Rocket.Chat/app/e2e/client/tabbar.js

import { Meteor } from 'meteor/meteor';
import { Session } from 'meteor/session';
import { Tracker } from 'meteor/tracker';

import { hasAllPermission } from '../../authorization';
import { call, TabBar } from '../../ui-utils';
import { ChatRoom } from '../../models';
import { settings } from '../../settings';

Meteor.startup(() => {
	Tracker.autorun(() => {
		if (settings.get('E2E_Enable')) {
			TabBar.addButton({
				groups: ['direct', 'group'],
				id: 'e2e',
				i18nTitle: 'E2E',
				icon: 'key',
				class: () => (ChatRoom.findOne(Session.get('openedRoom')) || {}).encrypted && 'enabled',
				action: () => {
					const room = ChatRoom.findOne(Session.get('openedRoom'));
					call('saveRoomSettings', room._id, 'encrypted', !room.encrypted);
				},
				order: 13,
				condition: () => hasAllPermission('edit-room', Session.get('openedRoom')),
			});
		} else {
			TabBar.removeButton('e2e');
		}
	});
});