includes/CategoryViewer.php

   1 <?php
   2 /**
   3  * List and paging of category members.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22 use MediaWiki\MediaWikiServices;
  23
  24 class CategoryViewer extends ContextSource {
  25         /** @var int */
  26         public $limit;
  27
  28         /** @var array */
  29         public $from;
  30
  31         /** @var array */
  32         public $until;
  33
  34         /** @var string[] */
  35         public $articles;
  36
  37         /** @var array */
  38         public $articles_start_char;
  39
  40         /** @var array */
  41         public $children;
  42
  43         /** @var array */
  44         public $children_start_char;
  45
  46         /** @var bool */
  47         public $showGallery;
  48
  49         /** @var array */
  50         public $imgsNoGallery_start_char;
  51
  52         /** @var array */
  53         public $imgsNoGallery;
  54
  55         /** @var array */
  56         public $nextPage;
  57
  58         /** @var array */
  59         protected $prevPage;
  60
  61         /** @var array */
  62         public $flip;
  63
  64         /** @var Title */
  65         public $title;
  66
  67         /** @var Collation */
  68         public $collation;
  69
  70         /** @var ImageGallery */
  71         public $gallery;
  72
  73         /** @var Category Category object for this page. */
  74         private $cat;
  75
  76         /** @var array The original query array, to be used in generating paging links. */
  77         private $query;
  78
  79         /**
  80          * @since 1.19 $context is a second, required parameter
  81          * @param Title $title
  82          * @param IContextSource $context
  83          * @param array $from An array with keys page, subcat,
  84          *        and file for offset of results of each section (since 1.17)
  85          * @param array $until An array with 3 keys for until of each section (since 1.17)
  86          * @param array $query
  87          */
  88         function __construct( $title, IContextSource $context, $from = [],
  89                 $until = [], $query = []
  90         ) {
  91                 $this->title = $title;
  92                 $this->setContext( $context );
  93                 $this->getOutput()->addModuleStyles( [
  94                         'mediawiki.action.view.categoryPage.styles'
  95                 ] );
  96                 $this->from = $from;
  97                 $this->until = $until;
  98                 $this->limit = $context->getConfig()->get( 'CategoryPagingLimit' );
  99                 $this->cat = Category::newFromTitle( $title );
 100                 $this->query = $query;
 101                 $this->collation = Collation::singleton();
 102                 unset( $this->query['title'] );
 103         }
 104
 105         /**
 106          * Format the category data list.
 107          *
 108          * @return string HTML output
 109          */
 110         public function getHTML() {
 111
 112                 $this->showGallery = $this->getConfig()->get( 'CategoryMagicGallery' )
 113                         && !$this->getOutput()->mNoGallery;
 114
 115                 $this->clearCategoryState();
 116                 $this->doCategoryQuery();
 117                 $this->finaliseCategoryState();
 118
 119                 $r = $this->getSubcategorySection() .
 120                         $this->getPagesSection() .
 121                         $this->getImageSection();
 122
 123                 if ( $r == '' ) {
 124                         // If there is no category content to display, only
 125                         // show the top part of the navigation links.
 126                         // @todo FIXME: Cannot be completely suppressed because it
 127                         //        is unknown if 'until' or 'from' makes this
 128                         //        give 0 results.
 129                         $r = $r . $this->getCategoryTop();
 130                 } else {
 131                         $r = $this->getCategoryTop() .
 132                                 $r .
 133                                 $this->getCategoryBottom();
 134                 }
 135
 136                 // Give a proper message if category is empty
 137                 if ( $r == '' ) {
 138                         $r = $this->msg( 'category-empty' )->parseAsBlock();
 139                 }
 140
 141                 $lang = $this->getLanguage();
 142                 $attribs = [
 143                         'class' => 'mw-category-generated',
 144                         'lang' => $lang->getHtmlCode(),
 145                         'dir' => $lang->getDir()
 146                 ];
 147                 # put a div around the headings which are in the user language
 148                 $r = Html::openElement( 'div', $attribs ) . $r . '</div>';
 149
 150                 return $r;
 151         }
 152
 153         function clearCategoryState() {
 154                 $this->articles = [];
 155                 $this->articles_start_char = [];
 156                 $this->children = [];
 157                 $this->children_start_char = [];
 158                 if ( $this->showGallery ) {
 159                         // Note that null for mode is taken to mean use default.
 160                         $mode = $this->getRequest()->getVal( 'gallerymode', null );
 161                         try {
 162                                 $this->gallery = ImageGalleryBase::factory( $mode, $this->getContext() );
 163                         } catch ( Exception $e ) {
 164                                 // User specified something invalid, fallback to default.
 165                                 $this->gallery = ImageGalleryBase::factory( false, $this->getContext() );
 166                         }
 167
 168                         $this->gallery->setHideBadImages();
 169                 } else {
 170                         $this->imgsNoGallery = [];
 171                         $this->imgsNoGallery_start_char = [];
 172                 }
 173         }
 174
 175         /**
 176          * Add a subcategory to the internal lists, using a Category object
 177          * @param Category $cat
 178          * @param string $sortkey
 179          * @param int $pageLength
 180          */
 181         function addSubcategoryObject( Category $cat, $sortkey, $pageLength ) {
 182                 // Subcategory; strip the 'Category' namespace from the link text.
 183                 $title = $cat->getTitle();
 184
 185                 $this->children[] = $this->generateLink(
 186                         'subcat',
 187                         $title,
 188                         $title->isRedirect(),
 189                         htmlspecialchars( $title->getText() )
 190                 );
 191
 192                 $this->children_start_char[] =
 193                         $this->getSubcategorySortChar( $cat->getTitle(), $sortkey );
 194         }
 195
 196         function generateLink( $type, Title $title, $isRedirect, $html = null ) {
 197                 $link = null;
 198                 Hooks::run( 'CategoryViewer::generateLink', [ $type, $title, $html, &$link ] );
 199                 if ( $link === null ) {
 200                         $linkRenderer = MediaWikiServices::getInstance()->getLinkRenderer();
 201                         if ( $html !== null ) {
 202                                 $html = new HtmlArmor( $html );
 203                         }
 204                         $link = $linkRenderer->makeLink( $title, $html );
 205                 }
 206                 if ( $isRedirect ) {
 207                         $link = '<span class="redirect-in-category">' . $link . '</span>';
 208                 }
 209
 210                 return $link;
 211         }
 212
 213         /**
 214          * Get the character to be used for sorting subcategories.
 215          * If there's a link from Category:A to Category:B, the sortkey of the resulting
 216          * entry in the categorylinks table is Category:A, not A, which it SHOULD be.
 217          * Workaround: If sortkey == "Category:".$title, than use $title for sorting,
 218          * else use sortkey...
 219          *
 220          * @param Title $title
 221          * @param string $sortkey The human-readable sortkey (before transforming to icu or whatever).
 222          * @return string
 223          */
 224         function getSubcategorySortChar( $title, $sortkey ) {
 225                 global $wgContLang;
 226
 227                 if ( $title->getPrefixedText() == $sortkey ) {
 228                         $word = $title->getDBkey();
 229                 } else {
 230                         $word = $sortkey;
 231                 }
 232
 233                 $firstChar = $this->collation->getFirstLetter( $word );
 234
 235                 return $wgContLang->convert( $firstChar );
 236         }
 237
 238         /**
 239          * Add a page in the image namespace
 240          * @param Title $title
 241          * @param string $sortkey
 242          * @param int $pageLength
 243          * @param bool $isRedirect
 244          */
 245         function addImage( Title $title, $sortkey, $pageLength, $isRedirect = false ) {
 246                 global $wgContLang;
 247                 if ( $this->showGallery ) {
 248                         $flip = $this->flip['file'];
 249                         if ( $flip ) {
 250                                 $this->gallery->insert( $title );
 251                         } else {
 252                                 $this->gallery->add( $title );
 253                         }
 254                 } else {
 255                         $this->imgsNoGallery[] = $this->generateLink( 'image', $title, $isRedirect );
 256
 257                         $this->imgsNoGallery_start_char[] = $wgContLang->convert(
 258                                 $this->collation->getFirstLetter( $sortkey ) );
 259                 }
 260         }
 261
 262         /**
 263          * Add a miscellaneous page
 264          * @param Title $title
 265          * @param string $sortkey
 266          * @param int $pageLength
 267          * @param bool $isRedirect
 268          */
 269         function addPage( $title, $sortkey, $pageLength, $isRedirect = false ) {
 270                 global $wgContLang;
 271
 272                 $this->articles[] = $this->generateLink( 'page', $title, $isRedirect );
 273
 274                 $this->articles_start_char[] = $wgContLang->convert(
 275                         $this->collation->getFirstLetter( $sortkey ) );
 276         }
 277
 278         function finaliseCategoryState() {
 279                 if ( $this->flip['subcat'] ) {
 280                         $this->children = array_reverse( $this->children );
 281                         $this->children_start_char = array_reverse( $this->children_start_char );
 282                 }
 283                 if ( $this->flip['page'] ) {
 284                         $this->articles = array_reverse( $this->articles );
 285                         $this->articles_start_char = array_reverse( $this->articles_start_char );
 286                 }
 287                 if ( !$this->showGallery && $this->flip['file'] ) {
 288                         $this->imgsNoGallery = array_reverse( $this->imgsNoGallery );
 289                         $this->imgsNoGallery_start_char = array_reverse( $this->imgsNoGallery_start_char );
 290                 }
 291         }
 292
 293         function doCategoryQuery() {
 294                 $dbr = wfGetDB( DB_REPLICA, 'category' );
 295
 296                 $this->nextPage = [
 297                         'page' => null,
 298                         'subcat' => null,
 299                         'file' => null,
 300                 ];
 301                 $this->prevPage = [
 302                         'page' => null,
 303                         'subcat' => null,
 304                         'file' => null,
 305                 ];
 306
 307                 $this->flip = [ 'page' => false, 'subcat' => false, 'file' => false ];
 308
 309                 foreach ( [ 'page', 'subcat', 'file' ] as $type ) {
 310                         # Get the sortkeys for start/end, if applicable.  Note that if
 311                         # the collation in the database differs from the one
 312                         # set in $wgCategoryCollation, pagination might go totally haywire.
 313                         $extraConds = [ 'cl_type' => $type ];
 314                         if ( isset( $this->from[$type] ) && $this->from[$type] !== null ) {
 315                                 $extraConds[] = 'cl_sortkey >= '
 316                                         . $dbr->addQuotes( $this->collation->getSortKey( $this->from[$type] ) );
 317                         } elseif ( isset( $this->until[$type] ) && $this->until[$type] !== null ) {
 318                                 $extraConds[] = 'cl_sortkey < '
 319                                         . $dbr->addQuotes( $this->collation->getSortKey( $this->until[$type] ) );
 320                                 $this->flip[$type] = true;
 321                         }
 322
 323                         $res = $dbr->select(
 324                                 [ 'page', 'categorylinks', 'category' ],
 325                                 array_merge(
 326                                         LinkCache::getSelectFields(),
 327                                         [
 328                                                 'page_namespace',
 329                                                 'page_title',
 330                                                 'cl_sortkey',
 331                                                 'cat_id',
 332                                                 'cat_title',
 333                                                 'cat_subcats',
 334                                                 'cat_pages',
 335                                                 'cat_files',
 336                                                 'cl_sortkey_prefix',
 337                                                 'cl_collation'
 338                                         ]
 339                                 ),
 340                                 array_merge( [ 'cl_to' => $this->title->getDBkey() ], $extraConds ),
 341                                 __METHOD__,
 342                                 [
 343                                         'USE INDEX' => [ 'categorylinks' => 'cl_sortkey' ],
 344                                         'LIMIT' => $this->limit + 1,
 345                                         'ORDER BY' => $this->flip[$type] ? 'cl_sortkey DESC' : 'cl_sortkey',
 346                                 ],
 347                                 [
 348                                         'categorylinks' => [ 'INNER JOIN', 'cl_from = page_id' ],
 349                                         'category' => [ 'LEFT JOIN', [
 350                                                 'cat_title = page_title',
 351                                                 'page_namespace' => NS_CATEGORY
 352                                         ] ]
 353                                 ]
 354                         );
 355
 356                         Hooks::run( 'CategoryViewer::doCategoryQuery', [ $type, $res ] );
 357                         $linkCache = MediaWikiServices::getInstance()->getLinkCache();
 358
 359                         $count = 0;
 360                         foreach ( $res as $row ) {
 361                                 $title = Title::newFromRow( $row );
 362                                 $linkCache->addGoodLinkObjFromRow( $title, $row );
 363
 364                                 if ( $row->cl_collation === '' ) {
 365                                         // Hack to make sure that while updating from 1.16 schema
 366                                         // and db is inconsistent, that the sky doesn't fall.
 367                                         // See r83544. Could perhaps be removed in a couple decades...
 368                                         $humanSortkey = $row->cl_sortkey;
 369                                 } else {
 370                                         $humanSortkey = $title->getCategorySortkey( $row->cl_sortkey_prefix );
 371                                 }
 372
 373                                 if ( ++$count > $this->limit ) {
 374                                         # We've reached the one extra which shows that there
 375                                         # are additional pages to be had. Stop here...
 376                                         $this->nextPage[$type] = $humanSortkey;
 377                                         break;
 378                                 }
 379                                 if ( $count == $this->limit ) {
 380                                         $this->prevPage[$type] = $humanSortkey;
 381                                 }
 382
 383                                 if ( $title->getNamespace() == NS_CATEGORY ) {
 384                                         $cat = Category::newFromRow( $row, $title );
 385                                         $this->addSubcategoryObject( $cat, $humanSortkey, $row->page_len );
 386                                 } elseif ( $title->getNamespace() == NS_FILE ) {
 387                                         $this->addImage( $title, $humanSortkey, $row->page_len, $row->page_is_redirect );
 388                                 } else {
 389                                         $this->addPage( $title, $humanSortkey, $row->page_len, $row->page_is_redirect );
 390                                 }
 391                         }
 392                 }
 393         }
 394
 395         /**
 396          * @return string
 397          */
 398         function getCategoryTop() {
 399                 $r = $this->getCategoryBottom();
 400                 return $r === ''
 401                         ? $r
 402                         : "<br style=\"clear:both;\"/>\n" . $r;
 403         }
 404
 405         /**
 406          * @return string
 407          */
 408         function getSubcategorySection() {
 409                 # Don't show subcategories section if there are none.
 410                 $r = '';
 411                 $rescnt = count( $this->children );
 412                 $dbcnt = $this->cat->getSubcatCount();
 413                 // This function should be called even if the result isn't used, it has side-effects
 414                 $countmsg = $this->getCountMessage( $rescnt, $dbcnt, 'subcat' );
 415
 416                 if ( $rescnt > 0 ) {
 417                         # Showing subcategories
 418                         $r .= "<div id=\"mw-subcategories\">\n";
 419                         $r .= '<h2>' . $this->msg( 'subcategories' )->parse() . "</h2>\n";
 420                         $r .= $countmsg;
 421                         $r .= $this->getSectionPagingLinks( 'subcat' );
 422                         $r .= $this->formatList( $this->children, $this->children_start_char );
 423                         $r .= $this->getSectionPagingLinks( 'subcat' );
 424                         $r .= "\n</div>";
 425                 }
 426                 return $r;
 427         }
 428
 429         /**
 430          * @return string
 431          */
 432         function getPagesSection() {
 433                 $ti = wfEscapeWikiText( $this->title->getText() );
 434                 # Don't show articles section if there are none.
 435                 $r = '';
 436
 437                 # @todo FIXME: Here and in the other two sections: we don't need to bother
 438                 # with this rigmarole if the entire category contents fit on one page
 439                 # and have already been retrieved.  We can just use $rescnt in that
 440                 # case and save a query and some logic.
 441                 $dbcnt = $this->cat->getPageCount() - $this->cat->getSubcatCount()
 442                         - $this->cat->getFileCount();
 443                 $rescnt = count( $this->articles );
 444                 // This function should be called even if the result isn't used, it has side-effects
 445                 $countmsg = $this->getCountMessage( $rescnt, $dbcnt, 'article' );
 446
 447                 if ( $rescnt > 0 ) {
 448                         $r = "<div id=\"mw-pages\">\n";
 449                         $r .= '<h2>' . $this->msg( 'category_header', $ti )->parse() . "</h2>\n";
 450                         $r .= $countmsg;
 451                         $r .= $this->getSectionPagingLinks( 'page' );
 452                         $r .= $this->formatList( $this->articles, $this->articles_start_char );
 453                         $r .= $this->getSectionPagingLinks( 'page' );
 454                         $r .= "\n</div>";
 455                 }
 456                 return $r;
 457         }
 458
 459         /**
 460          * @return string
 461          */
 462         function getImageSection() {
 463                 $r = '';
 464                 $rescnt = $this->showGallery ? $this->gallery->count() : count( $this->imgsNoGallery );
 465                 $dbcnt = $this->cat->getFileCount();
 466                 // This function should be called even if the result isn't used, it has side-effects
 467                 $countmsg = $this->getCountMessage( $rescnt, $dbcnt, 'file' );
 468
 469                 if ( $rescnt > 0 ) {
 470                         $r .= "<div id=\"mw-category-media\">\n";
 471                         $r .= '<h2>' .
 472                                 $this->msg(
 473                                         'category-media-header',
 474                                         wfEscapeWikiText( $this->title->getText() )
 475                                 )->text() .
 476                                 "</h2>\n";
 477                         $r .= $countmsg;
 478                         $r .= $this->getSectionPagingLinks( 'file' );
 479                         if ( $this->showGallery ) {
 480                                 $r .= $this->gallery->toHTML();
 481                         } else {
 482                                 $r .= $this->formatList( $this->imgsNoGallery, $this->imgsNoGallery_start_char );
 483                         }
 484                         $r .= $this->getSectionPagingLinks( 'file' );
 485                         $r .= "\n</div>";
 486                 }
 487                 return $r;
 488         }
 489
 490         /**
 491          * Get the paging links for a section (subcats/pages/files), to go at the top and bottom
 492          * of the output.
 493          *
 494          * @param string $type 'page', 'subcat', or 'file'
 495          * @return string HTML output, possibly empty if there are no other pages
 496          */
 497         private function getSectionPagingLinks( $type ) {
 498                 if ( isset( $this->until[$type] ) && $this->until[$type] !== null ) {
 499                         // The new value for the until parameter should be pointing to the first
 500                         // result displayed on the page which is the second last result retrieved
 501                         // from the database.The next link should have a from parameter pointing
 502                         // to the until parameter of the current page.
 503                         if ( $this->nextPage[$type] !== null ) {
 504                                 return $this->pagingLinks( $this->prevPage[$type], $this->until[$type], $type );
 505                         } else {
 506                                 // If the nextPage variable is null, it means that we have reached the first page
 507                                 // and therefore the previous link should be disabled.
 508                                 return $this->pagingLinks( null, $this->until[$type], $type );
 509                         }
 510                 } elseif ( $this->nextPage[$type] !== null
 511                         || ( isset( $this->from[$type] ) && $this->from[$type] !== null )
 512                 ) {
 513                         return $this->pagingLinks( $this->from[$type], $this->nextPage[$type], $type );
 514                 } else {
 515                         return '';
 516                 }
 517         }
 518
 519         /**
 520          * @return string
 521          */
 522         function getCategoryBottom() {
 523                 return '';
 524         }
 525
 526         /**
 527          * Format a list of articles chunked by letter, either as a
 528          * bullet list or a columnar format, depending on the length.
 529          *
 530          * @param array $articles
 531          * @param array $articles_start_char
 532          * @param int $cutoff
 533          * @return string
 534          * @private
 535          */
 536         function formatList( $articles, $articles_start_char, $cutoff = 6 ) {
 537                 $list = '';
 538                 if ( count( $articles ) > $cutoff ) {
 539                         $list = self::columnList( $articles, $articles_start_char );
 540                 } elseif ( count( $articles ) > 0 ) {
 541                         // for short lists of articles in categories.
 542                         $list = self::shortList( $articles, $articles_start_char );
 543                 }
 544
 545                 $pageLang = $this->title->getPageLanguage();
 546                 $attribs = [ 'lang' => $pageLang->getHtmlCode(), 'dir' => $pageLang->getDir(),
 547                         'class' => 'mw-content-' . $pageLang->getDir() ];
 548                 $list = Html::rawElement( 'div', $attribs, $list );
 549
 550                 return $list;
 551         }
 552
 553         /**
 554          * Format a list of articles chunked by letter in a three-column list, ordered
 555          * vertically. This is used for categories with a significant number of pages.
 556          *
 557          * TODO: Take the headers into account when creating columns, so they're
 558          * more visually equal.
 559          *
 560          * TODO: shortList and columnList are similar, need merging
 561          *
 562          * @param string[] $articles HTML links to each article
 563          * @param string[] $articles_start_char The header characters for each article
 564          * @return string HTML to output
 565          * @private
 566          */
 567         static function columnList( $articles, $articles_start_char ) {
 568                 $columns = array_combine( $articles, $articles_start_char );
 569
 570                 $ret = Html::openElement( 'div', [ 'class' => 'mw-category' ] );
 571
 572                 $colContents = [];
 573
 574                 # Kind of like array_flip() here, but we keep duplicates in an
 575                 # array instead of dropping them.
 576                 foreach ( $columns as $article => $char ) {
 577                         if ( !isset( $colContents[$char] ) ) {
 578                                 $colContents[$char] = [];
 579                         }
 580                         $colContents[$char][] = $article;
 581                 }
 582
 583                 foreach ( $colContents as $char => $articles ) {
 584                         # Change space to non-breaking space to keep headers aligned
 585                         $h3char = $char === ' ' ? '&#160;' : htmlspecialchars( $char );
 586
 587                         $ret .= '<div class="mw-category-group"><h3>' . $h3char;
 588                         $ret .= "</h3>\n";
 589
 590                         $ret .= '<ul><li>';
 591                         $ret .= implode( "</li>\n<li>", $articles );
 592                         $ret .= '</li></ul></div>';
 593
 594                 }
 595
 596                 $ret .= Html::closeElement( 'div' );
 597                 return $ret;
 598         }
 599
 600         /**
 601          * Format a list of articles chunked by letter in a bullet list. This is used
 602          * for categories with a small number of pages (when columns aren't needed).
 603          * @param string[] $articles HTML links to each article
 604          * @param string[] $articles_start_char The header characters for each article
 605          * @return string HTML to output
 606          * @private
 607          */
 608         static function shortList( $articles, $articles_start_char ) {
 609                 $r = '<h3>' . htmlspecialchars( $articles_start_char[0] ) . "</h3>\n";
 610                 $r .= '<ul><li>' . $articles[0] . '</li>';
 611                 $articleCount = count( $articles );
 612                 for ( $index = 1; $index < $articleCount; $index++ ) {
 613                         if ( $articles_start_char[$index] != $articles_start_char[$index - 1] ) {
 614                                 $r .= "</ul><h3>" . htmlspecialchars( $articles_start_char[$index] ) . "</h3>\n<ul>";
 615                         }
 616
 617                         $r .= "<li>{$articles[$index]}</li>";
 618                 }
 619                 $r .= '</ul>';
 620                 return $r;
 621         }
 622
 623         /**
 624          * Create paging links, as a helper method to getSectionPagingLinks().
 625          *
 626          * @param string $first The 'until' parameter for the generated URL
 627          * @param string $last The 'from' parameter for the generated URL
 628          * @param string $type A prefix for parameters, 'page' or 'subcat' or
 629          *     'file'
 630          * @return string HTML
 631          */
 632         private function pagingLinks( $first, $last, $type = '' ) {
 633                 $prevLink = $this->msg( 'prev-page' )->text();
 634
 635                 if ( $first != '' ) {
 636                         $prevQuery = $this->query;
 637                         $prevQuery["{$type}until"] = $first;
 638                         unset( $prevQuery["{$type}from"] );
 639                         $prevLink = Linker::linkKnown(
 640                                 $this->addFragmentToTitle( $this->title, $type ),
 641                                 $prevLink,
 642                                 [],
 643                                 $prevQuery
 644                         );
 645                 }
 646
 647                 $nextLink = $this->msg( 'next-page' )->text();
 648
 649                 if ( $last != '' ) {
 650                         $lastQuery = $this->query;
 651                         $lastQuery["{$type}from"] = $last;
 652                         unset( $lastQuery["{$type}until"] );
 653                         $nextLink = Linker::linkKnown(
 654                                 $this->addFragmentToTitle( $this->title, $type ),
 655                                 $nextLink,
 656                                 [],
 657                                 $lastQuery
 658                         );
 659                 }
 660
 661                 return $this->msg( 'categoryviewer-pagedlinks' )->rawParams( $prevLink, $nextLink )->escaped();
 662         }
 663
 664         /**
 665          * Takes a title, and adds the fragment identifier that
 666          * corresponds to the correct segment of the category.
 667          *
 668          * @param Title $title The title (usually $this->title)
 669          * @param string $section Which section
 670          * @throws MWException
 671          * @return Title
 672          */
 673         private function addFragmentToTitle( $title, $section ) {
 674                 switch ( $section ) {
 675                         case 'page':
 676                                 $fragment = 'mw-pages';
 677                                 break;
 678                         case 'subcat':
 679                                 $fragment = 'mw-subcategories';
 680                                 break;
 681                         case 'file':
 682                                 $fragment = 'mw-category-media';
 683                                 break;
 684                         default:
 685                                 throw new MWException( __METHOD__ .
 686                                         " Invalid section $section." );
 687                 }
 688
 689                 return Title::makeTitle( $title->getNamespace(),
 690                         $title->getDBkey(), $fragment );
 691         }
 692
 693         /**
 694          * What to do if the category table conflicts with the number of results
 695          * returned?  This function says what. Each type is considered independently
 696          * of the other types.
 697          *
 698          * @param int $rescnt The number of items returned by our database query.
 699          * @param int $dbcnt The number of items according to the category table.
 700          * @param string $type 'subcat', 'article', or 'file'
 701          * @return string A message giving the number of items, to output to HTML.
 702          */
 703         private function getCountMessage( $rescnt, $dbcnt, $type ) {
 704                 // There are three cases:
 705                 //   1) The category table figure seems sane.  It might be wrong, but
 706                 //      we can't do anything about it if we don't recalculate it on ev-
 707                 //      ery category view.
 708                 //   2) The category table figure isn't sane, like it's smaller than the
 709                 //      number of actual results, *but* the number of results is less
 710                 //      than $this->limit and there's no offset.  In this case we still
 711                 //      know the right figure.
 712                 //   3) We have no idea.
 713
 714                 // Check if there's a "from" or "until" for anything
 715
 716                 // This is a little ugly, but we seem to use different names
 717                 // for the paging types then for the messages.
 718                 if ( $type === 'article' ) {
 719                         $pagingType = 'page';
 720                 } else {
 721                         $pagingType = $type;
 722                 }
 723
 724                 $fromOrUntil = false;
 725                 if ( ( isset( $this->from[$pagingType] ) && $this->from[$pagingType] !== null ) ||
 726                         ( isset( $this->until[$pagingType] ) && $this->until[$pagingType] !== null )
 727                 ) {
 728                         $fromOrUntil = true;
 729                 }
 730
 731                 if ( $dbcnt == $rescnt ||
 732                         ( ( $rescnt == $this->limit || $fromOrUntil ) && $dbcnt > $rescnt )
 733                 ) {
 734                         // Case 1: seems sane.
 735                         $totalcnt = $dbcnt;
 736                 } elseif ( $rescnt < $this->limit && !$fromOrUntil ) {
 737                         // Case 2: not sane, but salvageable.  Use the number of results.
 738                         // Since there are fewer than 200, we can also take this opportunity
 739                         // to refresh the incorrect category table entry -- which should be
 740                         // quick due to the small number of entries.
 741                         $totalcnt = $rescnt;
 742                         $category = $this->cat;
 743                         DeferredUpdates::addCallableUpdate( function () use ( $category ) {
 744                                 $category->refreshCounts();
 745                         } );
 746                 } else {
 747                         // Case 3: hopeless.  Don't give a total count at all.
 748                         // Messages: category-subcat-count-limited, category-article-count-limited,
 749                         // category-file-count-limited
 750                         return $this->msg( "category-$type-count-limited" )->numParams( $rescnt )->parseAsBlock();
 751                 }
 752                 // Messages: category-subcat-count, category-article-count, category-file-count
 753                 return $this->msg( "category-$type-count" )->numParams( $rescnt, $totalcnt )->parseAsBlock();
 754         }
 755 }