includes/diff/DifferenceEngine.php

   1 <?php
   2 /**
   3  * User interface for the difference engine.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup DifferenceEngine
  22  */
  23
  24 /**
  25  * Constant to indicate diff cache compatibility.
  26  * Bump this when changing the diff formatting in a way that
  27  * fixes important bugs or such to force cached diff views to
  28  * clear.
  29  */
  30 define( 'MW_DIFF_VERSION', '1.11a' );
  31
  32 /**
  33  * @todo document
  34  * @ingroup DifferenceEngine
  35  */
  36 class DifferenceEngine extends ContextSource {
  37         /**#@+
  38          * @private
  39          */
  40         var $mOldid, $mNewid;
  41         var $mOldContent, $mNewContent;
  42         protected $mDiffLang;
  43
  44         /**
  45          * @var Title
  46          */
  47         var $mOldPage, $mNewPage;
  48         var $mRcidMarkPatrolled;
  49
  50         /**
  51          * @var Revision
  52          */
  53         var $mOldRev, $mNewRev;
  54         private $mRevisionsIdsLoaded = false; // Have the revisions IDs been loaded
  55         var $mRevisionsLoaded = false; // Have the revisions been loaded
  56         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  57         var $mCacheHit = false; // Was the diff fetched from cache?
  58
  59         /**
  60          * Set this to true to add debug info to the HTML output.
  61          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  62          * (bug 20601)
  63          */
  64         var $enableDebugComment = false;
  65
  66         // If true, line X is not displayed when X is 1, for example to increase
  67         // readability and conserve space with many small diffs.
  68         protected $mReducedLineNumbers = false;
  69
  70         // Link to action=markpatrolled
  71         protected $mMarkPatrolledLink = null;
  72
  73         protected $unhide = false; # show rev_deleted content if allowed
  74         /**#@-*/
  75
  76         /**
  77          * Constructor
  78          * @param $context IContextSource context to use, anything else will be ignored
  79          * @param $old Integer old ID we want to show and diff with.
  80          * @param $new String either 'prev' or 'next'.
  81          * @param $rcid Integer ??? FIXME (default 0)
  82          * @param $refreshCache boolean If set, refreshes the diff cache
  83          * @param $unhide boolean If set, allow viewing deleted revs
  84          */
  85         function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
  86                 $refreshCache = false, $unhide = false )
  87         {
  88                 if ( $context instanceof IContextSource ) {
  89                         $this->setContext( $context );
  90                 }
  91
  92                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
  93
  94                 $this->mOldid = $old;
  95                 $this->mNewid = $new;
  96                 $this->mRcidMarkPatrolled = intval( $rcid );  # force it to be an integer
  97                 $this->mRefreshCache = $refreshCache;
  98                 $this->unhide = $unhide;
  99         }
 100
 101         /**
 102          * @param $value bool
 103          */
 104         function setReducedLineNumbers( $value = true ) {
 105                 $this->mReducedLineNumbers = $value;
 106         }
 107
 108         /**
 109          * @return Language
 110          */
 111         function getDiffLang() {
 112                 if ( $this->mDiffLang === null ) {
 113                         # Default language in which the diff text is written.
 114                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 115                 }
 116                 return $this->mDiffLang;
 117         }
 118
 119         /**
 120          * @return bool
 121          */
 122         function wasCacheHit() {
 123                 return $this->mCacheHit;
 124         }
 125
 126         /**
 127          * @return int
 128          */
 129         function getOldid() {
 130                 $this->loadRevisionIds();
 131                 return $this->mOldid;
 132         }
 133
 134         /**
 135          * @return Bool|int
 136          */
 137         function getNewid() {
 138                 $this->loadRevisionIds();
 139                 return $this->mNewid;
 140         }
 141
 142         /**
 143          * Look up a special:Undelete link to the given deleted revision id,
 144          * as a workaround for being unable to load deleted diffs in currently.
 145          *
 146          * @param int $id revision ID
 147          * @return mixed URL or false
 148          */
 149         function deletedLink( $id ) {
 150                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 151                         $dbr = wfGetDB( DB_SLAVE );
 152                         $row = $dbr->selectRow('archive', '*',
 153                                 array( 'ar_rev_id' => $id ),
 154                                 __METHOD__ );
 155                         if ( $row ) {
 156                                 $rev = Revision::newFromArchiveRow( $row );
 157                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 158                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
 159                                         'target' => $title->getPrefixedText(),
 160                                         'timestamp' => $rev->getTimestamp()
 161                                 ));
 162                         }
 163                 }
 164                 return false;
 165         }
 166
 167         /**
 168          * Build a wikitext link toward a deleted revision, if viewable.
 169          *
 170          * @param int $id revision ID
 171          * @return string wikitext fragment
 172          */
 173         function deletedIdMarker( $id ) {
 174                 $link = $this->deletedLink( $id );
 175                 if ( $link ) {
 176                         return "[$link $id]";
 177                 } else {
 178                         return $id;
 179                 }
 180         }
 181
 182         function showDiffPage( $diffOnly = false ) {
 183                 wfProfileIn( __METHOD__ );
 184
 185                 # Allow frames except in certain special cases
 186                 $out = $this->getOutput();
 187                 $out->allowClickjacking();
 188                 $out->setRobotPolicy( 'noindex,nofollow' );
 189
 190                 if ( !$this->loadRevisionData() ) {
 191                         // Sounds like a deleted revision... Let's see what we can do.
 192                         $t = $this->getTitle()->getPrefixedText();
 193                         $d = $this->msg( 'missingarticle-diff',
 194                                 $this->deletedIdMarker( $this->mOldid ),
 195                                 $this->deletedIdMarker( $this->mNewid ) )->escaped();
 196                         $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 197                         $out->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", "<span class='plainlinks'>$d</span>" );
 198                         wfProfileOut( __METHOD__ );
 199                         return;
 200                 }
 201
 202                 $user = $this->getUser();
 203                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 204                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 205                         $permErrors = wfMergeErrorArrays( $permErrors,
 206                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 207                 }
 208                 if ( count( $permErrors ) ) {
 209                         wfProfileOut( __METHOD__ );
 210                         throw new PermissionsError( 'read', $permErrors );
 211                 }
 212
 213                 # If external diffs are enabled both globally and for the user,
 214                 # we'll use the application/x-external-editor interface to call
 215                 # an external diff tool like kompare, kdiff3, etc.
 216                 if ( ExternalEdit::useExternalEngine( $this->getContext(), 'diff' ) ) {
 217                         $urls = array(
 218                                 'File' => array( 'Extension' => 'wiki', 'URL' =>
 219                                         # This should be mOldPage, but it may not be set, see below.
 220                                         $this->mNewPage->getCanonicalURL( array(
 221                                                 'action' => 'raw', 'oldid' => $this->mOldid ) )
 222                                 ),
 223                                 'File2' => array( 'Extension' => 'wiki', 'URL' =>
 224                                         $this->mNewPage->getCanonicalURL( array(
 225                                                 'action' => 'raw', 'oldid' => $this->mNewid ) )
 226                                 ),
 227                         );
 228
 229                         $externalEditor = new ExternalEdit( $this->getContext(), $urls );
 230                         $externalEditor->execute();
 231
 232                         wfProfileOut( __METHOD__ );
 233                         return;
 234                 }
 235
 236                 $rollback = '';
 237                 $undoLink = '';
 238
 239                 $query = array();
 240                 # Carry over 'diffonly' param via navigation links
 241                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 242                         $query['diffonly'] = $diffOnly;
 243                 }
 244                 # Cascade unhide param in links for easy deletion browsing
 245                 if ( $this->unhide ) {
 246                         $query['unhide'] = 1;
 247                 }
 248
 249                 # Check if one of the revisions is deleted/suppressed
 250                 $deleted = $suppressed = false;
 251                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 252
 253                 # mOldRev is false if the difference engine is called with a "vague" query for
 254                 # a diff between a version V and its previous version V' AND the version V
 255                 # is the first version of that article. In that case, V' does not exist.
 256                 if ( $this->mOldRev === false ) {
 257                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 258                         $samePage = true;
 259                         $oldHeader = '';
 260                 } else {
 261                         wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 262
 263                         $sk = $this->getSkin();
 264                         if ( method_exists( $sk, 'suppressQuickbar' ) ) {
 265                                 $sk->suppressQuickbar();
 266                         }
 267
 268                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 269                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 270                                 $samePage = true;
 271                         } else {
 272                                 $out->setPageTitle( $this->msg( 'difference-title-multipage', $this->mOldPage->getPrefixedText(),
 273                                         $this->mNewPage->getPrefixedText() ) );
 274                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 275                                 $samePage = false;
 276                         }
 277
 278                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 279                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 280                                         $out->preventClickjacking();
 281                                         $rollback = '&#160;&#160;&#160;' . Linker::generateRollback( $this->mNewRev );
 282                                 }
 283                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 284                                         $undoLink = ' ' . $this->msg( 'parentheses' )->rawParams(
 285                                                 Html::element( 'a', array(
 286                                                         'href' => $this->mNewPage->getLocalUrl( array(
 287                                                                 'action' => 'edit',
 288                                                                 'undoafter' => $this->mOldid,
 289                                                                 'undo' => $this->mNewid ) ),
 290                                                         'title' => Linker::titleAttrib( 'undo' )
 291                                                 ),
 292                                                 $this->msg( 'editundo' )->text()
 293                                         ) )->escaped();
 294                                 }
 295                         }
 296
 297                         # Make "previous revision link"
 298                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 299                                 $prevlink = Linker::linkKnown(
 300                                         $this->mOldPage,
 301                                         $this->msg( 'previousdiff' )->escaped(),
 302                                         array( 'id' => 'differences-prevlink' ),
 303                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 304                                 );
 305                         } else {
 306                                 $prevlink = '&#160;';
 307                         }
 308
 309                         if ( $this->mOldRev->isMinor() ) {
 310                                 $oldminor = ChangesList::flag( 'minor' );
 311                         } else {
 312                                 $oldminor = '';
 313                         }
 314
 315                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 316                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 317
 318                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 319                                 '<div id="mw-diff-otitle2">' .
 320                                         Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 321                                 '<div id="mw-diff-otitle3">' . $oldminor .
 322                                         Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 323                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 324
 325                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 326                                 $deleted = true; // old revisions text is hidden
 327                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 328                                         $suppressed = true; // also suppressed
 329                                 }
 330                         }
 331
 332                         # Check if this user can see the revisions
 333                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 334                                 $allowed = false;
 335                         }
 336                 }
 337
 338                 # Make "next revision link"
 339                 # Skip next link on the top revision
 340                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 341                         $nextlink = Linker::linkKnown(
 342                                 $this->mNewPage,
 343                                 $this->msg( 'nextdiff' )->escaped(),
 344                                 array( 'id' => 'differences-nextlink' ),
 345                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 346                         );
 347                 } else {
 348                         $nextlink = '&#160;';
 349                 }
 350
 351                 if ( $this->mNewRev->isMinor() ) {
 352                         $newminor = ChangesList::flag( 'minor' );
 353                 } else {
 354                         $newminor = '';
 355                 }
 356
 357                 # Handle RevisionDelete links...
 358                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 359                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) . $undoLink;
 360
 361                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 362                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 363                                 " $rollback</div>" .
 364                         '<div id="mw-diff-ntitle3">' . $newminor .
 365                                 Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 366                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 367
 368                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 369                         $deleted = true; // new revisions text is hidden
 370                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) )
 371                                 $suppressed = true; // also suppressed
 372                 }
 373
 374                 # If the diff cannot be shown due to a deleted revision, then output
 375                 # the diff header and links to unhide (if available)...
 376                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 377                         $this->showDiffStyle();
 378                         $multi = $this->getMultiNotice();
 379                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 380                         if ( !$allowed ) {
 381                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 382                                 # Give explanation for why revision is not visible
 383                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 384                                         array( $msg ) );
 385                         } else {
 386                                 # Give explanation and add a link to view the diff...
 387                                 $link = $this->getTitle()->getFullUrl( $this->getRequest()->appendQueryValue( 'unhide', '1', true ) );
 388                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 389                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
 390                         }
 391                 # Otherwise, output a regular diff...
 392                 } else {
 393                         # Add deletion notice if the user is viewing deleted content
 394                         $notice = '';
 395                         if ( $deleted ) {
 396                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 397                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" . $this->msg( $msg )->parse() . "</div>\n";
 398                         }
 399                         $this->showDiff( $oldHeader, $newHeader, $notice );
 400                         if ( !$diffOnly ) {
 401                                 $this->renderNewRevision();
 402                         }
 403                 }
 404                 wfProfileOut( __METHOD__ );
 405         }
 406
 407         /**
 408          * Get a link to mark the change as patrolled, or '' if there's either no
 409          * revision to patrol or the user is not allowed to to it.
 410          * Side effect: this method will call OutputPage::preventClickjacking()
 411          * when a link is builded.
 412          *
 413          * @return String
 414          */
 415         protected function markPatrolledLink() {
 416                 global $wgUseRCPatrol;
 417
 418                 if ( $this->mMarkPatrolledLink === null ) {
 419                         // Prepare a change patrol link, if applicable
 420                         if ( $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $this->getUser() ) ) {
 421                                 // If we've been given an explicit change identifier, use it; saves time
 422                                 if ( $this->mRcidMarkPatrolled ) {
 423                                         $rcid = $this->mRcidMarkPatrolled;
 424                                         $rc = RecentChange::newFromId( $rcid );
 425                                         // Already patrolled?
 426                                         $rcid = is_object( $rc ) && !$rc->getAttribute( 'rc_patrolled' ) ? $rcid : 0;
 427                                 } else {
 428                                         // Look for an unpatrolled change corresponding to this diff
 429                                         $db = wfGetDB( DB_SLAVE );
 430                                         $change = RecentChange::newFromConds(
 431                                                 array(
 432                                                 // Redundant user,timestamp condition so we can use the existing index
 433                                                         'rc_user_text'  => $this->mNewRev->getRawUserText(),
 434                                                         'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
 435                                                         'rc_this_oldid' => $this->mNewid,
 436                                                         'rc_last_oldid' => $this->mOldid,
 437                                                         'rc_patrolled'  => 0
 438                                                 ),
 439                                                 __METHOD__
 440                                         );
 441                                         if ( $change instanceof RecentChange ) {
 442                                                 $rcid = $change->mAttribs['rc_id'];
 443                                                 $this->mRcidMarkPatrolled = $rcid;
 444                                         } else {
 445                                                 // None found
 446                                                 $rcid = 0;
 447                                         }
 448                                 }
 449                                 // Build the link
 450                                 if ( $rcid ) {
 451                                         $this->getOutput()->preventClickjacking();
 452                                         $token = $this->getUser()->getEditToken( $rcid );
 453                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 454                                                 $this->mNewPage,
 455                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 456                                                 array(),
 457                                                 array(
 458                                                         'action' => 'markpatrolled',
 459                                                         'rcid' => $rcid,
 460                                                         'token' => $token,
 461                                                 )
 462                                         ) . ']</span>';
 463                                 } else {
 464                                         $this->mMarkPatrolledLink = '';
 465                                 }
 466                         } else {
 467                                 $this->mMarkPatrolledLink = '';
 468                         }
 469                 }
 470
 471                 return $this->mMarkPatrolledLink;
 472         }
 473
 474         /**
 475          * @param $rev Revision
 476          * @return String
 477          */
 478         protected function revisionDeleteLink( $rev ) {
 479                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 480                 if ( $link !== '' ) {
 481                         $link = '&#160;&#160;&#160;' . $link . ' ';
 482                 }
 483                 return $link;
 484         }
 485
 486         /**
 487          * Show the new revision of the page.
 488          */
 489         function renderNewRevision() {
 490                 wfProfileIn( __METHOD__ );
 491                 $out = $this->getOutput();
 492                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 493                 # Add "current version as of X" title
 494                 $out->addHTML( "<hr class='diff-hr' />
 495                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 496                 # Page content may be handled by a hooked call instead...
 497                 if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 498                         $this->loadNewText();
 499                         $out->setRevisionId( $this->mNewid );
 500                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 501                         $out->setArticleFlag( true );
 502
 503                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) { #NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 504                                 // Stolen from Article::view --AG 2007-10-11
 505                                 // Give hooks a chance to customise the output
 506                                 // @TODO: standardize this crap into one function
 507                                 if ( !Hook::isRegistered( 'ShowRawCssJs' )
 508                     || wfRunHooks( 'ShowRawCssJs', array( ContentHandler::getContentText( $this->mNewContent ), $this->mNewPage, $out ) ) ) { #NOTE: deperecated hook, B/C only
 509                     // use the content object's own rendering
 510                     $po = $this->mContentObject->getParserOutput();
 511                     $out->addHTML( $po->getText() );
 512                                 }
 513             } elseif( !wfRunHooks( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 514                 // Handled by extension
 515             } elseif( Hooks::isRegistered( 'ArticleViewCustom' )
 516                     && !wfRunHooks( 'ArticleViewCustom', array( ContentHandler::getContentText( $this->mNewContent ), $this->mNewPage, $out ) ) ) { #NOTE: deperecated hook, B/C only
 517                 // Handled by extension
 518                         } else {
 519                                 // Normal page
 520                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 521                                         // If the Title stored in the context is the same as the one
 522                                         // of the new revision, we can use its associated WikiPage
 523                                         // object.
 524                                         $wikiPage = $this->getWikiPage();
 525                                 } else {
 526                                         // Otherwise we need to create our own WikiPage object
 527                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 528                                 }
 529
 530                                 $parserOptions = ParserOptions::newFromContext( $this->getContext() );
 531                                 $parserOptions->enableLimitReport();
 532                                 $parserOptions->setTidy( true );
 533
 534                                 if ( !$this->mNewRev->isCurrent() ) {
 535                                         $parserOptions->setEditSection( false );
 536                                 }
 537
 538                                 $parserOutput = $wikiPage->getParserOutput( $parserOptions, $this->mNewid );
 539
 540                                 # WikiPage::getParserOutput() should not return false, but just in case
 541                                 if( $parserOutput ) {
 542                                         $out->addParserOutput( $parserOutput );
 543                                 }
 544                         }
 545                 }
 546                 # Add redundant patrol link on bottom...
 547                 $out->addHTML( $this->markPatrolledLink() );
 548
 549                 wfProfileOut( __METHOD__ );
 550         }
 551
 552         /**
 553          * Get the diff text, send it to the OutputPage object
 554          * Returns false if the diff could not be generated, otherwise returns true
 555          *
 556          * @return bool
 557          */
 558         function showDiff( $otitle, $ntitle, $notice = '' ) {
 559                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 560                 if ( $diff === false ) {
 561                         $this->getOutput()->addWikiMsg( 'missing-article', "<nowiki>(fixme, bug)</nowiki>", '' );
 562                         return false;
 563                 } else {
 564                         $this->showDiffStyle();
 565                         $this->getOutput()->addHTML( $diff );
 566                         return true;
 567                 }
 568         }
 569
 570         /**
 571          * Add style sheets and supporting JS for diff display.
 572          */
 573         function showDiffStyle() {
 574                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 575         }
 576
 577         /**
 578          * Get complete diff table, including header
 579          *
 580          * @param $otitle Title: old title
 581          * @param $ntitle Title: new title
 582          * @param $notice String: HTML between diff header and body
 583          * @return mixed
 584          */
 585         function getDiff( $otitle, $ntitle, $notice = '' ) {
 586                 $body = $this->getDiffBody();
 587                 if ( $body === false ) {
 588                         return false;
 589                 } else {
 590                         $multi = $this->getMultiNotice();
 591                         return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 592                 }
 593         }
 594
 595         /**
 596          * Get the diff table body, without header
 597          *
 598          * @return mixed (string/false)
 599          */
 600         public function getDiffBody() {
 601                 global $wgMemc;
 602                 wfProfileIn( __METHOD__ );
 603                 $this->mCacheHit = true;
 604                 // Check if the diff should be hidden from this user
 605                 if ( !$this->loadRevisionData() ) {
 606                         wfProfileOut( __METHOD__ );
 607                         return false;
 608                 } elseif ( $this->mOldRev && !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 609                         wfProfileOut( __METHOD__ );
 610                         return false;
 611                 } elseif ( $this->mNewRev && !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 612                         wfProfileOut( __METHOD__ );
 613                         return false;
 614                 }
 615                 // Short-circuit
 616                 // If mOldRev is false, it means that the
 617                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 618                         && $this->mOldRev->getID() == $this->mNewRev->getID() ) )
 619                 {
 620                         wfProfileOut( __METHOD__ );
 621                         return '';
 622                 }
 623                 // Cacheable?
 624                 $key = false;
 625                 if ( $this->mOldid && $this->mNewid ) {
 626                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 627                                 'oldid', $this->mOldid, 'newid', $this->mNewid );
 628                         // Try cache
 629                         if ( !$this->mRefreshCache ) {
 630                                 $difftext = $wgMemc->get( $key );
 631                                 if ( $difftext ) {
 632                                         wfIncrStats( 'diff_cache_hit' );
 633                                         $difftext = $this->localiseLineNumbers( $difftext );
 634                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 635                                         wfProfileOut( __METHOD__ );
 636                                         return $difftext;
 637                                 }
 638                         } // don't try to load but save the result
 639                 }
 640                 $this->mCacheHit = false;
 641
 642                 // Loadtext is permission safe, this just clears out the diff
 643                 if ( !$this->loadText() ) {
 644                         wfProfileOut( __METHOD__ );
 645                         return false;
 646                 }
 647
 648         #TODO: make sure both Content objects have the same content model. What do we do if they don't?
 649
 650                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 651
 652                 // Save to cache for 7 days
 653                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 654                         wfIncrStats( 'diff_uncacheable' );
 655                 } elseif ( $key !== false && $difftext !== false ) {
 656                         wfIncrStats( 'diff_cache_miss' );
 657                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 658                 } else {
 659                         wfIncrStats( 'diff_uncacheable' );
 660                 }
 661                 // Replace line numbers with the text in the user's language
 662                 if ( $difftext !== false ) {
 663                         $difftext = $this->localiseLineNumbers( $difftext );
 664                 }
 665                 wfProfileOut( __METHOD__ );
 666                 return $difftext;
 667         }
 668
 669         /**
 670          * Make sure the proper modules are loaded before we try to
 671          * make the diff
 672          */
 673         private function initDiffEngines() {
 674                 global $wgExternalDiffEngine;
 675                 if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 676                         wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
 677                         wfDl( 'php_wikidiff' );
 678                         wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 679                 }
 680                 elseif ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 681                         wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
 682                         wfDl( 'wikidiff2' );
 683                         wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 684                 }
 685         }
 686
 687     /**
 688      * Generate a diff, no caching.
 689      *
 690      * Subclasses may override this to provide a
 691      *
 692      * @param $old Content: old content
 693      * @param $new Content: new content
 694      *
 695      * @since 1.WD
 696      */
 697     function generateContentDiffBody( Content $old, Content $new ) {
 698         #XXX: generate a warning if $old or $new are not instances of TextContent?
 699         #XXX: fail if $old and $new don't have the same content model? or what?
 700
 701         $otext = $old->serialize();
 702         $ntext = $new->serialize();
 703
 704         #XXX: text should be "already segmented". what does that mean?
 705         return $this->generateTextDiffBody( $otext, $ntext );
 706     }
 707
 708     /**
 709      * Generate a diff, no caching
 710      *
 711      * @param $otext String: old text, must be already segmented
 712      * @param $ntext String: new text, must be already segmented
 713      * @deprecated since 1.WD, use generateContentDiffBody() instead!
 714      */
 715     function generateDiffBody( $otext, $ntext ) {
 716         wfDeprecated( __METHOD__, "1.WD" );
 717
 718         return $this->generateTextDiffBody( $otext, $ntext );
 719     }
 720
 721         /**
 722          * Generate a diff, no caching
 723          *
 724      * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 725      *
 726          * @param $otext String: old text, must be already segmented
 727          * @param $ntext String: new text, must be already segmented
 728          * @return bool|string
 729          */
 730         function generateTextDiffBody( $otext, $ntext ) {
 731                 global $wgExternalDiffEngine, $wgContLang;
 732
 733                 wfProfileIn( __METHOD__ );
 734
 735                 $otext = str_replace( "\r\n", "\n", $otext );
 736                 $ntext = str_replace( "\r\n", "\n", $ntext );
 737
 738                 $this->initDiffEngines();
 739
 740                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 741                         # For historical reasons, external diff engine expects
 742                         # input text to be HTML-escaped already
 743                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 744                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 745                         wfProfileOut( __METHOD__ );
 746                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 747                         $this->debug( 'wikidiff1' );
 748                 }
 749
 750                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 751                         # Better external diff engine, the 2 may some day be dropped
 752                         # This one does the escaping and segmenting itself
 753                         wfProfileIn( 'wikidiff2_do_diff' );
 754                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 755                         $text .= $this->debug( 'wikidiff2' );
 756                         wfProfileOut( 'wikidiff2_do_diff' );
 757                         wfProfileOut( __METHOD__ );
 758                         return $text;
 759                 }
 760                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 761                         # Diff via the shell
 762                         global $wgTmpDirectory;
 763                         $tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
 764                         $tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
 765
 766                         $tempFile1 = fopen( $tempName1, "w" );
 767                         if ( !$tempFile1 ) {
 768                                 wfProfileOut( __METHOD__ );
 769                                 return false;
 770                         }
 771                         $tempFile2 = fopen( $tempName2, "w" );
 772                         if ( !$tempFile2 ) {
 773                                 wfProfileOut( __METHOD__ );
 774                                 return false;
 775                         }
 776                         fwrite( $tempFile1, $otext );
 777                         fwrite( $tempFile2, $ntext );
 778                         fclose( $tempFile1 );
 779                         fclose( $tempFile2 );
 780                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 781                         wfProfileIn( __METHOD__ . "-shellexec" );
 782                         $difftext = wfShellExec( $cmd );
 783                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 784                         wfProfileOut( __METHOD__ . "-shellexec" );
 785                         unlink( $tempName1 );
 786                         unlink( $tempName2 );
 787                         wfProfileOut( __METHOD__ );
 788                         return $difftext;
 789                 }
 790
 791                 # Native PHP diff
 792                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 793                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 794                 $diffs = new Diff( $ota, $nta );
 795                 $formatter = new TableDiffFormatter();
 796                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 797                 wfProfileOut( __METHOD__ );
 798                 return $difftext;
 799         }
 800
 801         /**
 802          * Generate a debug comment indicating diff generating time,
 803          * server node, and generator backend.
 804          * @return string
 805          */
 806         protected function debug( $generator = "internal" ) {
 807                 global $wgShowHostnames;
 808                 if ( !$this->enableDebugComment ) {
 809                         return '';
 810                 }
 811                 $data = array( $generator );
 812                 if ( $wgShowHostnames ) {
 813                         $data[] = wfHostname();
 814                 }
 815                 $data[] = wfTimestamp( TS_DB );
 816                 return "<!-- diff generator: " .
 817                 implode( " ",
 818                 array_map(
 819                                         "htmlspecialchars",
 820                 $data ) ) .
 821                         " -->\n";
 822         }
 823
 824         /**
 825          * Replace line numbers with the text in the user's language
 826          * @return mixed
 827          */
 828         function localiseLineNumbers( $text ) {
 829                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 830                 array( &$this, 'localiseLineNumbersCb' ), $text );
 831         }
 832
 833         function localiseLineNumbersCb( $matches ) {
 834                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
 835                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 836         }
 837
 838
 839         /**
 840          * If there are revisions between the ones being compared, return a note saying so.
 841          * @return string
 842          */
 843         function getMultiNotice() {
 844                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 845                         return '';
 846                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 847                         // Comparing two different pages? Count would be meaningless.
 848                         return '';
 849                 }
 850
 851                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 852                         $oldRev = $this->mNewRev; // flip
 853                         $newRev = $this->mOldRev; // flip
 854                 } else { // normal case
 855                         $oldRev = $this->mOldRev;
 856                         $newRev = $this->mNewRev;
 857                 }
 858
 859                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 860                 if ( $nEdits > 0 ) {
 861                         $limit = 100; // use diff-multi-manyusers if too many users
 862                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 863                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 864                 }
 865                 return ''; // nothing
 866         }
 867
 868         /**
 869          * Get a notice about how many intermediate edits and users there are
 870          * @param $numEdits int
 871          * @param $numUsers int
 872          * @param $limit int
 873          * @return string
 874          */
 875         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 876                 if ( $numUsers > $limit ) {
 877                         $msg = 'diff-multi-manyusers';
 878                         $numUsers = $limit;
 879                 } else {
 880                         $msg = 'diff-multi';
 881                 }
 882                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 883         }
 884
 885         /**
 886          * Get a header for a specified revision.
 887          *
 888          * @param $rev Revision
 889          * @param $complete String: 'complete' to get the header wrapped depending
 890          *        the visibility of the revision and a link to edit the page.
 891          * @return String HTML fragment
 892          */
 893         private function getRevisionHeader( Revision $rev, $complete = '' ) {
 894                 $lang = $this->getLanguage();
 895                 $user = $this->getUser();
 896                 $revtimestamp = $rev->getTimestamp();
 897                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
 898                 $dateofrev = $lang->userDate( $revtimestamp, $user );
 899                 $timeofrev = $lang->userTime( $revtimestamp, $user );
 900
 901                 $header = $this->msg(
 902                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
 903                         $timestamp,
 904                         $dateofrev,
 905                         $timeofrev
 906                 )->escaped();
 907
 908                 if ( $complete !== 'complete' ) {
 909                         return $header;
 910                 }
 911
 912                 $title = $rev->getTitle();
 913
 914                 $header = Linker::linkKnown( $title, $header, array(),
 915                         array( 'oldid' => $rev->getID() ) );
 916
 917                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
 918                         $editQuery = array( 'action' => 'edit' );
 919                         if ( !$rev->isCurrent() ) {
 920                                 $editQuery['oldid'] = $rev->getID();
 921                         }
 922
 923                         $msg = $this->msg( $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold' )->escaped();
 924                         $header .= ' (' . Linker::linkKnown( $title, $msg, array(), $editQuery ) . ')';
 925                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
 926                                 $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 927                         }
 928                 } else {
 929                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 930                 }
 931
 932                 return $header;
 933         }
 934
 935         /**
 936          * Add the header to a diff body
 937          *
 938          * @return string
 939          */
 940         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
 941                 // shared.css sets diff in interface language/dir, but the actual content
 942                 // is often in a different language, mostly the page content language/dir
 943                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
 944                 $header = "<table class='$tableClass'>";
 945
 946                 if ( !$diff && !$otitle ) {
 947                         $header .= "
 948                         <tr valign='top'>
 949                         <td class='diff-ntitle'>{$ntitle}</td>
 950                         </tr>";
 951                         $multiColspan = 1;
 952                 } else {
 953                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
 954                                 $header .= "
 955                                 <col class='diff-marker' />
 956                                 <col class='diff-content' />
 957                                 <col class='diff-marker' />
 958                                 <col class='diff-content' />";
 959                                 $colspan = 2;
 960                                 $multiColspan = 4;
 961                         } else {
 962                                 $colspan = 1;
 963                                 $multiColspan = 2;
 964                         }
 965                         $header .= "
 966                         <tr valign='top'>
 967                         <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
 968                         <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
 969                         </tr>";
 970                 }
 971
 972                 if ( $multi != '' ) {
 973                         $header .= "<tr><td colspan='{$multiColspan}' align='center' class='diff-multi'>{$multi}</td></tr>";
 974                 }
 975                 if ( $notice != '' ) {
 976                         $header .= "<tr><td colspan='{$multiColspan}' align='center'>{$notice}</td></tr>";
 977                 }
 978
 979                 return $header . $diff . "</table>";
 980         }
 981
 982         /**
 983          * Use specified text instead of loading from the database
 984      * @deprecated since 1.WD
 985          */
 986         function setText( $oldText, $newText ) { #FIXME: no longer use this, use setContent()!
 987         wfDeprecated( __METHOD__, "1.WD" );
 988
 989         $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
 990         $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
 991
 992         $this->setContent( $oldContent, $newContent );
 993     }
 994
 995     /**
 996      * Use specified text instead of loading from the database
 997      * @since 1.WD
 998      */
 999     function setContent( Content $oldContent, Content $newContent ) {
1000         $this->mOldContent = $oldContent;
1001         $this->mNewContent = $newContent;
1002
1003         $this->mTextLoaded = 2;
1004         $this->mRevisionsLoaded = true;
1005     }
1006
1007         /**
1008          * Set the language in which the diff text is written
1009          * (Defaults to page content language).
1010          * @since 1.19
1011          */
1012         function setTextLanguage( $lang ) {
1013                 $this->mDiffLang = wfGetLangObj( $lang );
1014         }
1015
1016         /**
1017          * Load revision IDs
1018          */
1019         private function loadRevisionIds() {
1020                 if ( $this->mRevisionsIdsLoaded ) {
1021                         return;
1022                 }
1023
1024                 $this->mRevisionsIdsLoaded = true;
1025
1026                 $old = $this->mOldid;
1027                 $new = $this->mNewid;
1028
1029                 if ( $new === 'prev' ) {
1030                         # Show diff between revision $old and the previous one.
1031                         # Get previous one from DB.
1032                         $this->mNewid = intval( $old );
1033                         $this->mOldid = $this->getTitle()->getPreviousRevisionID( $this->mNewid );
1034                 } elseif ( $new === 'next' ) {
1035                         # Show diff between revision $old and the next one.
1036                         # Get next one from DB.
1037                         $this->mOldid = intval( $old );
1038                         $this->mNewid = $this->getTitle()->getNextRevisionID( $this->mOldid );
1039                         if ( $this->mNewid === false ) {
1040                                 # if no result, NewId points to the newest old revision. The only newer
1041                                 # revision is cur, which is "0".
1042                                 $this->mNewid = 0;
1043                         }
1044                 } else {
1045                         $this->mOldid = intval( $old );
1046                         $this->mNewid = intval( $new );
1047                         wfRunHooks( 'NewDifferenceEngine', array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ) );
1048                 }
1049         }
1050
1051         /**
1052          * Load revision metadata for the specified articles. If newid is 0, then compare
1053          * the old article in oldid to the current article; if oldid is 0, then
1054          * compare the current article to the immediately previous one (ignoring the
1055          * value of newid).
1056          *
1057          * If oldid is false, leave the corresponding revision object set
1058          * to false. This is impossible via ordinary user input, and is provided for
1059          * API convenience.
1060          *
1061          * @return bool
1062          */
1063         function loadRevisionData() {
1064                 if ( $this->mRevisionsLoaded ) {
1065                         return true;
1066                 }
1067
1068                 // Whether it succeeds or fails, we don't want to try again
1069                 $this->mRevisionsLoaded = true;
1070
1071                 $this->loadRevisionIds();
1072
1073                 // Load the new revision object
1074                 $this->mNewRev = $this->mNewid
1075                         ? Revision::newFromId( $this->mNewid )
1076                         : Revision::newFromTitle( $this->getTitle() );
1077
1078                 if ( !$this->mNewRev instanceof Revision ) {
1079                         return false;
1080                 }
1081
1082                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1083                 $this->mNewid = $this->mNewRev->getId();
1084                 $this->mNewPage = $this->mNewRev->getTitle();
1085
1086                 // Load the old revision object
1087                 $this->mOldRev = false;
1088                 if ( $this->mOldid ) {
1089                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1090                 } elseif ( $this->mOldid === 0 ) {
1091                         $rev = $this->mNewRev->getPrevious();
1092                         if ( $rev ) {
1093                                 $this->mOldid = $rev->getId();
1094                                 $this->mOldRev = $rev;
1095                         } else {
1096                                 // No previous revision; mark to show as first-version only.
1097                                 $this->mOldid = false;
1098                                 $this->mOldRev = false;
1099                         }
1100                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1101
1102                 if ( is_null( $this->mOldRev ) ) {
1103                         return false;
1104                 }
1105
1106                 if ( $this->mOldRev ) {
1107                         $this->mOldPage = $this->mOldRev->getTitle();
1108                 }
1109
1110                 return true;
1111         }
1112
1113         /**
1114          * Load the text of the revisions, as well as revision data.
1115          *
1116          * @return bool
1117          */
1118         function loadText() {
1119                 if ( $this->mTextLoaded == 2 ) {
1120                         return true;
1121                 } else {
1122                         // Whether it succeeds or fails, we don't want to try again
1123                         $this->mTextLoaded = 2;
1124                 }
1125
1126                 if ( !$this->loadRevisionData() ) {
1127                         return false;
1128                 }
1129                 if ( $this->mOldRev ) {
1130                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER );
1131                         if ( $this->mOldContent === false ) {
1132                                 return false;
1133                         }
1134                 }
1135                 if ( $this->mNewRev ) {
1136                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER );
1137                         if ( $this->mNewContent === false ) {
1138                                 return false;
1139                         }
1140                 }
1141                 return true;
1142         }
1143
1144         /**
1145          * Load the text of the new revision, not the old one
1146          *
1147          * @return bool
1148          */
1149         function loadNewText() {
1150                 if ( $this->mTextLoaded >= 1 ) {
1151                         return true;
1152                 } else {
1153                         $this->mTextLoaded = 1;
1154                 }
1155                 if ( !$this->loadRevisionData() ) {
1156                         return false;
1157                 }
1158                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER );
1159                 return true;
1160         }
1161 }