Web Push Notifications (#3243)

* feat: Register push subscription

* feat: Notify when mentioned

* feat: Boost, favourite, reply, follow, follow request

* feat: Notification interaction

* feat: Handle change of public key

* feat: Unsubscribe if things go wrong

* feat: Do not send normal notifications if push is enabled

* feat: Focus client if open

* refactor: Move push logic to WebPushSubscription

* feat: Better title and body

* feat: Localize messages

* chore: Fix lint errors

* feat: Settings

* refactor: Lazy load

* fix: Check if push settings exist

* feat: Device-based preferences

* refactor: Simplify logic

* refactor: Pull request feedback

* refactor: Pull request feedback

* refactor: Create /api/web/push_subscriptions endpoint

* feat: Spec PushSubscriptionController

* refactor: WebPushSubscription => Web::PushSubscription

* feat: Spec Web::PushSubscription

* feat: Display first media attachment

* feat: Support direction

* fix: Stuff broken while rebasing

* refactor: Integration with session activations

* refactor: Cleanup

* refactor: Simplify implementation

* feat: Set VAPID keys via environment

* chore: Comments

* fix: Crash when no alerts

* fix: Set VAPID keys in testing environment

* fix: Follow link

* feat: Notification actions

* fix: Delete previous subscription

* chore: Temporary logs

* refactor: Move migration to a later date

* fix: Fetch the correct session activation and misc bugs

* refactor: Move migration to a later date

* fix: Remove follow request (no notifications)

* feat: Send administrator contact to push service

* feat: Set time-to-live

* fix: Do not show sensitive images

* fix: Reducer crash in error handling

* feat: Add badge

* chore: Fix lint error

* fix: Checkbox label overlap

* fix: Check for payload support

* fix: Rename action "type" (crash in latest Chrome)

* feat: Action to expand notification

* fix: Lint errors

* fix: Unescape notification body

* fix: Do not allow boosting if the status is hidden

* feat: Add VAPID keys to the production sample environment

* fix: Strip HTML tags from status

* refactor: Better error messages

* refactor: Handle browser not implementing the VAPID protocol (Samsung Internet)

* fix: Error when target_status is nil

* fix: Handle lack of image

* fix: Delete reference to invalid subscriptions

* feat: Better error handling

* fix: Unescape HTML characters after tags are striped

* refactor: Simpify code

* fix: Modify to work with #4091

* Sort strings alphabetically

* i18n: Updated Polish translation

it annoys me that it's not fully localized :P

* refactor: Use current_session in PushSubscriptionController

* fix: Rebase mistake

* fix: Set cacheName to mastodon

* refactor: Pull request feedback

* refactor: Remove logging statements

* chore(yarn): Fix conflicts with master

* chore(yarn): Copy latest from master

* chore(yarn): Readd offline-plugin

* refactor: Use save! and update!

* refactor: Send notifications async

* fix: Allow retry when push fails

* fix: Save track for failed pushes

* fix: Minify sw.js

* fix: Remove account_id from fabricator

22 files changed, 630 insertions, 10 deletions

diff --git a/app/controllers/api/web/push_subscriptions_controller.rb b/app/controllers/api/web/push_subscriptions_controller.rb
new file mode 100644
index 000000000..8425db7b4
--- /dev/null
+++ b/app/controllers/api/web/push_subscriptions_controller.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+class Api::Web::PushSubscriptionsController < Api::BaseController
+  respond_to :json
+
+  before_action :require_user!
+
+  def create
+    params.require(:data).require(:endpoint)
+    params.require(:data).require(:keys).require([:auth, :p256dh])
+
+    active_session = current_session
+
+    unless active_session.web_push_subscription.nil?
+      active_session.web_push_subscription.destroy!
+      active_session.update!(web_push_subscription: nil)
+    end
+
+    web_subscription = ::Web::PushSubscription.create!(
+      endpoint: params[:data][:endpoint],
+      key_p256dh: params[:data][:keys][:p256dh],
+      key_auth: params[:data][:keys][:auth]
+    )
+
+    active_session.update!(web_push_subscription: web_subscription)
+
+    render json: web_subscription.as_payload
+  end
+
+  def update
+    params.require([:id, :data])
+
+    web_subscription = ::Web::PushSubscription.find(params[:id])
+
+    web_subscription.update!(data: params[:data])
+
+    render json: web_subscription.as_payload
+  end
+end
diff --git a/app/controllers/home_controller.rb b/app/controllers/home_controller.rb
index 8a8b9ec76..1585bc810 100644
--- a/app/controllers/home_controller.rb
+++ b/app/controllers/home_controller.rb
@@ -22,6 +22,7 @@ class HomeController < ApplicationController
   def initial_state_params
     {
       settings: Web::Setting.find_by(user: current_user)&.data || {},
+      push_subscription: current_account.user.web_push_subscription(current_session),
       current_account: current_account,
       token: current_session.token,
       admin: Account.find_local(Setting.site_contact_username),
diff --git a/app/javascript/mastodon/actions/push_notifications.js b/app/javascript/mastodon/actions/push_notifications.js
new file mode 100644
index 000000000..55661d2b0
--- /dev/null
+++ b/app/javascript/mastodon/actions/push_notifications.js
@@ -0,0 +1,52 @@
+import axios from 'axios';
+
+export const SET_BROWSER_SUPPORT = 'PUSH_NOTIFICATIONS_SET_BROWSER_SUPPORT';
+export const SET_SUBSCRIPTION = 'PUSH_NOTIFICATIONS_SET_SUBSCRIPTION';
+export const CLEAR_SUBSCRIPTION = 'PUSH_NOTIFICATIONS_CLEAR_SUBSCRIPTION';
+export const ALERTS_CHANGE = 'PUSH_NOTIFICATIONS_ALERTS_CHANGE';
+
+export function setBrowserSupport (value) {
+  return {
+    type: SET_BROWSER_SUPPORT,
+    value,
+  };
+}
+
+export function setSubscription (subscription) {
+  return {
+    type: SET_SUBSCRIPTION,
+    subscription,
+  };
+}
+
+export function clearSubscription () {
+  return {
+    type: CLEAR_SUBSCRIPTION,
+  };
+}
+
+export function changeAlerts(key, value) {
+  return dispatch => {
+    dispatch({
+      type: ALERTS_CHANGE,
+      key,
+      value,
+    });
+
+    dispatch(saveSettings());
+  };
+}
+
+export function saveSettings() {
+  return (_, getState) => {
+    const state = getState().get('push_notifications');
+    const subscription = state.get('subscription');
+    const alerts = state.get('alerts');
+
+    axios.put(`/api/web/push_subscriptions/${subscription.get('id')}`, {
+      data: {
+        alerts,
+      },
+    });
+  };
+}
diff --git a/app/javascript/mastodon/features/notifications/components/column_settings.js b/app/javascript/mastodon/features/notifications/components/column_settings.js
index 260594894..31cac5bc7 100644
--- a/app/javascript/mastodon/features/notifications/components/column_settings.js
+++ b/app/javascript/mastodon/features/notifications/components/column_settings.js
@@ -9,18 +9,27 @@ export default class ColumnSettings extends React.PureComponent {
 
   static propTypes = {
     settings: ImmutablePropTypes.map.isRequired,
+    pushSettings: ImmutablePropTypes.map.isRequired,
     onChange: PropTypes.func.isRequired,
     onSave: PropTypes.func.isRequired,
     onClear: PropTypes.func.isRequired,
   };
 
+  onPushChange = (key, checked) => {
+    this.props.onChange(['push', ...key], checked);
+  }
+
   render () {
-    const { settings, onChange, onClear } = this.props;
+    const { settings, pushSettings, onChange, onClear } = this.props;
 
     const alertStr = <FormattedMessage id='notifications.column_settings.alert' defaultMessage='Desktop notifications' />;
     const showStr  = <FormattedMessage id='notifications.column_settings.show' defaultMessage='Show in column' />;
     const soundStr = <FormattedMessage id='notifications.column_settings.sound' defaultMessage='Play sound' />;
 
+    const showPushSettings = pushSettings.get('browserSupport') && pushSettings.get('isSubscribed');
+    const pushStr = showPushSettings && <FormattedMessage id='notifications.column_settings.push' defaultMessage='Push notifications' />;
+    const pushMeta = showPushSettings && <FormattedMessage id='notifications.column_settings.push_meta' defaultMessage='This device' />;
+
     return (
       <div>
         <div className='column-settings__row'>
@@ -30,7 +39,8 @@ export default class ColumnSettings extends React.PureComponent {
         <span className='column-settings__section'><FormattedMessage id='notifications.column_settings.follow' defaultMessage='New followers:' /></span>
 
         <div className='column-settings__row'>
-          <SettingToggle prefix='notifications' settings={settings} settingKey={['alerts', 'follow']} onChange={onChange} label={alertStr} />
+          <SettingToggle prefix='notifications_desktop' settings={settings} settingKey={['alerts', 'follow']} onChange={onChange} label={alertStr} />
+          {showPushSettings && <SettingToggle prefix='notifications_push' settings={pushSettings} settingKey={['alerts', 'follow']} meta={pushMeta} onChange={this.onPushChange} label={pushStr} />}
           <SettingToggle prefix='notifications' settings={settings} settingKey={['shows', 'follow']} onChange={onChange} label={showStr} />
           <SettingToggle prefix='notifications' settings={settings} settingKey={['sounds', 'follow']} onChange={onChange} label={soundStr} />
         </div>
@@ -38,7 +48,8 @@ export default class ColumnSettings extends React.PureComponent {
         <span className='column-settings__section'><FormattedMessage id='notifications.column_settings.favourite' defaultMessage='Favourites:' /></span>
 
         <div className='column-settings__row'>
-          <SettingToggle prefix='notifications' settings={settings} settingKey={['alerts', 'favourite']} onChange={onChange} label={alertStr} />
+          <SettingToggle prefix='notifications_desktop' settings={settings} settingKey={['alerts', 'favourite']} onChange={onChange} label={alertStr} />
+          {showPushSettings && <SettingToggle prefix='notifications_push' settings={pushSettings} settingKey={['alerts', 'favourite']} meta={pushMeta} onChange={this.onPushChange} label={pushStr} />}
           <SettingToggle prefix='notifications' settings={settings} settingKey={['shows', 'favourite']} onChange={onChange} label={showStr} />
           <SettingToggle prefix='notifications' settings={settings} settingKey={['sounds', 'favourite']} onChange={onChange} label={soundStr} />
         </div>
@@ -46,7 +57,8 @@ export default class ColumnSettings extends React.PureComponent {
         <span className='column-settings__section'><FormattedMessage id='notifications.column_settings.mention' defaultMessage='Mentions:' /></span>
 
         <div className='column-settings__row'>
-          <SettingToggle prefix='notifications' settings={settings} settingKey={['alerts', 'mention']} onChange={onChange} label={alertStr} />
+          <SettingToggle prefix='notifications_desktop' settings={settings} settingKey={['alerts', 'mention']} onChange={onChange} label={alertStr} />
+          {showPushSettings && <SettingToggle prefix='notifications_push' settings={pushSettings} settingKey={['alerts', 'mention']} meta={pushMeta} onChange={this.onPushChange} label={pushStr} />}
           <SettingToggle prefix='notifications' settings={settings} settingKey={['shows', 'mention']} onChange={onChange} label={showStr} />
           <SettingToggle prefix='notifications' settings={settings} settingKey={['sounds', 'mention']} onChange={onChange} label={soundStr} />
         </div>
@@ -54,7 +66,8 @@ export default class ColumnSettings extends React.PureComponent {
         <span className='column-settings__section'><FormattedMessage id='notifications.column_settings.reblog' defaultMessage='Boosts:' /></span>
 
         <div className='column-settings__row'>
-          <SettingToggle prefix='notifications' settings={settings} settingKey={['alerts', 'reblog']} onChange={onChange} label={alertStr} />
+          <SettingToggle prefix='notifications_desktop' settings={settings} settingKey={['alerts', 'reblog']} onChange={onChange} label={alertStr} />
+          {showPushSettings && <SettingToggle prefix='notifications_push' settings={pushSettings} settingKey={['alerts', 'reblog']} meta={pushMeta} onChange={this.onPushChange} label={pushStr} />}
           <SettingToggle prefix='notifications' settings={settings} settingKey={['shows', 'reblog']} onChange={onChange} label={showStr} />
           <SettingToggle prefix='notifications' settings={settings} settingKey={['sounds', 'reblog']} onChange={onChange} label={soundStr} />
         </div>
diff --git a/app/javascript/mastodon/features/notifications/components/setting_toggle.js b/app/javascript/mastodon/features/notifications/components/setting_toggle.js
index 510820358..be1ff91d6 100644
--- a/app/javascript/mastodon/features/notifications/components/setting_toggle.js
+++ b/app/javascript/mastodon/features/notifications/components/setting_toggle.js
@@ -10,6 +10,7 @@ export default class SettingToggle extends React.PureComponent {
     settings: ImmutablePropTypes.map.isRequired,
     settingKey: PropTypes.array.isRequired,
     label: PropTypes.node.isRequired,
+    meta: PropTypes.node,
     onChange: PropTypes.func.isRequired,
   }
 
@@ -18,13 +19,14 @@ export default class SettingToggle extends React.PureComponent {
   }
 
   render () {
-    const { prefix, settings, settingKey, label } = this.props;
+    const { prefix, settings, settingKey, label, meta } = this.props;
     const id = ['setting-toggle', prefix, ...settingKey].filter(Boolean).join('-');
 
     return (
       <div className='setting-toggle'>
         <Toggle id={id} checked={settings.getIn(settingKey)} onChange={this.onChange} />
         <label htmlFor={id} className='setting-toggle__label'>{label}</label>
+        {meta && <span className='setting-meta__label'>{meta}</span>}
       </div>
     );
   }
diff --git a/app/javascript/mastodon/features/notifications/containers/column_settings_container.js b/app/javascript/mastodon/features/notifications/containers/column_settings_container.js
index b139d4615..d4ead7881 100644
--- a/app/javascript/mastodon/features/notifications/containers/column_settings_container.js
+++ b/app/javascript/mastodon/features/notifications/containers/column_settings_container.js
@@ -3,6 +3,7 @@ import { defineMessages, injectIntl } from 'react-intl';
 import ColumnSettings from '../components/column_settings';
 import { changeSetting, saveSettings } from '../../../actions/settings';
 import { clearNotifications } from '../../../actions/notifications';
+import { changeAlerts as changePushNotifications, saveSettings as savePushNotificationSettings } from '../../../actions/push_notifications';
 import { openModal } from '../../../actions/modal';
 
 const messages = defineMessages({
@@ -12,16 +13,22 @@ const messages = defineMessages({
 
 const mapStateToProps = state => ({
   settings: state.getIn(['settings', 'notifications']),
+  pushSettings: state.get('push_notifications'),
 });
 
 const mapDispatchToProps = (dispatch, { intl }) => ({
 
   onChange (key, checked) {
-    dispatch(changeSetting(['notifications', ...key], checked));
+    if (key[0] === 'push') {
+      dispatch(changePushNotifications(key.slice(1), checked));
+    } else {
+      dispatch(changeSetting(['notifications', ...key], checked));
+    }
   },
 
   onSave () {
     dispatch(saveSettings());
+    dispatch(savePushNotificationSettings());
   },
 
   onClear () {
diff --git a/app/javascript/mastodon/main.js b/app/javascript/mastodon/main.js
index d7ffa8ea6..d2c9d1c94 100644
--- a/app/javascript/mastodon/main.js
+++ b/app/javascript/mastodon/main.js
@@ -29,6 +29,14 @@ function main() {
     const props = JSON.parse(mountNode.getAttribute('data-props'));
 
     ReactDOM.render(<Mastodon {...props} />, mountNode);
+    if (process.env.NODE_ENV === 'production') {
+      // avoid offline in dev mode because it's harder to debug
+      const OfflinePluginRuntime = require('offline-plugin/runtime');
+      const WebPushSubscription = require('./web_push_subscription');
+
+      OfflinePluginRuntime.install();
+      WebPushSubscription.register();
+    }
     perf.stop('main()');
   });
 }
diff --git a/app/javascript/mastodon/reducers/index.js b/app/javascript/mastodon/reducers/index.js
index 919345f16..3aaf259c2 100644
--- a/app/javascript/mastodon/reducers/index.js
+++ b/app/javascript/mastodon/reducers/index.js
@@ -10,6 +10,7 @@ import accounts_counters from './accounts_counters';
 import statuses from './statuses';
 import relationships from './relationships';
 import settings from './settings';
+import push_notifications from './push_notifications';
 import status_lists from './status_lists';
 import cards from './cards';
 import reports from './reports';
@@ -32,6 +33,7 @@ const reducers = {
   statuses,
   relationships,
   settings,
+  push_notifications,
   cards,
   reports,
   contexts,
diff --git a/app/javascript/mastodon/reducers/push_notifications.js b/app/javascript/mastodon/reducers/push_notifications.js
new file mode 100644
index 000000000..31a40d246
--- /dev/null
+++ b/app/javascript/mastodon/reducers/push_notifications.js
@@ -0,0 +1,51 @@
+import { STORE_HYDRATE } from '../actions/store';
+import { SET_BROWSER_SUPPORT, SET_SUBSCRIPTION, CLEAR_SUBSCRIPTION, ALERTS_CHANGE } from '../actions/push_notifications';
+import Immutable from 'immutable';
+
+const initialState = Immutable.Map({
+  subscription: null,
+  alerts: new Immutable.Map({
+    follow: false,
+    favourite: false,
+    reblog: false,
+    mention: false,
+  }),
+  isSubscribed: false,
+  browserSupport: false,
+});
+
+export default function push_subscriptions(state = initialState, action) {
+  switch(action.type) {
+  case STORE_HYDRATE: {
+    const push_subscription = action.state.get('push_subscription');
+
+    if (push_subscription) {
+      return state
+        .set('subscription', new Immutable.Map({
+          id: push_subscription.get('id'),
+          endpoint: push_subscription.get('endpoint'),
+        }))
+        .set('alerts', push_subscription.get('alerts') || initialState.get('alerts'))
+        .set('isSubscribed', true);
+    }
+
+    return state;
+  }
+  case SET_SUBSCRIPTION:
+    return state
+      .set('subscription', new Immutable.Map({
+        id: action.subscription.id,
+        endpoint: action.subscription.endpoint,
+      }))
+      .set('alerts', new Immutable.Map(action.subscription.alerts))
+      .set('isSubscribed', true);
+  case SET_BROWSER_SUPPORT:
+    return state.set('browserSupport', action.value);
+  case CLEAR_SUBSCRIPTION:
+    return initialState;
+  case ALERTS_CHANGE:
+    return state.setIn(action.key, action.value);
+  default:
+    return state;
+  }
+};
diff --git a/app/javascript/mastodon/service_worker/entry.js b/app/javascript/mastodon/service_worker/entry.js
new file mode 100644
index 000000000..364b67066
--- /dev/null
+++ b/app/javascript/mastodon/service_worker/entry.js
@@ -0,0 +1 @@
+import './web_push_notifications';
diff --git a/app/javascript/mastodon/service_worker/web_push_notifications.js b/app/javascript/mastodon/service_worker/web_push_notifications.js
new file mode 100644
index 000000000..1708aa9f7
--- /dev/null
+++ b/app/javascript/mastodon/service_worker/web_push_notifications.js
@@ -0,0 +1,86 @@
+const handlePush = (event) => {
+  const options = event.data.json();
+
+  options.body = options.data.nsfw || options.data.content;
+  options.image = options.image || undefined; // Null results in a network request (404)
+  options.timestamp = options.timestamp && new Date(options.timestamp);
+
+  const expandAction = options.data.actions.find(action => action.todo === 'expand');
+
+  if (expandAction) {
+    options.actions = [expandAction];
+    options.hiddenActions = options.data.actions.filter(action => action !== expandAction);
+
+    options.data.hiddenImage = options.image;
+    options.image = undefined;
+  } else {
+    options.actions = options.data.actions;
+  }
+
+  event.waitUntil(self.registration.showNotification(options.title, options));
+};
+
+const cloneNotification = (notification) => {
+  const clone = {  };
+
+  for(var k in notification) {
+    clone[k] = notification[k];
+  }
+
+  return clone;
+};
+
+const expandNotification = (notification) => {
+  const nextNotification = cloneNotification(notification);
+
+  nextNotification.body = notification.data.content;
+  nextNotification.image = notification.data.hiddenImage;
+  nextNotification.actions = notification.data.actions.filter(action => action.todo !== 'expand');
+
+  return self.registration.showNotification(nextNotification.title, nextNotification);
+};
+
+const makeRequest = (notification, action) =>
+  fetch(action.action, {
+    headers: {
+      'Authorization': `Bearer ${notification.data.access_token}`,
+      'Content-Type': 'application/json',
+    },
+    method: action.method,
+    credentials: 'include',
+  });
+
+const removeActionFromNotification = (notification, action) => {
+  const actions = notification.actions.filter(act => act.action !== action.action);
+
+  const nextNotification = cloneNotification(notification);
+
+  nextNotification.actions = actions;
+
+  return self.registration.showNotification(nextNotification.title, nextNotification);
+};
+
+const handleNotificationClick = (event) => {
+  const reactToNotificationClick = new Promise((resolve, reject) => {
+    if (event.action) {
+      const action = event.notification.data.actions.find(({ action }) => action === event.action);
+
+      if (action.todo === 'expand') {
+        resolve(expandNotification(event.notification));
+      } else if (action.todo === 'request') {
+        resolve(makeRequest(event.notification, action)
+          .then(() => removeActionFromNotification(event.notification, action)));
+      } else {
+        reject(`Unknown action: ${action.todo}`);
+      }
+    } else {
+      event.notification.close();
+      resolve(self.clients.openWindow(event.notification.data.url));
+    }
+  });
+
+  event.waitUntil(reactToNotificationClick);
+};
+
+self.addEventListener('push', handlePush);
+self.addEventListener('notificationclick', handleNotificationClick);
diff --git a/app/javascript/mastodon/web_push_subscription.js b/app/javascript/mastodon/web_push_subscription.js
new file mode 100644
index 000000000..391d3bcec
--- /dev/null
+++ b/app/javascript/mastodon/web_push_subscription.js
@@ -0,0 +1,109 @@
+import axios from 'axios';
+import { store } from './containers/mastodon';
+import { setBrowserSupport, setSubscription, clearSubscription } from './actions/push_notifications';
+
+// Taken from https://www.npmjs.com/package/web-push
+const urlBase64ToUint8Array = (base64String) => {
+  const padding = '='.repeat((4 - base64String.length % 4) % 4);
+  const base64 = (base64String + padding)
+    .replace(/\-/g, '+')
+    .replace(/_/g, '/');
+
+  const rawData = window.atob(base64);
+  const outputArray = new Uint8Array(rawData.length);
+
+  for (let i = 0; i < rawData.length; ++i) {
+    outputArray[i] = rawData.charCodeAt(i);
+  }
+  return outputArray;
+};
+
+const getApplicationServerKey = () => document.querySelector('[name="applicationServerKey"]').getAttribute('content');
+
+const getRegistration = () => navigator.serviceWorker.ready;
+
+const getPushSubscription = (registration) =>
+  registration.pushManager.getSubscription()
+    .then(subscription => ({ registration, subscription }));
+
+const subscribe = (registration) =>
+  registration.pushManager.subscribe({
+    userVisibleOnly: true,
+    applicationServerKey: urlBase64ToUint8Array(getApplicationServerKey()),
+  });
+
+const unsubscribe = ({ registration, subscription }) =>
+  subscription ? subscription.unsubscribe().then(() => registration) : registration;
+
+const sendSubscriptionToBackend = (subscription) =>
+  axios.post('/api/web/push_subscriptions', {
+    data: subscription,
+  }).then(response => response.data);
+
+// Last one checks for payload support: https://web-push-book.gauntface.com/chapter-06/01-non-standards-browsers/#no-payload
+const supportsPushNotifications = ('serviceWorker' in navigator && 'PushManager' in window && 'getKey' in PushSubscription.prototype);
+
+export function register () {
+  store.dispatch(setBrowserSupport(supportsPushNotifications));
+
+  if (supportsPushNotifications) {
+    if (!getApplicationServerKey()) {
+      // eslint-disable-next-line no-console
+      console.error('The VAPID public key is not set. You will not be able to receive Web Push Notifications.');
+      return;
+    }
+
+    getRegistration()
+      .then(getPushSubscription)
+      .then(({ registration, subscription }) => {
+        if (subscription !== null) {
+          // We have a subscription, check if it is still valid
+          const currentServerKey = (new Uint8Array(subscription.options.applicationServerKey)).toString();
+          const subscriptionServerKey = urlBase64ToUint8Array(getApplicationServerKey()).toString();
+          const serverEndpoint = store.getState().getIn(['push_notifications', 'subscription', 'endpoint']);
+
+          // If the VAPID public key did not change and the endpoint corresponds
+          // to the endpoint saved in the backend, the subscription is valid
+          if (subscriptionServerKey === currentServerKey && subscription.endpoint === serverEndpoint) {
+            return subscription;
+          } else {
+            // Something went wrong, try to subscribe again
+            return unsubscribe({ registration, subscription }).then(subscribe).then(sendSubscriptionToBackend);
+          }
+        }
+
+        // No subscription, try to subscribe
+        return subscribe(registration).then(sendSubscriptionToBackend);
+      })
+      .then(subscription => {
+        // If we got a PushSubscription (and not a subscription object from the backend)
+        // it means that the backend subscription is valid (and was set during hydration)
+        if (!(subscription instanceof PushSubscription)) {
+          store.dispatch(setSubscription(subscription));
+        }
+      })
+      .catch(error => {
+        if (error.code === 20 && error.name === 'AbortError') {
+          // eslint-disable-next-line no-console
+          console.warn('Your browser supports Web Push Notifications, but does not seem to implement the VAPID protocol.');
+        } else if (error.code === 5 && error.name === 'InvalidCharacterError') {
+          // eslint-disable-next-line no-console
+          console.error('The VAPID public key seems to be invalid:', getApplicationServerKey());
+        }
+
+        // Clear alerts and hide UI settings
+        store.dispatch(clearSubscription());
+
+        try {
+          getRegistration()
+            .then(getPushSubscription)
+            .then(unsubscribe);
+        } catch (e) {
+
+        }
+      });
+  } else {
+    // eslint-disable-next-line no-console
+    console.warn('Your browser does not support Web Push Notifications.');
+  }
+}
diff --git a/app/javascript/styles/components.scss b/app/javascript/styles/components.scss
index 45dd9f914..02602afa4 100644
--- a/app/javascript/styles/components.scss
+++ b/app/javascript/styles/components.scss
@@ -2352,7 +2352,8 @@ button.icon-button.active i.fa-retweet {
   line-height: 24px;
 }
 
-.setting-toggle__label {
+.setting-toggle__label,
+.setting-meta__label {
   color: $ui-primary-color;
   display: inline-block;
   margin-bottom: 14px;
@@ -2360,6 +2361,11 @@ button.icon-button.active i.fa-retweet {
   vertical-align: middle;
 }
 
+.setting-meta__label {
+  color: $ui-primary-color;
+  float: right;
+}
+
 .empty-column-indicator,
 .error-column {
   color: lighten($ui-base-color, 20%);
diff --git a/app/javascript/styles/rtl.scss b/app/javascript/styles/rtl.scss
index a91d0d72a..4966fbc21 100644
--- a/app/javascript/styles/rtl.scss
+++ b/app/javascript/styles/rtl.scss
@@ -45,6 +45,10 @@ body.rtl {
     margin-right: 8px;
   }
 
+  .setting-meta__label {
+    float: left;
+  }
+
   .status__avatar {
     left: auto;
     right: 10px;
diff --git a/app/models/session_activation.rb b/app/models/session_activation.rb
index 887e3e3bd..7eb16af8f 100644
--- a/app/models/session_activation.rb
+++ b/app/models/session_activation.rb
@@ -3,6 +3,17 @@
 #
 # Table name: session_activations
 #
+#  id                       :integer          not null, primary key
+#  user_id                  :integer          not null
+#  session_id               :string           not null
+#  created_at               :datetime         not null
+#  updated_at               :datetime         not null
+#  user_agent               :string           default(""), not null
+#  ip                       :inet
+#  access_token_id          :integer
+#  web_push_subscription_id :integer
+#
+
 #  id              :integer          not null, primary key
 #  user_id         :integer          not null
 #  session_id      :string           not null
@@ -15,6 +26,7 @@
 
 class SessionActivation < ApplicationRecord
   belongs_to :access_token, class_name: 'Doorkeeper::AccessToken', dependent: :destroy
+  belongs_to :web_push_subscription, class_name: 'Web::PushSubscription', dependent: :destroy
 
   delegate :token,
            to: :access_token,
diff --git a/app/models/user.rb b/app/models/user.rb
index 86e578225..a63b1da7f 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -113,6 +113,10 @@ class User < ApplicationRecord
     session_activations.active? id
   end
 
+  def web_push_subscription(session)
+    session.web_push_subscription.nil? ? nil : session.web_push_subscription.as_payload
+  end
+
   protected
 
   def send_devise_notification(notification, *args)
diff --git a/app/models/web/push_subscription.rb b/app/models/web/push_subscription.rb
new file mode 100644
index 000000000..4440706a6
--- /dev/null
+++ b/app/models/web/push_subscription.rb
@@ -0,0 +1,190 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: web_push_subscriptions
+#
+#  id         :integer          not null, primary key
+#  endpoint   :string           not null
+#  key_p256dh :string           not null
+#  key_auth   :string           not null
+#  data       :json
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+
+class Web::PushSubscription < ApplicationRecord
+  include RoutingHelper
+  include StreamEntriesHelper
+  include ActionView::Helpers::TranslationHelper
+  include ActionView::Helpers::SanitizeHelper
+
+  has_one :session_activation
+
+  before_create :send_welcome_notification
+
+  def push(notification)
+    return unless pushable? notification
+
+    name = display_name notification.from_account
+    title = title_str(name, notification)
+    body = body_str notification
+    dir = dir_str body
+    url = url_str notification
+    image = image_str notification
+    actions = actions_arr notification
+
+    access_token = actions.empty? ? nil : find_or_create_access_token(notification).token
+    nsfw = notification.target_status.nil? || notification.target_status.spoiler_text.empty? ? nil : notification.target_status.spoiler_text
+
+    # TODO: Make sure that the payload does not exceed 4KB - Webpush::PayloadTooLarge
+    # TODO: Queue the requests - Webpush::TooManyRequests
+    Webpush.payload_send(
+      message: JSON.generate(
+        title: title,
+        dir: dir,
+        image: image,
+        badge: full_asset_url('badge.png'),
+        tag: notification.id,
+        timestamp: notification.created_at,
+        icon: notification.from_account.avatar_static_url,
+        data: {
+          content: decoder.decode(strip_tags(body)),
+          nsfw: nsfw.nil? ? nil : decoder.decode(strip_tags(nsfw)),
+          url: url,
+          actions: actions,
+          access_token: access_token,
+        }
+      ),
+      endpoint: endpoint,
+      p256dh: key_p256dh,
+      auth: key_auth,
+      vapid: {
+        # subject: "mailto:#{Setting.site_contact_email}",
+        private_key: Rails.configuration.x.vapid_private_key,
+        public_key: Rails.configuration.x.vapid_public_key,
+      },
+      ttl: 40 * 60 * 60 # 48 hours
+    )
+  end
+
+  def as_payload
+    payload = {
+      id: id,
+      endpoint: endpoint,
+    }
+
+    payload[:alerts] = data['alerts'] if data && data.key?('alerts')
+
+    payload
+  end
+
+  private
+
+  def title_str(name, notification)
+    case notification.type
+    when :mention then translate('push_notifications.mention.title', name: name)
+    when :follow then translate('push_notifications.follow.title', name: name)
+    when :favourite then translate('push_notifications.favourite.title', name: name)
+    when :reblog then translate('push_notifications.reblog.title', name: name)
+    end
+  end
+
+  def body_str(notification)
+    case notification.type
+    when :mention then notification.target_status.text
+    when :follow then notification.from_account.note
+    when :favourite then notification.target_status.text
+    when :reblog then notification.target_status.text
+    end
+  end
+
+  def url_str(notification)
+    case notification.type
+    when :mention then web_url("statuses/#{notification.target_status.id}")
+    when :follow then web_url("accounts/#{notification.from_account.id}")
+    when :favourite then web_url("statuses/#{notification.target_status.id}")
+    when :reblog then web_url("statuses/#{notification.target_status.id}")
+    end
+  end
+
+  def actions_arr(notification)
+    actions =
+      case notification.type
+      when :mention then [
+        {
+          title: translate('push_notifications.mention.action_favourite'),
+          icon: full_asset_url('emoji/2764.png'),
+          todo: 'request',
+          method: 'POST',
+          action: "/api/v1/statuses/#{notification.target_status.id}/favourite",
+        },
+      ]
+      else []
+      end
+
+    should_hide = notification.type.equal?(:mention) && !notification.target_status.nil? && (notification.target_status.sensitive || !notification.target_status.spoiler_text.empty?)
+    can_boost = notification.type.equal?(:mention) && !notification.target_status.nil? && !notification.target_status.hidden?
+
+    if should_hide
+      actions.insert(0, title: translate('push_notifications.mention.action_expand'), icon: full_asset_url('emoji/1f441.png'), todo: 'expand', action: 'expand')
+    end
+
+    if can_boost
+      actions << { title: translate('push_notifications.mention.action_boost'), icon: full_asset_url('emoji/1f504.png'), todo: 'request', method: 'POST', action: "/api/v1/statuses/#{notification.target_status.id}/reblog" }
+    end
+
+    actions
+  end
+
+  def image_str(notification)
+    return nil if notification.target_status.nil? || notification.target_status.media_attachments.empty?
+
+    full_asset_url(notification.target_status.media_attachments.first.file.url(:small))
+  end
+
+  def dir_str(body)
+    rtl?(body) ? 'rtl' : 'ltr'
+  end
+
+  def pushable?(notification)
+    data && data.key?('alerts') && data['alerts'][notification.type.to_s]
+  end
+
+  def send_welcome_notification
+    Webpush.payload_send(
+      message: JSON.generate(
+        title: translate('push_notifications.subscribed.title'),
+        icon: full_asset_url('android-chrome-192x192.png'),
+        badge: full_asset_url('badge.png'),
+        data: {
+          content: translate('push_notifications.subscribed.body'),
+          actions: [],
+          url: web_url('notifications'),
+        }
+      ),
+      endpoint: endpoint,
+      p256dh: key_p256dh,
+      auth: key_auth,
+      vapid: {
+        # subject: "mailto:#{Setting.site_contact_email}",
+        private_key: Rails.configuration.x.vapid_private_key,
+        public_key: Rails.configuration.x.vapid_public_key,
+      },
+      ttl: 5 * 60 # 5 minutes
+    )
+  end
+
+  def find_or_create_access_token(notification)
+    Doorkeeper::AccessToken.find_or_create_for(
+      Doorkeeper::Application.find_by(superapp: true),
+      notification.account.user.id,
+      Doorkeeper::OAuth::Scopes.from_string('read write follow'),
+      Doorkeeper.configuration.access_token_expires_in,
+      Doorkeeper.configuration.refresh_token_enabled?
+    )
+  end
+
+  def decoder
+    @decoder ||= HTMLEntities.new
+  end
+end
diff --git a/app/presenters/initial_state_presenter.rb b/app/presenters/initial_state_presenter.rb
index 75fef28a8..9507aad4a 100644
--- a/app/presenters/initial_state_presenter.rb
+++ b/app/presenters/initial_state_presenter.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 class InitialStatePresenter < ActiveModelSerializers::Model
-  attributes :settings, :token, :current_account, :admin
+  attributes :settings, :push_subscription, :token, :current_account, :admin
 end
diff --git a/app/serializers/initial_state_serializer.rb b/app/serializers/initial_state_serializer.rb
index 6751c9411..704d29a57 100644
--- a/app/serializers/initial_state_serializer.rb
+++ b/app/serializers/initial_state_serializer.rb
@@ -2,7 +2,7 @@
 
 class InitialStateSerializer < ActiveModel::Serializer
   attributes :meta, :compose, :accounts,
-             :media_attachments, :settings
+             :media_attachments, :settings, :push_subscription
 
   def meta
     store = {
diff --git a/app/services/notify_service.rb b/app/services/notify_service.rb
index 407d385ea..0ab61b634 100644
--- a/app/services/notify_service.rb
+++ b/app/services/notify_service.rb
@@ -61,6 +61,11 @@ class NotifyService < BaseService
     @notification.save!
     return unless @notification.browserable?
     Redis.current.publish("timeline:#{@recipient.id}", Oj.dump(event: :notification, payload: InlineRenderer.render(@notification, @recipient, :notification)))
+    send_push_notifications
+  end
+
+  def send_push_notifications
+    WebPushNotificationWorker.perform_async(@recipient.id, @notification.id)
   end
 
   def send_email
diff --git a/app/views/home/index.html.haml b/app/views/home/index.html.haml
index 71dcb54c6..13ca9ea79 100644
--- a/app/views/home/index.html.haml
+++ b/app/views/home/index.html.haml
@@ -1,4 +1,5 @@
 - content_for :header_tags do
+  %meta{name: 'applicationServerKey', content: Rails.configuration.x.vapid_public_key}
   %script#initial-state{ type: 'application/json' }!= json_escape(@initial_state_json)
 
   = javascript_pack_tag 'application', integrity: true, crossorigin: 'anonymous'
diff --git a/app/workers/web_push_notification_worker.rb b/app/workers/web_push_notification_worker.rb
new file mode 100644
index 000000000..0568a3e02
--- /dev/null
+++ b/app/workers/web_push_notification_worker.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class WebPushNotificationWorker
+  include Sidekiq::Worker
+
+  sidekiq_options backtrace: true
+
+  def perform(recipient_id, notification_id)
+    recipient = Account.find(recipient_id)
+    notification = Notification.find(notification_id)
+
+    sessions_with_subscriptions = recipient.user.session_activations.reject { |session| session.web_push_subscription.nil? }
+
+    sessions_with_subscriptions.each do |session|
+      begin
+        session.web_push_subscription.push(notification)
+      rescue Webpush::InvalidSubscription, Webpush::ExpiredSubscription
+        # Subscription expiration is not currently implemented in any browser
+        session.web_push_subscription.destroy!
+        session.web_push_subscription = nil
+        session.save!
+      rescue Webpush::PayloadTooLarge => e
+        Rails.logger.error(e)
+      end
+    end
+  end
+end