Track trending tags (#7638)

* Track trending tags

- Half-life of 1 day
- Historical usage in daily buckets (last 7 days stored)
- GET /api/v1/trends

Fix #271

* Add trends to web UI

* Don't render compose form on search route, adjust search results header

* Disqualify tag from trends if it's in disallowed hashtags setting

* Count distinct accounts using tag, ignore silenced accounts

app/javascript/mastodon/features/compose/components/search_results.js

@@ -1,23 +1,75 @@
 import React from 'react';
+import PropTypes from 'prop-types';
 import ImmutablePropTypes from 'react-immutable-proptypes';
-import { FormattedMessage } from 'react-intl';
+import { FormattedMessage, FormattedNumber } from 'react-intl';
 import AccountContainer from '../../../containers/account_container';
 import StatusContainer from '../../../containers/status_container';
 import { Link } from 'react-router-dom';
 import ImmutablePureComponent from 'react-immutable-pure-component';
+import { Sparklines, SparklinesCurve } from 'react-sparklines';
+
+const shortNumberFormat = number => {
+  if (number < 1000) {
+    return <FormattedNumber value={number} />;
+  } else {
+    return <React.Fragment><FormattedNumber value={number / 1000} maximumFractionDigits={1} />K</React.Fragment>;
+  }
+};
 
 export default class SearchResults extends ImmutablePureComponent {
 
   static propTypes = {
     results: ImmutablePropTypes.map.isRequired,
+    trends: ImmutablePropTypes.list,
+    fetchTrends: PropTypes.func.isRequired,
   };
 
+  componentDidMount () {
+    const { fetchTrends } = this.props;
+    fetchTrends();
+  }
+
   render () {
-    const { results } = this.props;
+    const { results, trends } = this.props;
 
     let accounts, statuses, hashtags;
     let count = 0;
 
+    if (results.isEmpty()) {
+      return (
+        <div className='search-results'>
+          <div className='trends'>
+            <div className='trends__header'>
+              <i className='fa fa-fire fa-fw' />
+              <FormattedMessage id='trends.header' defaultMessage='Trending now' />
+            </div>
+
+            {trends && trends.map(hashtag => (
+              <div className='trends__item' key={hashtag.get('name')}>
+                <div className='trends__item__name'>
+                  <Link to={`/timelines/tag/${hashtag.get('name')}`}>
+                    #<span>{hashtag.get('name')}</span>
+                  </Link>
+
+                  <FormattedMessage id='trends.count_by_accounts' defaultMessage='{count} {rawCount, plural, one {person} other {people}} talking' values={{ rawCount: hashtag.getIn(['history', 0, 'accounts']), count: <strong>{shortNumberFormat(hashtag.getIn(['history', 0, 'accounts']))}</strong> }} />
+                </div>
+
+                <div className='trends__item__current'>
+                  {shortNumberFormat(hashtag.getIn(['history', 0, 'uses']))}
+                </div>
+
+                <div className='trends__item__sparkline'>
+                  <Sparklines width={50} height={28} data={hashtag.get('history').reverse().map(day => day.get('uses')).toArray()}>
+                    <SparklinesCurve style={{ fill: 'none' }} />
+                  </Sparklines>
+                </div>
+              </div>
+            ))}
+          </div>
+        </div>
+      );
+    }
+
     if (results.get('accounts') && results.get('accounts').size > 0) {
       count   += results.get('accounts').size;
       accounts = (
@@ -48,7 +100,7 @@ export default class SearchResults extends ImmutablePureComponent {
 
           {results.get('hashtags').map(hashtag => (
             <Link key={hashtag} className='search-results__hashtag' to={`/timelines/tag/${hashtag}`}>
-              #{hashtag}
+              {hashtag}
             </Link>
           ))}
         </div>
@@ -58,6 +110,7 @@ export default class SearchResults extends ImmutablePureComponent {
     return (
       <div className='search-results'>
         <div className='search-results__header'>
+          <i className='fa fa-search fa-fw' />
           <FormattedMessage id='search_results.total' defaultMessage='{count, number} {count, plural, one {result} other {results}}' values={{ count }} />
         </div>