.setBadgeBackgroundColor({color: Config.openColor});
		await browser.browserAction.setBadgeText({text: spaceApiJson.state.open ? 'open' : ''});

		if (window.spaceApi && window.spaceApi.state.open !== spaceApiJson.state.open) {
			const state = browser.i18n.getMessage(spaceApiJson.state.open ? 'open' : 'closed');
			await browser.notifications.create('status-change', {
				type: 'basic',
				title: browser.i18n.getMessage('stateNotificationTitle'),
				message: browser.i18n.getMessage('stateNotificationMessage', state),
				iconUrl: browser.runtime.getURL('src/icons/favicon.svg')
			});
		}

		window.spaceApi = spaceApiJson;
	} catch (error) {
		console.error(error);
	}
}

let intervalHandler = null;

function stopFetching() {
	if (intervalHandler !== null) {
		clearInterval(intervalHandler);
		intervalHandler = null;
	}
}
function startFetching() {
	fetchNewData();
	if (intervalHandler === null) {
		intervalHandler = setInterval(() => {
			fetchNewData();
		}, Config.refreshTimeout);
	}
}

window.addEventListener('offline', () => {
	stopFetching();
});
window.addEventListener('online', () => {
	startFetching();
});
if (window.navigator.onLine) {
	startFetching();
}