From 43112b60dafed83fe8ceb948614fcb5662aa4b4d Mon Sep 17 00:00:00 2001
From: =?utf8?q?Gerg=C5=91=20Tisza?= <gtisza@wikimedia.org>
Date: Wed, 27 Jul 2016 01:44:53 +0000
Subject: [PATCH] Add User::findUsersByGroup()

Needed by Iee6e0074d64.

Change-Id: Idbaf2102410f82343ad38ff51ccb7ab70b15e654
---
 includes/user/User.php                   | 38 ++++++++++++++++++++++++
 tests/phpunit/includes/user/UserTest.php | 33 ++++++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/includes/user/User.php b/includes/user/User.php
index a774aba4d9..39507af97a 100644
--- a/includes/user/User.php
+++ b/includes/user/User.php
@@ -911,6 +911,44 @@ class User implements IDBAccessObject {
 		return true;
 	}
 
+	/**
+	 * Return the users who are members of the given group(s). In case of multiple groups,
+	 * users who are members of at least one of them are returned.
+	 *
+	 * @param string|array $groups A single group name or an array of group names
+	 * @param int $limit Max number of users to return. The actual limit will never exceed 5000
+	 *   records; larger values are ignored.
+	 * @param int $after ID the user to start after
+	 * @return UserArrayFromResult
+	 */
+	public static function findUsersByGroup( $groups, $limit = 5000, $after = null ) {
+		if ( $groups === [] ) {
+			return UserArrayFromResult::newFromIDs( [] );
+		}
+
+		$groups = array_unique( (array)$groups );
+		$limit = min( 5000, $limit );
+
+		$conds = [ 'ug_group' => $groups ];
+		if ( $after !== null ) {
+			$conds[] = 'ug_user > ' . (int)$after;
+		}
+
+		$dbr = wfGetDB( DB_SLAVE );
+		$ids = $dbr->selectFieldValues(
+			'user_groups',
+			'ug_user',
+			$conds,
+			__METHOD__,
+			[
+				'DISTINCT' => true,
+				'ORDER BY' => 'ug_user',
+				'LIMIT' => $limit,
+			]
+		) ?: [];
+		return UserArray::newFromIDs( $ids );
+	}
+
 	/**
 	 * Usernames which fail to pass this function will be blocked
 	 * from new account registrations, but may be used internally
diff --git a/tests/phpunit/includes/user/UserTest.php b/tests/phpunit/includes/user/UserTest.php
index 801ab9179b..beb5e78259 100644
--- a/tests/phpunit/includes/user/UserTest.php
+++ b/tests/phpunit/includes/user/UserTest.php
@@ -451,4 +451,37 @@ class UserTest extends MediaWikiTestCase {
 		$this->assertGreaterThan(
 			$touched, $user->getDBTouched(), "user_touched increased with casOnTouched() #2" );
 	}
+
+	/**
+	 * @covers User::findUsersByGroup
+	 */
+	public function testFindUsersByGroup() {
+		$users = User::findUsersByGroup( [] );
+		$this->assertEquals( 0, iterator_count( $users ) );
+
+		$users = User::findUsersByGroup( 'foo' );
+		$this->assertEquals( 0, iterator_count( $users ) );
+
+		$user = $this->getMutableTestUser( [ 'foo' ] )->getUser();
+		$users = User::findUsersByGroup( 'foo' );
+		$this->assertEquals( 1, iterator_count( $users ) );
+		$users->rewind();
+		$this->assertTrue( $user->equals( $users->current() ) );
+
+		// arguments have OR relationship
+		$user2 = $this->getMutableTestUser( [ 'bar' ] )->getUser();
+		$users = User::findUsersByGroup( [ 'foo', 'bar' ] );
+		$this->assertEquals( 2, iterator_count( $users ) );
+		$users->rewind();
+		$this->assertTrue( $user->equals( $users->current() ) );
+		$users->next();
+		$this->assertTrue( $user2->equals( $users->current() ) );
+
+		// users are not duplicated
+		$user = $this->getMutableTestUser( [ 'baz', 'boom' ] )->getUser();
+		$users = User::findUsersByGroup( [ 'baz', 'boom' ] );
+		$this->assertEquals( 1, iterator_count( $users ) );
+		$users->rewind();
+		$this->assertTrue( $user->equals( $users->current() ) );
+	}
 }
-- 
2.20.1