import { callApi } from '../api/gramjs';
import { DEBUG } from '../config';
import { getDispatch, getGlobal } from '../lib/teact/teactn';
import { IS_SERVICE_WORKER_SUPPORTED } from './environment';

function getDeviceToken(subscription: PushSubscription) {
  const data = subscription.toJSON();
  return JSON.stringify({ endpoint: data.endpoint, keys: data.keys });
}

function checkIfSupported() {
  if (!IS_SERVICE_WORKER_SUPPORTED) return false;
  if (!('showNotification' in ServiceWorkerRegistration.prototype)) {
    if (DEBUG) {
      // eslint-disable-next-line no-console
      console.log('[PUSH] Push notifications aren\'t supported.');
    }
    return false;
  }

  // Check the current Notification permission.
  // If its denied, it's a permanent block until the
  // user changes the permission
  if (Notification.permission === 'denied') {
    if (DEBUG) {
      // eslint-disable-next-line no-console
      console.log('[PUSH] The user has blocked push notifications.');
    }
    return false;
  }

  // Check if push messaging is supported
  if (!('PushManager' in window)) {
    if (DEBUG) {
      // eslint-disable-next-line no-console
      console.log('[PUSH] Push messaging isn\'t supported.');
    }
    return false;
  }
  return true;
}

const expirationTime = 12 * 60 * 60 * 1000; // 12 hours

function checkIfShouldResubscribe(subscription: PushSubscription | null) {
  const global = getGlobal();
  if (!global.push || !subscription) return true;
  if (getDeviceToken(subscription) !== global.push.deviceToken) return true;
  return Date.now() - global.push.subscribedAt > expirationTime;
}

async function unsubscribe(subscription: PushSubscription | null) {
  const global = getGlobal();
  const dispatch = getDispatch();
  if (subscription) {
    try {
      const deviceToken = getDeviceToken(subscription);
      await callApi('unregisterDevice', deviceToken);
      await subscription.unsubscribe();
      dispatch.deleteDeviceToken();
      return;
    } catch (error) {
      if (DEBUG) {
        // eslint-disable-next-line no-console
        console.log('[PUSH] Unable to unsubscribe from push.', error);
      }
    }
  }
  if (global.push) {
    await callApi('unregisterDevice', global.push.deviceToken);
    dispatch.deleteDeviceToken();
  }
}

export async function unsubscribeFromPush() {
  if (!checkIfSupported()) return;
  const serviceWorkerRegistration = await navigator.serviceWorker.ready;
  const subscription = await serviceWorkerRegistration.pushManager.getSubscription();
  await unsubscribe(subscription);
}

export async function subscribeToPush() {
  if (!checkIfSupported()) return;
  const serviceWorkerRegistration = await navigator.serviceWorker.ready;
  let subscription = await serviceWorkerRegistration.pushManager.getSubscription();
  if (!checkIfShouldResubscribe(subscription)) return;
  await unsubscribe(subscription);
  try {
    subscription = await serviceWorkerRegistration.pushManager.subscribe({
      userVisibleOnly: true,
    });
    const deviceToken = getDeviceToken(subscription);
    if (DEBUG) {
      // eslint-disable-next-line no-console
      console.log('[PUSH] Received push subscription: ', deviceToken);
    }
    await callApi('registerDevice', deviceToken);
    getDispatch().setDeviceToken(deviceToken);
  } catch (error) {
    if (Notification.permission === 'denied' as NotificationPermission) {
      // The user denied the notification permission which
      // means we failed to subscribe and the user will need
      // to manually change the notification permission to
      // subscribe to push messages
      if (DEBUG) {
        // eslint-disable-next-line no-console
        console.log('[PUSH] Permission for Notifications was denied');
      }
    } else if (DEBUG) {
      // A problem occurred with the subscription, this can
      // often be down to an issue or lack of the gcm_sender_id
      // and / or gcm_user_visible_only
      // eslint-disable-next-line no-console
      console.log('[PUSH] Unable to subscribe to push.', error);
    }
  }
}

// Notify service worker that client is fully loaded
export function notifyClientReady() {
  if (!navigator.serviceWorker.controller) return;
  navigator.serviceWorker.controller.postMessage({
    type: 'clientReady',
  });
}