Add unread notification markers (#14818)

* Add unread notification markers

Fixes #14804

* Allow IntersectionObserverArticle's children to be updated

9 files changed, 227 insertions, 33 deletions

diff --git a/app/javascript/mastodon/actions/markers.js b/app/javascript/mastodon/actions/markers.js
index 6cb09fe96..41a95503e 100644
--- a/app/javascript/mastodon/actions/markers.js
+++ b/app/javascript/mastodon/actions/markers.js
@@ -3,6 +3,9 @@ import { debounce } from 'lodash';
 import compareId from '../compare_id';
 import { showAlertForError } from './alerts';
 
+export const MARKERS_FETCH_REQUEST = 'MARKERS_FETCH_REQUEST';
+export const MARKERS_FETCH_SUCCESS = 'MARKERS_FETCH_SUCCESS';
+export const MARKERS_FETCH_FAIL    = 'MARKERS_FETCH_FAIL';
 export const MARKERS_SUBMIT_SUCCESS = 'MARKERS_SUBMIT_SUCCESS';
 
 export const synchronouslySubmitMarkers = () => (dispatch, getState) => {
@@ -58,7 +61,7 @@ const _buildParams = (state) => {
   const params = {};
 
   const lastHomeId         = state.getIn(['timelines', 'home', 'items']).find(item => item !== null);
-  const lastNotificationId = state.getIn(['notifications', 'items', 0, 'id']);
+  const lastNotificationId = state.getIn(['notifications', 'lastReadId']);
 
   if (lastHomeId && compareId(lastHomeId, state.getIn(['markers', 'home'])) > 0) {
     params.home = {
@@ -100,3 +103,39 @@ export function submitMarkersSuccess({ home, notifications }) {
 export function submitMarkers() {
   return (dispatch, getState) => debouncedSubmitMarkers(dispatch, getState);
 };
+
+export const fetchMarkers = () => (dispatch, getState) => {
+  const params = { timeline: ['notifications'] };
+
+  dispatch(fetchMarkersRequest());
+
+  api(getState).get('/api/v1/markers', { params }).then(response => {
+    dispatch(fetchMarkersSuccess(response.data));
+  }).catch(error => {
+    dispatch(fetchMarkersFail(error));
+  });
+};
+
+export function fetchMarkersRequest() {
+  return {
+    type: MARKERS_FETCH_REQUEST,
+    skipLoading: true,
+  };
+};
+
+export function fetchMarkersSuccess(markers) {
+  return {
+    type: MARKERS_FETCH_SUCCESS,
+    markers,
+    skipLoading: true,
+  };
+};
+
+export function fetchMarkersFail(error) {
+  return {
+    type: MARKERS_FETCH_FAIL,
+    error,
+    skipLoading: true,
+    skipAlert: true,
+  };
+};
diff --git a/app/javascript/mastodon/actions/notifications.js b/app/javascript/mastodon/actions/notifications.js
index 099e42f6c..552def63b 100644
--- a/app/javascript/mastodon/actions/notifications.js
+++ b/app/javascript/mastodon/actions/notifications.js
@@ -33,6 +33,8 @@ export const NOTIFICATIONS_LOAD_PENDING = 'NOTIFICATIONS_LOAD_PENDING';
 export const NOTIFICATIONS_MOUNT   = 'NOTIFICATIONS_MOUNT';
 export const NOTIFICATIONS_UNMOUNT = 'NOTIFICATIONS_UNMOUNT';
 
+export const NOTIFICATIONS_MARK_AS_READ = 'NOTIFICATIONS_MARK_AS_READ';
+
 defineMessages({
   mention: { id: 'notification.mention', defaultMessage: '{name} mentioned you' },
   group: { id: 'notifications.group', defaultMessage: '{count} notifications' },
diff --git a/app/javascript/mastodon/components/intersection_observer_article.js b/app/javascript/mastodon/components/intersection_observer_article.js
index 124b34b02..2d87f19b5 100644
--- a/app/javascript/mastodon/components/intersection_observer_article.js
+++ b/app/javascript/mastodon/components/intersection_observer_article.js
@@ -2,10 +2,7 @@ import React from 'react';
 import PropTypes from 'prop-types';
 import scheduleIdleTask from '../features/ui/util/schedule_idle_task';
 import getRectFromEntry from '../features/ui/util/get_rect_from_entry';
-import { is } from 'immutable';
 
-// Diff these props in the "rendered" state
-const updateOnPropsForRendered = ['id', 'index', 'listLength'];
 // Diff these props in the "unrendered" state
 const updateOnPropsForUnrendered = ['id', 'index', 'listLength', 'cachedHeight'];
 
@@ -33,9 +30,12 @@ export default class IntersectionObserverArticle extends React.Component {
       // If we're going from rendered to unrendered (or vice versa) then update
       return true;
     }
-    // Otherwise, diff based on props
-    const propsToDiff = isUnrendered ? updateOnPropsForUnrendered : updateOnPropsForRendered;
-    return !propsToDiff.every(prop => is(nextProps[prop], this.props[prop]));
+    // If we are and remain hidden, diff based on props
+    if (isUnrendered) {
+      return !updateOnPropsForUnrendered.every(prop => nextProps[prop] === this.props[prop]);
+    }
+    // Else, assume the children have changed
+    return true;
   }
 
   componentDidMount () {
diff --git a/app/javascript/mastodon/components/status.js b/app/javascript/mastodon/components/status.js
index 174e401b7..a1d6f27a6 100644
--- a/app/javascript/mastodon/components/status.js
+++ b/app/javascript/mastodon/components/status.js
@@ -104,6 +104,7 @@ class Status extends ImmutablePureComponent {
     'account',
     'muted',
     'hidden',
+    'unread',
   ];
 
   state = {
@@ -438,10 +439,10 @@ class Status extends ImmutablePureComponent {
 
     return (
       <HotKeys handlers={handlers}>
-        <div className={classNames('status__wrapper', `status__wrapper-${status.get('visibility')}`, { 'status__wrapper-reply': !!status.get('in_reply_to_id'), read: unread === false, focusable: !this.props.muted })} tabIndex={this.props.muted ? null : 0} data-featured={featured ? 'true' : null} aria-label={textForScreenReader(intl, status, rebloggedByText)} ref={this.handleRef}>
+        <div className={classNames('status__wrapper', `status__wrapper-${status.get('visibility')}`, { 'status__wrapper-reply': !!status.get('in_reply_to_id'), unread, focusable: !this.props.muted })} tabIndex={this.props.muted ? null : 0} data-featured={featured ? 'true' : null} aria-label={textForScreenReader(intl, status, rebloggedByText)} ref={this.handleRef}>
           {prepend}
 
-          <div className={classNames('status', `status-${status.get('visibility')}`, { 'status-reply': !!status.get('in_reply_to_id'), muted: this.props.muted, read: unread === false })} data-id={status.get('id')}>
+          <div className={classNames('status', `status-${status.get('visibility')}`, { 'status-reply': !!status.get('in_reply_to_id'), muted: this.props.muted })} data-id={status.get('id')}>
             <div className='status__expand' onClick={this.handleExpandClick} role='presentation' />
             <div className='status__info'>
               <a href={status.get('url')} className='status__relative-time' target='_blank' rel='noopener noreferrer'><RelativeTimestamp timestamp={status.get('created_at')} /></a>
diff --git a/app/javascript/mastodon/features/notifications/components/notification.js b/app/javascript/mastodon/features/notifications/components/notification.js
index 62a97f187..94fdbd6f4 100644
--- a/app/javascript/mastodon/features/notifications/components/notification.js
+++ b/app/javascript/mastodon/features/notifications/components/notification.js
@@ -10,6 +10,7 @@ import AccountContainer from 'mastodon/containers/account_container';
 import FollowRequestContainer from '../containers/follow_request_container';
 import Icon from 'mastodon/components/icon';
 import Permalink from 'mastodon/components/permalink';
+import classNames from 'classnames';
 
 const messages = defineMessages({
   favourite: { id: 'notification.favourite', defaultMessage: '{name} favourited your status' },
@@ -50,6 +51,7 @@ class Notification extends ImmutablePureComponent {
     updateScrollBottom: PropTypes.func,
     cacheMediaWidth: PropTypes.func,
     cachedMediaWidth: PropTypes.number,
+    unread: PropTypes.bool,
   };
 
   handleMoveUp = () => {
@@ -114,11 +116,11 @@ class Notification extends ImmutablePureComponent {
   }
 
   renderFollow (notification, account, link) {
-    const { intl } = this.props;
+    const { intl, unread } = this.props;
 
     return (
       <HotKeys handlers={this.getHandlers()}>
-        <div className='notification notification-follow focusable' tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage(messages.follow, { name: account.get('acct') }), notification.get('created_at'))}>
+        <div className={classNames('notification notification-follow focusable', { unread })} tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage(messages.follow, { name: account.get('acct') }), notification.get('created_at'))}>
           <div className='notification__message'>
             <div className='notification__favourite-icon-wrapper'>
               <Icon id='user-plus' fixedWidth />
@@ -136,11 +138,11 @@ class Notification extends ImmutablePureComponent {
   }
 
   renderFollowRequest (notification, account, link) {
-    const { intl } = this.props;
+    const { intl, unread } = this.props;
 
     return (
       <HotKeys handlers={this.getHandlers()}>
-        <div className='notification notification-follow-request focusable' tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage({ id: 'notification.follow_request', defaultMessage: '{name} has requested to follow you' }, { name: account.get('acct') }), notification.get('created_at'))}>
+        <div className={classNames('notification notification-follow-request focusable', { unread })} tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage({ id: 'notification.follow_request', defaultMessage: '{name} has requested to follow you' }, { name: account.get('acct') }), notification.get('created_at'))}>
           <div className='notification__message'>
             <div className='notification__favourite-icon-wrapper'>
               <Icon id='user' fixedWidth />
@@ -170,16 +172,17 @@ class Notification extends ImmutablePureComponent {
         updateScrollBottom={this.props.updateScrollBottom}
         cachedMediaWidth={this.props.cachedMediaWidth}
         cacheMediaWidth={this.props.cacheMediaWidth}
+        unread={this.props.unread}
       />
     );
   }
 
   renderFavourite (notification, link) {
-    const { intl } = this.props;
+    const { intl, unread } = this.props;
 
     return (
       <HotKeys handlers={this.getHandlers()}>
-        <div className='notification notification-favourite focusable' tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage(messages.favourite, { name: notification.getIn(['account', 'acct']) }), notification.get('created_at'))}>
+        <div className={classNames('notification notification-favourite focusable', { unread })} tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage(messages.favourite, { name: notification.getIn(['account', 'acct']) }), notification.get('created_at'))}>
           <div className='notification__message'>
             <div className='notification__favourite-icon-wrapper'>
               <Icon id='star' className='star-icon' fixedWidth />
@@ -207,11 +210,11 @@ class Notification extends ImmutablePureComponent {
   }
 
   renderReblog (notification, link) {
-    const { intl } = this.props;
+    const { intl, unread } = this.props;
 
     return (
       <HotKeys handlers={this.getHandlers()}>
-        <div className='notification notification-reblog focusable' tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage(messages.reblog, { name: notification.getIn(['account', 'acct']) }), notification.get('created_at'))}>
+        <div className={classNames('notification notification-reblog focusable', { unread })} tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage(messages.reblog, { name: notification.getIn(['account', 'acct']) }), notification.get('created_at'))}>
           <div className='notification__message'>
             <div className='notification__favourite-icon-wrapper'>
               <Icon id='retweet' fixedWidth />
@@ -239,11 +242,11 @@ class Notification extends ImmutablePureComponent {
   }
 
   renderStatus (notification, link) {
-    const { intl } = this.props;
+    const { intl, unread } = this.props;
 
     return (
       <HotKeys handlers={this.getHandlers()}>
-        <div className='notification notification-status focusable' tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage(messages.status, { name: notification.getIn(['account', 'acct']) }), notification.get('created_at'))}>
+        <div className={classNames('notification notification-status focusable', { unread })} tabIndex='0' aria-label={notificationForScreenReader(intl, intl.formatMessage(messages.status, { name: notification.getIn(['account', 'acct']) }), notification.get('created_at'))}>
           <div className='notification__message'>
             <div className='notification__favourite-icon-wrapper'>
               <Icon id='home' fixedWidth />
@@ -271,13 +274,13 @@ class Notification extends ImmutablePureComponent {
   }
 
   renderPoll (notification, account) {
-    const { intl } = this.props;
+    const { intl, unread } = this.props;
     const ownPoll  = me === account.get('id');
     const message  = ownPoll ? intl.formatMessage(messages.ownPoll) : intl.formatMessage(messages.poll);
 
     return (
       <HotKeys handlers={this.getHandlers()}>
-        <div className='notification notification-poll focusable' tabIndex='0' aria-label={notificationForScreenReader(intl, message, notification.get('created_at'))}>
+        <div className={classNames('notification notification-poll focusable', { unread })} tabIndex='0' aria-label={notificationForScreenReader(intl, message, notification.get('created_at'))}>
           <div className='notification__message'>
             <div className='notification__favourite-icon-wrapper'>
               <Icon id='tasks' fixedWidth />
diff --git a/app/javascript/mastodon/features/notifications/index.js b/app/javascript/mastodon/features/notifications/index.js
index 6ff376780..41a45b2b6 100644
--- a/app/javascript/mastodon/features/notifications/index.js
+++ b/app/javascript/mastodon/features/notifications/index.js
@@ -4,7 +4,14 @@ import PropTypes from 'prop-types';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import Column from '../../components/column';
 import ColumnHeader from '../../components/column_header';
-import { expandNotifications, scrollTopNotifications, loadPending, mountNotifications, unmountNotifications } from '../../actions/notifications';
+import {
+  expandNotifications,
+  scrollTopNotifications,
+  loadPending,
+  mountNotifications,
+  unmountNotifications,
+  markNotificationsAsRead,
+} from '../../actions/notifications';
 import { addColumn, removeColumn, moveColumn } from '../../actions/columns';
 import NotificationContainer from './containers/notification_container';
 import { defineMessages, injectIntl, FormattedMessage } from 'react-intl';
@@ -15,9 +22,12 @@ import { List as ImmutableList } from 'immutable';
 import { debounce } from 'lodash';
 import ScrollableList from '../../components/scrollable_list';
 import LoadGap from '../../components/load_gap';
+import Icon from 'mastodon/components/icon';
+import compareId from 'mastodon/compare_id';
 
 const messages = defineMessages({
   title: { id: 'column.notifications', defaultMessage: 'Notifications' },
+  markAsRead : { id: 'notifications.mark_as_read', defaultMessage: 'Mark every notification as read' },
 });
 
 const getNotifications = createSelector([
@@ -42,6 +52,8 @@ const mapStateToProps = state => ({
   isUnread: state.getIn(['notifications', 'unread']) > 0 || state.getIn(['notifications', 'pendingItems']).size > 0,
   hasMore: state.getIn(['notifications', 'hasMore']),
   numPending: state.getIn(['notifications', 'pendingItems'], ImmutableList()).size,
+  lastReadId: state.getIn(['notifications', 'readMarkerId']),
+  canMarkAsRead: state.getIn(['notifications', 'readMarkerId']) !== '0' && getNotifications(state).some(item => item !== null && compareId(item.get('id'), state.getIn(['notifications', 'readMarkerId'])) > 0),
 });
 
 export default @connect(mapStateToProps)
@@ -60,6 +72,8 @@ class Notifications extends React.PureComponent {
     multiColumn: PropTypes.bool,
     hasMore: PropTypes.bool,
     numPending: PropTypes.number,
+    lastReadId: PropTypes.string,
+    canMarkAsRead: PropTypes.bool,
   };
 
   static defaultProps = {
@@ -146,8 +160,12 @@ class Notifications extends React.PureComponent {
     }
   }
 
+  handleMarkAsRead = () => {
+    this.props.dispatch(markNotificationsAsRead());
+  };
+
   render () {
-    const { intl, notifications, shouldUpdateScroll, isLoading, isUnread, columnId, multiColumn, hasMore, numPending, showFilterBar } = this.props;
+    const { intl, notifications, shouldUpdateScroll, isLoading, isUnread, columnId, multiColumn, hasMore, numPending, showFilterBar, lastReadId, canMarkAsRead } = this.props;
     const pinned = !!columnId;
     const emptyMessage = <FormattedMessage id='empty_column.notifications' defaultMessage="You don't have any notifications yet. Interact with others to start the conversation." />;
 
@@ -174,6 +192,7 @@ class Notifications extends React.PureComponent {
           accountId={item.get('account')}
           onMoveUp={this.handleMoveUp}
           onMoveDown={this.handleMoveDown}
+          unread={lastReadId !== '0' && compareId(item.get('id'), lastReadId) > 0}
         />
       ));
     } else {
@@ -202,6 +221,21 @@ class Notifications extends React.PureComponent {
       </ScrollableList>
     );
 
+    let extraButton = null;
+
+    if (canMarkAsRead) {
+      extraButton = (
+        <button
+          aria-label={intl.formatMessage(messages.markAsRead)}
+          title={intl.formatMessage(messages.markAsRead)}
+          onClick={this.handleMarkAsRead}
+          className='column-header__button'
+        >
+          <Icon id='check' />
+        </button>
+      );
+    }
+
     return (
       <Column bindToDocument={!multiColumn} ref={this.setColumnRef} label={intl.formatMessage(messages.title)}>
         <ColumnHeader
@@ -213,6 +247,7 @@ class Notifications extends React.PureComponent {
           onClick={this.handleHeaderClick}
           pinned={pinned}
           multiColumn={multiColumn}
+          extraButton={extraButton}
         >
           <ColumnSettingsContainer />
         </ColumnHeader>
diff --git a/app/javascript/mastodon/features/ui/index.js b/app/javascript/mastodon/features/ui/index.js
index 553cb3365..5a0cf3b90 100644
--- a/app/javascript/mastodon/features/ui/index.js
+++ b/app/javascript/mastodon/features/ui/index.js
@@ -16,7 +16,7 @@ import { expandNotifications } from '../../actions/notifications';
 import { fetchFilters } from '../../actions/filters';
 import { clearHeight } from '../../actions/height_cache';
 import { focusApp, unfocusApp } from 'mastodon/actions/app';
-import { synchronouslySubmitMarkers } from 'mastodon/actions/markers';
+import { synchronouslySubmitMarkers, submitMarkers, fetchMarkers } from 'mastodon/actions/markers';
 import { WrappedSwitch, WrappedRoute } from './util/react_router_helpers';
 import UploadArea from './components/upload_area';
 import ColumnsAreaContainer from './containers/columns_area_container';
@@ -265,6 +265,7 @@ class UI extends React.PureComponent {
 
   handleWindowFocus = () => {
     this.props.dispatch(focusApp());
+    this.props.dispatch(submitMarkers());
   }
 
   handleWindowBlur = () => {
@@ -368,6 +369,7 @@ class UI extends React.PureComponent {
       window.setTimeout(() => Notification.requestPermission(), 120 * 1000);
     }
 
+    this.props.dispatch(fetchMarkers());
     this.props.dispatch(expandHomeTimeline());
     this.props.dispatch(expandNotifications());
 
diff --git a/app/javascript/mastodon/reducers/notifications.js b/app/javascript/mastodon/reducers/notifications.js
index ed1ba0272..b01db806f 100644
--- a/app/javascript/mastodon/reducers/notifications.js
+++ b/app/javascript/mastodon/reducers/notifications.js
@@ -9,6 +9,7 @@ import {
   NOTIFICATIONS_LOAD_PENDING,
   NOTIFICATIONS_MOUNT,
   NOTIFICATIONS_UNMOUNT,
+  NOTIFICATIONS_MARK_AS_READ,
 } from '../actions/notifications';
 import {
   ACCOUNT_BLOCK_SUCCESS,
@@ -16,6 +17,13 @@ import {
   FOLLOW_REQUEST_AUTHORIZE_SUCCESS,
   FOLLOW_REQUEST_REJECT_SUCCESS,
 } from '../actions/accounts';
+import {
+  MARKERS_FETCH_SUCCESS,
+} from '../actions/markers';
+import {
+  APP_FOCUS,
+  APP_UNFOCUS,
+} from '../actions/app';
 import { DOMAIN_BLOCK_SUCCESS } from 'mastodon/actions/domain_blocks';
 import { TIMELINE_DELETE, TIMELINE_DISCONNECT } from '../actions/timelines';
 import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
@@ -26,8 +34,11 @@ const initialState = ImmutableMap({
   items: ImmutableList(),
   hasMore: true,
   top: false,
-  mounted: false,
+  mounted: 0,
   unread: 0,
+  lastReadId: '0',
+  readMarkerId: '0',
+  isTabVisible: true,
   isLoading: false,
 });
 
@@ -46,8 +57,10 @@ const normalizeNotification = (state, notification, usePendingItems) => {
     return state.update('pendingItems', list => list.unshift(notificationToMap(notification))).update('unread', unread => unread + 1);
   }
 
-  if (!top) {
+  if (shouldCountUnreadNotifications(state)) {
     state = state.update('unread', unread => unread + 1);
+  } else {
+    state = state.set('lastReadId', notification.id);
   }
 
   return state.update('items', list => {
@@ -60,6 +73,7 @@ const normalizeNotification = (state, notification, usePendingItems) => {
 };
 
 const expandNormalizedNotifications = (state, notifications, next, isLoadingRecent, usePendingItems) => {
+  const lastReadId = state.get('lastReadId');
   let items = ImmutableList();
 
   notifications.forEach((n, i) => {
@@ -87,6 +101,15 @@ const expandNormalizedNotifications = (state, notifications, next, isLoadingRece
       mutable.set('hasMore', false);
     }
 
+    if (shouldCountUnreadNotifications(state)) {
+      mutable.update('unread', unread => unread + items.count(item => compareId(item.get('id'), lastReadId) > 0));
+    } else {
+      const mostRecent = items.find(item => item !== null);
+      if (mostRecent && compareId(lastReadId, mostRecent.get('id')) < 0) {
+        mutable.set('lastReadId', mostRecent.get('id'));
+      }
+    }
+
     mutable.set('isLoading', false);
   });
 };
@@ -96,21 +119,92 @@ const filterNotifications = (state, accountIds, type) => {
   return state.update('items', helper).update('pendingItems', helper);
 };
 
+const clearUnread = (state) => {
+  state = state.set('unread', state.get('pendingItems').size);
+  const lastNotification = state.get('items').find(item => item !== null);
+  return state.set('lastReadId', lastNotification ? lastNotification.get('id') : '0');
+};
+
 const updateTop = (state, top) => {
-  if (top) {
-    state = state.set('unread', state.get('pendingItems').size);
+  state = state.set('top', top);
+
+  if (!shouldCountUnreadNotifications(state)) {
+    state = clearUnread(state);
   }
 
-  return state.set('top', top);
+  return state;
 };
 
 const deleteByStatus = (state, statusId) => {
+  const lastReadId = state.get('lastReadId');
+
+  if (shouldCountUnreadNotifications(state)) {
+    const deletedUnread = state.get('items').filter(item => item !== null && item.get('status') === statusId && compareId(item.get('id'), lastReadId) > 0);
+    state = state.update('unread', unread => unread - deletedUnread.size);
+  }
+
   const helper = list => list.filterNot(item => item !== null && item.get('status') === statusId);
+  const deletedUnread = state.get('pendingItems').filter(item => item !== null && item.get('status') === statusId && compareId(item.get('id'), lastReadId) > 0);
+  state = state.update('unread', unread => unread - deletedUnread.size);
   return state.update('items', helper).update('pendingItems', helper);
 };
 
+const updateMounted = (state) => {
+  state = state.update('mounted', count => count + 1);
+  if (!shouldCountUnreadNotifications(state)) {
+    state = state.set('readMarkerId', state.get('lastReadId'));
+    state = clearUnread(state);
+  }
+  return state;
+};
+
+const updateVisibility = (state, visibility) => {
+  state = state.set('isTabVisible', visibility);
+  if (!shouldCountUnreadNotifications(state)) {
+    state = state.set('readMarkerId', state.get('lastReadId'));
+    state = clearUnread(state);
+  }
+  return state;
+};
+
+const shouldCountUnreadNotifications = (state) => {
+  const isTabVisible   = state.get('isTabVisible');
+  const isOnTop        = state.get('top');
+  const isMounted      = state.get('mounted') > 0;
+  const lastReadId     = state.get('lastReadId');
+  const lastItemReached = !state.get('hasMore') || lastReadId === '0' || (!state.get('items').isEmpty() && compareId(state.get('items').last().get('id'), lastReadId) <= 0);
+
+  return !(isTabVisible && isOnTop && isMounted && lastItemReached);
+};
+
+const recountUnread = (state, last_read_id) => {
+  return state.withMutations(mutable => {
+    if (compareId(last_read_id, mutable.get('lastReadId')) > 0) {
+      mutable.set('lastReadId', last_read_id);
+    }
+
+    if (compareId(last_read_id, mutable.get('readMarkerId')) > 0) {
+      mutable.set('readMarkerId', last_read_id);
+    }
+
+    if (state.get('unread') > 0 || shouldCountUnreadNotifications(state)) {
+      mutable.set('unread', mutable.get('pendingItems').count(item => item !== null) + mutable.get('items').count(item => item && compareId(item.get('id'), last_read_id) > 0));
+    }
+  });
+};
+
 export default function notifications(state = initialState, action) {
   switch(action.type) {
+  case MARKERS_FETCH_SUCCESS:
+    return action.markers.notifications ? recountUnread(state, action.markers.notifications.last_read_id) : state;
+  case NOTIFICATIONS_MOUNT:
+    return updateMounted(state);
+  case NOTIFICATIONS_UNMOUNT:
+    return state.update('mounted', count => count - 1);
+  case APP_FOCUS:
+    return updateVisibility(state, true);
+  case APP_UNFOCUS:
+    return updateVisibility(state, false);
   case NOTIFICATIONS_LOAD_PENDING:
     return state.update('items', list => state.get('pendingItems').concat(list.take(40))).set('pendingItems', ImmutableList()).set('unread', 0);
   case NOTIFICATIONS_EXPAND_REQUEST:
@@ -144,10 +238,9 @@ export default function notifications(state = initialState, action) {
     return action.timeline === 'home' ?
       state.update(action.usePendingItems ? 'pendingItems' : 'items', items => items.first() ? items.unshift(null) : items) :
       state;
-  case NOTIFICATIONS_MOUNT:
-    return state.set('mounted', true);
-  case NOTIFICATIONS_UNMOUNT:
-    return state.set('mounted', false);
+  case NOTIFICATIONS_MARK_AS_READ:
+    const lastNotification = state.get('items').find(item => item !== null);
+    return lastNotification ? recountUnread(state, lastNotification.get('id')) : state;
   default:
     return state;
   }
diff --git a/app/javascript/styles/mastodon/components.scss b/app/javascript/styles/mastodon/components.scss
index 7defa0d16..5e79b4a11 100644
--- a/app/javascript/styles/mastodon/components.scss
+++ b/app/javascript/styles/mastodon/components.scss
@@ -7015,3 +7015,22 @@ noscript {
     }
   }
 }
+
+.notification,
+.status__wrapper {
+  position: relative;
+
+  &.unread {
+    &::before {
+      content: "";
+      position: absolute;
+      top: 0;
+      left: 0;
+      pointer-events: 0;
+      width: 100%;
+      height: 100%;
+      border-left: 2px solid $highlight-text-color;
+      pointer-events: none;
+    }
+  }
+}