Allow transactions to specialize their mail headers for diff sections

Summary: Ref T7643. When we send mail about a change to a package description, allow it to say "CHANGES TO PACKAGE DESCRIPTION" instead of "EDIT DETAILS". Smooth!

Test Plan: {F1909417}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T7643

Differential Revision: https://secure.phabricator.com/D16818

src/applications/calendar/xaction/PhabricatorCalendarEventDescriptionTransaction.php

@@ -30,6 +30,10 @@ final class PhabricatorCalendarEventDescriptionTransaction
     return true;
   }
 
+  public function getMailDiffSectionHeader() {
+    return pht('CHANGES TO EVENT DESCRIPTION');
+  }
+
   public function newChangeDetailView() {
     $viewer = $this->getViewer();
 

src/applications/owners/xaction/PhabricatorOwnersPackageDescriptionTransaction.php

@@ -19,6 +19,10 @@ final class PhabricatorOwnersPackageDescriptionTransaction
       $this->renderAuthor());
   }
 
+  public function getMailDiffSectionHeader() {
+    return pht('CHANGES TO PACKAGE DESCRIPTION');
+  }
+
   public function newChangeDetailView() {
     return id(new PhabricatorApplicationTransactionTextDiffDetailView())
       ->setViewer($this->getViewer())

src/applications/paste/xaction/PhabricatorPasteContentTransaction.php

@@ -104,6 +104,10 @@ final class PhabricatorPasteContentTransaction
     return true;
   }
 
+  public function getMailDiffSectionHeader() {
+    return pht('CHANGES TO PASTE CONTENT');
+  }
+
   public function newChangeDetailView() {
     $viewer = $this->getViewer();
 

src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php

@@ -1141,9 +1141,15 @@ abstract class PhabricatorApplicationTransactionEditor
     PhabricatorLiskDAO $object,
     array $xactions) {
 
+    $this->object = $object;
+    $this->xactions = $xactions;
+
     // Hook for edges or other properties that may need (re-)loading
     $object = $this->willPublish($object, $xactions);
 
+    // The object might have changed, so reassign it.
+    $this->object = $object;
+
     $messages = array();
     if (!$this->getDisableEmail()) {
       if ($this->shouldSendMail($object, $xactions)) {
@@ -2871,12 +2877,24 @@ abstract class PhabricatorApplicationTransactionEditor
     foreach ($details as $xaction) {
       $details = $xaction->renderChangeDetailsForMail($body->getViewer());
       if ($details !== null) {
-        $body->addHTMLSection(pht('EDIT DETAILS'), $details);
+        $label = $this->getMailDiffSectionHeader($xaction);
+        $body->addHTMLSection($label, $details);
       }
     }
 
   }
 
+  private function getMailDiffSectionHeader($xaction) {
+    $type = $xaction->getTransactionType();
+
+    $xtype = $this->getModularTransactionType($type);
+    if ($xtype) {
+      return $xtype->getMailDiffSectionHeader();
+    }
+
+    return pht('EDIT DETAILS');
+  }
+
   /**
    * @task mail
    */

src/applications/transactions/storage/PhabricatorModularTransactionType.php

@@ -67,6 +67,10 @@ abstract class PhabricatorModularTransactionType
     throw new PhutilMethodNotImplementedException();
   }
 
+  public function getMailDiffSectionHeader() {
+    return pht('EDIT DETAILS');
+  }
+
   public function newRemarkupChanges() {
     return array();
   }