Show description changes in Maniphest

Summary:
When a task description is updated, there's currently no way to see the change.
Build an "expanded summary" mode for transactions that shows description change
details. Also include changes in the email.

Test Plan:
Changed task descriptions, clicked "show details", read email.

Reviewed By: aran
Reviewers: tuomaspelkonen, jungejason, aran
CC: anjali, aran, epriestley
Differential Revision: 320

src/applications/maniphest/controller/descriptionchange/ManiphestTaskDescriptionChangeController.php

@@ -0,0 +1,60 @@
+<?php
+
+/*
+ * Copyright 2011 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.
+ */
+
+class ManiphestTaskDescriptionChangeController extends ManiphestController {
+
+  private $transactionID;
+
+  public function willProcessRequest(array $data) {
+    $this->transactionID = $data['id'];
+  }
+
+  public function processRequest() {
+
+    $request = $this->getRequest();
+    $user = $request->getUser();
+
+    $transaction = id(new ManiphestTransaction())->load($this->transactionID);
+    if (!$transaction) {
+      return new Aphront404Response();
+    }
+
+    $transactions = array($transaction);
+
+    $phids = array();
+    foreach ($transactions as $transaction) {
+      foreach ($transaction->extractPHIDs() as $phid) {
+        $phids[$phid] = $phid;
+      }
+    }
+    $handles = id(new PhabricatorObjectHandleData($phids))->loadHandles();
+
+    $factory = new DifferentialMarkupEngineFactory();
+    $engine = $factory->newDifferentialCommentMarkupEngine();
+
+    $view = new ManiphestTransactionDetailView();
+    $view->setTransactionGroup($transactions);
+    $view->setHandles($handles);
+    $view->setMarkupEngine($engine);
+    $view->setRenderSummaryOnly(true);
+    $view->setRenderFullSummary(true);
+
+    return id(new AphrontAjaxResponse())->setContent($view->render());
+  }
+
+}

src/applications/maniphest/controller/descriptionchange/__init__.php

@@ -0,0 +1,20 @@
+<?php
+/**
+ * This file is automatically generated. Lint this module to rebuild it.
+ * @generated
+ */
+
+
+
+phutil_require_module('phabricator', 'aphront/response/404');
+phutil_require_module('phabricator', 'aphront/response/ajax');
+phutil_require_module('phabricator', 'applications/differential/parser/markup');
+phutil_require_module('phabricator', 'applications/maniphest/controller/base');
+phutil_require_module('phabricator', 'applications/maniphest/storage/transaction');
+phutil_require_module('phabricator', 'applications/maniphest/view/transactiondetail');
+phutil_require_module('phabricator', 'applications/phid/handle/data');
+
+phutil_require_module('phutil', 'utils');
+
+
+phutil_require_source('ManiphestTaskDescriptionChangeController.php');