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                                                         'enableSectionEditLinks' => $this->mNewRev->isCurrent()
 639                                                                 && $this->mNewRev->getTitle()->quickUserCan( 'edit', $this->getUser() ),
 640                                                 ] );
 641                                         }
 642                                 }
 643                         }
 644                 }
 645
 646                 // Allow extensions to optionally not show the final patrolled link
 647                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 648                         # Add redundant patrol link on bottom...
 649                         $out->addHTML( $this->markPatrolledLink() );
 650                 }
 651         }
 652
 653         /**
 654          * @param WikiPage $page
 655          * @param Revision $rev
 656          *
 657          * @return ParserOutput|bool False if the revision was not found
 658          */
 659         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 660                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 661                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 662
 663                 return $parserOutput;
 664         }
 665
 666         /**
 667          * Get the diff text, send it to the OutputPage object
 668          * Returns false if the diff could not be generated, otherwise returns true
 669          *
 670          * @param string|bool $otitle Header for old text or false
 671          * @param string|bool $ntitle Header for new text or false
 672          * @param string $notice HTML between diff header and body
 673          *
 674          * @return bool
 675          */
 676         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 677                 // Allow extensions to affect the output here
 678                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 679
 680                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 681                 if ( $diff === false ) {
 682                         $this->showMissingRevision();
 683
 684                         return false;
 685                 } else {
 686                         $this->showDiffStyle();
 687                         $this->getOutput()->addHTML( $diff );
 688
 689                         return true;
 690                 }
 691         }
 692
 693         /**
 694          * Add style sheets for diff display.
 695          */
 696         public function showDiffStyle() {
 697                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 698         }
 699
 700         /**
 701          * Get complete diff table, including header
 702          *
 703          * @param string|bool $otitle Header for old text or false
 704          * @param string|bool $ntitle Header for new text or false
 705          * @param string $notice HTML between diff header and body
 706          *
 707          * @return mixed
 708          */
 709         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 710                 $body = $this->getDiffBody();
 711                 if ( $body === false ) {
 712                         return false;
 713                 }
 714
 715                 $multi = $this->getMultiNotice();
 716                 // Display a message when the diff is empty
 717                 if ( $body === '' ) {
 718                         $notice .= '<div class="mw-diff-empty">' .
 719                                 $this->msg( 'diff-empty' )->parse() .
 720                                 "</div>\n";
 721                 }
 722
 723                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 724         }
 725
 726         /**
 727          * Get the diff table body, without header
 728          *
 729          * @return mixed (string/false)
 730          */
 731         public function getDiffBody() {
 732                 $this->mCacheHit = true;
 733                 // Check if the diff should be hidden from this user
 734                 if ( !$this->loadRevisionData() ) {
 735                         return false;
 736                 } elseif ( $this->mOldRev &&
 737                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 738                 ) {
 739                         return false;
 740                 } elseif ( $this->mNewRev &&
 741                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 742                 ) {
 743                         return false;
 744                 }
 745                 // Short-circuit
 746                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 747                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 748                 ) {
 749                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 750                                 return '';
 751                         }
 752                 }
 753                 // Cacheable?
 754                 $key = false;
 755                 $cache = ObjectCache::getMainWANInstance();
 756                 if ( $this->mOldid && $this->mNewid ) {
 757                         // Check if subclass is still using the old way
 758                         // for backwards-compatibility
 759                         $key = $this->getDiffBodyCacheKey();
 760                         if ( $key === null ) {
 761                                 $key = call_user_func_array(
 762                                         [ $cache, 'makeKey' ],
 763                                         $this->getDiffBodyCacheKeyParams()
 764                                 );
 765                         }
 766
 767                         // Try cache
 768                         if ( !$this->mRefreshCache ) {
 769                                 $difftext = $cache->get( $key );
 770                                 if ( $difftext ) {
 771                                         wfIncrStats( 'diff_cache.hit' );
 772                                         $difftext = $this->localiseDiff( $difftext );
 773                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 774
 775                                         return $difftext;
 776                                 }
 777                         } // don't try to load but save the result
 778                 }
 779                 $this->mCacheHit = false;
 780
 781                 // Loadtext is permission safe, this just clears out the diff
 782                 if ( !$this->loadText() ) {
 783                         return false;
 784                 }
 785
 786                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 787
 788                 // Avoid PHP 7.1 warning from passing $this by reference
 789                 $diffEngine = $this;
 790
 791                 // Save to cache for 7 days
 792                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 793                         wfIncrStats( 'diff_cache.uncacheable' );
 794                 } elseif ( $key !== false && $difftext !== false ) {
 795                         wfIncrStats( 'diff_cache.miss' );
 796                         $cache->set( $key, $difftext, 7 * 86400 );
 797                 } else {
 798                         wfIncrStats( 'diff_cache.uncacheable' );
 799                 }
 800                 // localise line numbers and title attribute text
 801                 if ( $difftext !== false ) {
 802                         $difftext = $this->localiseDiff( $difftext );
 803                 }
 804
 805                 return $difftext;
 806         }
 807
 808         /**
 809          * Returns the cache key for diff body text or content.
 810          *
 811          * @deprecated since 1.31, use getDiffBodyCacheKeyParams() instead
 812          * @since 1.23
 813          *
 814          * @throws MWException
 815          * @return string|null
 816          */
 817         protected function getDiffBodyCacheKey() {
 818                 return null;
 819         }
 820
 821         /**
 822          * Get the cache key parameters
 823          *
 824          * Subclasses can replace the first element in the array to something
 825          * more specific to the type of diff (e.g. "inline-diff"), or append
 826          * if the cache should vary on more things. Overriding entirely should
 827          * be avoided.
 828          *
 829          * @since 1.31
 830          *
 831          * @return array
 832          * @throws MWException
 833          */
 834         protected function getDiffBodyCacheKeyParams() {
 835                 if ( !$this->mOldid || !$this->mNewid ) {
 836                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 837                 }
 838
 839                 $engine = $this->getEngine();
 840                 $params = [
 841                         'diff',
 842                         $engine,
 843                         self::DIFF_VERSION,
 844                         "old-{$this->mOldid}",
 845                         "rev-{$this->mNewid}"
 846                 ];
 847
 848                 if ( $engine === 'wikidiff2' ) {
 849                         $params[] = phpversion( 'wikidiff2' );
 850                         $params[] = $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' );
 851                 }
 852
 853                 return $params;
 854         }
 855
 856         /**
 857          * Generate a diff, no caching.
 858          *
 859          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 860          * serialization of the given Content objects. This will fail if $old or $new are not
 861          * instances of TextContent.
 862          *
 863          * Subclasses may override this to provide a different rendering for the diff,
 864          * perhaps taking advantage of the content's native form. This is required for all content
 865          * models that are not text based.
 866          *
 867          * @since 1.21
 868          *
 869          * @param Content $old Old content
 870          * @param Content $new New content
 871          *
 872          * @throws MWException If old or new content is not an instance of TextContent.
 873          * @return bool|string
 874          */
 875         public function generateContentDiffBody( Content $old, Content $new ) {
 876                 if ( !( $old instanceof TextContent ) ) {
 877                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 878                                 "override generateContentDiffBody to fix this." );
 879                 }
 880
 881                 if ( !( $new instanceof TextContent ) ) {
 882                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 883                                 . "override generateContentDiffBody to fix this." );
 884                 }
 885
 886                 $otext = $old->serialize();
 887                 $ntext = $new->serialize();
 888
 889                 return $this->generateTextDiffBody( $otext, $ntext );
 890         }
 891
 892         /**
 893          * Generate a diff, no caching
 894          *
 895          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 896          *
 897          * @param string $otext Old text, must be already segmented
 898          * @param string $ntext New text, must be already segmented
 899          *
 900          * @return bool|string
 901          */
 902         public function generateTextDiffBody( $otext, $ntext ) {
 903                 $diff = function () use ( $otext, $ntext ) {
 904                         $time = microtime( true );
 905
 906                         $result = $this->textDiff( $otext, $ntext );
 907
 908                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 909                         MediaWikiServices::getInstance()->getStatsdDataFactory()->timing( 'diff_time', $time );
 910                         // Log requests slower than 99th percentile
 911                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 912                                 wfDebugLog( 'diff',
 913                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 914                         }
 915
 916                         return $result;
 917                 };
 918
 919                 /**
 920                  * @param Status $status
 921                  * @throws FatalError
 922                  */
 923                 $error = function ( $status ) {
 924                         throw new FatalError( $status->getWikiText() );
 925                 };
 926
 927                 // Use PoolCounter if the diff looks like it can be expensive
 928                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 929                         $work = new PoolCounterWorkViaCallback( 'diff',
 930                                 md5( $otext ) . md5( $ntext ),
 931                                 [ 'doWork' => $diff, 'error' => $error ]
 932                         );
 933                         return $work->execute();
 934                 }
 935
 936                 return $diff();
 937         }
 938
 939         /**
 940          * Process $wgExternalDiffEngine and get a sane, usable engine
 941          *
 942          * @return bool|string 'wikidiff2', path to an executable, or false
 943          */
 944         private function getEngine() {
 945                 global $wgExternalDiffEngine;
 946                 // We use the global here instead of Config because we write to the value,
 947                 // and Config is not mutable.
 948                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 949                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 950                         $wgExternalDiffEngine = false;
 951                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 952                         // Same as above, but with no deprecation warnings
 953                         $wgExternalDiffEngine = false;
 954                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 955                         // And prevent people from shooting themselves in the foot...
 956                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 957                         $wgExternalDiffEngine = false;
 958                 }
 959
 960                 if ( is_string( $wgExternalDiffEngine ) && is_executable( $wgExternalDiffEngine ) ) {
 961                         return $wgExternalDiffEngine;
 962                 } elseif ( $wgExternalDiffEngine === false && function_exists( 'wikidiff2_do_diff' ) ) {
 963                         return 'wikidiff2';
 964                 } else {
 965                         // Native PHP
 966                         return false;
 967                 }
 968         }
 969
 970         /**
 971          * Generates diff, to be wrapped internally in a logging/instrumentation
 972          *
 973          * @param string $otext Old text, must be already segmented
 974          * @param string $ntext New text, must be already segmented
 975          * @return bool|string
 976          */
 977         protected function textDiff( $otext, $ntext ) {
 978                 global $wgContLang;
 979
 980                 $otext = str_replace( "\r\n", "\n", $otext );
 981                 $ntext = str_replace( "\r\n", "\n", $ntext );
 982
 983                 $engine = $this->getEngine();
 984
 985                 // Better external diff engine, the 2 may some day be dropped
 986                 // This one does the escaping and segmenting itself
 987                 if ( $engine === 'wikidiff2' ) {
 988                         $wikidiff2Version = phpversion( 'wikidiff2' );
 989                         if (
 990                                 $wikidiff2Version !== false &&
 991                                 version_compare( $wikidiff2Version, '1.5.0', '>=' )
 992                         ) {
 993                                 $text = wikidiff2_do_diff(
 994                                         $otext,
 995                                         $ntext,
 996                                         2,
 997                                         $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' )
 998                                 );
 999                         } else {
1000                                 // Don't pass the 4th parameter for compatibility with older versions of wikidiff2
1001                                 $text = wikidiff2_do_diff(
1002                                         $otext,
1003                                         $ntext,
1004                                         2
1005                                 );
1006
1007                                 // Log a warning in case the configuration value is set to not silently ignore it
1008                                 if ( $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' ) > 0 ) {
1009                                         wfLogWarning( '$wgWikiDiff2MovedParagraphDetectionCutoff is set but has no
1010                                                 effect since the used version of WikiDiff2 does not support it.' );
1011                                 }
1012                         }
1013
1014                         $text .= $this->debug( 'wikidiff2' );
1015
1016                         return $text;
1017                 } elseif ( $engine !== false ) {
1018                         # Diff via the shell
1019                         $tmpDir = wfTempDir();
1020                         $tempName1 = tempnam( $tmpDir, 'diff_' );
1021                         $tempName2 = tempnam( $tmpDir, 'diff_' );
1022
1023                         $tempFile1 = fopen( $tempName1, "w" );
1024                         if ( !$tempFile1 ) {
1025                                 return false;
1026                         }
1027                         $tempFile2 = fopen( $tempName2, "w" );
1028                         if ( !$tempFile2 ) {
1029                                 return false;
1030                         }
1031                         fwrite( $tempFile1, $otext );
1032                         fwrite( $tempFile2, $ntext );
1033                         fclose( $tempFile1 );
1034                         fclose( $tempFile2 );
1035                         $cmd = [ $engine, $tempName1, $tempName2 ];
1036                         $result = Shell::command( $cmd )
1037                                 ->execute();
1038                         $exitCode = $result->getExitCode();
1039                         if ( $exitCode !== 0 ) {
1040                                 throw new Exception( "External diff command returned code {$exitCode}. Stderr: "
1041                                         . wfEscapeWikiText( $result->getStderr() )
1042                                 );
1043                         }
1044                         $difftext = $result->getStdout();
1045                         $difftext .= $this->debug( "external $engine" );
1046                         unlink( $tempName1 );
1047                         unlink( $tempName2 );
1048
1049                         return $difftext;
1050                 }
1051
1052                 # Native PHP diff
1053                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
1054                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
1055                 $diffs = new Diff( $ota, $nta );
1056                 $formatter = new TableDiffFormatter();
1057                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
1058                 $difftext .= $this->debug( 'native PHP' );
1059
1060                 return $difftext;
1061         }
1062
1063         /**
1064          * Generate a debug comment indicating diff generating time,
1065          * server node, and generator backend.
1066          *
1067          * @param string $generator : What diff engine was used
1068          *
1069          * @return string
1070          */
1071         protected function debug( $generator = "internal" ) {
1072                 global $wgShowHostnames;
1073                 if ( !$this->enableDebugComment ) {
1074                         return '';
1075                 }
1076                 $data = [ $generator ];
1077                 if ( $wgShowHostnames ) {
1078                         $data[] = wfHostname();
1079                 }
1080                 $data[] = wfTimestamp( TS_DB );
1081
1082                 return "<!-- diff generator: " .
1083                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1084                         " -->\n";
1085         }
1086
1087         /**
1088          * Localise diff output
1089          *
1090          * @param string $text
1091          * @return string
1092          */
1093         private function localiseDiff( $text ) {
1094                 $text = $this->localiseLineNumbers( $text );
1095                 if ( $this->getEngine() === 'wikidiff2' &&
1096                         version_compare( phpversion( 'wikidiff2' ), '1.5.1', '>=' )
1097                 ) {
1098                         $text = $this->addLocalisedTitleTooltips( $text );
1099                 }
1100                 return $text;
1101         }
1102
1103         /**
1104          * Replace line numbers with the text in the user's language
1105          *
1106          * @param string $text
1107          *
1108          * @return mixed
1109          */
1110         public function localiseLineNumbers( $text ) {
1111                 return preg_replace_callback(
1112                         '/<!--LINE (\d+)-->/',
1113                         [ $this, 'localiseLineNumbersCb' ],
1114                         $text
1115                 );
1116         }
1117
1118         public function localiseLineNumbersCb( $matches ) {
1119                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1120                         return '';
1121                 }
1122
1123                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1124         }
1125
1126         /**
1127          * Add title attributes for tooltips on moved paragraph indicators
1128          *
1129          * @param string $text
1130          * @return string
1131          */
1132         private function addLocalisedTitleTooltips( $text ) {
1133                 return preg_replace_callback(
1134                         '/class="mw-diff-movedpara-(left|right)"/',
1135                         [ $this, 'addLocalisedTitleTooltipsCb' ],
1136                         $text
1137                 );
1138         }
1139
1140         /**
1141          * @param array $matches
1142          * @return string
1143          */
1144         private function addLocalisedTitleTooltipsCb( array $matches ) {
1145                 $key = $matches[1] === 'right' ?
1146                         'diff-paragraph-moved-toold' :
1147                         'diff-paragraph-moved-tonew';
1148                 return $matches[0] . ' title="' . $this->msg( $key )->escaped() . '"';
1149         }
1150
1151         /**
1152          * If there are revisions between the ones being compared, return a note saying so.
1153          *
1154          * @return string
1155          */
1156         public function getMultiNotice() {
1157                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1158                         return '';
1159                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1160                         // Comparing two different pages? Count would be meaningless.
1161                         return '';
1162                 }
1163
1164                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1165                         $oldRev = $this->mNewRev; // flip
1166                         $newRev = $this->mOldRev; // flip
1167                 } else { // normal case
1168                         $oldRev = $this->mOldRev;
1169                         $newRev = $this->mNewRev;
1170                 }
1171
1172                 // Sanity: don't show the notice if too many rows must be scanned
1173                 // @todo show some special message for that case
1174                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1175                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1176                         $limit = 100; // use diff-multi-manyusers if too many users
1177                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1178                         $numUsers = count( $users );
1179
1180                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1181                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1182                         }
1183
1184                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1185                 }
1186
1187                 return ''; // nothing
1188         }
1189
1190         /**
1191          * Get a notice about how many intermediate edits and users there are
1192          *
1193          * @param int $numEdits
1194          * @param int $numUsers
1195          * @param int $limit
1196          *
1197          * @return string
1198          */
1199         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1200                 if ( $numUsers === 0 ) {
1201                         $msg = 'diff-multi-sameuser';
1202                 } elseif ( $numUsers > $limit ) {
1203                         $msg = 'diff-multi-manyusers';
1204                         $numUsers = $limit;
1205                 } else {
1206                         $msg = 'diff-multi-otherusers';
1207                 }
1208
1209                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1210         }
1211
1212         /**
1213          * Get a header for a specified revision.
1214          *
1215          * @param Revision $rev
1216          * @param string $complete 'complete' to get the header wrapped depending
1217          *        the visibility of the revision and a link to edit the page.
1218          *
1219          * @return string HTML fragment
1220          */
1221         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1222                 $lang = $this->getLanguage();
1223                 $user = $this->getUser();
1224                 $revtimestamp = $rev->getTimestamp();
1225                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1226                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1227                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1228
1229                 $header = $this->msg(
1230                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1231                         $timestamp,
1232                         $dateofrev,
1233                         $timeofrev
1234                 )->escaped();
1235
1236                 if ( $complete !== 'complete' ) {
1237                         return $header;
1238                 }
1239
1240                 $title = $rev->getTitle();
1241
1242                 $header = Linker::linkKnown( $title, $header, [],
1243                         [ 'oldid' => $rev->getId() ] );
1244
1245                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1246                         $editQuery = [ 'action' => 'edit' ];
1247                         if ( !$rev->isCurrent() ) {
1248                                 $editQuery['oldid'] = $rev->getId();
1249                         }
1250
1251                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1252                         $msg = $this->msg( $key )->escaped();
1253                         $editLink = $this->msg( 'parentheses' )->rawParams(
1254                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1255                         $header .= ' ' . Html::rawElement(
1256                                 'span',
1257                                 [ 'class' => 'mw-diff-edit' ],
1258                                 $editLink
1259                         );
1260                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1261                                 $header = Html::rawElement(
1262                                         'span',
1263                                         [ 'class' => 'history-deleted' ],
1264                                         $header
1265                                 );
1266                         }
1267                 } else {
1268                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1269                 }
1270
1271                 return $header;
1272         }
1273
1274         /**
1275          * Add the header to a diff body
1276          *
1277          * @param string $diff Diff body
1278          * @param string $otitle Old revision header
1279          * @param string $ntitle New revision header
1280          * @param string $multi Notice telling user that there are intermediate
1281          *   revisions between the ones being compared
1282          * @param string $notice Other notices, e.g. that user is viewing deleted content
1283          *
1284          * @return string
1285          */
1286         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1287                 // shared.css sets diff in interface language/dir, but the actual content
1288                 // is often in a different language, mostly the page content language/dir
1289                 $header = Html::openElement( 'table', [
1290                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1291                         'data-mw' => 'interface',
1292                 ] );
1293                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1294
1295                 if ( !$diff && !$otitle ) {
1296                         $header .= "
1297                         <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1298                         <td class=\"diff-ntitle\">{$ntitle}</td>
1299                         </tr>";
1300                         $multiColspan = 1;
1301                 } else {
1302                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1303                                 $header .= "
1304                                 <col class=\"diff-marker\" />
1305                                 <col class=\"diff-content\" />
1306                                 <col class=\"diff-marker\" />
1307                                 <col class=\"diff-content\" />";
1308                                 $colspan = 2;
1309                                 $multiColspan = 4;
1310                         } else {
1311                                 $colspan = 1;
1312                                 $multiColspan = 2;
1313                         }
1314                         if ( $otitle || $ntitle ) {
1315                                 $header .= "
1316                                 <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1317                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1318                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1319                                 </tr>";
1320                         }
1321                 }
1322
1323                 if ( $multi != '' ) {
1324                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1325                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1326                 }
1327                 if ( $notice != '' ) {
1328                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1329                                 "lang=\"{$userLang}\">{$notice}</td></tr>";
1330                 }
1331
1332                 return $header . $diff . "</table>";
1333         }
1334
1335         /**
1336          * Use specified text instead of loading from the database
1337          * @param Content $oldContent
1338          * @param Content $newContent
1339          * @since 1.21
1340          */
1341         public function setContent( Content $oldContent, Content $newContent ) {
1342                 $this->mOldContent = $oldContent;
1343                 $this->mNewContent = $newContent;
1344
1345                 $this->mTextLoaded = 2;
1346                 $this->mRevisionsLoaded = true;
1347         }
1348
1349         /**
1350          * Set the language in which the diff text is written
1351          * (Defaults to page content language).
1352          * @param Language|string $lang
1353          * @since 1.19
1354          */
1355         public function setTextLanguage( $lang ) {
1356                 $this->mDiffLang = wfGetLangObj( $lang );
1357         }
1358
1359         /**
1360          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1361          * to a pair of actual integers representing revision ids.
1362          *
1363          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1364          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1365          *
1366          * @return int[] List of two revision ids, older first, later second.
1367          *     Zero signifies invalid argument passed.
1368          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1369          */
1370         public function mapDiffPrevNext( $old, $new ) {
1371                 if ( $new === 'prev' ) {
1372                         // Show diff between revision $old and the previous one. Get previous one from DB.
1373                         $newid = intval( $old );
1374                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1375                 } elseif ( $new === 'next' ) {
1376                         // Show diff between revision $old and the next one. Get next one from DB.
1377                         $oldid = intval( $old );
1378                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1379                 } else {
1380                         $oldid = intval( $old );
1381                         $newid = intval( $new );
1382                 }
1383
1384                 return [ $oldid, $newid ];
1385         }
1386
1387         /**
1388          * Load revision IDs
1389          */
1390         private function loadRevisionIds() {
1391                 if ( $this->mRevisionsIdsLoaded ) {
1392                         return;
1393                 }
1394
1395                 $this->mRevisionsIdsLoaded = true;
1396
1397                 $old = $this->mOldid;
1398                 $new = $this->mNewid;
1399
1400                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1401                 if ( $new === 'next' && $this->mNewid === false ) {
1402                         # if no result, NewId points to the newest old revision. The only newer
1403                         # revision is cur, which is "0".
1404                         $this->mNewid = 0;
1405                 }
1406
1407                 Hooks::run(
1408                         'NewDifferenceEngine',
1409                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1410                 );
1411         }
1412
1413         /**
1414          * Load revision metadata for the specified articles. If newid is 0, then compare
1415          * the old article in oldid to the current article; if oldid is 0, then
1416          * compare the current article to the immediately previous one (ignoring the
1417          * value of newid).
1418          *
1419          * If oldid is false, leave the corresponding revision object set
1420          * to false. This is impossible via ordinary user input, and is provided for
1421          * API convenience.
1422          *
1423          * @return bool
1424          */
1425         public function loadRevisionData() {
1426                 if ( $this->mRevisionsLoaded ) {
1427                         return true;
1428                 }
1429
1430                 // Whether it succeeds or fails, we don't want to try again
1431                 $this->mRevisionsLoaded = true;
1432
1433                 $this->loadRevisionIds();
1434
1435                 // Load the new revision object
1436                 if ( $this->mNewid ) {
1437                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1438                 } else {
1439                         $this->mNewRev = Revision::newFromTitle(
1440                                 $this->getTitle(),
1441                                 false,
1442                                 Revision::READ_NORMAL
1443                         );
1444                 }
1445
1446                 if ( !$this->mNewRev instanceof Revision ) {
1447                         return false;
1448                 }
1449
1450                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1451                 $this->mNewid = $this->mNewRev->getId();
1452                 $this->mNewPage = $this->mNewRev->getTitle();
1453
1454                 // Load the old revision object
1455                 $this->mOldRev = false;
1456                 if ( $this->mOldid ) {
1457                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1458                 } elseif ( $this->mOldid === 0 ) {
1459                         $rev = $this->mNewRev->getPrevious();
1460                         if ( $rev ) {
1461                                 $this->mOldid = $rev->getId();
1462                                 $this->mOldRev = $rev;
1463                         } else {
1464                                 // No previous revision; mark to show as first-version only.
1465                                 $this->mOldid = false;
1466                                 $this->mOldRev = false;
1467                         }
1468                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1469
1470                 if ( is_null( $this->mOldRev ) ) {
1471                         return false;
1472                 }
1473
1474                 if ( $this->mOldRev ) {
1475                         $this->mOldPage = $this->mOldRev->getTitle();
1476                 }
1477
1478                 // Load tags information for both revisions
1479                 $dbr = wfGetDB( DB_REPLICA );
1480                 if ( $this->mOldid !== false ) {
1481                         $this->mOldTags = $dbr->selectField(
1482                                 'tag_summary',
1483                                 'ts_tags',
1484                                 [ 'ts_rev_id' => $this->mOldid ],
1485                                 __METHOD__
1486                         );
1487                 } else {
1488                         $this->mOldTags = false;
1489                 }
1490                 $this->mNewTags = $dbr->selectField(
1491                         'tag_summary',
1492                         'ts_tags',
1493                         [ 'ts_rev_id' => $this->mNewid ],
1494                         __METHOD__
1495                 );
1496
1497                 return true;
1498         }
1499
1500         /**
1501          * Load the text of the revisions, as well as revision data.
1502          *
1503          * @return bool
1504          */
1505         public function loadText() {
1506                 if ( $this->mTextLoaded == 2 ) {
1507                         return true;
1508                 }
1509
1510                 // Whether it succeeds or fails, we don't want to try again
1511                 $this->mTextLoaded = 2;
1512
1513                 if ( !$this->loadRevisionData() ) {
1514                         return false;
1515                 }
1516
1517                 if ( $this->mOldRev ) {
1518                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1519                         if ( $this->mOldContent === null ) {
1520                                 return false;
1521                         }
1522                 }
1523
1524                 if ( $this->mNewRev ) {
1525                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1526                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1527                         if ( $this->mNewContent === null ) {
1528                                 return false;
1529                         }
1530                 }
1531
1532                 return true;
1533         }
1534
1535         /**
1536          * Load the text of the new revision, not the old one
1537          *
1538          * @return bool
1539          */
1540         public function loadNewText() {
1541                 if ( $this->mTextLoaded >= 1 ) {
1542                         return true;
1543                 }
1544
1545                 $this->mTextLoaded = 1;
1546
1547                 if ( !$this->loadRevisionData() ) {
1548                         return false;
1549                 }
1550
1551                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1552
1553                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1554
1555                 return true;
1556         }
1557
1558 }