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                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 609                         $this->loadNewText();
 610                         $out->setRevisionId( $this->mNewid );
 611                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 612                         $out->setArticleFlag( true );
 613
 614                         if ( !Hooks::run( 'ArticleContentViewCustom',
 615                                 [ $this->mNewContent, $this->mNewPage, $out ] )
 616                         ) {
 617                                 // Handled by extension
 618                         } else {
 619                                 // Normal page
 620                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 621                                         // If the Title stored in the context is the same as the one
 622                                         // of the new revision, we can use its associated WikiPage
 623                                         // object.
 624                                         $wikiPage = $this->getWikiPage();
 625                                 } else {
 626                                         // Otherwise we need to create our own WikiPage object
 627                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 628                                 }
 629
 630                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 631
 632                                 # WikiPage::getParserOutput() should not return false, but just in case
 633                                 if ( $parserOutput ) {
 634                                         // Allow extensions to change parser output here
 635                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput',
 636                                                 [ $this, $out, $parserOutput, $wikiPage ] )
 637                                         ) {
 638                                                 $out->addParserOutput( $parserOutput );
 639                                         }
 640                                 }
 641                         }
 642                 }
 643
 644                 // Allow extensions to optionally not show the final patrolled link
 645                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 646                         # Add redundant patrol link on bottom...
 647                         $out->addHTML( $this->markPatrolledLink() );
 648                 }
 649         }
 650
 651         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 652                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 653
 654                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 655                         $parserOptions->setEditSection( false );
 656                 }
 657
 658                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 659
 660                 return $parserOutput;
 661         }
 662
 663         /**
 664          * Get the diff text, send it to the OutputPage object
 665          * Returns false if the diff could not be generated, otherwise returns true
 666          *
 667          * @param string|bool $otitle Header for old text or false
 668          * @param string|bool $ntitle Header for new text or false
 669          * @param string $notice HTML between diff header and body
 670          *
 671          * @return bool
 672          */
 673         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 674                 // Allow extensions to affect the output here
 675                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 676
 677                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 678                 if ( $diff === false ) {
 679                         $this->showMissingRevision();
 680
 681                         return false;
 682                 } else {
 683                         $this->showDiffStyle();
 684                         $this->getOutput()->addHTML( $diff );
 685
 686                         return true;
 687                 }
 688         }
 689
 690         /**
 691          * Add style sheets for diff display.
 692          */
 693         public function showDiffStyle() {
 694                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 695         }
 696
 697         /**
 698          * Get complete diff table, including header
 699          *
 700          * @param string|bool $otitle Header for old text or false
 701          * @param string|bool $ntitle Header for new text or false
 702          * @param string $notice HTML between diff header and body
 703          *
 704          * @return mixed
 705          */
 706         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 707                 $body = $this->getDiffBody();
 708                 if ( $body === false ) {
 709                         return false;
 710                 }
 711
 712                 $multi = $this->getMultiNotice();
 713                 // Display a message when the diff is empty
 714                 if ( $body === '' ) {
 715                         $notice .= '<div class="mw-diff-empty">' .
 716                                 $this->msg( 'diff-empty' )->parse() .
 717                                 "</div>\n";
 718                 }
 719
 720                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 721         }
 722
 723         /**
 724          * Get the diff table body, without header
 725          *
 726          * @return mixed (string/false)
 727          */
 728         public function getDiffBody() {
 729                 $this->mCacheHit = true;
 730                 // Check if the diff should be hidden from this user
 731                 if ( !$this->loadRevisionData() ) {
 732                         return false;
 733                 } elseif ( $this->mOldRev &&
 734                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 735                 ) {
 736                         return false;
 737                 } elseif ( $this->mNewRev &&
 738                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 739                 ) {
 740                         return false;
 741                 }
 742                 // Short-circuit
 743                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 744                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 745                 ) {
 746                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 747                                 return '';
 748                         }
 749                 }
 750                 // Cacheable?
 751                 $key = false;
 752                 $cache = ObjectCache::getMainWANInstance();
 753                 if ( $this->mOldid && $this->mNewid ) {
 754                         $key = $this->getDiffBodyCacheKey();
 755
 756                         // Try cache
 757                         if ( !$this->mRefreshCache ) {
 758                                 $difftext = $cache->get( $key );
 759                                 if ( $difftext ) {
 760                                         wfIncrStats( 'diff_cache.hit' );
 761                                         $difftext = $this->localiseLineNumbers( $difftext );
 762                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 763
 764                                         return $difftext;
 765                                 }
 766                         } // don't try to load but save the result
 767                 }
 768                 $this->mCacheHit = false;
 769
 770                 // Loadtext is permission safe, this just clears out the diff
 771                 if ( !$this->loadText() ) {
 772                         return false;
 773                 }
 774
 775                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 776
 777                 // Avoid PHP 7.1 warning from passing $this by reference
 778                 $diffEngine = $this;
 779
 780                 // Save to cache for 7 days
 781                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 782                         wfIncrStats( 'diff_cache.uncacheable' );
 783                 } elseif ( $key !== false && $difftext !== false ) {
 784                         wfIncrStats( 'diff_cache.miss' );
 785                         $cache->set( $key, $difftext, 7 * 86400 );
 786                 } else {
 787                         wfIncrStats( 'diff_cache.uncacheable' );
 788                 }
 789                 // Replace line numbers with the text in the user's language
 790                 if ( $difftext !== false ) {
 791                         $difftext = $this->localiseLineNumbers( $difftext );
 792                 }
 793
 794                 return $difftext;
 795         }
 796
 797         /**
 798          * Returns the cache key for diff body text or content.
 799          *
 800          * @since 1.23
 801          *
 802          * @throws MWException
 803          * @return string
 804          */
 805         protected function getDiffBodyCacheKey() {
 806                 if ( !$this->mOldid || !$this->mNewid ) {
 807                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 808                 }
 809
 810                 return wfMemcKey( 'diff', 'version', self::DIFF_VERSION,
 811                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 812         }
 813
 814         /**
 815          * Generate a diff, no caching.
 816          *
 817          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 818          * serialization of the given Content objects. This will fail if $old or $new are not
 819          * instances of TextContent.
 820          *
 821          * Subclasses may override this to provide a different rendering for the diff,
 822          * perhaps taking advantage of the content's native form. This is required for all content
 823          * models that are not text based.
 824          *
 825          * @since 1.21
 826          *
 827          * @param Content $old Old content
 828          * @param Content $new New content
 829          *
 830          * @throws MWException If old or new content is not an instance of TextContent.
 831          * @return bool|string
 832          */
 833         public function generateContentDiffBody( Content $old, Content $new ) {
 834                 if ( !( $old instanceof TextContent ) ) {
 835                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 836                                 "override generateContentDiffBody to fix this." );
 837                 }
 838
 839                 if ( !( $new instanceof TextContent ) ) {
 840                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 841                                 . "override generateContentDiffBody to fix this." );
 842                 }
 843
 844                 $otext = $old->serialize();
 845                 $ntext = $new->serialize();
 846
 847                 return $this->generateTextDiffBody( $otext, $ntext );
 848         }
 849
 850         /**
 851          * Generate a diff, no caching
 852          *
 853          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 854          *
 855          * @param string $otext Old text, must be already segmented
 856          * @param string $ntext New text, must be already segmented
 857          *
 858          * @return bool|string
 859          */
 860         public function generateTextDiffBody( $otext, $ntext ) {
 861                 $diff = function () use ( $otext, $ntext ) {
 862                         $time = microtime( true );
 863
 864                         $result = $this->textDiff( $otext, $ntext );
 865
 866                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 867                         MediaWikiServices::getInstance()->getStatsdDataFactory()->timing( 'diff_time', $time );
 868                         // Log requests slower than 99th percentile
 869                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 870                                 wfDebugLog( 'diff',
 871                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 872                         }
 873
 874                         return $result;
 875                 };
 876
 877                 /**
 878                  * @param Status $status
 879                  * @throws FatalError
 880                  */
 881                 $error = function ( $status ) {
 882                         throw new FatalError( $status->getWikiText() );
 883                 };
 884
 885                 // Use PoolCounter if the diff looks like it can be expensive
 886                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 887                         $work = new PoolCounterWorkViaCallback( 'diff',
 888                                 md5( $otext ) . md5( $ntext ),
 889                                 [ 'doWork' => $diff, 'error' => $error ]
 890                         );
 891                         return $work->execute();
 892                 }
 893
 894                 return $diff();
 895         }
 896
 897         /**
 898          * Generates diff, to be wrapped internally in a logging/instrumentation
 899          *
 900          * @param string $otext Old text, must be already segmented
 901          * @param string $ntext New text, must be already segmented
 902          * @return bool|string
 903          */
 904         protected function textDiff( $otext, $ntext ) {
 905                 global $wgExternalDiffEngine, $wgContLang;
 906
 907                 $otext = str_replace( "\r\n", "\n", $otext );
 908                 $ntext = str_replace( "\r\n", "\n", $ntext );
 909
 910                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 911                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 912                         $wgExternalDiffEngine = false;
 913                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 914                         // Same as above, but with no deprecation warnings
 915                         $wgExternalDiffEngine = false;
 916                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 917                         // And prevent people from shooting themselves in the foot...
 918                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 919                         $wgExternalDiffEngine = false;
 920                 }
 921
 922                 // Better external diff engine, the 2 may some day be dropped
 923                 // This one does the escaping and segmenting itself
 924                 if ( function_exists( 'wikidiff2_do_diff' ) && $wgExternalDiffEngine === false ) {
 925                         $wikidiff2Version = phpversion( 'wikidiff2' );
 926                         if (
 927                                 $wikidiff2Version !== false &&
 928                                 version_compare( $wikidiff2Version, '0.3', '>=' )
 929                         ) {
 930                                 $text = wikidiff2_do_diff(
 931                                         $otext,
 932                                         $ntext,
 933                                         2,
 934                                         $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' )
 935                                 );
 936                         } else {
 937                                 // Don't pass the 4th parameter for compatibility with older versions of wikidiff2
 938                                 $text = wikidiff2_do_diff(
 939                                         $otext,
 940                                         $ntext,
 941                                         2
 942                                 );
 943
 944                                 // Log a warning in case the configuration value is set to not silently ignore it
 945                                 if ( $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' ) > 0 ) {
 946                                         wfLogWarning( '$wgWikiDiff2MovedParagraphDetectionCutoff is set but has no
 947                                                 effect since the used version of WikiDiff2 does not support it.' );
 948                                 }
 949                         }
 950
 951                         $text .= $this->debug( 'wikidiff2' );
 952
 953                         return $text;
 954                 } elseif ( $wgExternalDiffEngine !== false && is_executable( $wgExternalDiffEngine ) ) {
 955                         # Diff via the shell
 956                         $tmpDir = wfTempDir();
 957                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 958                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 959
 960                         $tempFile1 = fopen( $tempName1, "w" );
 961                         if ( !$tempFile1 ) {
 962                                 return false;
 963                         }
 964                         $tempFile2 = fopen( $tempName2, "w" );
 965                         if ( !$tempFile2 ) {
 966                                 return false;
 967                         }
 968                         fwrite( $tempFile1, $otext );
 969                         fwrite( $tempFile2, $ntext );
 970                         fclose( $tempFile1 );
 971                         fclose( $tempFile2 );
 972                         $cmd = [ $wgExternalDiffEngine, $tempName1, $tempName2 ];
 973                         $result = Shell::command( $cmd )
 974                                 ->execute();
 975                         $exitCode = $result->getExitCode();
 976                         if ( $exitCode !== 0 ) {
 977                                 throw new Exception( "External diff command returned code {$exitCode}. Stderr: "
 978                                         . wfEscapeWikiText( $result->getStderr() )
 979                                 );
 980                         }
 981                         $difftext = $result->getStdout();
 982                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 983                         unlink( $tempName1 );
 984                         unlink( $tempName2 );
 985
 986                         return $difftext;
 987                 }
 988
 989                 # Native PHP diff
 990                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 991                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 992                 $diffs = new Diff( $ota, $nta );
 993                 $formatter = new TableDiffFormatter();
 994                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 995
 996                 return $difftext;
 997         }
 998
 999         /**
1000          * Generate a debug comment indicating diff generating time,
1001          * server node, and generator backend.
1002          *
1003          * @param string $generator : What diff engine was used
1004          *
1005          * @return string
1006          */
1007         protected function debug( $generator = "internal" ) {
1008                 global $wgShowHostnames;
1009                 if ( !$this->enableDebugComment ) {
1010                         return '';
1011                 }
1012                 $data = [ $generator ];
1013                 if ( $wgShowHostnames ) {
1014                         $data[] = wfHostname();
1015                 }
1016                 $data[] = wfTimestamp( TS_DB );
1017
1018                 return "<!-- diff generator: " .
1019                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1020                         " -->\n";
1021         }
1022
1023         /**
1024          * Replace line numbers with the text in the user's language
1025          *
1026          * @param string $text
1027          *
1028          * @return mixed
1029          */
1030         public function localiseLineNumbers( $text ) {
1031                 return preg_replace_callback(
1032                         '/<!--LINE (\d+)-->/',
1033                         [ $this, 'localiseLineNumbersCb' ],
1034                         $text
1035                 );
1036         }
1037
1038         public function localiseLineNumbersCb( $matches ) {
1039                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1040                         return '';
1041                 }
1042
1043                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1044         }
1045
1046         /**
1047          * If there are revisions between the ones being compared, return a note saying so.
1048          *
1049          * @return string
1050          */
1051         public function getMultiNotice() {
1052                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1053                         return '';
1054                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1055                         // Comparing two different pages? Count would be meaningless.
1056                         return '';
1057                 }
1058
1059                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1060                         $oldRev = $this->mNewRev; // flip
1061                         $newRev = $this->mOldRev; // flip
1062                 } else { // normal case
1063                         $oldRev = $this->mOldRev;
1064                         $newRev = $this->mNewRev;
1065                 }
1066
1067                 // Sanity: don't show the notice if too many rows must be scanned
1068                 // @todo show some special message for that case
1069                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1070                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1071                         $limit = 100; // use diff-multi-manyusers if too many users
1072                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1073                         $numUsers = count( $users );
1074
1075                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1076                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1077                         }
1078
1079                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1080                 }
1081
1082                 return ''; // nothing
1083         }
1084
1085         /**
1086          * Get a notice about how many intermediate edits and users there are
1087          *
1088          * @param int $numEdits
1089          * @param int $numUsers
1090          * @param int $limit
1091          *
1092          * @return string
1093          */
1094         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1095                 if ( $numUsers === 0 ) {
1096                         $msg = 'diff-multi-sameuser';
1097                 } elseif ( $numUsers > $limit ) {
1098                         $msg = 'diff-multi-manyusers';
1099                         $numUsers = $limit;
1100                 } else {
1101                         $msg = 'diff-multi-otherusers';
1102                 }
1103
1104                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1105         }
1106
1107         /**
1108          * Get a header for a specified revision.
1109          *
1110          * @param Revision $rev
1111          * @param string $complete 'complete' to get the header wrapped depending
1112          *        the visibility of the revision and a link to edit the page.
1113          *
1114          * @return string HTML fragment
1115          */
1116         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1117                 $lang = $this->getLanguage();
1118                 $user = $this->getUser();
1119                 $revtimestamp = $rev->getTimestamp();
1120                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1121                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1122                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1123
1124                 $header = $this->msg(
1125                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1126                         $timestamp,
1127                         $dateofrev,
1128                         $timeofrev
1129                 )->escaped();
1130
1131                 if ( $complete !== 'complete' ) {
1132                         return $header;
1133                 }
1134
1135                 $title = $rev->getTitle();
1136
1137                 $header = Linker::linkKnown( $title, $header, [],
1138                         [ 'oldid' => $rev->getId() ] );
1139
1140                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1141                         $editQuery = [ 'action' => 'edit' ];
1142                         if ( !$rev->isCurrent() ) {
1143                                 $editQuery['oldid'] = $rev->getId();
1144                         }
1145
1146                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1147                         $msg = $this->msg( $key )->escaped();
1148                         $editLink = $this->msg( 'parentheses' )->rawParams(
1149                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1150                         $header .= ' ' . Html::rawElement(
1151                                 'span',
1152                                 [ 'class' => 'mw-diff-edit' ],
1153                                 $editLink
1154                         );
1155                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1156                                 $header = Html::rawElement(
1157                                         'span',
1158                                         [ 'class' => 'history-deleted' ],
1159                                         $header
1160                                 );
1161                         }
1162                 } else {
1163                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1164                 }
1165
1166                 return $header;
1167         }
1168
1169         /**
1170          * Add the header to a diff body
1171          *
1172          * @param string $diff Diff body
1173          * @param string $otitle Old revision header
1174          * @param string $ntitle New revision header
1175          * @param string $multi Notice telling user that there are intermediate
1176          *   revisions between the ones being compared
1177          * @param string $notice Other notices, e.g. that user is viewing deleted content
1178          *
1179          * @return string
1180          */
1181         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1182                 // shared.css sets diff in interface language/dir, but the actual content
1183                 // is often in a different language, mostly the page content language/dir
1184                 $header = Html::openElement( 'table', [
1185                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1186                         'data-mw' => 'interface',
1187                 ] );
1188                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1189
1190                 if ( !$diff && !$otitle ) {
1191                         $header .= "
1192                         <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1193                         <td class=\"diff-ntitle\">{$ntitle}</td>
1194                         </tr>";
1195                         $multiColspan = 1;
1196                 } else {
1197                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1198                                 $header .= "
1199                                 <col class=\"diff-marker\" />
1200                                 <col class=\"diff-content\" />
1201                                 <col class=\"diff-marker\" />
1202                                 <col class=\"diff-content\" />";
1203                                 $colspan = 2;
1204                                 $multiColspan = 4;
1205                         } else {
1206                                 $colspan = 1;
1207                                 $multiColspan = 2;
1208                         }
1209                         if ( $otitle || $ntitle ) {
1210                                 $header .= "
1211                                 <tr style=\"vertical-align: top;\" lang=\"{$userLang}\">
1212                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1213                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1214                                 </tr>";
1215                         }
1216                 }
1217
1218                 if ( $multi != '' ) {
1219                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1220                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1221                 }
1222                 if ( $notice != '' ) {
1223                         $header .= "<tr><td colspan=\"{$multiColspan}\" style=\"text-align: center;\" " .
1224                                 "lang=\"{$userLang}\">{$notice}</td></tr>";
1225                 }
1226
1227                 return $header . $diff . "</table>";
1228         }
1229
1230         /**
1231          * Use specified text instead of loading from the database
1232          * @param Content $oldContent
1233          * @param Content $newContent
1234          * @since 1.21
1235          */
1236         public function setContent( Content $oldContent, Content $newContent ) {
1237                 $this->mOldContent = $oldContent;
1238                 $this->mNewContent = $newContent;
1239
1240                 $this->mTextLoaded = 2;
1241                 $this->mRevisionsLoaded = true;
1242         }
1243
1244         /**
1245          * Set the language in which the diff text is written
1246          * (Defaults to page content language).
1247          * @param Language|string $lang
1248          * @since 1.19
1249          */
1250         public function setTextLanguage( $lang ) {
1251                 $this->mDiffLang = wfGetLangObj( $lang );
1252         }
1253
1254         /**
1255          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1256          * to a pair of actual integers representing revision ids.
1257          *
1258          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1259          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1260          *
1261          * @return int[] List of two revision ids, older first, later second.
1262          *     Zero signifies invalid argument passed.
1263          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1264          */
1265         public function mapDiffPrevNext( $old, $new ) {
1266                 if ( $new === 'prev' ) {
1267                         // Show diff between revision $old and the previous one. Get previous one from DB.
1268                         $newid = intval( $old );
1269                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1270                 } elseif ( $new === 'next' ) {
1271                         // Show diff between revision $old and the next one. Get next one from DB.
1272                         $oldid = intval( $old );
1273                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1274                 } else {
1275                         $oldid = intval( $old );
1276                         $newid = intval( $new );
1277                 }
1278
1279                 return [ $oldid, $newid ];
1280         }
1281
1282         /**
1283          * Load revision IDs
1284          */
1285         private function loadRevisionIds() {
1286                 if ( $this->mRevisionsIdsLoaded ) {
1287                         return;
1288                 }
1289
1290                 $this->mRevisionsIdsLoaded = true;
1291
1292                 $old = $this->mOldid;
1293                 $new = $this->mNewid;
1294
1295                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1296                 if ( $new === 'next' && $this->mNewid === false ) {
1297                         # if no result, NewId points to the newest old revision. The only newer
1298                         # revision is cur, which is "0".
1299                         $this->mNewid = 0;
1300                 }
1301
1302                 Hooks::run(
1303                         'NewDifferenceEngine',
1304                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1305                 );
1306         }
1307
1308         /**
1309          * Load revision metadata for the specified articles. If newid is 0, then compare
1310          * the old article in oldid to the current article; if oldid is 0, then
1311          * compare the current article to the immediately previous one (ignoring the
1312          * value of newid).
1313          *
1314          * If oldid is false, leave the corresponding revision object set
1315          * to false. This is impossible via ordinary user input, and is provided for
1316          * API convenience.
1317          *
1318          * @return bool
1319          */
1320         public function loadRevisionData() {
1321                 if ( $this->mRevisionsLoaded ) {
1322                         return true;
1323                 }
1324
1325                 // Whether it succeeds or fails, we don't want to try again
1326                 $this->mRevisionsLoaded = true;
1327
1328                 $this->loadRevisionIds();
1329
1330                 // Load the new revision object
1331                 if ( $this->mNewid ) {
1332                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1333                 } else {
1334                         $this->mNewRev = Revision::newFromTitle(
1335                                 $this->getTitle(),
1336                                 false,
1337                                 Revision::READ_NORMAL
1338                         );
1339                 }
1340
1341                 if ( !$this->mNewRev instanceof Revision ) {
1342                         return false;
1343                 }
1344
1345                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1346                 $this->mNewid = $this->mNewRev->getId();
1347                 $this->mNewPage = $this->mNewRev->getTitle();
1348
1349                 // Load the old revision object
1350                 $this->mOldRev = false;
1351                 if ( $this->mOldid ) {
1352                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1353                 } elseif ( $this->mOldid === 0 ) {
1354                         $rev = $this->mNewRev->getPrevious();
1355                         if ( $rev ) {
1356                                 $this->mOldid = $rev->getId();
1357                                 $this->mOldRev = $rev;
1358                         } else {
1359                                 // No previous revision; mark to show as first-version only.
1360                                 $this->mOldid = false;
1361                                 $this->mOldRev = false;
1362                         }
1363                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1364
1365                 if ( is_null( $this->mOldRev ) ) {
1366                         return false;
1367                 }
1368
1369                 if ( $this->mOldRev ) {
1370                         $this->mOldPage = $this->mOldRev->getTitle();
1371                 }
1372
1373                 // Load tags information for both revisions
1374                 $dbr = wfGetDB( DB_REPLICA );
1375                 if ( $this->mOldid !== false ) {
1376                         $this->mOldTags = $dbr->selectField(
1377                                 'tag_summary',
1378                                 'ts_tags',
1379                                 [ 'ts_rev_id' => $this->mOldid ],
1380                                 __METHOD__
1381                         );
1382                 } else {
1383                         $this->mOldTags = false;
1384                 }
1385                 $this->mNewTags = $dbr->selectField(
1386                         'tag_summary',
1387                         'ts_tags',
1388                         [ 'ts_rev_id' => $this->mNewid ],
1389                         __METHOD__
1390                 );
1391
1392                 return true;
1393         }
1394
1395         /**
1396          * Load the text of the revisions, as well as revision data.
1397          *
1398          * @return bool
1399          */
1400         public function loadText() {
1401                 if ( $this->mTextLoaded == 2 ) {
1402                         return true;
1403                 }
1404
1405                 // Whether it succeeds or fails, we don't want to try again
1406                 $this->mTextLoaded = 2;
1407
1408                 if ( !$this->loadRevisionData() ) {
1409                         return false;
1410                 }
1411
1412                 if ( $this->mOldRev ) {
1413                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1414                         if ( $this->mOldContent === null ) {
1415                                 return false;
1416                         }
1417                 }
1418
1419                 if ( $this->mNewRev ) {
1420                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1421                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1422                         if ( $this->mNewContent === null ) {
1423                                 return false;
1424                         }
1425                 }
1426
1427                 return true;
1428         }
1429
1430         /**
1431          * Load the text of the new revision, not the old one
1432          *
1433          * @return bool
1434          */
1435         public function loadNewText() {
1436                 if ( $this->mTextLoaded >= 1 ) {
1437                         return true;
1438                 }
1439
1440                 $this->mTextLoaded = 1;
1441
1442                 if ( !$this->loadRevisionData() ) {
1443                         return false;
1444                 }
1445
1446                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1447
1448                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1449
1450                 return true;
1451         }
1452
1453 }