/**
 * Notifications
 */

import { fetchJson, handleError } from './utils/requests';
import { $ } from './utils/dom';
import { delegate } from './utils/events';
import { assertNotNull, assertNotUndefined } from './utils/assert';
import store from './utils/store';

const NOTIFICATION_INTERVAL = 600000,
  NOTIFICATION_EXPIRES = 300000;

function bindSubscriptionLinks() {
  delegate(document, 'fetchcomplete', {
    '.js-subscription-link': event => {
      const target = assertNotNull(event.target.closest('.js-subscription-target'));

      event.detail.text().then(text => {
        target.outerHTML = text;
      });
    },
  });
}

function getNewNotifications() {
  if (document.hidden || !store.hasExpired('notificationCount')) {
    return;
  }

  fetchJson('GET', '/notifications/unread')
    .then(handleError)
    .then(response => response.json())
    .then(({ notifications }) => {
      updateNotificationTicker(notifications);
      storeNotificationCount(notifications);

      setTimeout(getNewNotifications, NOTIFICATION_INTERVAL);
    });
}

function updateNotificationTicker(notificationCount: string | null) {
  const ticker = assertNotNull($<HTMLSpanElement>('.js-notification-ticker'));
  const parsedNotificationCount = Number(notificationCount);

  ticker.dataset.notificationCount = parsedNotificationCount.toString();
  ticker.textContent = parsedNotificationCount.toString();
}

function storeNotificationCount(notificationCount: string) {
  // The current number of notifications are stored along with the time when the data expires
  store.setWithExpireTime('notificationCount', notificationCount, NOTIFICATION_EXPIRES);
}

export function setupNotifications() {
  if (!window.booru.userIsSignedIn) return;

  // Fetch notifications from the server at a regular interval
  setTimeout(getNewNotifications, NOTIFICATION_INTERVAL);

  // Update the current number of notifications based on the latest page load
  const ticker = assertNotNull($<HTMLSpanElement>('.js-notification-ticker'));
  storeNotificationCount(assertNotUndefined(ticker.dataset.notificationCount));

  // Update ticker when the stored value changes - this will occur in all open tabs
  store.watch('notificationCount', updateNotificationTicker);

  bindSubscriptionLinks();
}