/**
 * Main Javascript file
 *
 * @author Giancarlo Voci
 * @date 27/06/2018
 * @time 17:42
 */

import $ from '../../shared/jquery.js';
import './common';
import { AjaxReq } from './OMGUtils';

const CUSTOM_NOTIFICATION_CODE = 0x4000;
const FOCUS_INTERVAL_MS = 1000;
const NOTIFICATION_REFRESH_INTERVAL_MS = 3000;
const DELETE_ALL_NOTIFICATION_LINK = '#';

/**
 * Adds a notification item to the notification menu.
 *
 * @param {{caption: string, code: number, count: number, link: string|null, timestamp: string}} notification Notification data.
 * @returns {JQuery} Notification menu item.
 * @sideEffects Registers a click handler.
 */
function createNotificationItem(notification) {
	return $('<a>', { class: 'dropdown-item', href: '#' })
		.text(`[${notification.timestamp}] ${notification.caption}`)
		.append($('<span>', { class: 'ms-1 badge bg-danger', text: notification.count }))
		.on('click', event => {
			event.preventDefault();
			deleteNotification(notification.link, notification.code);
		});
}

/**
 * Renders the notifications visible to the user.
 *
 * @param {Array<object>} notifications Notifications returned by the API.
 * @returns {void}
 * @sideEffects Updates the notification menu.
 */
function renderNotifications(notifications) {
	const visibleNotifications = notifications.filter(
		notification => notification.code <= CUSTOM_NOTIFICATION_CODE,
	);
	const notificationArea = $('#notification_area').empty();

	if (visibleNotifications.length === 0) {
		$('#notification_area_button').addClass('disabled');
		$('#sysmsgnum').empty();
		return;
	}

	visibleNotifications.forEach(notification => notificationArea.append(createNotificationItem(notification)));
	notificationArea.append(
		$('<a>', { id: 'notification_area_deleteall', class: 'dropdown-item text-center', href: '#', text: 'Cancella tutto' })
			.on('click', event => {
				event.preventDefault();
				deleteNotification(DELETE_ALL_NOTIFICATION_LINK, 0);
			}),
	);
	$('#notification_area_button').removeClass('disabled');
	$('#sysmsgnum').text(visibleNotifications.length);
}

/**
 * Retrieves and renders the current system notifications.
 *
 * @returns {void}
 * @sideEffects Performs a network request and updates the notification menu.
 */
function refreshNotificationArea() {
	AjaxReq(`${BASEURL}/api.system.getserverstatus`, { method: 'GET' }).fetchPromise()
		.then(data => renderNotifications(data.notify))
		.catch(error => console.error('Unable to refresh system notifications.', error));
}

/**
 * Deletes one notification and optionally follows its link.
 *
 * @param {string|null} link Link associated with the notification.
 * @param {number} code Notification code.
 * @returns {void}
 * @sideEffects Performs a network request and may navigate the browser.
 */
function deleteNotification(link, code) {
	fetch(`${BASEURL}/api.system.removenotification/${code}`, { method: 'POST' })
		.then(response => {
			if (!response.ok) {
				return Promise.reject(response);
			}

			if (link && link !== DELETE_ALL_NOTIFICATION_LINK) {
				window.location.href = `${BASEURL}${link}`;
			}
		})
		.catch(error => {
			console.error('Unable to delete the notification.', { code, error });
			alert('NotificationDelete error');
		});
}

/**
 * Enables confirmation prompts for elements that require explicit user approval.
 *
 * @returns {void}
 * @sideEffects Registers click handlers.
 */
function setupConfirmationDialog() {
	$('.requestconfirm').on('click', function (event) {
		if (!confirm($(this).data('confirmtext'))) {
			event.preventDefault();
		}
	});
}

/**
 * Keeps elements marked with forcefocus focused.
 *
 * @returns {void}
 * @sideEffects Starts an interval timer.
 */
function startFocusEnforcement() {
	setInterval(() => $('[forcefocus]').focus(), FOCUS_INTERVAL_MS);
}

/**
 * Initializes frontend interactions after the document is ready.
 *
 * @returns {void}
 * @sideEffects Registers UI handlers and starts polling timers.
 */
function initializeFrontend() {
	setupConfirmationDialog();
	refreshNotificationArea();
	startFocusEnforcement();

	$('body').on('submit', 'form', function () {
		$('body').focus();
		$('form input,form select').prop('readonly', true);
		this.submit();
		return false;
	});

	setInterval(refreshNotificationArea, NOTIFICATION_REFRESH_INTERVAL_MS);
	window.NotificationDelete = deleteNotification;
}

document.addEventListener('DOMContentLoaded', initializeFrontend);