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                                 Revision::selectArchiveFields(),
 186                                 [ 'ar_rev_id' => $id ],
 187                                 __METHOD__ );
 188                         if ( $row ) {
 189                                 $rev = Revision::newFromArchiveRow( $row );
 190                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 191
 192                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
 193                                         'target' => $title->getPrefixedText(),
 194                                         'timestamp' => $rev->getTimestamp()
 195                                 ] );
 196                         }
 197                 }
 198
 199                 return false;
 200         }
 201
 202         /**
 203          * Build a wikitext link toward a deleted revision, if viewable.
 204          *
 205          * @param int $id Revision ID
 206          *
 207          * @return string Wikitext fragment
 208          */
 209         public function deletedIdMarker( $id ) {
 210                 $link = $this->deletedLink( $id );
 211                 if ( $link ) {
 212                         return "[$link $id]";
 213                 } else {
 214                         return (string)$id;
 215                 }
 216         }
 217
 218         private function showMissingRevision() {
 219                 $out = $this->getOutput();
 220
 221                 $missing = [];
 222                 if ( $this->mOldRev === null ||
 223                         ( $this->mOldRev && $this->mOldContent === null )
 224                 ) {
 225                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 226                 }
 227                 if ( $this->mNewRev === null ||
 228                         ( $this->mNewRev && $this->mNewContent === null )
 229                 ) {
 230                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 231                 }
 232
 233                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 234                 $msg = $this->msg( 'difference-missing-revision' )
 235                         ->params( $this->getLanguage()->listToText( $missing ) )
 236                         ->numParams( count( $missing ) )
 237                         ->parseAsBlock();
 238                 $out->addHTML( $msg );
 239         }
 240
 241         public function showDiffPage( $diffOnly = false ) {
 242                 # Allow frames except in certain special cases
 243                 $out = $this->getOutput();
 244                 $out->allowClickjacking();
 245                 $out->setRobotPolicy( 'noindex,nofollow' );
 246
 247                 // Allow extensions to add any extra output here
 248                 Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
 249
 250                 if ( !$this->loadRevisionData() ) {
 251                         if ( Hooks::run( 'DifferenceEngineShowDiffPageMaybeShowMissingRevision', [ $this ] ) ) {
 252                                 $this->showMissingRevision();
 253                         }
 254                         return;
 255                 }
 256
 257                 $user = $this->getUser();
 258                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 259                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 260                         $permErrors = wfMergeErrorArrays( $permErrors,
 261                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 262                 }
 263                 if ( count( $permErrors ) ) {
 264                         throw new PermissionsError( 'read', $permErrors );
 265                 }
 266
 267                 $rollback = '';
 268
 269                 $query = [];
 270                 # Carry over 'diffonly' param via navigation links
 271                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 272                         $query['diffonly'] = $diffOnly;
 273                 }
 274                 # Cascade unhide param in links for easy deletion browsing
 275                 if ( $this->unhide ) {
 276                         $query['unhide'] = 1;
 277                 }
 278
 279                 # Check if one of the revisions is deleted/suppressed
 280                 $deleted = $suppressed = false;
 281                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 282
 283                 $revisionTools = [];
 284
 285                 # mOldRev is false if the difference engine is called with a "vague" query for
 286                 # a diff between a version V and its previous version V' AND the version V
 287                 # is the first version of that article. In that case, V' does not exist.
 288                 if ( $this->mOldRev === false ) {
 289                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 290                         $samePage = true;
 291                         $oldHeader = '';
 292                         // Allow extensions to change the $oldHeader variable
 293                         Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
 294                 } else {
 295                         Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 296
 297                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 298                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 299                                 $samePage = true;
 300                         } else {
 301                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 302                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 303                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 304                                 $samePage = false;
 305                         }
 306
 307                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 308                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 309                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 310                                         if ( $rollbackLink ) {
 311                                                 $out->preventClickjacking();
 312                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 313                                         }
 314                                 }
 315
 316                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 317                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 318                                 ) {
 319                                         $undoLink = Html::element( 'a', [
 320                                                         'href' => $this->mNewPage->getLocalURL( [
 321                                                                 'action' => 'edit',
 322                                                                 'undoafter' => $this->mOldid,
 323                                                                 'undo' => $this->mNewid
 324                                                         ] ),
 325                                                         'title' => Linker::titleAttrib( 'undo' ),
 326                                                 ],
 327                                                 $this->msg( 'editundo' )->text()
 328                                         );
 329                                         $revisionTools['mw-diff-undo'] = $undoLink;
 330                                 }
 331                         }
 332
 333                         # Make "previous revision link"
 334                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 335                                 $prevlink = Linker::linkKnown(
 336                                         $this->mOldPage,
 337                                         $this->msg( 'previousdiff' )->escaped(),
 338                                         [ 'id' => 'differences-prevlink' ],
 339                                         [ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
 340                                 );
 341                         } else {
 342                                 $prevlink = '&#160;';
 343                         }
 344
 345                         if ( $this->mOldRev->isMinor() ) {
 346                                 $oldminor = ChangesList::flag( 'minor' );
 347                         } else {
 348                                 $oldminor = '';
 349                         }
 350
 351                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 352                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 353                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );
 354
 355                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 356                                 '<div id="mw-diff-otitle2">' .
 357                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 358                                 '<div id="mw-diff-otitle3">' . $oldminor .
 359                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 360                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 361                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 362
 363                         // Allow extensions to change the $oldHeader variable
 364                         Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
 365                                 $diffOnly, $ldel, $this->unhide ] );
 366
 367                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 368                                 $deleted = true; // old revisions text is hidden
 369                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 370                                         $suppressed = true; // also suppressed
 371                                 }
 372                         }
 373
 374                         # Check if this user can see the revisions
 375                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 376                                 $allowed = false;
 377                         }
 378                 }
 379
 380                 $out->addJsConfigVars( [
 381                         'wgDiffOldId' => $this->mOldid,
 382                         'wgDiffNewId' => $this->mNewid,
 383                 ] );
 384
 385                 # Make "next revision link"
 386                 # Skip next link on the top revision
 387                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 388                         $nextlink = Linker::linkKnown(
 389                                 $this->mNewPage,
 390                                 $this->msg( 'nextdiff' )->escaped(),
 391                                 [ 'id' => 'differences-nextlink' ],
 392                                 [ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
 393                         );
 394                 } else {
 395                         $nextlink = '&#160;';
 396                 }
 397
 398                 if ( $this->mNewRev->isMinor() ) {
 399                         $newminor = ChangesList::flag( 'minor' );
 400                 } else {
 401                         $newminor = '';
 402                 }
 403
 404                 # Handle RevisionDelete links...
 405                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 406
 407                 # Allow extensions to define their own revision tools
 408                 Hooks::run( 'DiffRevisionTools',
 409                         [ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
 410                 $formattedRevisionTools = [];
 411                 // Put each one in parentheses (poor man's button)
 412                 foreach ( $revisionTools as $key => $tool ) {
 413                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 414                         $element = Html::rawElement(
 415                                 'span',
 416                                 [ 'class' => $toolClass ],
 417                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 418                         );
 419                         $formattedRevisionTools[] = $element;
 420                 }
 421                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 422                         ' ' . implode( ' ', $formattedRevisionTools );
 423                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );
 424
 425                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 426                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 427                         " $rollback</div>" .
 428                         '<div id="mw-diff-ntitle3">' . $newminor .
 429                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 430                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 431                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 432
 433                 // Allow extensions to change the $newHeader variable
 434                 Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
 435                         $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
 436
 437                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 438                         $deleted = true; // new revisions text is hidden
 439                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 440                                 $suppressed = true; // also suppressed
 441                         }
 442                 }
 443
 444                 # If the diff cannot be shown due to a deleted revision, then output
 445                 # the diff header and links to unhide (if available)...
 446                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 447                         $this->showDiffStyle();
 448                         $multi = $this->getMultiNotice();
 449                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 450                         if ( !$allowed ) {
 451                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 452                                 # Give explanation for why revision is not visible
 453                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 454                                         [ $msg ] );
 455                         } else {
 456                                 # Give explanation and add a link to view the diff...
 457                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
 458                                 $link = $this->getTitle()->getFullURL( $query );
 459                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 460                                 $out->wrapWikiMsg(
 461                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 462                                         [ $msg, $link ]
 463                                 );
 464                         }
 465                 # Otherwise, output a regular diff...
 466                 } else {
 467                         # Add deletion notice if the user is viewing deleted content
 468                         $notice = '';
 469                         if ( $deleted ) {
 470                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 471                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 472                                         $this->msg( $msg )->parse() .
 473                                         "</div>\n";
 474                         }
 475                         $this->showDiff( $oldHeader, $newHeader, $notice );
 476                         if ( !$diffOnly ) {
 477                                 $this->renderNewRevision();
 478                         }
 479                 }
 480         }
 481
 482         /**
 483          * Build a link to mark a change as patrolled.
 484          *
 485          * Returns empty string if there's either no revision to patrol or the user is not allowed to.
 486          * Side effect: When the patrol link is build, this method will call
 487          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 488          *
 489          * @return string HTML or empty string
 490          */
 491         public function markPatrolledLink() {
 492                 if ( $this->mMarkPatrolledLink === null ) {
 493                         $linkInfo = $this->getMarkPatrolledLinkInfo();
 494                         // If false, there is no patrol link needed/allowed
 495                         if ( !$linkInfo ) {
 496                                 $this->mMarkPatrolledLink = '';
 497                         } else {
 498                                 $this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
 499                                         Linker::linkKnown(
 500                                                 $this->mNewPage,
 501                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 502                                                 [],
 503                                                 [
 504                                                         'action' => 'markpatrolled',
 505                                                         'rcid' => $linkInfo['rcid'],
 506                                                 ]
 507                                         ) . ']</span>';
 508                                 // Allow extensions to change the markpatrolled link
 509                                 Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
 510                                         &$this->mMarkPatrolledLink, $linkInfo['rcid'] ] );
 511                         }
 512                 }
 513                 return $this->mMarkPatrolledLink;
 514         }
 515
 516         /**
 517          * Returns an array of meta data needed to build a "mark as patrolled" link and
 518          * adds the mediawiki.page.patrol.ajax to the output.
 519          *
 520          * @return array|false An array of meta data for a patrol link (rcid only)
 521          *  or false if no link is needed
 522          */
 523         protected function getMarkPatrolledLinkInfo() {
 524                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 525
 526                 $user = $this->getUser();
 527
 528                 // Prepare a change patrol link, if applicable
 529                 if (
 530                         // Is patrolling enabled and the user allowed to?
 531                         $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 532                         // Only do this if the revision isn't more than 6 hours older
 533                         // than the Max RC age (6h because the RC might not be cleaned out regularly)
 534                         RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 535                 ) {
 536                         // Look for an unpatrolled change corresponding to this diff
 537                         $db = wfGetDB( DB_REPLICA );
 538                         $change = RecentChange::newFromConds(
 539                                 [
 540                                         'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 541                                         'rc_this_oldid' => $this->mNewid,
 542                                         'rc_patrolled' => 0
 543                                 ],
 544                                 __METHOD__
 545                         );
 546
 547                         if ( $change && !$change->getPerformer()->equals( $user ) ) {
 548                                 $rcid = $change->getAttribute( 'rc_id' );
 549                         } else {
 550                                 // None found or the page has been created by the current user.
 551                                 // If the user could patrol this it already would be patrolled
 552                                 $rcid = 0;
 553                         }
 554
 555                         // Allow extensions to possibly change the rcid here
 556                         // For example the rcid might be set to zero due to the user
 557                         // being the same as the performer of the change but an extension
 558                         // might still want to show it under certain conditions
 559                         Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
 560
 561                         // Build the link
 562                         if ( $rcid ) {
 563                                 $this->getOutput()->preventClickjacking();
 564                                 if ( $wgEnableAPI && $wgEnableWriteAPI
 565                                         && $user->isAllowed( 'writeapi' )
 566                                 ) {
 567                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 568                                 }
 569
 570                                 return [
 571                                         'rcid' => $rcid,
 572                                 ];
 573                         }
 574                 }
 575
 576                 // No mark as patrolled link applicable
 577                 return false;
 578         }
 579
 580         /**
 581          * @param Revision $rev
 582          *
 583          * @return string
 584          */
 585         protected function revisionDeleteLink( $rev ) {
 586                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 587                 if ( $link !== '' ) {
 588                         $link = '&#160;&#160;&#160;' . $link . ' ';
 589                 }
 590
 591                 return $link;
 592         }
 593
 594         /**
 595          * Show the new revision of the page.
 596          */
 597         public function renderNewRevision() {
 598                 $out = $this->getOutput();
 599                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 600                 # Add "current version as of X" title
 601                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 602                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 603                 # Page content may be handled by a hooked call instead...
 604                 # @codingStandardsIgnoreStart Ignoring long lines.
 605                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 606                         $this->loadNewText();
 607                         $out->setRevisionId( $this->mNewid );
 608                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 609                         $out->setArticleFlag( true );
 610
 611                         if ( !Hooks::run( 'ArticleContentViewCustom', [ $this->mNewContent, $this->mNewPage, $out ] ) ) {
 612                                 // Handled by extension
 613                         } else {
 614                                 // Normal page
 615                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 616                                         // If the Title stored in the context is the same as the one
 617                                         // of the new revision, we can use its associated WikiPage
 618                                         // object.
 619                                         $wikiPage = $this->getWikiPage();
 620                                 } else {
 621                                         // Otherwise we need to create our own WikiPage object
 622                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 623                                 }
 624
 625                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 626
 627                                 # WikiPage::getParserOutput() should not return false, but just in case
 628                                 if ( $parserOutput ) {
 629                                         // Allow extensions to change parser output here
 630                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput', [ $this, $out, $parserOutput, $wikiPage ] ) ) {
 631                                                 $out->addParserOutput( $parserOutput );
 632                                         }
 633                                 }
 634                         }
 635                 }
 636                 # @codingStandardsIgnoreEnd
 637
 638                 // Allow extensions to optionally not show the final patrolled link
 639                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 640                         # Add redundant patrol link on bottom...
 641                         $out->addHTML( $this->markPatrolledLink() );
 642                 }
 643         }
 644
 645         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 646                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 647
 648                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 649                         $parserOptions->setEditSection( false );
 650                 }
 651
 652                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 653
 654                 return $parserOutput;
 655         }
 656
 657         /**
 658          * Get the diff text, send it to the OutputPage object
 659          * Returns false if the diff could not be generated, otherwise returns true
 660          *
 661          * @param string|bool $otitle Header for old text or false
 662          * @param string|bool $ntitle Header for new text or false
 663          * @param string $notice HTML between diff header and body
 664          *
 665          * @return bool
 666          */
 667         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 668                 // Allow extensions to affect the output here
 669                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 670
 671                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 672                 if ( $diff === false ) {
 673                         $this->showMissingRevision();
 674
 675                         return false;
 676                 } else {
 677                         $this->showDiffStyle();
 678                         $this->getOutput()->addHTML( $diff );
 679
 680                         return true;
 681                 }
 682         }
 683
 684         /**
 685          * Add style sheets for diff display.
 686          */
 687         public function showDiffStyle() {
 688                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 689         }
 690
 691         /**
 692          * Get complete diff table, including header
 693          *
 694          * @param string|bool $otitle Header for old text or false
 695          * @param string|bool $ntitle Header for new text or false
 696          * @param string $notice HTML between diff header and body
 697          *
 698          * @return mixed
 699          */
 700         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 701                 $body = $this->getDiffBody();
 702                 if ( $body === false ) {
 703                         return false;
 704                 }
 705
 706                 $multi = $this->getMultiNotice();
 707                 // Display a message when the diff is empty
 708                 if ( $body === '' ) {
 709                         $notice .= '<div class="mw-diff-empty">' .
 710                                 $this->msg( 'diff-empty' )->parse() .
 711                                 "</div>\n";
 712                 }
 713
 714                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 715         }
 716
 717         /**
 718          * Get the diff table body, without header
 719          *
 720          * @return mixed (string/false)
 721          */
 722         public function getDiffBody() {
 723                 $this->mCacheHit = true;
 724                 // Check if the diff should be hidden from this user
 725                 if ( !$this->loadRevisionData() ) {
 726                         return false;
 727                 } elseif ( $this->mOldRev &&
 728                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 729                 ) {
 730                         return false;
 731                 } elseif ( $this->mNewRev &&
 732                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 733                 ) {
 734                         return false;
 735                 }
 736                 // Short-circuit
 737                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 738                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 739                 ) {
 740                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 741                                 return '';
 742                         }
 743                 }
 744                 // Cacheable?
 745                 $key = false;
 746                 $cache = ObjectCache::getMainWANInstance();
 747                 if ( $this->mOldid && $this->mNewid ) {
 748                         $key = $this->getDiffBodyCacheKey();
 749
 750                         // Try cache
 751                         if ( !$this->mRefreshCache ) {
 752                                 $difftext = $cache->get( $key );
 753                                 if ( $difftext ) {
 754                                         wfIncrStats( 'diff_cache.hit' );
 755                                         $difftext = $this->localiseLineNumbers( $difftext );
 756                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 757
 758                                         return $difftext;
 759                                 }
 760                         } // don't try to load but save the result
 761                 }
 762                 $this->mCacheHit = false;
 763
 764                 // Loadtext is permission safe, this just clears out the diff
 765                 if ( !$this->loadText() ) {
 766                         return false;
 767                 }
 768
 769                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 770
 771                 // Avoid PHP 7.1 warning from passing $this by reference
 772                 $diffEngine = $this;
 773
 774                 // Save to cache for 7 days
 775                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 776                         wfIncrStats( 'diff_cache.uncacheable' );
 777                 } elseif ( $key !== false && $difftext !== false ) {
 778                         wfIncrStats( 'diff_cache.miss' );
 779                         $cache->set( $key, $difftext, 7 * 86400 );
 780                 } else {
 781                         wfIncrStats( 'diff_cache.uncacheable' );
 782                 }
 783                 // Replace line numbers with the text in the user's language
 784                 if ( $difftext !== false ) {
 785                         $difftext = $this->localiseLineNumbers( $difftext );
 786                 }
 787
 788                 return $difftext;
 789         }
 790
 791         /**
 792          * Returns the cache key for diff body text or content.
 793          *
 794          * @since 1.23
 795          *
 796          * @throws MWException
 797          * @return string
 798          */
 799         protected function getDiffBodyCacheKey() {
 800                 if ( !$this->mOldid || !$this->mNewid ) {
 801                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 802                 }
 803
 804                 return wfMemcKey( 'diff', 'version', self::DIFF_VERSION,
 805                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 806         }
 807
 808         /**
 809          * Generate a diff, no caching.
 810          *
 811          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 812          * serialization of the given Content objects. This will fail if $old or $new are not
 813          * instances of TextContent.
 814          *
 815          * Subclasses may override this to provide a different rendering for the diff,
 816          * perhaps taking advantage of the content's native form. This is required for all content
 817          * models that are not text based.
 818          *
 819          * @since 1.21
 820          *
 821          * @param Content $old Old content
 822          * @param Content $new New content
 823          *
 824          * @throws MWException If old or new content is not an instance of TextContent.
 825          * @return bool|string
 826          */
 827         public function generateContentDiffBody( Content $old, Content $new ) {
 828                 if ( !( $old instanceof TextContent ) ) {
 829                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 830                                 "override generateContentDiffBody to fix this." );
 831                 }
 832
 833                 if ( !( $new instanceof TextContent ) ) {
 834                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 835                                 . "override generateContentDiffBody to fix this." );
 836                 }
 837
 838                 $otext = $old->serialize();
 839                 $ntext = $new->serialize();
 840
 841                 return $this->generateTextDiffBody( $otext, $ntext );
 842         }
 843
 844         /**
 845          * Generate a diff, no caching
 846          *
 847          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 848          *
 849          * @param string $otext Old text, must be already segmented
 850          * @param string $ntext New text, must be already segmented
 851          *
 852          * @return bool|string
 853          */
 854         public function generateTextDiffBody( $otext, $ntext ) {
 855                 $diff = function () use ( $otext, $ntext ) {
 856                         $time = microtime( true );
 857
 858                         $result = $this->textDiff( $otext, $ntext );
 859
 860                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 861                         MediaWikiServices::getInstance()->getStatsdDataFactory()->timing( 'diff_time', $time );
 862                         // Log requests slower than 99th percentile
 863                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 864                                 wfDebugLog( 'diff',
 865                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 866                         }
 867
 868                         return $result;
 869                 };
 870
 871                 /**
 872                  * @param Status $status
 873                  * @throws FatalError
 874                  */
 875                 $error = function ( $status ) {
 876                         throw new FatalError( $status->getWikiText() );
 877                 };
 878
 879                 // Use PoolCounter if the diff looks like it can be expensive
 880                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 881                         $work = new PoolCounterWorkViaCallback( 'diff',
 882                                 md5( $otext ) . md5( $ntext ),
 883                                 [ 'doWork' => $diff, 'error' => $error ]
 884                         );
 885                         return $work->execute();
 886                 }
 887
 888                 return $diff();
 889         }
 890
 891         /**
 892          * Generates diff, to be wrapped internally in a logging/instrumentation
 893          *
 894          * @param string $otext Old text, must be already segmented
 895          * @param string $ntext New text, must be already segmented
 896          * @return bool|string
 897          */
 898         protected function textDiff( $otext, $ntext ) {
 899                 global $wgExternalDiffEngine, $wgContLang;
 900
 901                 $otext = str_replace( "\r\n", "\n", $otext );
 902                 $ntext = str_replace( "\r\n", "\n", $ntext );
 903
 904                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 905                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 906                         $wgExternalDiffEngine = false;
 907                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 908                         // Same as above, but with no deprecation warnings
 909                         $wgExternalDiffEngine = false;
 910                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 911                         // And prevent people from shooting themselves in the foot...
 912                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 913                         $wgExternalDiffEngine = false;
 914                 }
 915
 916                 // Better external diff engine, the 2 may some day be dropped
 917                 // This one does the escaping and segmenting itself
 918                 if ( function_exists( 'wikidiff2_do_diff' ) && $wgExternalDiffEngine === false ) {
 919                         $wikidiff2Version = phpversion( 'wikidiff2' );
 920                         if (
 921                                 $wikidiff2Version !== false &&
 922                                 version_compare( $wikidiff2Version, '0.3', '>=' )
 923                         ) {
 924                                 $text = wikidiff2_do_diff(
 925                                         $otext,
 926                                         $ntext,
 927                                         2,
 928                                         $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' )
 929                                 );
 930                         } else {
 931                                 // Don't pass the 4th parameter for compatibility with older versions of wikidiff2
 932                                 $text = wikidiff2_do_diff(
 933                                         $otext,
 934                                         $ntext,
 935                                         2
 936                                 );
 937
 938                                 // Log a warning in case the configuration value is set to not silently ignore it
 939                                 if ( $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' ) > 0 ) {
 940                                         wfLogWarning( '$wgWikiDiff2MovedParagraphDetectionCutoff is set but has no
 941                                                 effect since the used version of WikiDiff2 does not support it.' );
 942                                 }
 943                         }
 944
 945                         $text .= $this->debug( 'wikidiff2' );
 946
 947                         return $text;
 948                 } elseif ( $wgExternalDiffEngine !== false && is_executable( $wgExternalDiffEngine ) ) {
 949                         # Diff via the shell
 950                         $tmpDir = wfTempDir();
 951                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 952                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 953
 954                         $tempFile1 = fopen( $tempName1, "w" );
 955                         if ( !$tempFile1 ) {
 956                                 return false;
 957                         }
 958                         $tempFile2 = fopen( $tempName2, "w" );
 959                         if ( !$tempFile2 ) {
 960                                 return false;
 961                         }
 962                         fwrite( $tempFile1, $otext );
 963                         fwrite( $tempFile2, $ntext );
 964                         fclose( $tempFile1 );
 965                         fclose( $tempFile2 );
 966                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 967                         $difftext = wfShellExec( $cmd );
 968                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 969                         unlink( $tempName1 );
 970                         unlink( $tempName2 );
 971
 972                         return $difftext;
 973                 }
 974
 975                 # Native PHP diff
 976                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 977                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 978                 $diffs = new Diff( $ota, $nta );
 979                 $formatter = new TableDiffFormatter();
 980                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 981
 982                 return $difftext;
 983         }
 984
 985         /**
 986          * Generate a debug comment indicating diff generating time,
 987          * server node, and generator backend.
 988          *
 989          * @param string $generator : What diff engine was used
 990          *
 991          * @return string
 992          */
 993         protected function debug( $generator = "internal" ) {
 994                 global $wgShowHostnames;
 995                 if ( !$this->enableDebugComment ) {
 996                         return '';
 997                 }
 998                 $data = [ $generator ];
 999                 if ( $wgShowHostnames ) {
1000                         $data[] = wfHostname();
1001                 }
1002                 $data[] = wfTimestamp( TS_DB );
1003
1004                 return "<!-- diff generator: " .
1005                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1006                         " -->\n";
1007         }
1008
1009         /**
1010          * Replace line numbers with the text in the user's language
1011          *
1012          * @param string $text
1013          *
1014          * @return mixed
1015          */
1016         public function localiseLineNumbers( $text ) {
1017                 return preg_replace_callback(
1018                         '/<!--LINE (\d+)-->/',
1019                         [ $this, 'localiseLineNumbersCb' ],
1020                         $text
1021                 );
1022         }
1023
1024         public function localiseLineNumbersCb( $matches ) {
1025                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1026                         return '';
1027                 }
1028
1029                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1030         }
1031
1032         /**
1033          * If there are revisions between the ones being compared, return a note saying so.
1034          *
1035          * @return string
1036          */
1037         public function getMultiNotice() {
1038                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1039                         return '';
1040                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1041                         // Comparing two different pages? Count would be meaningless.
1042                         return '';
1043                 }
1044
1045                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1046                         $oldRev = $this->mNewRev; // flip
1047                         $newRev = $this->mOldRev; // flip
1048                 } else { // normal case
1049                         $oldRev = $this->mOldRev;
1050                         $newRev = $this->mNewRev;
1051                 }
1052
1053                 // Sanity: don't show the notice if too many rows must be scanned
1054                 // @todo show some special message for that case
1055                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1056                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1057                         $limit = 100; // use diff-multi-manyusers if too many users
1058                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1059                         $numUsers = count( $users );
1060
1061                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1062                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1063                         }
1064
1065                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1066                 }
1067
1068                 return ''; // nothing
1069         }
1070
1071         /**
1072          * Get a notice about how many intermediate edits and users there are
1073          *
1074          * @param int $numEdits
1075          * @param int $numUsers
1076          * @param int $limit
1077          *
1078          * @return string
1079          */
1080         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1081                 if ( $numUsers === 0 ) {
1082                         $msg = 'diff-multi-sameuser';
1083                 } elseif ( $numUsers > $limit ) {
1084                         $msg = 'diff-multi-manyusers';
1085                         $numUsers = $limit;
1086                 } else {
1087                         $msg = 'diff-multi-otherusers';
1088                 }
1089
1090                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1091         }
1092
1093         /**
1094          * Get a header for a specified revision.
1095          *
1096          * @param Revision $rev
1097          * @param string $complete 'complete' to get the header wrapped depending
1098          *        the visibility of the revision and a link to edit the page.
1099          *
1100          * @return string HTML fragment
1101          */
1102         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1103                 $lang = $this->getLanguage();
1104                 $user = $this->getUser();
1105                 $revtimestamp = $rev->getTimestamp();
1106                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1107                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1108                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1109
1110                 $header = $this->msg(
1111                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1112                         $timestamp,
1113                         $dateofrev,
1114                         $timeofrev
1115                 )->escaped();
1116
1117                 if ( $complete !== 'complete' ) {
1118                         return $header;
1119                 }
1120
1121                 $title = $rev->getTitle();
1122
1123                 $header = Linker::linkKnown( $title, $header, [],
1124                         [ 'oldid' => $rev->getId() ] );
1125
1126                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1127                         $editQuery = [ 'action' => 'edit' ];
1128                         if ( !$rev->isCurrent() ) {
1129                                 $editQuery['oldid'] = $rev->getId();
1130                         }
1131
1132                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1133                         $msg = $this->msg( $key )->escaped();
1134                         $editLink = $this->msg( 'parentheses' )->rawParams(
1135                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1136                         $header .= ' ' . Html::rawElement(
1137                                 'span',
1138                                 [ 'class' => 'mw-diff-edit' ],
1139                                 $editLink
1140                         );
1141                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1142                                 $header = Html::rawElement(
1143                                         'span',
1144                                         [ 'class' => 'history-deleted' ],
1145                                         $header
1146                                 );
1147                         }
1148                 } else {
1149                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1150                 }
1151
1152                 return $header;
1153         }
1154
1155         /**
1156          * Add the header to a diff body
1157          *
1158          * @param string $diff Diff body
1159          * @param string $otitle Old revision header
1160          * @param string $ntitle New revision header
1161          * @param string $multi Notice telling user that there are intermediate
1162          *   revisions between the ones being compared
1163          * @param string $notice Other notices, e.g. that user is viewing deleted content
1164          *
1165          * @return string
1166          */
1167         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1168                 // shared.css sets diff in interface language/dir, but the actual content
1169                 // is often in a different language, mostly the page content language/dir
1170                 $header = Html::openElement( 'table', [
1171                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1172                         'data-mw' => 'interface',
1173                 ] );
1174                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1175
1176                 if ( !$diff && !$otitle ) {
1177                         $header .= "
1178                         <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1179                         <td class=\"diff-ntitle\">{$ntitle}</td>
1180                         </tr>";
1181                         $multiColspan = 1;
1182                 } else {
1183                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1184                                 $header .= "
1185                                 <col class=\"diff-marker\" />
1186                                 <col class=\"diff-content\" />
1187                                 <col class=\"diff-marker\" />
1188                                 <col class=\"diff-content\" />";
1189                                 $colspan = 2;
1190                                 $multiColspan = 4;
1191                         } else {
1192                                 $colspan = 1;
1193                                 $multiColspan = 2;
1194                         }
1195                         if ( $otitle || $ntitle ) {
1196                                 $header .= "
1197                                 <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1198                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1199                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1200                                 </tr>";
1201                         }
1202                 }
1203
1204                 if ( $multi != '' ) {
1205                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1206                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1207                 }
1208                 if ( $notice != '' ) {
1209                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1210                                 "lang=\"{$userLang}\">{$notice}</td></tr>";
1211                 }
1212
1213                 return $header . $diff . "</table>";
1214         }
1215
1216         /**
1217          * Use specified text instead of loading from the database
1218          * @param Content $oldContent
1219          * @param Content $newContent
1220          * @since 1.21
1221          */
1222         public function setContent( Content $oldContent, Content $newContent ) {
1223                 $this->mOldContent = $oldContent;
1224                 $this->mNewContent = $newContent;
1225
1226                 $this->mTextLoaded = 2;
1227                 $this->mRevisionsLoaded = true;
1228         }
1229
1230         /**
1231          * Set the language in which the diff text is written
1232          * (Defaults to page content language).
1233          * @param Language|string $lang
1234          * @since 1.19
1235          */
1236         public function setTextLanguage( $lang ) {
1237                 $this->mDiffLang = wfGetLangObj( $lang );
1238         }
1239
1240         /**
1241          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1242          * to a pair of actual integers representing revision ids.
1243          *
1244          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1245          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1246          *
1247          * @return int[] List of two revision ids, older first, later second.
1248          *     Zero signifies invalid argument passed.
1249          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1250          */
1251         public function mapDiffPrevNext( $old, $new ) {
1252                 if ( $new === 'prev' ) {
1253                         // Show diff between revision $old and the previous one. Get previous one from DB.
1254                         $newid = intval( $old );
1255                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1256                 } elseif ( $new === 'next' ) {
1257                         // Show diff between revision $old and the next one. Get next one from DB.
1258                         $oldid = intval( $old );
1259                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1260                 } else {
1261                         $oldid = intval( $old );
1262                         $newid = intval( $new );
1263                 }
1264
1265                 return [ $oldid, $newid ];
1266         }
1267
1268         /**
1269          * Load revision IDs
1270          */
1271         private function loadRevisionIds() {
1272                 if ( $this->mRevisionsIdsLoaded ) {
1273                         return;
1274                 }
1275
1276                 $this->mRevisionsIdsLoaded = true;
1277
1278                 $old = $this->mOldid;
1279                 $new = $this->mNewid;
1280
1281                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1282                 if ( $new === 'next' && $this->mNewid === false ) {
1283                         # if no result, NewId points to the newest old revision. The only newer
1284                         # revision is cur, which is "0".
1285                         $this->mNewid = 0;
1286                 }
1287
1288                 Hooks::run(
1289                         'NewDifferenceEngine',
1290                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1291                 );
1292         }
1293
1294         /**
1295          * Load revision metadata for the specified articles. If newid is 0, then compare
1296          * the old article in oldid to the current article; if oldid is 0, then
1297          * compare the current article to the immediately previous one (ignoring the
1298          * value of newid).
1299          *
1300          * If oldid is false, leave the corresponding revision object set
1301          * to false. This is impossible via ordinary user input, and is provided for
1302          * API convenience.
1303          *
1304          * @return bool
1305          */
1306         public function loadRevisionData() {
1307                 if ( $this->mRevisionsLoaded ) {
1308                         return true;
1309                 }
1310
1311                 // Whether it succeeds or fails, we don't want to try again
1312                 $this->mRevisionsLoaded = true;
1313
1314                 $this->loadRevisionIds();
1315
1316                 // Load the new revision object
1317                 if ( $this->mNewid ) {
1318                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1319                 } else {
1320                         $this->mNewRev = Revision::newFromTitle(
1321                                 $this->getTitle(),
1322                                 false,
1323                                 Revision::READ_NORMAL
1324                         );
1325                 }
1326
1327                 if ( !$this->mNewRev instanceof Revision ) {
1328                         return false;
1329                 }
1330
1331                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1332                 $this->mNewid = $this->mNewRev->getId();
1333                 $this->mNewPage = $this->mNewRev->getTitle();
1334
1335                 // Load the old revision object
1336                 $this->mOldRev = false;
1337                 if ( $this->mOldid ) {
1338                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1339                 } elseif ( $this->mOldid === 0 ) {
1340                         $rev = $this->mNewRev->getPrevious();
1341                         if ( $rev ) {
1342                                 $this->mOldid = $rev->getId();
1343                                 $this->mOldRev = $rev;
1344                         } else {
1345                                 // No previous revision; mark to show as first-version only.
1346                                 $this->mOldid = false;
1347                                 $this->mOldRev = false;
1348                         }
1349                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1350
1351                 if ( is_null( $this->mOldRev ) ) {
1352                         return false;
1353                 }
1354
1355                 if ( $this->mOldRev ) {
1356                         $this->mOldPage = $this->mOldRev->getTitle();
1357                 }
1358
1359                 // Load tags information for both revisions
1360                 $dbr = wfGetDB( DB_REPLICA );
1361                 if ( $this->mOldid !== false ) {
1362                         $this->mOldTags = $dbr->selectField(
1363                                 'tag_summary',
1364                                 'ts_tags',
1365                                 [ 'ts_rev_id' => $this->mOldid ],
1366                                 __METHOD__
1367                         );
1368                 } else {
1369                         $this->mOldTags = false;
1370                 }
1371                 $this->mNewTags = $dbr->selectField(
1372                         'tag_summary',
1373                         'ts_tags',
1374                         [ 'ts_rev_id' => $this->mNewid ],
1375                         __METHOD__
1376                 );
1377
1378                 return true;
1379         }
1380
1381         /**
1382          * Load the text of the revisions, as well as revision data.
1383          *
1384          * @return bool
1385          */
1386         public function loadText() {
1387                 if ( $this->mTextLoaded == 2 ) {
1388                         return true;
1389                 }
1390
1391                 // Whether it succeeds or fails, we don't want to try again
1392                 $this->mTextLoaded = 2;
1393
1394                 if ( !$this->loadRevisionData() ) {
1395                         return false;
1396                 }
1397
1398                 if ( $this->mOldRev ) {
1399                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1400                         if ( $this->mOldContent === null ) {
1401                                 return false;
1402                         }
1403                 }
1404
1405                 if ( $this->mNewRev ) {
1406                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1407                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1408                         if ( $this->mNewContent === null ) {
1409                                 return false;
1410                         }
1411                 }
1412
1413                 return true;
1414         }
1415
1416         /**
1417          * Load the text of the new revision, not the old one
1418          *
1419          * @return bool
1420          */
1421         public function loadNewText() {
1422                 if ( $this->mTextLoaded >= 1 ) {
1423                         return true;
1424                 }
1425
1426                 $this->mTextLoaded = 1;
1427
1428                 if ( !$this->loadRevisionData() ) {
1429                         return false;
1430                 }
1431
1432                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1433
1434                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1435
1436                 return true;
1437         }
1438
1439 }