rcfeed: Add basic PHPUnit integration test

[mediawiki.git] / includes / specials / SpecialUserrights.php

<?php
/**
 * Implements Special:Userrights
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup SpecialPage
 */

/**
 * Special page to allow managing user group membership
 *
 * @ingroup SpecialPage
 */
class UserrightsPage extends SpecialPage {
        /**
         * The target of the local right-adjuster's interest.  Can be gotten from
         * either a GET parameter or a subpage-style parameter, so have a member
         * variable for it.
         * @var null|string $mTarget
         */
        protected $mTarget;
        /*
         * @var null|User $mFetchedUser The user object of the target username or null.
         */
        protected $mFetchedUser = null;
        protected $isself = false;

        public function __construct() {
                parent::__construct( 'Userrights' );
        }

        public function doesWrites() {
                return true;
        }

        /**
         * Check whether the current user (from context) can change the target user's rights.
         *
         * @param User $targetUser User whose rights are being changed
         * @param bool $checkIfSelf If false, assume that the current user can add/remove groups defined
         *   in $wgGroupsAddToSelf / $wgGroupsRemoveFromSelf, without checking if it's the same as target
         *   user
         * @return bool
         */
        public function userCanChangeRights( $targetUser, $checkIfSelf = true ) {
                $isself = $this->getUser()->equals( $targetUser );

                $available = $this->changeableGroups();
                if ( $targetUser->getId() == 0 ) {
                        return false;
                }

                return !empty( $available['add'] )
                        || !empty( $available['remove'] )
                        || ( ( $isself || !$checkIfSelf ) &&
                                ( !empty( $available['add-self'] )
                                        || !empty( $available['remove-self'] ) ) );
        }

        /**
         * Manage forms to be shown according to posted data.
         * Depending on the submit button used, call a form or a save function.
         *
         * @param string|null $par String if any subpage provided, else null
         * @throws UserBlockedError|PermissionsError
         */
        public function execute( $par ) {
                $user = $this->getUser();
                $request = $this->getRequest();
                $session = $request->getSession();
                $out = $this->getOutput();

                if ( $par !== null ) {
                        $this->mTarget = $par;
                } else {
                        $this->mTarget = $request->getVal( 'user' );
                }

                if ( is_string( $this->mTarget ) ) {
                        $this->mTarget = trim( $this->mTarget );
                }

                if ( $this->mTarget !== null && User::getCanonicalName( $this->mTarget ) === $user->getName() ) {
                        $this->isself = true;
                }

                $fetchedStatus = $this->fetchUser( $this->mTarget, true );
                if ( $fetchedStatus->isOK() ) {
                        $this->mFetchedUser = $fetchedStatus->value;
                        if ( $this->mFetchedUser instanceof User ) {
                                // Set the 'relevant user' in the skin, so it displays links like Contributions,
                                // User logs, UserRights, etc.
                                $this->getSkin()->setRelevantUser( $this->mFetchedUser );
                        }
                }

                // show a successbox, if the user rights was saved successfully
                if (
                        $session->get( 'specialUserrightsSaveSuccess' ) &&
                        $this->mFetchedUser !== null
                ) {
                        // Remove session data for the success message
                        $session->remove( 'specialUserrightsSaveSuccess' );

                        $out->addModules( [ 'mediawiki.special.userrights' ] );
                        $out->addModuleStyles( 'mediawiki.notification.convertmessagebox.styles' );
                        $out->addHTML(
                                Html::rawElement(
                                        'div',
                                        [
                                                'class' => 'mw-notify-success successbox',
                                                'id' => 'mw-preferences-success',
                                                'data-mw-autohide' => 'false',
                                        ],
                                        Html::element(
                                                'p',
                                                [],
                                                $this->msg( 'savedrights', $this->mFetchedUser->getName() )->text()
                                        )
                                )
                        );
                }

                $this->setHeaders();
                $this->outputHeader();

                $out->addModuleStyles( 'mediawiki.special' );
                $this->addHelpLink( 'Help:Assigning permissions' );

                $this->switchForm();

                if (
                        $request->wasPosted() &&
                        $request->getCheck( 'saveusergroups' ) &&
                        $this->mTarget !== null &&
                        $user->matchEditToken( $request->getVal( 'wpEditToken' ), $this->mTarget )
                ) {
                        /*
                        * If the user is blocked and they only have "partial" access
                        * (e.g. they don't have the userrights permission), then don't
                        * allow them to change any user rights.
                        */
                        if ( $user->isBlocked() && !$user->isAllowed( 'userrights' ) ) {
                                throw new UserBlockedError( $user->getBlock() );
                        }

                        $this->checkReadOnly();

                        // save settings
                        if ( !$fetchedStatus->isOK() ) {
                                $this->getOutput()->addWikiText( $fetchedStatus->getWikiText() );

                                return;
                        }

                        $targetUser = $this->mFetchedUser;
                        if ( $targetUser instanceof User ) { // UserRightsProxy doesn't have this method (bug 61252)
                                $targetUser->clearInstanceCache(); // bug 38989
                        }

                        if ( $request->getVal( 'conflictcheck-originalgroups' )
                                !== implode( ',', $targetUser->getGroups() )
                        ) {
                                $out->addWikiMsg( 'userrights-conflict' );
                        } else {
                                $this->saveUserGroups(
                                        $this->mTarget,
                                        $request->getVal( 'user-reason' ),
                                        $targetUser
                                );

                                // Set session data for the success message
                                $session->set( 'specialUserrightsSaveSuccess', 1 );

                                $out->redirect( $this->getSuccessURL() );

                                return;
                        }
                }

                // show some more forms
                if ( $this->mTarget !== null ) {
                        $this->editUserGroupsForm( $this->mTarget );
                }
        }

        function getSuccessURL() {
                return $this->getPageTitle( $this->mTarget )->getFullURL();
        }

        /**
         * Save user groups changes in the database.
         * Data comes from the editUserGroupsForm() form function
         *
         * @param string $username Username to apply changes to.
         * @param string $reason Reason for group change
         * @param User|UserRightsProxy $user Target user object.
         * @return null
         */
        function saveUserGroups( $username, $reason, $user ) {
                $allgroups = $this->getAllGroups();
                $addgroup = [];
                $removegroup = [];

                // This could possibly create a highly unlikely race condition if permissions are changed between
                //  when the form is loaded and when the form is saved. Ignoring it for the moment.
                foreach ( $allgroups as $group ) {
                        // We'll tell it to remove all unchecked groups, and add all checked groups.
                        // Later on, this gets filtered for what can actually be removed
                        if ( $this->getRequest()->getCheck( "wpGroup-$group" ) ) {
                                $addgroup[] = $group;
                        } else {
                                $removegroup[] = $group;
                        }
                }

                $this->doSaveUserGroups( $user, $addgroup, $removegroup, $reason );
        }

        /**
         * Save user groups changes in the database.
         *
         * @param User|UserRightsProxy $user
         * @param array $add Array of groups to add
         * @param array $remove Array of groups to remove
         * @param string $reason Reason for group change
         * @param array $tags Array of change tags to add to the log entry
         * @return array Tuple of added, then removed groups
         */
        function doSaveUserGroups( $user, $add, $remove, $reason = '', $tags = [] ) {
                // Validate input set...
                $isself = $user->getName() == $this->getUser()->getName();
                $groups = $user->getGroups();
                $changeable = $this->changeableGroups();
                $addable = array_merge( $changeable['add'], $isself ? $changeable['add-self'] : [] );
                $removable = array_merge( $changeable['remove'], $isself ? $changeable['remove-self'] : [] );

                $remove = array_unique(
                        array_intersect( (array)$remove, $removable, $groups ) );
                $add = array_unique( array_diff(
                        array_intersect( (array)$add, $addable ),
                        $groups )
                );

                Hooks::run( 'ChangeUserGroups', [ $this->getUser(), $user, &$add, &$remove ] );

                $oldGroups = $user->getGroups();
                $newGroups = $oldGroups;

                // Remove then add groups
                if ( $remove ) {
                        foreach ( $remove as $index => $group ) {
                                if ( !$user->removeGroup( $group ) ) {
                                        unset( $remove[$index] );
                                }
                        }
                        $newGroups = array_diff( $newGroups, $remove );
                }
                if ( $add ) {
                        foreach ( $add as $index => $group ) {
                                if ( !$user->addGroup( $group ) ) {
                                        unset( $add[$index] );
                                }
                        }
                        $newGroups = array_merge( $newGroups, $add );
                }
                $newGroups = array_unique( $newGroups );

                // Ensure that caches are cleared
                $user->invalidateCache();

                // update groups in external authentication database
                Hooks::run( 'UserGroupsChanged', [ $user, $add, $remove, $this->getUser(), $reason ] );
                MediaWiki\Auth\AuthManager::callLegacyAuthPlugin(
                        'updateExternalDBGroups', [ $user, $add, $remove ]
                );

                wfDebug( 'oldGroups: ' . print_r( $oldGroups, true ) . "\n" );
                wfDebug( 'newGroups: ' . print_r( $newGroups, true ) . "\n" );
                // Deprecated in favor of UserGroupsChanged hook
                Hooks::run( 'UserRights', [ &$user, $add, $remove ], '1.26' );

                if ( $newGroups != $oldGroups ) {
                        $this->addLogEntry( $user, $oldGroups, $newGroups, $reason, $tags );
                }

                return [ $add, $remove ];
        }

        /**
         * Add a rights log entry for an action.
         * @param User $user
         * @param array $oldGroups
         * @param array $newGroups
         * @param array $reason
         * @param array $tags
         */
        function addLogEntry( $user, $oldGroups, $newGroups, $reason, $tags ) {
                $logEntry = new ManualLogEntry( 'rights', 'rights' );
                $logEntry->setPerformer( $this->getUser() );
                $logEntry->setTarget( $user->getUserPage() );
                $logEntry->setComment( $reason );
                $logEntry->setParameters( [
                        '4::oldgroups' => $oldGroups,
                        '5::newgroups' => $newGroups,
                ] );
                $logid = $logEntry->insert();
                if ( count( $tags ) ) {
                        $logEntry->setTags( $tags );
                }
                $logEntry->publish( $logid );
        }

        /**
         * Edit user groups membership
         * @param string $username Name of the user.
         */
        function editUserGroupsForm( $username ) {
                $status = $this->fetchUser( $username, true );
                if ( !$status->isOK() ) {
                        $this->getOutput()->addWikiText( $status->getWikiText() );

                        return;
                } else {
                        $user = $status->value;
                }

                $groups = $user->getGroups();

                $this->showEditUserGroupsForm( $user, $groups );

                // This isn't really ideal logging behavior, but let's not hide the
                // interwiki logs if we're using them as is.
                $this->showLogFragment( $user, $this->getOutput() );
        }

        /**
         * Normalize the input username, which may be local or remote, and
         * return a user (or proxy) object for manipulating it.
         *
         * Side effects: error output for invalid access
         * @param string $username
         * @param bool $writing
         * @return Status
         */
        public function fetchUser( $username, $writing = true ) {
                $parts = explode( $this->getConfig()->get( 'UserrightsInterwikiDelimiter' ), $username );
                if ( count( $parts ) < 2 ) {
                        $name = trim( $username );
                        $database = '';
                } else {
                        list( $name, $database ) = array_map( 'trim', $parts );

                        if ( $database == wfWikiID() ) {
                                $database = '';
                        } else {
                                if ( $writing && !$this->getUser()->isAllowed( 'userrights-interwiki' ) ) {
                                        return Status::newFatal( 'userrights-no-interwiki' );
                                }
                                if ( !UserRightsProxy::validDatabase( $database ) ) {
                                        return Status::newFatal( 'userrights-nodatabase', $database );
                                }
                        }
                }

                if ( $name === '' ) {
                        return Status::newFatal( 'nouserspecified' );
                }

                if ( $name[0] == '#' ) {
                        // Numeric ID can be specified...
                        // We'll do a lookup for the name internally.
                        $id = intval( substr( $name, 1 ) );

                        if ( $database == '' ) {
                                $name = User::whoIs( $id );
                        } else {
                                $name = UserRightsProxy::whoIs( $database, $id );
                        }

                        if ( !$name ) {
                                return Status::newFatal( 'noname' );
                        }
                } else {
                        $name = User::getCanonicalName( $name );
                        if ( $name === false ) {
                                // invalid name
                                return Status::newFatal( 'nosuchusershort', $username );
                        }
                }

                if ( $database == '' ) {
                        $user = User::newFromName( $name );
                } else {
                        $user = UserRightsProxy::newFromName( $database, $name );
                }

                if ( !$user || $user->isAnon() ) {
                        return Status::newFatal( 'nosuchusershort', $username );
                }

                return Status::newGood( $user );
        }

        /**
         * @since 1.15
         *
         * @param array $ids
         *
         * @return string
         */
        public function makeGroupNameList( $ids ) {
                if ( empty( $ids ) ) {
                        return $this->msg( 'rightsnone' )->inContentLanguage()->text();
                } else {
                        return implode( ', ', $ids );
                }
        }

        /**
         * Output a form to allow searching for a user
         */
        function switchForm() {
                $this->getOutput()->addModules( 'mediawiki.userSuggest' );

                $this->getOutput()->addHTML(
                        Html::openElement(
                                'form',
                                [
                                        'method' => 'get',
                                        'action' => wfScript(),
                                        'name' => 'uluser',
                                        'id' => 'mw-userrights-form1'
                                ]
                        ) .
                        Html::hidden( 'title', $this->getPageTitle()->getPrefixedText() ) .
                        Xml::fieldset( $this->msg( 'userrights-lookup-user' )->text() ) .
                        Xml::inputLabel(
                                $this->msg( 'userrights-user-editname' )->text(),
                                'user',
                                'username',
                                30,
                                str_replace( '_', ' ', $this->mTarget ),
                                [
                                        'class' => 'mw-autocomplete-user', // used by mediawiki.userSuggest
                                ] + (
                                        // Set autofocus on blank input and error input
                                        $this->mFetchedUser === null ? [ 'autofocus' => '' ] : []
                                )
                        ) . ' ' .
                        Xml::submitButton(
                                $this->msg( 'editusergroup' )->text()
                        ) .
                        Html::closeElement( 'fieldset' ) .
                        Html::closeElement( 'form' ) . "\n"
                );
        }

        /**
         * Show the form to edit group memberships.
         *
         * @param User|UserRightsProxy $user User or UserRightsProxy you're editing
         * @param array $groups Array of groups the user is in
         */
        protected function showEditUserGroupsForm( $user, $groups ) {
                $list = [];
                $membersList = [];
                foreach ( $groups as $group ) {
                        $list[] = self::buildGroupLink( $group );
                        $membersList[] = self::buildGroupMemberLink( $group );
                }

                $autoList = [];
                $autoMembersList = [];
                if ( $user instanceof User ) {
                        foreach ( Autopromote::getAutopromoteGroups( $user ) as $group ) {
                                $autoList[] = self::buildGroupLink( $group );
                                $autoMembersList[] = self::buildGroupMemberLink( $group );
                        }
                }

                $language = $this->getLanguage();
                $displayedList = $this->msg( 'userrights-groupsmember-type' )
                        ->rawParams(
                                $language->listToText( $list ),
                                $language->listToText( $membersList )
                        )->escaped();
                $displayedAutolist = $this->msg( 'userrights-groupsmember-type' )
                        ->rawParams(
                                $language->listToText( $autoList ),
                                $language->listToText( $autoMembersList )
                        )->escaped();

                $grouplist = '';
                $count = count( $list );
                if ( $count > 0 ) {
                        $grouplist = $this->msg( 'userrights-groupsmember' )
                                ->numParams( $count )
                                ->params( $user->getName() )
                                ->parse();
                        $grouplist = '<p>' . $grouplist . ' ' . $displayedList . "</p>\n";
                }

                $count = count( $autoList );
                if ( $count > 0 ) {
                        $autogrouplistintro = $this->msg( 'userrights-groupsmember-auto' )
                                ->numParams( $count )
                                ->params( $user->getName() )
                                ->parse();
                        $grouplist .= '<p>' . $autogrouplistintro . ' ' . $displayedAutolist . "</p>\n";
                }

                $userToolLinks = Linker::userToolLinks(
                        $user->getId(),
                        $user->getName(),
                        false, /* default for redContribsWhenNoEdits */
                        Linker::TOOL_LINKS_EMAIL /* Add "send e-mail" link */
                );

                list( $groupCheckboxes, $canChangeAny ) = $this->groupCheckboxes( $groups, $user );
                $this->getOutput()->addHTML(
                        Xml::openElement(
                                'form',
                                [
                                        'method' => 'post',
                                        'action' => $this->getPageTitle()->getLocalURL(),
                                        'name' => 'editGroup',
                                        'id' => 'mw-userrights-form2'
                                ]
                        ) .
                        Html::hidden( 'user', $this->mTarget ) .
                        Html::hidden( 'wpEditToken', $this->getUser()->getEditToken( $this->mTarget ) ) .
                        Html::hidden(
                                'conflictcheck-originalgroups',
                                implode( ',', $user->getGroups() )
                        ) . // Conflict detection
                        Xml::openElement( 'fieldset' ) .
                        Xml::element(
                                'legend',
                                [],
                                $this->msg(
                                        $canChangeAny ? 'userrights-editusergroup' : 'userrights-viewusergroup',
                                        $user->getName()
                                )->text()
                        ) .
                        $this->msg(
                                $canChangeAny ? 'editinguser' : 'viewinguserrights'
                        )->params( wfEscapeWikiText( $user->getName() ) )
                                ->rawParams( $userToolLinks )->parse()
                );
                if ( $canChangeAny ) {
                        $this->getOutput()->addHTML(
                                $this->msg( 'userrights-groups-help', $user->getName() )->parse() .
                                $grouplist .
                                $groupCheckboxes .
                                Xml::openElement( 'table', [ 'id' => 'mw-userrights-table-outer' ] ) .
                                        "<tr>
                                                <td class='mw-label'>" .
                                                        Xml::label( $this->msg( 'userrights-reason' )->text(), 'wpReason' ) .
                                                "</td>
                                                <td class='mw-input'>" .
                                                        Xml::input( 'user-reason', 60, $this->getRequest()->getVal( 'user-reason', false ),
                                                                [ 'id' => 'wpReason', 'maxlength' => 255 ] ) .
                                                "</td>
                                        </tr>
                                        <tr>
                                                <td></td>
                                                <td class='mw-submit'>" .
                                                        Xml::submitButton( $this->msg( 'saveusergroups', $user->getName() )->text(),
                                                                [ 'name' => 'saveusergroups' ] +
                                                                        Linker::tooltipAndAccesskeyAttribs( 'userrights-set' )
                                                        ) .
                                                "</td>
                                        </tr>" .
                                Xml::closeElement( 'table' ) . "\n"
                        );
                } else {
                        $this->getOutput()->addHTML( $grouplist );
                }
                $this->getOutput()->addHTML(
                        Xml::closeElement( 'fieldset' ) .
                        Xml::closeElement( 'form' ) . "\n"
                );
        }

        /**
         * Format a link to a group description page
         *
         * @param string $group
         * @return string
         */
        private static function buildGroupLink( $group ) {
                return User::makeGroupLinkHTML( $group, User::getGroupName( $group ) );
        }

        /**
         * Format a link to a group member description page
         *
         * @param string $group
         * @return string
         */
        private static function buildGroupMemberLink( $group ) {
                return User::makeGroupLinkHTML( $group, User::getGroupMember( $group ) );
        }

        /**
         * Returns an array of all groups that may be edited
         * @return array Array of groups that may be edited.
         */
        protected static function getAllGroups() {
                return User::getAllGroups();
        }

        /**
         * Adds a table with checkboxes where you can select what groups to add/remove
         *
         * @todo Just pass the username string?
         * @param array $usergroups Groups the user belongs to
         * @param User $user
         * @return Array with 2 elements: the XHTML table element with checkxboes, and
         * whether any groups are changeable
         */
        private function groupCheckboxes( $usergroups, $user ) {
                $allgroups = $this->getAllGroups();
                $ret = '';

                // Put all column info into an associative array so that extensions can
                // more easily manage it.
                $columns = [ 'unchangeable' => [], 'changeable' => [] ];

                foreach ( $allgroups as $group ) {
                        $set = in_array( $group, $usergroups );
                        // Should the checkbox be disabled?
                        $disabled = !(
                                ( $set && $this->canRemove( $group ) ) ||
                                ( !$set && $this->canAdd( $group ) ) );
                        // Do we need to point out that this action is irreversible?
                        $irreversible = !$disabled && (
                                ( $set && !$this->canAdd( $group ) ) ||
                                ( !$set && !$this->canRemove( $group ) ) );

                        $checkbox = [
                                'set' => $set,
                                'disabled' => $disabled,
                                'irreversible' => $irreversible
                        ];

                        if ( $disabled ) {
                                $columns['unchangeable'][$group] = $checkbox;
                        } else {
                                $columns['changeable'][$group] = $checkbox;
                        }
                }

                // Build the HTML table
                $ret .= Xml::openElement( 'table', [ 'class' => 'mw-userrights-groups' ] ) .
                        "<tr>\n";
                foreach ( $columns as $name => $column ) {
                        if ( $column === [] ) {
                                continue;
                        }
                        // Messages: userrights-changeable-col, userrights-unchangeable-col
                        $ret .= Xml::element(
                                'th',
                                null,
                                $this->msg( 'userrights-' . $name . '-col', count( $column ) )->text()
                        );
                }

                $ret .= "</tr>\n<tr>\n";
                foreach ( $columns as $column ) {
                        if ( $column === [] ) {
                                continue;
                        }
                        $ret .= "\t<td style='vertical-align:top;'>\n";
                        foreach ( $column as $group => $checkbox ) {
                                $attr = $checkbox['disabled'] ? [ 'disabled' => 'disabled' ] : [];

                                $member = User::getGroupMember( $group, $user->getName() );
                                if ( $checkbox['irreversible'] ) {
                                        $text = $this->msg( 'userrights-irreversible-marker', $member )->text();
                                } else {
                                        $text = $member;
                                }
                                $checkboxHtml = Xml::checkLabel( $text, "wpGroup-" . $group,
                                        "wpGroup-" . $group, $checkbox['set'], $attr );
                                $ret .= "\t\t" . ( $checkbox['disabled']
                                        ? Xml::tags( 'span', [ 'class' => 'mw-userrights-disabled' ], $checkboxHtml )
                                        : $checkboxHtml
                                ) . "<br />\n";
                        }
                        $ret .= "\t</td>\n";
                }
                $ret .= Xml::closeElement( 'tr' ) . Xml::closeElement( 'table' );

                return [ $ret, (bool)$columns['changeable'] ];
        }

        /**
         * @param string $group The name of the group to check
         * @return bool Can we remove the group?
         */
        private function canRemove( $group ) {
                $groups = $this->changeableGroups();

                return in_array(
                        $group,
                        $groups['remove'] ) || ( $this->isself && in_array( $group, $groups['remove-self'] )
                );
        }

        /**
         * @param string $group The name of the group to check
         * @return bool Can we add the group?
         */
        private function canAdd( $group ) {
                $groups = $this->changeableGroups();

                return in_array(
                        $group,
                        $groups['add'] ) || ( $this->isself && in_array( $group, $groups['add-self'] )
                );
        }

        /**
         * Returns $this->getUser()->changeableGroups()
         *
         * @return array Array(
         *   'add' => array( addablegroups ),
         *   'remove' => array( removablegroups ),
         *   'add-self' => array( addablegroups to self ),
         *   'remove-self' => array( removable groups from self )
         *  )
         */
        function changeableGroups() {
                return $this->getUser()->changeableGroups();
        }

        /**
         * Show a rights log fragment for the specified user
         *
         * @param User $user User to show log for
         * @param OutputPage $output OutputPage to use
         */
        protected function showLogFragment( $user, $output ) {
                $rightsLogPage = new LogPage( 'rights' );
                $output->addHTML( Xml::element( 'h2', null, $rightsLogPage->getName()->text() ) );
                LogEventsList::showLogExtract( $output, 'rights', $user->getUserPage() );
        }

        /**
         * Return an array of subpages beginning with $search that this special page will accept.
         *
         * @param string $search Prefix to search for
         * @param int $limit Maximum number of results to return (usually 10)
         * @param int $offset Number of results to skip (usually 0)
         * @return string[] Matching subpages
         */
        public function prefixSearchSubpages( $search, $limit, $offset ) {
                $user = User::newFromName( $search );
                if ( !$user ) {
                        // No prefix suggestion for invalid user
                        return [];
                }
                // Autocomplete subpage as user list - public to allow caching
                return UserNamePrefixSearch::search( 'public', $search, $limit, $offset );
        }

        protected function getGroupName() {
                return 'users';
        }
}