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 /** @deprecated use class constant instead */
  27 define( 'MW_DIFF_VERSION', '1.11a' );
  28
  29 /**
  30  * @todo document
  31  * @ingroup DifferenceEngine
  32  */
  33 class DifferenceEngine extends ContextSource {
  34         /**
  35          * Constant to indicate diff cache compatibility.
  36          * Bump this when changing the diff formatting in a way that
  37          * fixes important bugs or such to force cached diff views to
  38          * clear.
  39          */
  40         const DIFF_VERSION = MW_DIFF_VERSION;
  41
  42         /** @var int */
  43         public $mOldid;
  44
  45         /** @var int */
  46         public $mNewid;
  47
  48         private $mOldTags;
  49         private $mNewTags;
  50
  51         /** @var Content */
  52         public $mOldContent;
  53
  54         /** @var Content */
  55         public $mNewContent;
  56
  57         /** @var Language */
  58         protected $mDiffLang;
  59
  60         /** @var Title */
  61         public $mOldPage;
  62
  63         /** @var Title */
  64         public $mNewPage;
  65
  66         /** @var Revision */
  67         public $mOldRev;
  68
  69         /** @var Revision */
  70         public $mNewRev;
  71
  72         /** @var bool Have the revisions IDs been loaded */
  73         private $mRevisionsIdsLoaded = false;
  74
  75         /** @var bool Have the revisions been loaded */
  76         public $mRevisionsLoaded = false;
  77
  78         /** @var int How many text blobs have been loaded, 0, 1 or 2? */
  79         public $mTextLoaded = 0;
  80
  81         /** @var bool Was the diff fetched from cache? */
  82         public $mCacheHit = false;
  83
  84         /**
  85          * Set this to true to add debug info to the HTML output.
  86          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  87          * (T22601)
  88          */
  89         public $enableDebugComment = false;
  90
  91         /** @var bool If true, line X is not displayed when X is 1, for example
  92          *    to increase readability and conserve space with many small diffs.
  93          */
  94         protected $mReducedLineNumbers = false;
  95
  96         /** @var string Link to action=markpatrolled */
  97         protected $mMarkPatrolledLink = null;
  98
  99         /** @var bool Show rev_deleted content if allowed */
 100         protected $unhide = false;
 101
 102         /** @var bool Refresh the diff cache */
 103         protected $mRefreshCache = false;
 104
 105         /**#@-*/
 106
 107         /**
 108          * @param IContextSource $context Context to use, anything else will be ignored
 109          * @param int $old Old ID we want to show and diff with.
 110          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 111          * @param int $rcid Deprecated, no longer used!
 112          * @param bool $refreshCache If set, refreshes the diff cache
 113          * @param bool $unhide If set, allow viewing deleted revs
 114          */
 115         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 116                 $refreshCache = false, $unhide = false
 117         ) {
 118                 if ( $context instanceof IContextSource ) {
 119                         $this->setContext( $context );
 120                 }
 121
 122                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 123
 124                 $this->mOldid = $old;
 125                 $this->mNewid = $new;
 126                 $this->mRefreshCache = $refreshCache;
 127                 $this->unhide = $unhide;
 128         }
 129
 130         /**
 131          * @param bool $value
 132          */
 133         public function setReducedLineNumbers( $value = true ) {
 134                 $this->mReducedLineNumbers = $value;
 135         }
 136
 137         /**
 138          * @return Language
 139          */
 140         public function getDiffLang() {
 141                 if ( $this->mDiffLang === null ) {
 142                         # Default language in which the diff text is written.
 143                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 144                 }
 145
 146                 return $this->mDiffLang;
 147         }
 148
 149         /**
 150          * @return bool
 151          */
 152         public function wasCacheHit() {
 153                 return $this->mCacheHit;
 154         }
 155
 156         /**
 157          * @return int
 158          */
 159         public function getOldid() {
 160                 $this->loadRevisionIds();
 161
 162                 return $this->mOldid;
 163         }
 164
 165         /**
 166          * @return bool|int
 167          */
 168         public function getNewid() {
 169                 $this->loadRevisionIds();
 170
 171                 return $this->mNewid;
 172         }
 173
 174         /**
 175          * Look up a special:Undelete link to the given deleted revision id,
 176          * as a workaround for being unable to load deleted diffs in currently.
 177          *
 178          * @param int $id Revision ID
 179          *
 180          * @return string|bool Link HTML or false
 181          */
 182         public function deletedLink( $id ) {
 183                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 184                         $dbr = wfGetDB( DB_REPLICA );
 185                         $row = $dbr->selectRow( 'archive',
 186                                 array_merge(
 187                                         Revision::selectArchiveFields(),
 188                                         [ 'ar_namespace', 'ar_title' ]
 189                                 ),
 190                                 [ 'ar_rev_id' => $id ],
 191                                 __METHOD__ );
 192                         if ( $row ) {
 193                                 $rev = Revision::newFromArchiveRow( $row );
 194                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 195
 196                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
 197                                         'target' => $title->getPrefixedText(),
 198                                         'timestamp' => $rev->getTimestamp()
 199                                 ] );
 200                         }
 201                 }
 202
 203                 return false;
 204         }
 205
 206         /**
 207          * Build a wikitext link toward a deleted revision, if viewable.
 208          *
 209          * @param int $id Revision ID
 210          *
 211          * @return string Wikitext fragment
 212          */
 213         public function deletedIdMarker( $id ) {
 214                 $link = $this->deletedLink( $id );
 215                 if ( $link ) {
 216                         return "[$link $id]";
 217                 } else {
 218                         return (string)$id;
 219                 }
 220         }
 221
 222         private function showMissingRevision() {
 223                 $out = $this->getOutput();
 224
 225                 $missing = [];
 226                 if ( $this->mOldRev === null ||
 227                         ( $this->mOldRev && $this->mOldContent === null )
 228                 ) {
 229                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 230                 }
 231                 if ( $this->mNewRev === null ||
 232                         ( $this->mNewRev && $this->mNewContent === null )
 233                 ) {
 234                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 235                 }
 236
 237                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 238                 $msg = $this->msg( 'difference-missing-revision' )
 239                         ->params( $this->getLanguage()->listToText( $missing ) )
 240                         ->numParams( count( $missing ) )
 241                         ->parseAsBlock();
 242                 $out->addHTML( $msg );
 243         }
 244
 245         public function showDiffPage( $diffOnly = false ) {
 246                 # Allow frames except in certain special cases
 247                 $out = $this->getOutput();
 248                 $out->allowClickjacking();
 249                 $out->setRobotPolicy( 'noindex,nofollow' );
 250
 251                 // Allow extensions to add any extra output here
 252                 Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
 253
 254                 if ( !$this->loadRevisionData() ) {
 255                         if ( Hooks::run( 'DifferenceEngineShowDiffPageMaybeShowMissingRevision', [ $this ] ) ) {
 256                                 $this->showMissingRevision();
 257                         }
 258                         return;
 259                 }
 260
 261                 $user = $this->getUser();
 262                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 263                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 264                         $permErrors = wfMergeErrorArrays( $permErrors,
 265                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 266                 }
 267                 if ( count( $permErrors ) ) {
 268                         throw new PermissionsError( 'read', $permErrors );
 269                 }
 270
 271                 $rollback = '';
 272
 273                 $query = [];
 274                 # Carry over 'diffonly' param via navigation links
 275                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 276                         $query['diffonly'] = $diffOnly;
 277                 }
 278                 # Cascade unhide param in links for easy deletion browsing
 279                 if ( $this->unhide ) {
 280                         $query['unhide'] = 1;
 281                 }
 282
 283                 # Check if one of the revisions is deleted/suppressed
 284                 $deleted = $suppressed = false;
 285                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 286
 287                 $revisionTools = [];
 288
 289                 # mOldRev is false if the difference engine is called with a "vague" query for
 290                 # a diff between a version V and its previous version V' AND the version V
 291                 # is the first version of that article. In that case, V' does not exist.
 292                 if ( $this->mOldRev === false ) {
 293                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 294                         $samePage = true;
 295                         $oldHeader = '';
 296                         // Allow extensions to change the $oldHeader variable
 297                         Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
 298                 } else {
 299                         Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 300
 301                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 302                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 303                                 $samePage = true;
 304                         } else {
 305                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 306                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 307                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 308                                 $samePage = false;
 309                         }
 310
 311                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 312                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 313                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 314                                         if ( $rollbackLink ) {
 315                                                 $out->preventClickjacking();
 316                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 317                                         }
 318                                 }
 319
 320                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 321                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 322                                 ) {
 323                                         $undoLink = Html::element( 'a', [
 324                                                         'href' => $this->mNewPage->getLocalURL( [
 325                                                                 'action' => 'edit',
 326                                                                 'undoafter' => $this->mOldid,
 327                                                                 'undo' => $this->mNewid
 328                                                         ] ),
 329                                                         'title' => Linker::titleAttrib( 'undo' ),
 330                                                 ],
 331                                                 $this->msg( 'editundo' )->text()
 332                                         );
 333                                         $revisionTools['mw-diff-undo'] = $undoLink;
 334                                 }
 335                         }
 336
 337                         # Make "previous revision link"
 338                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 339                                 $prevlink = Linker::linkKnown(
 340                                         $this->mOldPage,
 341                                         $this->msg( 'previousdiff' )->escaped(),
 342                                         [ 'id' => 'differences-prevlink' ],
 343                                         [ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
 344                                 );
 345                         } else {
 346                                 $prevlink = '&#160;';
 347                         }
 348
 349                         if ( $this->mOldRev->isMinor() ) {
 350                                 $oldminor = ChangesList::flag( 'minor' );
 351                         } else {
 352                                 $oldminor = '';
 353                         }
 354
 355                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 356                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 357                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );
 358
 359                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 360                                 '<div id="mw-diff-otitle2">' .
 361                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 362                                 '<div id="mw-diff-otitle3">' . $oldminor .
 363                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 364                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 365                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 366
 367                         // Allow extensions to change the $oldHeader variable
 368                         Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
 369                                 $diffOnly, $ldel, $this->unhide ] );
 370
 371                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 372                                 $deleted = true; // old revisions text is hidden
 373                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 374                                         $suppressed = true; // also suppressed
 375                                 }
 376                         }
 377
 378                         # Check if this user can see the revisions
 379                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 380                                 $allowed = false;
 381                         }
 382                 }
 383
 384                 $out->addJsConfigVars( [
 385                         'wgDiffOldId' => $this->mOldid,
 386                         'wgDiffNewId' => $this->mNewid,
 387                 ] );
 388
 389                 # Make "next revision link"
 390                 # Skip next link on the top revision
 391                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 392                         $nextlink = Linker::linkKnown(
 393                                 $this->mNewPage,
 394                                 $this->msg( 'nextdiff' )->escaped(),
 395                                 [ 'id' => 'differences-nextlink' ],
 396                                 [ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
 397                         );
 398                 } else {
 399                         $nextlink = '&#160;';
 400                 }
 401
 402                 if ( $this->mNewRev->isMinor() ) {
 403                         $newminor = ChangesList::flag( 'minor' );
 404                 } else {
 405                         $newminor = '';
 406                 }
 407
 408                 # Handle RevisionDelete links...
 409                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 410
 411                 # Allow extensions to define their own revision tools
 412                 Hooks::run( 'DiffRevisionTools',
 413                         [ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
 414                 $formattedRevisionTools = [];
 415                 // Put each one in parentheses (poor man's button)
 416                 foreach ( $revisionTools as $key => $tool ) {
 417                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 418                         $element = Html::rawElement(
 419                                 'span',
 420                                 [ 'class' => $toolClass ],
 421                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 422                         );
 423                         $formattedRevisionTools[] = $element;
 424                 }
 425                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 426                         ' ' . implode( ' ', $formattedRevisionTools );
 427                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );
 428
 429                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 430                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 431                         " $rollback</div>" .
 432                         '<div id="mw-diff-ntitle3">' . $newminor .
 433                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 434                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 435                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 436
 437                 // Allow extensions to change the $newHeader variable
 438                 Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
 439                         $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
 440
 441                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 442                         $deleted = true; // new revisions text is hidden
 443                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 444                                 $suppressed = true; // also suppressed
 445                         }
 446                 }
 447
 448                 # If the diff cannot be shown due to a deleted revision, then output
 449                 # the diff header and links to unhide (if available)...
 450                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 451                         $this->showDiffStyle();
 452                         $multi = $this->getMultiNotice();
 453                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 454                         if ( !$allowed ) {
 455                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 456                                 # Give explanation for why revision is not visible
 457                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 458                                         [ $msg ] );
 459                         } else {
 460                                 # Give explanation and add a link to view the diff...
 461                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
 462                                 $link = $this->getTitle()->getFullURL( $query );
 463                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 464                                 $out->wrapWikiMsg(
 465                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 466                                         [ $msg, $link ]
 467                                 );
 468                         }
 469                 # Otherwise, output a regular diff...
 470                 } else {
 471                         # Add deletion notice if the user is viewing deleted content
 472                         $notice = '';
 473                         if ( $deleted ) {
 474                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 475                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 476                                         $this->msg( $msg )->parse() .
 477                                         "</div>\n";
 478                         }
 479                         $this->showDiff( $oldHeader, $newHeader, $notice );
 480                         if ( !$diffOnly ) {
 481                                 $this->renderNewRevision();
 482                         }
 483                 }
 484         }
 485
 486         /**
 487          * Build a link to mark a change as patrolled.
 488          *
 489          * Returns empty string if there's either no revision to patrol or the user is not allowed to.
 490          * Side effect: When the patrol link is build, this method will call
 491          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 492          *
 493          * @return string HTML or empty string
 494          */
 495         public function markPatrolledLink() {
 496                 if ( $this->mMarkPatrolledLink === null ) {
 497                         $linkInfo = $this->getMarkPatrolledLinkInfo();
 498                         // If false, there is no patrol link needed/allowed
 499                         if ( !$linkInfo ) {
 500                                 $this->mMarkPatrolledLink = '';
 501                         } else {
 502                                 $this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
 503                                         Linker::linkKnown(
 504                                                 $this->mNewPage,
 505                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 506                                                 [],
 507                                                 [
 508                                                         'action' => 'markpatrolled',
 509                                                         'rcid' => $linkInfo['rcid'],
 510                                                 ]
 511                                         ) . ']</span>';
 512                                 // Allow extensions to change the markpatrolled link
 513                                 Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
 514                                         &$this->mMarkPatrolledLink, $linkInfo['rcid'] ] );
 515                         }
 516                 }
 517                 return $this->mMarkPatrolledLink;
 518         }
 519
 520         /**
 521          * Returns an array of meta data needed to build a "mark as patrolled" link and
 522          * adds the mediawiki.page.patrol.ajax to the output.
 523          *
 524          * @return array|false An array of meta data for a patrol link (rcid only)
 525          *  or false if no link is needed
 526          */
 527         protected function getMarkPatrolledLinkInfo() {
 528                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 529
 530                 $user = $this->getUser();
 531
 532                 // Prepare a change patrol link, if applicable
 533                 if (
 534                         // Is patrolling enabled and the user allowed to?
 535                         $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 536                         // Only do this if the revision isn't more than 6 hours older
 537                         // than the Max RC age (6h because the RC might not be cleaned out regularly)
 538                         RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 539                 ) {
 540                         // Look for an unpatrolled change corresponding to this diff
 541                         $db = wfGetDB( DB_REPLICA );
 542                         $change = RecentChange::newFromConds(
 543                                 [
 544                                         'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 545                                         'rc_this_oldid' => $this->mNewid,
 546                                         'rc_patrolled' => 0
 547                                 ],
 548                                 __METHOD__
 549                         );
 550
 551                         if ( $change && !$change->getPerformer()->equals( $user ) ) {
 552                                 $rcid = $change->getAttribute( 'rc_id' );
 553                         } else {
 554                                 // None found or the page has been created by the current user.
 555                                 // If the user could patrol this it already would be patrolled
 556                                 $rcid = 0;
 557                         }
 558
 559                         // Allow extensions to possibly change the rcid here
 560                         // For example the rcid might be set to zero due to the user
 561                         // being the same as the performer of the change but an extension
 562                         // might still want to show it under certain conditions
 563                         Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
 564
 565                         // Build the link
 566                         if ( $rcid ) {
 567                                 $this->getOutput()->preventClickjacking();
 568                                 if ( $wgEnableAPI && $wgEnableWriteAPI
 569                                         && $user->isAllowed( 'writeapi' )
 570                                 ) {
 571                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 572                                 }
 573
 574                                 return [
 575                                         'rcid' => $rcid,
 576                                 ];
 577                         }
 578                 }
 579
 580                 // No mark as patrolled link applicable
 581                 return false;
 582         }
 583
 584         /**
 585          * @param Revision $rev
 586          *
 587          * @return string
 588          */
 589         protected function revisionDeleteLink( $rev ) {
 590                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 591                 if ( $link !== '' ) {
 592                         $link = '&#160;&#160;&#160;' . $link . ' ';
 593                 }
 594
 595                 return $link;
 596         }
 597
 598         /**
 599          * Show the new revision of the page.
 600          */
 601         public function renderNewRevision() {
 602                 $out = $this->getOutput();
 603                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 604                 # Add "current version as of X" title
 605                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 606                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 607                 # Page content may be handled by a hooked call instead...
 608                 # @codingStandardsIgnoreStart Ignoring long lines.
 609                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 610                         $this->loadNewText();
 611                         $out->setRevisionId( $this->mNewid );
 612                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 613                         $out->setArticleFlag( true );
 614
 615                         if ( !Hooks::run( 'ArticleContentViewCustom', [ $this->mNewContent, $this->mNewPage, $out ] ) ) {
 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', [ $this, $out, $parserOutput, $wikiPage ] ) ) {
 635                                                 $out->addParserOutput( $parserOutput );
 636                                         }
 637                                 }
 638                         }
 639                 }
 640                 # @codingStandardsIgnoreEnd
 641
 642                 // Allow extensions to optionally not show the final patrolled link
 643                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 644                         # Add redundant patrol link on bottom...
 645                         $out->addHTML( $this->markPatrolledLink() );
 646                 }
 647         }
 648
 649         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 650                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 651
 652                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 653                         $parserOptions->setEditSection( false );
 654                 }
 655
 656                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 657
 658                 return $parserOutput;
 659         }
 660
 661         /**
 662          * Get the diff text, send it to the OutputPage object
 663          * Returns false if the diff could not be generated, otherwise returns true
 664          *
 665          * @param string|bool $otitle Header for old text or false
 666          * @param string|bool $ntitle Header for new text or false
 667          * @param string $notice HTML between diff header and body
 668          *
 669          * @return bool
 670          */
 671         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 672                 // Allow extensions to affect the output here
 673                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 674
 675                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 676                 if ( $diff === false ) {
 677                         $this->showMissingRevision();
 678
 679                         return false;
 680                 } else {
 681                         $this->showDiffStyle();
 682                         $this->getOutput()->addHTML( $diff );
 683
 684                         return true;
 685                 }
 686         }
 687
 688         /**
 689          * Add style sheets for diff display.
 690          */
 691         public function showDiffStyle() {
 692                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 693         }
 694
 695         /**
 696          * Get complete diff table, including header
 697          *
 698          * @param string|bool $otitle Header for old text or false
 699          * @param string|bool $ntitle Header for new text or false
 700          * @param string $notice HTML between diff header and body
 701          *
 702          * @return mixed
 703          */
 704         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 705                 $body = $this->getDiffBody();
 706                 if ( $body === false ) {
 707                         return false;
 708                 }
 709
 710                 $multi = $this->getMultiNotice();
 711                 // Display a message when the diff is empty
 712                 if ( $body === '' ) {
 713                         $notice .= '<div class="mw-diff-empty">' .
 714                                 $this->msg( 'diff-empty' )->parse() .
 715                                 "</div>\n";
 716                 }
 717
 718                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 719         }
 720
 721         /**
 722          * Get the diff table body, without header
 723          *
 724          * @return mixed (string/false)
 725          */
 726         public function getDiffBody() {
 727                 $this->mCacheHit = true;
 728                 // Check if the diff should be hidden from this user
 729                 if ( !$this->loadRevisionData() ) {
 730                         return false;
 731                 } elseif ( $this->mOldRev &&
 732                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 733                 ) {
 734                         return false;
 735                 } elseif ( $this->mNewRev &&
 736                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 737                 ) {
 738                         return false;
 739                 }
 740                 // Short-circuit
 741                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 742                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 743                 ) {
 744                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 745                                 return '';
 746                         }
 747                 }
 748                 // Cacheable?
 749                 $key = false;
 750                 $cache = ObjectCache::getMainWANInstance();
 751                 if ( $this->mOldid && $this->mNewid ) {
 752                         $key = $this->getDiffBodyCacheKey();
 753
 754                         // Try cache
 755                         if ( !$this->mRefreshCache ) {
 756                                 $difftext = $cache->get( $key );
 757                                 if ( $difftext ) {
 758                                         wfIncrStats( 'diff_cache.hit' );
 759                                         $difftext = $this->localiseLineNumbers( $difftext );
 760                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 761
 762                                         return $difftext;
 763                                 }
 764                         } // don't try to load but save the result
 765                 }
 766                 $this->mCacheHit = false;
 767
 768                 // Loadtext is permission safe, this just clears out the diff
 769                 if ( !$this->loadText() ) {
 770                         return false;
 771                 }
 772
 773                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 774
 775                 // Avoid PHP 7.1 warning from passing $this by reference
 776                 $diffEngine = $this;
 777
 778                 // Save to cache for 7 days
 779                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 780                         wfIncrStats( 'diff_cache.uncacheable' );
 781                 } elseif ( $key !== false && $difftext !== false ) {
 782                         wfIncrStats( 'diff_cache.miss' );
 783                         $cache->set( $key, $difftext, 7 * 86400 );
 784                 } else {
 785                         wfIncrStats( 'diff_cache.uncacheable' );
 786                 }
 787                 // Replace line numbers with the text in the user's language
 788                 if ( $difftext !== false ) {
 789                         $difftext = $this->localiseLineNumbers( $difftext );
 790                 }
 791
 792                 return $difftext;
 793         }
 794
 795         /**
 796          * Returns the cache key for diff body text or content.
 797          *
 798          * @since 1.23
 799          *
 800          * @throws MWException
 801          * @return string
 802          */
 803         protected function getDiffBodyCacheKey() {
 804                 if ( !$this->mOldid || !$this->mNewid ) {
 805                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 806                 }
 807
 808                 return wfMemcKey( 'diff', 'version', self::DIFF_VERSION,
 809                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 810         }
 811
 812         /**
 813          * Generate a diff, no caching.
 814          *
 815          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 816          * serialization of the given Content objects. This will fail if $old or $new are not
 817          * instances of TextContent.
 818          *
 819          * Subclasses may override this to provide a different rendering for the diff,
 820          * perhaps taking advantage of the content's native form. This is required for all content
 821          * models that are not text based.
 822          *
 823          * @since 1.21
 824          *
 825          * @param Content $old Old content
 826          * @param Content $new New content
 827          *
 828          * @throws MWException If old or new content is not an instance of TextContent.
 829          * @return bool|string
 830          */
 831         public function generateContentDiffBody( Content $old, Content $new ) {
 832                 if ( !( $old instanceof TextContent ) ) {
 833                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 834                                 "override generateContentDiffBody to fix this." );
 835                 }
 836
 837                 if ( !( $new instanceof TextContent ) ) {
 838                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 839                                 . "override generateContentDiffBody to fix this." );
 840                 }
 841
 842                 $otext = $old->serialize();
 843                 $ntext = $new->serialize();
 844
 845                 return $this->generateTextDiffBody( $otext, $ntext );
 846         }
 847
 848         /**
 849          * Generate a diff, no caching
 850          *
 851          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 852          *
 853          * @param string $otext Old text, must be already segmented
 854          * @param string $ntext New text, must be already segmented
 855          *
 856          * @return bool|string
 857          */
 858         public function generateTextDiffBody( $otext, $ntext ) {
 859                 $diff = function () use ( $otext, $ntext ) {
 860                         $time = microtime( true );
 861
 862                         $result = $this->textDiff( $otext, $ntext );
 863
 864                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 865                         MediaWikiServices::getInstance()->getStatsdDataFactory()->timing( 'diff_time', $time );
 866                         // Log requests slower than 99th percentile
 867                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 868                                 wfDebugLog( 'diff',
 869                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 870                         }
 871
 872                         return $result;
 873                 };
 874
 875                 /**
 876                  * @param Status $status
 877                  * @throws FatalError
 878                  */
 879                 $error = function ( $status ) {
 880                         throw new FatalError( $status->getWikiText() );
 881                 };
 882
 883                 // Use PoolCounter if the diff looks like it can be expensive
 884                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 885                         $work = new PoolCounterWorkViaCallback( 'diff',
 886                                 md5( $otext ) . md5( $ntext ),
 887                                 [ 'doWork' => $diff, 'error' => $error ]
 888                         );
 889                         return $work->execute();
 890                 }
 891
 892                 return $diff();
 893         }
 894
 895         /**
 896          * Generates diff, to be wrapped internally in a logging/instrumentation
 897          *
 898          * @param string $otext Old text, must be already segmented
 899          * @param string $ntext New text, must be already segmented
 900          * @return bool|string
 901          */
 902         protected function textDiff( $otext, $ntext ) {
 903                 global $wgExternalDiffEngine, $wgContLang;
 904
 905                 $otext = str_replace( "\r\n", "\n", $otext );
 906                 $ntext = str_replace( "\r\n", "\n", $ntext );
 907
 908                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 909                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 910                         $wgExternalDiffEngine = false;
 911                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 912                         // Same as above, but with no deprecation warnings
 913                         $wgExternalDiffEngine = false;
 914                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 915                         // And prevent people from shooting themselves in the foot...
 916                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 917                         $wgExternalDiffEngine = false;
 918                 }
 919
 920                 // Better external diff engine, the 2 may some day be dropped
 921                 // This one does the escaping and segmenting itself
 922                 if ( function_exists( 'wikidiff2_do_diff' ) && $wgExternalDiffEngine === false ) {
 923                         $wikidiff2Version = phpversion( 'wikidiff2' );
 924                         if (
 925                                 $wikidiff2Version !== false &&
 926                                 version_compare( $wikidiff2Version, '0.3', '>=' )
 927                         ) {
 928                                 $text = wikidiff2_do_diff(
 929                                         $otext,
 930                                         $ntext,
 931                                         2,
 932                                         $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' )
 933                                 );
 934                         } else {
 935                                 // Don't pass the 4th parameter for compatibility with older versions of wikidiff2
 936                                 $text = wikidiff2_do_diff(
 937                                         $otext,
 938                                         $ntext,
 939                                         2
 940                                 );
 941
 942                                 // Log a warning in case the configuration value is set to not silently ignore it
 943                                 if ( $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' ) > 0 ) {
 944                                         wfLogWarning( '$wgWikiDiff2MovedParagraphDetectionCutoff is set but has no
 945                                                 effect since the used version of WikiDiff2 does not support it.' );
 946                                 }
 947                         }
 948
 949                         $text .= $this->debug( 'wikidiff2' );
 950
 951                         return $text;
 952                 } elseif ( $wgExternalDiffEngine !== false && is_executable( $wgExternalDiffEngine ) ) {
 953                         # Diff via the shell
 954                         $tmpDir = wfTempDir();
 955                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 956                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 957
 958                         $tempFile1 = fopen( $tempName1, "w" );
 959                         if ( !$tempFile1 ) {
 960                                 return false;
 961                         }
 962                         $tempFile2 = fopen( $tempName2, "w" );
 963                         if ( !$tempFile2 ) {
 964                                 return false;
 965                         }
 966                         fwrite( $tempFile1, $otext );
 967                         fwrite( $tempFile2, $ntext );
 968                         fclose( $tempFile1 );
 969                         fclose( $tempFile2 );
 970                         $cmd = [ $wgExternalDiffEngine, $tempName1, $tempName2 ];
 971                         $result = Shell::command( $cmd )
 972                                 ->execute();
 973                         $exitCode = $result->getExitCode();
 974                         if ( $exitCode !== 0 ) {
 975                                 throw new Exception( "External diff command returned code {$exitCode}. Stderr: "
 976                                         . wfEscapeWikiText( $result->getStderr() )
 977                                 );
 978                         }
 979                         $difftext = $result->getStdout();
 980                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 981                         unlink( $tempName1 );
 982                         unlink( $tempName2 );
 983
 984                         return $difftext;
 985                 }
 986
 987                 # Native PHP diff
 988                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 989                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 990                 $diffs = new Diff( $ota, $nta );
 991                 $formatter = new TableDiffFormatter();
 992                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 993
 994                 return $difftext;
 995         }
 996
 997         /**
 998          * Generate a debug comment indicating diff generating time,
 999          * server node, and generator backend.
1000          *
1001          * @param string $generator : What diff engine was used
1002          *
1003          * @return string
1004          */
1005         protected function debug( $generator = "internal" ) {
1006                 global $wgShowHostnames;
1007                 if ( !$this->enableDebugComment ) {
1008                         return '';
1009                 }
1010                 $data = [ $generator ];
1011                 if ( $wgShowHostnames ) {
1012                         $data[] = wfHostname();
1013                 }
1014                 $data[] = wfTimestamp( TS_DB );
1015
1016                 return "<!-- diff generator: " .
1017                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1018                         " -->\n";
1019         }
1020
1021         /**
1022          * Replace line numbers with the text in the user's language
1023          *
1024          * @param string $text
1025          *
1026          * @return mixed
1027          */
1028         public function localiseLineNumbers( $text ) {
1029                 return preg_replace_callback(
1030                         '/<!--LINE (\d+)-->/',
1031                         [ $this, 'localiseLineNumbersCb' ],
1032                         $text
1033                 );
1034         }
1035
1036         public function localiseLineNumbersCb( $matches ) {
1037                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1038                         return '';
1039                 }
1040
1041                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1042         }
1043
1044         /**
1045          * If there are revisions between the ones being compared, return a note saying so.
1046          *
1047          * @return string
1048          */
1049         public function getMultiNotice() {
1050                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1051                         return '';
1052                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1053                         // Comparing two different pages? Count would be meaningless.
1054                         return '';
1055                 }
1056
1057                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1058                         $oldRev = $this->mNewRev; // flip
1059                         $newRev = $this->mOldRev; // flip
1060                 } else { // normal case
1061                         $oldRev = $this->mOldRev;
1062                         $newRev = $this->mNewRev;
1063                 }
1064
1065                 // Sanity: don't show the notice if too many rows must be scanned
1066                 // @todo show some special message for that case
1067                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1068                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1069                         $limit = 100; // use diff-multi-manyusers if too many users
1070                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1071                         $numUsers = count( $users );
1072
1073                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1074                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1075                         }
1076
1077                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1078                 }
1079
1080                 return ''; // nothing
1081         }
1082
1083         /**
1084          * Get a notice about how many intermediate edits and users there are
1085          *
1086          * @param int $numEdits
1087          * @param int $numUsers
1088          * @param int $limit
1089          *
1090          * @return string
1091          */
1092         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1093                 if ( $numUsers === 0 ) {
1094                         $msg = 'diff-multi-sameuser';
1095                 } elseif ( $numUsers > $limit ) {
1096                         $msg = 'diff-multi-manyusers';
1097                         $numUsers = $limit;
1098                 } else {
1099                         $msg = 'diff-multi-otherusers';
1100                 }
1101
1102                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1103         }
1104
1105         /**
1106          * Get a header for a specified revision.
1107          *
1108          * @param Revision $rev
1109          * @param string $complete 'complete' to get the header wrapped depending
1110          *        the visibility of the revision and a link to edit the page.
1111          *
1112          * @return string HTML fragment
1113          */
1114         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1115                 $lang = $this->getLanguage();
1116                 $user = $this->getUser();
1117                 $revtimestamp = $rev->getTimestamp();
1118                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1119                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1120                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1121
1122                 $header = $this->msg(
1123                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1124                         $timestamp,
1125                         $dateofrev,
1126                         $timeofrev
1127                 )->escaped();
1128
1129                 if ( $complete !== 'complete' ) {
1130                         return $header;
1131                 }
1132
1133                 $title = $rev->getTitle();
1134
1135                 $header = Linker::linkKnown( $title, $header, [],
1136                         [ 'oldid' => $rev->getId() ] );
1137
1138                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1139                         $editQuery = [ 'action' => 'edit' ];
1140                         if ( !$rev->isCurrent() ) {
1141                                 $editQuery['oldid'] = $rev->getId();
1142                         }
1143
1144                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1145                         $msg = $this->msg( $key )->escaped();
1146                         $editLink = $this->msg( 'parentheses' )->rawParams(
1147                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1148                         $header .= ' ' . Html::rawElement(
1149                                 'span',
1150                                 [ 'class' => 'mw-diff-edit' ],
1151                                 $editLink
1152                         );
1153                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1154                                 $header = Html::rawElement(
1155                                         'span',
1156                                         [ 'class' => 'history-deleted' ],
1157                                         $header
1158                                 );
1159                         }
1160                 } else {
1161                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1162                 }
1163
1164                 return $header;
1165         }
1166
1167         /**
1168          * Add the header to a diff body
1169          *
1170          * @param string $diff Diff body
1171          * @param string $otitle Old revision header
1172          * @param string $ntitle New revision header
1173          * @param string $multi Notice telling user that there are intermediate
1174          *   revisions between the ones being compared
1175          * @param string $notice Other notices, e.g. that user is viewing deleted content
1176          *
1177          * @return string
1178          */
1179         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1180                 // shared.css sets diff in interface language/dir, but the actual content
1181                 // is often in a different language, mostly the page content language/dir
1182                 $header = Html::openElement( 'table', [
1183                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1184                         'data-mw' => 'interface',
1185                 ] );
1186                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1187
1188                 if ( !$diff && !$otitle ) {
1189                         $header .= "
1190                         <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1191                         <td class=\"diff-ntitle\">{$ntitle}</td>
1192                         </tr>";
1193                         $multiColspan = 1;
1194                 } else {
1195                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1196                                 $header .= "
1197                                 <col class=\"diff-marker\" />
1198                                 <col class=\"diff-content\" />
1199                                 <col class=\"diff-marker\" />
1200                                 <col class=\"diff-content\" />";
1201                                 $colspan = 2;
1202                                 $multiColspan = 4;
1203                         } else {
1204                                 $colspan = 1;
1205                                 $multiColspan = 2;
1206                         }
1207                         if ( $otitle || $ntitle ) {
1208                                 $header .= "
1209                                 <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1210                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1211                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1212                                 </tr>";
1213                         }
1214                 }
1215
1216                 if ( $multi != '' ) {
1217                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1218                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1219                 }
1220                 if ( $notice != '' ) {
1221                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1222                                 "lang=\"{$userLang}\">{$notice}</td></tr>";
1223                 }
1224
1225                 return $header . $diff . "</table>";
1226         }
1227
1228         /**
1229          * Use specified text instead of loading from the database
1230          * @param Content $oldContent
1231          * @param Content $newContent
1232          * @since 1.21
1233          */
1234         public function setContent( Content $oldContent, Content $newContent ) {
1235                 $this->mOldContent = $oldContent;
1236                 $this->mNewContent = $newContent;
1237
1238                 $this->mTextLoaded = 2;
1239                 $this->mRevisionsLoaded = true;
1240         }
1241
1242         /**
1243          * Set the language in which the diff text is written
1244          * (Defaults to page content language).
1245          * @param Language|string $lang
1246          * @since 1.19
1247          */
1248         public function setTextLanguage( $lang ) {
1249                 $this->mDiffLang = wfGetLangObj( $lang );
1250         }
1251
1252         /**
1253          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1254          * to a pair of actual integers representing revision ids.
1255          *
1256          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1257          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1258          *
1259          * @return int[] List of two revision ids, older first, later second.
1260          *     Zero signifies invalid argument passed.
1261          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1262          */
1263         public function mapDiffPrevNext( $old, $new ) {
1264                 if ( $new === 'prev' ) {
1265                         // Show diff between revision $old and the previous one. Get previous one from DB.
1266                         $newid = intval( $old );
1267                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1268                 } elseif ( $new === 'next' ) {
1269                         // Show diff between revision $old and the next one. Get next one from DB.
1270                         $oldid = intval( $old );
1271                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1272                 } else {
1273                         $oldid = intval( $old );
1274                         $newid = intval( $new );
1275                 }
1276
1277                 return [ $oldid, $newid ];
1278         }
1279
1280         /**
1281          * Load revision IDs
1282          */
1283         private function loadRevisionIds() {
1284                 if ( $this->mRevisionsIdsLoaded ) {
1285                         return;
1286                 }
1287
1288                 $this->mRevisionsIdsLoaded = true;
1289
1290                 $old = $this->mOldid;
1291                 $new = $this->mNewid;
1292
1293                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1294                 if ( $new === 'next' && $this->mNewid === false ) {
1295                         # if no result, NewId points to the newest old revision. The only newer
1296                         # revision is cur, which is "0".
1297                         $this->mNewid = 0;
1298                 }
1299
1300                 Hooks::run(
1301                         'NewDifferenceEngine',
1302                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1303                 );
1304         }
1305
1306         /**
1307          * Load revision metadata for the specified articles. If newid is 0, then compare
1308          * the old article in oldid to the current article; if oldid is 0, then
1309          * compare the current article to the immediately previous one (ignoring the
1310          * value of newid).
1311          *
1312          * If oldid is false, leave the corresponding revision object set
1313          * to false. This is impossible via ordinary user input, and is provided for
1314          * API convenience.
1315          *
1316          * @return bool
1317          */
1318         public function loadRevisionData() {
1319                 if ( $this->mRevisionsLoaded ) {
1320                         return true;
1321                 }
1322
1323                 // Whether it succeeds or fails, we don't want to try again
1324                 $this->mRevisionsLoaded = true;
1325
1326                 $this->loadRevisionIds();
1327
1328                 // Load the new revision object
1329                 if ( $this->mNewid ) {
1330                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1331                 } else {
1332                         $this->mNewRev = Revision::newFromTitle(
1333                                 $this->getTitle(),
1334                                 false,
1335                                 Revision::READ_NORMAL
1336                         );
1337                 }
1338
1339                 if ( !$this->mNewRev instanceof Revision ) {
1340                         return false;
1341                 }
1342
1343                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1344                 $this->mNewid = $this->mNewRev->getId();
1345                 $this->mNewPage = $this->mNewRev->getTitle();
1346
1347                 // Load the old revision object
1348                 $this->mOldRev = false;
1349                 if ( $this->mOldid ) {
1350                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1351                 } elseif ( $this->mOldid === 0 ) {
1352                         $rev = $this->mNewRev->getPrevious();
1353                         if ( $rev ) {
1354                                 $this->mOldid = $rev->getId();
1355                                 $this->mOldRev = $rev;
1356                         } else {
1357                                 // No previous revision; mark to show as first-version only.
1358                                 $this->mOldid = false;
1359                                 $this->mOldRev = false;
1360                         }
1361                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1362
1363                 if ( is_null( $this->mOldRev ) ) {
1364                         return false;
1365                 }
1366
1367                 if ( $this->mOldRev ) {
1368                         $this->mOldPage = $this->mOldRev->getTitle();
1369                 }
1370
1371                 // Load tags information for both revisions
1372                 $dbr = wfGetDB( DB_REPLICA );
1373                 if ( $this->mOldid !== false ) {
1374                         $this->mOldTags = $dbr->selectField(
1375                                 'tag_summary',
1376                                 'ts_tags',
1377                                 [ 'ts_rev_id' => $this->mOldid ],
1378                                 __METHOD__
1379                         );
1380                 } else {
1381                         $this->mOldTags = false;
1382                 }
1383                 $this->mNewTags = $dbr->selectField(
1384                         'tag_summary',
1385                         'ts_tags',
1386                         [ 'ts_rev_id' => $this->mNewid ],
1387                         __METHOD__
1388                 );
1389
1390                 return true;
1391         }
1392
1393         /**
1394          * Load the text of the revisions, as well as revision data.
1395          *
1396          * @return bool
1397          */
1398         public function loadText() {
1399                 if ( $this->mTextLoaded == 2 ) {
1400                         return true;
1401                 }
1402
1403                 // Whether it succeeds or fails, we don't want to try again
1404                 $this->mTextLoaded = 2;
1405
1406                 if ( !$this->loadRevisionData() ) {
1407                         return false;
1408                 }
1409
1410                 if ( $this->mOldRev ) {
1411                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1412                         if ( $this->mOldContent === null ) {
1413                                 return false;
1414                         }
1415                 }
1416
1417                 if ( $this->mNewRev ) {
1418                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1419                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1420                         if ( $this->mNewContent === null ) {
1421                                 return false;
1422                         }
1423                 }
1424
1425                 return true;
1426         }
1427
1428         /**
1429          * Load the text of the new revision, not the old one
1430          *
1431          * @return bool
1432          */
1433         public function loadNewText() {
1434                 if ( $this->mTextLoaded >= 1 ) {
1435                         return true;
1436                 }
1437
1438                 $this->mTextLoaded = 1;
1439
1440                 if ( !$this->loadRevisionData() ) {
1441                         return false;
1442                 }
1443
1444                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1445
1446                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1447
1448                 return true;
1449         }
1450
1451 }