Rocket.Chat/client/components/connectionStatus/ConnectionStatusAlert.js

import { Icon } from '@rocket.chat/fuselage';
import React, { useEffect, useRef, useState } from 'react';

import { useConnectionStatus } from '../../contexts/ConnectionStatusContext';
import { useTranslation } from '../../contexts/TranslationContext';
import './ConnectionStatusAlert.css';

const getReconnectCountdown = (retryTime) => {
	const timeDiff = retryTime - Date.now();
	return (timeDiff > 0 && Math.round(timeDiff / 1000)) || 0;
};

const useReconnectCountdown = (retryTime, status) => {
	const reconnectionTimerRef = useRef();
	const [reconnectCountdown, setReconnectCountdown] = useState(() => getReconnectCountdown(retryTime));

	useEffect(() => {
		if (status === 'waiting') {
			if (reconnectionTimerRef.current) {
				return;
			}

			reconnectionTimerRef.current = setInterval(() => {
				setReconnectCountdown(getReconnectCountdown(retryTime));
			}, 500);
			return;
		}

		clearInterval(reconnectionTimerRef.current);
		reconnectionTimerRef.current = null;
	}, [retryTime, status]);

	useEffect(() => () => {
		clearInterval(reconnectionTimerRef.current);
	}, []);

	return reconnectCountdown;
};

function ConnectionStatusAlert() {
	const { connected, retryTime, status, reconnect } = useConnectionStatus();
	const reconnectCountdown = useReconnectCountdown(retryTime, status);
	const t = useTranslation();

	if (connected) {
		return null;
	}

	const handleRetryClick = (event) => {
		event.preventDefault();
		reconnect && reconnect();
	};

	return <div className='ConnectionStatusAlert' role='alert'>
		<strong>
			<Icon name='warning' /> {t('meteor_status', { context: status })}
		</strong>

		{status === 'waiting' && <>
			{' '}
			{t('meteor_status_reconnect_in', { count: reconnectCountdown })}
		</>}

		{['waiting', 'offline'].includes(status) && <>
			{' '}
			<a className='ConnectionStatusAlert__retry-link' href='#' onClick={handleRetryClick}>
				{t('meteor_status_try_now', { context: status })}
			</a>
		</>}
	</div>;
}

export default ConnectionStatusAlert;