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 use MediaWiki\Shell\Shell;
  25
  26 /**
  27  * @todo document
  28  * @ingroup DifferenceEngine
  29  */
  30 class DifferenceEngine extends ContextSource {
  31         /**
  32          * Constant to indicate diff cache compatibility.
  33          * Bump this when changing the diff formatting in a way that
  34          * fixes important bugs or such to force cached diff views to
  35          * clear.
  36          */
  37         const DIFF_VERSION = '1.12';
  38
  39         /** @var int */
  40         public $mOldid;
  41
  42         /** @var int */
  43         public $mNewid;
  44
  45         private $mOldTags;
  46         private $mNewTags;
  47
  48         /** @var Content */
  49         public $mOldContent;
  50
  51         /** @var Content */
  52         public $mNewContent;
  53
  54         /** @var Language */
  55         protected $mDiffLang;
  56
  57         /** @var Title */
  58         public $mOldPage;
  59
  60         /** @var Title */
  61         public $mNewPage;
  62
  63         /** @var Revision */
  64         public $mOldRev;
  65
  66         /** @var Revision */
  67         public $mNewRev;
  68
  69         /** @var bool Have the revisions IDs been loaded */
  70         private $mRevisionsIdsLoaded = false;
  71
  72         /** @var bool Have the revisions been loaded */
  73         public $mRevisionsLoaded = false;
  74
  75         /** @var int How many text blobs have been loaded, 0, 1 or 2? */
  76         public $mTextLoaded = 0;
  77
  78         /** @var bool Was the diff fetched from cache? */
  79         public $mCacheHit = false;
  80
  81         /**
  82          * Set this to true to add debug info to the HTML output.
  83          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  84          * (T22601)
  85          */
  86         public $enableDebugComment = false;
  87
  88         /** @var bool If true, line X is not displayed when X is 1, for example
  89          *    to increase readability and conserve space with many small diffs.
  90          */
  91         protected $mReducedLineNumbers = false;
  92
  93         /** @var string Link to action=markpatrolled */
  94         protected $mMarkPatrolledLink = null;
  95
  96         /** @var bool Show rev_deleted content if allowed */
  97         protected $unhide = false;
  98
  99         /** @var bool Refresh the diff cache */
 100         protected $mRefreshCache = false;
 101
 102         /**#@-*/
 103
 104         /**
 105          * @param IContextSource $context Context to use, anything else will be ignored
 106          * @param int $old Old ID we want to show and diff with.
 107          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 108          * @param int $rcid Deprecated, no longer used!
 109          * @param bool $refreshCache If set, refreshes the diff cache
 110          * @param bool $unhide If set, allow viewing deleted revs
 111          */
 112         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 113                 $refreshCache = false, $unhide = false
 114         ) {
 115                 if ( $context instanceof IContextSource ) {
 116                         $this->setContext( $context );
 117                 }
 118
 119                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 120
 121                 $this->mOldid = $old;
 122                 $this->mNewid = $new;
 123                 $this->mRefreshCache = $refreshCache;
 124                 $this->unhide = $unhide;
 125         }
 126
 127         /**
 128          * @param bool $value
 129          */
 130         public function setReducedLineNumbers( $value = true ) {
 131                 $this->mReducedLineNumbers = $value;
 132         }
 133
 134         /**
 135          * @return Language
 136          */
 137         public function getDiffLang() {
 138                 if ( $this->mDiffLang === null ) {
 139                         # Default language in which the diff text is written.
 140                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 141                 }
 142
 143                 return $this->mDiffLang;
 144         }
 145
 146         /**
 147          * @return bool
 148          */
 149         public function wasCacheHit() {
 150                 return $this->mCacheHit;
 151         }
 152
 153         /**
 154          * @return int
 155          */
 156         public function getOldid() {
 157                 $this->loadRevisionIds();
 158
 159                 return $this->mOldid;
 160         }
 161
 162         /**
 163          * @return bool|int
 164          */
 165         public function getNewid() {
 166                 $this->loadRevisionIds();
 167
 168                 return $this->mNewid;
 169         }
 170
 171         /**
 172          * Look up a special:Undelete link to the given deleted revision id,
 173          * as a workaround for being unable to load deleted diffs in currently.
 174          *
 175          * @param int $id Revision ID
 176          *
 177          * @return string|bool Link HTML or false
 178          */
 179         public function deletedLink( $id ) {
 180                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 181                         $dbr = wfGetDB( DB_REPLICA );
 182                         $arQuery = Revision::getArchiveQueryInfo();
 183                         $row = $dbr->selectRow(
 184                                 $arQuery['tables'],
 185                                 array_merge( $arQuery['fields'], [ 'ar_namespace', 'ar_title' ] ),
 186                                 [ 'ar_rev_id' => $id ],
 187                                 __METHOD__,
 188                                 [],
 189                                 $arQuery['joins']
 190                         );
 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                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 608                         $this->loadNewText();
 609                         $out->setRevisionId( $this->mNewid );
 610                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 611                         $out->setArticleFlag( true );
 612
 613                         if ( !Hooks::run( 'ArticleContentViewCustom',
 614                                 [ $this->mNewContent, $this->mNewPage, $out ] )
 615                         ) {
 616                                 // Handled by extension
 617                         } else {
 618                                 // Normal page
 619                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 620                                         // If the Title stored in the context is the same as the one
 621                                         // of the new revision, we can use its associated WikiPage
 622                                         // object.
 623                                         $wikiPage = $this->getWikiPage();
 624                                 } else {
 625                                         // Otherwise we need to create our own WikiPage object
 626                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 627                                 }
 628
 629                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 630
 631                                 # WikiPage::getParserOutput() should not return false, but just in case
 632                                 if ( $parserOutput ) {
 633                                         // Allow extensions to change parser output here
 634                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput',
 635                                                 [ $this, $out, $parserOutput, $wikiPage ] )
 636                                         ) {
 637                                                 $out->addParserOutput( $parserOutput );
 638                                         }
 639                                 }
 640                         }
 641                 }
 642
 643                 // Allow extensions to optionally not show the final patrolled link
 644                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 645                         # Add redundant patrol link on bottom...
 646                         $out->addHTML( $this->markPatrolledLink() );
 647                 }
 648         }
 649
 650         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 651                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 652
 653                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 654                         $parserOptions->setEditSection( false );
 655                 }
 656
 657                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 658
 659                 return $parserOutput;
 660         }
 661
 662         /**
 663          * Get the diff text, send it to the OutputPage object
 664          * Returns false if the diff could not be generated, otherwise returns true
 665          *
 666          * @param string|bool $otitle Header for old text or false
 667          * @param string|bool $ntitle Header for new text or false
 668          * @param string $notice HTML between diff header and body
 669          *
 670          * @return bool
 671          */
 672         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 673                 // Allow extensions to affect the output here
 674                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 675
 676                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 677                 if ( $diff === false ) {
 678                         $this->showMissingRevision();
 679
 680                         return false;
 681                 } else {
 682                         $this->showDiffStyle();
 683                         $this->getOutput()->addHTML( $diff );
 684
 685                         return true;
 686                 }
 687         }
 688
 689         /**
 690          * Add style sheets for diff display.
 691          */
 692         public function showDiffStyle() {
 693                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 694         }
 695
 696         /**
 697          * Get complete diff table, including header
 698          *
 699          * @param string|bool $otitle Header for old text or false
 700          * @param string|bool $ntitle Header for new text or false
 701          * @param string $notice HTML between diff header and body
 702          *
 703          * @return mixed
 704          */
 705         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 706                 $body = $this->getDiffBody();
 707                 if ( $body === false ) {
 708                         return false;
 709                 }
 710
 711                 $multi = $this->getMultiNotice();
 712                 // Display a message when the diff is empty
 713                 if ( $body === '' ) {
 714                         $notice .= '<div class="mw-diff-empty">' .
 715                                 $this->msg( 'diff-empty' )->parse() .
 716                                 "</div>\n";
 717                 }
 718
 719                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 720         }
 721
 722         /**
 723          * Get the diff table body, without header
 724          *
 725          * @return mixed (string/false)
 726          */
 727         public function getDiffBody() {
 728                 $this->mCacheHit = true;
 729                 // Check if the diff should be hidden from this user
 730                 if ( !$this->loadRevisionData() ) {
 731                         return false;
 732                 } elseif ( $this->mOldRev &&
 733                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 734                 ) {
 735                         return false;
 736                 } elseif ( $this->mNewRev &&
 737                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 738                 ) {
 739                         return false;
 740                 }
 741                 // Short-circuit
 742                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 743                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 744                 ) {
 745                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 746                                 return '';
 747                         }
 748                 }
 749                 // Cacheable?
 750                 $key = false;
 751                 $cache = ObjectCache::getMainWANInstance();
 752                 if ( $this->mOldid && $this->mNewid ) {
 753                         // Check if subclass is still using the old way
 754                         // for backwards-compatibility
 755                         $key = $this->getDiffBodyCacheKey();
 756                         if ( $key === null ) {
 757                                 $key = call_user_func_array(
 758                                         [ $cache, 'makeKey' ],
 759                                         $this->getDiffBodyCacheKeyParams()
 760                                 );
 761                         }
 762
 763                         // Try cache
 764                         if ( !$this->mRefreshCache ) {
 765                                 $difftext = $cache->get( $key );
 766                                 if ( $difftext ) {
 767                                         wfIncrStats( 'diff_cache.hit' );
 768                                         $difftext = $this->localiseDiff( $difftext );
 769                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 770
 771                                         return $difftext;
 772                                 }
 773                         } // don't try to load but save the result
 774                 }
 775                 $this->mCacheHit = false;
 776
 777                 // Loadtext is permission safe, this just clears out the diff
 778                 if ( !$this->loadText() ) {
 779                         return false;
 780                 }
 781
 782                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 783
 784                 // Avoid PHP 7.1 warning from passing $this by reference
 785                 $diffEngine = $this;
 786
 787                 // Save to cache for 7 days
 788                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 789                         wfIncrStats( 'diff_cache.uncacheable' );
 790                 } elseif ( $key !== false && $difftext !== false ) {
 791                         wfIncrStats( 'diff_cache.miss' );
 792                         $cache->set( $key, $difftext, 7 * 86400 );
 793                 } else {
 794                         wfIncrStats( 'diff_cache.uncacheable' );
 795                 }
 796                 // localise line numbers and title attribute text
 797                 if ( $difftext !== false ) {
 798                         $difftext = $this->localiseDiff( $difftext );
 799                 }
 800
 801                 return $difftext;
 802         }
 803
 804         /**
 805          * Returns the cache key for diff body text or content.
 806          *
 807          * @deprecated since 1.31, use getDiffBodyCacheKeyParams() instead
 808          * @since 1.23
 809          *
 810          * @throws MWException
 811          * @return string|null
 812          */
 813         protected function getDiffBodyCacheKey() {
 814                 return null;
 815         }
 816
 817         /**
 818          * Get the cache key parameters
 819          *
 820          * Subclasses can replace the first element in the array to something
 821          * more specific to the type of diff (e.g. "inline-diff"), or append
 822          * if the cache should vary on more things. Overriding entirely should
 823          * be avoided.
 824          *
 825          * @since 1.31
 826          *
 827          * @return array
 828          * @throws MWException
 829          */
 830         protected function getDiffBodyCacheKeyParams() {
 831                 if ( !$this->mOldid || !$this->mNewid ) {
 832                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 833                 }
 834
 835                 $engine = $this->getEngine();
 836                 $params = [
 837                         'diff',
 838                         $engine,
 839                         self::DIFF_VERSION,
 840                         "old-{$this->mOldid}",
 841                         "rev-{$this->mNewid}"
 842                 ];
 843
 844                 if ( $engine === 'wikidiff2' ) {
 845                         $params[] = phpversion( 'wikidiff2' );
 846                         $params[] = $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' );
 847                 }
 848
 849                 return $params;
 850         }
 851
 852         /**
 853          * Generate a diff, no caching.
 854          *
 855          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 856          * serialization of the given Content objects. This will fail if $old or $new are not
 857          * instances of TextContent.
 858          *
 859          * Subclasses may override this to provide a different rendering for the diff,
 860          * perhaps taking advantage of the content's native form. This is required for all content
 861          * models that are not text based.
 862          *
 863          * @since 1.21
 864          *
 865          * @param Content $old Old content
 866          * @param Content $new New content
 867          *
 868          * @throws MWException If old or new content is not an instance of TextContent.
 869          * @return bool|string
 870          */
 871         public function generateContentDiffBody( Content $old, Content $new ) {
 872                 if ( !( $old instanceof TextContent ) ) {
 873                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 874                                 "override generateContentDiffBody to fix this." );
 875                 }
 876
 877                 if ( !( $new instanceof TextContent ) ) {
 878                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 879                                 . "override generateContentDiffBody to fix this." );
 880                 }
 881
 882                 $otext = $old->serialize();
 883                 $ntext = $new->serialize();
 884
 885                 return $this->generateTextDiffBody( $otext, $ntext );
 886         }
 887
 888         /**
 889          * Generate a diff, no caching
 890          *
 891          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 892          *
 893          * @param string $otext Old text, must be already segmented
 894          * @param string $ntext New text, must be already segmented
 895          *
 896          * @return bool|string
 897          */
 898         public function generateTextDiffBody( $otext, $ntext ) {
 899                 $diff = function () use ( $otext, $ntext ) {
 900                         $time = microtime( true );
 901
 902                         $result = $this->textDiff( $otext, $ntext );
 903
 904                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 905                         MediaWikiServices::getInstance()->getStatsdDataFactory()->timing( 'diff_time', $time );
 906                         // Log requests slower than 99th percentile
 907                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 908                                 wfDebugLog( 'diff',
 909                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 910                         }
 911
 912                         return $result;
 913                 };
 914
 915                 /**
 916                  * @param Status $status
 917                  * @throws FatalError
 918                  */
 919                 $error = function ( $status ) {
 920                         throw new FatalError( $status->getWikiText() );
 921                 };
 922
 923                 // Use PoolCounter if the diff looks like it can be expensive
 924                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 925                         $work = new PoolCounterWorkViaCallback( 'diff',
 926                                 md5( $otext ) . md5( $ntext ),
 927                                 [ 'doWork' => $diff, 'error' => $error ]
 928                         );
 929                         return $work->execute();
 930                 }
 931
 932                 return $diff();
 933         }
 934
 935         /**
 936          * Process $wgExternalDiffEngine and get a sane, usable engine
 937          *
 938          * @return bool|string 'wikidiff2', path to an executable, or false
 939          */
 940         private function getEngine() {
 941                 global $wgExternalDiffEngine;
 942                 // We use the global here instead of Config because we write to the value,
 943                 // and Config is not mutable.
 944                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 945                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 946                         $wgExternalDiffEngine = false;
 947                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 948                         // Same as above, but with no deprecation warnings
 949                         $wgExternalDiffEngine = false;
 950                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 951                         // And prevent people from shooting themselves in the foot...
 952                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 953                         $wgExternalDiffEngine = false;
 954                 }
 955
 956                 if ( is_string( $wgExternalDiffEngine ) && is_executable( $wgExternalDiffEngine ) ) {
 957                         return $wgExternalDiffEngine;
 958                 } elseif ( $wgExternalDiffEngine === false && function_exists( 'wikidiff2_do_diff' ) ) {
 959                         return 'wikidiff2';
 960                 } else {
 961                         // Native PHP
 962                         return false;
 963                 }
 964         }
 965
 966         /**
 967          * Generates diff, to be wrapped internally in a logging/instrumentation
 968          *
 969          * @param string $otext Old text, must be already segmented
 970          * @param string $ntext New text, must be already segmented
 971          * @return bool|string
 972          */
 973         protected function textDiff( $otext, $ntext ) {
 974                 global $wgContLang;
 975
 976                 $otext = str_replace( "\r\n", "\n", $otext );
 977                 $ntext = str_replace( "\r\n", "\n", $ntext );
 978
 979                 $engine = $this->getEngine();
 980
 981                 // Better external diff engine, the 2 may some day be dropped
 982                 // This one does the escaping and segmenting itself
 983                 if ( $engine === 'wikidiff2' ) {
 984                         $wikidiff2Version = phpversion( 'wikidiff2' );
 985                         if (
 986                                 $wikidiff2Version !== false &&
 987                                 version_compare( $wikidiff2Version, '1.5.0', '>=' )
 988                         ) {
 989                                 $text = wikidiff2_do_diff(
 990                                         $otext,
 991                                         $ntext,
 992                                         2,
 993                                         $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' )
 994                                 );
 995                         } else {
 996                                 // Don't pass the 4th parameter for compatibility with older versions of wikidiff2
 997                                 $text = wikidiff2_do_diff(
 998                                         $otext,
 999                                         $ntext,
1000                                         2
1001                                 );
1002
1003                                 // Log a warning in case the configuration value is set to not silently ignore it
1004                                 if ( $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' ) > 0 ) {
1005                                         wfLogWarning( '$wgWikiDiff2MovedParagraphDetectionCutoff is set but has no
1006                                                 effect since the used version of WikiDiff2 does not support it.' );
1007                                 }
1008                         }
1009
1010                         $text .= $this->debug( 'wikidiff2' );
1011
1012                         return $text;
1013                 } elseif ( $engine !== false ) {
1014                         # Diff via the shell
1015                         $tmpDir = wfTempDir();
1016                         $tempName1 = tempnam( $tmpDir, 'diff_' );
1017                         $tempName2 = tempnam( $tmpDir, 'diff_' );
1018
1019                         $tempFile1 = fopen( $tempName1, "w" );
1020                         if ( !$tempFile1 ) {
1021                                 return false;
1022                         }
1023                         $tempFile2 = fopen( $tempName2, "w" );
1024                         if ( !$tempFile2 ) {
1025                                 return false;
1026                         }
1027                         fwrite( $tempFile1, $otext );
1028                         fwrite( $tempFile2, $ntext );
1029                         fclose( $tempFile1 );
1030                         fclose( $tempFile2 );
1031                         $cmd = [ $engine, $tempName1, $tempName2 ];
1032                         $result = Shell::command( $cmd )
1033                                 ->execute();
1034                         $exitCode = $result->getExitCode();
1035                         if ( $exitCode !== 0 ) {
1036                                 throw new Exception( "External diff command returned code {$exitCode}. Stderr: "
1037                                         . wfEscapeWikiText( $result->getStderr() )
1038                                 );
1039                         }
1040                         $difftext = $result->getStdout();
1041                         $difftext .= $this->debug( "external $engine" );
1042                         unlink( $tempName1 );
1043                         unlink( $tempName2 );
1044
1045                         return $difftext;
1046                 }
1047
1048                 # Native PHP diff
1049                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
1050                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
1051                 $diffs = new Diff( $ota, $nta );
1052                 $formatter = new TableDiffFormatter();
1053                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
1054                 $difftext .= $this->debug( 'native PHP' );
1055
1056                 return $difftext;
1057         }
1058
1059         /**
1060          * Generate a debug comment indicating diff generating time,
1061          * server node, and generator backend.
1062          *
1063          * @param string $generator : What diff engine was used
1064          *
1065          * @return string
1066          */
1067         protected function debug( $generator = "internal" ) {
1068                 global $wgShowHostnames;
1069                 if ( !$this->enableDebugComment ) {
1070                         return '';
1071                 }
1072                 $data = [ $generator ];
1073                 if ( $wgShowHostnames ) {
1074                         $data[] = wfHostname();
1075                 }
1076                 $data[] = wfTimestamp( TS_DB );
1077
1078                 return "<!-- diff generator: " .
1079                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1080                         " -->\n";
1081         }
1082
1083         /**
1084          * Localise diff output
1085          *
1086          * @param string $text
1087          * @return string
1088          */
1089         private function localiseDiff( $text ) {
1090                 $text = $this->localiseLineNumbers( $text );
1091                 if ( $this->getEngine() === 'wikidiff2' &&
1092                         version_compare( phpversion( 'wikidiff2' ), '1.5.1', '>=' )
1093                 ) {
1094                         $text = $this->addLocalisedTitleTooltips( $text );
1095                 }
1096                 return $text;
1097         }
1098
1099         /**
1100          * Replace line numbers with the text in the user's language
1101          *
1102          * @param string $text
1103          *
1104          * @return mixed
1105          */
1106         public function localiseLineNumbers( $text ) {
1107                 return preg_replace_callback(
1108                         '/<!--LINE (\d+)-->/',
1109                         [ $this, 'localiseLineNumbersCb' ],
1110                         $text
1111                 );
1112         }
1113
1114         public function localiseLineNumbersCb( $matches ) {
1115                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1116                         return '';
1117                 }
1118
1119                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1120         }
1121
1122         /**
1123          * Add title attributes for tooltips on moved paragraph indicators
1124          *
1125          * @param string $text
1126          * @return string
1127          */
1128         private function addLocalisedTitleTooltips( $text ) {
1129                 return preg_replace_callback(
1130                         '/class="mw-diff-movedpara-(left|old)"/',
1131                         [ $this, 'addLocalisedTitleTooltipsCb' ],
1132                         $text
1133                 );
1134         }
1135
1136         /**
1137          * @param array $matches
1138          * @return string
1139          */
1140         private function addLocalisedTitleTooltipsCb( array $matches ) {
1141                 $key = $matches[1] === 'right' ?
1142                         'diff-paragraph-moved-toold' :
1143                         'diff-paragraph-moved-tonew';
1144                 return $matches[0] . ' title="' . $this->msg( $key )->escaped() . '"';
1145         }
1146
1147         /**
1148          * If there are revisions between the ones being compared, return a note saying so.
1149          *
1150          * @return string
1151          */
1152         public function getMultiNotice() {
1153                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1154                         return '';
1155                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1156                         // Comparing two different pages? Count would be meaningless.
1157                         return '';
1158                 }
1159
1160                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1161                         $oldRev = $this->mNewRev; // flip
1162                         $newRev = $this->mOldRev; // flip
1163                 } else { // normal case
1164                         $oldRev = $this->mOldRev;
1165                         $newRev = $this->mNewRev;
1166                 }
1167
1168                 // Sanity: don't show the notice if too many rows must be scanned
1169                 // @todo show some special message for that case
1170                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1171                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1172                         $limit = 100; // use diff-multi-manyusers if too many users
1173                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1174                         $numUsers = count( $users );
1175
1176                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1177                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1178                         }
1179
1180                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1181                 }
1182
1183                 return ''; // nothing
1184         }
1185
1186         /**
1187          * Get a notice about how many intermediate edits and users there are
1188          *
1189          * @param int $numEdits
1190          * @param int $numUsers
1191          * @param int $limit
1192          *
1193          * @return string
1194          */
1195         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1196                 if ( $numUsers === 0 ) {
1197                         $msg = 'diff-multi-sameuser';
1198                 } elseif ( $numUsers > $limit ) {
1199                         $msg = 'diff-multi-manyusers';
1200                         $numUsers = $limit;
1201                 } else {
1202                         $msg = 'diff-multi-otherusers';
1203                 }
1204
1205                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1206         }
1207
1208         /**
1209          * Get a header for a specified revision.
1210          *
1211          * @param Revision $rev
1212          * @param string $complete 'complete' to get the header wrapped depending
1213          *        the visibility of the revision and a link to edit the page.
1214          *
1215          * @return string HTML fragment
1216          */
1217         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1218                 $lang = $this->getLanguage();
1219                 $user = $this->getUser();
1220                 $revtimestamp = $rev->getTimestamp();
1221                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1222                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1223                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1224
1225                 $header = $this->msg(
1226                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1227                         $timestamp,
1228                         $dateofrev,
1229                         $timeofrev
1230                 )->escaped();
1231
1232                 if ( $complete !== 'complete' ) {
1233                         return $header;
1234                 }
1235
1236                 $title = $rev->getTitle();
1237
1238                 $header = Linker::linkKnown( $title, $header, [],
1239                         [ 'oldid' => $rev->getId() ] );
1240
1241                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1242                         $editQuery = [ 'action' => 'edit' ];
1243                         if ( !$rev->isCurrent() ) {
1244                                 $editQuery['oldid'] = $rev->getId();
1245                         }
1246
1247                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1248                         $msg = $this->msg( $key )->escaped();
1249                         $editLink = $this->msg( 'parentheses' )->rawParams(
1250                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1251                         $header .= ' ' . Html::rawElement(
1252                                 'span',
1253                                 [ 'class' => 'mw-diff-edit' ],
1254                                 $editLink
1255                         );
1256                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1257                                 $header = Html::rawElement(
1258                                         'span',
1259                                         [ 'class' => 'history-deleted' ],
1260                                         $header
1261                                 );
1262                         }
1263                 } else {
1264                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1265                 }
1266
1267                 return $header;
1268         }
1269
1270         /**
1271          * Add the header to a diff body
1272          *
1273          * @param string $diff Diff body
1274          * @param string $otitle Old revision header
1275          * @param string $ntitle New revision header
1276          * @param string $multi Notice telling user that there are intermediate
1277          *   revisions between the ones being compared
1278          * @param string $notice Other notices, e.g. that user is viewing deleted content
1279          *
1280          * @return string
1281          */
1282         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1283                 // shared.css sets diff in interface language/dir, but the actual content
1284                 // is often in a different language, mostly the page content language/dir
1285                 $header = Html::openElement( 'table', [
1286                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1287                         'data-mw' => 'interface',
1288                 ] );
1289                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1290
1291                 if ( !$diff && !$otitle ) {
1292                         $header .= "
1293                         <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1294                         <td class=\"diff-ntitle\">{$ntitle}</td>
1295                         </tr>";
1296                         $multiColspan = 1;
1297                 } else {
1298                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1299                                 $header .= "
1300                                 <col class=\"diff-marker\" />
1301                                 <col class=\"diff-content\" />
1302                                 <col class=\"diff-marker\" />
1303                                 <col class=\"diff-content\" />";
1304                                 $colspan = 2;
1305                                 $multiColspan = 4;
1306                         } else {
1307                                 $colspan = 1;
1308                                 $multiColspan = 2;
1309                         }
1310                         if ( $otitle || $ntitle ) {
1311                                 $header .= "
1312                                 <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1313                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1314                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1315                                 </tr>";
1316                         }
1317                 }
1318
1319                 if ( $multi != '' ) {
1320                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1321                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1322                 }
1323                 if ( $notice != '' ) {
1324                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1325                                 "lang=\"{$userLang}\">{$notice}</td></tr>";
1326                 }
1327
1328                 return $header . $diff . "</table>";
1329         }
1330
1331         /**
1332          * Use specified text instead of loading from the database
1333          * @param Content $oldContent
1334          * @param Content $newContent
1335          * @since 1.21
1336          */
1337         public function setContent( Content $oldContent, Content $newContent ) {
1338                 $this->mOldContent = $oldContent;
1339                 $this->mNewContent = $newContent;
1340
1341                 $this->mTextLoaded = 2;
1342                 $this->mRevisionsLoaded = true;
1343         }
1344
1345         /**
1346          * Set the language in which the diff text is written
1347          * (Defaults to page content language).
1348          * @param Language|string $lang
1349          * @since 1.19
1350          */
1351         public function setTextLanguage( $lang ) {
1352                 $this->mDiffLang = wfGetLangObj( $lang );
1353         }
1354
1355         /**
1356          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1357          * to a pair of actual integers representing revision ids.
1358          *
1359          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1360          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1361          *
1362          * @return int[] List of two revision ids, older first, later second.
1363          *     Zero signifies invalid argument passed.
1364          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1365          */
1366         public function mapDiffPrevNext( $old, $new ) {
1367                 if ( $new === 'prev' ) {
1368                         // Show diff between revision $old and the previous one. Get previous one from DB.
1369                         $newid = intval( $old );
1370                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1371                 } elseif ( $new === 'next' ) {
1372                         // Show diff between revision $old and the next one. Get next one from DB.
1373                         $oldid = intval( $old );
1374                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1375                 } else {
1376                         $oldid = intval( $old );
1377                         $newid = intval( $new );
1378                 }
1379
1380                 return [ $oldid, $newid ];
1381         }
1382
1383         /**
1384          * Load revision IDs
1385          */
1386         private function loadRevisionIds() {
1387                 if ( $this->mRevisionsIdsLoaded ) {
1388                         return;
1389                 }
1390
1391                 $this->mRevisionsIdsLoaded = true;
1392
1393                 $old = $this->mOldid;
1394                 $new = $this->mNewid;
1395
1396                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1397                 if ( $new === 'next' && $this->mNewid === false ) {
1398                         # if no result, NewId points to the newest old revision. The only newer
1399                         # revision is cur, which is "0".
1400                         $this->mNewid = 0;
1401                 }
1402
1403                 Hooks::run(
1404                         'NewDifferenceEngine',
1405                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1406                 );
1407         }
1408
1409         /**
1410          * Load revision metadata for the specified articles. If newid is 0, then compare
1411          * the old article in oldid to the current article; if oldid is 0, then
1412          * compare the current article to the immediately previous one (ignoring the
1413          * value of newid).
1414          *
1415          * If oldid is false, leave the corresponding revision object set
1416          * to false. This is impossible via ordinary user input, and is provided for
1417          * API convenience.
1418          *
1419          * @return bool
1420          */
1421         public function loadRevisionData() {
1422                 if ( $this->mRevisionsLoaded ) {
1423                         return true;
1424                 }
1425
1426                 // Whether it succeeds or fails, we don't want to try again
1427                 $this->mRevisionsLoaded = true;
1428
1429                 $this->loadRevisionIds();
1430
1431                 // Load the new revision object
1432                 if ( $this->mNewid ) {
1433                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1434                 } else {
1435                         $this->mNewRev = Revision::newFromTitle(
1436                                 $this->getTitle(),
1437                                 false,
1438                                 Revision::READ_NORMAL
1439                         );
1440                 }
1441
1442                 if ( !$this->mNewRev instanceof Revision ) {
1443                         return false;
1444                 }
1445
1446                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1447                 $this->mNewid = $this->mNewRev->getId();
1448                 $this->mNewPage = $this->mNewRev->getTitle();
1449
1450                 // Load the old revision object
1451                 $this->mOldRev = false;
1452                 if ( $this->mOldid ) {
1453                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1454                 } elseif ( $this->mOldid === 0 ) {
1455                         $rev = $this->mNewRev->getPrevious();
1456                         if ( $rev ) {
1457                                 $this->mOldid = $rev->getId();
1458                                 $this->mOldRev = $rev;
1459                         } else {
1460                                 // No previous revision; mark to show as first-version only.
1461                                 $this->mOldid = false;
1462                                 $this->mOldRev = false;
1463                         }
1464                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1465
1466                 if ( is_null( $this->mOldRev ) ) {
1467                         return false;
1468                 }
1469
1470                 if ( $this->mOldRev ) {
1471                         $this->mOldPage = $this->mOldRev->getTitle();
1472                 }
1473
1474                 // Load tags information for both revisions
1475                 $dbr = wfGetDB( DB_REPLICA );
1476                 if ( $this->mOldid !== false ) {
1477                         $this->mOldTags = $dbr->selectField(
1478                                 'tag_summary',
1479                                 'ts_tags',
1480                                 [ 'ts_rev_id' => $this->mOldid ],
1481                                 __METHOD__
1482                         );
1483                 } else {
1484                         $this->mOldTags = false;
1485                 }
1486                 $this->mNewTags = $dbr->selectField(
1487                         'tag_summary',
1488                         'ts_tags',
1489                         [ 'ts_rev_id' => $this->mNewid ],
1490                         __METHOD__
1491                 );
1492
1493                 return true;
1494         }
1495
1496         /**
1497          * Load the text of the revisions, as well as revision data.
1498          *
1499          * @return bool
1500          */
1501         public function loadText() {
1502                 if ( $this->mTextLoaded == 2 ) {
1503                         return true;
1504                 }
1505
1506                 // Whether it succeeds or fails, we don't want to try again
1507                 $this->mTextLoaded = 2;
1508
1509                 if ( !$this->loadRevisionData() ) {
1510                         return false;
1511                 }
1512
1513                 if ( $this->mOldRev ) {
1514                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1515                         if ( $this->mOldContent === null ) {
1516                                 return false;
1517                         }
1518                 }
1519
1520                 if ( $this->mNewRev ) {
1521                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1522                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1523                         if ( $this->mNewContent === null ) {
1524                                 return false;
1525                         }
1526                 }
1527
1528                 return true;
1529         }
1530
1531         /**
1532          * Load the text of the new revision, not the old one
1533          *
1534          * @return bool
1535          */
1536         public function loadNewText() {
1537                 if ( $this->mTextLoaded >= 1 ) {
1538                         return true;
1539                 }
1540
1541                 $this->mTextLoaded = 1;
1542
1543                 if ( !$this->loadRevisionData() ) {
1544                         return false;
1545                 }
1546
1547                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1548
1549                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1550
1551                 return true;
1552         }
1553
1554 }