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         /** @var int */
  39         public $mOldid;
  40
  41         /** @var int */
  42         public $mNewid;
  43
  44         private $mOldTags;
  45         private $mNewTags;
  46
  47         /** @var Content */
  48         public $mOldContent;
  49
  50         /** @var Content */
  51         public $mNewContent;
  52
  53         /** @var Language */
  54         protected $mDiffLang;
  55
  56         /** @var Title */
  57         public $mOldPage;
  58
  59         /** @var Title */
  60         public $mNewPage;
  61
  62         /** @var Revision */
  63         public $mOldRev;
  64
  65         /** @var Revision */
  66         public $mNewRev;
  67
  68         /** @var bool Have the revisions IDs been loaded */
  69         private $mRevisionsIdsLoaded = false;
  70
  71         /** @var bool Have the revisions been loaded */
  72         public $mRevisionsLoaded = false;
  73
  74         /** @var int How many text blobs have been loaded, 0, 1 or 2? */
  75         public $mTextLoaded = 0;
  76
  77         /** @var bool Was the diff fetched from cache? */
  78         public $mCacheHit = false;
  79
  80         /**
  81          * Set this to true to add debug info to the HTML output.
  82          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  83          * (bug 20601)
  84          */
  85         public $enableDebugComment = false;
  86
  87         /** @var bool If true, line X is not displayed when X is 1, for example
  88          *    to increase readability and conserve space with many small diffs.
  89          */
  90         protected $mReducedLineNumbers = false;
  91
  92         /** @var string Link to action=markpatrolled */
  93         protected $mMarkPatrolledLink = null;
  94
  95         /** @var bool Show rev_deleted content if allowed */
  96         protected $unhide = false;
  97
  98         /** @var bool Refresh the diff cache */
  99         protected $mRefreshCache = false;
 100
 101         /**#@-*/
 102
 103         /**
 104          * Constructor
 105          * @param IContextSource $context Context to use, anything else will be ignored
 106          * @param int $old Old ID we want to show and diff with.
 107          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 108          * @param int $rcid Deprecated, no longer used!
 109          * @param bool $refreshCache If set, refreshes the diff cache
 110          * @param bool $unhide If set, allow viewing deleted revs
 111          */
 112         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 113                 $refreshCache = false, $unhide = false
 114         ) {
 115                 if ( $context instanceof IContextSource ) {
 116                         $this->setContext( $context );
 117                 }
 118
 119                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 120
 121                 $this->mOldid = $old;
 122                 $this->mNewid = $new;
 123                 $this->mRefreshCache = $refreshCache;
 124                 $this->unhide = $unhide;
 125         }
 126
 127         /**
 128          * @param bool $value
 129          */
 130         public function setReducedLineNumbers( $value = true ) {
 131                 $this->mReducedLineNumbers = $value;
 132         }
 133
 134         /**
 135          * @return Language
 136          */
 137         public function getDiffLang() {
 138                 if ( $this->mDiffLang === null ) {
 139                         # Default language in which the diff text is written.
 140                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 141                 }
 142
 143                 return $this->mDiffLang;
 144         }
 145
 146         /**
 147          * @return bool
 148          */
 149         public function wasCacheHit() {
 150                 return $this->mCacheHit;
 151         }
 152
 153         /**
 154          * @return int
 155          */
 156         public function getOldid() {
 157                 $this->loadRevisionIds();
 158
 159                 return $this->mOldid;
 160         }
 161
 162         /**
 163          * @return bool|int
 164          */
 165         public function getNewid() {
 166                 $this->loadRevisionIds();
 167
 168                 return $this->mNewid;
 169         }
 170
 171         /**
 172          * Look up a special:Undelete link to the given deleted revision id,
 173          * as a workaround for being unable to load deleted diffs in currently.
 174          *
 175          * @param int $id Revision ID
 176          *
 177          * @return mixed URL or false
 178          */
 179         public function deletedLink( $id ) {
 180                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 181                         $dbr = wfGetDB( DB_SLAVE );
 182                         $row = $dbr->selectRow( 'archive', '*',
 183                                 [ 'ar_rev_id' => $id ],
 184                                 __METHOD__ );
 185                         if ( $row ) {
 186                                 $rev = Revision::newFromArchiveRow( $row );
 187                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 188
 189                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
 190                                         'target' => $title->getPrefixedText(),
 191                                         'timestamp' => $rev->getTimestamp()
 192                                 ] );
 193                         }
 194                 }
 195
 196                 return false;
 197         }
 198
 199         /**
 200          * Build a wikitext link toward a deleted revision, if viewable.
 201          *
 202          * @param int $id Revision ID
 203          *
 204          * @return string Wikitext fragment
 205          */
 206         public function deletedIdMarker( $id ) {
 207                 $link = $this->deletedLink( $id );
 208                 if ( $link ) {
 209                         return "[$link $id]";
 210                 } else {
 211                         return $id;
 212                 }
 213         }
 214
 215         private function showMissingRevision() {
 216                 $out = $this->getOutput();
 217
 218                 $missing = [];
 219                 if ( $this->mOldRev === null ||
 220                         ( $this->mOldRev && $this->mOldContent === null )
 221                 ) {
 222                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 223                 }
 224                 if ( $this->mNewRev === null ||
 225                         ( $this->mNewRev && $this->mNewContent === null )
 226                 ) {
 227                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 228                 }
 229
 230                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 231                 $msg = $this->msg( 'difference-missing-revision' )
 232                         ->params( $this->getLanguage()->listToText( $missing ) )
 233                         ->numParams( count( $missing ) )
 234                         ->parseAsBlock();
 235                 $out->addHTML( $msg );
 236         }
 237
 238         public function showDiffPage( $diffOnly = false ) {
 239                 # Allow frames except in certain special cases
 240                 $out = $this->getOutput();
 241                 $out->allowClickjacking();
 242                 $out->setRobotPolicy( 'noindex,nofollow' );
 243
 244                 // Allow extensions to add any extra output here
 245                 Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
 246
 247                 if ( !$this->loadRevisionData() ) {
 248                         $this->showMissingRevision();
 249
 250                         return;
 251                 }
 252
 253                 $user = $this->getUser();
 254                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 255                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 256                         $permErrors = wfMergeErrorArrays( $permErrors,
 257                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 258                 }
 259                 if ( count( $permErrors ) ) {
 260                         throw new PermissionsError( 'read', $permErrors );
 261                 }
 262
 263                 $rollback = '';
 264
 265                 $query = [];
 266                 # Carry over 'diffonly' param via navigation links
 267                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 268                         $query['diffonly'] = $diffOnly;
 269                 }
 270                 # Cascade unhide param in links for easy deletion browsing
 271                 if ( $this->unhide ) {
 272                         $query['unhide'] = 1;
 273                 }
 274
 275                 # Check if one of the revisions is deleted/suppressed
 276                 $deleted = $suppressed = false;
 277                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 278
 279                 $revisionTools = [];
 280
 281                 # mOldRev is false if the difference engine is called with a "vague" query for
 282                 # a diff between a version V and its previous version V' AND the version V
 283                 # is the first version of that article. In that case, V' does not exist.
 284                 if ( $this->mOldRev === false ) {
 285                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 286                         $samePage = true;
 287                         $oldHeader = '';
 288                         // Allow extensions to change the $oldHeader variable
 289                         Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
 290                 } else {
 291                         Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 292
 293                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 294                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 295                                 $samePage = true;
 296                         } else {
 297                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 298                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 299                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 300                                 $samePage = false;
 301                         }
 302
 303                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 304                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 305                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 306                                         if ( $rollbackLink ) {
 307                                                 $out->preventClickjacking();
 308                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 309                                         }
 310                                 }
 311
 312                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 313                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 314                                 ) {
 315                                         $undoLink = Html::element( 'a', [
 316                                                         'href' => $this->mNewPage->getLocalURL( [
 317                                                                 'action' => 'edit',
 318                                                                 'undoafter' => $this->mOldid,
 319                                                                 'undo' => $this->mNewid
 320                                                         ] ),
 321                                                         'title' => Linker::titleAttrib( 'undo' ),
 322                                                 ],
 323                                                 $this->msg( 'editundo' )->text()
 324                                         );
 325                                         $revisionTools['mw-diff-undo'] = $undoLink;
 326                                 }
 327                         }
 328
 329                         # Make "previous revision link"
 330                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 331                                 $prevlink = Linker::linkKnown(
 332                                         $this->mOldPage,
 333                                         $this->msg( 'previousdiff' )->escaped(),
 334                                         [ 'id' => 'differences-prevlink' ],
 335                                         [ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
 336                                 );
 337                         } else {
 338                                 $prevlink = '&#160;';
 339                         }
 340
 341                         if ( $this->mOldRev->isMinor() ) {
 342                                 $oldminor = ChangesList::flag( 'minor' );
 343                         } else {
 344                                 $oldminor = '';
 345                         }
 346
 347                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 348                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 349                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );
 350
 351                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 352                                 '<div id="mw-diff-otitle2">' .
 353                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 354                                 '<div id="mw-diff-otitle3">' . $oldminor .
 355                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 356                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 357                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 358
 359                         // Allow extensions to change the $oldHeader variable
 360                         Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
 361                                 $diffOnly, $ldel, $this->unhide ] );
 362
 363                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 364                                 $deleted = true; // old revisions text is hidden
 365                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 366                                         $suppressed = true; // also suppressed
 367                                 }
 368                         }
 369
 370                         # Check if this user can see the revisions
 371                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 372                                 $allowed = false;
 373                         }
 374                 }
 375
 376                 # Make "next revision link"
 377                 # Skip next link on the top revision
 378                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 379                         $nextlink = Linker::linkKnown(
 380                                 $this->mNewPage,
 381                                 $this->msg( 'nextdiff' )->escaped(),
 382                                 [ 'id' => 'differences-nextlink' ],
 383                                 [ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
 384                         );
 385                 } else {
 386                         $nextlink = '&#160;';
 387                 }
 388
 389                 if ( $this->mNewRev->isMinor() ) {
 390                         $newminor = ChangesList::flag( 'minor' );
 391                 } else {
 392                         $newminor = '';
 393                 }
 394
 395                 # Handle RevisionDelete links...
 396                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 397
 398                 # Allow extensions to define their own revision tools
 399                 Hooks::run( 'DiffRevisionTools',
 400                         [ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
 401                 $formattedRevisionTools = [];
 402                 // Put each one in parentheses (poor man's button)
 403                 foreach ( $revisionTools as $key => $tool ) {
 404                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 405                         $element = Html::rawElement(
 406                                 'span',
 407                                 [ 'class' => $toolClass ],
 408                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 409                         );
 410                         $formattedRevisionTools[] = $element;
 411                 }
 412                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 413                         ' ' . implode( ' ', $formattedRevisionTools );
 414                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );
 415
 416                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 417                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 418                         " $rollback</div>" .
 419                         '<div id="mw-diff-ntitle3">' . $newminor .
 420                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 421                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 422                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 423
 424                 // Allow extensions to change the $newHeader variable
 425                 Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
 426                         $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
 427
 428                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 429                         $deleted = true; // new revisions text is hidden
 430                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 431                                 $suppressed = true; // also suppressed
 432                         }
 433                 }
 434
 435                 # If the diff cannot be shown due to a deleted revision, then output
 436                 # the diff header and links to unhide (if available)...
 437                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 438                         $this->showDiffStyle();
 439                         $multi = $this->getMultiNotice();
 440                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 441                         if ( !$allowed ) {
 442                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 443                                 # Give explanation for why revision is not visible
 444                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 445                                         [ $msg ] );
 446                         } else {
 447                                 # Give explanation and add a link to view the diff...
 448                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
 449                                 $link = $this->getTitle()->getFullURL( $query );
 450                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 451                                 $out->wrapWikiMsg(
 452                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 453                                         [ $msg, $link ]
 454                                 );
 455                         }
 456                 # Otherwise, output a regular diff...
 457                 } else {
 458                         # Add deletion notice if the user is viewing deleted content
 459                         $notice = '';
 460                         if ( $deleted ) {
 461                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 462                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 463                                         $this->msg( $msg )->parse() .
 464                                         "</div>\n";
 465                         }
 466                         $this->showDiff( $oldHeader, $newHeader, $notice );
 467                         if ( !$diffOnly ) {
 468                                 $this->renderNewRevision();
 469                         }
 470                 }
 471         }
 472
 473         /**
 474          * Build a link to mark a change as patrolled.
 475          *
 476          * Returns empty string if there's either no revision to patrol or the user is not allowed to.
 477          * Side effect: When the patrol link is build, this method will call
 478          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 479          *
 480          * @return string HTML or empty string
 481          */
 482         protected function markPatrolledLink() {
 483                 if ( $this->mMarkPatrolledLink === null ) {
 484                         $linkInfo = $this->getMarkPatrolledLinkInfo();
 485                         // If false, there is no patrol link needed/allowed
 486                         if ( !$linkInfo ) {
 487                                 $this->mMarkPatrolledLink = '';
 488                         } else {
 489                                 $this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
 490                                         Linker::linkKnown(
 491                                                 $this->mNewPage,
 492                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 493                                                 [],
 494                                                 [
 495                                                         'action' => 'markpatrolled',
 496                                                         'rcid' => $linkInfo['rcid'],
 497                                                         'token' => $linkInfo['token'],
 498                                                 ]
 499                                         ) . ']</span>';
 500                                 // Allow extensions to change the markpatrolled link
 501                                 Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
 502                                         &$this->mMarkPatrolledLink, $linkInfo['rcid'], $linkInfo['token'] ] );
 503                         }
 504                 }
 505                 return $this->mMarkPatrolledLink;
 506         }
 507
 508         /**
 509          * Returns an array of meta data needed to build a "mark as patrolled" link and
 510          * adds the mediawiki.page.patrol.ajax to the output.
 511          *
 512          * @return array|false An array of meta data for a patrol link (rcid & token)
 513          *  or false if no link is needed
 514          */
 515         protected function getMarkPatrolledLinkInfo() {
 516                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 517
 518                 $user = $this->getUser();
 519
 520                 // Prepare a change patrol link, if applicable
 521                 if (
 522                         // Is patrolling enabled and the user allowed to?
 523                         $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 524                         // Only do this if the revision isn't more than 6 hours older
 525                         // than the Max RC age (6h because the RC might not be cleaned out regularly)
 526                         RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 527                 ) {
 528                         // Look for an unpatrolled change corresponding to this diff
 529                         $db = wfGetDB( DB_SLAVE );
 530                         $change = RecentChange::newFromConds(
 531                                 [
 532                                         'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 533                                         'rc_this_oldid' => $this->mNewid,
 534                                         'rc_patrolled' => 0
 535                                 ],
 536                                 __METHOD__
 537                         );
 538
 539                         if ( $change && !$change->getPerformer()->equals( $user ) ) {
 540                                 $rcid = $change->getAttribute( 'rc_id' );
 541                         } else {
 542                                 // None found or the page has been created by the current user.
 543                                 // If the user could patrol this it already would be patrolled
 544                                 $rcid = 0;
 545                         }
 546
 547                         // Allow extensions to possibly change the rcid here
 548                         // For example the rcid might be set to zero due to the user
 549                         // being the same as the performer of the change but an extension
 550                         // might still want to show it under certain conditions
 551                         Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
 552
 553                         // Build the link
 554                         if ( $rcid ) {
 555                                 $this->getOutput()->preventClickjacking();
 556                                 if ( $wgEnableAPI && $wgEnableWriteAPI
 557                                         && $user->isAllowed( 'writeapi' )
 558                                 ) {
 559                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 560                                 }
 561
 562                                 $token = $user->getEditToken( $rcid );
 563                                 return [
 564                                         'rcid' => $rcid,
 565                                         'token' => $token,
 566                                 ];
 567                         }
 568                 }
 569
 570                 // No mark as patrolled link applicable
 571                 return false;
 572         }
 573
 574         /**
 575          * @param Revision $rev
 576          *
 577          * @return string
 578          */
 579         protected function revisionDeleteLink( $rev ) {
 580                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 581                 if ( $link !== '' ) {
 582                         $link = '&#160;&#160;&#160;' . $link . ' ';
 583                 }
 584
 585                 return $link;
 586         }
 587
 588         /**
 589          * Show the new revision of the page.
 590          */
 591         public function renderNewRevision() {
 592                 $out = $this->getOutput();
 593                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 594                 # Add "current version as of X" title
 595                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 596                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 597                 # Page content may be handled by a hooked call instead...
 598                 # @codingStandardsIgnoreStart Ignoring long lines.
 599                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 600                         $this->loadNewText();
 601                         $out->setRevisionId( $this->mNewid );
 602                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 603                         $out->setArticleFlag( true );
 604
 605                         // NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 606                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 607                                 // This needs to be synchronised with Article::showCssOrJsPage(), which sucks
 608                                 // Give hooks a chance to customise the output
 609                                 // @todo standardize this crap into one function
 610                                 if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', [ $this->mNewContent, $this->mNewPage, $out ] ) ) {
 611                                         // NOTE: deprecated hook, B/C only
 612                                         // use the content object's own rendering
 613                                         $cnt = $this->mNewRev->getContent();
 614                                         $po = $cnt ? $cnt->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() ) : null;
 615                                         if ( $po ) {
 616                                                 $out->addParserOutputContent( $po );
 617                                         }
 618                                 }
 619                         } elseif ( !Hooks::run( 'ArticleContentViewCustom', [ $this->mNewContent, $this->mNewPage, $out ] ) ) {
 620                                 // Handled by extension
 621                         } elseif ( !ContentHandler::runLegacyHooks( 'ArticleViewCustom', [ $this->mNewContent, $this->mNewPage, $out ] ) ) {
 622                                 // NOTE: deprecated hook, B/C only
 623                                 // Handled by extension
 624                         } else {
 625                                 // Normal page
 626                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 627                                         // If the Title stored in the context is the same as the one
 628                                         // of the new revision, we can use its associated WikiPage
 629                                         // object.
 630                                         $wikiPage = $this->getWikiPage();
 631                                 } else {
 632                                         // Otherwise we need to create our own WikiPage object
 633                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 634                                 }
 635
 636                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 637
 638                                 # WikiPage::getParserOutput() should not return false, but just in case
 639                                 if ( $parserOutput ) {
 640                                         // Allow extensions to change parser output here
 641                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput', [ $this, $out, $parserOutput, $wikiPage ] ) ) {
 642                                                 $out->addParserOutput( $parserOutput );
 643                                         }
 644                                 }
 645                         }
 646                 }
 647                 # @codingStandardsIgnoreEnd
 648
 649                 // Allow extensions to optionally not show the final patrolled link
 650                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 651                         # Add redundant patrol link on bottom...
 652                         $out->addHTML( $this->markPatrolledLink() );
 653                 }
 654         }
 655
 656         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 657                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 658
 659                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 660                         $parserOptions->setEditSection( false );
 661                 }
 662
 663                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 664
 665                 return $parserOutput;
 666         }
 667
 668         /**
 669          * Get the diff text, send it to the OutputPage object
 670          * Returns false if the diff could not be generated, otherwise returns true
 671          *
 672          * @param string|bool $otitle Header for old text or false
 673          * @param string|bool $ntitle Header for new text or false
 674          * @param string $notice HTML between diff header and body
 675          *
 676          * @return bool
 677          */
 678         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 679                 // Allow extensions to affect the output here
 680                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 681
 682                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 683                 if ( $diff === false ) {
 684                         $this->showMissingRevision();
 685
 686                         return false;
 687                 } else {
 688                         $this->showDiffStyle();
 689                         $this->getOutput()->addHTML( $diff );
 690
 691                         return true;
 692                 }
 693         }
 694
 695         /**
 696          * Add style sheets and supporting JS for diff display.
 697          */
 698         public function showDiffStyle() {
 699                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 700         }
 701
 702         /**
 703          * Get complete diff table, including header
 704          *
 705          * @param string|bool $otitle Header for old text or false
 706          * @param string|bool $ntitle Header for new text or false
 707          * @param string $notice HTML between diff header and body
 708          *
 709          * @return mixed
 710          */
 711         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 712                 $body = $this->getDiffBody();
 713                 if ( $body === false ) {
 714                         return false;
 715                 }
 716
 717                 $multi = $this->getMultiNotice();
 718                 // Display a message when the diff is empty
 719                 if ( $body === '' ) {
 720                         $notice .= '<div class="mw-diff-empty">' .
 721                                 $this->msg( 'diff-empty' )->parse() .
 722                                 "</div>\n";
 723                 }
 724
 725                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 726         }
 727
 728         /**
 729          * Get the diff table body, without header
 730          *
 731          * @return mixed (string/false)
 732          */
 733         public function getDiffBody() {
 734                 $this->mCacheHit = true;
 735                 // Check if the diff should be hidden from this user
 736                 if ( !$this->loadRevisionData() ) {
 737                         return false;
 738                 } elseif ( $this->mOldRev &&
 739                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 740                 ) {
 741                         return false;
 742                 } elseif ( $this->mNewRev &&
 743                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 744                 ) {
 745                         return false;
 746                 }
 747                 // Short-circuit
 748                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 749                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 750                 ) {
 751                         if ( !Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 752                                 return '';
 753                         }
 754                 }
 755                 // Cacheable?
 756                 $key = false;
 757                 $cache = ObjectCache::getMainWANInstance();
 758                 if ( $this->mOldid && $this->mNewid ) {
 759                         $key = $this->getDiffBodyCacheKey();
 760
 761                         // Try cache
 762                         if ( !$this->mRefreshCache ) {
 763                                 $difftext = $cache->get( $key );
 764                                 if ( $difftext ) {
 765                                         wfIncrStats( 'diff_cache.hit' );
 766                                         $difftext = $this->localiseLineNumbers( $difftext );
 767                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 768
 769                                         return $difftext;
 770                                 }
 771                         } // don't try to load but save the result
 772                 }
 773                 $this->mCacheHit = false;
 774
 775                 // Loadtext is permission safe, this just clears out the diff
 776                 if ( !$this->loadText() ) {
 777                         return false;
 778                 }
 779
 780                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 781
 782                 // Save to cache for 7 days
 783                 if ( !Hooks::run( 'AbortDiffCache', [ &$this ] ) ) {
 784                         wfIncrStats( 'diff_cache.uncacheable' );
 785                 } elseif ( $key !== false && $difftext !== false ) {
 786                         wfIncrStats( 'diff_cache.miss' );
 787                         $cache->set( $key, $difftext, 7 * 86400 );
 788                 } else {
 789                         wfIncrStats( 'diff_cache.uncacheable' );
 790                 }
 791                 // Replace line numbers with the text in the user's language
 792                 if ( $difftext !== false ) {
 793                         $difftext = $this->localiseLineNumbers( $difftext );
 794                 }
 795
 796                 return $difftext;
 797         }
 798
 799         /**
 800          * Returns the cache key for diff body text or content.
 801          *
 802          * @since 1.23
 803          *
 804          * @throws MWException
 805          * @return string
 806          */
 807         protected function getDiffBodyCacheKey() {
 808                 if ( !$this->mOldid || !$this->mNewid ) {
 809                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 810                 }
 811
 812                 return wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 813                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 814         }
 815
 816         /**
 817          * Generate a diff, no caching.
 818          *
 819          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 820          * serialization of the given Content objects. This will fail if $old or $new are not
 821          * instances of TextContent.
 822          *
 823          * Subclasses may override this to provide a different rendering for the diff,
 824          * perhaps taking advantage of the content's native form. This is required for all content
 825          * models that are not text based.
 826          *
 827          * @since 1.21
 828          *
 829          * @param Content $old Old content
 830          * @param Content $new New content
 831          *
 832          * @throws MWException If old or new content is not an instance of TextContent.
 833          * @return bool|string
 834          */
 835         public function generateContentDiffBody( Content $old, Content $new ) {
 836                 if ( !( $old instanceof TextContent ) ) {
 837                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 838                                 "override generateContentDiffBody to fix this." );
 839                 }
 840
 841                 if ( !( $new instanceof TextContent ) ) {
 842                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 843                                 . "override generateContentDiffBody to fix this." );
 844                 }
 845
 846                 $otext = $old->serialize();
 847                 $ntext = $new->serialize();
 848
 849                 return $this->generateTextDiffBody( $otext, $ntext );
 850         }
 851
 852         /**
 853          * Generate a diff, no caching
 854          *
 855          * @param string $otext Old text, must be already segmented
 856          * @param string $ntext New text, must be already segmented
 857          *
 858          * @return bool|string
 859          * @deprecated since 1.21, use generateContentDiffBody() instead!
 860          */
 861         public function generateDiffBody( $otext, $ntext ) {
 862                 ContentHandler::deprecated( __METHOD__, "1.21" );
 863
 864                 return $this->generateTextDiffBody( $otext, $ntext );
 865         }
 866
 867         /**
 868          * Generate a diff, no caching
 869          *
 870          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 871          *
 872          * @param string $otext Old text, must be already segmented
 873          * @param string $ntext New text, must be already segmented
 874          *
 875          * @return bool|string
 876          */
 877         public function generateTextDiffBody( $otext, $ntext ) {
 878                 $diff = function() use ( $otext, $ntext ) {
 879                         $time = microtime( true );
 880
 881                         $result = $this->textDiff( $otext, $ntext );
 882
 883                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 884                         $this->getStats()->timing( 'diff_time', $time );
 885                         // Log requests slower than 99th percentile
 886                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 887                                 wfDebugLog( 'diff',
 888                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 889                         }
 890
 891                         return $result;
 892                 };
 893
 894                 $error = function( $status ) {
 895                         throw new FatalError( $status->getWikiText() );
 896                 };
 897
 898                 // Use PoolCounter if the diff looks like it can be expensive
 899                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 900                         $work = new PoolCounterWorkViaCallback( 'diff',
 901                                 md5( $otext ) . md5( $ntext ),
 902                                 [ 'doWork' => $diff, 'error' => $error ]
 903                         );
 904                         return $work->execute();
 905                 }
 906
 907                 return $diff();
 908         }
 909
 910         /**
 911          * Generates diff, to be wrapped internally in a logging/instrumentation
 912          *
 913          * @param string $otext Old text, must be already segmented
 914          * @param string $ntext New text, must be already segmented
 915          * @return bool|string
 916          */
 917         protected function textDiff( $otext, $ntext ) {
 918                 global $wgExternalDiffEngine, $wgContLang;
 919
 920                 $otext = str_replace( "\r\n", "\n", $otext );
 921                 $ntext = str_replace( "\r\n", "\n", $ntext );
 922
 923                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 924                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 925                         $wgExternalDiffEngine = false;
 926                 }
 927
 928                 if ( $wgExternalDiffEngine == 'wikidiff2' ) {
 929                         if ( function_exists( 'wikidiff2_do_diff' ) ) {
 930                                 # Better external diff engine, the 2 may some day be dropped
 931                                 # This one does the escaping and segmenting itself
 932                                 $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 933                                 $text .= $this->debug( 'wikidiff2' );
 934
 935                                 return $text;
 936                         }
 937                 } elseif ( $wgExternalDiffEngine !== false ) {
 938                         # Diff via the shell
 939                         $tmpDir = wfTempDir();
 940                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 941                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 942
 943                         $tempFile1 = fopen( $tempName1, "w" );
 944                         if ( !$tempFile1 ) {
 945                                 return false;
 946                         }
 947                         $tempFile2 = fopen( $tempName2, "w" );
 948                         if ( !$tempFile2 ) {
 949                                 return false;
 950                         }
 951                         fwrite( $tempFile1, $otext );
 952                         fwrite( $tempFile2, $ntext );
 953                         fclose( $tempFile1 );
 954                         fclose( $tempFile2 );
 955                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 956                         $difftext = wfShellExec( $cmd );
 957                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 958                         unlink( $tempName1 );
 959                         unlink( $tempName2 );
 960
 961                         return $difftext;
 962                 }
 963
 964                 # Native PHP diff
 965                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 966                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 967                 $diffs = new Diff( $ota, $nta );
 968                 $formatter = new TableDiffFormatter();
 969                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 970
 971                 return $difftext;
 972         }
 973
 974         /**
 975          * Generate a debug comment indicating diff generating time,
 976          * server node, and generator backend.
 977          *
 978          * @param string $generator : What diff engine was used
 979          *
 980          * @return string
 981          */
 982         protected function debug( $generator = "internal" ) {
 983                 global $wgShowHostnames;
 984                 if ( !$this->enableDebugComment ) {
 985                         return '';
 986                 }
 987                 $data = [ $generator ];
 988                 if ( $wgShowHostnames ) {
 989                         $data[] = wfHostname();
 990                 }
 991                 $data[] = wfTimestamp( TS_DB );
 992
 993                 return "<!-- diff generator: " .
 994                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
 995                         " -->\n";
 996         }
 997
 998         /**
 999          * Replace line numbers with the text in the user's language
1000          *
1001          * @param string $text
1002          *
1003          * @return mixed
1004          */
1005         public function localiseLineNumbers( $text ) {
1006                 return preg_replace_callback(
1007                         '/<!--LINE (\d+)-->/',
1008                         [ &$this, 'localiseLineNumbersCb' ],
1009                         $text
1010                 );
1011         }
1012
1013         public function localiseLineNumbersCb( $matches ) {
1014                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1015                         return '';
1016                 }
1017
1018                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1019         }
1020
1021         /**
1022          * If there are revisions between the ones being compared, return a note saying so.
1023          *
1024          * @return string
1025          */
1026         public function getMultiNotice() {
1027                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1028                         return '';
1029                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1030                         // Comparing two different pages? Count would be meaningless.
1031                         return '';
1032                 }
1033
1034                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1035                         $oldRev = $this->mNewRev; // flip
1036                         $newRev = $this->mOldRev; // flip
1037                 } else { // normal case
1038                         $oldRev = $this->mOldRev;
1039                         $newRev = $this->mNewRev;
1040                 }
1041
1042                 // Sanity: don't show the notice if too many rows must be scanned
1043                 // @todo show some special message for that case
1044                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1045                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1046                         $limit = 100; // use diff-multi-manyusers if too many users
1047                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1048                         $numUsers = count( $users );
1049
1050                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1051                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1052                         }
1053
1054                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1055                 }
1056
1057                 return ''; // nothing
1058         }
1059
1060         /**
1061          * Get a notice about how many intermediate edits and users there are
1062          *
1063          * @param int $numEdits
1064          * @param int $numUsers
1065          * @param int $limit
1066          *
1067          * @return string
1068          */
1069         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1070                 if ( $numUsers === 0 ) {
1071                         $msg = 'diff-multi-sameuser';
1072                 } elseif ( $numUsers > $limit ) {
1073                         $msg = 'diff-multi-manyusers';
1074                         $numUsers = $limit;
1075                 } else {
1076                         $msg = 'diff-multi-otherusers';
1077                 }
1078
1079                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1080         }
1081
1082         /**
1083          * Get a header for a specified revision.
1084          *
1085          * @param Revision $rev
1086          * @param string $complete 'complete' to get the header wrapped depending
1087          *        the visibility of the revision and a link to edit the page.
1088          *
1089          * @return string HTML fragment
1090          */
1091         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
1092                 $lang = $this->getLanguage();
1093                 $user = $this->getUser();
1094                 $revtimestamp = $rev->getTimestamp();
1095                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1096                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1097                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1098
1099                 $header = $this->msg(
1100                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1101                         $timestamp,
1102                         $dateofrev,
1103                         $timeofrev
1104                 )->escaped();
1105
1106                 if ( $complete !== 'complete' ) {
1107                         return $header;
1108                 }
1109
1110                 $title = $rev->getTitle();
1111
1112                 $header = Linker::linkKnown( $title, $header, [],
1113                         [ 'oldid' => $rev->getId() ] );
1114
1115                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1116                         $editQuery = [ 'action' => 'edit' ];
1117                         if ( !$rev->isCurrent() ) {
1118                                 $editQuery['oldid'] = $rev->getId();
1119                         }
1120
1121                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1122                         $msg = $this->msg( $key )->escaped();
1123                         $editLink = $this->msg( 'parentheses' )->rawParams(
1124                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1125                         $header .= ' ' . Html::rawElement(
1126                                 'span',
1127                                 [ 'class' => 'mw-diff-edit' ],
1128                                 $editLink
1129                         );
1130                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1131                                 $header = Html::rawElement(
1132                                         'span',
1133                                         [ 'class' => 'history-deleted' ],
1134                                         $header
1135                                 );
1136                         }
1137                 } else {
1138                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1139                 }
1140
1141                 return $header;
1142         }
1143
1144         /**
1145          * Add the header to a diff body
1146          *
1147          * @param string $diff Diff body
1148          * @param string $otitle Old revision header
1149          * @param string $ntitle New revision header
1150          * @param string $multi Notice telling user that there are intermediate
1151          *   revisions between the ones being compared
1152          * @param string $notice Other notices, e.g. that user is viewing deleted content
1153          *
1154          * @return string
1155          */
1156         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1157                 // shared.css sets diff in interface language/dir, but the actual content
1158                 // is often in a different language, mostly the page content language/dir
1159                 $header = Html::openElement( 'table', [
1160                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1161                         'data-mw' => 'interface',
1162                 ] );
1163                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1164
1165                 if ( !$diff && !$otitle ) {
1166                         $header .= "
1167                         <tr style='vertical-align: top;' lang='{$userLang}'>
1168                         <td class='diff-ntitle'>{$ntitle}</td>
1169                         </tr>";
1170                         $multiColspan = 1;
1171                 } else {
1172                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1173                                 $header .= "
1174                                 <col class='diff-marker' />
1175                                 <col class='diff-content' />
1176                                 <col class='diff-marker' />
1177                                 <col class='diff-content' />";
1178                                 $colspan = 2;
1179                                 $multiColspan = 4;
1180                         } else {
1181                                 $colspan = 1;
1182                                 $multiColspan = 2;
1183                         }
1184                         if ( $otitle || $ntitle ) {
1185                                 $header .= "
1186                                 <tr style='vertical-align: top;' lang='{$userLang}'>
1187                                 <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
1188                                 <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
1189                                 </tr>";
1190                         }
1191                 }
1192
1193                 if ( $multi != '' ) {
1194                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1195                                 "class='diff-multi' lang='{$userLang}'>{$multi}</td></tr>";
1196                 }
1197                 if ( $notice != '' ) {
1198                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1199                                 "lang='{$userLang}'>{$notice}</td></tr>";
1200                 }
1201
1202                 return $header . $diff . "</table>";
1203         }
1204
1205         /**
1206          * Use specified text instead of loading from the database
1207          * @param Content $oldContent
1208          * @param Content $newContent
1209          * @since 1.21
1210          */
1211         public function setContent( Content $oldContent, Content $newContent ) {
1212                 $this->mOldContent = $oldContent;
1213                 $this->mNewContent = $newContent;
1214
1215                 $this->mTextLoaded = 2;
1216                 $this->mRevisionsLoaded = true;
1217         }
1218
1219         /**
1220          * Set the language in which the diff text is written
1221          * (Defaults to page content language).
1222          * @param Language|string $lang
1223          * @since 1.19
1224          */
1225         public function setTextLanguage( $lang ) {
1226                 $this->mDiffLang = wfGetLangObj( $lang );
1227         }
1228
1229         /**
1230          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1231          * to a pair of actual integers representing revision ids.
1232          *
1233          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1234          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1235          *
1236          * @return int[] List of two revision ids, older first, later second.
1237          *     Zero signifies invalid argument passed.
1238          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1239          */
1240         public function mapDiffPrevNext( $old, $new ) {
1241                 if ( $new === 'prev' ) {
1242                         // Show diff between revision $old and the previous one. Get previous one from DB.
1243                         $newid = intval( $old );
1244                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1245                 } elseif ( $new === 'next' ) {
1246                         // Show diff between revision $old and the next one. Get next one from DB.
1247                         $oldid = intval( $old );
1248                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1249                 } else {
1250                         $oldid = intval( $old );
1251                         $newid = intval( $new );
1252                 }
1253
1254                 return [ $oldid, $newid ];
1255         }
1256
1257         /**
1258          * Load revision IDs
1259          */
1260         private function loadRevisionIds() {
1261                 if ( $this->mRevisionsIdsLoaded ) {
1262                         return;
1263                 }
1264
1265                 $this->mRevisionsIdsLoaded = true;
1266
1267                 $old = $this->mOldid;
1268                 $new = $this->mNewid;
1269
1270                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1271                 if ( $new === 'next' && $this->mNewid === false ) {
1272                         # if no result, NewId points to the newest old revision. The only newer
1273                         # revision is cur, which is "0".
1274                         $this->mNewid = 0;
1275                 }
1276
1277                 Hooks::run(
1278                         'NewDifferenceEngine',
1279                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1280                 );
1281         }
1282
1283         /**
1284          * Load revision metadata for the specified articles. If newid is 0, then compare
1285          * the old article in oldid to the current article; if oldid is 0, then
1286          * compare the current article to the immediately previous one (ignoring the
1287          * value of newid).
1288          *
1289          * If oldid is false, leave the corresponding revision object set
1290          * to false. This is impossible via ordinary user input, and is provided for
1291          * API convenience.
1292          *
1293          * @return bool
1294          */
1295         public function loadRevisionData() {
1296                 if ( $this->mRevisionsLoaded ) {
1297                         return true;
1298                 }
1299
1300                 // Whether it succeeds or fails, we don't want to try again
1301                 $this->mRevisionsLoaded = true;
1302
1303                 $this->loadRevisionIds();
1304
1305                 // Load the new revision object
1306                 if ( $this->mNewid ) {
1307                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1308                 } else {
1309                         $this->mNewRev = Revision::newFromTitle(
1310                                 $this->getTitle(),
1311                                 false,
1312                                 Revision::READ_NORMAL
1313                         );
1314                 }
1315
1316                 if ( !$this->mNewRev instanceof Revision ) {
1317                         return false;
1318                 }
1319
1320                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1321                 $this->mNewid = $this->mNewRev->getId();
1322                 $this->mNewPage = $this->mNewRev->getTitle();
1323
1324                 // Load the old revision object
1325                 $this->mOldRev = false;
1326                 if ( $this->mOldid ) {
1327                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1328                 } elseif ( $this->mOldid === 0 ) {
1329                         $rev = $this->mNewRev->getPrevious();
1330                         if ( $rev ) {
1331                                 $this->mOldid = $rev->getId();
1332                                 $this->mOldRev = $rev;
1333                         } else {
1334                                 // No previous revision; mark to show as first-version only.
1335                                 $this->mOldid = false;
1336                                 $this->mOldRev = false;
1337                         }
1338                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1339
1340                 if ( is_null( $this->mOldRev ) ) {
1341                         return false;
1342                 }
1343
1344                 if ( $this->mOldRev ) {
1345                         $this->mOldPage = $this->mOldRev->getTitle();
1346                 }
1347
1348                 // Load tags information for both revisions
1349                 $dbr = wfGetDB( DB_SLAVE );
1350                 if ( $this->mOldid !== false ) {
1351                         $this->mOldTags = $dbr->selectField(
1352                                 'tag_summary',
1353                                 'ts_tags',
1354                                 [ 'ts_rev_id' => $this->mOldid ],
1355                                 __METHOD__
1356                         );
1357                 } else {
1358                         $this->mOldTags = false;
1359                 }
1360                 $this->mNewTags = $dbr->selectField(
1361                         'tag_summary',
1362                         'ts_tags',
1363                         [ 'ts_rev_id' => $this->mNewid ],
1364                         __METHOD__
1365                 );
1366
1367                 return true;
1368         }
1369
1370         /**
1371          * Load the text of the revisions, as well as revision data.
1372          *
1373          * @return bool
1374          */
1375         public function loadText() {
1376                 if ( $this->mTextLoaded == 2 ) {
1377                         return true;
1378                 }
1379
1380                 // Whether it succeeds or fails, we don't want to try again
1381                 $this->mTextLoaded = 2;
1382
1383                 if ( !$this->loadRevisionData() ) {
1384                         return false;
1385                 }
1386
1387                 if ( $this->mOldRev ) {
1388                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1389                         if ( $this->mOldContent === null ) {
1390                                 return false;
1391                         }
1392                 }
1393
1394                 if ( $this->mNewRev ) {
1395                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1396                         if ( $this->mNewContent === null ) {
1397                                 return false;
1398                         }
1399                 }
1400
1401                 return true;
1402         }
1403
1404         /**
1405          * Load the text of the new revision, not the old one
1406          *
1407          * @return bool
1408          */
1409         public function loadNewText() {
1410                 if ( $this->mTextLoaded >= 1 ) {
1411                         return true;
1412                 }
1413
1414                 $this->mTextLoaded = 1;
1415
1416                 if ( !$this->loadRevisionData() ) {
1417                         return false;
1418                 }
1419
1420                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1421
1422                 return true;
1423         }
1424
1425 }