1<?php
2/**
3 * Shortcuts to construct a special page alias.
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18 * http://www.gnu.org/copyleft/gpl.html
19 *
20 * @file
21 * @ingroup SpecialPage
22 */
23
24/**
25 * Shortcut to construct a special page alias.
26 *
27 * @stable to extend
28 *
29 * @ingroup SpecialPage
30 */
31abstract class RedirectSpecialPage extends UnlistedSpecialPage {
32	/** @var array Query parameters that can be passed through redirects */
33	protected $mAllowedRedirectParams = [];
34
35	/** @var array Query parameters added by redirects */
36	protected $mAddedRedirectParams = [];
37
38	/**
39	 * @stable to override
40	 * @param string|null $subpage
41	 */
42	public function execute( $subpage ) {
43		$redirect = $this->getRedirect( $subpage );
44		$query = $this->getRedirectQuery( $subpage );
45
46		if ( $redirect instanceof Title ) {
47			// Redirect to a page title with possible query parameters
48			$url = $redirect->getFullUrlForRedirect( $query );
49			$this->getOutput()->redirect( $url );
50		} elseif ( $redirect === true ) {
51			// Redirect to index.php with query parameters
52			$url = wfAppendQuery( wfScript( 'index' ), $query );
53			$this->getOutput()->redirect( $url );
54		} else {
55			$this->showNoRedirectPage();
56		}
57	}
58
59	/**
60	 * If the special page is a redirect, then get the Title object it redirects to.
61	 * False otherwise.
62	 *
63	 * @param string|null $subpage
64	 * @return Title|bool
65	 */
66	abstract public function getRedirect( $subpage );
67
68	/**
69	 * Return part of the request string for a special redirect page
70	 * This allows passing, e.g. action=history to Special:Mypage, etc.
71	 *
72	 * @stable to override
73	 * @param string|null $subpage
74	 * @return array|bool
75	 */
76	public function getRedirectQuery( $subpage ) {
77		$params = [];
78		$request = $this->getRequest();
79
80		foreach ( array_merge( $this->mAllowedRedirectParams,
81				[ 'uselang', 'useskin', 'debug', 'safemode' ] // parameters which can be passed to all pages
82			) as $arg ) {
83			if ( $request->getVal( $arg, null ) !== null ) {
84				$params[$arg] = $request->getVal( $arg );
85			} elseif ( $request->getArray( $arg, null ) !== null ) {
86				$params[$arg] = $request->getArray( $arg );
87			}
88		}
89
90		foreach ( $this->mAddedRedirectParams as $arg => $val ) {
91			$params[$arg] = $val;
92		}
93
94		return count( $params )
95			? $params
96			: false;
97	}
98
99	/**
100	 * Indicate if the target of this redirect can be used to identify
101	 * a particular user of this wiki (e.g., if the redirect is to the
102	 * user page of a User). See T109724.
103	 *
104	 * @stable to override
105	 * @since 1.27
106	 * @return bool
107	 */
108	public function personallyIdentifiableTarget() {
109		return false;
110	}
111
112	/**
113	 * @stable to override
114	 */
115	protected function showNoRedirectPage() {
116		$class = static::class;
117		throw new MWException( "RedirectSpecialPage $class doesn't redirect!" );
118	}
119}
120