Implement readProjectsFromRequest() helper for SearchEngines

Summary:
Ref T4100. This just makes the "specify stuff in query parameters" workflow a little better:

  - You can now do `?projects=differential,diffusion`.
  - You can now do `?projects=projects(alincoln)`.

Test Plan: Did that stuff ^^^^

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4100

Differential Revision: https://secure.phabricator.com/D12468

src/applications/differential/query/DifferentialRevisionSearchEngine.php

@@ -40,16 +40,15 @@ final class DifferentialRevisionSearchEngine
 
     $saved->setParameter(
       'subscriberPHIDs',
-      $this->readUsersFromRequest($request, 'subscribers'));
+      $this->readSubscribersFromRequest($request, 'subscribers'));
 
     $saved->setParameter(
       'repositoryPHIDs',
       $request->getArr('repositories'));
 
-    // TODO: Implement "readProjectsFromRequest(...)" to improve this.
     $saved->setParameter(
       'projects',
-      $this->readListFromRequest($request, 'projects'));
+      $this->readProjectsFromRequest($request, 'projects'));
 
     $saved->setParameter(
       'draft',

src/applications/phid/PhabricatorPHIDConstants.php

@@ -2,7 +2,6 @@
 
 final class PhabricatorPHIDConstants {
 
-  const PHID_TYPE_USER    = 'USER';
   const PHID_TYPE_UNKNOWN = '????';
   const PHID_TYPE_MAGIC   = '!!!!';
   const PHID_TYPE_STRY    = 'STRY';

src/applications/project/typeahead/PhabricatorProjectLogicalUserDatasource.php

@@ -44,6 +44,8 @@ final class PhabricatorProjectLogicalUserDatasource
       $phids[] = head($argv);
     }
 
+    $phids = $this->resolvePHIDs($phids);
+
     $projects = id(new PhabricatorProjectQuery())
       ->setViewer($this->getViewer())
       ->withMemberPHIDs($phids)
@@ -65,6 +67,8 @@ final class PhabricatorProjectLogicalUserDatasource
       $phids[] = head($argv);
     }
 
+    $phids = $this->resolvePHIDs($phids);
+
     $tokens = $this->renderTokens($phids);
     foreach ($tokens as $token) {
       if ($token->isInvalid()) {
@@ -82,4 +86,38 @@ final class PhabricatorProjectLogicalUserDatasource
     return $tokens;
   }
 
+  private function resolvePHIDs(array $phids) {
+    // If we have a function like `projects(alincoln)`, try to resolve the
+    // username first. This won't happen normally, but can be passed in from
+    // the query string.
+
+    // The user might also give us an invalid username. In this case, we
+    // preserve it and return it in-place so we get an "invalid" token rendered
+    // in the UI. This shows the user where the issue is and  best represents
+    // the user's input.
+
+    $usernames = array();
+    foreach ($phids as $key => $phid) {
+      if (phid_get_type($phid) != PhabricatorPeopleUserPHIDType::TYPECONST) {
+        $usernames[$key] = $phid;
+      }
+    }
+
+    if ($usernames) {
+      $users = id(new PhabricatorPeopleQuery())
+        ->setViewer($this->getViewer())
+        ->withUsernames($usernames)
+        ->execute();
+      $users = mpull($users, null, 'getUsername');
+      foreach ($usernames as $key => $username) {
+        $user = idx($users, $username);
+        if ($user) {
+          $phids[$key] = $user->getPHID();
+        }
+      }
+    }
+
+    return $phids;
+  }
+
 }

src/applications/search/engine/PhabricatorApplicationSearchEngine.php

@@ -378,8 +378,7 @@ abstract class PhabricatorApplicationSearchEngine {
    * @param AphrontRequest  Request to read user PHIDs from.
    * @param string          Key to read in the request.
    * @param list<const>     Other permitted PHID types.
-   * @return list<phid>     List of user PHIDs.
-   *
+   * @return list<phid>     List of user PHIDs and selector functions.
    * @task read
    */
   protected function readUsersFromRequest(
@@ -392,7 +391,7 @@ abstract class PhabricatorApplicationSearchEngine {
     $phids = array();
     $names = array();
     $allow_types = array_fuse($allow_types);
-    $user_type = PhabricatorPHIDConstants::PHID_TYPE_USER;
+    $user_type = PhabricatorPeopleUserPHIDType::TYPECONST;
     foreach ($list as $item) {
       $type = phid_get_type($item);
       if ($type == $user_type) {
@@ -425,6 +424,71 @@ abstract class PhabricatorApplicationSearchEngine {
   }
 
 
+  /**
+   * Read a list of project PHIDs from a request in a flexible way.
+   *
+   * @param AphrontRequest  Request to read user PHIDs from.
+   * @param string          Key to read in the request.
+   * @return list<phid>     List of projet PHIDs and selector functions.
+   * @task read
+   */
+  protected function readProjectsFromRequest(AphrontRequest $request, $key) {
+    $list = $this->readListFromRequest($request, $key);
+
+    $phids = array();
+    $slugs = array();
+    $project_type = PhabricatorProjectProjectPHIDType::TYPECONST;
+    foreach ($list as $item) {
+      $type = phid_get_type($item);
+      if ($type == $project_type) {
+        $phids[] = $item;
+      } else {
+        if (PhabricatorTypeaheadDatasource::isFunctionToken($item)) {
+          // If this is a function, pass it through unchanged; we'll evaluate
+          // it later.
+          $phids[] = $item;
+        } else {
+          $slugs[] = $item;
+        }
+      }
+    }
+
+    if ($slugs) {
+      $projects = id(new PhabricatorProjectQuery())
+        ->setViewer($this->requireViewer())
+        ->withSlugs($slugs)
+        ->execute();
+      foreach ($projects as $project) {
+        $phids[] = $project->getPHID();
+      }
+      $phids = array_unique($phids);
+    }
+
+    return $phids;
+  }
+
+
+  /**
+   * Read a list of subscribers from a request in a flexible way.
+   *
+   * @param AphrontRequest  Request to read PHIDs from.
+   * @param string          Key to read in the request.
+   * @return list<phid>     List of object PHIDs.
+   * @task read
+   */
+  protected function readSubscribersFromRequest(
+    AphrontRequest $request,
+    $key) {
+    return $this->readUsersFromRequest(
+      $request,
+      $key,
+      array(
+        PhabricatorProjectProjectPHIDType::TYPECONST,
+        PhabricatorMailingListListPHIDType::TYPECONST,
+      ));
+  }
+
+
   /**
    * Read a list of generic PHIDs from a request in a flexible way. Like
    * @{method:readUsersFromRequest}, this method supports either array or