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;
 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' => RecentChange::PRC_UNPATROLLED
 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 ( $user->isAllowed( 'writeapi' ) ) {
 568                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 569                                 }
 570
 571                                 return [
 572                                         'rcid' => $rcid,
 573                                 ];
 574                         }
 575                 }
 576
 577                 // No mark as patrolled link applicable
 578                 return false;
 579         }
 580
 581         /**
 582          * @param Revision $rev
 583          *
 584          * @return string
 585          */
 586         protected function revisionDeleteLink( $rev ) {
 587                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 588                 if ( $link !== '' ) {
 589                         $link = '&#160;&#160;&#160;' . $link . ' ';
 590                 }
 591
 592                 return $link;
 593         }
 594
 595         /**
 596          * Show the new revision of the page.
 597          */
 598         public function renderNewRevision() {
 599                 $out = $this->getOutput();
 600                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 601                 # Add "current version as of X" title
 602                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 603                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 604                 # Page content may be handled by a hooked call instead...
 605                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 606                         $this->loadNewText();
 607                         $out->setRevisionId( $this->mNewid );
 608                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 609                         $out->setArticleFlag( true );
 610
 611                         if ( !Hooks::run( 'ArticleContentViewCustom',
 612                                 [ $this->mNewContent, $this->mNewPage, $out ] )
 613                         ) {
 614                                 // Handled by extension
 615                         } else {
 616                                 // Normal page
 617                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 618                                         // If the Title stored in the context is the same as the one
 619                                         // of the new revision, we can use its associated WikiPage
 620                                         // object.
 621                                         $wikiPage = $this->getWikiPage();
 622                                 } else {
 623                                         // Otherwise we need to create our own WikiPage object
 624                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 625                                 }
 626
 627                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 628
 629                                 # WikiPage::getParserOutput() should not return false, but just in case
 630                                 if ( $parserOutput ) {
 631                                         // Allow extensions to change parser output here
 632                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput',
 633                                                 [ $this, $out, $parserOutput, $wikiPage ] )
 634                                         ) {
 635                                                 $out->addParserOutput( $parserOutput, [
 636                                                         'enableSectionEditLinks' => $this->mNewRev->isCurrent()
 637                                                                 && $this->mNewRev->getTitle()->quickUserCan( 'edit', $this->getUser() ),
 638                                                 ] );
 639                                         }
 640                                 }
 641                         }
 642                 }
 643
 644                 // Allow extensions to optionally not show the final patrolled link
 645                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 646                         # Add redundant patrol link on bottom...
 647                         $out->addHTML( $this->markPatrolledLink() );
 648                 }
 649         }
 650
 651         /**
 652          * @param WikiPage $page
 653          * @param Revision $rev
 654          *
 655          * @return ParserOutput|bool False if the revision was not found
 656          */
 657         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 658                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 659                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 660
 661                 return $parserOutput;
 662         }
 663
 664         /**
 665          * Get the diff text, send it to the OutputPage object
 666          * Returns false if the diff could not be generated, otherwise returns true
 667          *
 668          * @param string|bool $otitle Header for old text or false
 669          * @param string|bool $ntitle Header for new text or false
 670          * @param string $notice HTML between diff header and body
 671          *
 672          * @return bool
 673          */
 674         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 675                 // Allow extensions to affect the output here
 676                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 677
 678                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 679                 if ( $diff === false ) {
 680                         $this->showMissingRevision();
 681
 682                         return false;
 683                 } else {
 684                         $this->showDiffStyle();
 685                         $this->getOutput()->addHTML( $diff );
 686
 687                         return true;
 688                 }
 689         }
 690
 691         /**
 692          * Add style sheets for diff display.
 693          */
 694         public function showDiffStyle() {
 695                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 696         }
 697
 698         /**
 699          * Get complete diff table, including header
 700          *
 701          * @param string|bool $otitle Header for old text or false
 702          * @param string|bool $ntitle Header for new text or false
 703          * @param string $notice HTML between diff header and body
 704          *
 705          * @return mixed
 706          */
 707         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 708                 $body = $this->getDiffBody();
 709                 if ( $body === false ) {
 710                         return false;
 711                 }
 712
 713                 $multi = $this->getMultiNotice();
 714                 // Display a message when the diff is empty
 715                 if ( $body === '' ) {
 716                         $notice .= '<div class="mw-diff-empty">' .
 717                                 $this->msg( 'diff-empty' )->parse() .
 718                                 "</div>\n";
 719                 }
 720
 721                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 722         }
 723
 724         /**
 725          * Get the diff table body, without header
 726          *
 727          * @return mixed (string/false)
 728          */
 729         public function getDiffBody() {
 730                 $this->mCacheHit = true;
 731                 // Check if the diff should be hidden from this user
 732                 if ( !$this->loadRevisionData() ) {
 733                         return false;
 734                 } elseif ( $this->mOldRev &&
 735                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 736                 ) {
 737                         return false;
 738                 } elseif ( $this->mNewRev &&
 739                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 740                 ) {
 741                         return false;
 742                 }
 743                 // Short-circuit
 744                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 745                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 746                 ) {
 747                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 748                                 return '';
 749                         }
 750                 }
 751                 // Cacheable?
 752                 $key = false;
 753                 $cache = ObjectCache::getMainWANInstance();
 754                 if ( $this->mOldid && $this->mNewid ) {
 755                         // Check if subclass is still using the old way
 756                         // for backwards-compatibility
 757                         $key = $this->getDiffBodyCacheKey();
 758                         if ( $key === null ) {
 759                                 $key = call_user_func_array(
 760                                         [ $cache, 'makeKey' ],
 761                                         $this->getDiffBodyCacheKeyParams()
 762                                 );
 763                         }
 764
 765                         // Try cache
 766                         if ( !$this->mRefreshCache ) {
 767                                 $difftext = $cache->get( $key );
 768                                 if ( $difftext ) {
 769                                         wfIncrStats( 'diff_cache.hit' );
 770                                         $difftext = $this->localiseDiff( $difftext );
 771                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 772
 773                                         return $difftext;
 774                                 }
 775                         } // don't try to load but save the result
 776                 }
 777                 $this->mCacheHit = false;
 778
 779                 // Loadtext is permission safe, this just clears out the diff
 780                 if ( !$this->loadText() ) {
 781                         return false;
 782                 }
 783
 784                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 785
 786                 // Avoid PHP 7.1 warning from passing $this by reference
 787                 $diffEngine = $this;
 788
 789                 // Save to cache for 7 days
 790                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 791                         wfIncrStats( 'diff_cache.uncacheable' );
 792                 } elseif ( $key !== false && $difftext !== false ) {
 793                         wfIncrStats( 'diff_cache.miss' );
 794                         $cache->set( $key, $difftext, 7 * 86400 );
 795                 } else {
 796                         wfIncrStats( 'diff_cache.uncacheable' );
 797                 }
 798                 // localise line numbers and title attribute text
 799                 if ( $difftext !== false ) {
 800                         $difftext = $this->localiseDiff( $difftext );
 801                 }
 802
 803                 return $difftext;
 804         }
 805
 806         /**
 807          * Returns the cache key for diff body text or content.
 808          *
 809          * @deprecated since 1.31, use getDiffBodyCacheKeyParams() instead
 810          * @since 1.23
 811          *
 812          * @throws MWException
 813          * @return string|null
 814          */
 815         protected function getDiffBodyCacheKey() {
 816                 return null;
 817         }
 818
 819         /**
 820          * Get the cache key parameters
 821          *
 822          * Subclasses can replace the first element in the array to something
 823          * more specific to the type of diff (e.g. "inline-diff"), or append
 824          * if the cache should vary on more things. Overriding entirely should
 825          * be avoided.
 826          *
 827          * @since 1.31
 828          *
 829          * @return array
 830          * @throws MWException
 831          */
 832         protected function getDiffBodyCacheKeyParams() {
 833                 if ( !$this->mOldid || !$this->mNewid ) {
 834                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 835                 }
 836
 837                 $engine = $this->getEngine();
 838                 $params = [
 839                         'diff',
 840                         $engine,
 841                         self::DIFF_VERSION,
 842                         "old-{$this->mOldid}",
 843                         "rev-{$this->mNewid}"
 844                 ];
 845
 846                 if ( $engine === 'wikidiff2' ) {
 847                         $params[] = phpversion( 'wikidiff2' );
 848                         $params[] = $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' );
 849                 }
 850
 851                 return $params;
 852         }
 853
 854         /**
 855          * Generate a diff, no caching.
 856          *
 857          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 858          * serialization of the given Content objects. This will fail if $old or $new are not
 859          * instances of TextContent.
 860          *
 861          * Subclasses may override this to provide a different rendering for the diff,
 862          * perhaps taking advantage of the content's native form. This is required for all content
 863          * models that are not text based.
 864          *
 865          * @since 1.21
 866          *
 867          * @param Content $old Old content
 868          * @param Content $new New content
 869          *
 870          * @throws MWException If old or new content is not an instance of TextContent.
 871          * @return bool|string
 872          */
 873         public function generateContentDiffBody( Content $old, Content $new ) {
 874                 if ( !( $old instanceof TextContent ) ) {
 875                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 876                                 "override generateContentDiffBody to fix this." );
 877                 }
 878
 879                 if ( !( $new instanceof TextContent ) ) {
 880                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 881                                 . "override generateContentDiffBody to fix this." );
 882                 }
 883
 884                 $otext = $old->serialize();
 885                 $ntext = $new->serialize();
 886
 887                 return $this->generateTextDiffBody( $otext, $ntext );
 888         }
 889
 890         /**
 891          * Generate a diff, no caching
 892          *
 893          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 894          *
 895          * @param string $otext Old text, must be already segmented
 896          * @param string $ntext New text, must be already segmented
 897          *
 898          * @return bool|string
 899          */
 900         public function generateTextDiffBody( $otext, $ntext ) {
 901                 $diff = function () use ( $otext, $ntext ) {
 902                         $time = microtime( true );
 903
 904                         $result = $this->textDiff( $otext, $ntext );
 905
 906                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 907                         MediaWikiServices::getInstance()->getStatsdDataFactory()->timing( 'diff_time', $time );
 908                         // Log requests slower than 99th percentile
 909                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 910                                 wfDebugLog( 'diff',
 911                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 912                         }
 913
 914                         return $result;
 915                 };
 916
 917                 /**
 918                  * @param Status $status
 919                  * @throws FatalError
 920                  */
 921                 $error = function ( $status ) {
 922                         throw new FatalError( $status->getWikiText() );
 923                 };
 924
 925                 // Use PoolCounter if the diff looks like it can be expensive
 926                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 927                         $work = new PoolCounterWorkViaCallback( 'diff',
 928                                 md5( $otext ) . md5( $ntext ),
 929                                 [ 'doWork' => $diff, 'error' => $error ]
 930                         );
 931                         return $work->execute();
 932                 }
 933
 934                 return $diff();
 935         }
 936
 937         /**
 938          * Process $wgExternalDiffEngine and get a sane, usable engine
 939          *
 940          * @return bool|string 'wikidiff2', path to an executable, or false
 941          */
 942         private function getEngine() {
 943                 global $wgExternalDiffEngine;
 944                 // We use the global here instead of Config because we write to the value,
 945                 // and Config is not mutable.
 946                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 947                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 948                         $wgExternalDiffEngine = false;
 949                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 950                         // Same as above, but with no deprecation warnings
 951                         $wgExternalDiffEngine = false;
 952                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 953                         // And prevent people from shooting themselves in the foot...
 954                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 955                         $wgExternalDiffEngine = false;
 956                 }
 957
 958                 if ( is_string( $wgExternalDiffEngine ) && is_executable( $wgExternalDiffEngine ) ) {
 959                         return $wgExternalDiffEngine;
 960                 } elseif ( $wgExternalDiffEngine === false && function_exists( 'wikidiff2_do_diff' ) ) {
 961                         return 'wikidiff2';
 962                 } else {
 963                         // Native PHP
 964                         return false;
 965                 }
 966         }
 967
 968         /**
 969          * Generates diff, to be wrapped internally in a logging/instrumentation
 970          *
 971          * @param string $otext Old text, must be already segmented
 972          * @param string $ntext New text, must be already segmented
 973          * @return bool|string
 974          */
 975         protected function textDiff( $otext, $ntext ) {
 976                 global $wgContLang;
 977
 978                 $otext = str_replace( "\r\n", "\n", $otext );
 979                 $ntext = str_replace( "\r\n", "\n", $ntext );
 980
 981                 $engine = $this->getEngine();
 982
 983                 // Better external diff engine, the 2 may some day be dropped
 984                 // This one does the escaping and segmenting itself
 985                 if ( $engine === 'wikidiff2' ) {
 986                         $wikidiff2Version = phpversion( 'wikidiff2' );
 987                         if (
 988                                 $wikidiff2Version !== false &&
 989                                 version_compare( $wikidiff2Version, '1.5.0', '>=' )
 990                         ) {
 991                                 $text = wikidiff2_do_diff(
 992                                         $otext,
 993                                         $ntext,
 994                                         2,
 995                                         $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' )
 996                                 );
 997                         } else {
 998                                 // Don't pass the 4th parameter for compatibility with older versions of wikidiff2
 999                                 $text = wikidiff2_do_diff(
1000                                         $otext,
1001                                         $ntext,
1002                                         2
1003                                 );
1004
1005                                 // Log a warning in case the configuration value is set to not silently ignore it
1006                                 if ( $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' ) > 0 ) {
1007                                         wfLogWarning( '$wgWikiDiff2MovedParagraphDetectionCutoff is set but has no
1008                                                 effect since the used version of WikiDiff2 does not support it.' );
1009                                 }
1010                         }
1011
1012                         $text .= $this->debug( 'wikidiff2' );
1013
1014                         return $text;
1015                 } elseif ( $engine !== false ) {
1016                         # Diff via the shell
1017                         $tmpDir = wfTempDir();
1018                         $tempName1 = tempnam( $tmpDir, 'diff_' );
1019                         $tempName2 = tempnam( $tmpDir, 'diff_' );
1020
1021                         $tempFile1 = fopen( $tempName1, "w" );
1022                         if ( !$tempFile1 ) {
1023                                 return false;
1024                         }
1025                         $tempFile2 = fopen( $tempName2, "w" );
1026                         if ( !$tempFile2 ) {
1027                                 return false;
1028                         }
1029                         fwrite( $tempFile1, $otext );
1030                         fwrite( $tempFile2, $ntext );
1031                         fclose( $tempFile1 );
1032                         fclose( $tempFile2 );
1033                         $cmd = [ $engine, $tempName1, $tempName2 ];
1034                         $result = Shell::command( $cmd )
1035                                 ->execute();
1036                         $exitCode = $result->getExitCode();
1037                         if ( $exitCode !== 0 ) {
1038                                 throw new Exception( "External diff command returned code {$exitCode}. Stderr: "
1039                                         . wfEscapeWikiText( $result->getStderr() )
1040                                 );
1041                         }
1042                         $difftext = $result->getStdout();
1043                         $difftext .= $this->debug( "external $engine" );
1044                         unlink( $tempName1 );
1045                         unlink( $tempName2 );
1046
1047                         return $difftext;
1048                 }
1049
1050                 # Native PHP diff
1051                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
1052                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
1053                 $diffs = new Diff( $ota, $nta );
1054                 $formatter = new TableDiffFormatter();
1055                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
1056                 $difftext .= $this->debug( 'native PHP' );
1057
1058                 return $difftext;
1059         }
1060
1061         /**
1062          * Generate a debug comment indicating diff generating time,
1063          * server node, and generator backend.
1064          *
1065          * @param string $generator : What diff engine was used
1066          *
1067          * @return string
1068          */
1069         protected function debug( $generator = "internal" ) {
1070                 global $wgShowHostnames;
1071                 if ( !$this->enableDebugComment ) {
1072                         return '';
1073                 }
1074                 $data = [ $generator ];
1075                 if ( $wgShowHostnames ) {
1076                         $data[] = wfHostname();
1077                 }
1078                 $data[] = wfTimestamp( TS_DB );
1079
1080                 return "<!-- diff generator: " .
1081                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1082                         " -->\n";
1083         }
1084
1085         /**
1086          * Localise diff output
1087          *
1088          * @param string $text
1089          * @return string
1090          */
1091         private function localiseDiff( $text ) {
1092                 $text = $this->localiseLineNumbers( $text );
1093                 if ( $this->getEngine() === 'wikidiff2' &&
1094                         version_compare( phpversion( 'wikidiff2' ), '1.5.1', '>=' )
1095                 ) {
1096                         $text = $this->addLocalisedTitleTooltips( $text );
1097                 }
1098                 return $text;
1099         }
1100
1101         /**
1102          * Replace line numbers with the text in the user's language
1103          *
1104          * @param string $text
1105          *
1106          * @return mixed
1107          */
1108         public function localiseLineNumbers( $text ) {
1109                 return preg_replace_callback(
1110                         '/<!--LINE (\d+)-->/',
1111                         [ $this, 'localiseLineNumbersCb' ],
1112                         $text
1113                 );
1114         }
1115
1116         public function localiseLineNumbersCb( $matches ) {
1117                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1118                         return '';
1119                 }
1120
1121                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1122         }
1123
1124         /**
1125          * Add title attributes for tooltips on moved paragraph indicators
1126          *
1127          * @param string $text
1128          * @return string
1129          */
1130         private function addLocalisedTitleTooltips( $text ) {
1131                 return preg_replace_callback(
1132                         '/class="mw-diff-movedpara-(left|right)"/',
1133                         [ $this, 'addLocalisedTitleTooltipsCb' ],
1134                         $text
1135                 );
1136         }
1137
1138         /**
1139          * @param array $matches
1140          * @return string
1141          */
1142         private function addLocalisedTitleTooltipsCb( array $matches ) {
1143                 $key = $matches[1] === 'right' ?
1144                         'diff-paragraph-moved-toold' :
1145                         'diff-paragraph-moved-tonew';
1146                 return $matches[0] . ' title="' . $this->msg( $key )->escaped() . '"';
1147         }
1148
1149         /**
1150          * If there are revisions between the ones being compared, return a note saying so.
1151          *
1152          * @return string
1153          */
1154         public function getMultiNotice() {
1155                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1156                         return '';
1157                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1158                         // Comparing two different pages? Count would be meaningless.
1159                         return '';
1160                 }
1161
1162                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1163                         $oldRev = $this->mNewRev; // flip
1164                         $newRev = $this->mOldRev; // flip
1165                 } else { // normal case
1166                         $oldRev = $this->mOldRev;
1167                         $newRev = $this->mNewRev;
1168                 }
1169
1170                 // Sanity: don't show the notice if too many rows must be scanned
1171                 // @todo show some special message for that case
1172                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1173                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1174                         $limit = 100; // use diff-multi-manyusers if too many users
1175                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1176                         $numUsers = count( $users );
1177
1178                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1179                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1180                         }
1181
1182                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1183                 }
1184
1185                 return ''; // nothing
1186         }
1187
1188         /**
1189          * Get a notice about how many intermediate edits and users there are
1190          *
1191          * @param int $numEdits
1192          * @param int $numUsers
1193          * @param int $limit
1194          *
1195          * @return string
1196          */
1197         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1198                 if ( $numUsers === 0 ) {
1199                         $msg = 'diff-multi-sameuser';
1200                 } elseif ( $numUsers > $limit ) {
1201                         $msg = 'diff-multi-manyusers';
1202                         $numUsers = $limit;
1203                 } else {
1204                         $msg = 'diff-multi-otherusers';
1205                 }
1206
1207                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1208         }
1209
1210         /**
1211          * Get a header for a specified revision.
1212          *
1213          * @param Revision $rev
1214          * @param string $complete 'complete' to get the header wrapped depending
1215          *        the visibility of the revision and a link to edit the page.
1216          *
1217          * @return string HTML fragment
1218          */
1219         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1220                 $lang = $this->getLanguage();
1221                 $user = $this->getUser();
1222                 $revtimestamp = $rev->getTimestamp();
1223                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1224                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1225                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1226
1227                 $header = $this->msg(
1228                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1229                         $timestamp,
1230                         $dateofrev,
1231                         $timeofrev
1232                 )->escaped();
1233
1234                 if ( $complete !== 'complete' ) {
1235                         return $header;
1236                 }
1237
1238                 $title = $rev->getTitle();
1239
1240                 $header = Linker::linkKnown( $title, $header, [],
1241                         [ 'oldid' => $rev->getId() ] );
1242
1243                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1244                         $editQuery = [ 'action' => 'edit' ];
1245                         if ( !$rev->isCurrent() ) {
1246                                 $editQuery['oldid'] = $rev->getId();
1247                         }
1248
1249                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1250                         $msg = $this->msg( $key )->escaped();
1251                         $editLink = $this->msg( 'parentheses' )->rawParams(
1252                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1253                         $header .= ' ' . Html::rawElement(
1254                                 'span',
1255                                 [ 'class' => 'mw-diff-edit' ],
1256                                 $editLink
1257                         );
1258                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1259                                 $header = Html::rawElement(
1260                                         'span',
1261                                         [ 'class' => 'history-deleted' ],
1262                                         $header
1263                                 );
1264                         }
1265                 } else {
1266                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1267                 }
1268
1269                 return $header;
1270         }
1271
1272         /**
1273          * Add the header to a diff body
1274          *
1275          * @param string $diff Diff body
1276          * @param string $otitle Old revision header
1277          * @param string $ntitle New revision header
1278          * @param string $multi Notice telling user that there are intermediate
1279          *   revisions between the ones being compared
1280          * @param string $notice Other notices, e.g. that user is viewing deleted content
1281          *
1282          * @return string
1283          */
1284         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1285                 // shared.css sets diff in interface language/dir, but the actual content
1286                 // is often in a different language, mostly the page content language/dir
1287                 $header = Html::openElement( 'table', [
1288                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1289                         'data-mw' => 'interface',
1290                 ] );
1291                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1292
1293                 if ( !$diff && !$otitle ) {
1294                         $header .= "
1295                         <tr class=\"diff-title\" lang=\"{$userLang}\">
1296                         <td class=\"diff-ntitle\">{$ntitle}</td>
1297                         </tr>";
1298                         $multiColspan = 1;
1299                 } else {
1300                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1301                                 $header .= "
1302                                 <col class=\"diff-marker\" />
1303                                 <col class=\"diff-content\" />
1304                                 <col class=\"diff-marker\" />
1305                                 <col class=\"diff-content\" />";
1306                                 $colspan = 2;
1307                                 $multiColspan = 4;
1308                         } else {
1309                                 $colspan = 1;
1310                                 $multiColspan = 2;
1311                         }
1312                         if ( $otitle || $ntitle ) {
1313                                 $header .= "
1314                                 <tr class=\"diff-title\" lang=\"{$userLang}\">
1315                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1316                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1317                                 </tr>";
1318                         }
1319                 }
1320
1321                 if ( $multi != '' ) {
1322                         $header .= "<tr><td colspan=\"{$multiColspan}\" " .
1323                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1324                 }
1325                 if ( $notice != '' ) {
1326                         $header .= "<tr><td colspan=\"{$multiColspan}\" " .
1327                                 "class=\"diff-notice\" lang=\"{$userLang}\">{$notice}</td></tr>";
1328                 }
1329
1330                 return $header . $diff . "</table>";
1331         }
1332
1333         /**
1334          * Use specified text instead of loading from the database
1335          * @param Content $oldContent
1336          * @param Content $newContent
1337          * @since 1.21
1338          */
1339         public function setContent( Content $oldContent, Content $newContent ) {
1340                 $this->mOldContent = $oldContent;
1341                 $this->mNewContent = $newContent;
1342
1343                 $this->mTextLoaded = 2;
1344                 $this->mRevisionsLoaded = true;
1345         }
1346
1347         /**
1348          * Set the language in which the diff text is written
1349          * (Defaults to page content language).
1350          * @param Language|string $lang
1351          * @since 1.19
1352          */
1353         public function setTextLanguage( $lang ) {
1354                 $this->mDiffLang = wfGetLangObj( $lang );
1355         }
1356
1357         /**
1358          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1359          * to a pair of actual integers representing revision ids.
1360          *
1361          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1362          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1363          *
1364          * @return int[] List of two revision ids, older first, later second.
1365          *     Zero signifies invalid argument passed.
1366          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1367          */
1368         public function mapDiffPrevNext( $old, $new ) {
1369                 if ( $new === 'prev' ) {
1370                         // Show diff between revision $old and the previous one. Get previous one from DB.
1371                         $newid = intval( $old );
1372                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1373                 } elseif ( $new === 'next' ) {
1374                         // Show diff between revision $old and the next one. Get next one from DB.
1375                         $oldid = intval( $old );
1376                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1377                 } else {
1378                         $oldid = intval( $old );
1379                         $newid = intval( $new );
1380                 }
1381
1382                 return [ $oldid, $newid ];
1383         }
1384
1385         /**
1386          * Load revision IDs
1387          */
1388         private function loadRevisionIds() {
1389                 if ( $this->mRevisionsIdsLoaded ) {
1390                         return;
1391                 }
1392
1393                 $this->mRevisionsIdsLoaded = true;
1394
1395                 $old = $this->mOldid;
1396                 $new = $this->mNewid;
1397
1398                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1399                 if ( $new === 'next' && $this->mNewid === false ) {
1400                         # if no result, NewId points to the newest old revision. The only newer
1401                         # revision is cur, which is "0".
1402                         $this->mNewid = 0;
1403                 }
1404
1405                 Hooks::run(
1406                         'NewDifferenceEngine',
1407                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1408                 );
1409         }
1410
1411         /**
1412          * Load revision metadata for the specified articles. If newid is 0, then compare
1413          * the old article in oldid to the current article; if oldid is 0, then
1414          * compare the current article to the immediately previous one (ignoring the
1415          * value of newid).
1416          *
1417          * If oldid is false, leave the corresponding revision object set
1418          * to false. This is impossible via ordinary user input, and is provided for
1419          * API convenience.
1420          *
1421          * @return bool
1422          */
1423         public function loadRevisionData() {
1424                 if ( $this->mRevisionsLoaded ) {
1425                         return true;
1426                 }
1427
1428                 // Whether it succeeds or fails, we don't want to try again
1429                 $this->mRevisionsLoaded = true;
1430
1431                 $this->loadRevisionIds();
1432
1433                 // Load the new revision object
1434                 if ( $this->mNewid ) {
1435                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1436                 } else {
1437                         $this->mNewRev = Revision::newFromTitle(
1438                                 $this->getTitle(),
1439                                 false,
1440                                 Revision::READ_NORMAL
1441                         );
1442                 }
1443
1444                 if ( !$this->mNewRev instanceof Revision ) {
1445                         return false;
1446                 }
1447
1448                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1449                 $this->mNewid = $this->mNewRev->getId();
1450                 $this->mNewPage = $this->mNewRev->getTitle();
1451
1452                 // Load the old revision object
1453                 $this->mOldRev = false;
1454                 if ( $this->mOldid ) {
1455                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1456                 } elseif ( $this->mOldid === 0 ) {
1457                         $rev = $this->mNewRev->getPrevious();
1458                         if ( $rev ) {
1459                                 $this->mOldid = $rev->getId();
1460                                 $this->mOldRev = $rev;
1461                         } else {
1462                                 // No previous revision; mark to show as first-version only.
1463                                 $this->mOldid = false;
1464                                 $this->mOldRev = false;
1465                         }
1466                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1467
1468                 if ( is_null( $this->mOldRev ) ) {
1469                         return false;
1470                 }
1471
1472                 if ( $this->mOldRev ) {
1473                         $this->mOldPage = $this->mOldRev->getTitle();
1474                 }
1475
1476                 // Load tags information for both revisions
1477                 $dbr = wfGetDB( DB_REPLICA );
1478                 if ( $this->mOldid !== false ) {
1479                         $this->mOldTags = $dbr->selectField(
1480                                 'tag_summary',
1481                                 'ts_tags',
1482                                 [ 'ts_rev_id' => $this->mOldid ],
1483                                 __METHOD__
1484                         );
1485                 } else {
1486                         $this->mOldTags = false;
1487                 }
1488                 $this->mNewTags = $dbr->selectField(
1489                         'tag_summary',
1490                         'ts_tags',
1491                         [ 'ts_rev_id' => $this->mNewid ],
1492                         __METHOD__
1493                 );
1494
1495                 return true;
1496         }
1497
1498         /**
1499          * Load the text of the revisions, as well as revision data.
1500          *
1501          * @return bool
1502          */
1503         public function loadText() {
1504                 if ( $this->mTextLoaded == 2 ) {
1505                         return true;
1506                 }
1507
1508                 // Whether it succeeds or fails, we don't want to try again
1509                 $this->mTextLoaded = 2;
1510
1511                 if ( !$this->loadRevisionData() ) {
1512                         return false;
1513                 }
1514
1515                 if ( $this->mOldRev ) {
1516                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1517                         if ( $this->mOldContent === null ) {
1518                                 return false;
1519                         }
1520                 }
1521
1522                 if ( $this->mNewRev ) {
1523                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1524                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1525                         if ( $this->mNewContent === null ) {
1526                                 return false;
1527                         }
1528                 }
1529
1530                 return true;
1531         }
1532
1533         /**
1534          * Load the text of the new revision, not the old one
1535          *
1536          * @return bool
1537          */
1538         public function loadNewText() {
1539                 if ( $this->mTextLoaded >= 1 ) {
1540                         return true;
1541                 }
1542
1543                 $this->mTextLoaded = 1;
1544
1545                 if ( !$this->loadRevisionData() ) {
1546                         return false;
1547                 }
1548
1549                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1550
1551                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1552
1553                 return true;
1554         }
1555
1556 }