Add a "Create Subtask" operation to Maniphest

Summary:
Add a new "Create Subtask" action that allows you to quickly split a task into
dependent subtasks, using the parent task as a template.

Followups:

  - Cause "workflow=<parent>" to change "Create Another Task" into "Create
Another Subtask" (after D736).
  - Show parent tasks (requires some schema stuff).

Test Plan:
  - Created a new task.
  - Created a new subtask.

Reviewed By: codeblock
Reviewers: hunterbridges, codeblock, jungejason, tuomaspelkonen, aran
CC: aran, codeblock
Differential Revision: 774

src/applications/maniphest/controller/taskdetail/ManiphestTaskDetailController.php

@@ -220,6 +220,13 @@ class ManiphestTaskDetailController extends ManiphestController {
     $action->setClass('action-merge');
     $actions[] = $action;
 
+    $action = new AphrontHeadsupActionView();
+    $action->setName('Create Subtask');
+    $action->setURI('/maniphest/task/create/?parent='.$task->getID());
+    $action->setClass('action-branch');
+    $actions[] = $action;
+
+
     $action = new AphrontHeadsupActionView();
     $action->setName('Edit Dependencies');
     $action->setURI('/search/attach/'.$task->getPHID().'/TASK/dependencies/');

src/applications/maniphest/controller/taskedit/ManiphestTaskEditController.php

@@ -33,6 +33,8 @@ class ManiphestTaskEditController extends ManiphestController {
     $user = $request->getUser();
 
     $files = array();
+    $parent_task = null;
+    $template_id = null;
 
     if ($this->id) {
       $task = id(new ManiphestTask())->load($this->id);
@@ -70,9 +72,15 @@ class ManiphestTaskEditController extends ManiphestController {
           'phid IN (%Ls)',
           $file_phids);
       }
-    }
 
-    $template_id = $request->getStr('template');
+      $template_id = $request->getInt('template');
+
+      // You can only have a parent task if you're creating a new task.
+      $parent_id = $request->getInt('parent');
+      if ($parent_id) {
+        $parent_task = id(new ManiphestTask())->load($parent_id);
+      }
+    }
 
     $errors = array();
     $e_title = true;
@@ -198,6 +206,25 @@ class ManiphestTaskEditController extends ManiphestController {
           );
         }
 
+        if ($parent_task) {
+          $type_task = PhabricatorPHIDConstants::PHID_TYPE_TASK;
+
+          // NOTE: It's safe to simply apply this transaction without doing
+          // cycle detection because we know the new task has no children.
+          $new_value = $parent_task->getAttached();
+          $new_value[$type_task][$task->getPHID()] = true;
+
+          $parent_xaction = clone $template;
+          $attach_type = ManiphestTransactionType::TYPE_ATTACH;
+          $parent_xaction->setTransactionType($attach_type);
+          $parent_xaction->setNewValue($new_value);
+
+          $editor = new ManiphestTransactionEditor();
+          $editor->applyTransactions($parent_task, array($parent_xaction));
+
+          $workflow = $parent_task->getID();
+        }
+
         $redirect_uri = '/T'.$task->getID();
 
         if ($workflow) {
@@ -228,6 +255,10 @@ class ManiphestTaskEditController extends ManiphestController {
       $task->getCCPHIDs(),
       $task->getProjectPHIDs());
 
+    if ($parent_task) {
+      $phids[] = $parent_task->getPHID();
+    }
+
     $phids = array_filter($phids);
     $phids = array_unique($phids);
 
@@ -275,6 +306,10 @@ class ManiphestTaskEditController extends ManiphestController {
     if ($task->getID()) {
       $button_name = 'Save Task';
       $header_name = 'Edit Task';
+    } else if ($parent_task) {
+      $cancel_uri = '/T'.$parent_task->getID();
+      $button_name = 'Create Task';
+      $header_name = 'Create New Subtask';
     } else {
       $button_name = 'Create Task';
       $header_name = 'Create New Task';
@@ -286,7 +321,18 @@ class ManiphestTaskEditController extends ManiphestController {
     $form
       ->setUser($user)
       ->setAction($request->getRequestURI()->getPath())
-      ->addHiddenInput('template', $template_id)
+      ->addHiddenInput('template', $template_id);
+
+    if ($parent_task) {
+      $form
+        ->appendChild(
+          id(new AphrontFormStaticControl())
+            ->setLabel('Parent Task')
+            ->setValue($handles[$parent_task->getPHID()]->getFullName()))
+        ->addHiddenInput('parent', $parent_task->getID());
+    }
+
+    $form
       ->appendChild(
         id(new AphrontFormTextAreaControl())
           ->setLabel('Title')

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

@@ -26,6 +26,7 @@ phutil_require_module('phabricator', 'infrastructure/javelin/markup');
 phutil_require_module('phabricator', 'view/form/base');
 phutil_require_module('phabricator', 'view/form/control/markup');
 phutil_require_module('phabricator', 'view/form/control/select');
+phutil_require_module('phabricator', 'view/form/control/static');
 phutil_require_module('phabricator', 'view/form/control/submit');
 phutil_require_module('phabricator', 'view/form/control/textarea');
 phutil_require_module('phabricator', 'view/form/control/tokenizer');

webroot/rsrc/css/aphront/headsup-action-list-view.css

@@ -66,6 +66,10 @@
   background-image: url(/rsrc/image/icon/fatcow/arrow_merge.png);
 }
 
+.aphront-headsup-action-list .action-branch {
+  background-image: url(/rsrc/image/icon/fatcow/arrow_branch.png);
+}
+
 .aphront-headsup-action-list .action-dependencies {
   background-image: url(/rsrc/image/icon/fatcow/link.png);
 }