includes/diff/DifferenceEngine.php

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