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 use MediaWiki\MediaWikiServices;
  24
  25 /** @deprecated use class constant instead */
  26 define( 'MW_DIFF_VERSION', '1.11a' );
  27
  28 /**
  29  * @todo document
  30  * @ingroup DifferenceEngine
  31  */
  32 class DifferenceEngine extends ContextSource {
  33         /**
  34          * Constant to indicate diff cache compatibility.
  35          * Bump this when changing the diff formatting in a way that
  36          * fixes important bugs or such to force cached diff views to
  37          * clear.
  38          */
  39         const DIFF_VERSION = MW_DIFF_VERSION;
  40
  41         /** @var int */
  42         public $mOldid;
  43
  44         /** @var int */
  45         public $mNewid;
  46
  47         private $mOldTags;
  48         private $mNewTags;
  49
  50         /** @var Content */
  51         public $mOldContent;
  52
  53         /** @var Content */
  54         public $mNewContent;
  55
  56         /** @var Language */
  57         protected $mDiffLang;
  58
  59         /** @var Title */
  60         public $mOldPage;
  61
  62         /** @var Title */
  63         public $mNewPage;
  64
  65         /** @var Revision */
  66         public $mOldRev;
  67
  68         /** @var Revision */
  69         public $mNewRev;
  70
  71         /** @var bool Have the revisions IDs been loaded */
  72         private $mRevisionsIdsLoaded = false;
  73
  74         /** @var bool Have the revisions been loaded */
  75         public $mRevisionsLoaded = false;
  76
  77         /** @var int How many text blobs have been loaded, 0, 1 or 2? */
  78         public $mTextLoaded = 0;
  79
  80         /** @var bool Was the diff fetched from cache? */
  81         public $mCacheHit = false;
  82
  83         /**
  84          * Set this to true to add debug info to the HTML output.
  85          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  86          * (T22601)
  87          */
  88         public $enableDebugComment = false;
  89
  90         /** @var bool If true, line X is not displayed when X is 1, for example
  91          *    to increase readability and conserve space with many small diffs.
  92          */
  93         protected $mReducedLineNumbers = false;
  94
  95         /** @var string Link to action=markpatrolled */
  96         protected $mMarkPatrolledLink = null;
  97
  98         /** @var bool Show rev_deleted content if allowed */
  99         protected $unhide = false;
 100
 101         /** @var bool Refresh the diff cache */
 102         protected $mRefreshCache = false;
 103
 104         /**#@-*/
 105
 106         /**
 107          * @param IContextSource $context Context to use, anything else will be ignored
 108          * @param int $old Old ID we want to show and diff with.
 109          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 110          * @param int $rcid Deprecated, no longer used!
 111          * @param bool $refreshCache If set, refreshes the diff cache
 112          * @param bool $unhide If set, allow viewing deleted revs
 113          */
 114         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 115                 $refreshCache = false, $unhide = false
 116         ) {
 117                 if ( $context instanceof IContextSource ) {
 118                         $this->setContext( $context );
 119                 }
 120
 121                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 122
 123                 $this->mOldid = $old;
 124                 $this->mNewid = $new;
 125                 $this->mRefreshCache = $refreshCache;
 126                 $this->unhide = $unhide;
 127         }
 128
 129         /**
 130          * @param bool $value
 131          */
 132         public function setReducedLineNumbers( $value = true ) {
 133                 $this->mReducedLineNumbers = $value;
 134         }
 135
 136         /**
 137          * @return Language
 138          */
 139         public function getDiffLang() {
 140                 if ( $this->mDiffLang === null ) {
 141                         # Default language in which the diff text is written.
 142                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 143                 }
 144
 145                 return $this->mDiffLang;
 146         }
 147
 148         /**
 149          * @return bool
 150          */
 151         public function wasCacheHit() {
 152                 return $this->mCacheHit;
 153         }
 154
 155         /**
 156          * @return int
 157          */
 158         public function getOldid() {
 159                 $this->loadRevisionIds();
 160
 161                 return $this->mOldid;
 162         }
 163
 164         /**
 165          * @return bool|int
 166          */
 167         public function getNewid() {
 168                 $this->loadRevisionIds();
 169
 170                 return $this->mNewid;
 171         }
 172
 173         /**
 174          * Look up a special:Undelete link to the given deleted revision id,
 175          * as a workaround for being unable to load deleted diffs in currently.
 176          *
 177          * @param int $id Revision ID
 178          *
 179          * @return string|bool Link HTML or false
 180          */
 181         public function deletedLink( $id ) {
 182                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 183                         $dbr = wfGetDB( DB_REPLICA );
 184                         $row = $dbr->selectRow( 'archive', '*',
 185                                 [ 'ar_rev_id' => $id ],
 186                                 __METHOD__ );
 187                         if ( $row ) {
 188                                 $rev = Revision::newFromArchiveRow( $row );
 189                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 190
 191                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
 192                                         'target' => $title->getPrefixedText(),
 193                                         'timestamp' => $rev->getTimestamp()
 194                                 ] );
 195                         }
 196                 }
 197
 198                 return false;
 199         }
 200
 201         /**
 202          * Build a wikitext link toward a deleted revision, if viewable.
 203          *
 204          * @param int $id Revision ID
 205          *
 206          * @return string Wikitext fragment
 207          */
 208         public function deletedIdMarker( $id ) {
 209                 $link = $this->deletedLink( $id );
 210                 if ( $link ) {
 211                         return "[$link $id]";
 212                 } else {
 213                         return (string)$id;
 214                 }
 215         }
 216
 217         private function showMissingRevision() {
 218                 $out = $this->getOutput();
 219
 220                 $missing = [];
 221                 if ( $this->mOldRev === null ||
 222                         ( $this->mOldRev && $this->mOldContent === null )
 223                 ) {
 224                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 225                 }
 226                 if ( $this->mNewRev === null ||
 227                         ( $this->mNewRev && $this->mNewContent === null )
 228                 ) {
 229                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 230                 }
 231
 232                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 233                 $msg = $this->msg( 'difference-missing-revision' )
 234                         ->params( $this->getLanguage()->listToText( $missing ) )
 235                         ->numParams( count( $missing ) )
 236                         ->parseAsBlock();
 237                 $out->addHTML( $msg );
 238         }
 239
 240         public function showDiffPage( $diffOnly = false ) {
 241                 # Allow frames except in certain special cases
 242                 $out = $this->getOutput();
 243                 $out->allowClickjacking();
 244                 $out->setRobotPolicy( 'noindex,nofollow' );
 245
 246                 // Allow extensions to add any extra output here
 247                 Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
 248
 249                 if ( !$this->loadRevisionData() ) {
 250                         if ( Hooks::run( 'DifferenceEngineShowDiffPageMaybeShowMissingRevision', [ $this ] ) ) {
 251                                 $this->showMissingRevision();
 252                         }
 253                         return;
 254                 }
 255
 256                 $user = $this->getUser();
 257                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 258                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 259                         $permErrors = wfMergeErrorArrays( $permErrors,
 260                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 261                 }
 262                 if ( count( $permErrors ) ) {
 263                         throw new PermissionsError( 'read', $permErrors );
 264                 }
 265
 266                 $rollback = '';
 267
 268                 $query = [];
 269                 # Carry over 'diffonly' param via navigation links
 270                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 271                         $query['diffonly'] = $diffOnly;
 272                 }
 273                 # Cascade unhide param in links for easy deletion browsing
 274                 if ( $this->unhide ) {
 275                         $query['unhide'] = 1;
 276                 }
 277
 278                 # Check if one of the revisions is deleted/suppressed
 279                 $deleted = $suppressed = false;
 280                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 281
 282                 $revisionTools = [];
 283
 284                 # mOldRev is false if the difference engine is called with a "vague" query for
 285                 # a diff between a version V and its previous version V' AND the version V
 286                 # is the first version of that article. In that case, V' does not exist.
 287                 if ( $this->mOldRev === false ) {
 288                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 289                         $samePage = true;
 290                         $oldHeader = '';
 291                         // Allow extensions to change the $oldHeader variable
 292                         Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
 293                 } else {
 294                         Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 295
 296                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 297                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 298                                 $samePage = true;
 299                         } else {
 300                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 301                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 302                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 303                                 $samePage = false;
 304                         }
 305
 306                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 307                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 308                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 309                                         if ( $rollbackLink ) {
 310                                                 $out->preventClickjacking();
 311                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 312                                         }
 313                                 }
 314
 315                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 316                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 317                                 ) {
 318                                         $undoLink = Html::element( 'a', [
 319                                                         'href' => $this->mNewPage->getLocalURL( [
 320                                                                 'action' => 'edit',
 321                                                                 'undoafter' => $this->mOldid,
 322                                                                 'undo' => $this->mNewid
 323                                                         ] ),
 324                                                         'title' => Linker::titleAttrib( 'undo' ),
 325                                                 ],
 326                                                 $this->msg( 'editundo' )->text()
 327                                         );
 328                                         $revisionTools['mw-diff-undo'] = $undoLink;
 329                                 }
 330                         }
 331
 332                         # Make "previous revision link"
 333                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 334                                 $prevlink = Linker::linkKnown(
 335                                         $this->mOldPage,
 336                                         $this->msg( 'previousdiff' )->escaped(),
 337                                         [ 'id' => 'differences-prevlink' ],
 338                                         [ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
 339                                 );
 340                         } else {
 341                                 $prevlink = '&#160;';
 342                         }
 343
 344                         if ( $this->mOldRev->isMinor() ) {
 345                                 $oldminor = ChangesList::flag( 'minor' );
 346                         } else {
 347                                 $oldminor = '';
 348                         }
 349
 350                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 351                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 352                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );
 353
 354                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 355                                 '<div id="mw-diff-otitle2">' .
 356                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 357                                 '<div id="mw-diff-otitle3">' . $oldminor .
 358                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 359                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 360                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 361
 362                         // Allow extensions to change the $oldHeader variable
 363                         Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
 364                                 $diffOnly, $ldel, $this->unhide ] );
 365
 366                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 367                                 $deleted = true; // old revisions text is hidden
 368                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 369                                         $suppressed = true; // also suppressed
 370                                 }
 371                         }
 372
 373                         # Check if this user can see the revisions
 374                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 375                                 $allowed = false;
 376                         }
 377                 }
 378
 379                 $out->addJsConfigVars( [
 380                         'wgDiffOldId' => $this->mOldid,
 381                         'wgDiffNewId' => $this->mNewid,
 382                 ] );
 383
 384                 # Make "next revision link"
 385                 # Skip next link on the top revision
 386                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 387                         $nextlink = Linker::linkKnown(
 388                                 $this->mNewPage,
 389                                 $this->msg( 'nextdiff' )->escaped(),
 390                                 [ 'id' => 'differences-nextlink' ],
 391                                 [ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
 392                         );
 393                 } else {
 394                         $nextlink = '&#160;';
 395                 }
 396
 397                 if ( $this->mNewRev->isMinor() ) {
 398                         $newminor = ChangesList::flag( 'minor' );
 399                 } else {
 400                         $newminor = '';
 401                 }
 402
 403                 # Handle RevisionDelete links...
 404                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 405
 406                 # Allow extensions to define their own revision tools
 407                 Hooks::run( 'DiffRevisionTools',
 408                         [ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
 409                 $formattedRevisionTools = [];
 410                 // Put each one in parentheses (poor man's button)
 411                 foreach ( $revisionTools as $key => $tool ) {
 412                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 413                         $element = Html::rawElement(
 414                                 'span',
 415                                 [ 'class' => $toolClass ],
 416                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 417                         );
 418                         $formattedRevisionTools[] = $element;
 419                 }
 420                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 421                         ' ' . implode( ' ', $formattedRevisionTools );
 422                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );
 423
 424                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 425                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 426                         " $rollback</div>" .
 427                         '<div id="mw-diff-ntitle3">' . $newminor .
 428                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 429                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 430                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 431
 432                 // Allow extensions to change the $newHeader variable
 433                 Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
 434                         $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
 435
 436                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 437                         $deleted = true; // new revisions text is hidden
 438                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 439                                 $suppressed = true; // also suppressed
 440                         }
 441                 }
 442
 443                 # If the diff cannot be shown due to a deleted revision, then output
 444                 # the diff header and links to unhide (if available)...
 445                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 446                         $this->showDiffStyle();
 447                         $multi = $this->getMultiNotice();
 448                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 449                         if ( !$allowed ) {
 450                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 451                                 # Give explanation for why revision is not visible
 452                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 453                                         [ $msg ] );
 454                         } else {
 455                                 # Give explanation and add a link to view the diff...
 456                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
 457                                 $link = $this->getTitle()->getFullURL( $query );
 458                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 459                                 $out->wrapWikiMsg(
 460                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 461                                         [ $msg, $link ]
 462                                 );
 463                         }
 464                 # Otherwise, output a regular diff...
 465                 } else {
 466                         # Add deletion notice if the user is viewing deleted content
 467                         $notice = '';
 468                         if ( $deleted ) {
 469                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 470                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 471                                         $this->msg( $msg )->parse() .
 472                                         "</div>\n";
 473                         }
 474                         $this->showDiff( $oldHeader, $newHeader, $notice );
 475                         if ( !$diffOnly ) {
 476                                 $this->renderNewRevision();
 477                         }
 478                 }
 479         }
 480
 481         /**
 482          * Build a link to mark a change as patrolled.
 483          *
 484          * Returns empty string if there's either no revision to patrol or the user is not allowed to.
 485          * Side effect: When the patrol link is build, this method will call
 486          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 487          *
 488          * @return string HTML or empty string
 489          */
 490         public function markPatrolledLink() {
 491                 if ( $this->mMarkPatrolledLink === null ) {
 492                         $linkInfo = $this->getMarkPatrolledLinkInfo();
 493                         // If false, there is no patrol link needed/allowed
 494                         if ( !$linkInfo ) {
 495                                 $this->mMarkPatrolledLink = '';
 496                         } else {
 497                                 $this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
 498                                         Linker::linkKnown(
 499                                                 $this->mNewPage,
 500                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 501                                                 [],
 502                                                 [
 503                                                         'action' => 'markpatrolled',
 504                                                         'rcid' => $linkInfo['rcid'],
 505                                                 ]
 506                                         ) . ']</span>';
 507                                 // Allow extensions to change the markpatrolled link
 508                                 Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
 509                                         &$this->mMarkPatrolledLink, $linkInfo['rcid'] ] );
 510                         }
 511                 }
 512                 return $this->mMarkPatrolledLink;
 513         }
 514
 515         /**
 516          * Returns an array of meta data needed to build a "mark as patrolled" link and
 517          * adds the mediawiki.page.patrol.ajax to the output.
 518          *
 519          * @return array|false An array of meta data for a patrol link (rcid only)
 520          *  or false if no link is needed
 521          */
 522         protected function getMarkPatrolledLinkInfo() {
 523                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 524
 525                 $user = $this->getUser();
 526
 527                 // Prepare a change patrol link, if applicable
 528                 if (
 529                         // Is patrolling enabled and the user allowed to?
 530                         $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 531                         // Only do this if the revision isn't more than 6 hours older
 532                         // than the Max RC age (6h because the RC might not be cleaned out regularly)
 533                         RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 534                 ) {
 535                         // Look for an unpatrolled change corresponding to this diff
 536                         $db = wfGetDB( DB_REPLICA );
 537                         $change = RecentChange::newFromConds(
 538                                 [
 539                                         'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 540                                         'rc_this_oldid' => $this->mNewid,
 541                                         'rc_patrolled' => 0
 542                                 ],
 543                                 __METHOD__
 544                         );
 545
 546                         if ( $change && !$change->getPerformer()->equals( $user ) ) {
 547                                 $rcid = $change->getAttribute( 'rc_id' );
 548                         } else {
 549                                 // None found or the page has been created by the current user.
 550                                 // If the user could patrol this it already would be patrolled
 551                                 $rcid = 0;
 552                         }
 553
 554                         // Allow extensions to possibly change the rcid here
 555                         // For example the rcid might be set to zero due to the user
 556                         // being the same as the performer of the change but an extension
 557                         // might still want to show it under certain conditions
 558                         Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
 559
 560                         // Build the link
 561                         if ( $rcid ) {
 562                                 $this->getOutput()->preventClickjacking();
 563                                 if ( $wgEnableAPI && $wgEnableWriteAPI
 564                                         && $user->isAllowed( 'writeapi' )
 565                                 ) {
 566                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 567                                 }
 568
 569                                 return [
 570                                         'rcid' => $rcid,
 571                                 ];
 572                         }
 573                 }
 574
 575                 // No mark as patrolled link applicable
 576                 return false;
 577         }
 578
 579         /**
 580          * @param Revision $rev
 581          *
 582          * @return string
 583          */
 584         protected function revisionDeleteLink( $rev ) {
 585                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 586                 if ( $link !== '' ) {
 587                         $link = '&#160;&#160;&#160;' . $link . ' ';
 588                 }
 589
 590                 return $link;
 591         }
 592
 593         /**
 594          * Show the new revision of the page.
 595          */
 596         public function renderNewRevision() {
 597                 $out = $this->getOutput();
 598                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 599                 # Add "current version as of X" title
 600                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 601                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 602                 # Page content may be handled by a hooked call instead...
 603                 # @codingStandardsIgnoreStart Ignoring long lines.
 604                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 605                         $this->loadNewText();
 606                         $out->setRevisionId( $this->mNewid );
 607                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 608                         $out->setArticleFlag( true );
 609
 610                         if ( !Hooks::run( 'ArticleContentViewCustom', [ $this->mNewContent, $this->mNewPage, $out ] ) ) {
 611                                 // Handled by extension
 612                         } else {
 613                                 // Normal page
 614                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 615                                         // If the Title stored in the context is the same as the one
 616                                         // of the new revision, we can use its associated WikiPage
 617                                         // object.
 618                                         $wikiPage = $this->getWikiPage();
 619                                 } else {
 620                                         // Otherwise we need to create our own WikiPage object
 621                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 622                                 }
 623
 624                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 625
 626                                 # WikiPage::getParserOutput() should not return false, but just in case
 627                                 if ( $parserOutput ) {
 628                                         // Allow extensions to change parser output here
 629                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput', [ $this, $out, $parserOutput, $wikiPage ] ) ) {
 630                                                 $out->addParserOutput( $parserOutput );
 631                                         }
 632                                 }
 633                         }
 634                 }
 635                 # @codingStandardsIgnoreEnd
 636
 637                 // Allow extensions to optionally not show the final patrolled link
 638                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 639                         # Add redundant patrol link on bottom...
 640                         $out->addHTML( $this->markPatrolledLink() );
 641                 }
 642         }
 643
 644         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 645                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 646
 647                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 648                         $parserOptions->setEditSection( false );
 649                 }
 650
 651                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 652
 653                 return $parserOutput;
 654         }
 655
 656         /**
 657          * Get the diff text, send it to the OutputPage object
 658          * Returns false if the diff could not be generated, otherwise returns true
 659          *
 660          * @param string|bool $otitle Header for old text or false
 661          * @param string|bool $ntitle Header for new text or false
 662          * @param string $notice HTML between diff header and body
 663          *
 664          * @return bool
 665          */
 666         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 667                 // Allow extensions to affect the output here
 668                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 669
 670                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 671                 if ( $diff === false ) {
 672                         $this->showMissingRevision();
 673
 674                         return false;
 675                 } else {
 676                         $this->showDiffStyle();
 677                         $this->getOutput()->addHTML( $diff );
 678
 679                         return true;
 680                 }
 681         }
 682
 683         /**
 684          * Add style sheets for diff display.
 685          */
 686         public function showDiffStyle() {
 687                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 688         }
 689
 690         /**
 691          * Get complete diff table, including header
 692          *
 693          * @param string|bool $otitle Header for old text or false
 694          * @param string|bool $ntitle Header for new text or false
 695          * @param string $notice HTML between diff header and body
 696          *
 697          * @return mixed
 698          */
 699         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 700                 $body = $this->getDiffBody();
 701                 if ( $body === false ) {
 702                         return false;
 703                 }
 704
 705                 $multi = $this->getMultiNotice();
 706                 // Display a message when the diff is empty
 707                 if ( $body === '' ) {
 708                         $notice .= '<div class="mw-diff-empty">' .
 709                                 $this->msg( 'diff-empty' )->parse() .
 710                                 "</div>\n";
 711                 }
 712
 713                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 714         }
 715
 716         /**
 717          * Get the diff table body, without header
 718          *
 719          * @return mixed (string/false)
 720          */
 721         public function getDiffBody() {
 722                 $this->mCacheHit = true;
 723                 // Check if the diff should be hidden from this user
 724                 if ( !$this->loadRevisionData() ) {
 725                         return false;
 726                 } elseif ( $this->mOldRev &&
 727                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 728                 ) {
 729                         return false;
 730                 } elseif ( $this->mNewRev &&
 731                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 732                 ) {
 733                         return false;
 734                 }
 735                 // Short-circuit
 736                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 737                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 738                 ) {
 739                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 740                                 return '';
 741                         }
 742                 }
 743                 // Cacheable?
 744                 $key = false;
 745                 $cache = ObjectCache::getMainWANInstance();
 746                 if ( $this->mOldid && $this->mNewid ) {
 747                         $key = $this->getDiffBodyCacheKey();
 748
 749                         // Try cache
 750                         if ( !$this->mRefreshCache ) {
 751                                 $difftext = $cache->get( $key );
 752                                 if ( $difftext ) {
 753                                         wfIncrStats( 'diff_cache.hit' );
 754                                         $difftext = $this->localiseLineNumbers( $difftext );
 755                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 756
 757                                         return $difftext;
 758                                 }
 759                         } // don't try to load but save the result
 760                 }
 761                 $this->mCacheHit = false;
 762
 763                 // Loadtext is permission safe, this just clears out the diff
 764                 if ( !$this->loadText() ) {
 765                         return false;
 766                 }
 767
 768                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 769
 770                 // Avoid PHP 7.1 warning from passing $this by reference
 771                 $diffEngine = $this;
 772
 773                 // Save to cache for 7 days
 774                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 775                         wfIncrStats( 'diff_cache.uncacheable' );
 776                 } elseif ( $key !== false && $difftext !== false ) {
 777                         wfIncrStats( 'diff_cache.miss' );
 778                         $cache->set( $key, $difftext, 7 * 86400 );
 779                 } else {
 780                         wfIncrStats( 'diff_cache.uncacheable' );
 781                 }
 782                 // Replace line numbers with the text in the user's language
 783                 if ( $difftext !== false ) {
 784                         $difftext = $this->localiseLineNumbers( $difftext );
 785                 }
 786
 787                 return $difftext;
 788         }
 789
 790         /**
 791          * Returns the cache key for diff body text or content.
 792          *
 793          * @since 1.23
 794          *
 795          * @throws MWException
 796          * @return string
 797          */
 798         protected function getDiffBodyCacheKey() {
 799                 if ( !$this->mOldid || !$this->mNewid ) {
 800                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 801                 }
 802
 803                 return wfMemcKey( 'diff', 'version', self::DIFF_VERSION,
 804                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 805         }
 806
 807         /**
 808          * Generate a diff, no caching.
 809          *
 810          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 811          * serialization of the given Content objects. This will fail if $old or $new are not
 812          * instances of TextContent.
 813          *
 814          * Subclasses may override this to provide a different rendering for the diff,
 815          * perhaps taking advantage of the content's native form. This is required for all content
 816          * models that are not text based.
 817          *
 818          * @since 1.21
 819          *
 820          * @param Content $old Old content
 821          * @param Content $new New content
 822          *
 823          * @throws MWException If old or new content is not an instance of TextContent.
 824          * @return bool|string
 825          */
 826         public function generateContentDiffBody( Content $old, Content $new ) {
 827                 if ( !( $old instanceof TextContent ) ) {
 828                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 829                                 "override generateContentDiffBody to fix this." );
 830                 }
 831
 832                 if ( !( $new instanceof TextContent ) ) {
 833                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 834                                 . "override generateContentDiffBody to fix this." );
 835                 }
 836
 837                 $otext = $old->serialize();
 838                 $ntext = $new->serialize();
 839
 840                 return $this->generateTextDiffBody( $otext, $ntext );
 841         }
 842
 843         /**
 844          * Generate a diff, no caching
 845          *
 846          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 847          *
 848          * @param string $otext Old text, must be already segmented
 849          * @param string $ntext New text, must be already segmented
 850          *
 851          * @return bool|string
 852          */
 853         public function generateTextDiffBody( $otext, $ntext ) {
 854                 $diff = function () use ( $otext, $ntext ) {
 855                         $time = microtime( true );
 856
 857                         $result = $this->textDiff( $otext, $ntext );
 858
 859                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 860                         MediaWikiServices::getInstance()->getStatsdDataFactory()->timing( 'diff_time', $time );
 861                         // Log requests slower than 99th percentile
 862                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 863                                 wfDebugLog( 'diff',
 864                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 865                         }
 866
 867                         return $result;
 868                 };
 869
 870                 /**
 871                  * @param Status $status
 872                  * @throws FatalError
 873                  */
 874                 $error = function ( $status ) {
 875                         throw new FatalError( $status->getWikiText() );
 876                 };
 877
 878                 // Use PoolCounter if the diff looks like it can be expensive
 879                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 880                         $work = new PoolCounterWorkViaCallback( 'diff',
 881                                 md5( $otext ) . md5( $ntext ),
 882                                 [ 'doWork' => $diff, 'error' => $error ]
 883                         );
 884                         return $work->execute();
 885                 }
 886
 887                 return $diff();
 888         }
 889
 890         /**
 891          * Generates diff, to be wrapped internally in a logging/instrumentation
 892          *
 893          * @param string $otext Old text, must be already segmented
 894          * @param string $ntext New text, must be already segmented
 895          * @return bool|string
 896          */
 897         protected function textDiff( $otext, $ntext ) {
 898                 global $wgExternalDiffEngine, $wgContLang;
 899
 900                 $otext = str_replace( "\r\n", "\n", $otext );
 901                 $ntext = str_replace( "\r\n", "\n", $ntext );
 902
 903                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 904                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 905                         $wgExternalDiffEngine = false;
 906                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 907                         // Same as above, but with no deprecation warnings
 908                         $wgExternalDiffEngine = false;
 909                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 910                         // And prevent people from shooting themselves in the foot...
 911                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 912                         $wgExternalDiffEngine = false;
 913                 }
 914
 915                 // Better external diff engine, the 2 may some day be dropped
 916                 // This one does the escaping and segmenting itself
 917                 if ( function_exists( 'wikidiff2_do_diff' ) && $wgExternalDiffEngine === false ) {
 918                         $wikidiff2Version = phpversion( 'wikidiff2' );
 919                         if (
 920                                 $wikidiff2Version !== false &&
 921                                 version_compare( $wikidiff2Version, '0.3.0', '>=' )
 922                         ) {
 923                                 $text = wikidiff2_do_diff(
 924                                         $otext,
 925                                         $ntext,
 926                                         2,
 927                                         $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' )
 928                                 );
 929                         } else {
 930                                 // Don't pass the 4th parameter for compatibility with older versions of wikidiff2
 931                                 $text = wikidiff2_do_diff(
 932                                         $otext,
 933                                         $ntext,
 934                                         2
 935                                 );
 936
 937                                 // Log a warning in case the configuration value is set to not silently ignore it
 938                                 if ( $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' ) > 0 ) {
 939                                         wfLogWarning( '$wgWikiDiff2MovedParagraphDetectionCutoff is set but has no
 940                                                 effect since the used version of WikiDiff2 does not support it.' );
 941                                 }
 942                         }
 943
 944                         $text .= $this->debug( 'wikidiff2' );
 945
 946                         return $text;
 947                 } elseif ( $wgExternalDiffEngine !== false && is_executable( $wgExternalDiffEngine ) ) {
 948                         # Diff via the shell
 949                         $tmpDir = wfTempDir();
 950                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 951                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 952
 953                         $tempFile1 = fopen( $tempName1, "w" );
 954                         if ( !$tempFile1 ) {
 955                                 return false;
 956                         }
 957                         $tempFile2 = fopen( $tempName2, "w" );
 958                         if ( !$tempFile2 ) {
 959                                 return false;
 960                         }
 961                         fwrite( $tempFile1, $otext );
 962                         fwrite( $tempFile2, $ntext );
 963                         fclose( $tempFile1 );
 964                         fclose( $tempFile2 );
 965                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 966                         $difftext = wfShellExec( $cmd );
 967                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 968                         unlink( $tempName1 );
 969                         unlink( $tempName2 );
 970
 971                         return $difftext;
 972                 }
 973
 974                 # Native PHP diff
 975                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 976                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 977                 $diffs = new Diff( $ota, $nta );
 978                 $formatter = new TableDiffFormatter();
 979                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 980
 981                 return $difftext;
 982         }
 983
 984         /**
 985          * Generate a debug comment indicating diff generating time,
 986          * server node, and generator backend.
 987          *
 988          * @param string $generator : What diff engine was used
 989          *
 990          * @return string
 991          */
 992         protected function debug( $generator = "internal" ) {
 993                 global $wgShowHostnames;
 994                 if ( !$this->enableDebugComment ) {
 995                         return '';
 996                 }
 997                 $data = [ $generator ];
 998                 if ( $wgShowHostnames ) {
 999                         $data[] = wfHostname();
1000                 }
1001                 $data[] = wfTimestamp( TS_DB );
1002
1003                 return "<!-- diff generator: " .
1004                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1005                         " -->\n";
1006         }
1007
1008         /**
1009          * Replace line numbers with the text in the user's language
1010          *
1011          * @param string $text
1012          *
1013          * @return mixed
1014          */
1015         public function localiseLineNumbers( $text ) {
1016                 return preg_replace_callback(
1017                         '/<!--LINE (\d+)-->/',
1018                         [ $this, 'localiseLineNumbersCb' ],
1019                         $text
1020                 );
1021         }
1022
1023         public function localiseLineNumbersCb( $matches ) {
1024                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1025                         return '';
1026                 }
1027
1028                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1029         }
1030
1031         /**
1032          * If there are revisions between the ones being compared, return a note saying so.
1033          *
1034          * @return string
1035          */
1036         public function getMultiNotice() {
1037                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1038                         return '';
1039                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1040                         // Comparing two different pages? Count would be meaningless.
1041                         return '';
1042                 }
1043
1044                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1045                         $oldRev = $this->mNewRev; // flip
1046                         $newRev = $this->mOldRev; // flip
1047                 } else { // normal case
1048                         $oldRev = $this->mOldRev;
1049                         $newRev = $this->mNewRev;
1050                 }
1051
1052                 // Sanity: don't show the notice if too many rows must be scanned
1053                 // @todo show some special message for that case
1054                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1055                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1056                         $limit = 100; // use diff-multi-manyusers if too many users
1057                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1058                         $numUsers = count( $users );
1059
1060                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1061                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1062                         }
1063
1064                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1065                 }
1066
1067                 return ''; // nothing
1068         }
1069
1070         /**
1071          * Get a notice about how many intermediate edits and users there are
1072          *
1073          * @param int $numEdits
1074          * @param int $numUsers
1075          * @param int $limit
1076          *
1077          * @return string
1078          */
1079         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1080                 if ( $numUsers === 0 ) {
1081                         $msg = 'diff-multi-sameuser';
1082                 } elseif ( $numUsers > $limit ) {
1083                         $msg = 'diff-multi-manyusers';
1084                         $numUsers = $limit;
1085                 } else {
1086                         $msg = 'diff-multi-otherusers';
1087                 }
1088
1089                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1090         }
1091
1092         /**
1093          * Get a header for a specified revision.
1094          *
1095          * @param Revision $rev
1096          * @param string $complete 'complete' to get the header wrapped depending
1097          *        the visibility of the revision and a link to edit the page.
1098          *
1099          * @return string HTML fragment
1100          */
1101         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1102                 $lang = $this->getLanguage();
1103                 $user = $this->getUser();
1104                 $revtimestamp = $rev->getTimestamp();
1105                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1106                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1107                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1108
1109                 $header = $this->msg(
1110                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1111                         $timestamp,
1112                         $dateofrev,
1113                         $timeofrev
1114                 )->escaped();
1115
1116                 if ( $complete !== 'complete' ) {
1117                         return $header;
1118                 }
1119
1120                 $title = $rev->getTitle();
1121
1122                 $header = Linker::linkKnown( $title, $header, [],
1123                         [ 'oldid' => $rev->getId() ] );
1124
1125                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1126                         $editQuery = [ 'action' => 'edit' ];
1127                         if ( !$rev->isCurrent() ) {
1128                                 $editQuery['oldid'] = $rev->getId();
1129                         }
1130
1131                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1132                         $msg = $this->msg( $key )->escaped();
1133                         $editLink = $this->msg( 'parentheses' )->rawParams(
1134                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1135                         $header .= ' ' . Html::rawElement(
1136                                 'span',
1137                                 [ 'class' => 'mw-diff-edit' ],
1138                                 $editLink
1139                         );
1140                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1141                                 $header = Html::rawElement(
1142                                         'span',
1143                                         [ 'class' => 'history-deleted' ],
1144                                         $header
1145                                 );
1146                         }
1147                 } else {
1148                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1149                 }
1150
1151                 return $header;
1152         }
1153
1154         /**
1155          * Add the header to a diff body
1156          *
1157          * @param string $diff Diff body
1158          * @param string $otitle Old revision header
1159          * @param string $ntitle New revision header
1160          * @param string $multi Notice telling user that there are intermediate
1161          *   revisions between the ones being compared
1162          * @param string $notice Other notices, e.g. that user is viewing deleted content
1163          *
1164          * @return string
1165          */
1166         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1167                 // shared.css sets diff in interface language/dir, but the actual content
1168                 // is often in a different language, mostly the page content language/dir
1169                 $header = Html::openElement( 'table', [
1170                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1171                         'data-mw' => 'interface',
1172                 ] );
1173                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1174
1175                 if ( !$diff && !$otitle ) {
1176                         $header .= "
1177                         <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1178                         <td class=\"diff-ntitle\">{$ntitle}</td>
1179                         </tr>";
1180                         $multiColspan = 1;
1181                 } else {
1182                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1183                                 $header .= "
1184                                 <col class=\"diff-marker\" />
1185                                 <col class=\"diff-content\" />
1186                                 <col class=\"diff-marker\" />
1187                                 <col class=\"diff-content\" />";
1188                                 $colspan = 2;
1189                                 $multiColspan = 4;
1190                         } else {
1191                                 $colspan = 1;
1192                                 $multiColspan = 2;
1193                         }
1194                         if ( $otitle || $ntitle ) {
1195                                 $header .= "
1196                                 <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1197                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1198                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1199                                 </tr>";
1200                         }
1201                 }
1202
1203                 if ( $multi != '' ) {
1204                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1205                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1206                 }
1207                 if ( $notice != '' ) {
1208                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1209                                 "lang=\"{$userLang}\">{$notice}</td></tr>";
1210                 }
1211
1212                 return $header . $diff . "</table>";
1213         }
1214
1215         /**
1216          * Use specified text instead of loading from the database
1217          * @param Content $oldContent
1218          * @param Content $newContent
1219          * @since 1.21
1220          */
1221         public function setContent( Content $oldContent, Content $newContent ) {
1222                 $this->mOldContent = $oldContent;
1223                 $this->mNewContent = $newContent;
1224
1225                 $this->mTextLoaded = 2;
1226                 $this->mRevisionsLoaded = true;
1227         }
1228
1229         /**
1230          * Set the language in which the diff text is written
1231          * (Defaults to page content language).
1232          * @param Language|string $lang
1233          * @since 1.19
1234          */
1235         public function setTextLanguage( $lang ) {
1236                 $this->mDiffLang = wfGetLangObj( $lang );
1237         }
1238
1239         /**
1240          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1241          * to a pair of actual integers representing revision ids.
1242          *
1243          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1244          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1245          *
1246          * @return int[] List of two revision ids, older first, later second.
1247          *     Zero signifies invalid argument passed.
1248          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1249          */
1250         public function mapDiffPrevNext( $old, $new ) {
1251                 if ( $new === 'prev' ) {
1252                         // Show diff between revision $old and the previous one. Get previous one from DB.
1253                         $newid = intval( $old );
1254                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1255                 } elseif ( $new === 'next' ) {
1256                         // Show diff between revision $old and the next one. Get next one from DB.
1257                         $oldid = intval( $old );
1258                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1259                 } else {
1260                         $oldid = intval( $old );
1261                         $newid = intval( $new );
1262                 }
1263
1264                 return [ $oldid, $newid ];
1265         }
1266
1267         /**
1268          * Load revision IDs
1269          */
1270         private function loadRevisionIds() {
1271                 if ( $this->mRevisionsIdsLoaded ) {
1272                         return;
1273                 }
1274
1275                 $this->mRevisionsIdsLoaded = true;
1276
1277                 $old = $this->mOldid;
1278                 $new = $this->mNewid;
1279
1280                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1281                 if ( $new === 'next' && $this->mNewid === false ) {
1282                         # if no result, NewId points to the newest old revision. The only newer
1283                         # revision is cur, which is "0".
1284                         $this->mNewid = 0;
1285                 }
1286
1287                 Hooks::run(
1288                         'NewDifferenceEngine',
1289                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1290                 );
1291         }
1292
1293         /**
1294          * Load revision metadata for the specified articles. If newid is 0, then compare
1295          * the old article in oldid to the current article; if oldid is 0, then
1296          * compare the current article to the immediately previous one (ignoring the
1297          * value of newid).
1298          *
1299          * If oldid is false, leave the corresponding revision object set
1300          * to false. This is impossible via ordinary user input, and is provided for
1301          * API convenience.
1302          *
1303          * @return bool
1304          */
1305         public function loadRevisionData() {
1306                 if ( $this->mRevisionsLoaded ) {
1307                         return true;
1308                 }
1309
1310                 // Whether it succeeds or fails, we don't want to try again
1311                 $this->mRevisionsLoaded = true;
1312
1313                 $this->loadRevisionIds();
1314
1315                 // Load the new revision object
1316                 if ( $this->mNewid ) {
1317                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1318                 } else {
1319                         $this->mNewRev = Revision::newFromTitle(
1320                                 $this->getTitle(),
1321                                 false,
1322                                 Revision::READ_NORMAL
1323                         );
1324                 }
1325
1326                 if ( !$this->mNewRev instanceof Revision ) {
1327                         return false;
1328                 }
1329
1330                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1331                 $this->mNewid = $this->mNewRev->getId();
1332                 $this->mNewPage = $this->mNewRev->getTitle();
1333
1334                 // Load the old revision object
1335                 $this->mOldRev = false;
1336                 if ( $this->mOldid ) {
1337                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1338                 } elseif ( $this->mOldid === 0 ) {
1339                         $rev = $this->mNewRev->getPrevious();
1340                         if ( $rev ) {
1341                                 $this->mOldid = $rev->getId();
1342                                 $this->mOldRev = $rev;
1343                         } else {
1344                                 // No previous revision; mark to show as first-version only.
1345                                 $this->mOldid = false;
1346                                 $this->mOldRev = false;
1347                         }
1348                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1349
1350                 if ( is_null( $this->mOldRev ) ) {
1351                         return false;
1352                 }
1353
1354                 if ( $this->mOldRev ) {
1355                         $this->mOldPage = $this->mOldRev->getTitle();
1356                 }
1357
1358                 // Load tags information for both revisions
1359                 $dbr = wfGetDB( DB_REPLICA );
1360                 if ( $this->mOldid !== false ) {
1361                         $this->mOldTags = $dbr->selectField(
1362                                 'tag_summary',
1363                                 'ts_tags',
1364                                 [ 'ts_rev_id' => $this->mOldid ],
1365                                 __METHOD__
1366                         );
1367                 } else {
1368                         $this->mOldTags = false;
1369                 }
1370                 $this->mNewTags = $dbr->selectField(
1371                         'tag_summary',
1372                         'ts_tags',
1373                         [ 'ts_rev_id' => $this->mNewid ],
1374                         __METHOD__
1375                 );
1376
1377                 return true;
1378         }
1379
1380         /**
1381          * Load the text of the revisions, as well as revision data.
1382          *
1383          * @return bool
1384          */
1385         public function loadText() {
1386                 if ( $this->mTextLoaded == 2 ) {
1387                         return true;
1388                 }
1389
1390                 // Whether it succeeds or fails, we don't want to try again
1391                 $this->mTextLoaded = 2;
1392
1393                 if ( !$this->loadRevisionData() ) {
1394                         return false;
1395                 }
1396
1397                 if ( $this->mOldRev ) {
1398                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1399                         if ( $this->mOldContent === null ) {
1400                                 return false;
1401                         }
1402                 }
1403
1404                 if ( $this->mNewRev ) {
1405                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1406                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1407                         if ( $this->mNewContent === null ) {
1408                                 return false;
1409                         }
1410                 }
1411
1412                 return true;
1413         }
1414
1415         /**
1416          * Load the text of the new revision, not the old one
1417          *
1418          * @return bool
1419          */
1420         public function loadNewText() {
1421                 if ( $this->mTextLoaded >= 1 ) {
1422                         return true;
1423                 }
1424
1425                 $this->mTextLoaded = 1;
1426
1427                 if ( !$this->loadRevisionData() ) {
1428                         return false;
1429                 }
1430
1431                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1432
1433                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1434
1435                 return true;
1436         }
1437
1438 }