Allow construction of ApplicationSearch queries with GET

Summary:
Ref T3775 (discussion here). Ref T2625.

T3775 presents two problems:

  # Existing tools which linked to `/differential/active/epriestley/` (that is, put a username in the URL) can't generate search links now.
  # Humans can't edit the URL anymore, either.

I think (1) is an actual issue, and this fixes it. I think (2) is pretty fluff, and this doesn't really try to fix it, although it probably improves it.

The fix for (1) is:

  - Provide a helper to read a parameter containing either a list of user PHIDs or a list of usernames, so `/?users[]=PHID-USER-xyz` (from a tokenizer) and `/?users=alincoln,htaft` (from an external program) are equivalent inputs.
  - Rename all the form parameters to be more digestable (`authorPHIDs` -> `authors`). Almost all of them were in this form already anyway. This just gives us `?users=alincoln` instead of `userPHIDs=alincoln`.
  - Inside ApplicationSearch, if a request has no query associated with it but does have query parameters, build a query from the request instead of issuing the user's default query. Basically, this means that `/differential/` runs the default query, while `/differential/?users=x` runs a custom query.

Test Plan: {F56612}

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2625, T3775

Differential Revision: https://secure.phabricator.com/D6840

src/applications/search/controller/PhabricatorApplicationSearchController.php

@@ -107,7 +107,15 @@ final class PhabricatorApplicationSearchController
       $run_query = false;
       $query_key = $request->getStr('query');
     } else if (!strlen($this->queryKey)) {
-      $query_key = head_key($engine->loadEnabledNamedQueries());
+      if ($request->isHTTPGet() && $request->getPassthroughRequestData()) {
+        // If this is a GET request and it has some query data, don't
+        // do anything. We'll build and execute a query from it below.
+        // This allows external tools to build URIs like "/query/?users=a,b".
+      } else {
+        // Otherwise, there's no query data so just run the user's default
+        // query for this application.
+        $query_key = head_key($engine->loadEnabledNamedQueries());
+      }
     }
 
     if ($engine->isBuiltinQuery($query_key)) {

src/applications/search/engine/PhabricatorApplicationSearchEngine.php

@@ -7,6 +7,7 @@
  * @task builtin  Builtin Queries
  * @task uri      Query URIs
  * @task dates    Date Filters
+ * @task read     Reading Utilities
  *
  * @group search
  */
@@ -234,6 +235,60 @@ abstract class PhabricatorApplicationSearchEngine {
   }
 
 
+/* -(  Reading Utilities )--------------------------------------------------- */
+
+
+  /**
+   * Read a list of user PHIDs from a request in a flexible way. This method
+   * supports either of these forms:
+   *
+   *   users[]=alincoln&users[]=htaft
+   *   users=alincoln,htaft
+   *
+   * Additionally, users can be specified either by PHID or by name.
+   *
+   * The main goal of this flexibility is to allow external programs to generate
+   * links to pages (like "alincoln's open revisions") without needing to make
+   * API calls.
+   *
+   * @param AphrontRequest  Request to read user PHIDs from.
+   * @param string          Key to read in the request.
+   * @return list<phid>     List of user PHIDs.
+   *
+   * @task read
+   */
+  protected function readUsersFromRequest(AphrontRequest $request, $key) {
+    $list = $request->getArr($key, null);
+    if ($list === null) {
+      $list = $request->getStrList($key);
+    }
+
+    $phids = array();
+    $names = array();
+    $user_type = PhabricatorPHIDConstants::PHID_TYPE_USER;
+    foreach ($list as $item) {
+      if (phid_get_type($item) == $user_type) {
+        $phids[] = $item;
+      } else {
+        $names[] = $item;
+      }
+    }
+
+    if ($names) {
+      $users = id(new PhabricatorPeopleQuery())
+        ->setViewer($this->requireViewer())
+        ->withUsernames($names)
+        ->execute();
+      foreach ($users as $user) {
+        $phids[] = $user->getPHID();
+      }
+      $phids = array_unique($phids);
+    }
+
+    return $phids;
+  }
+
+
 /* -(  Dates  )-------------------------------------------------------------- */