includes/HistoryPage.php

   1 <?php
   2 /**
   3  * Page history
   4  *
   5  * Split off from Article.php and Skin.php, 2003-12-22
   6  * @file
   7  */
   8
   9 /**
  10  * This class handles printing the history page for an article.  In order to
  11  * be efficient, it uses timestamps rather than offsets for paging, to avoid
  12  * costly LIMIT,offset queries.
  13  *
  14  * Construct it by passing in an Article, and call $h->history() to print the
  15  * history.
  16  *
  17  */
  18 class HistoryPage {
  19         const DIR_PREV = 0;
  20         const DIR_NEXT = 1;
  21
  22         var $article, $title, $skin;
  23
  24         /**
  25          * Construct a new HistoryPage.
  26          *
  27          * @param Article $article
  28          * @returns nothing
  29          */
  30         function __construct( $article ) {
  31                 global $wgUser;
  32                 $this->article = $article;
  33                 $this->title = $article->getTitle();
  34                 $this->skin = $wgUser->getSkin();
  35                 $this->preCacheMessages();
  36         }
  37
  38         function getArticle() {
  39                 return $this->article;
  40         }
  41
  42         function getTitle() {
  43                 return $this->title;
  44         }
  45
  46         /**
  47          * As we use the same small set of messages in various methods and that
  48          * they are called often, we call them once and save them in $this->message
  49          */
  50         function preCacheMessages() {
  51                 // Precache various messages
  52                 if( !isset( $this->message ) ) {
  53                         foreach( explode(' ', 'cur last rev-delundel' ) as $msg ) {
  54                                 $this->message[$msg] = wfMsgExt( $msg, array( 'escape') );
  55                         }
  56                 }
  57         }
  58
  59         /**
  60          * Print the history page for an article.
  61          *
  62          * @returns nothing
  63          */
  64         function history() {
  65                 global $wgOut, $wgRequest, $wgScript;
  66
  67                 /*
  68                  * Allow client caching.
  69                  */
  70                 if( $wgOut->checkLastModified( $this->article->getTouched() ) )
  71                         return; // Client cache fresh and headers sent, nothing more to do.
  72
  73                 wfProfileIn( __METHOD__ );
  74
  75                 /*
  76                  * Setup page variables.
  77                  */
  78                 $wgOut->setPageTitle( wfMsg( 'history-title', $this->title->getPrefixedText() ) );
  79                 $wgOut->setPageTitleActionText( wfMsg( 'history_short' ) );
  80                 $wgOut->setArticleFlag( false );
  81                 $wgOut->setArticleRelated( true );
  82                 $wgOut->setRobotPolicy( 'noindex,nofollow' );
  83                 $wgOut->setSyndicated( true );
  84                 $wgOut->setFeedAppendQuery( 'action=history' );
  85                 $wgOut->addScriptFile( 'history.js' );
  86
  87                 $logPage = SpecialPage::getTitleFor( 'Log' );
  88                 $logLink = $this->skin->link(
  89                         $logPage,
  90                         wfMsgHtml( 'viewpagelogs' ),
  91                         array(),
  92                         array( 'page' => $this->title->getPrefixedText() ),
  93                         array( 'known', 'noclasses' )
  94                 );
  95                 $wgOut->setSubtitle( $logLink );
  96
  97                 $feedType = $wgRequest->getVal( 'feed' );
  98                 if( $feedType ) {
  99                         wfProfileOut( __METHOD__ );
 100                         return $this->feed( $feedType );
 101                 }
 102
 103                 /*
 104                  * Fail if article doesn't exist.
 105                  */
 106                 if( !$this->title->exists() ) {
 107                         $wgOut->addWikiMsg( 'nohistory' );
 108                         wfProfileOut( __METHOD__ );
 109                         return;
 110                 }
 111
 112                 /**
 113                  * Add date selector to quickly get to a certain time
 114                  */
 115                 $year = $wgRequest->getInt( 'year' );
 116                 $month = $wgRequest->getInt( 'month' );
 117                 $tagFilter = $wgRequest->getVal( 'tagfilter' );
 118                 $tagSelector = ChangeTags::buildTagFilterSelector( $tagFilter );
 119
 120                 $action = htmlspecialchars( $wgScript );
 121                 $wgOut->addHTML(
 122                         "<form action=\"$action\" method=\"get\" id=\"mw-history-searchform\">" .
 123                         Xml::fieldset( wfMsg( 'history-fieldset-title' ), false, array( 'id' => 'mw-history-search' ) ) .
 124                         Xml::hidden( 'title', $this->title->getPrefixedDBKey() ) . "\n" .
 125                         Xml::hidden( 'action', 'history' ) . "\n" .
 126                         xml::dateMenu( $year, $month ) . '&nbsp;' .
 127                         ( $tagSelector ? ( implode( '&nbsp;', $tagSelector ) . '&nbsp;' ) : '' ) .
 128                         Xml::submitButton( wfMsg( 'allpagessubmit' ) ) . "\n" .
 129                         '</fieldset></form>'
 130                 );
 131
 132                 wfRunHooks( 'PageHistoryBeforeList', array( &$this->article ) );
 133
 134                 /**
 135                  * Do the list
 136                  */
 137                 $pager = new HistoryPager( $this, $year, $month, $tagFilter );
 138                 $wgOut->addHTML(
 139                         $pager->getNavigationBar() .
 140                         $pager->getBody() .
 141                         $pager->getNavigationBar()
 142                 );
 143
 144                 wfProfileOut( __METHOD__ );
 145         }
 146
 147         /**
 148          * Fetch an array of revisions, specified by a given limit, offset and
 149          * direction. This is now only used by the feeds. It was previously
 150          * used by the main UI but that's now handled by the pager.
 151          */
 152         function fetchRevisions($limit, $offset, $direction) {
 153                 $dbr = wfGetDB( DB_SLAVE );
 154
 155                 if( $direction == HistoryPage::DIR_PREV )
 156                         list($dirs, $oper) = array("ASC", ">=");
 157                 else /* $direction == HistoryPage::DIR_NEXT */
 158                         list($dirs, $oper) = array("DESC", "<=");
 159
 160                 if( $offset )
 161                         $offsets = array("rev_timestamp $oper '$offset'");
 162                 else
 163                         $offsets = array();
 164
 165                 $page_id = $this->title->getArticleID();
 166
 167                 return $dbr->select( 'revision',
 168                         Revision::selectFields(),
 169                         array_merge(array("rev_page=$page_id"), $offsets),
 170                         __METHOD__,
 171                         array( 'ORDER BY' => "rev_timestamp $dirs",
 172                                 'USE INDEX' => 'page_timestamp', 'LIMIT' => $limit)
 173                 );
 174         }
 175
 176         /**
 177          * Output a subscription feed listing recent edits to this page.
 178          * @param string $type
 179          */
 180         function feed( $type ) {
 181                 global $wgFeedClasses, $wgRequest, $wgFeedLimit;
 182                 if( !FeedUtils::checkFeedOutput($type) ) {
 183                         return;
 184                 }
 185
 186                 $feed = new $wgFeedClasses[$type](
 187                 $this->title->getPrefixedText() . ' - ' .
 188                 wfMsgForContent( 'history-feed-title' ),
 189                 wfMsgForContent( 'history-feed-description' ),
 190                 $this->title->getFullUrl( 'action=history' ) );
 191
 192                 // Get a limit on number of feed entries. Provide a sane default
 193                 // of 10 if none is defined (but limit to $wgFeedLimit max)
 194                 $limit = $wgRequest->getInt( 'limit', 10 );
 195                 if( $limit > $wgFeedLimit || $limit < 1 ) {
 196                         $limit = 10;
 197                 }
 198                 $items = $this->fetchRevisions($limit, 0, HistoryPage::DIR_NEXT);
 199
 200                 $feed->outHeader();
 201                 if( $items ) {
 202                         foreach( $items as $row ) {
 203                                 $feed->outItem( $this->feedItem( $row ) );
 204                         }
 205                 } else {
 206                         $feed->outItem( $this->feedEmpty() );
 207                 }
 208                 $feed->outFooter();
 209         }
 210
 211         function feedEmpty() {
 212                 global $wgOut;
 213                 return new FeedItem(
 214                         wfMsgForContent( 'nohistory' ),
 215                         $wgOut->parse( wfMsgForContent( 'history-feed-empty' ) ),
 216                         $this->title->getFullUrl(),
 217                         wfTimestamp( TS_MW ),
 218                                 '',
 219                         $this->title->getTalkPage()->getFullUrl() );
 220         }
 221
 222         /**
 223          * Generate a FeedItem object from a given revision table row
 224          * Borrows Recent Changes' feed generation functions for formatting;
 225          * includes a diff to the previous revision (if any).
 226          *
 227          * @param $row
 228          * @return FeedItem
 229          */
 230         function feedItem( $row ) {
 231                 $rev = new Revision( $row );
 232                 $rev->setTitle( $this->title );
 233                 $text = FeedUtils::formatDiffRow( $this->title,
 234                 $this->title->getPreviousRevisionID( $rev->getId() ),
 235                 $rev->getId(),
 236                 $rev->getTimestamp(),
 237                 $rev->getComment() );
 238
 239                 if( $rev->getComment() == '' ) {
 240                         global $wgContLang;
 241                         $title = wfMsgForContent( 'history-feed-item-nocomment',
 242                         $rev->getUserText(),
 243                         $wgContLang->timeanddate( $rev->getTimestamp() ) );
 244                 } else {
 245                         $title = $rev->getUserText() . wfMsgForContent( 'colon-separator' ) . FeedItem::stripComment( $rev->getComment() );
 246                 }
 247
 248                 return new FeedItem(
 249                         $title,
 250                         $text,
 251                         $this->title->getFullUrl( 'diff=' . $rev->getId() . '&oldid=prev' ),
 252                         $rev->getTimestamp(),
 253                         $rev->getUserText(),
 254                         $this->title->getTalkPage()->getFullUrl() );
 255         }
 256 }
 257
 258
 259 /**
 260  * @ingroup Pager
 261  */
 262 class HistoryPager extends ReverseChronologicalPager {
 263         public $lastRow = false, $counter, $historyPage, $title;
 264         protected $oldIdChecked;
 265
 266         function __construct( $historyPage, $year='', $month='', $tagFilter = '' ) {
 267                 parent::__construct();
 268                 $this->historyPage = $historyPage;
 269                 $this->title = $this->historyPage->title;
 270                 $this->tagFilter = $tagFilter;
 271                 $this->getDateCond( $year, $month );
 272         }
 273
 274         function getQueryInfo() {
 275                 $queryInfo = array(
 276                         'tables'  => array('revision'),
 277                         'fields'  => array_merge( Revision::selectFields(), array('ts_tags') ),
 278                         'conds'   => array('rev_page' => $this->historyPage->title->getArticleID() ),
 279                         'options' => array( 'USE INDEX' => array('revision' => 'page_timestamp') ),
 280                         'join_conds' => array( 'tag_summary' => array( 'LEFT JOIN', 'ts_rev_id=rev_id' ) ),
 281                 );
 282                 ChangeTags::modifyDisplayQuery( $queryInfo['tables'],
 283                                                                                 $queryInfo['fields'],
 284                                                                                 $queryInfo['conds'],
 285                                                                                 $queryInfo['join_conds'],
 286                                                                                 $queryInfo['options'],
 287                                                                                 $this->tagFilter );
 288                 wfRunHooks( 'PageHistoryPager::getQueryInfo', array( &$this, &$queryInfo ) );
 289                 return $queryInfo;
 290         }
 291
 292         function getIndexField() {
 293                 return 'rev_timestamp';
 294         }
 295
 296         function formatRow( $row ) {
 297                 if( $this->lastRow ) {
 298                         $latest = $this->counter == 1 && $this->mIsFirst;
 299                         $firstInList = $this->counter == 1;
 300                         $s = $this->historyLine( $this->lastRow, $row, $this->counter++,
 301                                 $this->title->getNotificationTimestamp(), $latest, $firstInList );
 302                 } else {
 303                         $s = '';
 304                 }
 305                 $this->lastRow = $row;
 306                 return $s;
 307         }
 308
 309         /**
 310          * Creates begin of history list with a submit button
 311          *
 312          * @return string HTML output
 313          */
 314         function getStartBody() {
 315                 global $wgScript, $wgEnableHtmlDiff, $wgUser;
 316                 $this->lastRow = false;
 317                 $this->counter = 1;
 318                 $this->oldIdChecked = 0;
 319
 320                 $s = wfMsgExt( 'histlegend', array( 'parse') );
 321                 if( $this->getNumRows() > 1 && $wgUser->isAllowed('deleterevision') ) {
 322                         $revdel = SpecialPage::getTitleFor( 'Revisiondelete' );
 323                         $s .= Xml::openElement( 'form',
 324                                 array(
 325                                         'action' => $revdel->getLocalURL( array(
 326                                                 'type' => 'revision',
 327                                                 'target' => $this->title->getPrefixedDbKey()
 328                                         ) ),
 329                                         'method' => 'post',
 330                                         'id' => 'mw-history-revdeleteform',
 331                                         'style'  => 'visibility:hidden;float:right;'
 332                                 )
 333                         );
 334                         $s .= Xml::hidden( 'ids', '', array('id'=>'revdel-oldid') );
 335                         $s .= Xml::submitButton( wfMsg( 'showhideselectedversions' ) );
 336                         $s .= Xml::closeElement( 'form' );
 337                 }
 338                 $s .= Xml::openElement( 'form', array( 'action' => $wgScript,
 339                         'id' => 'mw-history-compare' ) );
 340                 $s .= Xml::hidden( 'title', $this->title->getPrefixedDbKey() );
 341                 if( $wgEnableHtmlDiff ) {
 342                         $s .= $this->submitButton( wfMsg( 'visualcomparison'),
 343                                 array(
 344                                         'name' => 'htmldiff',
 345                                         'class'     => 'historysubmit',
 346                                         'accesskey' => wfMsg( 'accesskey-visualcomparison' ),
 347                                         'title'     => wfMsg( 'tooltip-compareselectedversions' ),
 348                                 )
 349                         );
 350                         $s .= $this->submitButton( wfMsg( 'wikicodecomparison'),
 351                                 array(
 352                                         'class'     => 'historysubmit',
 353                                         'accesskey' => wfMsg( 'accesskey-compareselectedversions' ),
 354                                         'title'     => wfMsg( 'tooltip-compareselectedversions' ),
 355                                 )
 356                         );
 357                 } else {
 358                         $s .= $this->submitButton( wfMsg( 'compareselectedversions'),
 359                                 array(
 360                                         'class'     => 'historysubmit',
 361                                         'accesskey' => wfMsg( 'accesskey-compareselectedversions' ),
 362                                         'title'     => wfMsg( 'tooltip-compareselectedversions' ),
 363                                 )
 364                         );
 365                 }
 366                 $s .= '<ul id="pagehistory">' . "\n";
 367                 return $s;
 368         }
 369
 370         function getEndBody() {
 371
 372                 if( $this->lastRow ) {
 373                         $latest = $this->counter == 1 && $this->mIsFirst;
 374                         $firstInList = $this->counter == 1;
 375                         if( $this->mIsBackwards ) {
 376                                 # Next row is unknown, but for UI reasons, probably exists if an offset has been specified
 377                                 if( $this->mOffset == '' ) {
 378                                         $next = null;
 379                                 } else {
 380                                         $next = 'unknown';
 381                                 }
 382                         } else {
 383                                 # The next row is the past-the-end row
 384                                 $next = $this->mPastTheEndRow;
 385                         }
 386                         $s = $this->historyLine( $this->lastRow, $next, $this->counter++,
 387                                 $this->title->getNotificationTimestamp(), $latest, $firstInList );
 388                 } else {
 389                         $s = '';
 390                 }
 391
 392                 global $wgEnableHtmlDiff;
 393                 $s .= '</ul>';
 394                 if( $wgEnableHtmlDiff ) {
 395                         $s .= $this->submitButton( wfMsg( 'visualcomparison'),
 396                                 array(
 397                                         'name' => 'htmldiff',
 398                                         'class'     => 'historysubmit',
 399                                         'accesskey' => wfMsg( 'accesskey-visualcomparison' ),
 400                                         'title'     => wfMsg( 'tooltip-compareselectedversions' ),
 401                                 )
 402                         );
 403                         $s .= $this->submitButton( wfMsg( 'wikicodecomparison'),
 404                                 array(
 405                                         'class'     => 'historysubmit',
 406                                         'accesskey' => wfMsg( 'accesskey-compareselectedversions' ),
 407                                         'title'     => wfMsg( 'tooltip-compareselectedversions' ),
 408                                 )
 409                         );
 410                 } else {
 411                         $s .= $this->submitButton( wfMsg( 'compareselectedversions'),
 412                                 array(
 413                                         'class'     => 'historysubmit',
 414                                         'accesskey' => wfMsg( 'accesskey-compareselectedversions' ),
 415                                         'title'     => wfMsg( 'tooltip-compareselectedversions' ),
 416                                 )
 417                         );
 418                 }
 419                 $s .= '</form>';
 420                 return $s;
 421         }
 422
 423         /**
 424          * Creates a submit button
 425          *
 426          * @param array $attributes attributes
 427          * @return string HTML output for the submit button
 428          */
 429         function submitButton($message, $attributes = array() ) {
 430                 # Disable submit button if history has 1 revision only
 431                 if( $this->getNumRows() > 1 ) {
 432                         return Xml::submitButton( $message , $attributes );
 433                 } else {
 434                         return '';
 435                 }
 436         }
 437
 438         /**
 439          * Returns a row from the history printout.
 440          *
 441          * @todo document some more, and maybe clean up the code (some params redundant?)
 442          *
 443          * @param Row $row The database row corresponding to the previous line.
 444          * @param mixed $next The database row corresponding to the next line.
 445          * @param int $counter Apparently a counter of what row number we're at, counted from the top row = 1.
 446          * @param $notificationtimestamp
 447          * @param bool $latest Whether this row corresponds to the page's latest revision.
 448          * @param bool $firstInList Whether this row corresponds to the first displayed on this history page.
 449          * @return string HTML output for the row
 450          */
 451         function historyLine( $row, $next, $counter = '', $notificationtimestamp = false,
 452                 $latest = false, $firstInList = false )
 453         {
 454                 global $wgUser, $wgLang;
 455                 $rev = new Revision( $row );
 456                 $rev->setTitle( $this->title );
 457
 458                 $curlink = $this->curLink( $rev, $latest );
 459                 $lastlink = $this->lastLink( $rev, $next, $counter );
 460                 $diffButtons = $this->diffButtons( $rev, $firstInList, $counter );
 461                 $link = $this->revLink( $rev );
 462                 $classes = array();
 463
 464                 $s = "($curlink) ($lastlink) $diffButtons";
 465
 466                 if( $wgUser->isAllowed( 'deleterevision' ) ) {
 467                         // Hide JS by default for non-JS browsing
 468                         $hidden = array( 'style' => 'display:none' );
 469                         // If revision was hidden from sysops
 470                         if( !$rev->userCan( Revision::DELETED_RESTRICTED ) ) {
 471                                 $del = Xml::check( 'deleterevisions', false,
 472                                         $hidden + array('disabled' => 'disabled') );
 473                                 $del .= Xml::tags( 'span', array( 'class'=>'mw-revdelundel-link' ),
 474                                         '(' . $this->historyPage->message['rev-delundel'] . ')' );
 475                         // Otherwise, show the link...
 476                         } else {
 477                                 $id = $rev->getId();
 478                                 $jsCall = "updateShowHideForm($id,this.checked)";
 479                                 $del = Xml::check( 'showhiderevisions', false,
 480                                         $hidden + array(
 481                                                 'onchange' => $jsCall,
 482                                                 'id' => "mw-revdel-$id" ) );
 483                                 $query = array(
 484                                         'type' => 'revision',
 485                                         'target' => $this->title->getPrefixedDbkey(),
 486                                         'ids' => $rev->getId() );
 487                                 $del .= $this->getSkin()->revDeleteLink( $query,
 488                                         $rev->isDeleted( Revision::DELETED_RESTRICTED ) );
 489                         }
 490                         $s .= " $del ";
 491                 }
 492
 493                 $s .= " $link";
 494                 $s .= " <span class='history-user'>" . $this->getSkin()->revUserTools( $rev, true ) . "</span>";
 495
 496                 if( $rev->isMinor() ) {
 497                         $s .= ' ' . ChangesList::flag( 'minor' );
 498                 }
 499
 500                 if( !is_null( $size = $rev->getSize() ) && !$rev->isDeleted( Revision::DELETED_TEXT ) ) {
 501                         $s .= ' ' . $this->getSkin()->formatRevisionSize( $size );
 502                 }
 503
 504                 $s .= $this->getSkin()->revComment( $rev, false, true );
 505
 506                 if( $notificationtimestamp && ($row->rev_timestamp >= $notificationtimestamp) ) {
 507                         $s .= ' <span class="updatedmarker">' .  wfMsgHtml( 'updatedmarker' ) . '</span>';
 508                 }
 509
 510                 $tools = array();
 511
 512                 if( !is_null( $next ) && is_object( $next ) ) {
 513                         if( $latest && $this->title->userCan( 'rollback' ) && $this->title->userCan( 'edit' ) ) {
 514                                 $tools[] = '<span class="mw-rollback-link">'.
 515                                         $this->getSkin()->buildRollbackLink( $rev ).'</span>';
 516                         }
 517
 518                         if( $this->title->quickUserCan( 'edit' )
 519                                 && !$rev->isDeleted( Revision::DELETED_TEXT )
 520                                 && !$next->rev_deleted & Revision::DELETED_TEXT )
 521                         {
 522                                 # Create undo tooltip for the first (=latest) line only
 523                                 $undoTooltip = $latest
 524                                         ? array( 'title' => wfMsg( 'tooltip-undo' ) )
 525                                         : array();
 526                                 $undolink = $this->getSkin()->link(
 527                                         $this->title,
 528                                         wfMsgHtml( 'editundo' ),
 529                                         $undoTooltip,
 530                                         array( 'action' => 'edit', 'undoafter' => $next->rev_id, 'undo' => $rev->getId() ),
 531                                         array( 'known', 'noclasses' )
 532                                 );
 533                                 $tools[] = "<span class=\"mw-history-undo\">{$undolink}</span>";
 534                         }
 535                 }
 536
 537                 if( $tools ) {
 538                         $s .= ' (' . $wgLang->pipeList( $tools ) . ')';
 539                 }
 540
 541                 # Tags
 542                 list($tagSummary, $newClasses) = ChangeTags::formatSummaryRow( $row->ts_tags, 'history' );
 543                 $classes = array_merge( $classes, $newClasses );
 544                 $s .= " $tagSummary";
 545
 546                 wfRunHooks( 'PageHistoryLineEnding', array( $this, &$row , &$s ) );
 547
 548                 $attribs = array();
 549                 if ( $classes ) {
 550                         $attribs['class'] = implode( ' ', $classes );
 551                 }
 552
 553                 return Xml::tags( 'li', $attribs, $s ) . "\n";
 554         }
 555
 556         /**
 557          * Create a link to view this revision of the page
 558          * @param Revision $rev
 559          * @returns string
 560          */
 561         function revLink( $rev ) {
 562                 global $wgLang;
 563                 $date = $wgLang->timeanddate( wfTimestamp(TS_MW, $rev->getTimestamp()), true );
 564                 $date = htmlspecialchars( $date );
 565                 if( !$rev->isDeleted( Revision::DELETED_TEXT ) ) {
 566                         $link = $this->getSkin()->link(
 567                                 $this->title,
 568                                 $date,
 569                                 array(),
 570                                 array( 'oldid' => $rev->getId() ),
 571                                 array( 'known', 'noclasses' )
 572                         );
 573                 } else {
 574                         $link = "<span class=\"history-deleted\">$date</span>";
 575                 }
 576                 return $link;
 577         }
 578
 579         /**
 580          * Create a diff-to-current link for this revision for this page
 581          * @param Revision $rev
 582          * @param Bool $latest, this is the latest revision of the page?
 583          * @returns string
 584          */
 585         function curLink( $rev, $latest ) {
 586                 $cur = $this->historyPage->message['cur'];
 587                 if( $latest || !$rev->userCan( Revision::DELETED_TEXT ) ) {
 588                         return $cur;
 589                 } else {
 590                         return $this->getSkin()->link(
 591                                 $this->title,
 592                                 $cur,
 593                                 array(),
 594                                 array(
 595                                         'diff' => $this->title->getLatestRevID(),
 596                                         'oldid' => $rev->getId()
 597                                 ),
 598                                 array( 'known', 'noclasses' )
 599                         );
 600                 }
 601         }
 602
 603         /**
 604          * Create a diff-to-previous link for this revision for this page.
 605          * @param Revision $prevRev, the previous revision
 606          * @param mixed $next, the newer revision
 607          * @param int $counter, what row on the history list this is
 608          * @returns string
 609          */
 610         function lastLink( $prevRev, $next, $counter ) {
 611                 $last = $this->historyPage->message['last'];
 612                 # $next may either be a Row, null, or "unkown"
 613                 $nextRev = is_object($next) ? new Revision( $next ) : $next;
 614                 if( is_null($next) ) {
 615                         # Probably no next row
 616                         return $last;
 617                 } elseif( $next === 'unknown' ) {
 618                         # Next row probably exists but is unknown, use an oldid=prev link
 619                         return $this->getSkin()->link(
 620                                 $this->title,
 621                                 $last,
 622                                 array(),
 623                                 array(
 624                                         'diff' => $prevRev->getId(),
 625                                         'oldid' => 'prev'
 626                                 ),
 627                                 array( 'known', 'noclasses' )
 628                         );
 629                 } elseif( !$prevRev->userCan(Revision::DELETED_TEXT) || !$nextRev->userCan(Revision::DELETED_TEXT) ) {
 630                         return $last;
 631                 } else {
 632                         return $this->getSkin()->link(
 633                                 $this->title,
 634                                 $last,
 635                                 array(),
 636                                 array(
 637                                         'diff' => $prevRev->getId(),
 638                                         'oldid' => $next->rev_id
 639                                 ),
 640                                 array( 'known', 'noclasses' )
 641                         );
 642                 }
 643         }
 644
 645         /**
 646          * Create radio buttons for page history
 647          *
 648          * @param object $rev Revision
 649          * @param bool $firstInList Is this version the first one?
 650          * @param int $counter A counter of what row number we're at, counted from the top row = 1.
 651          * @return string HTML output for the radio buttons
 652          */
 653         function diffButtons( $rev, $firstInList, $counter ) {
 654                 if( $this->getNumRows() > 1 ) {
 655                         $id = $rev->getId();
 656                         $radio = array( 'type'  => 'radio', 'value' => $id );
 657                         /** @todo: move title texts to javascript */
 658                         if( $firstInList ) {
 659                                 $first = Xml::element( 'input',
 660                                         array_merge( $radio, array(
 661                                                 'style' => 'visibility:hidden',
 662                                                 'name'  => 'oldid',
 663                                                 'id' => 'mw-oldid-null' ) )
 664                                 );
 665                                 $checkmark = array( 'checked' => 'checked' );
 666                         } else {
 667                                 # Check visibility of old revisions
 668                                 if( !$rev->userCan( Revision::DELETED_TEXT ) ) {
 669                                         $radio['disabled'] = 'disabled';
 670                                         $checkmark = array(); // We will check the next possible one
 671                                 } else if( $counter == 2 || !$this->oldIdChecked ) {
 672                                         $checkmark = array( 'checked' => 'checked' );
 673                                         $this->oldIdChecked = $id;
 674                                 } else {
 675                                         $checkmark = array();
 676                                 }
 677                                 $first = Xml::element( 'input',
 678                                         array_merge( $radio, $checkmark, array(
 679                                                 'name'  => 'oldid',
 680                                                 'id' => "mw-oldid-$id" ) ) );
 681                                 $checkmark = array();
 682                         }
 683                         $second = Xml::element( 'input',
 684                                 array_merge( $radio, $checkmark, array(
 685                                         'name'  => 'diff',
 686                                         'id' => "mw-diff-$id" ) ) );
 687                         return $first . $second;
 688                 } else {
 689                         return '';
 690                 }
 691         }
 692 }
 693
 694 /**
 695  * Backwards-compatibility aliases
 696  */
 697 class PageHistory extends HistoryPage {}
 698 class PageHistoryPager extends HistoryPager {}
 699