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 Revision ID or 0 for current */
  40         public $mOldid;
  41
  42         /** @var int|string Revision ID or null for current or an alias such as 'next' */
  43         public $mNewid;
  44
  45         private $mOldTags;
  46         private $mNewTags;
  47
  48         /** @var Content|null */
  49         public $mOldContent;
  50
  51         /** @var Content|null */
  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|null */
  64         public $mOldRev;
  65
  66         /** @var Revision|null */
  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         /**
  79          * Was the content overridden via setContent()?
  80          * If the content was overridden, most internal state (e.g. mOldid or mOldRev) should be ignored.
  81          * @var bool
  82          */
  83         protected $isContentOverridden = false;
  84
  85         /** @var bool Was the diff fetched from cache? */
  86         public $mCacheHit = false;
  87
  88         /**
  89          * Set this to true to add debug info to the HTML output.
  90          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  91          * (T22601)
  92          */
  93         public $enableDebugComment = false;
  94
  95         /** @var bool If true, line X is not displayed when X is 1, for example
  96          *    to increase readability and conserve space with many small diffs.
  97          */
  98         protected $mReducedLineNumbers = false;
  99
 100         /** @var string Link to action=markpatrolled */
 101         protected $mMarkPatrolledLink = null;
 102
 103         /** @var bool Show rev_deleted content if allowed */
 104         protected $unhide = false;
 105
 106         /** @var bool Refresh the diff cache */
 107         protected $mRefreshCache = false;
 108
 109         /**#@-*/
 110
 111         /**
 112          * @param IContextSource|null $context Context to use, anything else will be ignored
 113          * @param int $old Old ID we want to show and diff with.
 114          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 115          * @param int $rcid Deprecated, no longer used!
 116          * @param bool $refreshCache If set, refreshes the diff cache
 117          * @param bool $unhide If set, allow viewing deleted revs
 118          */
 119         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 120                 $refreshCache = false, $unhide = false
 121         ) {
 122                 if ( $context instanceof IContextSource ) {
 123                         $this->setContext( $context );
 124                 }
 125
 126                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 127
 128                 $this->mOldid = $old;
 129                 $this->mNewid = $new;
 130                 $this->mRefreshCache = $refreshCache;
 131                 $this->unhide = $unhide;
 132         }
 133
 134         /**
 135          * @param bool $value
 136          */
 137         public function setReducedLineNumbers( $value = true ) {
 138                 $this->mReducedLineNumbers = $value;
 139         }
 140
 141         /**
 142          * Get the language of the difference engine, defaults to page content language
 143          *
 144          * @return Language
 145          */
 146         public function getDiffLang() {
 147                 if ( $this->mDiffLang === null ) {
 148                         # Default language in which the diff text is written.
 149                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 150                 }
 151
 152                 return $this->mDiffLang;
 153         }
 154
 155         /**
 156          * @return bool
 157          */
 158         public function wasCacheHit() {
 159                 return $this->mCacheHit;
 160         }
 161
 162         /**
 163          * @return int
 164          */
 165         public function getOldid() {
 166                 $this->loadRevisionIds();
 167
 168                 return $this->mOldid;
 169         }
 170
 171         /**
 172          * @return bool|int
 173          */
 174         public function getNewid() {
 175                 $this->loadRevisionIds();
 176
 177                 return $this->mNewid;
 178         }
 179
 180         /**
 181          * Look up a special:Undelete link to the given deleted revision id,
 182          * as a workaround for being unable to load deleted diffs in currently.
 183          *
 184          * @param int $id Revision ID
 185          *
 186          * @return string|bool Link HTML or false
 187          */
 188         public function deletedLink( $id ) {
 189                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 190                         $dbr = wfGetDB( DB_REPLICA );
 191                         $arQuery = Revision::getArchiveQueryInfo();
 192                         $row = $dbr->selectRow(
 193                                 $arQuery['tables'],
 194                                 array_merge( $arQuery['fields'], [ 'ar_namespace', 'ar_title' ] ),
 195                                 [ 'ar_rev_id' => $id ],
 196                                 __METHOD__,
 197                                 [],
 198                                 $arQuery['joins']
 199                         );
 200                         if ( $row ) {
 201                                 $rev = Revision::newFromArchiveRow( $row );
 202                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 203
 204                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
 205                                         'target' => $title->getPrefixedText(),
 206                                         'timestamp' => $rev->getTimestamp()
 207                                 ] );
 208                         }
 209                 }
 210
 211                 return false;
 212         }
 213
 214         /**
 215          * Build a wikitext link toward a deleted revision, if viewable.
 216          *
 217          * @param int $id Revision ID
 218          *
 219          * @return string Wikitext fragment
 220          */
 221         public function deletedIdMarker( $id ) {
 222                 $link = $this->deletedLink( $id );
 223                 if ( $link ) {
 224                         return "[$link $id]";
 225                 } else {
 226                         return (string)$id;
 227                 }
 228         }
 229
 230         private function showMissingRevision() {
 231                 $out = $this->getOutput();
 232
 233                 $missing = [];
 234                 if ( $this->mOldRev === null ||
 235                         ( $this->mOldRev && $this->mOldContent === null )
 236                 ) {
 237                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 238                 }
 239                 if ( $this->mNewRev === null ||
 240                         ( $this->mNewRev && $this->mNewContent === null )
 241                 ) {
 242                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 243                 }
 244
 245                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 246                 $msg = $this->msg( 'difference-missing-revision' )
 247                         ->params( $this->getLanguage()->listToText( $missing ) )
 248                         ->numParams( count( $missing ) )
 249                         ->parseAsBlock();
 250                 $out->addHTML( $msg );
 251         }
 252
 253         public function showDiffPage( $diffOnly = false ) {
 254                 # Allow frames except in certain special cases
 255                 $out = $this->getOutput();
 256                 $out->allowClickjacking();
 257                 $out->setRobotPolicy( 'noindex,nofollow' );
 258
 259                 // Allow extensions to add any extra output here
 260                 Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
 261
 262                 if ( !$this->loadRevisionData() ) {
 263                         if ( Hooks::run( 'DifferenceEngineShowDiffPageMaybeShowMissingRevision', [ $this ] ) ) {
 264                                 $this->showMissingRevision();
 265                         }
 266                         return;
 267                 }
 268
 269                 $user = $this->getUser();
 270                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 271                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 272                         $permErrors = wfMergeErrorArrays( $permErrors,
 273                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 274                 }
 275                 if ( count( $permErrors ) ) {
 276                         throw new PermissionsError( 'read', $permErrors );
 277                 }
 278
 279                 $rollback = '';
 280
 281                 $query = [];
 282                 # Carry over 'diffonly' param via navigation links
 283                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 284                         $query['diffonly'] = $diffOnly;
 285                 }
 286                 # Cascade unhide param in links for easy deletion browsing
 287                 if ( $this->unhide ) {
 288                         $query['unhide'] = 1;
 289                 }
 290
 291                 # Check if one of the revisions is deleted/suppressed
 292                 $deleted = $suppressed = false;
 293                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 294
 295                 $revisionTools = [];
 296
 297                 # mOldRev is false if the difference engine is called with a "vague" query for
 298                 # a diff between a version V and its previous version V' AND the version V
 299                 # is the first version of that article. In that case, V' does not exist.
 300                 if ( $this->mOldRev === false ) {
 301                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 302                         $samePage = true;
 303                         $oldHeader = '';
 304                         // Allow extensions to change the $oldHeader variable
 305                         Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
 306                 } else {
 307                         Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 308
 309                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 310                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 311                                 $samePage = true;
 312                         } else {
 313                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 314                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 315                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 316                                 $samePage = false;
 317                         }
 318
 319                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 320                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 321                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 322                                         if ( $rollbackLink ) {
 323                                                 $out->preventClickjacking();
 324                                                 $rollback = "\u{00A0}\u{00A0}\u{00A0}" . $rollbackLink;
 325                                         }
 326                                 }
 327
 328                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 329                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 330                                 ) {
 331                                         $undoLink = Html::element( 'a', [
 332                                                         'href' => $this->mNewPage->getLocalURL( [
 333                                                                 'action' => 'edit',
 334                                                                 'undoafter' => $this->mOldid,
 335                                                                 'undo' => $this->mNewid
 336                                                         ] ),
 337                                                         'title' => Linker::titleAttrib( 'undo' ),
 338                                                 ],
 339                                                 $this->msg( 'editundo' )->text()
 340                                         );
 341                                         $revisionTools['mw-diff-undo'] = $undoLink;
 342                                 }
 343                         }
 344
 345                         # Make "previous revision link"
 346                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 347                                 $prevlink = Linker::linkKnown(
 348                                         $this->mOldPage,
 349                                         $this->msg( 'previousdiff' )->escaped(),
 350                                         [ 'id' => 'differences-prevlink' ],
 351                                         [ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
 352                                 );
 353                         } else {
 354                                 $prevlink = "\u{00A0}";
 355                         }
 356
 357                         if ( $this->mOldRev->isMinor() ) {
 358                                 $oldminor = ChangesList::flag( 'minor' );
 359                         } else {
 360                                 $oldminor = '';
 361                         }
 362
 363                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 364                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 365                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );
 366
 367                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 368                                 '<div id="mw-diff-otitle2">' .
 369                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 370                                 '<div id="mw-diff-otitle3">' . $oldminor .
 371                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 372                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 373                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 374
 375                         // Allow extensions to change the $oldHeader variable
 376                         Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
 377                                 $diffOnly, $ldel, $this->unhide ] );
 378
 379                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 380                                 $deleted = true; // old revisions text is hidden
 381                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 382                                         $suppressed = true; // also suppressed
 383                                 }
 384                         }
 385
 386                         # Check if this user can see the revisions
 387                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 388                                 $allowed = false;
 389                         }
 390                 }
 391
 392                 $out->addJsConfigVars( [
 393                         'wgDiffOldId' => $this->mOldid,
 394                         'wgDiffNewId' => $this->mNewid,
 395                 ] );
 396
 397                 # Make "next revision link"
 398                 # Skip next link on the top revision
 399                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 400                         $nextlink = Linker::linkKnown(
 401                                 $this->mNewPage,
 402                                 $this->msg( 'nextdiff' )->escaped(),
 403                                 [ 'id' => 'differences-nextlink' ],
 404                                 [ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
 405                         );
 406                 } else {
 407                         $nextlink = "\u{00A0}";
 408                 }
 409
 410                 if ( $this->mNewRev->isMinor() ) {
 411                         $newminor = ChangesList::flag( 'minor' );
 412                 } else {
 413                         $newminor = '';
 414                 }
 415
 416                 # Handle RevisionDelete links...
 417                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 418
 419                 # Allow extensions to define their own revision tools
 420                 Hooks::run( 'DiffRevisionTools',
 421                         [ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
 422                 $formattedRevisionTools = [];
 423                 // Put each one in parentheses (poor man's button)
 424                 foreach ( $revisionTools as $key => $tool ) {
 425                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 426                         $element = Html::rawElement(
 427                                 'span',
 428                                 [ 'class' => $toolClass ],
 429                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 430                         );
 431                         $formattedRevisionTools[] = $element;
 432                 }
 433                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 434                         ' ' . implode( ' ', $formattedRevisionTools );
 435                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );
 436
 437                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 438                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 439                         " $rollback</div>" .
 440                         '<div id="mw-diff-ntitle3">' . $newminor .
 441                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 442                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 443                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 444
 445                 // Allow extensions to change the $newHeader variable
 446                 Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
 447                         $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
 448
 449                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 450                         $deleted = true; // new revisions text is hidden
 451                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 452                                 $suppressed = true; // also suppressed
 453                         }
 454                 }
 455
 456                 # If the diff cannot be shown due to a deleted revision, then output
 457                 # the diff header and links to unhide (if available)...
 458                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 459                         $this->showDiffStyle();
 460                         $multi = $this->getMultiNotice();
 461                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 462                         if ( !$allowed ) {
 463                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 464                                 # Give explanation for why revision is not visible
 465                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 466                                         [ $msg ] );
 467                         } else {
 468                                 # Give explanation and add a link to view the diff...
 469                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
 470                                 $link = $this->getTitle()->getFullURL( $query );
 471                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 472                                 $out->wrapWikiMsg(
 473                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 474                                         [ $msg, $link ]
 475                                 );
 476                         }
 477                 # Otherwise, output a regular diff...
 478                 } else {
 479                         # Add deletion notice if the user is viewing deleted content
 480                         $notice = '';
 481                         if ( $deleted ) {
 482                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 483                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 484                                         $this->msg( $msg )->parse() .
 485                                         "</div>\n";
 486                         }
 487                         $this->showDiff( $oldHeader, $newHeader, $notice );
 488                         if ( !$diffOnly ) {
 489                                 $this->renderNewRevision();
 490                         }
 491                 }
 492         }
 493
 494         /**
 495          * Build a link to mark a change as patrolled.
 496          *
 497          * Returns empty string if there's either no revision to patrol or the user is not allowed to.
 498          * Side effect: When the patrol link is build, this method will call
 499          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 500          *
 501          * @return string HTML or empty string
 502          */
 503         public function markPatrolledLink() {
 504                 if ( $this->mMarkPatrolledLink === null ) {
 505                         $linkInfo = $this->getMarkPatrolledLinkInfo();
 506                         // If false, there is no patrol link needed/allowed
 507                         if ( !$linkInfo ) {
 508                                 $this->mMarkPatrolledLink = '';
 509                         } else {
 510                                 $this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
 511                                         Linker::linkKnown(
 512                                                 $this->mNewPage,
 513                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 514                                                 [],
 515                                                 [
 516                                                         'action' => 'markpatrolled',
 517                                                         'rcid' => $linkInfo['rcid'],
 518                                                 ]
 519                                         ) . ']</span>';
 520                                 // Allow extensions to change the markpatrolled link
 521                                 Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
 522                                         &$this->mMarkPatrolledLink, $linkInfo['rcid'] ] );
 523                         }
 524                 }
 525                 return $this->mMarkPatrolledLink;
 526         }
 527
 528         /**
 529          * Returns an array of meta data needed to build a "mark as patrolled" link and
 530          * adds the mediawiki.page.patrol.ajax to the output.
 531          *
 532          * @return array|false An array of meta data for a patrol link (rcid only)
 533          *  or false if no link is needed
 534          */
 535         protected function getMarkPatrolledLinkInfo() {
 536                 global $wgUseRCPatrol;
 537
 538                 $user = $this->getUser();
 539
 540                 // Prepare a change patrol link, if applicable
 541                 if (
 542                         // Is patrolling enabled and the user allowed to?
 543                         $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 544                         // Only do this if the revision isn't more than 6 hours older
 545                         // than the Max RC age (6h because the RC might not be cleaned out regularly)
 546                         RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 547                 ) {
 548                         // Look for an unpatrolled change corresponding to this diff
 549                         $db = wfGetDB( DB_REPLICA );
 550                         $change = RecentChange::newFromConds(
 551                                 [
 552                                         'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 553                                         'rc_this_oldid' => $this->mNewid,
 554                                         'rc_patrolled' => RecentChange::PRC_UNPATROLLED
 555                                 ],
 556                                 __METHOD__
 557                         );
 558
 559                         if ( $change && !$change->getPerformer()->equals( $user ) ) {
 560                                 $rcid = $change->getAttribute( 'rc_id' );
 561                         } else {
 562                                 // None found or the page has been created by the current user.
 563                                 // If the user could patrol this it already would be patrolled
 564                                 $rcid = 0;
 565                         }
 566
 567                         // Allow extensions to possibly change the rcid here
 568                         // For example the rcid might be set to zero due to the user
 569                         // being the same as the performer of the change but an extension
 570                         // might still want to show it under certain conditions
 571                         Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
 572
 573                         // Build the link
 574                         if ( $rcid ) {
 575                                 $this->getOutput()->preventClickjacking();
 576                                 if ( $user->isAllowed( 'writeapi' ) ) {
 577                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 578                                 }
 579
 580                                 return [
 581                                         'rcid' => $rcid,
 582                                 ];
 583                         }
 584                 }
 585
 586                 // No mark as patrolled link applicable
 587                 return false;
 588         }
 589
 590         /**
 591          * @param Revision $rev
 592          *
 593          * @return string
 594          */
 595         protected function revisionDeleteLink( $rev ) {
 596                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 597                 if ( $link !== '' ) {
 598                         $link = "\u{00A0}\u{00A0}\u{00A0}" . $link . ' ';
 599                 }
 600
 601                 return $link;
 602         }
 603
 604         /**
 605          * Show the new revision of the page.
 606          */
 607         public function renderNewRevision() {
 608                 $out = $this->getOutput();
 609                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 610                 # Add "current version as of X" title
 611                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 612                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 613                 # Page content may be handled by a hooked call instead...
 614                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 615                         $this->loadNewText();
 616                         $out->setRevisionId( $this->mNewid );
 617                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 618                         $out->setArticleFlag( true );
 619
 620                         if ( !Hooks::run( 'ArticleContentViewCustom',
 621                                 [ $this->mNewContent, $this->mNewPage, $out ] )
 622                         ) {
 623                                 // Handled by extension
 624                         } else {
 625                                 // Normal page
 626                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 627                                         // If the Title stored in the context is the same as the one
 628                                         // of the new revision, we can use its associated WikiPage
 629                                         // object.
 630                                         $wikiPage = $this->getWikiPage();
 631                                 } else {
 632                                         // Otherwise we need to create our own WikiPage object
 633                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 634                                 }
 635
 636                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 637
 638                                 # WikiPage::getParserOutput() should not return false, but just in case
 639                                 if ( $parserOutput ) {
 640                                         // Allow extensions to change parser output here
 641                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput',
 642                                                 [ $this, $out, $parserOutput, $wikiPage ] )
 643                                         ) {
 644                                                 $out->addParserOutput( $parserOutput, [
 645                                                         'enableSectionEditLinks' => $this->mNewRev->isCurrent()
 646                                                                 && $this->mNewRev->getTitle()->quickUserCan( 'edit', $this->getUser() ),
 647                                                 ] );
 648                                         }
 649                                 }
 650                         }
 651                 }
 652
 653                 // Allow extensions to optionally not show the final patrolled link
 654                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 655                         # Add redundant patrol link on bottom...
 656                         $out->addHTML( $this->markPatrolledLink() );
 657                 }
 658         }
 659
 660         /**
 661          * @param WikiPage $page
 662          * @param Revision $rev
 663          *
 664          * @return ParserOutput|bool False if the revision was not found
 665          */
 666         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 667                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 668                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 669
 670                 return $parserOutput;
 671         }
 672
 673         /**
 674          * Get the diff text, send it to the OutputPage object
 675          * Returns false if the diff could not be generated, otherwise returns true
 676          *
 677          * @param string|bool $otitle Header for old text or false
 678          * @param string|bool $ntitle Header for new text or false
 679          * @param string $notice HTML between diff header and body
 680          *
 681          * @return bool
 682          */
 683         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 684                 // Allow extensions to affect the output here
 685                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 686
 687                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 688                 if ( $diff === false ) {
 689                         $this->showMissingRevision();
 690
 691                         return false;
 692                 } else {
 693                         $this->showDiffStyle();
 694                         $this->getOutput()->addHTML( $diff );
 695
 696                         return true;
 697                 }
 698         }
 699
 700         /**
 701          * Add style sheets for diff display.
 702          */
 703         public function showDiffStyle() {
 704                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 705         }
 706
 707         /**
 708          * Get complete diff table, including header
 709          *
 710          * @param string|bool $otitle Header for old text or false
 711          * @param string|bool $ntitle Header for new text or false
 712          * @param string $notice HTML between diff header and body
 713          *
 714          * @return mixed
 715          */
 716         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 717                 $body = $this->getDiffBody();
 718                 if ( $body === false ) {
 719                         return false;
 720                 }
 721
 722                 $multi = $this->getMultiNotice();
 723                 // Display a message when the diff is empty
 724                 if ( $body === '' ) {
 725                         $notice .= '<div class="mw-diff-empty">' .
 726                                 $this->msg( 'diff-empty' )->parse() .
 727                                 "</div>\n";
 728                 }
 729
 730                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 731         }
 732
 733         /**
 734          * Get the diff table body, without header
 735          *
 736          * @return mixed (string/false)
 737          */
 738         public function getDiffBody() {
 739                 $this->mCacheHit = true;
 740                 // Check if the diff should be hidden from this user
 741                 if ( !$this->loadRevisionData() ) {
 742                         return false;
 743                 } elseif ( $this->mOldRev &&
 744                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 745                 ) {
 746                         return false;
 747                 } elseif ( $this->mNewRev &&
 748                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 749                 ) {
 750                         return false;
 751                 }
 752                 // Short-circuit
 753                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 754                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 755                 ) {
 756                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 757                                 return '';
 758                         }
 759                 }
 760                 // Cacheable?
 761                 $key = false;
 762                 $cache = ObjectCache::getMainWANInstance();
 763                 if ( $this->mOldid && $this->mNewid ) {
 764                         // Check if subclass is still using the old way
 765                         // for backwards-compatibility
 766                         $key = $this->getDiffBodyCacheKey();
 767                         if ( $key === null ) {
 768                                 $key = $cache->makeKey( ...$this->getDiffBodyCacheKeyParams() );
 769                         }
 770
 771                         // Try cache
 772                         if ( !$this->mRefreshCache ) {
 773                                 $difftext = $cache->get( $key );
 774                                 if ( $difftext ) {
 775                                         wfIncrStats( 'diff_cache.hit' );
 776                                         $difftext = $this->localiseDiff( $difftext );
 777                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 778
 779                                         return $difftext;
 780                                 }
 781                         } // don't try to load but save the result
 782                 }
 783                 $this->mCacheHit = false;
 784
 785                 // Loadtext is permission safe, this just clears out the diff
 786                 if ( !$this->loadText() ) {
 787                         return false;
 788                 }
 789
 790                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 791
 792                 // Avoid PHP 7.1 warning from passing $this by reference
 793                 $diffEngine = $this;
 794
 795                 // Save to cache for 7 days
 796                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 797                         wfIncrStats( 'diff_cache.uncacheable' );
 798                 } elseif ( $key !== false && $difftext !== false ) {
 799                         wfIncrStats( 'diff_cache.miss' );
 800                         $cache->set( $key, $difftext, 7 * 86400 );
 801                 } else {
 802                         wfIncrStats( 'diff_cache.uncacheable' );
 803                 }
 804                 // localise line numbers and title attribute text
 805                 if ( $difftext !== false ) {
 806                         $difftext = $this->localiseDiff( $difftext );
 807                 }
 808
 809                 return $difftext;
 810         }
 811
 812         /**
 813          * Returns the cache key for diff body text or content.
 814          *
 815          * @deprecated since 1.31, use getDiffBodyCacheKeyParams() instead
 816          * @since 1.23
 817          *
 818          * @throws MWException
 819          * @return string|null
 820          */
 821         protected function getDiffBodyCacheKey() {
 822                 return null;
 823         }
 824
 825         /**
 826          * Get the cache key parameters
 827          *
 828          * Subclasses can replace the first element in the array to something
 829          * more specific to the type of diff (e.g. "inline-diff"), or append
 830          * if the cache should vary on more things. Overriding entirely should
 831          * be avoided.
 832          *
 833          * @since 1.31
 834          *
 835          * @return array
 836          * @throws MWException
 837          */
 838         protected function getDiffBodyCacheKeyParams() {
 839                 if ( !$this->mOldid || !$this->mNewid ) {
 840                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 841                 }
 842
 843                 $engine = $this->getEngine();
 844                 $params = [
 845                         'diff',
 846                         $engine,
 847                         self::DIFF_VERSION,
 848                         "old-{$this->mOldid}",
 849                         "rev-{$this->mNewid}"
 850                 ];
 851
 852                 if ( $engine === 'wikidiff2' ) {
 853                         $params[] = phpversion( 'wikidiff2' );
 854                         $params[] = $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' );
 855                 }
 856
 857                 return $params;
 858         }
 859
 860         /**
 861          * Generate a diff, no caching.
 862          *
 863          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 864          * serialization of the given Content objects. This will fail if $old or $new are not
 865          * instances of TextContent.
 866          *
 867          * Subclasses may override this to provide a different rendering for the diff,
 868          * perhaps taking advantage of the content's native form. This is required for all content
 869          * models that are not text based.
 870          *
 871          * @since 1.21
 872          *
 873          * @param Content $old Old content
 874          * @param Content $new New content
 875          *
 876          * @throws MWException If old or new content is not an instance of TextContent.
 877          * @return bool|string
 878          */
 879         public function generateContentDiffBody( Content $old, Content $new ) {
 880                 if ( !( $old instanceof TextContent ) ) {
 881                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 882                                 "override generateContentDiffBody to fix this." );
 883                 }
 884
 885                 if ( !( $new instanceof TextContent ) ) {
 886                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 887                                 . "override generateContentDiffBody to fix this." );
 888                 }
 889
 890                 $otext = $old->serialize();
 891                 $ntext = $new->serialize();
 892
 893                 return $this->generateTextDiffBody( $otext, $ntext );
 894         }
 895
 896         /**
 897          * Generate a diff, no caching
 898          *
 899          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 900          *
 901          * @param string $otext Old text, must be already segmented
 902          * @param string $ntext New text, must be already segmented
 903          *
 904          * @return bool|string
 905          */
 906         public function generateTextDiffBody( $otext, $ntext ) {
 907                 $diff = function () use ( $otext, $ntext ) {
 908                         $time = microtime( true );
 909
 910                         $result = $this->textDiff( $otext, $ntext );
 911
 912                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 913                         MediaWikiServices::getInstance()->getStatsdDataFactory()->timing( 'diff_time', $time );
 914                         // Log requests slower than 99th percentile
 915                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 916                                 wfDebugLog( 'diff',
 917                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 918                         }
 919
 920                         return $result;
 921                 };
 922
 923                 /**
 924                  * @param Status $status
 925                  * @throws FatalError
 926                  */
 927                 $error = function ( $status ) {
 928                         throw new FatalError( $status->getWikiText() );
 929                 };
 930
 931                 // Use PoolCounter if the diff looks like it can be expensive
 932                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 933                         $work = new PoolCounterWorkViaCallback( 'diff',
 934                                 md5( $otext ) . md5( $ntext ),
 935                                 [ 'doWork' => $diff, 'error' => $error ]
 936                         );
 937                         return $work->execute();
 938                 }
 939
 940                 return $diff();
 941         }
 942
 943         /**
 944          * Process $wgExternalDiffEngine and get a sane, usable engine
 945          *
 946          * @return bool|string 'wikidiff2', path to an executable, or false
 947          */
 948         private function getEngine() {
 949                 global $wgExternalDiffEngine;
 950                 // We use the global here instead of Config because we write to the value,
 951                 // and Config is not mutable.
 952                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 953                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 954                         $wgExternalDiffEngine = false;
 955                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 956                         // Same as above, but with no deprecation warnings
 957                         $wgExternalDiffEngine = false;
 958                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 959                         // And prevent people from shooting themselves in the foot...
 960                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 961                         $wgExternalDiffEngine = false;
 962                 }
 963
 964                 if ( is_string( $wgExternalDiffEngine ) && is_executable( $wgExternalDiffEngine ) ) {
 965                         return $wgExternalDiffEngine;
 966                 } elseif ( $wgExternalDiffEngine === false && function_exists( 'wikidiff2_do_diff' ) ) {
 967                         return 'wikidiff2';
 968                 } else {
 969                         // Native PHP
 970                         return false;
 971                 }
 972         }
 973
 974         /**
 975          * Generates diff, to be wrapped internally in a logging/instrumentation
 976          *
 977          * @param string $otext Old text, must be already segmented
 978          * @param string $ntext New text, must be already segmented
 979          * @return bool|string
 980          */
 981         protected function textDiff( $otext, $ntext ) {
 982                 global $wgContLang;
 983
 984                 $otext = str_replace( "\r\n", "\n", $otext );
 985                 $ntext = str_replace( "\r\n", "\n", $ntext );
 986
 987                 $engine = $this->getEngine();
 988
 989                 // Better external diff engine, the 2 may some day be dropped
 990                 // This one does the escaping and segmenting itself
 991                 if ( $engine === 'wikidiff2' ) {
 992                         $wikidiff2Version = phpversion( 'wikidiff2' );
 993                         if (
 994                                 $wikidiff2Version !== false &&
 995                                 version_compare( $wikidiff2Version, '1.5.0', '>=' )
 996                         ) {
 997                                 $text = wikidiff2_do_diff(
 998                                         $otext,
 999                                         $ntext,
1000                                         2,
1001                                         $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' )
1002                                 );
1003                         } else {
1004                                 // Don't pass the 4th parameter for compatibility with older versions of wikidiff2
1005                                 $text = wikidiff2_do_diff(
1006                                         $otext,
1007                                         $ntext,
1008                                         2
1009                                 );
1010
1011                                 // Log a warning in case the configuration value is set to not silently ignore it
1012                                 if ( $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' ) > 0 ) {
1013                                         wfLogWarning( '$wgWikiDiff2MovedParagraphDetectionCutoff is set but has no
1014                                                 effect since the used version of WikiDiff2 does not support it.' );
1015                                 }
1016                         }
1017
1018                         $text .= $this->debug( 'wikidiff2' );
1019
1020                         return $text;
1021                 } elseif ( $engine !== false ) {
1022                         # Diff via the shell
1023                         $tmpDir = wfTempDir();
1024                         $tempName1 = tempnam( $tmpDir, 'diff_' );
1025                         $tempName2 = tempnam( $tmpDir, 'diff_' );
1026
1027                         $tempFile1 = fopen( $tempName1, "w" );
1028                         if ( !$tempFile1 ) {
1029                                 return false;
1030                         }
1031                         $tempFile2 = fopen( $tempName2, "w" );
1032                         if ( !$tempFile2 ) {
1033                                 return false;
1034                         }
1035                         fwrite( $tempFile1, $otext );
1036                         fwrite( $tempFile2, $ntext );
1037                         fclose( $tempFile1 );
1038                         fclose( $tempFile2 );
1039                         $cmd = [ $engine, $tempName1, $tempName2 ];
1040                         $result = Shell::command( $cmd )
1041                                 ->execute();
1042                         $exitCode = $result->getExitCode();
1043                         if ( $exitCode !== 0 ) {
1044                                 throw new Exception( "External diff command returned code {$exitCode}. Stderr: "
1045                                         . wfEscapeWikiText( $result->getStderr() )
1046                                 );
1047                         }
1048                         $difftext = $result->getStdout();
1049                         $difftext .= $this->debug( "external $engine" );
1050                         unlink( $tempName1 );
1051                         unlink( $tempName2 );
1052
1053                         return $difftext;
1054                 }
1055
1056                 # Native PHP diff
1057                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
1058                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
1059                 $diffs = new Diff( $ota, $nta );
1060                 $formatter = new TableDiffFormatter();
1061                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
1062                 $difftext .= $this->debug( 'native PHP' );
1063
1064                 return $difftext;
1065         }
1066
1067         /**
1068          * Generate a debug comment indicating diff generating time,
1069          * server node, and generator backend.
1070          *
1071          * @param string $generator : What diff engine was used
1072          *
1073          * @return string
1074          */
1075         protected function debug( $generator = "internal" ) {
1076                 global $wgShowHostnames;
1077                 if ( !$this->enableDebugComment ) {
1078                         return '';
1079                 }
1080                 $data = [ $generator ];
1081                 if ( $wgShowHostnames ) {
1082                         $data[] = wfHostname();
1083                 }
1084                 $data[] = wfTimestamp( TS_DB );
1085
1086                 return "<!-- diff generator: " .
1087                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1088                         " -->\n";
1089         }
1090
1091         /**
1092          * Localise diff output
1093          *
1094          * @param string $text
1095          * @return string
1096          */
1097         private function localiseDiff( $text ) {
1098                 $text = $this->localiseLineNumbers( $text );
1099                 if ( $this->getEngine() === 'wikidiff2' &&
1100                         version_compare( phpversion( 'wikidiff2' ), '1.5.1', '>=' )
1101                 ) {
1102                         $text = $this->addLocalisedTitleTooltips( $text );
1103                 }
1104                 return $text;
1105         }
1106
1107         /**
1108          * Replace line numbers with the text in the user's language
1109          *
1110          * @param string $text
1111          *
1112          * @return mixed
1113          */
1114         public function localiseLineNumbers( $text ) {
1115                 return preg_replace_callback(
1116                         '/<!--LINE (\d+)-->/',
1117                         [ $this, 'localiseLineNumbersCb' ],
1118                         $text
1119                 );
1120         }
1121
1122         public function localiseLineNumbersCb( $matches ) {
1123                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1124                         return '';
1125                 }
1126
1127                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1128         }
1129
1130         /**
1131          * Add title attributes for tooltips on moved paragraph indicators
1132          *
1133          * @param string $text
1134          * @return string
1135          */
1136         private function addLocalisedTitleTooltips( $text ) {
1137                 return preg_replace_callback(
1138                         '/class="mw-diff-movedpara-(left|right)"/',
1139                         [ $this, 'addLocalisedTitleTooltipsCb' ],
1140                         $text
1141                 );
1142         }
1143
1144         /**
1145          * @param array $matches
1146          * @return string
1147          */
1148         private function addLocalisedTitleTooltipsCb( array $matches ) {
1149                 $key = $matches[1] === 'right' ?
1150                         'diff-paragraph-moved-toold' :
1151                         'diff-paragraph-moved-tonew';
1152                 return $matches[0] . ' title="' . $this->msg( $key )->escaped() . '"';
1153         }
1154
1155         /**
1156          * If there are revisions between the ones being compared, return a note saying so.
1157          *
1158          * @return string
1159          */
1160         public function getMultiNotice() {
1161                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1162                         return '';
1163                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1164                         // Comparing two different pages? Count would be meaningless.
1165                         return '';
1166                 }
1167
1168                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1169                         $oldRev = $this->mNewRev; // flip
1170                         $newRev = $this->mOldRev; // flip
1171                 } else { // normal case
1172                         $oldRev = $this->mOldRev;
1173                         $newRev = $this->mNewRev;
1174                 }
1175
1176                 // Sanity: don't show the notice if too many rows must be scanned
1177                 // @todo show some special message for that case
1178                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1179                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1180                         $limit = 100; // use diff-multi-manyusers if too many users
1181                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1182                         $numUsers = count( $users );
1183
1184                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1185                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1186                         }
1187
1188                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1189                 }
1190
1191                 return ''; // nothing
1192         }
1193
1194         /**
1195          * Get a notice about how many intermediate edits and users there are
1196          *
1197          * @param int $numEdits
1198          * @param int $numUsers
1199          * @param int $limit
1200          *
1201          * @return string
1202          */
1203         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1204                 if ( $numUsers === 0 ) {
1205                         $msg = 'diff-multi-sameuser';
1206                 } elseif ( $numUsers > $limit ) {
1207                         $msg = 'diff-multi-manyusers';
1208                         $numUsers = $limit;
1209                 } else {
1210                         $msg = 'diff-multi-otherusers';
1211                 }
1212
1213                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1214         }
1215
1216         /**
1217          * Get a header for a specified revision.
1218          *
1219          * @param Revision $rev
1220          * @param string $complete 'complete' to get the header wrapped depending
1221          *        the visibility of the revision and a link to edit the page.
1222          *
1223          * @return string HTML fragment
1224          */
1225         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1226                 $lang = $this->getLanguage();
1227                 $user = $this->getUser();
1228                 $revtimestamp = $rev->getTimestamp();
1229                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1230                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1231                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1232
1233                 $header = $this->msg(
1234                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1235                         $timestamp,
1236                         $dateofrev,
1237                         $timeofrev
1238                 )->escaped();
1239
1240                 if ( $complete !== 'complete' ) {
1241                         return $header;
1242                 }
1243
1244                 $title = $rev->getTitle();
1245
1246                 $header = Linker::linkKnown( $title, $header, [],
1247                         [ 'oldid' => $rev->getId() ] );
1248
1249                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1250                         $editQuery = [ 'action' => 'edit' ];
1251                         if ( !$rev->isCurrent() ) {
1252                                 $editQuery['oldid'] = $rev->getId();
1253                         }
1254
1255                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1256                         $msg = $this->msg( $key )->escaped();
1257                         $editLink = $this->msg( 'parentheses' )->rawParams(
1258                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1259                         $header .= ' ' . Html::rawElement(
1260                                 'span',
1261                                 [ 'class' => 'mw-diff-edit' ],
1262                                 $editLink
1263                         );
1264                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1265                                 $header = Html::rawElement(
1266                                         'span',
1267                                         [ 'class' => 'history-deleted' ],
1268                                         $header
1269                                 );
1270                         }
1271                 } else {
1272                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1273                 }
1274
1275                 return $header;
1276         }
1277
1278         /**
1279          * Add the header to a diff body
1280          *
1281          * @param string $diff Diff body
1282          * @param string $otitle Old revision header
1283          * @param string $ntitle New revision header
1284          * @param string $multi Notice telling user that there are intermediate
1285          *   revisions between the ones being compared
1286          * @param string $notice Other notices, e.g. that user is viewing deleted content
1287          *
1288          * @return string
1289          */
1290         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1291                 // shared.css sets diff in interface language/dir, but the actual content
1292                 // is often in a different language, mostly the page content language/dir
1293                 $header = Html::openElement( 'table', [
1294                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1295                         'data-mw' => 'interface',
1296                 ] );
1297                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1298
1299                 if ( !$diff && !$otitle ) {
1300                         $header .= "
1301                         <tr class=\"diff-title\" lang=\"{$userLang}\">
1302                         <td class=\"diff-ntitle\">{$ntitle}</td>
1303                         </tr>";
1304                         $multiColspan = 1;
1305                 } else {
1306                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1307                                 $header .= "
1308                                 <col class=\"diff-marker\" />
1309                                 <col class=\"diff-content\" />
1310                                 <col class=\"diff-marker\" />
1311                                 <col class=\"diff-content\" />";
1312                                 $colspan = 2;
1313                                 $multiColspan = 4;
1314                         } else {
1315                                 $colspan = 1;
1316                                 $multiColspan = 2;
1317                         }
1318                         if ( $otitle || $ntitle ) {
1319                                 $header .= "
1320                                 <tr class=\"diff-title\" lang=\"{$userLang}\">
1321                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1322                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1323                                 </tr>";
1324                         }
1325                 }
1326
1327                 if ( $multi != '' ) {
1328                         $header .= "<tr><td colspan=\"{$multiColspan}\" " .
1329                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1330                 }
1331                 if ( $notice != '' ) {
1332                         $header .= "<tr><td colspan=\"{$multiColspan}\" " .
1333                                 "class=\"diff-notice\" lang=\"{$userLang}\">{$notice}</td></tr>";
1334                 }
1335
1336                 return $header . $diff . "</table>";
1337         }
1338
1339         /**
1340          * Use specified text instead of loading from the database
1341          * @param Content $oldContent
1342          * @param Content $newContent
1343          * @since 1.21
1344          */
1345         public function setContent( Content $oldContent, Content $newContent ) {
1346                 $this->mOldContent = $oldContent;
1347                 $this->mNewContent = $newContent;
1348
1349                 $this->mTextLoaded = 2;
1350                 $this->mRevisionsLoaded = true;
1351                 $this->isContentOverridden = true;
1352         }
1353
1354         /**
1355          * Set the language in which the diff text is written
1356          *
1357          * @param Language $lang
1358          * @since 1.19
1359          */
1360         public function setTextLanguage( $lang ) {
1361                 if ( !$lang instanceof Language ) {
1362                         wfDeprecated( __METHOD__ . ' with other type than Language for $lang', '1.32' );
1363                 }
1364                 $this->mDiffLang = wfGetLangObj( $lang );
1365         }
1366
1367         /**
1368          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1369          * to a pair of actual integers representing revision ids.
1370          *
1371          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1372          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1373          *
1374          * @return int[] List of two revision ids, older first, later second.
1375          *     Zero signifies invalid argument passed.
1376          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1377          */
1378         public function mapDiffPrevNext( $old, $new ) {
1379                 if ( $new === 'prev' ) {
1380                         // Show diff between revision $old and the previous one. Get previous one from DB.
1381                         $newid = intval( $old );
1382                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1383                 } elseif ( $new === 'next' ) {
1384                         // Show diff between revision $old and the next one. Get next one from DB.
1385                         $oldid = intval( $old );
1386                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1387                 } else {
1388                         $oldid = intval( $old );
1389                         $newid = intval( $new );
1390                 }
1391
1392                 return [ $oldid, $newid ];
1393         }
1394
1395         /**
1396          * Load revision IDs
1397          */
1398         private function loadRevisionIds() {
1399                 if ( $this->mRevisionsIdsLoaded ) {
1400                         return;
1401                 }
1402
1403                 $this->mRevisionsIdsLoaded = true;
1404
1405                 $old = $this->mOldid;
1406                 $new = $this->mNewid;
1407
1408                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1409                 if ( $new === 'next' && $this->mNewid === false ) {
1410                         # if no result, NewId points to the newest old revision. The only newer
1411                         # revision is cur, which is "0".
1412                         $this->mNewid = 0;
1413                 }
1414
1415                 Hooks::run(
1416                         'NewDifferenceEngine',
1417                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1418                 );
1419         }
1420
1421         /**
1422          * Load revision metadata for the specified articles. If newid is 0, then compare
1423          * the old article in oldid to the current article; if oldid is 0, then
1424          * compare the current article to the immediately previous one (ignoring the
1425          * value of newid).
1426          *
1427          * If oldid is false, leave the corresponding revision object set
1428          * to false. This is impossible via ordinary user input, and is provided for
1429          * API convenience.
1430          *
1431          * @return bool Whether both revisions were loaded successfully.
1432          */
1433         public function loadRevisionData() {
1434                 if ( $this->mRevisionsLoaded ) {
1435                         return $this->isContentOverridden || $this->mNewRev && $this->mOldRev;
1436                 }
1437
1438                 // Whether it succeeds or fails, we don't want to try again
1439                 $this->mRevisionsLoaded = true;
1440
1441                 $this->loadRevisionIds();
1442
1443                 // Load the new revision object
1444                 if ( $this->mNewid ) {
1445                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1446                 } else {
1447                         $this->mNewRev = Revision::newFromTitle(
1448                                 $this->getTitle(),
1449                                 false,
1450                                 Revision::READ_NORMAL
1451                         );
1452                 }
1453
1454                 if ( !$this->mNewRev instanceof Revision ) {
1455                         return false;
1456                 }
1457
1458                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1459                 $this->mNewid = $this->mNewRev->getId();
1460                 $this->mNewPage = $this->mNewRev->getTitle();
1461
1462                 // Load the old revision object
1463                 $this->mOldRev = false;
1464                 if ( $this->mOldid ) {
1465                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1466                 } elseif ( $this->mOldid === 0 ) {
1467                         $rev = $this->mNewRev->getPrevious();
1468                         if ( $rev ) {
1469                                 $this->mOldid = $rev->getId();
1470                                 $this->mOldRev = $rev;
1471                         } else {
1472                                 // No previous revision; mark to show as first-version only.
1473                                 $this->mOldid = false;
1474                                 $this->mOldRev = false;
1475                         }
1476                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1477
1478                 if ( is_null( $this->mOldRev ) ) {
1479                         return false;
1480                 }
1481
1482                 if ( $this->mOldRev ) {
1483                         $this->mOldPage = $this->mOldRev->getTitle();
1484                 }
1485
1486                 // Load tags information for both revisions
1487                 $dbr = wfGetDB( DB_REPLICA );
1488                 if ( $this->mOldid !== false ) {
1489                         $this->mOldTags = $dbr->selectField(
1490                                 'tag_summary',
1491                                 'ts_tags',
1492                                 [ 'ts_rev_id' => $this->mOldid ],
1493                                 __METHOD__
1494                         );
1495                 } else {
1496                         $this->mOldTags = false;
1497                 }
1498                 $this->mNewTags = $dbr->selectField(
1499                         'tag_summary',
1500                         'ts_tags',
1501                         [ 'ts_rev_id' => $this->mNewid ],
1502                         __METHOD__
1503                 );
1504
1505                 return true;
1506         }
1507
1508         /**
1509          * Load the text of the revisions, as well as revision data.
1510          *
1511          * @return bool Whether the content of both revisions could be loaded successfully.
1512          */
1513         public function loadText() {
1514                 if ( $this->mTextLoaded == 2 ) {
1515                         return $this->loadRevisionData() && $this->mOldContent && $this->mNewContent;
1516                 }
1517
1518                 // Whether it succeeds or fails, we don't want to try again
1519                 $this->mTextLoaded = 2;
1520
1521                 if ( !$this->loadRevisionData() ) {
1522                         return false;
1523                 }
1524
1525                 if ( $this->mOldRev ) {
1526                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1527                         if ( $this->mOldContent === null ) {
1528                                 return false;
1529                         }
1530                 }
1531
1532                 if ( $this->mNewRev ) {
1533                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1534                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1535                         if ( $this->mNewContent === null ) {
1536                                 return false;
1537                         }
1538                 }
1539
1540                 return true;
1541         }
1542
1543         /**
1544          * Load the text of the new revision, not the old one
1545          *
1546          * @return bool Whether the content of the new revision could be loaded successfully.
1547          */
1548         public function loadNewText() {
1549                 if ( $this->mTextLoaded >= 1 ) {
1550                         return $this->loadRevisionData();
1551                 }
1552
1553                 $this->mTextLoaded = 1;
1554
1555                 if ( !$this->loadRevisionData() ) {
1556                         return false;
1557                 }
1558
1559                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1560
1561                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1562
1563                 return true;
1564         }
1565
1566 }