Add basic "Subscriptions" application

Summary:
Basic infrastructure for generalizing subscriptions/CCs for T1808, T1514 and T1663.

  - Implement `PhabricatorSubscribableInterface` and you'll get a subscribe/unsubscribe button for free.
  - If there are any auto-subscribed users (like the question author) you can specify them; this makes more sense for Tasks and Revisions than Ponder probably, but maybe the author should be auto-subscribed.
  - Subscriptions are either "explicit" (the user clicked 'subscribe') or "implicit" (the user did something which causes them to become subscribed naturally). If a user unsubscribes, they'll no longer be added by implicit subscriptions. This may or may not be relevant to Ponder but is an existing Herald feature in Differential.
  - Helper method on PhabricatorSubscribersQuery to load subscribers.
  - This doesn't handle actually sending email, etc. I think that's all so application-specific that it doesn't belong here.
  - Now seems to work.

Test Plan:
{F20552}
{F20553}

Reviewers: pieter, btrahan

Reviewed By: pieter

CC: aran

Maniphest Tasks: T1663, T1514, T1808

Differential Revision: https://secure.phabricator.com/D3637

scripts/celerity/generate_sprites.php

@@ -169,18 +169,21 @@ $action_template = id(new PhutilSprite())
   ->setSourceSize(16, 16);
 
 $action_map = array(
-  'file'        => 'icon/page_white_text.png',
-  'fork'        => 'icon/arrow_branch.png',
-  'edit'        => 'icon/page_white_edit.png',
-  'flag-0'      => 'icon/flag-0.png',
-  'flag-1'      => 'icon/flag-1.png',
-  'flag-2'      => 'icon/flag-2.png',
-  'flag-3'      => 'icon/flag-3.png',
-  'flag-4'      => 'icon/flag-4.png',
-  'flag-5'      => 'icon/flag-5.png',
-  'flag-6'      => 'icon/flag-6.png',
-  'flag-7'      => 'icon/flag-7.png',
-  'flag-ghost'  => 'icon/flag-ghost.png',
+  'file'              => 'icon/page_white_text.png',
+  'fork'              => 'icon/arrow_branch.png',
+  'edit'              => 'icon/page_white_edit.png',
+  'flag-0'            => 'icon/flag-0.png',
+  'flag-1'            => 'icon/flag-1.png',
+  'flag-2'            => 'icon/flag-2.png',
+  'flag-3'            => 'icon/flag-3.png',
+  'flag-4'            => 'icon/flag-4.png',
+  'flag-5'            => 'icon/flag-5.png',
+  'flag-6'            => 'icon/flag-6.png',
+  'flag-7'            => 'icon/flag-7.png',
+  'flag-ghost'        => 'icon/flag-ghost.png',
+  'subscribe-auto'    => 'icon/unsubscribe.png',
+  'subscribe-add'     => 'icon/subscribe.png',
+  'subscribe-delete'  => 'icon/unsubscribe.png',
 );
 
 foreach ($action_map as $icon => $source) {

src/__phutil_library_map__.php

@@ -581,6 +581,7 @@ phutil_register_library_map(array(
     'PhabricatorApplicationSettings' => 'applications/settings/application/PhabricatorApplicationSettings.php',
     'PhabricatorApplicationSlowvote' => 'applications/slowvote/application/PhabricatorApplicationSlowvote.php',
     'PhabricatorApplicationStatusView' => 'applications/meta/view/PhabricatorApplicationStatusView.php',
+    'PhabricatorApplicationSubscriptions' => 'applications/subscriptions/application/PhabricatorApplicationSubscriptions.php',
     'PhabricatorApplicationUIExamples' => 'applications/uiexample/application/PhabricatorApplicationUIExamples.php',
     'PhabricatorApplicationsListController' => 'applications/meta/controller/PhabricatorApplicationsListController.php',
     'PhabricatorAuditActionConstants' => 'applications/audit/constants/PhabricatorAuditActionConstants.php',
@@ -1078,6 +1079,11 @@ phutil_register_library_map(array(
     'PhabricatorStorageManagementUpgradeWorkflow' => 'infrastructure/storage/management/workflow/PhabricatorStorageManagementUpgradeWorkflow.php',
     'PhabricatorStorageManagementWorkflow' => 'infrastructure/storage/management/workflow/PhabricatorStorageManagementWorkflow.php',
     'PhabricatorStoragePatch' => 'infrastructure/storage/management/PhabricatorStoragePatch.php',
+    'PhabricatorSubscribableInterface' => 'applications/subscriptions/interface/PhabricatorSubscribableInterface.php',
+    'PhabricatorSubscribersQuery' => 'applications/subscriptions/query/PhabricatorSubscribersQuery.php',
+    'PhabricatorSubscriptionsEditController' => 'applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php',
+    'PhabricatorSubscriptionsEditor' => 'applications/subscriptions/editor/PhabricatorSubscriptionsEditor.php',
+    'PhabricatorSubscriptionsUIEventListener' => 'applications/subscriptions/events/PhabricatorSubscriptionsUIEventListener.php',
     'PhabricatorSymbolNameLinter' => 'infrastructure/lint/hook/PhabricatorSymbolNameLinter.php',
     'PhabricatorSyntaxHighlighter' => 'infrastructure/markup/PhabricatorSyntaxHighlighter.php',
     'PhabricatorTaskmasterDaemon' => 'infrastructure/daemon/workers/PhabricatorTaskmasterDaemon.php',
@@ -1691,6 +1697,7 @@ phutil_register_library_map(array(
     'ManiphestTaskPriority' => 'ManiphestConstants',
     'ManiphestTaskProject' => 'ManiphestDAO',
     'ManiphestTaskProjectsView' => 'ManiphestView',
+    'ManiphestTaskQuery' => 'PhabricatorQuery',
     'ManiphestTaskStatus' => 'ManiphestConstants',
     'ManiphestTaskSubscriber' => 'ManiphestDAO',
     'ManiphestTaskSummaryView' => 'ManiphestView',
@@ -1746,6 +1753,7 @@ phutil_register_library_map(array(
     'PhabricatorApplicationSettings' => 'PhabricatorApplication',
     'PhabricatorApplicationSlowvote' => 'PhabricatorApplication',
     'PhabricatorApplicationStatusView' => 'AphrontView',
+    'PhabricatorApplicationSubscriptions' => 'PhabricatorApplication',
     'PhabricatorApplicationUIExamples' => 'PhabricatorApplication',
     'PhabricatorApplicationsListController' => 'PhabricatorController',
     'PhabricatorAuditAddCommentController' => 'PhabricatorAuditController',
@@ -2185,6 +2193,9 @@ phutil_register_library_map(array(
     'PhabricatorStorageManagementStatusWorkflow' => 'PhabricatorStorageManagementWorkflow',
     'PhabricatorStorageManagementUpgradeWorkflow' => 'PhabricatorStorageManagementWorkflow',
     'PhabricatorStorageManagementWorkflow' => 'PhutilArgumentWorkflow',
+    'PhabricatorSubscribersQuery' => 'PhabricatorQuery',
+    'PhabricatorSubscriptionsEditController' => 'PhabricatorController',
+    'PhabricatorSubscriptionsUIEventListener' => 'PhutilEventListener',
     'PhabricatorSymbolNameLinter' => 'ArcanistXHPASTLintNamingHook',
     'PhabricatorTaskmasterDaemon' => 'PhabricatorDaemon',
     'PhabricatorTestCase' => 'ArcanistPhutilTestCase',

src/applications/phid/handle/PhabricatorObjectHandleData.php

@@ -102,6 +102,14 @@ final class PhabricatorObjectHandleData {
             $objects[$revision->getPHID()] = $revision;
           }
           break;
+        case PhabricatorPHIDConstants::PHID_TYPE_QUES:
+          $questions = id(new PonderQuestionQuery())
+            ->withPHIDs($phids)
+            ->execute();
+          foreach ($questions as $question) {
+            $objects[$question->getPHID()] = $question;
+          }
+          break;
       }
     }
 

src/applications/subscriptions/application/PhabricatorApplicationSubscriptions.php

@@ -0,0 +1,41 @@
+<?php
+
+/*
+ * Copyright 2012 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+final class PhabricatorApplicationSubscriptions extends PhabricatorApplication {
+
+  public function shouldAppearInLaunchView() {
+    return false;
+  }
+
+  public function getEventListeners() {
+    return array(
+      new PhabricatorSubscriptionsUIEventListener(),
+    );
+  }
+
+  public function getRoutes() {
+    return array(
+      '/subscriptions/' => array(
+        '(?P<action>add|delete)/'.
+        '(?P<phid>[^/]+)/' => 'PhabricatorSubscriptionsEditController',
+      ),
+    );
+  }
+
+}
+

src/applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php

@@ -0,0 +1,106 @@
+<?php
+
+/*
+ * Copyright 2012 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+final class PhabricatorSubscriptionsEditController
+  extends PhabricatorController {
+
+  private $phid;
+  private $action;
+
+  public function willProcessRequest(array $data) {
+    $this->phid = idx($data, 'phid');
+    $this->action = idx($data, 'action');
+  }
+
+  public function processRequest() {
+    $request = $this->getRequest();
+
+    if (!$request->isFormPost()) {
+      return new Aphront400Response();
+    }
+
+    switch ($this->action) {
+      case 'add':
+        $is_add = true;
+        break;
+      case 'delete':
+        $is_add = false;
+        break;
+      default:
+        return new Aphront400Response();
+    }
+
+    $user = $request->getUser();
+    $phid = $this->phid;
+
+    // TODO: This is a policy test because `loadObjects()` is not currently
+    // policy-aware. Once it is, we can collapse this.
+    $handle = PhabricatorObjectHandleData::loadOneHandle($phid, $user);
+    if (!$handle->isComplete()) {
+      return new Aphront404Response();
+    }
+
+    $objects = id(new PhabricatorObjectHandleData(array($phid)))
+      ->loadObjects();
+    $object = idx($objects, $phid);
+
+    if (!($object instanceof PhabricatorSubscribableInterface)) {
+      return $this->buildErrorResponse(
+        pht('Bad Object'),
+        pht('This object is not subscribable.'),
+        $handle->getURI());
+    }
+
+    if ($object->isAutomaticallySubscribed($user->getPHID())) {
+      return $this->buildErrorResponse(
+        pht('Automatically Subscribed'),
+        pht('You are automatically subscribed to this object.'),
+        $handle->getURI());
+    }
+
+    $editor = id(new PhabricatorSubscriptionsEditor())
+      ->setUser($user)
+      ->setObject($object);
+
+    if ($is_add) {
+      $editor->subscribeExplicit(array($user->getPHID()), $explicit = true);
+    } else {
+      $editor->unsubscribe(array($user->getPHID()));
+    }
+
+    $editor->save();
+
+    // TODO: We should just render the "Unsubscribe" action and swap it out
+    // in the document for Ajax requests.
+    return id(new AphrontReloadResponse())->setURI($handle->getURI());
+  }
+
+  private function buildErrorResponse($title, $message, $uri) {
+    $request = $this->getRequest();
+    $user = $request->getUser();
+
+    $dialog = id(new AphrontDialogView())
+      ->setUser($user)
+      ->setTitle($title)
+      ->appendChild($message)
+      ->addCancelButton($uri);
+
+    return id(new AphrontDialogResponse())->setDialog($dialog);
+  }
+
+}

src/applications/subscriptions/editor/PhabricatorSubscriptionsEditor.php

@@ -0,0 +1,128 @@
+<?php
+
+/*
+ * Copyright 2012 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+final class PhabricatorSubscriptionsEditor {
+
+  private $object;
+  private $user;
+
+  private $explicitSubscribePHIDs = array();
+  private $implicitSubscribePHIDs = array();
+  private $unsubscribePHIDs       = array();
+
+  public function setObject(PhabricatorSubscribableInterface $object) {
+    $this->object = $object;
+    return $this;
+  }
+
+  public function setUser(PhabricatorUser $user) {
+    $this->user = $user;
+    return $this;
+  }
+
+
+  /**
+   * Add explicit subscribers. These subscribers have explicitly subscribed
+   * (or been subscribed) to the object, and will be added even if they
+   * had previously unsubscribed.
+   *
+   * @param list<phid>  List of PHIDs to explicitly subscribe.
+   * @return this
+   */
+  public function subscribeExplicit(array $phids) {
+    $this->explicitSubscribePHIDs += array_fill_keys($phids, true);
+    return $this;
+  }
+
+
+  /**
+   * Add implicit subscribers. These subscribers have taken some action which
+   * implicitly subscribes them (e.g., adding a comment) but it will be
+   * suppressed if they've previously unsubscribed from the object.
+   *
+   * @param list<phid>  List of PHIDs to implicitly subscribe.
+   * @return this
+   */
+  public function subscribeImplicit(array $phids) {
+    $this->implicitSubscribePHIDs += array_fill_keys($phids, true);
+    return $this;
+  }
+
+
+  /**
+   * Unsubscribe PHIDs and mark them as unsubscribed, so implicit subscriptions
+   * will not resubscribe them.
+   *
+   * @param list<phid>  List of PHIDs to unsubscribe.
+   * @return this
+   */
+  public function unsubscribe(array $phids) {
+    $this->unsubscribePHIDs += array_fill_keys($phids, true);
+    return $this;
+  }
+
+
+  public function save() {
+    if (!$this->object) {
+      throw new Exception('Call setObject() before save()!');
+    }
+    if (!$this->user) {
+      throw new Exception('Call setUser() before save()!');
+    }
+
+    $src = $this->object->getPHID();
+
+    if ($this->implicitSubscribePHIDs) {
+      $unsub = PhabricatorEdgeQuery::loadDestinationPHIDs(
+        $src,
+        PhabricatorEdgeConfig::TYPE_OBJECT_HAS_UNSUBSCRIBER);
+      $unsub = array_fill_keys($unsub, true);
+      $this->implicitSubscribePHIDs = array_diff_key(
+        $this->implicitSubscribePHIDs,
+        $unsub);
+    }
+
+    $add = $this->implicitSubscribePHIDs + $this->explicitSubscribePHIDs;
+    $del = $this->unsubscribePHIDs;
+
+    // If a PHID is marked for both subscription and unsubscription, treat
+    // unsubscription as the stronger action.
+    $add = array_diff_key($add, $del);
+
+    if ($add || $del) {
+      $u_type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_UNSUBSCRIBER;
+      $s_type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_SUBSCRIBER;
+
+      $editor = id(new PhabricatorEdgeEditor())
+        ->setUser($this->user);
+
+      foreach ($add as $phid => $ignored) {
+        $editor->removeEdge($src, $u_type, $phid);
+        $editor->addEdge($src, $s_type, $phid);
+      }
+
+      foreach ($del as $phid => $ignored) {
+        $editor->removeEdge($src, $s_type, $phid);
+        $editor->addEdge($src, $u_type, $phid);
+      }
+
+      $editor->save();
+    }
+  }
+
+}

src/applications/subscriptions/events/PhabricatorSubscriptionsUIEventListener.php

@@ -0,0 +1,100 @@
+<?php
+
+/*
+ * Copyright 2012 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+final class PhabricatorSubscriptionsUIEventListener
+  extends PhutilEventListener {
+
+  public function register() {
+    $this->listen(PhabricatorEventType::TYPE_UI_DIDRENDERACTIONS);
+  }
+
+  public function handleEvent(PhutilEvent $event) {
+    switch ($event->getType()) {
+      case PhabricatorEventType::TYPE_UI_DIDRENDERACTIONS:
+        $this->handleActionEvent($event);
+      break;
+    }
+  }
+
+  private function handleActionEvent($event) {
+    $user = $event->getUser();
+    $object = $event->getValue('object');
+
+    if (!$object || !$object->getPHID()) {
+      // No object, or the object has no PHID yet. No way to subscribe.
+      return;
+    }
+
+    if (!($object instanceof PhabricatorSubscribableInterface)) {
+      // This object isn't subscribable.
+      return;
+    }
+
+    if ($object->isAutomaticallySubscribed($user->getPHID())) {
+      $sub_action = id(new PhabricatorActionView())
+        ->setWorkflow(true)
+        ->setUser($user)
+        ->setDisabled(true)
+        ->setRenderAsForm(true)
+        ->setHref('/subscriptions/add/'.$object->getPHID().'/')
+        ->setName(phutil_escape_html('Automatically Subscribed'))
+        ->setIcon('subscribe-auto');
+    } else {
+      $subscribed = false;
+      if ($user->isLoggedIn()) {
+        $src_phid = $object->getPHID();
+        $dst_phid = $user->getPHID();
+        $edge_type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_SUBSCRIBER;
+
+        $edges = id(new PhabricatorEdgeQuery())
+          ->withSourcePHIDs(array($src_phid))
+          ->withEdgeTypes(array($edge_type))
+          ->withDestinationPHIDs(array($user->getPHID()))
+          ->execute();
+        $subscribed = isset($edges[$src_phid][$edge_type][$dst_phid]);
+      }
+
+      if ($subscribed) {
+        $sub_action = id(new PhabricatorActionView())
+          ->setUser($user)
+          ->setWorkflow(true)
+          ->setRenderAsForm(true)
+          ->setHref('/subscriptions/delete/'.$object->getPHID().'/')
+          ->setName(phutil_escape_html('Unsubscribe'))
+          ->setIcon('subscribe-delete');
+      } else {
+        $sub_action = id(new PhabricatorActionView())
+          ->setUser($user)
+          ->setWorkflow(true)
+          ->setRenderAsForm(true)
+          ->setHref('/subscriptions/add/'.$object->getPHID().'/')
+          ->setName(phutil_escape_html('Subscribe'))
+          ->setIcon('subscribe-add');
+      }
+
+      if (!$user->isLoggedIn()) {
+        $sub_action->setDisabled(true);
+      }
+    }
+
+    $actions = $event->getValue('actions');
+    $actions[] = $sub_action;
+    $event->setValue('actions', $actions);
+  }
+
+}

src/applications/subscriptions/interface/PhabricatorSubscribableInterface.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * Copyright 2012 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+interface PhabricatorSubscribableInterface {
+
+  /**
+   * Return true to indicate that the given PHID is automatically subscribed
+   * to the object (for example, they are the author or in some other way
+   * irrevocably a subscriber). This will, e.g., cause the UI to render
+   * "Automatically Subscribed" instead of "Subscribe".
+   *
+   * @param PHID  PHID (presumably a user) to test for automatic subscription.
+   * @return bool True if the object/user is automatically subscribed.
+   */
+  public function isAutomaticallySubscribed($phid);
+
+}

src/applications/subscriptions/query/PhabricatorSubscribersQuery.php

@@ -0,0 +1,66 @@
+<?php
+
+/*
+ * Copyright 2012 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+final class PhabricatorSubscribersQuery extends PhabricatorQuery {
+
+  private $objectPHIDs;
+  private $subscriberPHIDs;
+
+  public static function loadSubscribersForPHID($phid) {
+    $subscribers = id(new PhabricatorSubscribersQuery())
+      ->withObjectPHIDs(array($phid))
+      ->execute();
+    return $subscribers[$phid];
+  }
+
+  public function withObjectPHIDs(array $object_phids) {
+    $this->objectPHIDs = $object_phids;
+    return $this;
+  }
+
+  public function withSubscriberPHIDs(array $subscriber_phids) {
+    $this->subscriberPHIDs = $subscriber_phids;
+    return $this;
+  }
+
+  public function execute() {
+    $query = new PhabricatorEdgeQuery();
+
+    $edge_type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_SUBSCRIBER;
+
+    $query->withSourcePHIDs($this->objectPHIDs);
+    $query->withEdgeTypes(array($edge_type));
+
+    if ($this->subscriberPHIDs) {
+      $query->withDestinationPHIDs($this->subscriberPHIDs);
+    }
+
+    $edges = $query->execute();
+
+    $results = array_fill_keys($this->objectPHIDs, array());
+    foreach ($edges as $src => $edge_types) {
+      foreach ($edge_types[$edge_type] as $dst => $data) {
+        $results[$src][] = $dst;
+      }
+    }
+
+    return $results;
+  }
+
+
+}

src/infrastructure/edges/constants/PhabricatorEdgeConfig.php

@@ -49,6 +49,12 @@ final class PhabricatorEdgeConfig extends PhabricatorEdgeConstants {
   const TYPE_ANSWER_HAS_VOTING_USER     = 19;
   const TYPE_VOTING_USER_HAS_ANSWER     = 20;
 
+  const TYPE_OBJECT_HAS_SUBSCRIBER      = 21;
+  const TYPE_SUBSCRIBED_TO_OBJECT       = 22;
+
+  const TYPE_OBJECT_HAS_UNSUBSCRIBER    = 23;
+  const TYPE_UNSUBSCRIBED_FROM_OBJECT   = 24;
+
   const TYPE_TEST_NO_CYCLE              = 9000;
 
   public static function getInverse($edge_type) {
@@ -82,6 +88,12 @@ final class PhabricatorEdgeConfig extends PhabricatorEdgeConstants {
         self::TYPE_QUESTION_HAS_VOTING_USER,
       self::TYPE_ANSWER_HAS_VOTING_USER => self::TYPE_VOTING_USER_HAS_ANSWER,
       self::TYPE_VOTING_USER_HAS_ANSWER => self::TYPE_ANSWER_HAS_VOTING_USER,
+
+      self::TYPE_OBJECT_HAS_SUBSCRIBER => self::TYPE_SUBSCRIBED_TO_OBJECT,
+      self::TYPE_SUBSCRIBED_TO_OBJECT => self::TYPE_OBJECT_HAS_SUBSCRIBER,
+
+      self::TYPE_OBJECT_HAS_UNSUBSCRIBER => self::TYPE_UNSUBSCRIBED_FROM_OBJECT,
+      self::TYPE_UNSUBSCRIBED_FROM_OBJECT => self::TYPE_OBJECT_HAS_UNSUBSCRIBER,
     );
 
     return idx($map, $edge_type);

webroot/rsrc/css/autosprite.css

@@ -363,3 +363,15 @@
 .action-flag-ghost {
   background-position: 0px -3444px;
 }
+
+.action-subscribe-auto {
+  background-position: 0px -3461px;
+}
+
+.action-subscribe-add {
+  background-position: 0px -3478px;
+}
+
+.action-subscribe-delete {
+  background-position: 0px -3495px;
+}