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                                 array_merge(
 186                                         Revision::selectArchiveFields(),
 187                                         [ 'ar_namespace', 'ar_title' ]
 188                                 ),
 189                                 [ 'ar_rev_id' => $id ],
 190                                 __METHOD__ );
 191                         if ( $row ) {
 192                                 $rev = Revision::newFromArchiveRow( $row );
 193                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 194
 195                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
 196                                         'target' => $title->getPrefixedText(),
 197                                         'timestamp' => $rev->getTimestamp()
 198                                 ] );
 199                         }
 200                 }
 201
 202                 return false;
 203         }
 204
 205         /**
 206          * Build a wikitext link toward a deleted revision, if viewable.
 207          *
 208          * @param int $id Revision ID
 209          *
 210          * @return string Wikitext fragment
 211          */
 212         public function deletedIdMarker( $id ) {
 213                 $link = $this->deletedLink( $id );
 214                 if ( $link ) {
 215                         return "[$link $id]";
 216                 } else {
 217                         return (string)$id;
 218                 }
 219         }
 220
 221         private function showMissingRevision() {
 222                 $out = $this->getOutput();
 223
 224                 $missing = [];
 225                 if ( $this->mOldRev === null ||
 226                         ( $this->mOldRev && $this->mOldContent === null )
 227                 ) {
 228                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 229                 }
 230                 if ( $this->mNewRev === null ||
 231                         ( $this->mNewRev && $this->mNewContent === null )
 232                 ) {
 233                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 234                 }
 235
 236                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 237                 $msg = $this->msg( 'difference-missing-revision' )
 238                         ->params( $this->getLanguage()->listToText( $missing ) )
 239                         ->numParams( count( $missing ) )
 240                         ->parseAsBlock();
 241                 $out->addHTML( $msg );
 242         }
 243
 244         public function showDiffPage( $diffOnly = false ) {
 245                 # Allow frames except in certain special cases
 246                 $out = $this->getOutput();
 247                 $out->allowClickjacking();
 248                 $out->setRobotPolicy( 'noindex,nofollow' );
 249
 250                 // Allow extensions to add any extra output here
 251                 Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
 252
 253                 if ( !$this->loadRevisionData() ) {
 254                         if ( Hooks::run( 'DifferenceEngineShowDiffPageMaybeShowMissingRevision', [ $this ] ) ) {
 255                                 $this->showMissingRevision();
 256                         }
 257                         return;
 258                 }
 259
 260                 $user = $this->getUser();
 261                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 262                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 263                         $permErrors = wfMergeErrorArrays( $permErrors,
 264                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 265                 }
 266                 if ( count( $permErrors ) ) {
 267                         throw new PermissionsError( 'read', $permErrors );
 268                 }
 269
 270                 $rollback = '';
 271
 272                 $query = [];
 273                 # Carry over 'diffonly' param via navigation links
 274                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 275                         $query['diffonly'] = $diffOnly;
 276                 }
 277                 # Cascade unhide param in links for easy deletion browsing
 278                 if ( $this->unhide ) {
 279                         $query['unhide'] = 1;
 280                 }
 281
 282                 # Check if one of the revisions is deleted/suppressed
 283                 $deleted = $suppressed = false;
 284                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 285
 286                 $revisionTools = [];
 287
 288                 # mOldRev is false if the difference engine is called with a "vague" query for
 289                 # a diff between a version V and its previous version V' AND the version V
 290                 # is the first version of that article. In that case, V' does not exist.
 291                 if ( $this->mOldRev === false ) {
 292                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 293                         $samePage = true;
 294                         $oldHeader = '';
 295                         // Allow extensions to change the $oldHeader variable
 296                         Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
 297                 } else {
 298                         Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 299
 300                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 301                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 302                                 $samePage = true;
 303                         } else {
 304                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 305                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 306                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 307                                 $samePage = false;
 308                         }
 309
 310                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 311                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 312                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 313                                         if ( $rollbackLink ) {
 314                                                 $out->preventClickjacking();
 315                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 316                                         }
 317                                 }
 318
 319                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 320                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 321                                 ) {
 322                                         $undoLink = Html::element( 'a', [
 323                                                         'href' => $this->mNewPage->getLocalURL( [
 324                                                                 'action' => 'edit',
 325                                                                 'undoafter' => $this->mOldid,
 326                                                                 'undo' => $this->mNewid
 327                                                         ] ),
 328                                                         'title' => Linker::titleAttrib( 'undo' ),
 329                                                 ],
 330                                                 $this->msg( 'editundo' )->text()
 331                                         );
 332                                         $revisionTools['mw-diff-undo'] = $undoLink;
 333                                 }
 334                         }
 335
 336                         # Make "previous revision link"
 337                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 338                                 $prevlink = Linker::linkKnown(
 339                                         $this->mOldPage,
 340                                         $this->msg( 'previousdiff' )->escaped(),
 341                                         [ 'id' => 'differences-prevlink' ],
 342                                         [ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
 343                                 );
 344                         } else {
 345                                 $prevlink = '&#160;';
 346                         }
 347
 348                         if ( $this->mOldRev->isMinor() ) {
 349                                 $oldminor = ChangesList::flag( 'minor' );
 350                         } else {
 351                                 $oldminor = '';
 352                         }
 353
 354                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 355                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 356                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );
 357
 358                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 359                                 '<div id="mw-diff-otitle2">' .
 360                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 361                                 '<div id="mw-diff-otitle3">' . $oldminor .
 362                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 363                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 364                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 365
 366                         // Allow extensions to change the $oldHeader variable
 367                         Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
 368                                 $diffOnly, $ldel, $this->unhide ] );
 369
 370                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 371                                 $deleted = true; // old revisions text is hidden
 372                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 373                                         $suppressed = true; // also suppressed
 374                                 }
 375                         }
 376
 377                         # Check if this user can see the revisions
 378                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 379                                 $allowed = false;
 380                         }
 381                 }
 382
 383                 $out->addJsConfigVars( [
 384                         'wgDiffOldId' => $this->mOldid,
 385                         'wgDiffNewId' => $this->mNewid,
 386                 ] );
 387
 388                 # Make "next revision link"
 389                 # Skip next link on the top revision
 390                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 391                         $nextlink = Linker::linkKnown(
 392                                 $this->mNewPage,
 393                                 $this->msg( 'nextdiff' )->escaped(),
 394                                 [ 'id' => 'differences-nextlink' ],
 395                                 [ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
 396                         );
 397                 } else {
 398                         $nextlink = '&#160;';
 399                 }
 400
 401                 if ( $this->mNewRev->isMinor() ) {
 402                         $newminor = ChangesList::flag( 'minor' );
 403                 } else {
 404                         $newminor = '';
 405                 }
 406
 407                 # Handle RevisionDelete links...
 408                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 409
 410                 # Allow extensions to define their own revision tools
 411                 Hooks::run( 'DiffRevisionTools',
 412                         [ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
 413                 $formattedRevisionTools = [];
 414                 // Put each one in parentheses (poor man's button)
 415                 foreach ( $revisionTools as $key => $tool ) {
 416                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 417                         $element = Html::rawElement(
 418                                 'span',
 419                                 [ 'class' => $toolClass ],
 420                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 421                         );
 422                         $formattedRevisionTools[] = $element;
 423                 }
 424                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 425                         ' ' . implode( ' ', $formattedRevisionTools );
 426                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );
 427
 428                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 429                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 430                         " $rollback</div>" .
 431                         '<div id="mw-diff-ntitle3">' . $newminor .
 432                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 433                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 434                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 435
 436                 // Allow extensions to change the $newHeader variable
 437                 Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
 438                         $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
 439
 440                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 441                         $deleted = true; // new revisions text is hidden
 442                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 443                                 $suppressed = true; // also suppressed
 444                         }
 445                 }
 446
 447                 # If the diff cannot be shown due to a deleted revision, then output
 448                 # the diff header and links to unhide (if available)...
 449                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 450                         $this->showDiffStyle();
 451                         $multi = $this->getMultiNotice();
 452                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 453                         if ( !$allowed ) {
 454                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 455                                 # Give explanation for why revision is not visible
 456                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 457                                         [ $msg ] );
 458                         } else {
 459                                 # Give explanation and add a link to view the diff...
 460                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
 461                                 $link = $this->getTitle()->getFullURL( $query );
 462                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 463                                 $out->wrapWikiMsg(
 464                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 465                                         [ $msg, $link ]
 466                                 );
 467                         }
 468                 # Otherwise, output a regular diff...
 469                 } else {
 470                         # Add deletion notice if the user is viewing deleted content
 471                         $notice = '';
 472                         if ( $deleted ) {
 473                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 474                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 475                                         $this->msg( $msg )->parse() .
 476                                         "</div>\n";
 477                         }
 478                         $this->showDiff( $oldHeader, $newHeader, $notice );
 479                         if ( !$diffOnly ) {
 480                                 $this->renderNewRevision();
 481                         }
 482                 }
 483         }
 484
 485         /**
 486          * Build a link to mark a change as patrolled.
 487          *
 488          * Returns empty string if there's either no revision to patrol or the user is not allowed to.
 489          * Side effect: When the patrol link is build, this method will call
 490          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 491          *
 492          * @return string HTML or empty string
 493          */
 494         public function markPatrolledLink() {
 495                 if ( $this->mMarkPatrolledLink === null ) {
 496                         $linkInfo = $this->getMarkPatrolledLinkInfo();
 497                         // If false, there is no patrol link needed/allowed
 498                         if ( !$linkInfo ) {
 499                                 $this->mMarkPatrolledLink = '';
 500                         } else {
 501                                 $this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
 502                                         Linker::linkKnown(
 503                                                 $this->mNewPage,
 504                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 505                                                 [],
 506                                                 [
 507                                                         'action' => 'markpatrolled',
 508                                                         'rcid' => $linkInfo['rcid'],
 509                                                 ]
 510                                         ) . ']</span>';
 511                                 // Allow extensions to change the markpatrolled link
 512                                 Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
 513                                         &$this->mMarkPatrolledLink, $linkInfo['rcid'] ] );
 514                         }
 515                 }
 516                 return $this->mMarkPatrolledLink;
 517         }
 518
 519         /**
 520          * Returns an array of meta data needed to build a "mark as patrolled" link and
 521          * adds the mediawiki.page.patrol.ajax to the output.
 522          *
 523          * @return array|false An array of meta data for a patrol link (rcid only)
 524          *  or false if no link is needed
 525          */
 526         protected function getMarkPatrolledLinkInfo() {
 527                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 528
 529                 $user = $this->getUser();
 530
 531                 // Prepare a change patrol link, if applicable
 532                 if (
 533                         // Is patrolling enabled and the user allowed to?
 534                         $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 535                         // Only do this if the revision isn't more than 6 hours older
 536                         // than the Max RC age (6h because the RC might not be cleaned out regularly)
 537                         RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 538                 ) {
 539                         // Look for an unpatrolled change corresponding to this diff
 540                         $db = wfGetDB( DB_REPLICA );
 541                         $change = RecentChange::newFromConds(
 542                                 [
 543                                         'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 544                                         'rc_this_oldid' => $this->mNewid,
 545                                         'rc_patrolled' => 0
 546                                 ],
 547                                 __METHOD__
 548                         );
 549
 550                         if ( $change && !$change->getPerformer()->equals( $user ) ) {
 551                                 $rcid = $change->getAttribute( 'rc_id' );
 552                         } else {
 553                                 // None found or the page has been created by the current user.
 554                                 // If the user could patrol this it already would be patrolled
 555                                 $rcid = 0;
 556                         }
 557
 558                         // Allow extensions to possibly change the rcid here
 559                         // For example the rcid might be set to zero due to the user
 560                         // being the same as the performer of the change but an extension
 561                         // might still want to show it under certain conditions
 562                         Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
 563
 564                         // Build the link
 565                         if ( $rcid ) {
 566                                 $this->getOutput()->preventClickjacking();
 567                                 if ( $wgEnableAPI && $wgEnableWriteAPI
 568                                         && $user->isAllowed( 'writeapi' )
 569                                 ) {
 570                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 571                                 }
 572
 573                                 return [
 574                                         'rcid' => $rcid,
 575                                 ];
 576                         }
 577                 }
 578
 579                 // No mark as patrolled link applicable
 580                 return false;
 581         }
 582
 583         /**
 584          * @param Revision $rev
 585          *
 586          * @return string
 587          */
 588         protected function revisionDeleteLink( $rev ) {
 589                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 590                 if ( $link !== '' ) {
 591                         $link = '&#160;&#160;&#160;' . $link . ' ';
 592                 }
 593
 594                 return $link;
 595         }
 596
 597         /**
 598          * Show the new revision of the page.
 599          */
 600         public function renderNewRevision() {
 601                 $out = $this->getOutput();
 602                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 603                 # Add "current version as of X" title
 604                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 605                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 606                 # Page content may be handled by a hooked call instead...
 607                 # @codingStandardsIgnoreStart Ignoring long lines.
 608                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 609                         $this->loadNewText();
 610                         $out->setRevisionId( $this->mNewid );
 611                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 612                         $out->setArticleFlag( true );
 613
 614                         if ( !Hooks::run( 'ArticleContentViewCustom', [ $this->mNewContent, $this->mNewPage, $out ] ) ) {
 615                                 // Handled by extension
 616                         } else {
 617                                 // Normal page
 618                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 619                                         // If the Title stored in the context is the same as the one
 620                                         // of the new revision, we can use its associated WikiPage
 621                                         // object.
 622                                         $wikiPage = $this->getWikiPage();
 623                                 } else {
 624                                         // Otherwise we need to create our own WikiPage object
 625                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 626                                 }
 627
 628                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 629
 630                                 # WikiPage::getParserOutput() should not return false, but just in case
 631                                 if ( $parserOutput ) {
 632                                         // Allow extensions to change parser output here
 633                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput', [ $this, $out, $parserOutput, $wikiPage ] ) ) {
 634                                                 $out->addParserOutput( $parserOutput );
 635                                         }
 636                                 }
 637                         }
 638                 }
 639                 # @codingStandardsIgnoreEnd
 640
 641                 // Allow extensions to optionally not show the final patrolled link
 642                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 643                         # Add redundant patrol link on bottom...
 644                         $out->addHTML( $this->markPatrolledLink() );
 645                 }
 646         }
 647
 648         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 649                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 650
 651                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 652                         $parserOptions->setEditSection( false );
 653                 }
 654
 655                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 656
 657                 return $parserOutput;
 658         }
 659
 660         /**
 661          * Get the diff text, send it to the OutputPage object
 662          * Returns false if the diff could not be generated, otherwise returns true
 663          *
 664          * @param string|bool $otitle Header for old text or false
 665          * @param string|bool $ntitle Header for new text or false
 666          * @param string $notice HTML between diff header and body
 667          *
 668          * @return bool
 669          */
 670         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 671                 // Allow extensions to affect the output here
 672                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 673
 674                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 675                 if ( $diff === false ) {
 676                         $this->showMissingRevision();
 677
 678                         return false;
 679                 } else {
 680                         $this->showDiffStyle();
 681                         $this->getOutput()->addHTML( $diff );
 682
 683                         return true;
 684                 }
 685         }
 686
 687         /**
 688          * Add style sheets for diff display.
 689          */
 690         public function showDiffStyle() {
 691                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 692         }
 693
 694         /**
 695          * Get complete diff table, including header
 696          *
 697          * @param string|bool $otitle Header for old text or false
 698          * @param string|bool $ntitle Header for new text or false
 699          * @param string $notice HTML between diff header and body
 700          *
 701          * @return mixed
 702          */
 703         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 704                 $body = $this->getDiffBody();
 705                 if ( $body === false ) {
 706                         return false;
 707                 }
 708
 709                 $multi = $this->getMultiNotice();
 710                 // Display a message when the diff is empty
 711                 if ( $body === '' ) {
 712                         $notice .= '<div class="mw-diff-empty">' .
 713                                 $this->msg( 'diff-empty' )->parse() .
 714                                 "</div>\n";
 715                 }
 716
 717                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 718         }
 719
 720         /**
 721          * Get the diff table body, without header
 722          *
 723          * @return mixed (string/false)
 724          */
 725         public function getDiffBody() {
 726                 $this->mCacheHit = true;
 727                 // Check if the diff should be hidden from this user
 728                 if ( !$this->loadRevisionData() ) {
 729                         return false;
 730                 } elseif ( $this->mOldRev &&
 731                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 732                 ) {
 733                         return false;
 734                 } elseif ( $this->mNewRev &&
 735                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 736                 ) {
 737                         return false;
 738                 }
 739                 // Short-circuit
 740                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 741                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 742                 ) {
 743                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 744                                 return '';
 745                         }
 746                 }
 747                 // Cacheable?
 748                 $key = false;
 749                 $cache = ObjectCache::getMainWANInstance();
 750                 if ( $this->mOldid && $this->mNewid ) {
 751                         $key = $this->getDiffBodyCacheKey();
 752
 753                         // Try cache
 754                         if ( !$this->mRefreshCache ) {
 755                                 $difftext = $cache->get( $key );
 756                                 if ( $difftext ) {
 757                                         wfIncrStats( 'diff_cache.hit' );
 758                                         $difftext = $this->localiseLineNumbers( $difftext );
 759                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 760
 761                                         return $difftext;
 762                                 }
 763                         } // don't try to load but save the result
 764                 }
 765                 $this->mCacheHit = false;
 766
 767                 // Loadtext is permission safe, this just clears out the diff
 768                 if ( !$this->loadText() ) {
 769                         return false;
 770                 }
 771
 772                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 773
 774                 // Avoid PHP 7.1 warning from passing $this by reference
 775                 $diffEngine = $this;
 776
 777                 // Save to cache for 7 days
 778                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 779                         wfIncrStats( 'diff_cache.uncacheable' );
 780                 } elseif ( $key !== false && $difftext !== false ) {
 781                         wfIncrStats( 'diff_cache.miss' );
 782                         $cache->set( $key, $difftext, 7 * 86400 );
 783                 } else {
 784                         wfIncrStats( 'diff_cache.uncacheable' );
 785                 }
 786                 // Replace line numbers with the text in the user's language
 787                 if ( $difftext !== false ) {
 788                         $difftext = $this->localiseLineNumbers( $difftext );
 789                 }
 790
 791                 return $difftext;
 792         }
 793
 794         /**
 795          * Returns the cache key for diff body text or content.
 796          *
 797          * @since 1.23
 798          *
 799          * @throws MWException
 800          * @return string
 801          */
 802         protected function getDiffBodyCacheKey() {
 803                 if ( !$this->mOldid || !$this->mNewid ) {
 804                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 805                 }
 806
 807                 return wfMemcKey( 'diff', 'version', self::DIFF_VERSION,
 808                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 809         }
 810
 811         /**
 812          * Generate a diff, no caching.
 813          *
 814          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 815          * serialization of the given Content objects. This will fail if $old or $new are not
 816          * instances of TextContent.
 817          *
 818          * Subclasses may override this to provide a different rendering for the diff,
 819          * perhaps taking advantage of the content's native form. This is required for all content
 820          * models that are not text based.
 821          *
 822          * @since 1.21
 823          *
 824          * @param Content $old Old content
 825          * @param Content $new New content
 826          *
 827          * @throws MWException If old or new content is not an instance of TextContent.
 828          * @return bool|string
 829          */
 830         public function generateContentDiffBody( Content $old, Content $new ) {
 831                 if ( !( $old instanceof TextContent ) ) {
 832                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 833                                 "override generateContentDiffBody to fix this." );
 834                 }
 835
 836                 if ( !( $new instanceof TextContent ) ) {
 837                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 838                                 . "override generateContentDiffBody to fix this." );
 839                 }
 840
 841                 $otext = $old->serialize();
 842                 $ntext = $new->serialize();
 843
 844                 return $this->generateTextDiffBody( $otext, $ntext );
 845         }
 846
 847         /**
 848          * Generate a diff, no caching
 849          *
 850          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 851          *
 852          * @param string $otext Old text, must be already segmented
 853          * @param string $ntext New text, must be already segmented
 854          *
 855          * @return bool|string
 856          */
 857         public function generateTextDiffBody( $otext, $ntext ) {
 858                 $diff = function () use ( $otext, $ntext ) {
 859                         $time = microtime( true );
 860
 861                         $result = $this->textDiff( $otext, $ntext );
 862
 863                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 864                         MediaWikiServices::getInstance()->getStatsdDataFactory()->timing( 'diff_time', $time );
 865                         // Log requests slower than 99th percentile
 866                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 867                                 wfDebugLog( 'diff',
 868                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 869                         }
 870
 871                         return $result;
 872                 };
 873
 874                 /**
 875                  * @param Status $status
 876                  * @throws FatalError
 877                  */
 878                 $error = function ( $status ) {
 879                         throw new FatalError( $status->getWikiText() );
 880                 };
 881
 882                 // Use PoolCounter if the diff looks like it can be expensive
 883                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 884                         $work = new PoolCounterWorkViaCallback( 'diff',
 885                                 md5( $otext ) . md5( $ntext ),
 886                                 [ 'doWork' => $diff, 'error' => $error ]
 887                         );
 888                         return $work->execute();
 889                 }
 890
 891                 return $diff();
 892         }
 893
 894         /**
 895          * Generates diff, to be wrapped internally in a logging/instrumentation
 896          *
 897          * @param string $otext Old text, must be already segmented
 898          * @param string $ntext New text, must be already segmented
 899          * @return bool|string
 900          */
 901         protected function textDiff( $otext, $ntext ) {
 902                 global $wgExternalDiffEngine, $wgContLang;
 903
 904                 $otext = str_replace( "\r\n", "\n", $otext );
 905                 $ntext = str_replace( "\r\n", "\n", $ntext );
 906
 907                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 908                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 909                         $wgExternalDiffEngine = false;
 910                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 911                         // Same as above, but with no deprecation warnings
 912                         $wgExternalDiffEngine = false;
 913                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 914                         // And prevent people from shooting themselves in the foot...
 915                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 916                         $wgExternalDiffEngine = false;
 917                 }
 918
 919                 // Better external diff engine, the 2 may some day be dropped
 920                 // This one does the escaping and segmenting itself
 921                 if ( function_exists( 'wikidiff2_do_diff' ) && $wgExternalDiffEngine === false ) {
 922                         $wikidiff2Version = phpversion( 'wikidiff2' );
 923                         if (
 924                                 $wikidiff2Version !== false &&
 925                                 version_compare( $wikidiff2Version, '0.3', '>=' )
 926                         ) {
 927                                 $text = wikidiff2_do_diff(
 928                                         $otext,
 929                                         $ntext,
 930                                         2,
 931                                         $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' )
 932                                 );
 933                         } else {
 934                                 // Don't pass the 4th parameter for compatibility with older versions of wikidiff2
 935                                 $text = wikidiff2_do_diff(
 936                                         $otext,
 937                                         $ntext,
 938                                         2
 939                                 );
 940
 941                                 // Log a warning in case the configuration value is set to not silently ignore it
 942                                 if ( $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' ) > 0 ) {
 943                                         wfLogWarning( '$wgWikiDiff2MovedParagraphDetectionCutoff is set but has no
 944                                                 effect since the used version of WikiDiff2 does not support it.' );
 945                                 }
 946                         }
 947
 948                         $text .= $this->debug( 'wikidiff2' );
 949
 950                         return $text;
 951                 } elseif ( $wgExternalDiffEngine !== false && is_executable( $wgExternalDiffEngine ) ) {
 952                         # Diff via the shell
 953                         $tmpDir = wfTempDir();
 954                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 955                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 956
 957                         $tempFile1 = fopen( $tempName1, "w" );
 958                         if ( !$tempFile1 ) {
 959                                 return false;
 960                         }
 961                         $tempFile2 = fopen( $tempName2, "w" );
 962                         if ( !$tempFile2 ) {
 963                                 return false;
 964                         }
 965                         fwrite( $tempFile1, $otext );
 966                         fwrite( $tempFile2, $ntext );
 967                         fclose( $tempFile1 );
 968                         fclose( $tempFile2 );
 969                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 970                         $difftext = wfShellExec( $cmd );
 971                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 972                         unlink( $tempName1 );
 973                         unlink( $tempName2 );
 974
 975                         return $difftext;
 976                 }
 977
 978                 # Native PHP diff
 979                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 980                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 981                 $diffs = new Diff( $ota, $nta );
 982                 $formatter = new TableDiffFormatter();
 983                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 984
 985                 return $difftext;
 986         }
 987
 988         /**
 989          * Generate a debug comment indicating diff generating time,
 990          * server node, and generator backend.
 991          *
 992          * @param string $generator : What diff engine was used
 993          *
 994          * @return string
 995          */
 996         protected function debug( $generator = "internal" ) {
 997                 global $wgShowHostnames;
 998                 if ( !$this->enableDebugComment ) {
 999                         return '';
1000                 }
1001                 $data = [ $generator ];
1002                 if ( $wgShowHostnames ) {
1003                         $data[] = wfHostname();
1004                 }
1005                 $data[] = wfTimestamp( TS_DB );
1006
1007                 return "<!-- diff generator: " .
1008                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1009                         " -->\n";
1010         }
1011
1012         /**
1013          * Replace line numbers with the text in the user's language
1014          *
1015          * @param string $text
1016          *
1017          * @return mixed
1018          */
1019         public function localiseLineNumbers( $text ) {
1020                 return preg_replace_callback(
1021                         '/<!--LINE (\d+)-->/',
1022                         [ $this, 'localiseLineNumbersCb' ],
1023                         $text
1024                 );
1025         }
1026
1027         public function localiseLineNumbersCb( $matches ) {
1028                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1029                         return '';
1030                 }
1031
1032                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1033         }
1034
1035         /**
1036          * If there are revisions between the ones being compared, return a note saying so.
1037          *
1038          * @return string
1039          */
1040         public function getMultiNotice() {
1041                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1042                         return '';
1043                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1044                         // Comparing two different pages? Count would be meaningless.
1045                         return '';
1046                 }
1047
1048                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1049                         $oldRev = $this->mNewRev; // flip
1050                         $newRev = $this->mOldRev; // flip
1051                 } else { // normal case
1052                         $oldRev = $this->mOldRev;
1053                         $newRev = $this->mNewRev;
1054                 }
1055
1056                 // Sanity: don't show the notice if too many rows must be scanned
1057                 // @todo show some special message for that case
1058                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1059                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1060                         $limit = 100; // use diff-multi-manyusers if too many users
1061                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1062                         $numUsers = count( $users );
1063
1064                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1065                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1066                         }
1067
1068                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1069                 }
1070
1071                 return ''; // nothing
1072         }
1073
1074         /**
1075          * Get a notice about how many intermediate edits and users there are
1076          *
1077          * @param int $numEdits
1078          * @param int $numUsers
1079          * @param int $limit
1080          *
1081          * @return string
1082          */
1083         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1084                 if ( $numUsers === 0 ) {
1085                         $msg = 'diff-multi-sameuser';
1086                 } elseif ( $numUsers > $limit ) {
1087                         $msg = 'diff-multi-manyusers';
1088                         $numUsers = $limit;
1089                 } else {
1090                         $msg = 'diff-multi-otherusers';
1091                 }
1092
1093                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1094         }
1095
1096         /**
1097          * Get a header for a specified revision.
1098          *
1099          * @param Revision $rev
1100          * @param string $complete 'complete' to get the header wrapped depending
1101          *        the visibility of the revision and a link to edit the page.
1102          *
1103          * @return string HTML fragment
1104          */
1105         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1106                 $lang = $this->getLanguage();
1107                 $user = $this->getUser();
1108                 $revtimestamp = $rev->getTimestamp();
1109                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1110                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1111                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1112
1113                 $header = $this->msg(
1114                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1115                         $timestamp,
1116                         $dateofrev,
1117                         $timeofrev
1118                 )->escaped();
1119
1120                 if ( $complete !== 'complete' ) {
1121                         return $header;
1122                 }
1123
1124                 $title = $rev->getTitle();
1125
1126                 $header = Linker::linkKnown( $title, $header, [],
1127                         [ 'oldid' => $rev->getId() ] );
1128
1129                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1130                         $editQuery = [ 'action' => 'edit' ];
1131                         if ( !$rev->isCurrent() ) {
1132                                 $editQuery['oldid'] = $rev->getId();
1133                         }
1134
1135                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1136                         $msg = $this->msg( $key )->escaped();
1137                         $editLink = $this->msg( 'parentheses' )->rawParams(
1138                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1139                         $header .= ' ' . Html::rawElement(
1140                                 'span',
1141                                 [ 'class' => 'mw-diff-edit' ],
1142                                 $editLink
1143                         );
1144                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1145                                 $header = Html::rawElement(
1146                                         'span',
1147                                         [ 'class' => 'history-deleted' ],
1148                                         $header
1149                                 );
1150                         }
1151                 } else {
1152                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1153                 }
1154
1155                 return $header;
1156         }
1157
1158         /**
1159          * Add the header to a diff body
1160          *
1161          * @param string $diff Diff body
1162          * @param string $otitle Old revision header
1163          * @param string $ntitle New revision header
1164          * @param string $multi Notice telling user that there are intermediate
1165          *   revisions between the ones being compared
1166          * @param string $notice Other notices, e.g. that user is viewing deleted content
1167          *
1168          * @return string
1169          */
1170         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1171                 // shared.css sets diff in interface language/dir, but the actual content
1172                 // is often in a different language, mostly the page content language/dir
1173                 $header = Html::openElement( 'table', [
1174                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1175                         'data-mw' => 'interface',
1176                 ] );
1177                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1178
1179                 if ( !$diff && !$otitle ) {
1180                         $header .= "
1181                         <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1182                         <td class=\"diff-ntitle\">{$ntitle}</td>
1183                         </tr>";
1184                         $multiColspan = 1;
1185                 } else {
1186                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1187                                 $header .= "
1188                                 <col class=\"diff-marker\" />
1189                                 <col class=\"diff-content\" />
1190                                 <col class=\"diff-marker\" />
1191                                 <col class=\"diff-content\" />";
1192                                 $colspan = 2;
1193                                 $multiColspan = 4;
1194                         } else {
1195                                 $colspan = 1;
1196                                 $multiColspan = 2;
1197                         }
1198                         if ( $otitle || $ntitle ) {
1199                                 $header .= "
1200                                 <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1201                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1202                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1203                                 </tr>";
1204                         }
1205                 }
1206
1207                 if ( $multi != '' ) {
1208                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1209                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1210                 }
1211                 if ( $notice != '' ) {
1212                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1213                                 "lang=\"{$userLang}\">{$notice}</td></tr>";
1214                 }
1215
1216                 return $header . $diff . "</table>";
1217         }
1218
1219         /**
1220          * Use specified text instead of loading from the database
1221          * @param Content $oldContent
1222          * @param Content $newContent
1223          * @since 1.21
1224          */
1225         public function setContent( Content $oldContent, Content $newContent ) {
1226                 $this->mOldContent = $oldContent;
1227                 $this->mNewContent = $newContent;
1228
1229                 $this->mTextLoaded = 2;
1230                 $this->mRevisionsLoaded = true;
1231         }
1232
1233         /**
1234          * Set the language in which the diff text is written
1235          * (Defaults to page content language).
1236          * @param Language|string $lang
1237          * @since 1.19
1238          */
1239         public function setTextLanguage( $lang ) {
1240                 $this->mDiffLang = wfGetLangObj( $lang );
1241         }
1242
1243         /**
1244          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1245          * to a pair of actual integers representing revision ids.
1246          *
1247          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1248          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1249          *
1250          * @return int[] List of two revision ids, older first, later second.
1251          *     Zero signifies invalid argument passed.
1252          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1253          */
1254         public function mapDiffPrevNext( $old, $new ) {
1255                 if ( $new === 'prev' ) {
1256                         // Show diff between revision $old and the previous one. Get previous one from DB.
1257                         $newid = intval( $old );
1258                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1259                 } elseif ( $new === 'next' ) {
1260                         // Show diff between revision $old and the next one. Get next one from DB.
1261                         $oldid = intval( $old );
1262                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1263                 } else {
1264                         $oldid = intval( $old );
1265                         $newid = intval( $new );
1266                 }
1267
1268                 return [ $oldid, $newid ];
1269         }
1270
1271         /**
1272          * Load revision IDs
1273          */
1274         private function loadRevisionIds() {
1275                 if ( $this->mRevisionsIdsLoaded ) {
1276                         return;
1277                 }
1278
1279                 $this->mRevisionsIdsLoaded = true;
1280
1281                 $old = $this->mOldid;
1282                 $new = $this->mNewid;
1283
1284                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1285                 if ( $new === 'next' && $this->mNewid === false ) {
1286                         # if no result, NewId points to the newest old revision. The only newer
1287                         # revision is cur, which is "0".
1288                         $this->mNewid = 0;
1289                 }
1290
1291                 Hooks::run(
1292                         'NewDifferenceEngine',
1293                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1294                 );
1295         }
1296
1297         /**
1298          * Load revision metadata for the specified articles. If newid is 0, then compare
1299          * the old article in oldid to the current article; if oldid is 0, then
1300          * compare the current article to the immediately previous one (ignoring the
1301          * value of newid).
1302          *
1303          * If oldid is false, leave the corresponding revision object set
1304          * to false. This is impossible via ordinary user input, and is provided for
1305          * API convenience.
1306          *
1307          * @return bool
1308          */
1309         public function loadRevisionData() {
1310                 if ( $this->mRevisionsLoaded ) {
1311                         return true;
1312                 }
1313
1314                 // Whether it succeeds or fails, we don't want to try again
1315                 $this->mRevisionsLoaded = true;
1316
1317                 $this->loadRevisionIds();
1318
1319                 // Load the new revision object
1320                 if ( $this->mNewid ) {
1321                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1322                 } else {
1323                         $this->mNewRev = Revision::newFromTitle(
1324                                 $this->getTitle(),
1325                                 false,
1326                                 Revision::READ_NORMAL
1327                         );
1328                 }
1329
1330                 if ( !$this->mNewRev instanceof Revision ) {
1331                         return false;
1332                 }
1333
1334                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1335                 $this->mNewid = $this->mNewRev->getId();
1336                 $this->mNewPage = $this->mNewRev->getTitle();
1337
1338                 // Load the old revision object
1339                 $this->mOldRev = false;
1340                 if ( $this->mOldid ) {
1341                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1342                 } elseif ( $this->mOldid === 0 ) {
1343                         $rev = $this->mNewRev->getPrevious();
1344                         if ( $rev ) {
1345                                 $this->mOldid = $rev->getId();
1346                                 $this->mOldRev = $rev;
1347                         } else {
1348                                 // No previous revision; mark to show as first-version only.
1349                                 $this->mOldid = false;
1350                                 $this->mOldRev = false;
1351                         }
1352                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1353
1354                 if ( is_null( $this->mOldRev ) ) {
1355                         return false;
1356                 }
1357
1358                 if ( $this->mOldRev ) {
1359                         $this->mOldPage = $this->mOldRev->getTitle();
1360                 }
1361
1362                 // Load tags information for both revisions
1363                 $dbr = wfGetDB( DB_REPLICA );
1364                 if ( $this->mOldid !== false ) {
1365                         $this->mOldTags = $dbr->selectField(
1366                                 'tag_summary',
1367                                 'ts_tags',
1368                                 [ 'ts_rev_id' => $this->mOldid ],
1369                                 __METHOD__
1370                         );
1371                 } else {
1372                         $this->mOldTags = false;
1373                 }
1374                 $this->mNewTags = $dbr->selectField(
1375                         'tag_summary',
1376                         'ts_tags',
1377                         [ 'ts_rev_id' => $this->mNewid ],
1378                         __METHOD__
1379                 );
1380
1381                 return true;
1382         }
1383
1384         /**
1385          * Load the text of the revisions, as well as revision data.
1386          *
1387          * @return bool
1388          */
1389         public function loadText() {
1390                 if ( $this->mTextLoaded == 2 ) {
1391                         return true;
1392                 }
1393
1394                 // Whether it succeeds or fails, we don't want to try again
1395                 $this->mTextLoaded = 2;
1396
1397                 if ( !$this->loadRevisionData() ) {
1398                         return false;
1399                 }
1400
1401                 if ( $this->mOldRev ) {
1402                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1403                         if ( $this->mOldContent === null ) {
1404                                 return false;
1405                         }
1406                 }
1407
1408                 if ( $this->mNewRev ) {
1409                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1410                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1411                         if ( $this->mNewContent === null ) {
1412                                 return false;
1413                         }
1414                 }
1415
1416                 return true;
1417         }
1418
1419         /**
1420          * Load the text of the new revision, not the old one
1421          *
1422          * @return bool
1423          */
1424         public function loadNewText() {
1425                 if ( $this->mTextLoaded >= 1 ) {
1426                         return true;
1427                 }
1428
1429                 $this->mTextLoaded = 1;
1430
1431                 if ( !$this->loadRevisionData() ) {
1432                         return false;
1433                 }
1434
1435                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1436
1437                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1438
1439                 return true;
1440         }
1441
1442 }