Merge "objectcache: Add some newlines to WANObjectCache docs"

[mediawiki.git] / includes / Linker.php

<?php
/**
 * Methods to make links and related items.
 *
 * 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
 */

/**
 * Some internal bits split of from Skin.php. These functions are used
 * for primarily page content: links, embedded images, table of contents. Links
 * are also used in the skin.
 *
 * @todo turn this into a legacy interface for HtmlPageLinkRenderer and similar services.
 *
 * @ingroup Skins
 */
class Linker {
        /**
         * Flags for userToolLinks()
         */
        const TOOL_LINKS_NOBLOCK = 1;
        const TOOL_LINKS_EMAIL = 2;

        /**
         * Get the appropriate HTML attributes to add to the "a" element of an interwiki link.
         *
         * @deprecated since 1.25
         *
         * @param string $title The title text for the link, URL-encoded (???) but
         *   not HTML-escaped
         * @param string $unused Unused
         * @param string $class The contents of the class attribute; if an empty
         *   string is passed, which is the default value, defaults to 'external'.
         * @return string
         */
        static function getInterwikiLinkAttributes( $title, $unused = null, $class = 'external' ) {
                global $wgContLang;

                wfDeprecated( __METHOD__, '1.25' );

                # @todo FIXME: We have a whole bunch of handling here that doesn't happen in
                # getExternalLinkAttributes, why?
                $title = urldecode( $title );
                $title = $wgContLang->checkTitleEncoding( $title );
                $title = preg_replace( '/[\\x00-\\x1f]/', ' ', $title );

                return self::getLinkAttributesInternal( $title, $class );
        }

        /**
         * Get the appropriate HTML attributes to add to the "a" element of an internal link.
         *
         * @deprecated since 1.25
         *
         * @param string $title The title text for the link, URL-encoded (???) but
         *   not HTML-escaped
         * @param string $unused Unused
         * @param string $class The contents of the class attribute, default none
         * @return string
         */
        static function getInternalLinkAttributes( $title, $unused = null, $class = '' ) {
                wfDeprecated( __METHOD__, '1.25' );

                $title = urldecode( $title );
                $title = strtr( $title, '_', ' ' );
                return self::getLinkAttributesInternal( $title, $class );
        }

        /**
         * Get the appropriate HTML attributes to add to the "a" element of an internal
         * link, given the Title object for the page we want to link to.
         *
         * @deprecated since 1.25
         *
         * @param Title $nt
         * @param string $unused Unused
         * @param string $class The contents of the class attribute, default none
         * @param string|bool $title Optional (unescaped) string to use in the title
         *   attribute; if false, default to the name of the page we're linking to
         * @return string
         */
        static function getInternalLinkAttributesObj( $nt, $unused = null, $class = '', $title = false ) {
                wfDeprecated( __METHOD__, '1.25' );

                if ( $title === false ) {
                        $title = $nt->getPrefixedText();
                }
                return self::getLinkAttributesInternal( $title, $class );
        }

        /**
         * Common code for getLinkAttributesX functions
         *
         * @deprecated since 1.25
         *
         * @param string $title
         * @param string $class
         *
         * @return string
         */
        private static function getLinkAttributesInternal( $title, $class ) {
                wfDeprecated( __METHOD__, '1.25' );

                $title = htmlspecialchars( $title );
                $class = htmlspecialchars( $class );
                $r = '';
                if ( $class != '' ) {
                        $r .= " class=\"$class\"";
                }
                if ( $title != '' ) {
                        $r .= " title=\"$title\"";
                }
                return $r;
        }

        /**
         * Return the CSS colour of a known link
         *
         * @param Title $t
         * @param int $threshold User defined threshold
         * @return string CSS class
         */
        public static function getLinkColour( $t, $threshold ) {
                $colour = '';
                if ( $t->isRedirect() ) {
                        # Page is a redirect
                        $colour = 'mw-redirect';
                } elseif ( $threshold > 0 && $t->isContentPage() &&
                        $t->exists() && $t->getLength() < $threshold
                ) {
                        # Page is a stub
                        $colour = 'stub';
                }
                return $colour;
        }

        /**
         * This function returns an HTML link to the given target.  It serves a few
         * purposes:
         *   1) If $target is a Title, the correct URL to link to will be figured
         *      out automatically.
         *   2) It automatically adds the usual classes for various types of link
         *      targets: "new" for red links, "stub" for short articles, etc.
         *   3) It escapes all attribute values safely so there's no risk of XSS.
         *   4) It provides a default tooltip if the target is a Title (the page
         *      name of the target).
         * link() replaces the old functions in the makeLink() family.
         *
         * @since 1.18 Method exists since 1.16 as non-static, made static in 1.18.
         *
         * @param Title $target Can currently only be a Title, but this may
         *   change to support Images, literal URLs, etc.
         * @param string $html The HTML contents of the <a> element, i.e.,
         *   the link text.  This is raw HTML and will not be escaped.  If null,
         *   defaults to the prefixed text of the Title; or if the Title is just a
         *   fragment, the contents of the fragment.
         * @param array $customAttribs A key => value array of extra HTML attributes,
         *   such as title and class.  (href is ignored.)  Classes will be
         *   merged with the default classes, while other attributes will replace
         *   default attributes.  All passed attribute values will be HTML-escaped.
         *   A false attribute value means to suppress that attribute.
         * @param array $query The query string to append to the URL
         *   you're linking to, in key => value array form.  Query keys and values
         *   will be URL-encoded.
         * @param string|array $options String or array of strings:
         *     'known': Page is known to exist, so don't check if it does.
         *     'broken': Page is known not to exist, so don't check if it does.
         *     'noclasses': Don't add any classes automatically (includes "new",
         *       "stub", "mw-redirect", "extiw").  Only use the class attribute
         *       provided, if any, so you get a simple blue link with no funny i-
         *       cons.
         *     'forcearticlepath': Use the article path always, even with a querystring.
         *       Has compatibility issues on some setups, so avoid wherever possible.
         *     'http': Force a full URL with http:// as the scheme.
         *     'https': Force a full URL with https:// as the scheme.
         * @return string HTML <a> attribute
         */
        public static function link(
                $target, $html = null, $customAttribs = array(), $query = array(), $options = array()
        ) {
                if ( !$target instanceof Title ) {
                        wfWarn( __METHOD__ . ': Requires $target to be a Title object.', 2 );
                        return "<!-- ERROR -->$html";
                }

                if ( is_string( $query ) ) {
                        // some functions withing core using this still hand over query strings
                        wfDeprecated( __METHOD__ . ' with parameter $query as string (should be array)', '1.20' );
                        $query = wfCgiToArray( $query );
                }
                $options = (array)$options;

                $dummy = new DummyLinker; // dummy linker instance for bc on the hooks

                $ret = null;
                if ( !Hooks::run( 'LinkBegin',
                        array( $dummy, $target, &$html, &$customAttribs, &$query, &$options, &$ret ) )
                ) {
                        return $ret;
                }

                # Normalize the Title if it's a special page
                $target = self::normaliseSpecialPage( $target );

                # If we don't know whether the page exists, let's find out.
                if ( !in_array( 'known', $options ) && !in_array( 'broken', $options ) ) {
                        if ( $target->isKnown() ) {
                                $options[] = 'known';
                        } else {
                                $options[] = 'broken';
                        }
                }

                $oldquery = array();
                if ( in_array( "forcearticlepath", $options ) && $query ) {
                        $oldquery = $query;
                        $query = array();
                }

                # Note: we want the href attribute first, for prettiness.
                $attribs = array( 'href' => self::linkUrl( $target, $query, $options ) );
                if ( in_array( 'forcearticlepath', $options ) && $oldquery ) {
                        $attribs['href'] = wfAppendQuery( $attribs['href'], $oldquery );
                }

                $attribs = array_merge(
                        $attribs,
                        self::linkAttribs( $target, $customAttribs, $options )
                );
                if ( is_null( $html ) ) {
                        $html = self::linkText( $target );
                }

                $ret = null;
                if ( Hooks::run( 'LinkEnd', array( $dummy, $target, $options, &$html, &$attribs, &$ret ) ) ) {
                        $ret = Html::rawElement( 'a', $attribs, $html );
                }

                return $ret;
        }

        /**
         * Identical to link(), except $options defaults to 'known'.
         * @see Linker::link
         * @return string
         */
        public static function linkKnown(
                $target, $html = null, $customAttribs = array(),
                $query = array(), $options = array( 'known', 'noclasses' )
        ) {
                return self::link( $target, $html, $customAttribs, $query, $options );
        }

        /**
         * Returns the Url used to link to a Title
         *
         * @param Title $target
         * @param array $query Query parameters
         * @param array $options
         * @return string
         */
        private static function linkUrl( $target, $query, $options ) {
                # We don't want to include fragments for broken links, because they
                # generally make no sense.
                if ( in_array( 'broken', $options ) && $target->hasFragment() ) {
                        $target = clone $target;
                        $target->setFragment( '' );
                }

                # If it's a broken link, add the appropriate query pieces, unless
                # there's already an action specified, or unless 'edit' makes no sense
                # (i.e., for a nonexistent special page).
                if ( in_array( 'broken', $options ) && empty( $query['action'] )
                        && !$target->isSpecialPage() ) {
                        $query['action'] = 'edit';
                        $query['redlink'] = '1';
                }

                if ( in_array( 'http', $options ) ) {
                        $proto = PROTO_HTTP;
                } elseif ( in_array( 'https', $options ) ) {
                        $proto = PROTO_HTTPS;
                } else {
                        $proto = PROTO_RELATIVE;
                }

                $ret = $target->getLinkURL( $query, false, $proto );
                return $ret;
        }

        /**
         * Returns the array of attributes used when linking to the Title $target
         *
         * @param Title $target
         * @param array $attribs
         * @param array $options
         *
         * @return array
         */
        private static function linkAttribs( $target, $attribs, $options ) {
                global $wgUser;
                $defaults = array();

                if ( !in_array( 'noclasses', $options ) ) {
                        # Now build the classes.
                        $classes = array();

                        if ( in_array( 'broken', $options ) ) {
                                $classes[] = 'new';
                        }

                        if ( $target->isExternal() ) {
                                $classes[] = 'extiw';
                        }

                        if ( !in_array( 'broken', $options ) ) { # Avoid useless calls to LinkCache (see r50387)
                                $colour = self::getLinkColour( $target, $wgUser->getStubThreshold() );
                                if ( $colour !== '' ) {
                                        $classes[] = $colour; # mw-redirect or stub
                                }
                        }
                        if ( $classes != array() ) {
                                $defaults['class'] = implode( ' ', $classes );
                        }
                }

                # Get a default title attribute.
                if ( $target->getPrefixedText() == '' ) {
                        # A link like [[#Foo]].  This used to mean an empty title
                        # attribute, but that's silly.  Just don't output a title.
                } elseif ( in_array( 'known', $options ) ) {
                        $defaults['title'] = $target->getPrefixedText();
                } else {
                        $defaults['title'] = wfMessage( 'red-link-title', $target->getPrefixedText() )->text();
                }

                # Finally, merge the custom attribs with the default ones, and iterate
                # over that, deleting all "false" attributes.
                $ret = array();
                $merged = Sanitizer::mergeAttributes( $defaults, $attribs );
                foreach ( $merged as $key => $val ) {
                        # A false value suppresses the attribute, and we don't want the
                        # href attribute to be overridden.
                        if ( $key != 'href' && $val !== false ) {
                                $ret[$key] = $val;
                        }
                }
                return $ret;
        }

        /**
         * Default text of the links to the Title $target
         *
         * @param Title $target
         *
         * @return string
         */
        private static function linkText( $target ) {
                if ( !$target instanceof Title ) {
                        wfWarn( __METHOD__ . ': Requires $target to be a Title object.' );
                        return '';
                }
                // If the target is just a fragment, with no title, we return the fragment
                // text.  Otherwise, we return the title text itself.
                if ( $target->getPrefixedText() === '' && $target->hasFragment() ) {
                        return htmlspecialchars( $target->getFragment() );
                }

                return htmlspecialchars( $target->getPrefixedText() );
        }

        /**
         * Make appropriate markup for a link to the current article. This is
         * currently rendered as the bold link text. The calling sequence is the
         * same as the other make*LinkObj static functions, despite $query not
         * being used.
         *
         * @param Title $nt
         * @param string $html [optional]
         * @param string $query [optional]
         * @param string $trail [optional]
         * @param string $prefix [optional]
         *
         * @return string
         */
        public static function makeSelfLinkObj( $nt, $html = '', $query = '', $trail = '', $prefix = '' ) {
                $ret = "<strong class=\"selflink\">{$prefix}{$html}</strong>{$trail}";
                if ( !Hooks::run( 'SelfLinkBegin', array( $nt, &$html, &$trail, &$prefix, &$ret ) ) ) {
                        return $ret;
                }

                if ( $html == '' ) {
                        $html = htmlspecialchars( $nt->getPrefixedText() );
                }
                list( $inside, $trail ) = self::splitTrail( $trail );
                return "<strong class=\"selflink\">{$prefix}{$html}{$inside}</strong>{$trail}";
        }

        /**
         * Get a message saying that an invalid title was encountered.
         * This should be called after a method like Title::makeTitleSafe() returned
         * a value indicating that the title object is invalid.
         *
         * @param IContextSource $context Context to use to get the messages
         * @param int $namespace Namespace number
         * @param string $title Text of the title, without the namespace part
         * @return string
         */
        public static function getInvalidTitleDescription( IContextSource $context, $namespace, $title ) {
                global $wgContLang;

                // First we check whether the namespace exists or not.
                if ( MWNamespace::exists( $namespace ) ) {
                        if ( $namespace == NS_MAIN ) {
                                $name = $context->msg( 'blanknamespace' )->text();
                        } else {
                                $name = $wgContLang->getFormattedNsText( $namespace );
                        }
                        return $context->msg( 'invalidtitle-knownnamespace', $namespace, $name, $title )->text();
                } else {
                        return $context->msg( 'invalidtitle-unknownnamespace', $namespace, $title )->text();
                }
        }

        /**
         * @param Title $title
         * @return Title
         */
        static function normaliseSpecialPage( Title $title ) {
                if ( $title->isSpecialPage() ) {
                        list( $name, $subpage ) = SpecialPageFactory::resolveAlias( $title->getDBkey() );
                        if ( !$name ) {
                                return $title;
                        }
                        $ret = SpecialPage::getTitleFor( $name, $subpage, $title->getFragment() );
                        return $ret;
                } else {
                        return $title;
                }
        }

        /**
         * Returns the filename part of an url.
         * Used as alternative text for external images.
         *
         * @param string $url
         *
         * @return string
         */
        private static function fnamePart( $url ) {
                $basename = strrchr( $url, '/' );
                if ( false === $basename ) {
                        $basename = $url;
                } else {
                        $basename = substr( $basename, 1 );
                }
                return $basename;
        }

        /**
         * Return the code for images which were added via external links,
         * via Parser::maybeMakeExternalImage().
         *
         * @param string $url
         * @param string $alt
         *
         * @return string
         */
        public static function makeExternalImage( $url, $alt = '' ) {
                if ( $alt == '' ) {
                        $alt = self::fnamePart( $url );
                }
                $img = '';
                $success = Hooks::run( 'LinkerMakeExternalImage', array( &$url, &$alt, &$img ) );
                if ( !$success ) {
                        wfDebug( "Hook LinkerMakeExternalImage changed the output of external image "
                                . "with url {$url} and alt text {$alt} to {$img}\n", true );
                        return $img;
                }
                return Html::element( 'img',
                        array(
                                'src' => $url,
                                'alt' => $alt ) );
        }

        /**
         * Given parameters derived from [[Image:Foo|options...]], generate the
         * HTML that that syntax inserts in the page.
         *
         * @param Parser $parser
         * @param Title $title Title object of the file (not the currently viewed page)
         * @param File $file File object, or false if it doesn't exist
         * @param array $frameParams Associative array of parameters external to the media handler.
         *     Boolean parameters are indicated by presence or absence, the value is arbitrary and
         *     will often be false.
         *          thumbnail       If present, downscale and frame
         *          manualthumb     Image name to use as a thumbnail, instead of automatic scaling
         *          framed          Shows image in original size in a frame
         *          frameless       Downscale but don't frame
         *          upright         If present, tweak default sizes for portrait orientation
         *          upright_factor  Fudge factor for "upright" tweak (default 0.75)
         *          border          If present, show a border around the image
         *          align           Horizontal alignment (left, right, center, none)
         *          valign          Vertical alignment (baseline, sub, super, top, text-top, middle,
         *                          bottom, text-bottom)
         *          alt             Alternate text for image (i.e. alt attribute). Plain text.
         *          class           HTML for image classes. Plain text.
         *          caption         HTML for image caption.
         *          link-url        URL to link to
         *          link-title      Title object to link to
         *          link-target     Value for the target attribute, only with link-url
         *          no-link         Boolean, suppress description link
         *
         * @param array $handlerParams Associative array of media handler parameters, to be passed
         *       to transform(). Typical keys are "width" and "page".
         * @param string|bool $time Timestamp of the file, set as false for current
         * @param string $query Query params for desc url
         * @param int|null $widthOption Used by the parser to remember the user preference thumbnailsize
         * @since 1.20
         * @return string HTML for an image, with links, wrappers, etc.
         */
        public static function makeImageLink( Parser $parser, Title $title,
                $file, $frameParams = array(), $handlerParams = array(), $time = false,
                $query = "", $widthOption = null
        ) {
                $res = null;
                $dummy = new DummyLinker;
                if ( !Hooks::run( 'ImageBeforeProduceHTML', array( &$dummy, &$title,
                        &$file, &$frameParams, &$handlerParams, &$time, &$res ) ) ) {
                        return $res;
                }

                if ( $file && !$file->allowInlineDisplay() ) {
                        wfDebug( __METHOD__ . ': ' . $title->getPrefixedDBkey() . " does not allow inline display\n" );
                        return self::link( $title );
                }

                // Shortcuts
                $fp =& $frameParams;
                $hp =& $handlerParams;

                // Clean up parameters
                $page = isset( $hp['page'] ) ? $hp['page'] : false;
                if ( !isset( $fp['align'] ) ) {
                        $fp['align'] = '';
                }
                if ( !isset( $fp['alt'] ) ) {
                        $fp['alt'] = '';
                }
                if ( !isset( $fp['title'] ) ) {
                        $fp['title'] = '';
                }
                if ( !isset( $fp['class'] ) ) {
                        $fp['class'] = '';
                }

                $prefix = $postfix = '';

                if ( 'center' == $fp['align'] ) {
                        $prefix = '<div class="center">';
                        $postfix = '</div>';
                        $fp['align'] = 'none';
                }
                if ( $file && !isset( $hp['width'] ) ) {
                        if ( isset( $hp['height'] ) && $file->isVectorized() ) {
                                // If its a vector image, and user only specifies height
                                // we don't want it to be limited by its "normal" width.
                                global $wgSVGMaxSize;
                                $hp['width'] = $wgSVGMaxSize;
                        } else {
                                $hp['width'] = $file->getWidth( $page );
                        }

                        if ( isset( $fp['thumbnail'] )
                                || isset( $fp['manualthumb'] )
                                || isset( $fp['framed'] )
                                || isset( $fp['frameless'] )
                                || !$hp['width']
                        ) {
                                global $wgThumbLimits, $wgThumbUpright;

                                if ( $widthOption === null || !isset( $wgThumbLimits[$widthOption] ) ) {
                                        $widthOption = User::getDefaultOption( 'thumbsize' );
                                }

                                // Reduce width for upright images when parameter 'upright' is used
                                if ( isset( $fp['upright'] ) && $fp['upright'] == 0 ) {
                                        $fp['upright'] = $wgThumbUpright;
                                }

                                // For caching health: If width scaled down due to upright
                                // parameter, round to full __0 pixel to avoid the creation of a
                                // lot of odd thumbs.
                                $prefWidth = isset( $fp['upright'] ) ?
                                        round( $wgThumbLimits[$widthOption] * $fp['upright'], -1 ) :
                                        $wgThumbLimits[$widthOption];

                                // Use width which is smaller: real image width or user preference width
                                // Unless image is scalable vector.
                                if ( !isset( $hp['height'] ) && ( $hp['width'] <= 0 ||
                                                $prefWidth < $hp['width'] || $file->isVectorized() ) ) {
                                        $hp['width'] = $prefWidth;
                                }
                        }
                }

                if ( isset( $fp['thumbnail'] ) || isset( $fp['manualthumb'] ) || isset( $fp['framed'] ) ) {
                        # Create a thumbnail. Alignment depends on the writing direction of
                        # the page content language (right-aligned for LTR languages,
                        # left-aligned for RTL languages)
                        #
                        # If a thumbnail width has not been provided, it is set
                        # to the default user option as specified in Language*.php
                        if ( $fp['align'] == '' ) {
                                $fp['align'] = $parser->getTargetLanguage()->alignEnd();
                        }
                        return $prefix . self::makeThumbLink2( $title, $file, $fp, $hp, $time, $query ) . $postfix;
                }

                if ( $file && isset( $fp['frameless'] ) ) {
                        $srcWidth = $file->getWidth( $page );
                        # For "frameless" option: do not present an image bigger than the
                        # source (for bitmap-style images). This is the same behavior as the
                        # "thumb" option does it already.
                        if ( $srcWidth && !$file->mustRender() && $hp['width'] > $srcWidth ) {
                                $hp['width'] = $srcWidth;
                        }
                }

                if ( $file && isset( $hp['width'] ) ) {
                        # Create a resized image, without the additional thumbnail features
                        $thumb = $file->transform( $hp );
                } else {
                        $thumb = false;
                }

                if ( !$thumb ) {
                        $s = self::makeBrokenImageLinkObj( $title, $fp['title'], '', '', '', $time == true );
                } else {
                        self::processResponsiveImages( $file, $thumb, $hp );
                        $params = array(
                                'alt' => $fp['alt'],
                                'title' => $fp['title'],
                                'valign' => isset( $fp['valign'] ) ? $fp['valign'] : false,
                                'img-class' => $fp['class'] );
                        if ( isset( $fp['border'] ) ) {
                                $params['img-class'] .= ( $params['img-class'] !== '' ? ' ' : '' ) . 'thumbborder';
                        }
                        $params = self::getImageLinkMTOParams( $fp, $query, $parser ) + $params;

                        $s = $thumb->toHtml( $params );
                }
                if ( $fp['align'] != '' ) {
                        $s = "<div class=\"float{$fp['align']}\">{$s}</div>";
                }
                return str_replace( "\n", ' ', $prefix . $s . $postfix );
        }

        /**
         * See makeImageLink()
         * When this function is removed, remove if( $parser instanceof Parser ) check there too
         * @deprecated since 1.20
         */
        public static function makeImageLink2( Title $title, $file, $frameParams = array(),
                $handlerParams = array(), $time = false, $query = "", $widthOption = null ) {
                return self::makeImageLink( null, $title, $file, $frameParams,
                        $handlerParams, $time, $query, $widthOption );
        }

        /**
         * Get the link parameters for MediaTransformOutput::toHtml() from given
         * frame parameters supplied by the Parser.
         * @param array $frameParams The frame parameters
         * @param string $query An optional query string to add to description page links
         * @param Parser|null $parser
         * @return array
         */
        private static function getImageLinkMTOParams( $frameParams, $query = '', $parser = null ) {
                $mtoParams = array();
                if ( isset( $frameParams['link-url'] ) && $frameParams['link-url'] !== '' ) {
                        $mtoParams['custom-url-link'] = $frameParams['link-url'];
                        if ( isset( $frameParams['link-target'] ) ) {
                                $mtoParams['custom-target-link'] = $frameParams['link-target'];
                        }
                        if ( $parser ) {
                                $extLinkAttrs = $parser->getExternalLinkAttribs( $frameParams['link-url'] );
                                foreach ( $extLinkAttrs as $name => $val ) {
                                        // Currently could include 'rel' and 'target'
                                        $mtoParams['parser-extlink-' . $name] = $val;
                                }
                        }
                } elseif ( isset( $frameParams['link-title'] ) && $frameParams['link-title'] !== '' ) {
                        $mtoParams['custom-title-link'] = self::normaliseSpecialPage( $frameParams['link-title'] );
                } elseif ( !empty( $frameParams['no-link'] ) ) {
                        // No link
                } else {
                        $mtoParams['desc-link'] = true;
                        $mtoParams['desc-query'] = $query;
                }
                return $mtoParams;
        }

        /**
         * Make HTML for a thumbnail including image, border and caption
         * @param Title $title
         * @param File|bool $file File object or false if it doesn't exist
         * @param string $label
         * @param string $alt
         * @param string $align
         * @param array $params
         * @param bool $framed
         * @param string $manualthumb
         * @return string
         */
        public static function makeThumbLinkObj( Title $title, $file, $label = '', $alt,
                $align = 'right', $params = array(), $framed = false, $manualthumb = ""
        ) {
                $frameParams = array(
                        'alt' => $alt,
                        'caption' => $label,
                        'align' => $align
                );
                if ( $framed ) {
                        $frameParams['framed'] = true;
                }
                if ( $manualthumb ) {
                        $frameParams['manualthumb'] = $manualthumb;
                }
                return self::makeThumbLink2( $title, $file, $frameParams, $params );
        }

        /**
         * @param Title $title
         * @param File $file
         * @param array $frameParams
         * @param array $handlerParams
         * @param bool $time
         * @param string $query
         * @return string
         */
        public static function makeThumbLink2( Title $title, $file, $frameParams = array(),
                $handlerParams = array(), $time = false, $query = ""
        ) {
                $exists = $file && $file->exists();

                # Shortcuts
                $fp =& $frameParams;
                $hp =& $handlerParams;

                $page = isset( $hp['page'] ) ? $hp['page'] : false;
                if ( !isset( $fp['align'] ) ) {
                        $fp['align'] = 'right';
                }
                if ( !isset( $fp['alt'] ) ) {
                        $fp['alt'] = '';
                }
                if ( !isset( $fp['title'] ) ) {
                        $fp['title'] = '';
                }
                if ( !isset( $fp['caption'] ) ) {
                        $fp['caption'] = '';
                }

                if ( empty( $hp['width'] ) ) {
                        // Reduce width for upright images when parameter 'upright' is used
                        $hp['width'] = isset( $fp['upright'] ) ? 130 : 180;
                }
                $thumb = false;
                $noscale = false;
                $manualthumb = false;

                if ( !$exists ) {
                        $outerWidth = $hp['width'] + 2;
                } else {
                        if ( isset( $fp['manualthumb'] ) ) {
                                # Use manually specified thumbnail
                                $manual_title = Title::makeTitleSafe( NS_FILE, $fp['manualthumb'] );
                                if ( $manual_title ) {
                                        $manual_img = wfFindFile( $manual_title );
                                        if ( $manual_img ) {
                                                $thumb = $manual_img->getUnscaledThumb( $hp );
                                                $manualthumb = true;
                                        } else {
                                                $exists = false;
                                        }
                                }
                        } elseif ( isset( $fp['framed'] ) ) {
                                // Use image dimensions, don't scale
                                $thumb = $file->getUnscaledThumb( $hp );
                                $noscale = true;
                        } else {
                                # Do not present an image bigger than the source, for bitmap-style images
                                # This is a hack to maintain compatibility with arbitrary pre-1.10 behavior
                                $srcWidth = $file->getWidth( $page );
                                if ( $srcWidth && !$file->mustRender() && $hp['width'] > $srcWidth ) {
                                        $hp['width'] = $srcWidth;
                                }
                                $thumb = $file->transform( $hp );
                        }

                        if ( $thumb ) {
                                $outerWidth = $thumb->getWidth() + 2;
                        } else {
                                $outerWidth = $hp['width'] + 2;
                        }
                }

                # ThumbnailImage::toHtml() already adds page= onto the end of DjVu URLs
                # So we don't need to pass it here in $query. However, the URL for the
                # zoom icon still needs it, so we make a unique query for it. See bug 14771
                $url = $title->getLocalURL( $query );
                if ( $page ) {
                        $url = wfAppendQuery( $url, array( 'page' => $page ) );
                }
                if ( $manualthumb
                        && !isset( $fp['link-title'] )
                        && !isset( $fp['link-url'] )
                        && !isset( $fp['no-link'] ) ) {
                        $fp['link-url'] = $url;
                }

                $s = "<div class=\"thumb t{$fp['align']}\">"
                        . "<div class=\"thumbinner\" style=\"width:{$outerWidth}px;\">";

                if ( !$exists ) {
                        $s .= self::makeBrokenImageLinkObj( $title, $fp['title'], '', '', '', $time == true );
                        $zoomIcon = '';
                } elseif ( !$thumb ) {
                        $s .= wfMessage( 'thumbnail_error', '' )->escaped();
                        $zoomIcon = '';
                } else {
                        if ( !$noscale && !$manualthumb ) {
                                self::processResponsiveImages( $file, $thumb, $hp );
                        }
                        $params = array(
                                'alt' => $fp['alt'],
                                'title' => $fp['title'],
                                'img-class' => ( isset( $fp['class'] ) && $fp['class'] !== ''
                                        ? $fp['class'] . ' '
                                        : '' ) . 'thumbimage'
                        );
                        $params = self::getImageLinkMTOParams( $fp, $query ) + $params;
                        $s .= $thumb->toHtml( $params );
                        if ( isset( $fp['framed'] ) ) {
                                $zoomIcon = "";
                        } else {
                                $zoomIcon = Html::rawElement( 'div', array( 'class' => 'magnify' ),
                                        Html::rawElement( 'a', array(
                                                'href' => $url,
                                                'class' => 'internal',
                                                'title' => wfMessage( 'thumbnail-more' )->text() ),
                                                "" ) );
                        }
                }
                $s .= '  <div class="thumbcaption">' . $zoomIcon . $fp['caption'] . "</div></div></div>";
                return str_replace( "\n", ' ', $s );
        }

        /**
         * Process responsive images: add 1.5x and 2x subimages to the thumbnail, where
         * applicable.
         *
         * @param File $file
         * @param MediaTransformOutput $thumb
         * @param array $hp Image parameters
         */
        public static function processResponsiveImages( $file, $thumb, $hp ) {
                global $wgResponsiveImages;
                if ( $wgResponsiveImages && $thumb && !$thumb->isError() ) {
                        $hp15 = $hp;
                        $hp15['width'] = round( $hp['width'] * 1.5 );
                        $hp20 = $hp;
                        $hp20['width'] = $hp['width'] * 2;
                        if ( isset( $hp['height'] ) ) {
                                $hp15['height'] = round( $hp['height'] * 1.5 );
                                $hp20['height'] = $hp['height'] * 2;
                        }

                        $thumb15 = $file->transform( $hp15 );
                        $thumb20 = $file->transform( $hp20 );
                        if ( $thumb15 && !$thumb15->isError() && $thumb15->getUrl() !== $thumb->getUrl() ) {
                                $thumb->responsiveUrls['1.5'] = $thumb15->getUrl();
                        }
                        if ( $thumb20 && !$thumb20->isError() && $thumb20->getUrl() !== $thumb->getUrl() ) {
                                $thumb->responsiveUrls['2'] = $thumb20->getUrl();
                        }
                }
        }

        /**
         * Make a "broken" link to an image
         *
         * @param Title $title
         * @param string $label Link label (plain text)
         * @param string $query Query string
         * @param string $unused1 Unused parameter kept for b/c
         * @param string $unused2 Unused parameter kept for b/c
         * @param bool $time A file of a certain timestamp was requested
         * @return string
         */
        public static function makeBrokenImageLinkObj( $title, $label = '',
                $query = '', $unused1 = '', $unused2 = '', $time = false
        ) {
                if ( !$title instanceof Title ) {
                        wfWarn( __METHOD__ . ': Requires $title to be a Title object.' );
                        return "<!-- ERROR -->" . htmlspecialchars( $label );
                }

                global $wgEnableUploads, $wgUploadMissingFileUrl, $wgUploadNavigationUrl;
                if ( $label == '' ) {
                        $label = $title->getPrefixedText();
                }
                $encLabel = htmlspecialchars( $label );
                $currentExists = $time ? ( wfFindFile( $title ) != false ) : false;

                if ( ( $wgUploadMissingFileUrl || $wgUploadNavigationUrl || $wgEnableUploads )
                        && !$currentExists
                ) {
                        $redir = RepoGroup::singleton()->getLocalRepo()->checkRedirect( $title );

                        if ( $redir ) {
                                return self::linkKnown( $title, $encLabel, array(), wfCgiToArray( $query ) );
                        }

                        $href = self::getUploadUrl( $title, $query );

                        return '<a href="' . htmlspecialchars( $href ) . '" class="new" title="' .
                                htmlspecialchars( $title->getPrefixedText(), ENT_QUOTES ) . '">' .
                                $encLabel . '</a>';
                }

                return self::linkKnown( $title, $encLabel, array(), wfCgiToArray( $query ) );
        }

        /**
         * Get the URL to upload a certain file
         *
         * @param Title $destFile Title object of the file to upload
         * @param string $query Urlencoded query string to prepend
         * @return string Urlencoded URL
         */
        protected static function getUploadUrl( $destFile, $query = '' ) {
                global $wgUploadMissingFileUrl, $wgUploadNavigationUrl;
                $q = 'wpDestFile=' . $destFile->getPartialURL();
                if ( $query != '' ) {
                        $q .= '&' . $query;
                }

                if ( $wgUploadMissingFileUrl ) {
                        return wfAppendQuery( $wgUploadMissingFileUrl, $q );
                } elseif ( $wgUploadNavigationUrl ) {
                        return wfAppendQuery( $wgUploadNavigationUrl, $q );
                } else {
                        $upload = SpecialPage::getTitleFor( 'Upload' );
                        return $upload->getLocalURL( $q );
                }
        }

        /**
         * Create a direct link to a given uploaded file.
         *
         * @param Title $title
         * @param string $html Pre-sanitized HTML
         * @param string $time MW timestamp of file creation time
         * @return string HTML
         */
        public static function makeMediaLinkObj( $title, $html = '', $time = false ) {
                $img = wfFindFile( $title, array( 'time' => $time ) );
                return self::makeMediaLinkFile( $title, $img, $html );
        }

        /**
         * Create a direct link to a given uploaded file.
         * This will make a broken link if $file is false.
         *
         * @param Title $title
         * @param File|bool $file File object or false
         * @param string $html Pre-sanitized HTML
         * @return string HTML
         *
         * @todo Handle invalid or missing images better.
         */
        public static function makeMediaLinkFile( Title $title, $file, $html = '' ) {
                if ( $file && $file->exists() ) {
                        $url = $file->getURL();
                        $class = 'internal';
                } else {
                        $url = self::getUploadUrl( $title );
                        $class = 'new';
                }

                $alt = $title->getText();
                if ( $html == '' ) {
                        $html = $alt;
                }

                $ret = '';
                $attribs = array(
                        'href' => $url,
                        'class' => $class,
                        'title' => $alt
                );

                if ( !Hooks::run( 'LinkerMakeMediaLinkFile',
                        array( $title, $file, &$html, &$attribs, &$ret ) ) ) {
                        wfDebug( "Hook LinkerMakeMediaLinkFile changed the output of link "
                                . "with url {$url} and text {$html} to {$ret}\n", true );
                        return $ret;
                }

                return Html::rawElement( 'a', $attribs, $html );
        }

        /**
         * Make a link to a special page given its name and, optionally,
         * a message key from the link text.
         * Usage example: Linker::specialLink( 'Recentchanges' )
         *
         * @param string $name
         * @param string $key
         * @return string
         */
        public static function specialLink( $name, $key = '' ) {
                if ( $key == '' ) {
                        $key = strtolower( $name );
                }

                return self::linkKnown( SpecialPage::getTitleFor( $name ), wfMessage( $key )->text() );
        }

        /**
         * Make an external link
         * @param string $url URL to link to
         * @param string $text Text of link
         * @param bool $escape Do we escape the link text?
         * @param string $linktype Type of external link. Gets added to the classes
         * @param array $attribs Array of extra attributes to <a>
         * @param Title|null $title Title object used for title specific link attributes
         * @return string
         */
        public static function makeExternalLink( $url, $text, $escape = true,
                $linktype = '', $attribs = array(), $title = null
        ) {
                global $wgTitle;
                $class = "external";
                if ( $linktype ) {
                        $class .= " $linktype";
                }
                if ( isset( $attribs['class'] ) && $attribs['class'] ) {
                        $class .= " {$attribs['class']}";
                }
                $attribs['class'] = $class;

                if ( $escape ) {
                        $text = htmlspecialchars( $text );
                }

                if ( !$title ) {
                        $title = $wgTitle;
                }
                $attribs['rel'] = Parser::getExternalLinkRel( $url, $title );
                $link = '';
                $success = Hooks::run( 'LinkerMakeExternalLink',
                        array( &$url, &$text, &$link, &$attribs, $linktype ) );
                if ( !$success ) {
                        wfDebug( "Hook LinkerMakeExternalLink changed the output of link "
                                . "with url {$url} and text {$text} to {$link}\n", true );
                        return $link;
                }
                $attribs['href'] = $url;
                return Html::rawElement( 'a', $attribs, $text );
        }

        /**
         * Make user link (or user contributions for unregistered users)
         * @param int $userId User id in database.
         * @param string $userName User name in database.
         * @param string $altUserName Text to display instead of the user name (optional)
         * @return string HTML fragment
         * @since 1.19 Method exists for a long time. $altUserName was added in 1.19.
         */
        public static function userLink( $userId, $userName, $altUserName = false ) {
                $classes = 'mw-userlink';
                if ( $userId == 0 ) {
                        $page = SpecialPage::getTitleFor( 'Contributions', $userName );
                        if ( $altUserName === false ) {
                                $altUserName = IP::prettifyIP( $userName );
                        }
                        $classes .= ' mw-anonuserlink'; // Separate link class for anons (bug 43179)
                } else {
                        $page = Title::makeTitle( NS_USER, $userName );
                }

                return self::link(
                        $page,
                        htmlspecialchars( $altUserName !== false ? $altUserName : $userName ),
                        array( 'class' => $classes )
                );
        }

        /**
         * Generate standard user tool links (talk, contributions, block link, etc.)
         *
         * @param int $userId User identifier
         * @param string $userText User name or IP address
         * @param bool $redContribsWhenNoEdits Should the contributions link be
         *   red if the user has no edits?
         * @param int $flags Customisation flags (e.g. Linker::TOOL_LINKS_NOBLOCK
         *   and Linker::TOOL_LINKS_EMAIL).
         * @param int $edits User edit count (optional, for performance)
         * @return string HTML fragment
         */
        public static function userToolLinks(
                $userId, $userText, $redContribsWhenNoEdits = false, $flags = 0, $edits = null
        ) {
                global $wgUser, $wgDisableAnonTalk, $wgLang;
                $talkable = !( $wgDisableAnonTalk && 0 == $userId );
                $blockable = !( $flags & self::TOOL_LINKS_NOBLOCK );
                $addEmailLink = $flags & self::TOOL_LINKS_EMAIL && $userId;

                $items = array();
                if ( $talkable ) {
                        $items[] = self::userTalkLink( $userId, $userText );
                }
                if ( $userId ) {
                        // check if the user has an edit
                        $attribs = array();
                        if ( $redContribsWhenNoEdits ) {
                                if ( intval( $edits ) === 0 && $edits !== 0 ) {
                                        $user = User::newFromId( $userId );
                                        $edits = $user->getEditCount();
                                }
                                if ( $edits === 0 ) {
                                        $attribs['class'] = 'new';
                                }
                        }
                        $contribsPage = SpecialPage::getTitleFor( 'Contributions', $userText );

                        $items[] = self::link( $contribsPage, wfMessage( 'contribslink' )->escaped(), $attribs );
                }
                if ( $blockable && $wgUser->isAllowed( 'block' ) ) {
                        $items[] = self::blockLink( $userId, $userText );
                }

                if ( $addEmailLink && $wgUser->canSendEmail() ) {
                        $items[] = self::emailLink( $userId, $userText );
                }

                Hooks::run( 'UserToolLinksEdit', array( $userId, $userText, &$items ) );

                if ( $items ) {
                        return wfMessage( 'word-separator' )->escaped()
                                . '<span class="mw-usertoollinks">'
                                . wfMessage( 'parentheses' )->rawParams( $wgLang->pipeList( $items ) )->escaped()
                                . '</span>';
                } else {
                        return '';
                }
        }

        /**
         * Alias for userToolLinks( $userId, $userText, true );
         * @param int $userId User identifier
         * @param string $userText User name or IP address
         * @param int $edits User edit count (optional, for performance)
         * @return string
         */
        public static function userToolLinksRedContribs( $userId, $userText, $edits = null ) {
                return self::userToolLinks( $userId, $userText, true, 0, $edits );
        }

        /**
         * @param int $userId User id in database.
         * @param string $userText User name in database.
         * @return string HTML fragment with user talk link
         */
        public static function userTalkLink( $userId, $userText ) {
                $userTalkPage = Title::makeTitle( NS_USER_TALK, $userText );
                $userTalkLink = self::link( $userTalkPage, wfMessage( 'talkpagelinktext' )->escaped() );
                return $userTalkLink;
        }

        /**
         * @param int $userId Userid
         * @param string $userText User name in database.
         * @return string HTML fragment with block link
         */
        public static function blockLink( $userId, $userText ) {
                $blockPage = SpecialPage::getTitleFor( 'Block', $userText );
                $blockLink = self::link( $blockPage, wfMessage( 'blocklink' )->escaped() );
                return $blockLink;
        }

        /**
         * @param int $userId Userid
         * @param string $userText User name in database.
         * @return string HTML fragment with e-mail user link
         */
        public static function emailLink( $userId, $userText ) {
                $emailPage = SpecialPage::getTitleFor( 'Emailuser', $userText );
                $emailLink = self::link( $emailPage, wfMessage( 'emaillink' )->escaped() );
                return $emailLink;
        }

        /**
         * Generate a user link if the current user is allowed to view it
         * @param Revision $rev
         * @param bool $isPublic Show only if all users can see it
         * @return string HTML fragment
         */
        public static function revUserLink( $rev, $isPublic = false ) {
                if ( $rev->isDeleted( Revision::DELETED_USER ) && $isPublic ) {
                        $link = wfMessage( 'rev-deleted-user' )->escaped();
                } elseif ( $rev->userCan( Revision::DELETED_USER ) ) {
                        $link = self::userLink( $rev->getUser( Revision::FOR_THIS_USER ),
                                $rev->getUserText( Revision::FOR_THIS_USER ) );
                } else {
                        $link = wfMessage( 'rev-deleted-user' )->escaped();
                }
                if ( $rev->isDeleted( Revision::DELETED_USER ) ) {
                        return '<span class="history-deleted">' . $link . '</span>';
                }
                return $link;
        }

        /**
         * Generate a user tool link cluster if the current user is allowed to view it
         * @param Revision $rev
         * @param bool $isPublic Show only if all users can see it
         * @return string HTML
         */
        public static function revUserTools( $rev, $isPublic = false ) {
                if ( $rev->isDeleted( Revision::DELETED_USER ) && $isPublic ) {
                        $link = wfMessage( 'rev-deleted-user' )->escaped();
                } elseif ( $rev->userCan( Revision::DELETED_USER ) ) {
                        $userId = $rev->getUser( Revision::FOR_THIS_USER );
                        $userText = $rev->getUserText( Revision::FOR_THIS_USER );
                        $link = self::userLink( $userId, $userText )
                                . self::userToolLinks( $userId, $userText );
                } else {
                        $link = wfMessage( 'rev-deleted-user' )->escaped();
                }
                if ( $rev->isDeleted( Revision::DELETED_USER ) ) {
                        return ' <span class="history-deleted">' . $link . '</span>';
                }
                return $link;
        }

        /**
         * This function is called by all recent changes variants, by the page history,
         * and by the user contributions list. It is responsible for formatting edit
         * summaries. It escapes any HTML in the summary, but adds some CSS to format
         * auto-generated comments (from section editing) and formats [[wikilinks]].
         *
         * @author Erik Moeller <moeller@scireview.de>
         *
         * Note: there's not always a title to pass to this function.
         * Since you can't set a default parameter for a reference, I've turned it
         * temporarily to a value pass. Should be adjusted further. --brion
         *
         * @param string $comment
         * @param Title|null $title Title object (to generate link to the section in autocomment)
         *  or null
         * @param bool $local Whether section links should refer to local page
         * @param string|null $wikiId Id (as used by WikiMap) of the wiki to generate links to.
         *  For use with external changes.
         *
         * @return mixed|string
         */
        public static function formatComment(
                $comment, $title = null, $local = false, $wikiId = null
        ) {
                # Sanitize text a bit:
                $comment = str_replace( "\n", " ", $comment );
                # Allow HTML entities (for bug 13815)
                $comment = Sanitizer::escapeHtmlAllowEntities( $comment );

                # Render autocomments and make links:
                $comment = self::formatAutocomments( $comment, $title, $local, $wikiId );
                $comment = self::formatLinksInComment( $comment, $title, $local, $wikiId );

                return $comment;
        }

        /**
         * Converts autogenerated comments in edit summaries into section links.
         *
         * The pattern for autogen comments is / * foo * /, which makes for
         * some nasty regex.
         * We look for all comments, match any text before and after the comment,
         * add a separator where needed and format the comment itself with CSS
         * Called by Linker::formatComment.
         *
         * @param string $comment Comment text
         * @param Title|null $title An optional title object used to links to sections
         * @param bool $local Whether section links should refer to local page
         * @param string|null $wikiId Id of the wiki to link to (if not the local wiki),
         *  as used by WikiMap.
         *
         * @return string Formatted comment (wikitext)
         */
        private static function formatAutocomments(
                $comment, $title = null, $local = false, $wikiId = null
        ) {
                // @todo $append here is something of a hack to preserve the status
                // quo. Someone who knows more about bidi and such should decide
                // (1) what sane rendering even *is* for an LTR edit summary on an RTL
                // wiki, both when autocomments exist and when they don't, and
                // (2) what markup will make that actually happen.
                $append = '';
                $comment = preg_replace_callback(
                        // To detect the presence of content before or after the
                        // auto-comment, we use capturing groups inside optional zero-width
                        // assertions. But older versions of PCRE can't directly make
                        // zero-width assertions optional, so wrap them in a non-capturing
                        // group.
                        '!(?:(?<=(.)))?/\*\s*(.*?)\s*\*/(?:(?=(.)))?!',
                        function ( $match ) use ( $title, $local, $wikiId, &$append ) {
                                global $wgLang;

                                // Ensure all match positions are defined
                                $match += array( '', '', '', '' );

                                $pre = $match[1] !== '';
                                $auto = $match[2];
                                $post = $match[3] !== '';
                                $comment = null;

                                Hooks::run(
                                        'FormatAutocomments',
                                        array( &$comment, $pre, $auto, $post, $title, $local, $wikiId )
                                );

                                if ( $comment === null ) {
                                        $link = '';
                                        if ( $title ) {
                                                $section = $auto;
                                                # Remove links that a user may have manually put in the autosummary
                                                # This could be improved by copying as much of Parser::stripSectionName as desired.
                                                $section = str_replace( '[[:', '', $section );
                                                $section = str_replace( '[[', '', $section );
                                                $section = str_replace( ']]', '', $section );

                                                $section = Sanitizer::normalizeSectionNameWhitespace( $section ); # bug 22784
                                                if ( $local ) {
                                                        $sectionTitle = Title::newFromText( '#' . $section );
                                                } else {
                                                        $sectionTitle = Title::makeTitleSafe( $title->getNamespace(),
                                                                $title->getDBkey(), $section );
                                                }
                                                if ( $sectionTitle ) {
                                                        $link = Linker::makeCommentLink( $sectionTitle, $wgLang->getArrow(), $wikiId, 'noclasses' );
                                                } else {
                                                        $link = '';
                                                }
                                        }
                                        if ( $pre ) {
                                                # written summary $presep autocomment (summary /* section */)
                                                $pre = wfMessage( 'autocomment-prefix' )->inContentLanguage()->escaped();
                                        }
                                        if ( $post ) {
                                                # autocomment $postsep written summary (/* section */ summary)
                                                $auto .= wfMessage( 'colon-separator' )->inContentLanguage()->escaped();
                                        }
                                        $auto = '<span class="autocomment">' . $auto . '</span>';
                                        $comment = $pre . $link . $wgLang->getDirMark()
                                                . '<span dir="auto">' . $auto;
                                        $append .= '</span>';
                                }
                                return $comment;
                        },
                        $comment
                );
                return $comment . $append;
        }

        /**
         * Formats wiki links and media links in text; all other wiki formatting
         * is ignored
         *
         * @todo FIXME: Doesn't handle sub-links as in image thumb texts like the main parser
         * @param string $comment Text to format links in
         * @param Title|null $title An optional title object used to links to sections
         * @param bool $local Whether section links should refer to local page
         * @param string|null $wikiId Id of the wiki to link to (if not the local wiki),
         *  as used by WikiMap.
         *
         * @return string
         */
        public static function formatLinksInComment(
                $comment, $title = null, $local = false, $wikiId = null
        ) {
                return preg_replace_callback(
                        '/
                                \[\[
                                :? # ignore optional leading colon
                                ([^\]|]+) # 1. link target; page names cannot include ] or |
                                (?:\|
                                        # 2. a pipe-separated substring; only the last is captured
                                        # Stop matching at | and ]] without relying on backtracking.
                                        ((?:]?[^\]|])*+)
                                )*
                                \]\]
                                ([^[]*) # 3. link trail (the text up until the next link)
                        /x',
                        function ( $match ) use ( $title, $local, $wikiId ) {
                                global $wgContLang;

                                $medians = '(?:' . preg_quote( MWNamespace::getCanonicalName( NS_MEDIA ), '/' ) . '|';
                                $medians .= preg_quote( $wgContLang->getNsText( NS_MEDIA ), '/' ) . '):';

                                $comment = $match[0];

                                # fix up urlencoded title texts (copied from Parser::replaceInternalLinks)
                                if ( strpos( $match[1], '%' ) !== false ) {
                                        $match[1] = strtr(
                                                rawurldecode( $match[1] ),
                                                array( '<' => '&lt;', '>' => '&gt;' )
                                        );
                                }

                                # Handle link renaming [[foo|text]] will show link as "text"
                                if ( $match[2] != "" ) {
                                        $text = $match[2];
                                } else {
                                        $text = $match[1];
                                }
                                $submatch = array();
                                $thelink = null;
                                if ( preg_match( '/^' . $medians . '(.*)$/i', $match[1], $submatch ) ) {
                                        # Media link; trail not supported.
                                        $linkRegexp = '/\[\[(.*?)\]\]/';
                                        $title = Title::makeTitleSafe( NS_FILE, $submatch[1] );
                                        if ( $title ) {
                                                $thelink = Linker::makeMediaLinkObj( $title, $text );
                                        }
                                } else {
                                        # Other kind of link
                                        if ( preg_match( $wgContLang->linkTrail(), $match[3], $submatch ) ) {
                                                $trail = $submatch[1];
                                        } else {
                                                $trail = "";
                                        }
                                        $linkRegexp = '/\[\[(.*?)\]\]' . preg_quote( $trail, '/' ) . '/';
                                        if ( isset( $match[1][0] ) && $match[1][0] == ':' ) {
                                                $match[1] = substr( $match[1], 1 );
                                        }
                                        list( $inside, $trail ) = Linker::splitTrail( $trail );

                                        $linkText = $text;
                                        $linkTarget = Linker::normalizeSubpageLink( $title, $match[1], $linkText );

                                        $target = Title::newFromText( $linkTarget );
                                        if ( $target ) {
                                                if ( $target->getText() == '' && !$target->isExternal()
                                                        && !$local && $title
                                                ) {
                                                        $newTarget = clone ( $title );
                                                        $newTarget->setFragment( '#' . $target->getFragment() );
                                                        $target = $newTarget;
                                                }

                                                $thelink = Linker::makeCommentLink( $target, $linkText . $inside, $wikiId ) . $trail;
                                        }
                                }
                                if ( $thelink ) {
                                        // If the link is still valid, go ahead and replace it in!
                                        $comment = preg_replace(
                                                $linkRegexp,
                                                StringUtils::escapeRegexReplacement( $thelink ),
                                                $comment,
                                                1
                                        );
                                }

                                return $comment;
                        },
                        $comment
                );
        }

        /**
         * Generates a link to the given Title
         *
         * @note This is only public for technical reasons. It's not intended for use outside Linker.
         *
         * @param Title $title
         * @param string $text
         * @param string|null $wikiId Id of the wiki to link to (if not the local wiki),
         *  as used by WikiMap.
         * @param string|string[] $options See the $options parameter in Linker::link.
         *
         * @return string HTML link
         */
        public static function makeCommentLink(
                Title $title, $text, $wikiId = null, $options = array()
        ) {
                if ( $wikiId !== null && !$title->isExternal() ) {
                        $link = Linker::makeExternalLink(
                                WikiMap::getForeignURL(
                                        $wikiId,
                                        $title->getPrefixedText(),
                                        $title->getFragment()
                                ),
                                $text,
                                /* escape = */ false // Already escaped
                        );
                } else {
                        $link = Linker::link( $title, $text, array(), array(), $options );
                }

                return $link;
        }

        /**
         * @param Title $contextTitle
         * @param string $target
         * @param string $text
         * @return string
         */
        public static function normalizeSubpageLink( $contextTitle, $target, &$text ) {
                # Valid link forms:
                # Foobar -- normal
                # :Foobar -- override special treatment of prefix (images, language links)
                # /Foobar -- convert to CurrentPage/Foobar
                # /Foobar/ -- convert to CurrentPage/Foobar, strip the initial and final / from text
                # ../ -- convert to CurrentPage, from CurrentPage/CurrentSubPage
                # ../Foobar -- convert to CurrentPage/Foobar,
                #              (from CurrentPage/CurrentSubPage)
                # ../Foobar/ -- convert to CurrentPage/Foobar, use 'Foobar' as text
                #              (from CurrentPage/CurrentSubPage)

                $ret = $target; # default return value is no change

                # Some namespaces don't allow subpages,
                # so only perform processing if subpages are allowed
                if ( $contextTitle && MWNamespace::hasSubpages( $contextTitle->getNamespace() ) ) {
                        $hash = strpos( $target, '#' );
                        if ( $hash !== false ) {
                                $suffix = substr( $target, $hash );
                                $target = substr( $target, 0, $hash );
                        } else {
                                $suffix = '';
                        }
                        # bug 7425
                        $target = trim( $target );
                        # Look at the first character
                        if ( $target != '' && $target[0] === '/' ) {
                                # / at end means we don't want the slash to be shown
                                $m = array();
                                $trailingSlashes = preg_match_all( '%(/+)$%', $target, $m );
                                if ( $trailingSlashes ) {
                                        $noslash = $target = substr( $target, 1, -strlen( $m[0][0] ) );
                                } else {
                                        $noslash = substr( $target, 1 );
                                }

                                $ret = $contextTitle->getPrefixedText() . '/' . trim( $noslash ) . $suffix;
                                if ( $text === '' ) {
                                        $text = $target . $suffix;
                                } # this might be changed for ugliness reasons
                        } else {
                                # check for .. subpage backlinks
                                $dotdotcount = 0;
                                $nodotdot = $target;
                                while ( strncmp( $nodotdot, "../", 3 ) == 0 ) {
                                        ++$dotdotcount;
                                        $nodotdot = substr( $nodotdot, 3 );
                                }
                                if ( $dotdotcount > 0 ) {
                                        $exploded = explode( '/', $contextTitle->getPrefixedText() );
                                        if ( count( $exploded ) > $dotdotcount ) { # not allowed to go below top level page
                                                $ret = implode( '/', array_slice( $exploded, 0, -$dotdotcount ) );
                                                # / at the end means don't show full path
                                                if ( substr( $nodotdot, -1, 1 ) === '/' ) {
                                                        $nodotdot = rtrim( $nodotdot, '/' );
                                                        if ( $text === '' ) {
                                                                $text = $nodotdot . $suffix;
                                                        }
                                                }
                                                $nodotdot = trim( $nodotdot );
                                                if ( $nodotdot != '' ) {
                                                        $ret .= '/' . $nodotdot;
                                                }
                                                $ret .= $suffix;
                                        }
                                }
                        }
                }

                return $ret;
        }

        /**
         * Wrap a comment in standard punctuation and formatting if
         * it's non-empty, otherwise return empty string.
         *
         * @param string $comment
         * @param Title|null $title Title object (to generate link to section in autocomment) or null
         * @param bool $local Whether section links should refer to local page
         * @param string|null $wikiId Id (as used by WikiMap) of the wiki to generate links to.
         *  For use with external changes.
         *
         * @return string
         */
        public static function commentBlock(
                $comment, $title = null, $local = false, $wikiId = null
        ) {
                // '*' used to be the comment inserted by the software way back
                // in antiquity in case none was provided, here for backwards
                // compatibility, acc. to brion -ævar
                if ( $comment == '' || $comment == '*' ) {
                        return '';
                } else {
                        $formatted = self::formatComment( $comment, $title, $local, $wikiId );
                        $formatted = wfMessage( 'parentheses' )->rawParams( $formatted )->escaped();
                        return " <span class=\"comment\">$formatted</span>";
                }
        }

        /**
         * Wrap and format the given revision's comment block, if the current
         * user is allowed to view it.
         *
         * @param Revision $rev
         * @param bool $local Whether section links should refer to local page
         * @param bool $isPublic Show only if all users can see it
         * @return string HTML fragment
         */
        public static function revComment( Revision $rev, $local = false, $isPublic = false ) {
                if ( $rev->getComment( Revision::RAW ) == "" ) {
                        return "";
                }
                if ( $rev->isDeleted( Revision::DELETED_COMMENT ) && $isPublic ) {
                        $block = " <span class=\"comment\">" . wfMessage( 'rev-deleted-comment' )->escaped() . "</span>";
                } elseif ( $rev->userCan( Revision::DELETED_COMMENT ) ) {
                        $block = self::commentBlock( $rev->getComment( Revision::FOR_THIS_USER ),
                                $rev->getTitle(), $local );
                } else {
                        $block = " <span class=\"comment\">" . wfMessage( 'rev-deleted-comment' )->escaped() . "</span>";
                }
                if ( $rev->isDeleted( Revision::DELETED_COMMENT ) ) {
                        return " <span class=\"history-deleted\">$block</span>";
                }
                return $block;
        }

        /**
         * @param int $size
         * @return string
         */
        public static function formatRevisionSize( $size ) {
                if ( $size == 0 ) {
                        $stxt = wfMessage( 'historyempty' )->escaped();
                } else {
                        $stxt = wfMessage( 'nbytes' )->numParams( $size )->escaped();
                        $stxt = wfMessage( 'parentheses' )->rawParams( $stxt )->escaped();
                }
                return "<span class=\"history-size\">$stxt</span>";
        }

        /**
         * Add another level to the Table of Contents
         *
         * @return string
         */
        public static function tocIndent() {
                return "\n<ul>";
        }

        /**
         * Finish one or more sublevels on the Table of Contents
         *
         * @param int $level
         * @return string
         */
        public static function tocUnindent( $level ) {
                return "</li>\n" . str_repeat( "</ul>\n</li>\n", $level > 0 ? $level : 0 );
        }

        /**
         * parameter level defines if we are on an indentation level
         *
         * @param string $anchor
         * @param string $tocline
         * @param string $tocnumber
         * @param string $level
         * @param string|bool $sectionIndex
         * @return string
         */
        public static function tocLine( $anchor, $tocline, $tocnumber, $level, $sectionIndex = false ) {
                $classes = "toclevel-$level";
                if ( $sectionIndex !== false ) {
                        $classes .= " tocsection-$sectionIndex";
                }
                return "\n<li class=\"$classes\"><a href=\"#" .
                        $anchor . '"><span class="tocnumber">' .
                        $tocnumber . '</span> <span class="toctext">' .
                        $tocline . '</span></a>';
        }

        /**
         * End a Table Of Contents line.
         * tocUnindent() will be used instead if we're ending a line below
         * the new level.
         * @return string
         */
        public static function tocLineEnd() {
                return "</li>\n";
        }

        /**
         * Wraps the TOC in a table and provides the hide/collapse javascript.
         *
         * @param string $toc Html of the Table Of Contents
         * @param string|Language|bool $lang Language for the toc title, defaults to user language
         * @return string Full html of the TOC
         */
        public static function tocList( $toc, $lang = false ) {
                $lang = wfGetLangObj( $lang );
                $title = wfMessage( 'toc' )->inLanguage( $lang )->escaped();

                return '<div id="toc" class="toc">'
                        . '<div id="toctitle"><h2>' . $title . "</h2></div>\n"
                        . $toc
                        . "</ul>\n</div>\n";
        }

        /**
         * Generate a table of contents from a section tree.
         *
         * @param array $tree Return value of ParserOutput::getSections()
         * @param string|Language|bool $lang Language for the toc title, defaults to user language
         * @return string HTML fragment
         */
        public static function generateTOC( $tree, $lang = false ) {
                $toc = '';
                $lastLevel = 0;
                foreach ( $tree as $section ) {
                        if ( $section['toclevel'] > $lastLevel ) {
                                $toc .= self::tocIndent();
                        } elseif ( $section['toclevel'] < $lastLevel ) {
                                $toc .= self::tocUnindent(
                                        $lastLevel - $section['toclevel'] );
                        } else {
                                $toc .= self::tocLineEnd();
                        }

                        $toc .= self::tocLine( $section['anchor'],
                                $section['line'], $section['number'],
                                $section['toclevel'], $section['index'] );
                        $lastLevel = $section['toclevel'];
                }
                $toc .= self::tocLineEnd();
                return self::tocList( $toc, $lang );
        }

        /**
         * Create a headline for content
         *
         * @param int $level The level of the headline (1-6)
         * @param string $attribs Any attributes for the headline, starting with
         *   a space and ending with '>'
         *   This *must* be at least '>' for no attribs
         * @param string $anchor The anchor to give the headline (the bit after the #)
         * @param string $html Html for the text of the header
         * @param string $link HTML to add for the section edit link
         * @param bool|string $legacyAnchor A second, optional anchor to give for
         *   backward compatibility (false to omit)
         *
         * @return string HTML headline
         */
        public static function makeHeadline( $level, $attribs, $anchor, $html,
                $link, $legacyAnchor = false
        ) {
                $ret = "<h$level$attribs"
                        . "<span class=\"mw-headline\" id=\"$anchor\">$html</span>"
                        . $link
                        . "</h$level>";
                if ( $legacyAnchor !== false ) {
                        $ret = "<div id=\"$legacyAnchor\"></div>$ret";
                }
                return $ret;
        }

        /**
         * Split a link trail, return the "inside" portion and the remainder of the trail
         * as a two-element array
         * @param string $trail
         * @return array
         */
        static function splitTrail( $trail ) {
                global $wgContLang;
                $regex = $wgContLang->linkTrail();
                $inside = '';
                if ( $trail !== '' ) {
                        $m = array();
                        if ( preg_match( $regex, $trail, $m ) ) {
                                $inside = $m[1];
                                $trail = $m[2];
                        }
                }
                return array( $inside, $trail );
        }

        /**
         * Generate a rollback link for a given revision.  Currently it's the
         * caller's responsibility to ensure that the revision is the top one. If
         * it's not, of course, the user will get an error message.
         *
         * If the calling page is called with the parameter &bot=1, all rollback
         * links also get that parameter. It causes the edit itself and the rollback
         * to be marked as "bot" edits. Bot edits are hidden by default from recent
         * changes, so this allows sysops to combat a busy vandal without bothering
         * other users.
         *
         * If the option verify is set this function will return the link only in case the
         * revision can be reverted. Please note that due to performance limitations
         * it might be assumed that a user isn't the only contributor of a page while
         * (s)he is, which will lead to useless rollback links. Furthermore this wont
         * work if $wgShowRollbackEditCount is disabled, so this can only function
         * as an additional check.
         *
         * If the option noBrackets is set the rollback link wont be enclosed in []
         *
         * @param Revision $rev
         * @param IContextSource $context Context to use or null for the main context.
         * @param array $options
         * @return string
         */
        public static function generateRollback( $rev, IContextSource $context = null,
                $options = array( 'verify' )
        ) {
                if ( $context === null ) {
                        $context = RequestContext::getMain();
                }

                $editCount = false;
                if ( in_array( 'verify', $options ) ) {
                        $editCount = self::getRollbackEditCount( $rev, true );
                        if ( $editCount === false ) {
                                return '';
                        }
                }

                $inner = self::buildRollbackLink( $rev, $context, $editCount );

                if ( !in_array( 'noBrackets', $options ) ) {
                        $inner = $context->msg( 'brackets' )->rawParams( $inner )->escaped();
                }

                return '<span class="mw-rollback-link">' . $inner . '</span>';
        }

        /**
         * This function will return the number of revisions which a rollback
         * would revert and, if $verify is set it will verify that a revision
         * can be reverted (that the user isn't the only contributor and the
         * revision we might rollback to isn't deleted). These checks can only
         * function as an additional check as this function only checks against
         * the last $wgShowRollbackEditCount edits.
         *
         * Returns null if $wgShowRollbackEditCount is disabled or false if $verify
         * is set and the user is the only contributor of the page.
         *
         * @param Revision $rev
         * @param bool $verify Try to verify that this revision can really be rolled back
         * @return int|bool|null
         */
        public static function getRollbackEditCount( $rev, $verify ) {
                global $wgShowRollbackEditCount;
                if ( !is_int( $wgShowRollbackEditCount ) || !$wgShowRollbackEditCount > 0 ) {
                        // Nothing has happened, indicate this by returning 'null'
                        return null;
                }

                $dbr = wfGetDB( DB_SLAVE );

                // Up to the value of $wgShowRollbackEditCount revisions are counted
                $res = $dbr->select(
                        'revision',
                        array( 'rev_user_text', 'rev_deleted' ),
                        // $rev->getPage() returns null sometimes
                        array( 'rev_page' => $rev->getTitle()->getArticleID() ),
                        __METHOD__,
                        array(
                                'USE INDEX' => array( 'revision' => 'page_timestamp' ),
                                'ORDER BY' => 'rev_timestamp DESC',
                                'LIMIT' => $wgShowRollbackEditCount + 1
                        )
                );

                $editCount = 0;
                $moreRevs = false;
                foreach ( $res as $row ) {
                        if ( $rev->getUserText( Revision::RAW ) != $row->rev_user_text ) {
                                if ( $verify &&
                                        ( $row->rev_deleted & Revision::DELETED_TEXT
                                                || $row->rev_deleted & Revision::DELETED_USER
                                ) ) {
                                        // If the user or the text of the revision we might rollback
                                        // to is deleted in some way we can't rollback. Similar to
                                        // the sanity checks in WikiPage::commitRollback.
                                        return false;
                                }
                                $moreRevs = true;
                                break;
                        }
                        $editCount++;
                }

                if ( $verify && $editCount <= $wgShowRollbackEditCount && !$moreRevs ) {
                        // We didn't find at least $wgShowRollbackEditCount revisions made by the current user
                        // and there weren't any other revisions. That means that the current user is the only
                        // editor, so we can't rollback
                        return false;
                }
                return $editCount;
        }

        /**
         * Build a raw rollback link, useful for collections of "tool" links
         *
         * @param Revision $rev
         * @param IContextSource|null $context Context to use or null for the main context.
         * @param int $editCount Number of edits that would be reverted
         * @return string HTML fragment
         */
        public static function buildRollbackLink( $rev, IContextSource $context = null,
                $editCount = false
        ) {
                global $wgShowRollbackEditCount, $wgMiserMode;

                // To config which pages are affected by miser mode
                $disableRollbackEditCountSpecialPage = array( 'Recentchanges', 'Watchlist' );

                if ( $context === null ) {
                        $context = RequestContext::getMain();
                }

                $title = $rev->getTitle();
                $query = array(
                        'action' => 'rollback',
                        'from' => $rev->getUserText(),
                        'token' => $context->getUser()->getEditToken( array(
                                $title->getPrefixedText(),
                                $rev->getUserText()
                        ) ),
                );
                if ( $context->getRequest()->getBool( 'bot' ) ) {
                        $query['bot'] = '1';
                        $query['hidediff'] = '1'; // bug 15999
                }

                $disableRollbackEditCount = false;
                if ( $wgMiserMode ) {
                        foreach ( $disableRollbackEditCountSpecialPage as $specialPage ) {
                                if ( $context->getTitle()->isSpecial( $specialPage ) ) {
                                        $disableRollbackEditCount = true;
                                        break;
                                }
                        }
                }

                if ( !$disableRollbackEditCount
                        && is_int( $wgShowRollbackEditCount )
                        && $wgShowRollbackEditCount > 0
                ) {
                        if ( !is_numeric( $editCount ) ) {
                                $editCount = self::getRollbackEditCount( $rev, false );
                        }

                        if ( $editCount > $wgShowRollbackEditCount ) {
                                $editCount_output = $context->msg( 'rollbacklinkcount-morethan' )
                                        ->numParams( $wgShowRollbackEditCount )->parse();
                        } else {
                                $editCount_output = $context->msg( 'rollbacklinkcount' )->numParams( $editCount )->parse();
                        }

                        return self::link(
                                $title,
                                $editCount_output,
                                array( 'title' => $context->msg( 'tooltip-rollback' )->text() ),
                                $query,
                                array( 'known', 'noclasses' )
                        );
                } else {
                        return self::link(
                                $title,
                                $context->msg( 'rollbacklink' )->escaped(),
                                array( 'title' => $context->msg( 'tooltip-rollback' )->text() ),
                                $query,
                                array( 'known', 'noclasses' )
                        );
                }
        }

        /**
         * Returns HTML for the "templates used on this page" list.
         *
         * Make an HTML list of templates, and then add a "More..." link at
         * the bottom. If $more is null, do not add a "More..." link. If $more
         * is a Title, make a link to that title and use it. If $more is a string,
         * directly paste it in as the link (escaping needs to be done manually).
         * Finally, if $more is a Message, call toString().
         *
         * @param array $templates Array of templates from Article::getUsedTemplate or similar
         * @param bool $preview Whether this is for a preview
         * @param bool $section Whether this is for a section edit
         * @param Title|Message|string|null $more An escaped link for "More..." of the templates
         * @return string HTML output
         */
        public static function formatTemplates( $templates, $preview = false,
                $section = false, $more = null
        ) {
                global $wgLang;

                $outText = '';
                if ( count( $templates ) > 0 ) {
                        # Do a batch existence check
                        $batch = new LinkBatch;
                        foreach ( $templates as $title ) {
                                $batch->addObj( $title );
                        }
                        $batch->execute();

                        # Construct the HTML
                        $outText = '<div class="mw-templatesUsedExplanation">';
                        if ( $preview ) {
                                $outText .= wfMessage( 'templatesusedpreview' )->numParams( count( $templates ) )
                                        ->parseAsBlock();
                        } elseif ( $section ) {
                                $outText .= wfMessage( 'templatesusedsection' )->numParams( count( $templates ) )
                                        ->parseAsBlock();
                        } else {
                                $outText .= wfMessage( 'templatesused' )->numParams( count( $templates ) )
                                        ->parseAsBlock();
                        }
                        $outText .= "</div><ul>\n";

                        usort( $templates, 'Title::compare' );
                        foreach ( $templates as $titleObj ) {
                                $protected = '';
                                $restrictions = $titleObj->getRestrictions( 'edit' );
                                if ( $restrictions ) {
                                        // Check backwards-compatible messages
                                        $msg = null;
                                        if ( $restrictions === array( 'sysop' ) ) {
                                                $msg = wfMessage( 'template-protected' );
                                        } elseif ( $restrictions === array( 'autoconfirmed' ) ) {
                                                $msg = wfMessage( 'template-semiprotected' );
                                        }
                                        if ( $msg && !$msg->isDisabled() ) {
                                                $protected = $msg->parse();
                                        } else {
                                                // Construct the message from restriction-level-*
                                                // e.g. restriction-level-sysop, restriction-level-autoconfirmed
                                                $msgs = array();
                                                foreach ( $restrictions as $r ) {
                                                        $msgs[] = wfMessage( "restriction-level-$r" )->parse();
                                                }
                                                $protected = wfMessage( 'parentheses' )
                                                        ->rawParams( $wgLang->commaList( $msgs ) )->escaped();
                                        }
                                }
                                if ( $titleObj->quickUserCan( 'edit' ) ) {
                                        $editLink = self::link(
                                                $titleObj,
                                                wfMessage( 'editlink' )->escaped(),
                                                array(),
                                                array( 'action' => 'edit' )
                                        );
                                } else {
                                        $editLink = self::link(
                                                $titleObj,
                                                wfMessage( 'viewsourcelink' )->escaped(),
                                                array(),
                                                array( 'action' => 'edit' )
                                        );
                                }
                                $outText .= '<li>' . self::link( $titleObj )
                                        . wfMessage( 'word-separator' )->escaped()
                                        . wfMessage( 'parentheses' )->rawParams( $editLink )->escaped()
                                        . wfMessage( 'word-separator' )->escaped()
                                        . $protected . '</li>';
                        }

                        if ( $more instanceof Title ) {
                                $outText .= '<li>' . self::link( $more, wfMessage( 'moredotdotdot' ) ) . '</li>';
                        } elseif ( $more ) {
                                $outText .= "<li>$more</li>";
                        }

                        $outText .= '</ul>';
                }
                return $outText;
        }

        /**
         * Returns HTML for the "hidden categories on this page" list.
         *
         * @param array $hiddencats Array of hidden categories from Article::getHiddenCategories
         *   or similar
         * @return string HTML output
         */
        public static function formatHiddenCategories( $hiddencats ) {

                $outText = '';
                if ( count( $hiddencats ) > 0 ) {
                        # Construct the HTML
                        $outText = '<div class="mw-hiddenCategoriesExplanation">';
                        $outText .= wfMessage( 'hiddencategories' )->numParams( count( $hiddencats ) )->parseAsBlock();
                        $outText .= "</div><ul>\n";

                        foreach ( $hiddencats as $titleObj ) {
                                # If it's hidden, it must exist - no need to check with a LinkBatch
                                $outText .= '<li>'
                                        . self::link( $titleObj, null, array(), array(), 'known' )
                                        . "</li>\n";
                        }
                        $outText .= '</ul>';
                }
                return $outText;
        }

        /**
         * Format a size in bytes for output, using an appropriate
         * unit (B, KB, MB or GB) according to the magnitude in question
         *
         * @param int $size Size to format
         * @return string
         */
        public static function formatSize( $size ) {
                global $wgLang;
                return htmlspecialchars( $wgLang->formatSize( $size ) );
        }

        /**
         * Given the id of an interface element, constructs the appropriate title
         * attribute from the system messages.  (Note, this is usually the id but
         * isn't always, because sometimes the accesskey needs to go on a different
         * element than the id, for reverse-compatibility, etc.)
         *
         * @param string $name Id of the element, minus prefixes.
         * @param string|null $options Null or the string 'withaccess' to add an access-
         *   key hint
         * @return string Contents of the title attribute (which you must HTML-
         *   escape), or false for no title attribute
         */
        public static function titleAttrib( $name, $options = null ) {

                $message = wfMessage( "tooltip-$name" );

                if ( !$message->exists() ) {
                        $tooltip = false;
                } else {
                        $tooltip = $message->text();
                        # Compatibility: formerly some tooltips had [alt-.] hardcoded
                        $tooltip = preg_replace( "/ ?\[alt-.\]$/", '', $tooltip );
                        # Message equal to '-' means suppress it.
                        if ( $tooltip == '-' ) {
                                $tooltip = false;
                        }
                }

                if ( $options == 'withaccess' ) {
                        $accesskey = self::accesskey( $name );
                        if ( $accesskey !== false ) {
                                // Should be build the same as in jquery.accessKeyLabel.js
                                if ( $tooltip === false || $tooltip === '' ) {
                                        $tooltip = wfMessage( 'brackets', $accesskey )->text();
                                } else {
                                        $tooltip .= wfMessage( 'word-separator' )->text();
                                        $tooltip .= wfMessage( 'brackets', $accesskey )->text();
                                }
                        }
                }

                return $tooltip;
        }

        public static $accesskeycache;

        /**
         * Given the id of an interface element, constructs the appropriate
         * accesskey attribute from the system messages.  (Note, this is usually
         * the id but isn't always, because sometimes the accesskey needs to go on
         * a different element than the id, for reverse-compatibility, etc.)
         *
         * @param string $name Id of the element, minus prefixes.
         * @return string Contents of the accesskey attribute (which you must HTML-
         *   escape), or false for no accesskey attribute
         */
        public static function accesskey( $name ) {
                if ( isset( self::$accesskeycache[$name] ) ) {
                        return self::$accesskeycache[$name];
                }

                $message = wfMessage( "accesskey-$name" );

                if ( !$message->exists() ) {
                        $accesskey = false;
                } else {
                        $accesskey = $message->plain();
                        if ( $accesskey === '' || $accesskey === '-' ) {
                                # @todo FIXME: Per standard MW behavior, a value of '-' means to suppress the
                                # attribute, but this is broken for accesskey: that might be a useful
                                # value.
                                $accesskey = false;
                        }
                }

                self::$accesskeycache[$name] = $accesskey;
                return self::$accesskeycache[$name];
        }

        /**
         * Get a revision-deletion link, or disabled link, or nothing, depending
         * on user permissions & the settings on the revision.
         *
         * Will use forward-compatible revision ID in the Special:RevDelete link
         * if possible, otherwise the timestamp-based ID which may break after
         * undeletion.
         *
         * @param User $user
         * @param Revision $rev
         * @param Title $title
         * @return string HTML fragment
         */
        public static function getRevDeleteLink( User $user, Revision $rev, Title $title ) {
                $canHide = $user->isAllowed( 'deleterevision' );
                if ( !$canHide && !( $rev->getVisibility() && $user->isAllowed( 'deletedhistory' ) ) ) {
                        return '';
                }

                if ( !$rev->userCan( Revision::DELETED_RESTRICTED, $user ) ) {
                        return Linker::revDeleteLinkDisabled( $canHide ); // revision was hidden from sysops
                } else {
                        if ( $rev->getId() ) {
                                // RevDelete links using revision ID are stable across
                                // page deletion and undeletion; use when possible.
                                $query = array(
                                        'type' => 'revision',
                                        'target' => $title->getPrefixedDBkey(),
                                        'ids' => $rev->getId()
                                );
                        } else {
                                // Older deleted entries didn't save a revision ID.
                                // We have to refer to these by timestamp, ick!
                                $query = array(
                                        'type' => 'archive',
                                        'target' => $title->getPrefixedDBkey(),
                                        'ids' => $rev->getTimestamp()
                                );
                        }
                        return Linker::revDeleteLink( $query,
                                $rev->isDeleted( Revision::DELETED_RESTRICTED ), $canHide );
                }
        }

        /**
         * Creates a (show/hide) link for deleting revisions/log entries
         *
         * @param array $query Query parameters to be passed to link()
         * @param bool $restricted Set to true to use a "<strong>" instead of a "<span>"
         * @param bool $delete Set to true to use (show/hide) rather than (show)
         *
         * @return string HTML "<a>" link to Special:Revisiondelete, wrapped in a
         * span to allow for customization of appearance with CSS
         */
        public static function revDeleteLink( $query = array(), $restricted = false, $delete = true ) {
                $sp = SpecialPage::getTitleFor( 'Revisiondelete' );
                $msgKey = $delete ? 'rev-delundel' : 'rev-showdeleted';
                $html = wfMessage( $msgKey )->escaped();
                $tag = $restricted ? 'strong' : 'span';
                $link = self::link( $sp, $html, array(), $query, array( 'known', 'noclasses' ) );
                return Xml::tags(
                        $tag,
                        array( 'class' => 'mw-revdelundel-link' ),
                        wfMessage( 'parentheses' )->rawParams( $link )->escaped()
                );
        }

        /**
         * Creates a dead (show/hide) link for deleting revisions/log entries
         *
         * @param bool $delete Set to true to use (show/hide) rather than (show)
         *
         * @return string HTML text wrapped in a span to allow for customization
         * of appearance with CSS
         */
        public static function revDeleteLinkDisabled( $delete = true ) {
                $msgKey = $delete ? 'rev-delundel' : 'rev-showdeleted';
                $html = wfMessage( $msgKey )->escaped();
                $htmlParentheses = wfMessage( 'parentheses' )->rawParams( $html )->escaped();
                return Xml::tags( 'span', array( 'class' => 'mw-revdelundel-link' ), $htmlParentheses );
        }

        /* Deprecated methods */

        /**
         * @deprecated since 1.16 Use link(); warnings since 1.21
         *
         * Make a link for a title which may or may not be in the database. If you need to
         * call this lots of times, pre-fill the link cache with a LinkBatch, otherwise each
         * call to this will result in a DB query.
         *
         * @param Title $nt The title object to make the link from, e.g. from Title::newFromText.
         * @param string $text Link text
         * @param string $query Optional query part
         * @param string $trail Optional trail. Alphabetic characters at the start of this string will
         *   be included in the link text. Other characters will be appended after
         *   the end of the link.
         * @param string $prefix Optional prefix. As trail, only before instead of after.
         * @return string
         */
        static function makeLinkObj( $nt, $text = '', $query = '', $trail = '', $prefix = '' ) {
                wfDeprecated( __METHOD__, '1.21' );

                $query = wfCgiToArray( $query );
                list( $inside, $trail ) = self::splitTrail( $trail );
                if ( $text === '' ) {
                        $text = self::linkText( $nt );
                }

                $ret = self::link( $nt, "$prefix$text$inside", array(), $query ) . $trail;

                return $ret;
        }

        /**
         * @deprecated since 1.16 Use link(); warnings since 1.21
         *
         * Make a link for a title which definitely exists. This is faster than makeLinkObj because
         * it doesn't have to do a database query. It's also valid for interwiki titles and special
         * pages.
         *
         * @param Title $title Title object of target page
         * @param string $text Text to replace the title
         * @param string $query Link target
         * @param string $trail Text after link
         * @param string $prefix Text before link text
         * @param string $aprops Extra attributes to the a-element
         * @param string $style Style to apply - if empty, use getInternalLinkAttributesObj instead
         * @return string The a-element
         */
        static function makeKnownLinkObj(
                $title, $text = '', $query = '', $trail = '', $prefix = '', $aprops = '', $style = ''
        ) {
                wfDeprecated( __METHOD__, '1.21' );

                if ( $text == '' ) {
                        $text = self::linkText( $title );
                }
                $attribs = Sanitizer::mergeAttributes(
                        Sanitizer::decodeTagAttributes( $aprops ),
                        Sanitizer::decodeTagAttributes( $style )
                );
                $query = wfCgiToArray( $query );
                list( $inside, $trail ) = self::splitTrail( $trail );

                $ret = self::link( $title, "$prefix$text$inside", $attribs, $query,
                        array( 'known', 'noclasses' ) ) . $trail;

                return $ret;
        }

        /**
         * Returns the attributes for the tooltip and access key.
         * @param string $name
         * @return array
         */
        public static function tooltipAndAccesskeyAttribs( $name ) {
                # @todo FIXME: If Sanitizer::expandAttributes() treated "false" as "output
                # no attribute" instead of "output '' as value for attribute", this
                # would be three lines.
                $attribs = array(
                        'title' => self::titleAttrib( $name, 'withaccess' ),
                        'accesskey' => self::accesskey( $name )
                );
                if ( $attribs['title'] === false ) {
                        unset( $attribs['title'] );
                }
                if ( $attribs['accesskey'] === false ) {
                        unset( $attribs['accesskey'] );
                }
                return $attribs;
        }

        /**
         * Returns raw bits of HTML, use titleAttrib()
         * @param string $name
         * @param array|null $options
         * @return null|string
         */
        public static function tooltip( $name, $options = null ) {
                # @todo FIXME: If Sanitizer::expandAttributes() treated "false" as "output
                # no attribute" instead of "output '' as value for attribute", this
                # would be two lines.
                $tooltip = self::titleAttrib( $name, $options );
                if ( $tooltip === false ) {
                        return '';
                }
                return Xml::expandAttributes( array(
                        'title' => $tooltip
                ) );
        }

}

/**
 * @since 1.18
 */
class DummyLinker {

        /**
         * Use PHP's magic __call handler to transform instance calls to a dummy instance
         * into static calls to the new Linker for backwards compatibility.
         *
         * @param string $fname Name of called method
         * @param array $args Arguments to the method
         * @return mixed
         */
        public function __call( $fname, $args ) {
                return call_user_func_array( array( 'Linker', $fname ), $args );
        }
}