Allow unsubscription from projects

Summary:
Fixes T4379. Several changes:

  - Migrate all project members into subscribers.
  - When members are added or removed, subscribe or unsubscribe them.
  - Show sub/unsub in the UI.
  - Determine mailable membership of projects by querying subscribers.

Test Plan:
  - As `duck`, joined a project.
  - Added the project as a reviewer to a revision.
  - Commented on the revision.
  - Observed `duck` receive mail.
  - Unsubscribed as `duck`.
  - Observed no mail.
  - Resubscribed as `duck`.
  - Mail again.
  - Joined/left project, checked sub/unsub status.
  - Ran migration, looked at database.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, asherkin

Maniphest Tasks: T4379

Differential Revision: https://secure.phabricator.com/D8189

resources/sql/autopatches/20140210.projcfield.4.memmig.sql

@@ -0,0 +1,8 @@
+/* These are here so `grep` will find them if we ever change things: */
+
+/* PhabricatorEdgeConfig::TYPE_PROJ_MEMBER = 13 */
+/* PhabricatorEdgeConfig::TYPE_OBJECT_HAS_SUBSCRIBER = 21 */
+
+INSERT IGNORE INTO {$NAMESPACE}_project.edge (src, type, dst, dateCreated)
+  SELECT src, 21, dst, dateCreated FROM {$NAMESPACE}_project.edge
+    WHERE type = 13;

src/applications/metamta/query/PhabricatorMetaMTAMemberQuery.php

@@ -37,24 +37,24 @@ final class PhabricatorMetaMTAMemberQuery extends PhabricatorQuery {
     foreach ($type_map as $type => $phids) {
       switch ($type) {
         case PhabricatorProjectPHIDTypeProject::TYPECONST:
-          // TODO: For now, project members are always on the "mailing list"
-          // implied by the project, but we should differentiate members and
-          // subscribers (i.e., allow you to unsubscribe from mail about
-          // a project).
+          // NOTE: We're loading the projects here in order to respect policies.
 
           $projects = id(new PhabricatorProjectQuery())
             ->setViewer($this->getViewer())
-            ->needMembers(true)
             ->withPHIDs($phids)
             ->execute();
 
+          $subscribers = id(new PhabricatorSubscribersQuery())
+            ->withObjectPHIDs($phids)
+            ->execute();
+
           $projects = mpull($projects, null, 'getPHID');
           foreach ($phids as $phid) {
             $project = idx($projects, $phid);
             if (!$project) {
               $results[$phid] = array();
             } else {
-              $results[$phid] = $project->getMemberPHIDs();
+              $results[$phid] = idx($subscribers, $phid, array());
             }
           }
           break;

src/applications/project/editor/PhabricatorProjectTransactionEditor.php

@@ -118,10 +118,36 @@ final class PhabricatorProjectTransactionEditor
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
-      case PhabricatorTransactions::TYPE_EDGE:
       case PhabricatorProjectTransaction::TYPE_STATUS:
       case PhabricatorProjectTransaction::TYPE_IMAGE:
         return;
+      case PhabricatorTransactions::TYPE_EDGE:
+        switch ($xaction->getMetadataValue('edge:type')) {
+          case PhabricatorEdgeConfig::TYPE_PROJ_MEMBER:
+            // When project members are added or removed, add or remove their
+            // subscriptions.
+            $old = $xaction->getOldValue();
+            $new = $xaction->getNewValue();
+            $add = array_keys(array_diff_key($new, $old));
+            $rem = array_keys(array_diff_key($old, $new));
+
+            // NOTE: The subscribe is "explicit" because there's no implicit
+            // unsubscribe, so Join -> Leave -> Join doesn't resubscribe you
+            // if we use an implicit subscribe, even though you never willfully
+            // unsubscribed. Not sure if adding implicit unsubscribe (which
+            // would not write the unsubscribe row) is justified to deal with
+            // this, which is a fairly weird edge case and pretty arguable both
+            // ways.
+
+            id(new PhabricatorSubscriptionsEditor())
+              ->setActor($this->requireActor())
+              ->setObject($object)
+              ->subscribeExplicit($add)
+              ->unsubscribe($rem)
+              ->save();
+            break;
+        }
+        return;
     }
 
     return parent::applyCustomExternalTransaction($object, $xaction);

src/applications/project/storage/PhabricatorProject.php

@@ -171,7 +171,7 @@ final class PhabricatorProject extends PhabricatorProjectDAO
   }
 
   public function shouldAllowSubscription($phid) {
-    return false;
+    return $this->isUserMember($phid);
   }