Add support for emoji reactions

Squashed, modified, and rebased from glitch-soc/mastodon#2221.

Co-authored-by: fef <owo@fef.moe>
Co-authored-by: Jeremy Kescher <jeremy@kescher.at>
Co-authored-by: neatchee <neatchee@gmail.com>
Co-authored-by: Ivan Rodriguez <104603218+IRod22@users.noreply.github.com>
Co-authored-by: Plastikmensch <plastikmensch@users.noreply.github.com>

.env.production.sample

@@ -269,6 +269,9 @@ MAX_POLL_OPTIONS=5
 # Maximum allowed poll option characters
 MAX_POLL_OPTION_CHARS=100
 
+# Maximum number of emoji reactions per toot and user (minimum 1)
+MAX_REACTIONS=1
+
 # Maximum image and video/audio upload sizes
 # Units are in bytes
 # 1048576 bytes equals 1 megabyte

app/controllers/api/v1/statuses/reactions_controller.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+class Api::V1::Statuses::ReactionsController < Api::BaseController
+  include Authorization
+
+  before_action -> { doorkeeper_authorize! :write, :'write:favourites' }
+  before_action :require_user!
+  before_action :set_status
+
+  def create
+    ReactService.new.call(current_account, @status, params[:id])
+    render json: @status, serializer: REST::StatusSerializer
+  end
+
+  def destroy
+    UnreactWorker.perform_async(current_account.id, @status.id, params[:id])
+
+    render json: @status, serializer: REST::StatusSerializer, relationships: StatusRelationshipsPresenter.new([@status], current_account.id, reactions_map: { @status.id => false })
+  rescue Mastodon::NotPermittedError
+    not_found
+  end
+
+  private
+
+  def set_status
+    @status = Status.find(params[:status_id])
+    authorize @status, :show?
+  rescue Mastodon::NotPermittedError
+    not_found
+  end
+end

app/javascript/flavours/glitch/actions/interactions.js

@@ -51,6 +51,16 @@ export const UNBOOKMARK_REQUEST = 'UNBOOKMARKED_REQUEST';
 export const UNBOOKMARK_SUCCESS = 'UNBOOKMARKED_SUCCESS';
 export const UNBOOKMARK_FAIL    = 'UNBOOKMARKED_FAIL';
 
+export const REACTION_UPDATE = 'REACTION_UPDATE';
+
+export const REACTION_ADD_REQUEST = 'REACTION_ADD_REQUEST';
+export const REACTION_ADD_SUCCESS = 'REACTION_ADD_SUCCESS';
+export const REACTION_ADD_FAIL    = 'REACTION_ADD_FAIL';
+
+export const REACTION_REMOVE_REQUEST = 'REACTION_REMOVE_REQUEST';
+export const REACTION_REMOVE_SUCCESS = 'REACTION_REMOVE_SUCCESS';
+export const REACTION_REMOVE_FAIL    = 'REACTION_REMOVE_FAIL';
+
 export function reblog(status, visibility) {
   return function (dispatch, getState) {
     dispatch(reblogRequest(status));
@@ -516,3 +526,75 @@ export function unpinFail(status, error) {
     skipLoading: true,
   };
 }
+
+export const addReaction = (statusId, name, url) => (dispatch, getState) => {
+  const status = getState().get('statuses').get(statusId);
+  let alreadyAdded = false;
+  if (status) {
+    const reaction = status.get('reactions').find(x => x.get('name') === name);
+    if (reaction && reaction.get('me')) {
+      alreadyAdded = true;
+    }
+  }
+  if (!alreadyAdded) {
+    dispatch(addReactionRequest(statusId, name, url));
+  }
+
+  // encodeURIComponent is required for the Keycap Number Sign emoji, see:
+  // <https://github.com/glitch-soc/mastodon/pull/1980#issuecomment-1345538932>
+  api(getState).post(`/api/v1/statuses/${statusId}/react/${encodeURIComponent(name)}`).then(() => {
+    dispatch(addReactionSuccess(statusId, name));
+  }).catch(err => {
+    if (!alreadyAdded) {
+      dispatch(addReactionFail(statusId, name, err));
+    }
+  });
+};
+
+export const addReactionRequest = (statusId, name, url) => ({
+  type: REACTION_ADD_REQUEST,
+  id: statusId,
+  name,
+  url,
+});
+
+export const addReactionSuccess = (statusId, name) => ({
+  type: REACTION_ADD_SUCCESS,
+  id: statusId,
+  name,
+});
+
+export const addReactionFail = (statusId, name, error) => ({
+  type: REACTION_ADD_FAIL,
+  id: statusId,
+  name,
+  error,
+});
+
+export const removeReaction = (statusId, name) => (dispatch, getState) => {
+  dispatch(removeReactionRequest(statusId, name));
+
+  api(getState).post(`/api/v1/statuses/${statusId}/unreact/${encodeURIComponent(name)}`).then(() => {
+    dispatch(removeReactionSuccess(statusId, name));
+  }).catch(err => {
+    dispatch(removeReactionFail(statusId, name, err));
+  });
+};
+
+export const removeReactionRequest = (statusId, name) => ({
+  type: REACTION_REMOVE_REQUEST,
+  id: statusId,
+  name,
+});
+
+export const removeReactionSuccess = (statusId, name) => ({
+  type: REACTION_REMOVE_SUCCESS,
+  id: statusId,
+  name,
+});
+
+export const removeReactionFail = (statusId, name) => ({
+  type: REACTION_REMOVE_FAIL,
+  id: statusId,
+  name,
+});

app/javascript/flavours/glitch/actions/notifications.js

@@ -144,6 +144,7 @@ const excludeTypesFromFilter = filter => {
     'follow',
     'follow_request',
     'favourite',
+    'reaction',
     'reblog',
     'mention',
     'poll',

app/javascript/flavours/glitch/components/status.jsx

@@ -20,7 +20,7 @@ import Card from '../features/status/components/card';
 // to use the progress bar to show download progress
 import Bundle from '../features/ui/components/bundle';
 import { MediaGallery, Video, Audio } from '../features/ui/util/async-components';
-import { displayMedia } from '../initial_state';
+import { displayMedia, visibleReactions } from '../initial_state';
 
 import AttachmentList from './attachment_list';
 import { getHashtagBarForStatus } from './hashtag_bar';
@@ -29,6 +29,7 @@ import StatusContent from './status_content';
 import StatusHeader from './status_header';
 import StatusIcons from './status_icons';
 import StatusPrepend from './status_prepend';
+import StatusReactions from './status_reactions';
 
 const domParser = new DOMParser();
 
@@ -71,6 +72,10 @@ export const defaultMediaVisibility = (status, settings) => {
 
 class Status extends ImmutablePureComponent {
 
+  static contextTypes = {
+    identity: PropTypes.object,
+  };
+
   static propTypes = {
     containerId: PropTypes.string,
     id: PropTypes.string,
@@ -86,6 +91,8 @@ class Status extends ImmutablePureComponent {
     onDelete: PropTypes.func,
     onDirect: PropTypes.func,
     onMention: PropTypes.func,
+    onReactionAdd: PropTypes.func,
+    onReactionRemove: PropTypes.func,
     onPin: PropTypes.func,
     onOpenMedia: PropTypes.func,
     onOpenVideo: PropTypes.func,
@@ -751,6 +758,7 @@ class Status extends ImmutablePureComponent {
     if (this.props.prepend && account) {
       const notifKind = {
         favourite: 'favourited',
+        reaction: 'reacted',
         reblog: 'boosted',
         reblogged_by: 'boosted',
         status: 'posted',
@@ -837,6 +845,15 @@ class Status extends ImmutablePureComponent {
             {...statusContentProps}
           />
 
+          <StatusReactions
+            statusId={status.get('id')}
+            reactions={status.get('reactions')}
+            numVisible={visibleReactions}
+            addReaction={this.props.onReactionAdd}
+            removeReaction={this.props.onReactionRemove}
+            canReact={this.context.identity.signedIn}
+          />
+
           {!isCollapsed || !(muted || !settings.getIn(['collapsed', 'show_action_bar'])) ? (
             <StatusActionBar
               status={status}

app/javascript/flavours/glitch/components/status_action_bar.jsx

@@ -13,7 +13,8 @@ import { accountAdminLink, statusAdminLink } from 'flavours/glitch/utils/backend
 import { WithRouterPropTypes } from 'flavours/glitch/utils/react_router';
 
 import DropdownMenuContainer from '../containers/dropdown_menu_container';
-import { me } from '../initial_state';
+import EmojiPickerDropdown from '../features/compose/containers/emoji_picker_dropdown_container';
+import { me, maxReactions } from '../initial_state';
 
 import { IconButton } from './icon_button';
 import { RelativeTimestamp } from './relative_timestamp';
@@ -35,6 +36,7 @@ const messages = defineMessages({
   cancel_reblog_private: { id: 'status.cancel_reblog_private', defaultMessage: 'Unboost' },
   cannot_reblog: { id: 'status.cannot_reblog', defaultMessage: 'This post cannot be boosted' },
   favourite: { id: 'status.favourite', defaultMessage: 'Favorite' },
+  react: { id: 'status.react', defaultMessage: 'React' },
   bookmark: { id: 'status.bookmark', defaultMessage: 'Bookmark' },
   open: { id: 'status.open', defaultMessage: 'Expand this status' },
   report: { id: 'status.report', defaultMessage: 'Report @{name}' },
@@ -63,6 +65,7 @@ class StatusActionBar extends ImmutablePureComponent {
     status: ImmutablePropTypes.map.isRequired,
     onReply: PropTypes.func,
     onFavourite: PropTypes.func,
+    onReactionAdd: PropTypes.func,
     onReblog: PropTypes.func,
     onDelete: PropTypes.func,
     onDirect: PropTypes.func,
@@ -120,6 +123,10 @@ class StatusActionBar extends ImmutablePureComponent {
     }
   };
 
+  handleEmojiPick = data => {
+    this.props.onReactionAdd(this.props.status.get('id'), data.native.replace(/:/g, ''), data.imageUrl);
+  };
+
   handleReblogClick = e => {
     const { signedIn } = this.context.identity;
 
@@ -195,6 +202,8 @@ class StatusActionBar extends ImmutablePureComponent {
     this.props.onAddFilter(this.props.status);
   };
 
+  handleNoOp = () => {}; // hack for reaction add button
+
   render () {
     const { status, intl, withDismiss, withCounters, showReplyCount, scrollKey } = this.props;
     const { permissions, signedIn } = this.context.identity;
@@ -300,6 +309,17 @@ class StatusActionBar extends ImmutablePureComponent {
       <IconButton className='status__action-bar-button' title={intl.formatMessage(messages.hide)} icon='eye' onClick={this.handleHideClick} />
     );
 
+    const canReact = permissions && status.get('reactions').filter(r => r.get('count') > 0 && r.get('me')).size < maxReactions;
+    const reactButton = (
+      <IconButton
+        className='status__action-bar-button'
+        onClick={this.handleNoOp} // EmojiPickerDropdown handles that
+        title={intl.formatMessage(messages.react)}
+        disabled={!canReact}
+        icon='plus'
+      />
+    );
+
     return (
       <div className='status__action-bar'>
         <IconButton
@@ -312,6 +332,11 @@ class StatusActionBar extends ImmutablePureComponent {
         />
         <IconButton className={classNames('status__action-bar-button', { reblogPrivate })} disabled={!publicStatus && !reblogPrivate} active={status.get('reblogged')} title={reblogTitle} icon={reblogIcon} onClick={this.handleReblogClick} counter={withCounters ? status.get('reblogs_count') : undefined} />
         <IconButton className='status__action-bar-button star-icon' animate active={status.get('favourited')} title={intl.formatMessage(messages.favourite)} icon='star' onClick={this.handleFavouriteClick} counter={withCounters ? status.get('favourites_count') : undefined} />
+        {
+          permissions
+            ? <EmojiPickerDropdown className='status__action-bar-button' onPickEmoji={this.handleEmojiPick} button={reactButton} disabled={!canReact} />
+            : reactButton
+        }
         <IconButton className='status__action-bar-button bookmark-icon' disabled={!signedIn} active={status.get('bookmarked')} title={intl.formatMessage(messages.bookmark)} icon='bookmark' onClick={this.handleBookmarkClick} />
 
         {filterButton}

app/javascript/flavours/glitch/components/status_prepend.jsx

@@ -59,6 +59,14 @@ export default class StatusPrepend extends PureComponent {
           values={{ name : link }}
         />
       );
+    case 'reaction':
+      return (
+        <FormattedMessage
+          id='notification.reaction'
+          defaultMessage='{name} reacted to your status'
+          values={{ name: link }}
+        />
+      );
     case 'reblog':
       return (
         <FormattedMessage
@@ -113,6 +121,9 @@ export default class StatusPrepend extends PureComponent {
     case 'favourite':
       iconId = 'star';
       break;
+    case 'reaction':
+      iconId = 'plus';
+      break;
     case 'featured':
       iconId = 'thumb-tack';
       break;

app/javascript/flavours/glitch/components/status_reactions.jsx

@@ -0,0 +1,175 @@
+import PropTypes from 'prop-types';
+import React from 'react';
+
+import classNames from 'classnames';
+
+import ImmutablePropTypes from 'react-immutable-proptypes';
+import ImmutablePureComponent from 'react-immutable-pure-component';
+
+import TransitionMotion from 'react-motion/lib/TransitionMotion';
+import spring from 'react-motion/lib/spring';
+
+import { unicodeMapping } from '../features/emoji/emoji_unicode_mapping_light';
+import { autoPlayGif, reduceMotion } from '../initial_state';
+import { assetHost } from '../utils/config';
+
+import { AnimatedNumber } from './animated_number';
+
+export default class StatusReactions extends ImmutablePureComponent {
+
+  static propTypes = {
+    statusId: PropTypes.string.isRequired,
+    reactions: ImmutablePropTypes.list.isRequired,
+    numVisible: PropTypes.number,
+    addReaction: PropTypes.func.isRequired,
+    canReact: PropTypes.bool.isRequired,
+    removeReaction: PropTypes.func.isRequired,
+  };
+
+  willEnter() {
+    return { scale: reduceMotion ? 1 : 0 };
+  }
+
+  willLeave() {
+    return { scale: reduceMotion ? 0 : spring(0, { stiffness: 170, damping: 26 }) };
+  }
+
+  render() {
+    const { reactions, numVisible } = this.props;
+    let visibleReactions = reactions
+      .filter(x => x.get('count') > 0)
+      .sort((a, b) => b.get('count') - a.get('count'));
+
+    if (numVisible >= 0) {
+      visibleReactions = visibleReactions.filter((_, i) => i < numVisible);
+    }
+
+    const styles = visibleReactions.map(reaction => ({
+      key: reaction.get('name'),
+      data: reaction,
+      style: { scale: reduceMotion ? 1 : spring(1, { stiffness: 150, damping: 13 }) },
+    })).toArray();
+
+    return (
+      <TransitionMotion styles={styles} willEnter={this.willEnter} willLeave={this.willLeave}>
+        {items => (
+          <div className={classNames('reactions-bar', { 'reactions-bar--empty': visibleReactions.isEmpty() })}>
+            {items.map(({ key, data, style }) => (
+              <Reaction
+                key={key}
+                statusId={this.props.statusId}
+                reaction={data}
+                style={{ transform: `scale(${style.scale})`, position: style.scale < 0.5 ? 'absolute' : 'static' }}
+                addReaction={this.props.addReaction}
+                removeReaction={this.props.removeReaction}
+                canReact={this.props.canReact}
+              />
+            ))}
+          </div>
+        )}
+      </TransitionMotion>
+    );
+  }
+
+}
+
+class Reaction extends ImmutablePureComponent {
+
+  static propTypes = {
+    statusId: PropTypes.string,
+    reaction: ImmutablePropTypes.map.isRequired,
+    addReaction: PropTypes.func.isRequired,
+    removeReaction: PropTypes.func.isRequired,
+    canReact: PropTypes.bool.isRequired,
+    style: PropTypes.object,
+  };
+
+  state = {
+    hovered: false,
+  };
+
+  handleClick = () => {
+    const { reaction, statusId, addReaction, removeReaction } = this.props;
+
+    if (reaction.get('me')) {
+      removeReaction(statusId, reaction.get('name'));
+    } else {
+      addReaction(statusId, reaction.get('name'));
+    }
+  }
+
+  handleMouseEnter = () => this.setState({ hovered: true })
+
+  handleMouseLeave = () => this.setState({ hovered: false })
+
+  render() {
+    const { reaction } = this.props;
+
+    return (
+      <button
+        className={classNames('reactions-bar__item', { active: reaction.get('me') })}
+        onClick={this.handleClick}
+        onMouseEnter={this.handleMouseEnter}
+        onMouseLeave={this.handleMouseLeave}
+        disabled={!this.props.canReact}
+        style={this.props.style}
+      >
+        <span className='reactions-bar__item__emoji'>
+          <Emoji
+            hovered={this.state.hovered}
+            emoji={reaction.get('name')}
+            url={reaction.get('url')}
+            staticUrl={reaction.get('static_url')}
+          />
+        </span>
+        <span className='reactions-bar__item__count'>
+          <AnimatedNumber value={reaction.get('count')} />
+        </span>
+      </button>
+    );
+  }
+
+}
+
+class Emoji extends React.PureComponent {
+
+  static propTypes = {
+    emoji: PropTypes.string.isRequired,
+    hovered: PropTypes.bool.isRequired,
+    url: PropTypes.string,
+    staticUrl: PropTypes.string,
+  };
+
+  render() {
+    const { emoji, hovered, url, staticUrl } = this.props;
+
+    if (unicodeMapping[emoji]) {
+      const { filename, shortCode } = unicodeMapping[this.props.emoji];
+      const title = shortCode ? `:${shortCode}:` : '';
+
+      return (
+        <img
+          draggable='false'
+          className='emojione'
+          alt={emoji}
+          title={title}
+          src={`${assetHost}/emoji/${filename}.svg`}
+        />
+      );
+    } else {
+      const filename = (autoPlayGif || hovered) ? url : staticUrl;
+      const shortCode = `:${emoji}:`;
+
+      return (
+        <img
+          draggable='false'
+          className='emojione custom-emoji'
+          alt={shortCode}
+          title={shortCode}
+          src={filename}
+        />
+      );
+    }
+  }
+
+}

app/javascript/flavours/glitch/containers/status_container.js

@@ -21,6 +21,8 @@ import {
   unbookmark,
   pin,
   unpin,
+  addReaction,
+  removeReaction,
 } from 'flavours/glitch/actions/interactions';
 import { changeLocalSetting } from 'flavours/glitch/actions/local_settings';
 import { openModal } from 'flavours/glitch/actions/modal';
@@ -173,6 +175,14 @@ const mapDispatchToProps = (dispatch, { intl, contextType }) => ({
     }
   },
 
+  onReactionAdd (statusId, name, url) {
+    dispatch(addReaction(statusId, name, url));
+  },
+
+  onReactionRemove (statusId, name) {
+    dispatch(removeReaction(statusId, name));
+  },
+
   onEmbed (status) {
     dispatch(openModal({
       modalType: 'EMBED',

app/javascript/flavours/glitch/features/compose/components/emoji_picker_dropdown.jsx

@@ -324,6 +324,7 @@ class EmojiPickerDropdown extends PureComponent {
     onSkinTone: PropTypes.func.isRequired,
     skinTone: PropTypes.number.isRequired,
     button: PropTypes.node,
+    disabled: PropTypes.bool,
   };
 
   state = {
@@ -357,7 +358,7 @@ class EmojiPickerDropdown extends PureComponent {
   };
 
   onToggle = (e) => {
-    if (!this.state.loading && (!e.key || e.key === 'Enter')) {
+    if (!this.state.disabled && !this.state.loading && (!e.key || e.key === 'Enter')) {
       if (this.state.active) {
         this.onHideDropdown();
       } else {
@@ -395,7 +396,7 @@ class EmojiPickerDropdown extends PureComponent {
           />}
         </div>
 
-        <Overlay show={active} placement={'bottom'} target={this.findTarget} popperConfig={{ strategy: 'fixed' }}>
+        <Overlay show={active} placement={'bottom'} flip target={this.findTarget} popperConfig={{ strategy: 'fixed' }}>
           {({ props, placement })=> (
             <div {...props} style={{ ...props.style, width: 299 }}>
               <div className={`dropdown-animation ${placement}`}>

app/javascript/flavours/glitch/features/notifications/components/filter_bar.jsx

@@ -8,6 +8,7 @@ import { Icon }  from 'flavours/glitch/components/icon';
 const tooltips = defineMessages({
   mentions: { id: 'notifications.filter.mentions', defaultMessage: 'Mentions' },
   favourites: { id: 'notifications.filter.favourites', defaultMessage: 'Favorites' },
+  reactions: { id: 'notifications.filter.reactions', defaultMessage: 'Reactions' },
   boosts: { id: 'notifications.filter.boosts', defaultMessage: 'Boosts' },
   polls: { id: 'notifications.filter.polls', defaultMessage: 'Poll results' },
   follows: { id: 'notifications.filter.follows', defaultMessage: 'Follows' },
@@ -75,6 +76,13 @@ class FilterBar extends PureComponent {
         >
           <Icon id='star' fixedWidth />
         </button>
+        <button
+          className={selectedFilter === 'reaction' ? 'active' : ''}
+          onClick={this.onClick('reaction')}
+          title={intl.formatMessage(tooltips.reactions)}
+        >
+          <Icon id='plus' fixedWidth />
+        </button>
         <button
           className={selectedFilter === 'reblog' ? 'active' : ''}
           onClick={this.onClick('reblog')}

app/javascript/flavours/glitch/features/notifications/components/notification.jsx

@@ -159,6 +159,28 @@ export default class Notification extends ImmutablePureComponent {
           unread={this.props.unread}
         />
       );
+    case 'reaction':
+      return (
+        <StatusContainer
+          containerId={notification.get('id')}
+          hidden={hidden}
+          id={notification.get('status')}
+          account={notification.get('account')}
+          prepend='reaction'
+          muted
+          notification={notification}
+          onMoveDown={onMoveDown}
+          onMoveUp={onMoveUp}
+          onMention={onMention}
+          getScrollPosition={getScrollPosition}
+          updateScrollBottom={updateScrollBottom}
+          cachedMediaWidth={this.props.cachedMediaWidth}
+          cacheMediaWidth={this.props.cacheMediaWidth}
+          onUnmount={this.props.onUnmount}
+          withDismiss
+          unread={this.props.unread}
+        />
+      );
     case 'reblog':
       return (
         <StatusContainer

app/javascript/flavours/glitch/features/status/components/action_bar.jsx

@@ -14,7 +14,8 @@ import { WithRouterPropTypes } from 'flavours/glitch/utils/react_router';
 
 import { IconButton } from '../../../components/icon_button';
 import DropdownMenuContainer from '../../../containers/dropdown_menu_container';
-import { me } from '../../../initial_state';
+import { me, maxReactions } from '../../../initial_state';
+import EmojiPickerDropdown from '../../compose/containers/emoji_picker_dropdown_container';
 
 const messages = defineMessages({
   delete: { id: 'status.delete', defaultMessage: 'Delete' },
@@ -28,6 +29,7 @@ const messages = defineMessages({
   cancel_reblog_private: { id: 'status.cancel_reblog_private', defaultMessage: 'Unboost' },
   cannot_reblog: { id: 'status.cannot_reblog', defaultMessage: 'This post cannot be boosted' },
   favourite: { id: 'status.favourite', defaultMessage: 'Favorite' },
+  react: { id: 'status.react', defaultMessage: 'React' },
   bookmark: { id: 'status.bookmark', defaultMessage: 'Bookmark' },
   more: { id: 'status.more', defaultMessage: 'More' },
   mute: { id: 'status.mute', defaultMessage: 'Mute @{name}' },
@@ -57,6 +59,7 @@ class ActionBar extends PureComponent {
     onReply: PropTypes.func.isRequired,
     onReblog: PropTypes.func.isRequired,
     onFavourite: PropTypes.func.isRequired,
+    onReactionAdd: PropTypes.func.isRequired,
     onBookmark: PropTypes.func.isRequired,
     onMute: PropTypes.func,
     onMuteConversation: PropTypes.func,
@@ -84,6 +87,10 @@ class ActionBar extends PureComponent {
     this.props.onFavourite(this.props.status, e);
   };
 
+  handleEmojiPick = data => {
+    this.props.onReactionAdd(this.props.status.get('id'), data.native.replace(/:/g, ''), data.imageUrl);
+  };
+
   handleBookmarkClick = (e) => {
     this.props.onBookmark(this.props.status, e);
   };
@@ -143,6 +150,8 @@ class ActionBar extends PureComponent {
     navigator.clipboard.writeText(url);
   };
 
+  handleNoOp = () => {}; // hack for reaction add button
+
   render () {
     const { status, intl } = this.props;
     const { signedIn, permissions } = this.context.identity;
@@ -208,6 +217,17 @@ class ActionBar extends PureComponent {
       }
     }
 
+    const canReact = signedIn && status.get('reactions').filter(r => r.get('count') > 0 && r.get('me')).size < maxReactions;
+    const reactButton = (
+      <IconButton
+        className='plus-icon'
+        onClick={this.handleNoOp} // EmojiPickerDropdown handles that
+        title={intl.formatMessage(messages.react)}
+        disabled={!canReact}
+        icon='plus'
+      />
+    );
+
     const reblogPrivate = status.getIn(['account', 'id']) === me && status.get('visibility') === 'private';
 
     let reblogTitle;
@@ -226,6 +246,13 @@ class ActionBar extends PureComponent {
         <div className='detailed-status__button'><IconButton title={intl.formatMessage(messages.reply)} icon={status.get('in_reply_to_id', null) === null ? 'reply' : 'reply-all'} onClick={this.handleReplyClick} /></div>
         <div className='detailed-status__button'><IconButton className={classNames({ reblogPrivate })} disabled={!publicStatus && !reblogPrivate} active={status.get('reblogged')} title={reblogTitle} icon='retweet' onClick={this.handleReblogClick} /></div>
         <div className='detailed-status__button'><IconButton className='star-icon' animate active={status.get('favourited')} title={intl.formatMessage(messages.favourite)} icon='star' onClick={this.handleFavouriteClick} /></div>
+        <div className='detailed-status__button'>
+          {
+            signedIn
+              ? <EmojiPickerDropdown onPickEmoji={this.handleEmojiPick} button={reactButton} disabled={!canReact} />
+              : reactButton
+          }
+        </div>
         <div className='detailed-status__button'><IconButton className='bookmark-icon' disabled={!signedIn} active={status.get('bookmarked')} title={intl.formatMessage(messages.bookmark)} icon='bookmark' onClick={this.handleBookmarkClick} /></div>
 
         <div className='detailed-status__action-bar-dropdown'>

app/javascript/flavours/glitch/features/status/components/detailed_status.jsx

@@ -22,6 +22,7 @@ import { Avatar } from '../../../components/avatar';
 import { DisplayName } from '../../../components/display_name';
 import MediaGallery from '../../../components/media_gallery';
 import StatusContent from '../../../components/status_content';
+import StatusReactions from '../../../components/status_reactions';
 import Audio from '../../audio';
 import scheduleIdleTask from '../../ui/util/schedule_idle_task';
 import Video from '../../video';
@@ -30,6 +31,10 @@ import Card from './card';
 
 class DetailedStatus extends ImmutablePureComponent {
 
+  static contextTypes = {
+    identity: PropTypes.object,
+  };
+
   static propTypes = {
     status: ImmutablePropTypes.map,
     settings: ImmutablePropTypes.map.isRequired,
@@ -48,6 +53,8 @@ class DetailedStatus extends ImmutablePureComponent {
       available: PropTypes.bool,
     }),
     onToggleMediaVisibility: PropTypes.func,
+    onReactionAdd: PropTypes.func.isRequired,
+    onReactionRemove: PropTypes.func.isRequired,
     intl: PropTypes.object.isRequired,
     ...WithRouterPropTypes,
   };
@@ -332,6 +339,14 @@ class DetailedStatus extends ImmutablePureComponent {
             {...statusContentProps}
           />
 
+          <StatusReactions
+            statusId={status.get('id')}
+            reactions={status.get('reactions')}
+            addReaction={this.props.onReactionAdd}
+            removeReaction={this.props.onReactionRemove}
+            canReact={this.context.identity.signedIn}
+          />
+
           <div className='detailed-status__meta'>
             <a className='detailed-status__datetime' href={status.get('url')} target='_blank' rel='noopener noreferrer'>
               <FormattedDate value={new Date(status.get('created_at'))} hour12={false} year='numeric' month='short' day='2-digit' hour='2-digit' minute='2-digit' />

app/javascript/flavours/glitch/features/status/index.jsx

@@ -37,6 +37,8 @@ import {
   unreblog,
   pin,
   unpin,
+  addReaction,
+  removeReaction,
 } from '../../actions/interactions';
 import { changeLocalSetting } from '../../actions/local_settings';
 import { openModal } from '../../actions/modal';
@@ -305,6 +307,19 @@ class Status extends ImmutablePureComponent {
     }
   };
 
+  handleReactionAdd = (statusId, name, url) => {
+    const { dispatch } = this.props;
+    const { signedIn } = this.context.identity;
+
+    if (signedIn) {
+      dispatch(addReaction(statusId, name, url));
+    }
+  };
+
+  handleReactionRemove = (statusId, name) => {
+    this.props.dispatch(removeReaction(statusId, name));
+  };
+
   handlePin = (status) => {
     if (status.get('pinned')) {
       this.props.dispatch(unpin(status));
@@ -741,6 +756,8 @@ class Status extends ImmutablePureComponent {
                   settings={settings}
                   onOpenVideo={this.handleOpenVideo}
                   onOpenMedia={this.handleOpenMedia}
+                  onReactionAdd={this.handleReactionAdd}
+                  onReactionRemove={this.handleReactionRemove}
                   expanded={isExpanded}
                   onToggleHidden={this.handleToggleHidden}
                   onTranslate={this.handleTranslate}
@@ -755,6 +772,7 @@ class Status extends ImmutablePureComponent {
                   status={status}
                   onReply={this.handleReplyClick}
                   onFavourite={this.handleFavouriteClick}
+                  onReactionAdd={this.handleReactionAdd}
                   onReblog={this.handleReblogClick}
                   onBookmark={this.handleBookmarkClick}
                   onDelete={this.handleDeleteClick}

app/javascript/flavours/glitch/initial_state.js

@@ -62,6 +62,7 @@
  * @property {boolean} limited_federation_mode
  * @property {string} locale
  * @property {string | null} mascot
+ * @property {number} max_reactions
  * @property {string=} me
  * @property {string=} moved_to_account_id
  * @property {string=} owner
@@ -82,6 +83,7 @@
  * @property {boolean} use_blurhash
  * @property {boolean=} use_pending_items
  * @property {string} version
+ * @property {number} visible_reactions
  * @property {string} sso_redirect
  * @property {boolean} translation_enabled
  * @property {string} status_page_url
@@ -106,6 +108,7 @@ export const hasMultiColumnPath = initialPath === '/'
  * @property {object} local_settings
  * @property {number} max_toot_chars
  * @property {number} poll_limits
+ * @property {number} max_reactions
  */
 
 const element = document.getElementById('initial-state');
@@ -142,6 +145,7 @@ export const expandSpoilers = getMeta('expand_spoilers');
 export const forceSingleColumn = !getMeta('advanced_layout');
 export const limitedFederationMode = getMeta('limited_federation_mode');
 export const mascot = getMeta('mascot');
+export const maxReactions = (initialState && initialState.max_reactions) || 1;
 export const me = getMeta('me');
 export const movedToAccountId = getMeta('moved_to_account_id');
 export const owner = getMeta('owner');
@@ -161,6 +165,7 @@ export const unfollowModal = getMeta('unfollow_modal');
 export const useBlurhash = getMeta('use_blurhash');
 export const usePendingItems = getMeta('use_pending_items');
 export const version = getMeta('version');
+export const visibleReactions = getMeta('visible_reactions');
 export const languages = initialState?.languages;
 export const criticalUpdatesPending = initialState?.critical_updates_pending;
 export const statusPageUrl = getMeta('status_page_url');

app/javascript/flavours/glitch/locales/en.json

@@ -71,11 +71,14 @@
   "navigation_bar.keyboard_shortcuts": "Keyboard shortcuts",
   "navigation_bar.misc": "Misc",
   "notification.markForDeletion": "Mark for deletion",
+  "notification.reaction": "{name} reacted to your post",
   "notification_purge.btn_all": "Select\nall",
   "notification_purge.btn_apply": "Clear\nselected",
   "notification_purge.btn_invert": "Invert\nselection",
   "notification_purge.btn_none": "Select\nnone",
   "notification_purge.start": "Enter notification cleaning mode",
+  "notifications.column_settings.reaction": "Reactions:",
+  "notifications.filter.reactions": "Reactions",
   "notifications.marked_clear": "Clear selected notifications",
   "notifications.marked_clear_confirmation": "Are you sure you want to permanently clear all selected notifications?",
   "onboarding.done": "Done",
@@ -185,8 +188,10 @@
   "status.in_reply_to": "This toot is a reply",
   "status.is_poll": "This toot is a poll",
   "status.local_only": "Only visible from your instance",
+  "status.react": "React",
   "status.sensitive_toggle": "Click to view",
   "status.uncollapse": "Uncollapse",
+  "tooltips.reactions": "Reactions",
   "web_app_crash.change_your_settings": "Change your {settings}",
   "web_app_crash.content": "You could try any of the following:",
   "web_app_crash.debug_info": "Debug information",

app/javascript/flavours/glitch/reducers/settings.js

@@ -38,6 +38,7 @@ const initialState = ImmutableMap({
       follow: false,
       follow_request: false,
       favourite: false,
+      reaction: false,
       reblog: false,
       mention: false,
       poll: false,
@@ -60,6 +61,7 @@ const initialState = ImmutableMap({
       follow: true,
       follow_request: false,
       favourite: true,
+      reaction: true,
       reblog: true,
       mention: true,
       poll: true,
@@ -73,6 +75,7 @@ const initialState = ImmutableMap({
       follow: true,
       follow_request: false,
       favourite: true,
+      reaction: true,
       reblog: true,
       mention: true,
       poll: true,

app/javascript/flavours/glitch/reducers/statuses.js

@@ -15,6 +15,11 @@ import {
   BOOKMARK_FAIL,
   UNBOOKMARK_REQUEST,
   UNBOOKMARK_FAIL,
+  REACTION_UPDATE,
+  REACTION_ADD_FAIL,
+  REACTION_REMOVE_FAIL,
+  REACTION_ADD_REQUEST,
+  REACTION_REMOVE_REQUEST,
 } from '../actions/interactions';
 import {
   STATUS_MUTE_SUCCESS,
@@ -42,6 +47,43 @@ const deleteStatus = (state, id, references) => {
   return state.delete(id);
 };
 
+const updateReaction = (state, id, name, updater) => state.update(
+  id,
+  status => status.update(
+    'reactions',
+    reactions => {
+      const index = reactions.findIndex(reaction => reaction.get('name') === name);
+      if (index > -1) {
+        return reactions.update(index, reaction => updater(reaction));
+      } else {
+        return reactions.push(updater(fromJS({ name, count: 0 })));
+      }
+    },
+  ),
+);
+
+const updateReactionCount = (state, reaction) => updateReaction(state, reaction.status_id, reaction.name, x => x.set('count', reaction.count));
+
+// The url parameter is only used when adding a new custom emoji reaction
+// (one that wasn't in the reactions list before) because we don't have its
+// URL yet.  In all other cases, it's undefined.
+const addReaction = (state, id, name, url) => updateReaction(
+  state,
+  id,
+  name,
+  x => x.set('me', true)
+    .update('count', n => n + 1)
+    .update('url', old => old ? old : url)
+    .update('static_url', old => old ? old : url),
+);
+
+const removeReaction = (state, id, name) => updateReaction(
+  state,
+  id,
+  name,
+  x => x.set('me', false).update('count', n => n - 1),
+);
+
 const statusTranslateSuccess = (state, id, translation) => {
   return state.withMutations(map => {
     map.setIn([id, 'translation'], fromJS(normalizeStatusTranslation(translation, map.get(id))));
@@ -95,6 +137,14 @@ export default function statuses(state = initialState, action) {
     return state.setIn([action.status.get('id'), 'reblogged'], true);
   case REBLOG_FAIL:
     return state.get(action.status.get('id')) === undefined ? state : state.setIn([action.status.get('id'), 'reblogged'], false);
+  case REACTION_UPDATE:
+    return updateReactionCount(state, action.reaction);
+  case REACTION_ADD_REQUEST:
+  case REACTION_REMOVE_FAIL:
+    return addReaction(state, action.id, action.name, action.url);
+  case REACTION_REMOVE_REQUEST:
+  case REACTION_ADD_FAIL:
+    return removeReaction(state, action.id, action.name);
   case UNREBLOG_REQUEST:
     return state.setIn([action.status.get('id'), 'reblogged'], false);
   case UNREBLOG_FAIL:

app/javascript/flavours/glitch/styles/components/accounts.scss

@@ -315,6 +315,10 @@
   text-align: center;
 }
 
+.detailed-status__button .emoji-button {
+  padding: 0;
+}
+
 .relationship-tag {
   color: $white;
   margin-bottom: 4px;

app/javascript/flavours/glitch/styles/components/status.scss

@@ -379,6 +379,10 @@
   .notification__message {
     margin: -10px 0 10px;
   }
+
+  .reactions-bar--empty {
+    display: none;
+  }
 }
 
 .notification-favourite {
@@ -523,6 +527,10 @@
   align-items: center;
   display: flex;
   margin-top: 8px;
+
+  & > .emoji-picker-dropdown > .emoji-button {
+    padding: 0;
+  }
 }
 
 .status__action-bar-button {
@@ -531,6 +539,10 @@
   &.icon-button--with-counter {
     margin-inline-end: 14px;
   }
+
+  .fa-plus {
+    padding-top: 1px;
+  }
 }
 
 .status__action-bar-dropdown {
@@ -598,6 +610,10 @@
   display: flex;
   flex-direction: row;
   padding: 10px 0;
+
+  .fa-plus {
+    padding-top: 2px;
+  }
 }
 
 .detailed-status__link {
@@ -1035,7 +1051,8 @@ a.status-card.compact:hover {
     border-bottom: 0;
 
     .status__content,
-    .status__action-bar {
+    .status__action-bar,
+    .reactions-bar {
       margin-inline-start: 46px + 10px;
       width: calc(100% - (46px + 10px));
     }

app/javascript/mastodon/locales/en.json

@@ -430,6 +430,7 @@
   "notification.mention": "{name} mentioned you",
   "notification.own_poll": "Your poll has ended",
   "notification.poll": "A poll you have voted in has ended",
+  "notification.reaction": "{name} reacted to your post",
   "notification.reblog": "{name} boosted your post",
   "notification.status": "{name} just posted",
   "notification.update": "{name} edited a post",
@@ -447,6 +448,7 @@
   "notifications.column_settings.mention": "Mentions:",
   "notifications.column_settings.poll": "Poll results:",
   "notifications.column_settings.push": "Push notifications",
+  "notifications.column_settings.reaction": "Reactions:",
   "notifications.column_settings.reblog": "Boosts:",
   "notifications.column_settings.show": "Show in column",
   "notifications.column_settings.sound": "Play sound",
@@ -648,6 +650,7 @@
   "status.pin": "Pin on profile",
   "status.pinned": "Pinned post",
   "status.read_more": "Read more",
+  "status.react": "React",
   "status.reblog": "Boost",
   "status.reblog_private": "Boost with original visibility",
   "status.reblogged_by": "{name} boosted",
@@ -686,6 +689,7 @@
   "timeline_hint.resources.followers": "Followers",
   "timeline_hint.resources.follows": "Follows",
   "timeline_hint.resources.statuses": "Older posts",
+  "tooltips.reactions": "Reactions",
   "trends.counter_by_accounts": "{count, plural, one {{counter} person} other {{counter} people}} in the past {days, plural, one {day} other {{days} days}}",
   "trends.trending_now": "Trending now",
   "ui.beforeunload": "Your draft will be lost if you leave Mastodon.",

app/javascript/mastodon/reducers/settings.js

@@ -56,6 +56,7 @@ const initialState = ImmutableMap({
       follow: true,
       follow_request: false,
       favourite: true,
+      reaction: true,
       reblog: true,
       mention: true,
       poll: true,
@@ -69,6 +70,7 @@ const initialState = ImmutableMap({
       follow: true,
       follow_request: false,
       favourite: true,
+      reaction: true,
       reblog: true,
       mention: true,
       poll: true,

app/lib/activitypub/activity.rb

@@ -39,6 +39,8 @@ class ActivityPub::Activity
         ActivityPub::Activity::Follow
       when 'Like'
         ActivityPub::Activity::Like
+      when 'EmojiReact'
+        ActivityPub::Activity::EmojiReact
       when 'Block'
         ActivityPub::Activity::Block
       when 'Update'
@@ -176,4 +178,32 @@ class ActivityPub::Activity
     Rails.logger.info("Rejected #{@json['type']} activity #{@json['id']} from #{@account.uri}#{@options[:relayed_through_actor] && "via #{@options[:relayed_through_actor].uri}"}")
     nil
   end
+
+  # Ensure emoji declared in the activity's tags are
+  # present in the database and downloaded to the local cache.
+  # Required by EmojiReact and Like for emoji reactions.
+  def process_emoji_tags(name, tags)
+    tag = as_array(tags).find { |item| item['type'] == 'Emoji' }
+    return if tag.nil?
+
+    custom_emoji_parser = ActivityPub::Parser::CustomEmojiParser.new(tag)
+    return if custom_emoji_parser.shortcode.blank? || custom_emoji_parser.image_remote_url.blank? || !name.eql?(custom_emoji_parser.shortcode)
+
+    emoji = CustomEmoji.find_by(shortcode: custom_emoji_parser.shortcode, domain: @account.domain)
+    return emoji unless emoji.nil? ||
+                        custom_emoji_parser.image_remote_url != emoji.image_remote_url ||
+                        (custom_emoji_parser.updated_at && custom_emoji_parser.updated_at >= emoji.updated_at)
+
+    begin
+      emoji ||= CustomEmoji.new(domain: @account.domain,
+                                shortcode: custom_emoji_parser.shortcode,
+                                uri: custom_emoji_parser.uri)
+      emoji.image_remote_url = custom_emoji_parser.image_remote_url
+      emoji.save
+    rescue Seahorse::Client::NetworkingError => e
+      Rails.logger.warn "Error fetching emoji: #{e}"
+      return
+    end
+    emoji
+  end
 end

app/lib/activitypub/activity/emoji_react.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+class ActivityPub::Activity::EmojiReact < ActivityPub::Activity
+  def perform
+    original_status = status_from_uri(object_uri)
+    name = @json['content']
+    return if original_status.nil? ||
+              !original_status.account.local? ||
+              delete_arrived_first?(@json['id'])
+
+    if /^:.*:$/.match?(name)
+      name.delete! ':'
+      custom_emoji = process_emoji_tags(name, @json['tag'])
+
+      return if custom_emoji.nil?
+    end
+
+    return if @account.reacted?(original_status, name, custom_emoji)
+
+    reaction = original_status.status_reactions.create!(account: @account, name: name, custom_emoji: custom_emoji)
+
+    LocalNotificationWorker.perform_async(original_status.account_id, reaction.id, 'StatusReaction', 'reaction')
+  rescue ActiveRecord::RecordInvalid
+    nil
+  end
+end

app/lib/activitypub/activity/like.rb

@@ -3,12 +3,38 @@
 class ActivityPub::Activity::Like < ActivityPub::Activity
   def perform
     original_status = status_from_uri(object_uri)
+    return if original_status.nil? || !original_status.account.local? || delete_arrived_first?(@json['id'])
 
-    return if original_status.nil? || !original_status.account.local? || delete_arrived_first?(@json['id']) || @account.favourited?(original_status)
+    return if maybe_process_misskey_reaction
+
+    return if @account.favourited?(original_status)
 
     favourite = original_status.favourites.create!(account: @account)
 
     LocalNotificationWorker.perform_async(original_status.account_id, favourite.id, 'Favourite', 'favourite')
     Trends.statuses.register(original_status)
   end
+
+  # Misskey delivers reactions as likes with the emoji in _misskey_reaction
+  # see https://misskey-hub.net/ns.html#misskey-reaction for details
+  def maybe_process_misskey_reaction
+    original_status = status_from_uri(object_uri)
+    name = @json['_misskey_reaction']
+    return false if name.nil?
+
+    if /^:.*:$/.match?(name)
+      name.delete! ':'
+      custom_emoji = process_emoji_tags(name, @json['tag'])
+
+      return false if custom_emoji.nil? # invalid custom emoji, treat it as a regular like
+    end
+    return true if @account.reacted?(original_status, name, custom_emoji)
+
+    reaction = original_status.status_reactions.create!(account: @account, name: name, custom_emoji: custom_emoji)
+    LocalNotificationWorker.perform_async(original_status.account_id, reaction.id, 'StatusReaction', 'reaction')
+    true
+  # account tried to react with disabled custom emoji. Returning true to discard activity.
+  rescue ActiveRecord::RecordInvalid
+    true
+  end
 end

app/lib/activitypub/activity/undo.rb

@@ -11,6 +11,8 @@ class ActivityPub::Activity::Undo < ActivityPub::Activity
       undo_follow
     when 'Like'
       undo_like
+    when 'EmojiReact'
+      undo_emoji_react
     when 'Block'
       undo_block
     when nil
@@ -108,6 +110,31 @@ class ActivityPub::Activity::Undo < ActivityPub::Activity
     if @account.favourited?(status)
       favourite = status.favourites.where(account: @account).first
       favourite&.destroy
+    elsif @object['_misskey_reaction'].present?
+      undo_emoji_react
+    else
+      delete_later!(object_uri)
+    end
+  end
+
+  def undo_emoji_react
+    name = @object['content'] || @object['_misskey_reaction']
+    return if name.nil?
+
+    status = status_from_uri(target_uri)
+
+    return if status.nil? || !status.account.local?
+
+    if /^:.*:$/.match?(name)
+      name.delete! ':'
+      custom_emoji = process_emoji_tags(name, @object['tag'])
+
+      return if custom_emoji.nil?
+    end
+
+    if @account.reacted?(status, name, custom_emoji)
+      reaction = status.status_reactions.where(account: @account, name: name).first
+      reaction&.destroy
     else
       delete_later!(object_uri)
     end

app/models/concerns/account_associations.rb

@@ -13,6 +13,7 @@ module AccountAssociations
     # Timelines
     has_many :statuses, inverse_of: :account, dependent: :destroy
     has_many :favourites, inverse_of: :account, dependent: :destroy
+    has_many :status_reactions, inverse_of: :account, dependent: :destroy
     has_many :bookmarks, inverse_of: :account, dependent: :destroy
     has_many :mentions, inverse_of: :account, dependent: :destroy
     has_many :notifications, inverse_of: :account, dependent: :destroy

app/models/concerns/account_interactions.rb

@@ -243,6 +243,10 @@ module AccountInteractions
     status.proper.favourites.where(account: self).exists?
   end
 
+  def reacted?(status, name, custom_emoji = nil)
+    status.proper.status_reactions.where(account: self, name: name, custom_emoji: custom_emoji).exists?
+  end
+
   def bookmarked?(status)
     status.proper.bookmarks.where(account: self).exists?
   end

app/models/concerns/has_user_settings.rb

@@ -123,6 +123,10 @@ module HasUserSettings
     settings['hide_followers_count']
   end
 
+  def setting_visible_reactions
+    integer_cast_setting('visible_reactions', 0)
+  end
+
   def allows_report_emails?
     settings['notification_emails.report']
   end
@@ -166,4 +170,14 @@ module HasUserSettings
   def hide_all_media?
     settings['web.display_media'] == 'hide_all'
   end
+
+  def integer_cast_setting(key, min = nil, max = nil)
+    i = ActiveModel::Type::Integer.new.cast(settings[key])
+    # the cast above doesn't return a number if passed the string "e"
+    i = 0 unless i.is_a? Numeric
+    return min if !min.nil? && i < min
+    return max if !max.nil? && i > max
+
+    i
+  end
 end

app/models/notification.rb

@@ -25,6 +25,7 @@ class Notification < ApplicationRecord
     'Follow' => :follow,
     'FollowRequest' => :follow_request,
     'Favourite' => :favourite,
+    'StatusReaction' => :reaction,
     'Poll' => :poll,
   }.freeze
 
@@ -35,6 +36,7 @@ class Notification < ApplicationRecord
     follow
     follow_request
     favourite
+    reaction
     poll
     update
     admin.sign_up
@@ -46,6 +48,7 @@ class Notification < ApplicationRecord
     reblog: [status: :reblog],
     mention: [mention: :status],
     favourite: [favourite: :status],
+    reaction: [status_reaction: :status],
     poll: [poll: :status],
     update: :status,
     'admin.report': [report: :target_account],
@@ -61,6 +64,7 @@ class Notification < ApplicationRecord
     belongs_to :follow, inverse_of: :notification
     belongs_to :follow_request, inverse_of: :notification
     belongs_to :favourite, inverse_of: :notification
+    belongs_to :status_reaction, inverse_of: :notification
     belongs_to :poll, inverse_of: false
     belongs_to :report, inverse_of: false
   end
@@ -81,6 +85,8 @@ class Notification < ApplicationRecord
       status&.reblog
     when :favourite
       favourite&.status
+    when :reaction
+      status_reaction&.status
     when :mention
       mention&.status
     when :poll
@@ -141,6 +147,8 @@ class Notification < ApplicationRecord
     end
   end
 
+  alias reaction status_reaction
+
   after_initialize :set_from_account
   before_validation :set_from_account
 
@@ -150,7 +158,7 @@ class Notification < ApplicationRecord
     return unless new_record?
 
     case activity_type
-    when 'Status', 'Follow', 'Favourite', 'FollowRequest', 'Poll', 'Report'
+    when 'Status', 'Follow', 'Favourite', 'StatusReaction', 'FollowRequest', 'Poll', 'Report'
       self.from_account_id = activity&.account_id
     when 'Mention'
       self.from_account_id = activity&.status&.account_id

app/models/status.rb

@@ -73,6 +73,7 @@ class Status < ApplicationRecord
   has_many :mentioned_accounts, through: :mentions, source: :account, class_name: 'Account'
   has_many :active_mentions, -> { active }, class_name: 'Mention', inverse_of: :status
   has_many :media_attachments, dependent: :nullify
+  has_many :status_reactions, inverse_of: :status, dependent: :destroy
 
   # Those associations are used for the private search index
   has_many :local_mentioned, -> { merge(Account.local) }, through: :active_mentions, source: :account
@@ -275,6 +276,21 @@ class Status < ApplicationRecord
     @emojis = CustomEmoji.from_text(fields.join(' '), account.domain)
   end
 
+  def reactions(account = nil)
+    records = begin
+      scope = status_reactions.group(:status_id, :name, :custom_emoji_id).order(Arel.sql('MIN(created_at) ASC'))
+
+      if account.nil?
+        scope.select('name, custom_emoji_id, count(*) as count, false as me')
+      else
+        scope.select("name, custom_emoji_id, count(*) as count, exists(select 1 from status_reactions r where r.account_id = #{account.id} and r.status_id = status_reactions.status_id and r.name = status_reactions.name and (r.custom_emoji_id = status_reactions.custom_emoji_id or r.custom_emoji_id is null and status_reactions.custom_emoji_id is null)) as me")
+      end
+    end
+
+    ActiveRecord::Associations::Preloader.new(records: records, associations: :custom_emoji)
+    records
+  end
+
   def ordered_media_attachments
     if ordered_media_attachment_ids.nil?
       media_attachments

app/models/status_reaction.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: status_reactions
+#
+#  id              :bigint(8)        not null, primary key
+#  account_id      :bigint(8)        not null
+#  status_id       :bigint(8)        not null
+#  name            :string           default(""), not null
+#  custom_emoji_id :bigint(8)
+#  created_at      :datetime         not null
+#  updated_at      :datetime         not null
+#
+class StatusReaction < ApplicationRecord
+  belongs_to :account
+  belongs_to :status, inverse_of: :status_reactions
+  belongs_to :custom_emoji, optional: true
+
+  has_one :notification, as: :activity, dependent: :destroy
+
+  validates :name, presence: true
+  validates_with StatusReactionValidator
+
+  before_validation :set_custom_emoji
+
+  private
+
+  # Sets custom_emoji to nil when disabled
+  def set_custom_emoji
+    self.custom_emoji = CustomEmoji.find_by(disabled: false, shortcode: name, domain: custom_emoji.domain) if name.present? && custom_emoji.present?
+  end
+end

app/models/user_settings.rb

@@ -18,6 +18,7 @@ class UserSettings
   setting :default_privacy, default: nil, in: %w(public unlisted private)
   setting :default_content_type, default: 'text/plain'
   setting :hide_followers_count, default: false
+  setting :visible_reactions, default: 6
 
   setting_inverse_alias :indexable, :noindex
   setting_inverse_alias :show_followers_count, :hide_followers_count

app/policies/status_policy.rb

@@ -28,6 +28,10 @@ class StatusPolicy < ApplicationPolicy
     show? && !blocking_author?
   end
 
+  def react?
+    show? && !blocking_author?
+  end
+
   def destroy?
     owned?
   end

app/serializers/activitypub/emoji_reaction_serializer.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+class ActivityPub::EmojiReactionSerializer < ActivityPub::Serializer
+  attributes :id, :type, :actor, :content
+  attribute :virtual_object, key: :object
+  attribute :custom_emoji, key: :tag, unless: -> { object.custom_emoji.nil? }
+
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.account), '#emoji_reactions/', object.id].join
+  end
+
+  def type
+    'EmojiReact'
+  end
+
+  def actor
+    ActivityPub::TagManager.instance.uri_for(object.account)
+  end
+
+  def virtual_object
+    ActivityPub::TagManager.instance.uri_for(object.status)
+  end
+
+  def content
+    if object.custom_emoji.nil?
+      object.name
+    else
+      ":#{object.name}:"
+    end
+  end
+
+  alias reaction content
+
+  # Akkoma (and possibly others) expect `tag` to be an array, so we can't just
+  # use the has_one shorthand because we need to wrap it into an array manually
+  def custom_emoji
+    [ActivityPub::EmojiSerializer.new(object.custom_emoji).serializable_hash]
+  end
+end

app/serializers/activitypub/undo_emoji_reaction_serializer.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class ActivityPub::UndoEmojiReactionSerializer < ActivityPub::Serializer
+  attributes :id, :type, :actor
+
+  has_one :object, serializer: ActivityPub::EmojiReactionSerializer
+
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.account), '#emoji_reactions/', object.id, '/undo'].join
+  end
+
+  def type
+    'Undo'
+  end
+
+  def actor
+    ActivityPub::TagManager.instance.uri_for(object.account)
+  end
+end

app/serializers/initial_state_serializer.rb

@@ -6,7 +6,7 @@ class InitialStateSerializer < ActiveModel::Serializer
   attributes :meta, :compose, :accounts,
              :media_attachments, :settings,
              :max_toot_chars, :poll_limits,
-             :languages
+             :languages, :max_reactions
 
   attribute :critical_updates_pending, if: -> { object&.role&.can?(:view_devops) && SoftwareUpdate.check_enabled? }
 
@@ -17,6 +17,10 @@ class InitialStateSerializer < ActiveModel::Serializer
     StatusLengthValidator::MAX_CHARS
   end
 
+  def max_reactions
+    StatusReactionValidator::LIMIT
+  end
+
   def poll_limits
     {
       max_options: PollValidator::MAX_OPTIONS,
@@ -68,6 +72,7 @@ class InitialStateSerializer < ActiveModel::Serializer
       store[:default_content_type] = object.current_account.user.setting_default_content_type
       store[:system_emoji_font] = object.current_account.user.setting_system_emoji_font
       store[:show_trends]       = Setting.trends && object.current_account.user.setting_trends
+      store[:visible_reactions] = object.current_account.user.setting_visible_reactions
     else
       store[:auto_play_gif] = Setting.auto_play_gif
       store[:display_media] = Setting.display_media

app/serializers/rest/instance_serializer.rb

@@ -78,6 +78,10 @@ class REST::InstanceSerializer < ActiveModel::Serializer
       translation: {
         enabled: TranslationService.configured?,
       },
+
+      reactions: {
+        max_reactions: StatusReactionValidator::LIMIT,
+      },
     }
   end
 

app/serializers/rest/notification_serializer.rb

@@ -12,7 +12,7 @@ class REST::NotificationSerializer < ActiveModel::Serializer
   end
 
   def status_type?
-    [:favourite, :reblog, :status, :mention, :poll, :update].include?(object.type)
+    [:favourite, :reaction, :reblog, :status, :mention, :poll, :update].include?(object.type)
   end
 
   def report_type?

app/serializers/rest/reaction_serializer.rb

@@ -21,6 +21,14 @@ class REST::ReactionSerializer < ActiveModel::Serializer
     object.custom_emoji.present?
   end
 
+  def name
+    if extern?
+      [object.name, '@', object.custom_emoji.domain].join
+    else
+      object.name
+    end
+  end
+
   def url
     full_asset_url(object.custom_emoji.image.url)
   end
@@ -28,4 +36,10 @@ class REST::ReactionSerializer < ActiveModel::Serializer
   def static_url
     full_asset_url(object.custom_emoji.image.url(:static))
   end
+
+  private
+
+  def extern?
+    custom_emoji? && object.custom_emoji.domain.present?
+  end
 end

app/serializers/rest/status_serializer.rb

@@ -28,6 +28,7 @@ class REST::StatusSerializer < ActiveModel::Serializer
   has_many :ordered_mentions, key: :mentions
   has_many :tags
   has_many :emojis, serializer: REST::CustomEmojiSerializer
+  has_many :reactions, serializer: REST::ReactionSerializer
 
   has_one :preview_card, key: :card, serializer: REST::PreviewCardSerializer
   has_one :preloadable_poll, key: :poll, serializer: REST::PollSerializer
@@ -156,6 +157,10 @@ class REST::StatusSerializer < ActiveModel::Serializer
     object.active_mentions.to_a.sort_by(&:id)
   end
 
+  def reactions
+    object.reactions(current_user&.account)
+  end
+
   private
 
   def relationships

app/serializers/rest/v1/instance_serializer.rb

@@ -97,6 +97,10 @@ class REST::V1::InstanceSerializer < ActiveModel::Serializer
         min_expiration: PollValidator::MIN_EXPIRATION,
         max_expiration: PollValidator::MAX_EXPIRATION,
       },
+
+      reactions: {
+        max_reactions: StatusReactionValidator::LIMIT,
+      },
     }
   end
 

app/services/react_service.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+class ReactService < BaseService
+  include Authorization
+  include Payloadable
+
+  def call(account, status, emoji)
+    authorize_with account, status, :react?
+
+    name, domain = emoji.split('@')
+    return unless domain.nil? || status.local?
+
+    custom_emoji = CustomEmoji.find_by(shortcode: name, domain: domain)
+    reaction = StatusReaction.find_by(account: account, status: status, name: name, custom_emoji: custom_emoji)
+    return reaction unless reaction.nil?
+
+    reaction = StatusReaction.create!(account: account, status: status, name: name, custom_emoji: custom_emoji)
+
+    json = Oj.dump(serialize_payload(reaction, ActivityPub::EmojiReactionSerializer))
+    if status.account.local?
+      NotifyService.new.call(status.account, :reaction, reaction)
+      ActivityPub::RawDistributionWorker.perform_async(json, status.account.id)
+    else
+      ActivityPub::DeliveryWorker.perform_async(json, reaction.account_id, status.account.inbox_url)
+    end
+
+    ActivityTracker.increment('activity:interactions')
+
+    reaction
+  end
+end

app/services/unreact_service.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+class UnreactService < BaseService
+  include Payloadable
+
+  def call(account, status, emoji)
+    name, domain = emoji.split('@')
+    custom_emoji = CustomEmoji.find_by(shortcode: name, domain: domain)
+    reaction = StatusReaction.find_by(account: account, status: status, name: name, custom_emoji: custom_emoji)
+    return if reaction.nil?
+
+    reaction.destroy!
+
+    json = Oj.dump(serialize_payload(reaction, ActivityPub::UndoEmojiReactionSerializer))
+    if status.account.local?
+      ActivityPub::RawDistributionWorker.perform_async(json, status.account.id)
+    else
+      ActivityPub::DeliveryWorker.perform_async(json, reaction.account_id, status.account.inbox_url)
+    end
+
+    reaction
+  end
+end

app/validators/status_reaction_validator.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+class StatusReactionValidator < ActiveModel::Validator
+  SUPPORTED_EMOJIS = Oj.load_file(Rails.root.join('app', 'javascript', 'mastodon', 'features', 'emoji', 'emoji_map.json').to_s).keys.freeze
+
+  LIMIT = [1, (ENV['MAX_REACTIONS'] || 1).to_i].max
+
+  def validate(reaction)
+    return if reaction.name.blank?
+
+    reaction.errors.add(:name, I18n.t('reactions.errors.unrecognized_emoji')) if reaction.custom_emoji_id.blank? && !unicode_emoji?(reaction.name)
+    reaction.errors.add(:base, I18n.t('reactions.errors.limit_reached')) if reaction.account.local? && new_reaction?(reaction) && limit_reached?(reaction)
+  end
+
+  private
+
+  def unicode_emoji?(name)
+    SUPPORTED_EMOJIS.include?(name)
+  end
+
+  def new_reaction?(reaction)
+    !reaction.status.status_reactions.exists?(status: reaction.status, account: reaction.account, name: reaction.name, custom_emoji: reaction.custom_emoji)
+  end
+
+  def limit_reached?(reaction)
+    reaction.status.status_reactions.where(status: reaction.status, account: reaction.account).count >= LIMIT
+  end
+end

app/views/settings/preferences/appearance/show.html.haml

@@ -36,6 +36,9 @@
       = ff.input :'web.use_system_font', wrapper: :with_label, label: I18n.t('simple_form.labels.defaults.setting_system_font_ui')
       = ff.input :'web.use_system_emoji_font', wrapper: :with_label, label: I18n.t('simple_form.labels.defaults.setting_system_emoji_font'), glitch_only: true
 
+    .fields-group.fields-row__column.fields-row__column-6
+      = ff.input :'visible_reactions', wrapper: :with_label, label: I18n.t('simple_form.labels.defaults.setting_visible_reactions'), input_html: { type: 'number', min: '0', data: { default: '6' } }, hint: false
+
     %h4= t 'appearance.discovery'
 
     .fields-group

app/workers/unreact_worker.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class UnreactWorker
+  include Sidekiq::Worker
+
+  def perform(account_id, status_id, emoji)
+    UnreactService.new.call(Account.find(account_id), Status.find(status_id), emoji)
+  rescue ActiveRecord::RecordNotFound
+    true
+  end
+end

config/locales-glitch/en.yml

@@ -38,5 +38,10 @@ en:
       title: User verification
   generic:
     use_this: Use this
+  notification_mailer:
+    reaction:
+      body: "%{name} reacted to your post:"
+      subject: "%{name} reacted to your post"
+      title: New reaction
   settings:
     flavours: Flavours

config/locales-glitch/simple_form.en.yml

@@ -20,6 +20,7 @@ en:
         setting_show_followers_count: Show your followers count
         setting_skin: Skin
         setting_system_emoji_font: Use system's default font for emojis (applies to Glitch flavour only)
+        setting_visible_reactions: Number of visible emoji reactions
       notification_emails:
         trending_link: New trending link requires review
         trending_status: New trending post requires review

config/routes/api.rb

@@ -16,6 +16,11 @@ namespace :api, format: false do
         resource :favourite, only: :create
         post :unfavourite, to: 'favourites#destroy'
 
+        # foreign custom emojis are encoded as shortcode@domain.tld
+        # the constraint prevents rails from interpreting the ".tld" as a filename extension
+        post '/react/:id', to: 'reactions#create', constraints: { id: %r{[^/]+} }
+        post '/unreact/:id', to: 'reactions#destroy', constraints: { id: %r{[^/]+} }
+
         resource :bookmark, only: :create
         post :unbookmark, to: 'bookmarks#destroy'
 

config/settings.yml

@@ -22,6 +22,7 @@ defaults: &defaults
   trends_as_landing_page: true
   trendable_by_default: false
   trending_status_cw: true
+  visible_reactions: 6
   hide_followers_count: false
   reserved_usernames:
     - admin

db/migrate/20221124114030_create_status_reactions.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class CreateStatusReactions < ActiveRecord::Migration[6.1]
+  def change
+    create_table :status_reactions do |t|
+      t.references :account, null: false, foreign_key: { on_delete: :cascade }
+      t.references :status, null: false, foreign_key: { on_delete: :cascade }
+      t.string :name, null: false, default: ''
+      t.references :custom_emoji, null: true, foreign_key: { on_delete: :cascade }
+
+      t.timestamps
+    end
+
+    add_index :status_reactions, [:account_id, :status_id, :name], unique: true, name: :index_status_reactions_on_account_id_and_status_id
+  end
+end

db/migrate/20221218015350_fix_foreign_keys_status_reactions.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+class FixForeignKeysStatusReactions < ActiveRecord::Migration[6.1]
+  disable_ddl_transaction!
+
+  def change
+    # Fixes an oversight in a previous version of the CreateStatusReactions migration
+    remove_foreign_key :status_reactions, :accounts
+    add_foreign_key :status_reactions, :accounts, on_delete: :cascade, validate: false
+    validate_foreign_key :status_reactions, :accounts
+    remove_foreign_key :status_reactions, :statuses
+    add_foreign_key :status_reactions, :statuses, on_delete: :cascade, validate: false
+    validate_foreign_key :status_reactions, :statuses
+    remove_foreign_key :status_reactions, :custom_emojis
+    add_foreign_key :status_reactions, :custom_emojis, on_delete: :cascade, validate: false
+    validate_foreign_key :status_reactions, :custom_emojis
+  end
+end

db/migrate/20230215074425_move_emoji_reaction_settings.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+class MoveEmojiReactionSettings < ActiveRecord::Migration[6.1]
+  class User < ApplicationRecord; end
+
+  MAPPING = {
+    setting_visible_reactions: 'visible_reactions',
+  }.freeze
+
+  class LegacySetting < ApplicationRecord
+    self.table_name = 'settings'
+
+    def var
+      self[:var]&.to_sym
+    end
+
+    def value
+      YAML.safe_load(self[:value], permitted_classes: [ActiveSupport::HashWithIndifferentAccess]) if self[:value].present?
+    end
+  end
+
+  def up
+    User.find_in_batches do |users|
+      previous_settings_for_batch = LegacySetting.where(thing_type: 'User', thing_id: users.map(&:id)).group_by(&:thing_id)
+
+      users.each do |user|
+        previous_settings = previous_settings_for_batch[user.id]&.index_by(&:var) || {}
+        user_settings = Oj.load(user.settings || '{}')
+        user_settings.delete('theme')
+
+        MAPPING.each do |legacy_key, new_key|
+          value = previous_settings[legacy_key]&.value
+
+          next if value.blank?
+
+          if value.is_a?(Hash)
+            value.each do |nested_key, nested_value|
+              user_settings[MAPPING[legacy_key][nested_key.to_sym]] = nested_value
+            end
+          else
+            user_settings[new_key] = value
+          end
+        end
+
+        user.update_column('settings', Oj.dump(user_settings)) # rubocop:disable Rails/SkipsModelValidations
+      end
+    end
+  end
+end

db/schema.rb

@@ -939,6 +939,18 @@ ActiveRecord::Schema[7.0].define(version: 2023_09_07_150100) do
     t.index ["status_id"], name: "index_status_pins_on_status_id"
   end
 
+  create_table "status_reactions", force: :cascade do |t|
+    t.bigint "account_id", null: false
+    t.bigint "status_id", null: false
+    t.string "name", default: "", null: false
+    t.bigint "custom_emoji_id"
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["account_id", "status_id", "name"], name: "index_status_reactions_on_account_id_and_status_id", unique: true
+    t.index ["custom_emoji_id"], name: "index_status_reactions_on_custom_emoji_id"
+    t.index ["status_id"], name: "index_status_reactions_on_status_id"
+  end
+
   create_table "status_stats", force: :cascade do |t|
     t.bigint "status_id", null: false
     t.bigint "replies_count", default: 0, null: false
@@ -1259,6 +1271,9 @@ ActiveRecord::Schema[7.0].define(version: 2023_09_07_150100) do
   add_foreign_key "status_edits", "statuses", on_delete: :cascade
   add_foreign_key "status_pins", "accounts", name: "fk_d4cb435b62", on_delete: :cascade
   add_foreign_key "status_pins", "statuses", on_delete: :cascade
+  add_foreign_key "status_reactions", "accounts", on_delete: :cascade
+  add_foreign_key "status_reactions", "custom_emojis", on_delete: :cascade
+  add_foreign_key "status_reactions", "statuses", on_delete: :cascade
   add_foreign_key "status_stats", "statuses", on_delete: :cascade
   add_foreign_key "status_trends", "accounts", on_delete: :cascade
   add_foreign_key "status_trends", "statuses", on_delete: :cascade

spec/fabricators/status_reaction_fabricator.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+Fabricator(:status_reaction) do
+  account
+  status
+  name '👍'
+  custom_emoji
+end

spec/models/status_reaction_spec.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+require 'rails_helper'