Add onboarding prompt when home feed too slow in web UI (#25267)

app/javascript/mastodon/features/home_timeline/index.jsx

@@ -5,9 +5,10 @@ import { defineMessages, injectIntl, FormattedMessage } from 'react-intl';
 
 import classNames from 'classnames';
 import { Helmet } from 'react-helmet';
-import { Link } from 'react-router-dom';
 
+import { List as ImmutableList } from 'immutable';
 import { connect } from 'react-redux';
+import { createSelector } from 'reselect';
 
 import { fetchAnnouncements, toggleShowAnnouncements } from 'mastodon/actions/announcements';
 import { IconWithBadge } from 'mastodon/components/icon_with_badge';
@@ -20,6 +21,7 @@ import Column from '../../components/column';
 import ColumnHeader from '../../components/column_header';
 import StatusListContainer from '../ui/containers/status_list_container';
 
+import { ExplorePrompt } from './components/explore_prompt';
 import ColumnSettingsContainer from './containers/column_settings_container';
 
 const messages = defineMessages({
@@ -28,12 +30,36 @@ const messages = defineMessages({
   hide_announcements: { id: 'home.hide_announcements', defaultMessage: 'Hide announcements' },
 });
 
+const getHomeFeedSpeed = createSelector([
+  state => state.getIn(['timelines', 'home', 'items'], ImmutableList()),
+  state => state.get('statuses'),
+], (statusIds, statusMap) => {
+  const statuses = statusIds.take(20).map(id => statusMap.get(id));
+  const uniqueAccountIds = (new Set(statuses.map(status => status.get('account')).toArray())).size;
+  const oldest = new Date(statuses.getIn([statuses.size - 1, 'created_at'], 0));
+  const newest = new Date(statuses.getIn([0, 'created_at'], 0));
+  const averageGap = (newest - oldest) / (1000 * (statuses.size + 1)); // Average gap between posts on first page in seconds
+
+  return {
+    unique: uniqueAccountIds,
+    gap: averageGap,
+    newest,
+  };
+});
+
+const homeTooSlow = createSelector(getHomeFeedSpeed, speed =>
+  speed.unique < 5 // If there are fewer than 5 different accounts visible
+  || speed.gap > (30 * 60) // If the average gap between posts is more than 20 minutes
+  || (Date.now() - speed.newest) > (1000 * 3600) // If the most recent post is from over an hour ago
+);
+
 const mapStateToProps = state => ({
   hasUnread: state.getIn(['timelines', 'home', 'unread']) > 0,
   isPartial: state.getIn(['timelines', 'home', 'isPartial']),
   hasAnnouncements: !state.getIn(['announcements', 'items']).isEmpty(),
   unreadAnnouncements: state.getIn(['announcements', 'items']).count(item => !item.get('read')),
   showAnnouncements: state.getIn(['announcements', 'show']),
+  tooSlow: homeTooSlow(state),
 });
 
 class HomeTimeline extends PureComponent {
@@ -52,6 +78,7 @@ class HomeTimeline extends PureComponent {
     hasAnnouncements: PropTypes.bool,
     unreadAnnouncements: PropTypes.number,
     showAnnouncements: PropTypes.bool,
+    tooSlow: PropTypes.bool,
   };
 
   handlePin = () => {
@@ -121,11 +148,11 @@ class HomeTimeline extends PureComponent {
   };
 
   render () {
-    const { intl, hasUnread, columnId, multiColumn, hasAnnouncements, unreadAnnouncements, showAnnouncements } = this.props;
+    const { intl, hasUnread, columnId, multiColumn, tooSlow, hasAnnouncements, unreadAnnouncements, showAnnouncements } = this.props;
     const pinned = !!columnId;
     const { signedIn } = this.context.identity;
 
-    let announcementsButton = null;
+    let announcementsButton, banner;
 
     if (hasAnnouncements) {
       announcementsButton = (
@@ -141,6 +168,10 @@ class HomeTimeline extends PureComponent {
       );
     }
 
+    if (tooSlow) {
+      banner = <ExplorePrompt />;
+    }
+
     return (
       <Column bindToDocument={!multiColumn} ref={this.setRef} label={intl.formatMessage(messages.title)}>
         <ColumnHeader
@@ -160,11 +191,13 @@ class HomeTimeline extends PureComponent {
 
         {signedIn ? (
           <StatusListContainer
+            prepend={banner}
+            alwaysPrepend
             trackScroll={!pinned}
             scrollKey={`home_timeline-${columnId}`}
             onLoadMore={this.handleLoadMore}
             timelineId='home'
-            emptyMessage={<FormattedMessage id='empty_column.home' defaultMessage='Your home timeline is empty! Follow more people to fill it up. {suggestions}' values={{ suggestions: <Link to='/start'><FormattedMessage id='empty_column.home.suggestions' defaultMessage='See some suggestions' /></Link> }} />}
+            emptyMessage={<FormattedMessage id='empty_column.home' defaultMessage='Your home timeline is empty! Follow more people to fill it up.' />}
             bindToDocument={!multiColumn}
           />
         ) : <NotSignedInIndicator />}