Phriction - start the move towards transactions and an editor

Summary:
This implements as little as possible to stick a working transactions + editor codepath in the basic create / edit flow. Aside from the transaction tables, this also required adding a mailKey to a phrictionDocument.

Future work would include adding more transactions types for things like "move" and all the pertinent support. Even future work is to add things like policies which will work easily in the transaction framework. Ref T4029.

Test Plan:
 - made a wiki doc
 - edit a wiki doc
 - had someone subscribe to a wiki doc and edited it

For all three, the edits worked, a reasonable email was sent out, and feed stories were generated.

 - made a wiki doc at a /location/like/this

document "stubs" were made as expected in /location and /location/like

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: chad, Korvin, epriestley

Maniphest Tasks: T4029

Differential Revision: https://secure.phabricator.com/D10756

resources/sql/autopatches/20141025.phriction.1.xaction.sql

@@ -0,0 +1,19 @@
+CREATE TABLE {$NAMESPACE}_phriction.phriction_transaction (
+  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  phid VARCHAR(64) COLLATE utf8_bin NOT NULL,
+  authorPHID VARCHAR(64) COLLATE utf8_bin NOT NULL,
+  objectPHID VARCHAR(64) COLLATE utf8_bin NOT NULL,
+  viewPolicy VARCHAR(64) COLLATE utf8_bin NOT NULL,
+  editPolicy VARCHAR(64) COLLATE utf8_bin NOT NULL,
+  commentPHID VARCHAR(64) COLLATE utf8_bin DEFAULT NULL,
+  commentVersion INT UNSIGNED NOT NULL,
+  transactionType VARCHAR(32) COLLATE utf8_bin NOT NULL,
+  oldValue LONGTEXT COLLATE utf8_bin NOT NULL,
+  newValue LONGTEXT COLLATE utf8_bin NOT NULL,
+  contentSource LONGTEXT COLLATE utf8_bin NOT NULL,
+  metadata LONGTEXT COLLATE utf8_bin NOT NULL,
+  dateCreated INT UNSIGNED NOT NULL,
+  dateModified INT UNSIGNED NOT NULL,
+  UNIQUE KEY `key_phid` (`phid`),
+  KEY `key_object` (`objectPHID`)
+) ENGINE=InnoDB, COLLATE utf8_general_ci;

resources/sql/autopatches/20141025.phriction.2.xaction.sql

@@ -0,0 +1,16 @@
+CREATE TABLE {$NAMESPACE}_phriction.phriction_transaction_comment (
+  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  phid VARCHAR(64) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
+  transactionPHID VARCHAR(64) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,
+  authorPHID VARCHAR(64) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
+  viewPolicy VARCHAR(64) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
+  editPolicy VARCHAR(64) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
+  commentVersion INT UNSIGNED NOT NULL,
+  content LONGTEXT CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
+  contentSource LONGTEXT CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
+  isDeleted TINYINT(1) NOT NULL,
+  dateCreated INT UNSIGNED NOT NULL,
+  dateModified INT UNSIGNED NOT NULL,
+  UNIQUE KEY `key_phid` (`phid`),
+  UNIQUE KEY `key_version` (`transactionPHID`,`commentVersion`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8

resources/sql/autopatches/20141025.phriction.mailkey.sql

@@ -0,0 +1,2 @@
+ALTER TABLE {$NAMESPACE}_phriction.phriction_document
+  ADD mailKey VARCHAR(20) NOT NULL COLLATE utf8_bin;

src/__phutil_library_map__.php

@@ -2771,9 +2771,14 @@ phutil_register_library_map(array(
     'PhrictionMoveController' => 'applications/phriction/controller/PhrictionMoveController.php',
     'PhrictionNewController' => 'applications/phriction/controller/PhrictionNewController.php',
     'PhrictionRemarkupRule' => 'applications/phriction/markup/PhrictionRemarkupRule.php',
+    'PhrictionReplyHandler' => 'applications/phriction/mail/PhrictionReplyHandler.php',
     'PhrictionSchemaSpec' => 'applications/phriction/storage/PhrictionSchemaSpec.php',
     'PhrictionSearchEngine' => 'applications/phriction/query/PhrictionSearchEngine.php',
     'PhrictionSearchIndexer' => 'applications/phriction/search/PhrictionSearchIndexer.php',
+    'PhrictionTransaction' => 'applications/phriction/storage/PhrictionTransaction.php',
+    'PhrictionTransactionComment' => 'applications/phriction/storage/PhrictionTransactionComment.php',
+    'PhrictionTransactionEditor' => 'applications/phriction/editor/PhrictionTransactionEditor.php',
+    'PhrictionTransactionQuery' => 'applications/phriction/query/PhrictionTransactionQuery.php',
     'PonderAddAnswerView' => 'applications/ponder/view/PonderAddAnswerView.php',
     'PonderAnswer' => 'applications/ponder/storage/PonderAnswer.php',
     'PonderAnswerCommentController' => 'applications/ponder/controller/PonderAnswerCommentController.php',
@@ -5948,9 +5953,14 @@ phutil_register_library_map(array(
     'PhrictionMoveController' => 'PhrictionController',
     'PhrictionNewController' => 'PhrictionController',
     'PhrictionRemarkupRule' => 'PhutilRemarkupRule',
+    'PhrictionReplyHandler' => 'PhabricatorMailReplyHandler',
     'PhrictionSchemaSpec' => 'PhabricatorConfigSchemaSpec',
     'PhrictionSearchEngine' => 'PhabricatorApplicationSearchEngine',
     'PhrictionSearchIndexer' => 'PhabricatorSearchDocumentIndexer',
+    'PhrictionTransaction' => 'PhabricatorApplicationTransaction',
+    'PhrictionTransactionComment' => 'PhabricatorApplicationTransactionComment',
+    'PhrictionTransactionEditor' => 'PhabricatorApplicationTransactionEditor',
+    'PhrictionTransactionQuery' => 'PhabricatorApplicationTransactionQuery',
     'PonderAddAnswerView' => 'AphrontView',
     'PonderAnswer' => array(
       'PonderDAO',

src/applications/phriction/controller/PhrictionEditController.php

@@ -73,14 +73,8 @@ final class PhrictionEditController
             return new Aphront404Response();
           }
         }
-        $document = new PhrictionDocument();
-        $document->setSlug($slug);
-
-        $content  = new PhrictionContent();
-        $content->setSlug($slug);
-
-        $default_title = PhabricatorSlug::getDefaultTitle($slug);
-        $content->setTitle($default_title);
+        $document = PhrictionDocument::initializeNewDocument($user, $slug);
+        $content = $document->getContent();
       }
     }
 
@@ -174,13 +168,21 @@ final class PhrictionEditController
       }
 
       if (!count($errors)) {
-        $editor = id(PhrictionDocumentEditor::newForSlug($document->getSlug()))
-          ->setActor($user)
-          ->setTitle($title)
-          ->setContent($request->getStr('content'))
-          ->setDescription($notes);
 
-        $editor->save();
+        $xactions = array();
+        $xactions[] = id(new PhrictionTransaction())
+          ->setTransactionType(PhrictionTransaction::TYPE_TITLE)
+          ->setNewValue($title);
+        $xactions[] = id(new PhrictionTransaction())
+          ->setTransactionType(PhrictionTransaction::TYPE_CONTENT)
+          ->setNewValue($request->getStr('content'));
+
+        $editor = id(new PhrictionTransactionEditor())
+          ->setActor($user)
+          ->setContentSourceFromRequest($request)
+          ->setContinueOnNoEffect(true)
+          ->setDescription($notes)
+          ->applyTransactions($document, $xactions);
 
         if ($draft) {
           $draft->delete();

src/applications/phriction/editor/PhrictionDocumentEditor.php

@@ -106,7 +106,7 @@ final class PhrictionDocumentEditor extends PhabricatorEditor {
     return $this->execute(PhrictionChangeType::CHANGE_DELETE, true);
   }
 
-  private function stub() {
+  public function stub() {
     return $this->execute(PhrictionChangeType::CHANGE_STUB, true);
   }
 

src/applications/phriction/editor/PhrictionTransactionEditor.php

@@ -0,0 +1,298 @@
+<?php
+
+final class PhrictionTransactionEditor
+  extends PhabricatorApplicationTransactionEditor {
+
+  private $description;
+  private $oldContent;
+  private $newContent;
+
+  public function setDescription($description) {
+    $this->description = $description;
+    return $this;
+  }
+
+  private function getDescription() {
+    return $this->description;
+  }
+
+  private function setOldContent(PhrictionContent $content) {
+    $this->oldContent = $content;
+    return $this;
+  }
+
+  private function getOldContent() {
+    return $this->oldContent;
+  }
+
+  private function setNewContent(PhrictionContent $content) {
+    $this->newContent = $content;
+    return $this;
+  }
+
+  private function getNewContent() {
+    return $this->newContent;
+  }
+
+  public function getEditorApplicationClass() {
+    return 'PhabricatorPhrictionApplication';
+  }
+
+  public function getEditorObjectsDescription() {
+    return pht('Phriction Documents');
+  }
+
+  public function getTransactionTypes() {
+    $types = parent::getTransactionTypes();
+
+    $types[] = PhabricatorTransactions::TYPE_COMMENT;
+    $types[] = PhrictionTransaction::TYPE_TITLE;
+    $types[] = PhrictionTransaction::TYPE_CONTENT;
+
+    /* TODO
+    $types[] = PhabricatorTransactions::TYPE_VIEW_POLICY;
+    $types[] = PhabricatorTransactions::TYPE_EDIT_POLICY;
+     */
+
+    return $types;
+  }
+
+  protected function getCustomTransactionOldValue(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    switch ($xaction->getTransactionType()) {
+      case PhrictionTransaction::TYPE_TITLE:
+        if ($this->getIsNewObject()) {
+          return null;
+        }
+        return $this->getOldContent()->getTitle();
+      case PhrictionTransaction::TYPE_CONTENT:
+        if ($this->getIsNewObject()) {
+          return null;
+        }
+        return $this->getOldContent()->getContent();
+    }
+  }
+
+  protected function getCustomTransactionNewValue(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    switch ($xaction->getTransactionType()) {
+      case PhrictionTransaction::TYPE_TITLE:
+      case PhrictionTransaction::TYPE_CONTENT:
+        return $xaction->getNewValue();
+    }
+  }
+
+  protected function shouldApplyInitialEffects(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+
+    foreach ($xactions as $xaction) {
+      switch ($xaction->getTransactionType()) {
+      case PhrictionTransaction::TYPE_TITLE:
+      case PhrictionTransaction::TYPE_CONTENT:
+        return true;
+      }
+    }
+    return parent::shouldApplyInitialEffects($object, $xactions);
+  }
+
+  protected function applyInitialEffects(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+
+    $this->setOldContent($object->getContent());
+    $this->setNewContent($this->buildNewContentTemplate($object));
+  }
+
+  protected function applyCustomInternalTransaction(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    switch ($xaction->getTransactionType()) {
+      case PhrictionTransaction::TYPE_TITLE:
+      case PhrictionTransaction::TYPE_CONTENT:
+        $object->setStatus(PhrictionDocumentStatus::STATUS_EXISTS);
+        return;
+    }
+  }
+
+  protected function applyCustomExternalTransaction(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    switch ($xaction->getTransactionType()) {
+      case PhrictionTransaction::TYPE_TITLE:
+        $this->getNewContent()->setTitle($xaction->getNewValue());
+        break;
+      case PhrictionTransaction::TYPE_CONTENT:
+        $this->getNewContent()->setContent($xaction->getNewValue());
+        break;
+      default:
+        break;
+    }
+  }
+
+  protected function applyFinalEffects(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+
+    $save_content = false;
+    foreach ($xactions as $xaction) {
+      switch ($xaction->getTransactionType()) {
+        case PhrictionTransaction::TYPE_TITLE:
+        case PhrictionTransaction::TYPE_CONTENT:
+          $save_content = true;
+          break;
+        default:
+          break;
+      }
+    }
+
+    if ($save_content) {
+      $content = $this->getNewContent();
+      $content->setDocumentID($object->getID());
+      $content->save();
+
+      $object->setContentID($content->getID());
+      $object->save();
+      $object->attachContent($content);
+    }
+
+    if ($this->getIsNewObject()) {
+      // Stub out empty parent documents if they don't exist
+      $ancestral_slugs = PhabricatorSlug::getAncestry($object->getSlug());
+      if ($ancestral_slugs) {
+        $ancestors = id(new PhrictionDocument())->loadAllWhere(
+          'slug IN (%Ls)',
+          $ancestral_slugs);
+        $ancestors = mpull($ancestors, null, 'getSlug');
+        foreach ($ancestral_slugs as $slug) {
+          // We check for change type to prevent near-infinite recursion
+          if (!isset($ancestors[$slug]) &&
+            $content->getChangeType() !=
+            PhrictionChangeType::CHANGE_STUB) {
+              id(PhrictionDocumentEditor::newForSlug($slug))
+                ->setActor($this->getActor())
+                ->setTitle(PhabricatorSlug::getDefaultTitle($slug))
+                ->setContent('')
+                ->setDescription(pht('Empty Parent Document'))
+                ->stub();
+            }
+        }
+      }
+    }
+    return $xactions;
+  }
+
+  protected function shouldSendMail(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+
+    $xactions = mfilter($xactions, 'shouldHide', true);
+    return $xactions;
+  }
+
+  protected function getMailSubjectPrefix() {
+    return '[Phriction]';
+  }
+
+  protected function getMailTo(PhabricatorLiskDAO $object) {
+    return array(
+      $object->getContent()->getAuthorPHID(),
+      $this->getActingAsPHID(),
+    );
+  }
+
+  public function getMailTagsMap() {
+    return array(
+      PhrictionTransaction::MAILTAG_TITLE =>
+        pht("A document's title changes."),
+      PhrictionTransaction::MAILTAG_CONTENT =>
+        pht("A document's content changes."),
+    );
+  }
+
+  protected function buildReplyHandler(PhabricatorLiskDAO $object) {
+    return id(new PhrictionReplyHandler())
+      ->setMailReceiver($object);
+  }
+
+  protected function buildMailTemplate(PhabricatorLiskDAO $object) {
+    $id = $object->getID();
+    $title = $object->getContent()->getTitle();
+
+    return id(new PhabricatorMetaMTAMail())
+      ->setSubject($title)
+      ->addHeader('Thread-Topic', $object->getPHID());
+  }
+
+  protected function buildMailBody(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+
+    $body = parent::buildMailBody($object, $xactions);
+
+    if ($this->getIsNewObject()) {
+      $body->addTextSection(
+        pht('DOCUMENT CONTENT'),
+        $object->getContent()->getContent());
+    }
+
+    $body->addTextSection(
+      pht('DOCUMENT DETAIL'),
+      PhabricatorEnv::getProductionURI(
+        PhrictionDocument::getSlugURI($object->getSlug())));
+
+    return $body;
+  }
+
+  protected function shouldPublishFeedStory(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+    return $this->shouldSendMail($object, $xactions);
+  }
+
+  protected function getFeedRelatedPHIDs(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+
+    $phids = parent::getFeedRelatedPHIDs($object, $xactions);
+    // TODO - once the editor supports moves, we'll need to surface the
+    // "from document phid" to related phids.
+    return $phids;
+  }
+
+  protected function supportsSearch() {
+    return true;
+  }
+
+  protected function shouldApplyHeraldRules(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+    return false;
+  }
+
+  private function buildNewContentTemplate(
+    PhrictionDocument $document) {
+
+    $new_content = new PhrictionContent();
+    $new_content->setSlug($document->getSlug());
+    $new_content->setAuthorPHID($this->getActor()->getPHID());
+    $new_content->setChangeType(PhrictionChangeType::CHANGE_EDIT);
+
+    $new_content->setTitle($this->getOldContent()->getTitle());
+    $new_content->setContent($this->getOldContent()->getContent());
+
+    if (strlen($this->getDescription())) {
+      $new_content->setDescription($this->getDescription());
+    }
+    $new_content->setVersion($this->getOldContent()->getVersion() + 1);
+
+    return $new_content;
+  }
+
+}

src/applications/phriction/mail/PhrictionReplyHandler.php

@@ -0,0 +1,41 @@
+<?php
+
+final class PhrictionReplyHandler extends PhabricatorMailReplyHandler {
+
+  public function validateMailReceiver($mail_receiver) {
+    if (!($mail_receiver instanceof PhrictionDocument)) {
+      throw new Exception('Mail receiver is not a PhrictionDocument!');
+    }
+  }
+
+  public function getPrivateReplyHandlerEmailAddress(
+    PhabricatorObjectHandle $handle) {
+    return $this->getDefaultPrivateReplyHandlerEmailAddress(
+      $handle,
+      PhrictionDocumentPHIDType::TYPECONST);
+  }
+
+  public function getPublicReplyHandlerEmailAddress() {
+    return $this->getDefaultPublicReplyHandlerEmailAddress(
+      PhrictionDocumentPHIDType::TYPECONST);
+  }
+
+  public function getReplyHandlerDomain() {
+    return PhabricatorEnv::getEnvConfig('metamta.reply-handler-domain');
+  }
+
+  public function getReplyHandlerInstructions() {
+    if ($this->supportsReplies()) {
+      // TODO: Implement.
+      return null;
+    } else {
+      return null;
+    }
+  }
+
+  protected function receiveEmail(PhabricatorMetaMTAReceivedMail $mail) {
+    // TODO: Implement.
+    return null;
+  }
+
+}

src/applications/phriction/query/PhrictionTransactionQuery.php

@@ -0,0 +1,10 @@
+<?php
+
+final class PhrictionTransactionQuery
+  extends PhabricatorApplicationTransactionQuery {
+
+  public function getTemplateApplicationTransaction() {
+    return new PhrictionTransaction();
+  }
+
+}

src/applications/phriction/storage/PhrictionDocument.php

@@ -12,6 +12,7 @@ final class PhrictionDocument extends PhrictionDAO
   protected $depth;
   protected $contentID;
   protected $status;
+  protected $mailKey;
 
   private $contentObject = self::ATTACHABLE;
   private $ancestors = array();
@@ -53,6 +54,27 @@ final class PhrictionDocument extends PhrictionDAO
       PhrictionDocumentPHIDType::TYPECONST);
   }
 
+  public static function initializeNewDocument(PhabricatorUser $actor, $slug) {
+    $document = new PhrictionDocument();
+    $document->setSlug($slug);
+
+    $content  = new PhrictionContent();
+    $content->setSlug($slug);
+
+    $default_title = PhabricatorSlug::getDefaultTitle($slug);
+    $content->setTitle($default_title);
+    $document->attachContent($content);
+
+    return $document;
+  }
+
+  public function save() {
+    if (!$this->getMailKey()) {
+      $this->setMailKey(Filesystem::readRandomCharacters(20));
+    }
+    return parent::save();
+  }
+
   public static function getSlugURI($slug, $type = 'document') {
     static $types = array(
       'document'  => '/w/',

src/applications/phriction/storage/PhrictionTransaction.php

@@ -0,0 +1,186 @@
+<?php
+
+final class PhrictionTransaction
+  extends PhabricatorApplicationTransaction {
+
+  const TYPE_TITLE = 'title';
+  const TYPE_CONTENT = 'content';
+
+  const MAILTAG_TITLE = 'phriction-title';
+  const MAILTAG_CONTENT = 'phriction-content';
+
+  public function getApplicationName() {
+    return 'phriction';
+  }
+
+  public function getApplicationTransactionType() {
+    return PhrictionDocumentPHIDType::TYPECONST;
+  }
+
+  public function getApplicationTransactionCommentObject() {
+    return new PhrictionTransactionComment();
+  }
+
+  public function getRemarkupBlocks() {
+    $blocks = parent::getRemarkupBlocks();
+
+    switch ($this->getTransactionType()) {
+      case self::TYPE_CONTENT:
+        $blocks[] = $this->getNewValue();
+        break;
+    }
+
+    return $blocks;
+  }
+
+  public function shouldHide() {
+    switch ($this->getTransactionType()) {
+      case self::TYPE_CONTENT:
+        if ($this->getOldValue() === null) {
+          return true;
+        } else {
+          return false;
+        }
+        break;
+    }
+
+    return parent::shouldHide();
+  }
+
+  public function getActionStrength() {
+    switch ($this->getTransactionType()) {
+      case self::TYPE_TITLE:
+        return 1.4;
+      case self::TYPE_CONTENT:
+        return 1.3;
+    }
+
+    return parent::getActionStrength();
+  }
+
+  public function getActionName() {
+    $old = $this->getOldValue();
+    $new = $this->getNewValue();
+
+    switch ($this->getTransactionType()) {
+      case self::TYPE_TITLE:
+        if ($old === null) {
+          return pht('Created');
+        }
+
+        return pht('Retitled');
+
+      case self::TYPE_CONTENT:
+        return pht('Edited');
+
+    }
+
+    return parent::getActionName();
+  }
+
+  public function getIcon() {
+    $old = $this->getOldValue();
+    $new = $this->getNewValue();
+
+    switch ($this->getTransactionType()) {
+      case self::TYPE_TITLE:
+      case self::TYPE_CONTENT:
+        return 'fa-pencil';
+    }
+
+    return parent::getIcon();
+  }
+
+
+
+  public function getTitle() {
+    $author_phid = $this->getAuthorPHID();
+
+    $old = $this->getOldValue();
+    $new = $this->getNewValue();
+
+    switch ($this->getTransactionType()) {
+      case self::TYPE_TITLE:
+        if ($old === null) {
+          return pht(
+            '%s created this document.',
+            $this->renderHandleLink($author_phid));
+        }
+        return pht(
+          '%s changed the title from "%s" to "%s".',
+          $this->renderHandleLink($author_phid),
+          $old,
+          $new);
+
+      case self::TYPE_CONTENT:
+        return pht(
+          '%s edited the document content.',
+          $this->renderHandleLink($author_phid));
+
+    }
+
+    return parent::getTitle();
+  }
+
+  public function getTitleForFeed(PhabricatorFeedStory $story) {
+    $author_phid = $this->getAuthorPHID();
+    $object_phid = $this->getObjectPHID();
+
+    $old = $this->getOldValue();
+    $new = $this->getNewValue();
+
+    switch ($this->getTransactionType()) {
+      case self::TYPE_TITLE:
+        if ($old === null) {
+          return pht(
+            '%s created %s.',
+            $this->renderHandleLink($author_phid),
+            $this->renderHandleLink($object_phid));
+        }
+
+        return pht(
+          '%s renamed %s from "%s" to "%s".',
+          $this->renderHandleLink($author_phid),
+          $this->renderHandleLink($object_phid),
+          $old,
+          $new);
+
+      case self::TYPE_CONTENT:
+        return pht(
+          '%s edited the content of %s.',
+          $this->renderHandleLink($author_phid),
+          $this->renderHandleLink($object_phid));
+
+    }
+    return parent::getTitleForFeed($story);
+  }
+
+  public function hasChangeDetails() {
+    switch ($this->getTransactionType()) {
+      case self::TYPE_CONTENT:
+        return true;
+    }
+    return parent::hasChangeDetails();
+  }
+
+  public function renderChangeDetails(PhabricatorUser $viewer) {
+    return $this->renderTextCorpusChangeDetails(
+      $viewer,
+      $this->getOldValue(),
+      $this->getNewValue());
+  }
+
+  public function getMailTags() {
+    $tags = array();
+    switch ($this->getTransactionType()) {
+      case self::TYPE_TITLE:
+        $tags[] = self::MAILTAG_TITLE;
+        break;
+      case self::TYPE_CONTENT:
+        $tags[] = self::MAILTAG_CONTENT;
+        break;
+    }
+    return $tags;
+  }
+
+}

src/applications/phriction/storage/PhrictionTransactionComment.php

@@ -0,0 +1,10 @@
+<?php
+
+final class PhrictionTransactionComment
+  extends PhabricatorApplicationTransactionComment {
+
+  public function getApplicationTransactionObject() {
+    return new PhrictionTransaction();
+  }
+
+}