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
  24 /** @deprecated use class constant instead */
  25 define( 'MW_DIFF_VERSION', '1.11a' );
  26
  27 /**
  28  * @todo document
  29  * @ingroup DifferenceEngine
  30  */
  31 class DifferenceEngine extends ContextSource {
  32         /**
  33          * Constant to indicate diff cache compatibility.
  34          * Bump this when changing the diff formatting in a way that
  35          * fixes important bugs or such to force cached diff views to
  36          * clear.
  37          */
  38         const DIFF_VERSION = MW_DIFF_VERSION;
  39
  40         /** @var int */
  41         public $mOldid;
  42
  43         /** @var int */
  44         public $mNewid;
  45
  46         private $mOldTags;
  47         private $mNewTags;
  48
  49         /** @var Content */
  50         public $mOldContent;
  51
  52         /** @var Content */
  53         public $mNewContent;
  54
  55         /** @var Language */
  56         protected $mDiffLang;
  57
  58         /** @var Title */
  59         public $mOldPage;
  60
  61         /** @var Title */
  62         public $mNewPage;
  63
  64         /** @var Revision */
  65         public $mOldRev;
  66
  67         /** @var Revision */
  68         public $mNewRev;
  69
  70         /** @var bool Have the revisions IDs been loaded */
  71         private $mRevisionsIdsLoaded = false;
  72
  73         /** @var bool Have the revisions been loaded */
  74         public $mRevisionsLoaded = false;
  75
  76         /** @var int How many text blobs have been loaded, 0, 1 or 2? */
  77         public $mTextLoaded = 0;
  78
  79         /** @var bool Was the diff fetched from cache? */
  80         public $mCacheHit = false;
  81
  82         /**
  83          * Set this to true to add debug info to the HTML output.
  84          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  85          * (T22601)
  86          */
  87         public $enableDebugComment = false;
  88
  89         /** @var bool If true, line X is not displayed when X is 1, for example
  90          *    to increase readability and conserve space with many small diffs.
  91          */
  92         protected $mReducedLineNumbers = false;
  93
  94         /** @var string Link to action=markpatrolled */
  95         protected $mMarkPatrolledLink = null;
  96
  97         /** @var bool Show rev_deleted content if allowed */
  98         protected $unhide = false;
  99
 100         /** @var bool Refresh the diff cache */
 101         protected $mRefreshCache = false;
 102
 103         /**#@-*/
 104
 105         /**
 106          * Constructor
 107          * @param IContextSource $context Context to use, anything else will be ignored
 108          * @param int $old Old ID we want to show and diff with.
 109          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 110          * @param int $rcid Deprecated, no longer used!
 111          * @param bool $refreshCache If set, refreshes the diff cache
 112          * @param bool $unhide If set, allow viewing deleted revs
 113          */
 114         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 115                 $refreshCache = false, $unhide = false
 116         ) {
 117                 if ( $context instanceof IContextSource ) {
 118                         $this->setContext( $context );
 119                 }
 120
 121                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 122
 123                 $this->mOldid = $old;
 124                 $this->mNewid = $new;
 125                 $this->mRefreshCache = $refreshCache;
 126                 $this->unhide = $unhide;
 127         }
 128
 129         /**
 130          * @param bool $value
 131          */
 132         public function setReducedLineNumbers( $value = true ) {
 133                 $this->mReducedLineNumbers = $value;
 134         }
 135
 136         /**
 137          * @return Language
 138          */
 139         public function getDiffLang() {
 140                 if ( $this->mDiffLang === null ) {
 141                         # Default language in which the diff text is written.
 142                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 143                 }
 144
 145                 return $this->mDiffLang;
 146         }
 147
 148         /**
 149          * @return bool
 150          */
 151         public function wasCacheHit() {
 152                 return $this->mCacheHit;
 153         }
 154
 155         /**
 156          * @return int
 157          */
 158         public function getOldid() {
 159                 $this->loadRevisionIds();
 160
 161                 return $this->mOldid;
 162         }
 163
 164         /**
 165          * @return bool|int
 166          */
 167         public function getNewid() {
 168                 $this->loadRevisionIds();
 169
 170                 return $this->mNewid;
 171         }
 172
 173         /**
 174          * Look up a special:Undelete link to the given deleted revision id,
 175          * as a workaround for being unable to load deleted diffs in currently.
 176          *
 177          * @param int $id Revision ID
 178          *
 179          * @return string|bool Link HTML or false
 180          */
 181         public function deletedLink( $id ) {
 182                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 183                         $dbr = wfGetDB( DB_REPLICA );
 184                         $row = $dbr->selectRow( 'archive', '*',
 185                                 [ 'ar_rev_id' => $id ],
 186                                 __METHOD__ );
 187                         if ( $row ) {
 188                                 $rev = Revision::newFromArchiveRow( $row );
 189                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 190
 191                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
 192                                         'target' => $title->getPrefixedText(),
 193                                         'timestamp' => $rev->getTimestamp()
 194                                 ] );
 195                         }
 196                 }
 197
 198                 return false;
 199         }
 200
 201         /**
 202          * Build a wikitext link toward a deleted revision, if viewable.
 203          *
 204          * @param int $id Revision ID
 205          *
 206          * @return string Wikitext fragment
 207          */
 208         public function deletedIdMarker( $id ) {
 209                 $link = $this->deletedLink( $id );
 210                 if ( $link ) {
 211                         return "[$link $id]";
 212                 } else {
 213                         return (string)$id;
 214                 }
 215         }
 216
 217         private function showMissingRevision() {
 218                 $out = $this->getOutput();
 219
 220                 $missing = [];
 221                 if ( $this->mOldRev === null ||
 222                         ( $this->mOldRev && $this->mOldContent === null )
 223                 ) {
 224                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 225                 }
 226                 if ( $this->mNewRev === null ||
 227                         ( $this->mNewRev && $this->mNewContent === null )
 228                 ) {
 229                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 230                 }
 231
 232                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 233                 $msg = $this->msg( 'difference-missing-revision' )
 234                         ->params( $this->getLanguage()->listToText( $missing ) )
 235                         ->numParams( count( $missing ) )
 236                         ->parseAsBlock();
 237                 $out->addHTML( $msg );
 238         }
 239
 240         public function showDiffPage( $diffOnly = false ) {
 241                 # Allow frames except in certain special cases
 242                 $out = $this->getOutput();
 243                 $out->allowClickjacking();
 244                 $out->setRobotPolicy( 'noindex,nofollow' );
 245
 246                 // Allow extensions to add any extra output here
 247                 Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
 248
 249                 if ( !$this->loadRevisionData() ) {
 250                         if ( Hooks::run( 'DifferenceEngineShowDiffPageMaybeShowMissingRevision', [ $this ] ) ) {
 251                                 $this->showMissingRevision();
 252                         }
 253                         return;
 254                 }
 255
 256                 $user = $this->getUser();
 257                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 258                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 259                         $permErrors = wfMergeErrorArrays( $permErrors,
 260                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 261                 }
 262                 if ( count( $permErrors ) ) {
 263                         throw new PermissionsError( 'read', $permErrors );
 264                 }
 265
 266                 $rollback = '';
 267
 268                 $query = [];
 269                 # Carry over 'diffonly' param via navigation links
 270                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 271                         $query['diffonly'] = $diffOnly;
 272                 }
 273                 # Cascade unhide param in links for easy deletion browsing
 274                 if ( $this->unhide ) {
 275                         $query['unhide'] = 1;
 276                 }
 277
 278                 # Check if one of the revisions is deleted/suppressed
 279                 $deleted = $suppressed = false;
 280                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 281
 282                 $revisionTools = [];
 283
 284                 # mOldRev is false if the difference engine is called with a "vague" query for
 285                 # a diff between a version V and its previous version V' AND the version V
 286                 # is the first version of that article. In that case, V' does not exist.
 287                 if ( $this->mOldRev === false ) {
 288                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 289                         $samePage = true;
 290                         $oldHeader = '';
 291                         // Allow extensions to change the $oldHeader variable
 292                         Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
 293                 } else {
 294                         Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 295
 296                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 297                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 298                                 $samePage = true;
 299                         } else {
 300                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 301                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 302                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 303                                 $samePage = false;
 304                         }
 305
 306                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 307                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 308                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 309                                         if ( $rollbackLink ) {
 310                                                 $out->preventClickjacking();
 311                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 312                                         }
 313                                 }
 314
 315                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 316                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 317                                 ) {
 318                                         $undoLink = Html::element( 'a', [
 319                                                         'href' => $this->mNewPage->getLocalURL( [
 320                                                                 'action' => 'edit',
 321                                                                 'undoafter' => $this->mOldid,
 322                                                                 'undo' => $this->mNewid
 323                                                         ] ),
 324                                                         'title' => Linker::titleAttrib( 'undo' ),
 325                                                 ],
 326                                                 $this->msg( 'editundo' )->text()
 327                                         );
 328                                         $revisionTools['mw-diff-undo'] = $undoLink;
 329                                 }
 330                         }
 331
 332                         # Make "previous revision link"
 333                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 334                                 $prevlink = Linker::linkKnown(
 335                                         $this->mOldPage,
 336                                         $this->msg( 'previousdiff' )->escaped(),
 337                                         [ 'id' => 'differences-prevlink' ],
 338                                         [ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
 339                                 );
 340                         } else {
 341                                 $prevlink = '&#160;';
 342                         }
 343
 344                         if ( $this->mOldRev->isMinor() ) {
 345                                 $oldminor = ChangesList::flag( 'minor' );
 346                         } else {
 347                                 $oldminor = '';
 348                         }
 349
 350                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 351                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 352                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );
 353
 354                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 355                                 '<div id="mw-diff-otitle2">' .
 356                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 357                                 '<div id="mw-diff-otitle3">' . $oldminor .
 358                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 359                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 360                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 361
 362                         // Allow extensions to change the $oldHeader variable
 363                         Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
 364                                 $diffOnly, $ldel, $this->unhide ] );
 365
 366                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 367                                 $deleted = true; // old revisions text is hidden
 368                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 369                                         $suppressed = true; // also suppressed
 370                                 }
 371                         }
 372
 373                         # Check if this user can see the revisions
 374                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 375                                 $allowed = false;
 376                         }
 377                 }
 378
 379                 # Make "next revision link"
 380                 # Skip next link on the top revision
 381                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 382                         $nextlink = Linker::linkKnown(
 383                                 $this->mNewPage,
 384                                 $this->msg( 'nextdiff' )->escaped(),
 385                                 [ 'id' => 'differences-nextlink' ],
 386                                 [ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
 387                         );
 388                 } else {
 389                         $nextlink = '&#160;';
 390                 }
 391
 392                 if ( $this->mNewRev->isMinor() ) {
 393                         $newminor = ChangesList::flag( 'minor' );
 394                 } else {
 395                         $newminor = '';
 396                 }
 397
 398                 # Handle RevisionDelete links...
 399                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 400
 401                 # Allow extensions to define their own revision tools
 402                 Hooks::run( 'DiffRevisionTools',
 403                         [ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
 404                 $formattedRevisionTools = [];
 405                 // Put each one in parentheses (poor man's button)
 406                 foreach ( $revisionTools as $key => $tool ) {
 407                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 408                         $element = Html::rawElement(
 409                                 'span',
 410                                 [ 'class' => $toolClass ],
 411                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 412                         );
 413                         $formattedRevisionTools[] = $element;
 414                 }
 415                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 416                         ' ' . implode( ' ', $formattedRevisionTools );
 417                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );
 418
 419                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 420                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 421                         " $rollback</div>" .
 422                         '<div id="mw-diff-ntitle3">' . $newminor .
 423                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 424                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 425                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 426
 427                 // Allow extensions to change the $newHeader variable
 428                 Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
 429                         $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
 430
 431                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 432                         $deleted = true; // new revisions text is hidden
 433                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 434                                 $suppressed = true; // also suppressed
 435                         }
 436                 }
 437
 438                 # If the diff cannot be shown due to a deleted revision, then output
 439                 # the diff header and links to unhide (if available)...
 440                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 441                         $this->showDiffStyle();
 442                         $multi = $this->getMultiNotice();
 443                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 444                         if ( !$allowed ) {
 445                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 446                                 # Give explanation for why revision is not visible
 447                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 448                                         [ $msg ] );
 449                         } else {
 450                                 # Give explanation and add a link to view the diff...
 451                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
 452                                 $link = $this->getTitle()->getFullURL( $query );
 453                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 454                                 $out->wrapWikiMsg(
 455                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 456                                         [ $msg, $link ]
 457                                 );
 458                         }
 459                 # Otherwise, output a regular diff...
 460                 } else {
 461                         # Add deletion notice if the user is viewing deleted content
 462                         $notice = '';
 463                         if ( $deleted ) {
 464                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 465                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 466                                         $this->msg( $msg )->parse() .
 467                                         "</div>\n";
 468                         }
 469                         $this->showDiff( $oldHeader, $newHeader, $notice );
 470                         if ( !$diffOnly ) {
 471                                 $this->renderNewRevision();
 472                         }
 473                 }
 474         }
 475
 476         /**
 477          * Build a link to mark a change as patrolled.
 478          *
 479          * Returns empty string if there's either no revision to patrol or the user is not allowed to.
 480          * Side effect: When the patrol link is build, this method will call
 481          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 482          *
 483          * @return string HTML or empty string
 484          */
 485         public function markPatrolledLink() {
 486                 if ( $this->mMarkPatrolledLink === null ) {
 487                         $linkInfo = $this->getMarkPatrolledLinkInfo();
 488                         // If false, there is no patrol link needed/allowed
 489                         if ( !$linkInfo ) {
 490                                 $this->mMarkPatrolledLink = '';
 491                         } else {
 492                                 $this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
 493                                         Linker::linkKnown(
 494                                                 $this->mNewPage,
 495                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 496                                                 [],
 497                                                 [
 498                                                         'action' => 'markpatrolled',
 499                                                         'rcid' => $linkInfo['rcid'],
 500                                                 ]
 501                                         ) . ']</span>';
 502                                 // Allow extensions to change the markpatrolled link
 503                                 Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
 504                                         &$this->mMarkPatrolledLink, $linkInfo['rcid'] ] );
 505                         }
 506                 }
 507                 return $this->mMarkPatrolledLink;
 508         }
 509
 510         /**
 511          * Returns an array of meta data needed to build a "mark as patrolled" link and
 512          * adds the mediawiki.page.patrol.ajax to the output.
 513          *
 514          * @return array|false An array of meta data for a patrol link (rcid only)
 515          *  or false if no link is needed
 516          */
 517         protected function getMarkPatrolledLinkInfo() {
 518                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 519
 520                 $user = $this->getUser();
 521
 522                 // Prepare a change patrol link, if applicable
 523                 if (
 524                         // Is patrolling enabled and the user allowed to?
 525                         $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 526                         // Only do this if the revision isn't more than 6 hours older
 527                         // than the Max RC age (6h because the RC might not be cleaned out regularly)
 528                         RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 529                 ) {
 530                         // Look for an unpatrolled change corresponding to this diff
 531                         $db = wfGetDB( DB_REPLICA );
 532                         $change = RecentChange::newFromConds(
 533                                 [
 534                                         'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 535                                         'rc_this_oldid' => $this->mNewid,
 536                                         'rc_patrolled' => 0
 537                                 ],
 538                                 __METHOD__
 539                         );
 540
 541                         if ( $change && !$change->getPerformer()->equals( $user ) ) {
 542                                 $rcid = $change->getAttribute( 'rc_id' );
 543                         } else {
 544                                 // None found or the page has been created by the current user.
 545                                 // If the user could patrol this it already would be patrolled
 546                                 $rcid = 0;
 547                         }
 548
 549                         // Allow extensions to possibly change the rcid here
 550                         // For example the rcid might be set to zero due to the user
 551                         // being the same as the performer of the change but an extension
 552                         // might still want to show it under certain conditions
 553                         Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
 554
 555                         // Build the link
 556                         if ( $rcid ) {
 557                                 $this->getOutput()->preventClickjacking();
 558                                 if ( $wgEnableAPI && $wgEnableWriteAPI
 559                                         && $user->isAllowed( 'writeapi' )
 560                                 ) {
 561                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 562                                 }
 563
 564                                 return [
 565                                         'rcid' => $rcid,
 566                                 ];
 567                         }
 568                 }
 569
 570                 // No mark as patrolled link applicable
 571                 return false;
 572         }
 573
 574         /**
 575          * @param Revision $rev
 576          *
 577          * @return string
 578          */
 579         protected function revisionDeleteLink( $rev ) {
 580                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 581                 if ( $link !== '' ) {
 582                         $link = '&#160;&#160;&#160;' . $link . ' ';
 583                 }
 584
 585                 return $link;
 586         }
 587
 588         /**
 589          * Show the new revision of the page.
 590          */
 591         public function renderNewRevision() {
 592                 $out = $this->getOutput();
 593                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 594                 # Add "current version as of X" title
 595                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 596                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 597                 # Page content may be handled by a hooked call instead...
 598                 # @codingStandardsIgnoreStart Ignoring long lines.
 599                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 600                         $this->loadNewText();
 601                         $out->setRevisionId( $this->mNewid );
 602                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 603                         $out->setArticleFlag( true );
 604
 605                         if ( !Hooks::run( 'ArticleContentViewCustom', [ $this->mNewContent, $this->mNewPage, $out ] ) ) {
 606                                 // Handled by extension
 607                         } else {
 608                                 // Normal page
 609                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 610                                         // If the Title stored in the context is the same as the one
 611                                         // of the new revision, we can use its associated WikiPage
 612                                         // object.
 613                                         $wikiPage = $this->getWikiPage();
 614                                 } else {
 615                                         // Otherwise we need to create our own WikiPage object
 616                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 617                                 }
 618
 619                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 620
 621                                 # WikiPage::getParserOutput() should not return false, but just in case
 622                                 if ( $parserOutput ) {
 623                                         // Allow extensions to change parser output here
 624                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput', [ $this, $out, $parserOutput, $wikiPage ] ) ) {
 625                                                 $out->addParserOutput( $parserOutput );
 626                                         }
 627                                 }
 628                         }
 629                 }
 630                 # @codingStandardsIgnoreEnd
 631
 632                 // Allow extensions to optionally not show the final patrolled link
 633                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 634                         # Add redundant patrol link on bottom...
 635                         $out->addHTML( $this->markPatrolledLink() );
 636                 }
 637         }
 638
 639         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 640                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 641
 642                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 643                         $parserOptions->setEditSection( false );
 644                 }
 645
 646                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 647
 648                 return $parserOutput;
 649         }
 650
 651         /**
 652          * Get the diff text, send it to the OutputPage object
 653          * Returns false if the diff could not be generated, otherwise returns true
 654          *
 655          * @param string|bool $otitle Header for old text or false
 656          * @param string|bool $ntitle Header for new text or false
 657          * @param string $notice HTML between diff header and body
 658          *
 659          * @return bool
 660          */
 661         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 662                 // Allow extensions to affect the output here
 663                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 664
 665                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 666                 if ( $diff === false ) {
 667                         $this->showMissingRevision();
 668
 669                         return false;
 670                 } else {
 671                         $this->showDiffStyle();
 672                         $this->getOutput()->addHTML( $diff );
 673
 674                         return true;
 675                 }
 676         }
 677
 678         /**
 679          * Add style sheets for diff display.
 680          */
 681         public function showDiffStyle() {
 682                 $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 683         }
 684
 685         /**
 686          * Get complete diff table, including header
 687          *
 688          * @param string|bool $otitle Header for old text or false
 689          * @param string|bool $ntitle Header for new text or false
 690          * @param string $notice HTML between diff header and body
 691          *
 692          * @return mixed
 693          */
 694         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 695                 $body = $this->getDiffBody();
 696                 if ( $body === false ) {
 697                         return false;
 698                 }
 699
 700                 $multi = $this->getMultiNotice();
 701                 // Display a message when the diff is empty
 702                 if ( $body === '' ) {
 703                         $notice .= '<div class="mw-diff-empty">' .
 704                                 $this->msg( 'diff-empty' )->parse() .
 705                                 "</div>\n";
 706                 }
 707
 708                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 709         }
 710
 711         /**
 712          * Get the diff table body, without header
 713          *
 714          * @return mixed (string/false)
 715          */
 716         public function getDiffBody() {
 717                 $this->mCacheHit = true;
 718                 // Check if the diff should be hidden from this user
 719                 if ( !$this->loadRevisionData() ) {
 720                         return false;
 721                 } elseif ( $this->mOldRev &&
 722                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 723                 ) {
 724                         return false;
 725                 } elseif ( $this->mNewRev &&
 726                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 727                 ) {
 728                         return false;
 729                 }
 730                 // Short-circuit
 731                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 732                         && $this->mOldRev->getId() == $this->mNewRev->getId() )
 733                 ) {
 734                         if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 735                                 return '';
 736                         }
 737                 }
 738                 // Cacheable?
 739                 $key = false;
 740                 $cache = ObjectCache::getMainWANInstance();
 741                 if ( $this->mOldid && $this->mNewid ) {
 742                         $key = $this->getDiffBodyCacheKey();
 743
 744                         // Try cache
 745                         if ( !$this->mRefreshCache ) {
 746                                 $difftext = $cache->get( $key );
 747                                 if ( $difftext ) {
 748                                         wfIncrStats( 'diff_cache.hit' );
 749                                         $difftext = $this->localiseLineNumbers( $difftext );
 750                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 751
 752                                         return $difftext;
 753                                 }
 754                         } // don't try to load but save the result
 755                 }
 756                 $this->mCacheHit = false;
 757
 758                 // Loadtext is permission safe, this just clears out the diff
 759                 if ( !$this->loadText() ) {
 760                         return false;
 761                 }
 762
 763                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 764
 765                 // Avoid PHP 7.1 warning from passing $this by reference
 766                 $diffEngine = $this;
 767
 768                 // Save to cache for 7 days
 769                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
 770                         wfIncrStats( 'diff_cache.uncacheable' );
 771                 } elseif ( $key !== false && $difftext !== false ) {
 772                         wfIncrStats( 'diff_cache.miss' );
 773                         $cache->set( $key, $difftext, 7 * 86400 );
 774                 } else {
 775                         wfIncrStats( 'diff_cache.uncacheable' );
 776                 }
 777                 // Replace line numbers with the text in the user's language
 778                 if ( $difftext !== false ) {
 779                         $difftext = $this->localiseLineNumbers( $difftext );
 780                 }
 781
 782                 return $difftext;
 783         }
 784
 785         /**
 786          * Returns the cache key for diff body text or content.
 787          *
 788          * @since 1.23
 789          *
 790          * @throws MWException
 791          * @return string
 792          */
 793         protected function getDiffBodyCacheKey() {
 794                 if ( !$this->mOldid || !$this->mNewid ) {
 795                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 796                 }
 797
 798                 return wfMemcKey( 'diff', 'version', self::DIFF_VERSION,
 799                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 800         }
 801
 802         /**
 803          * Generate a diff, no caching.
 804          *
 805          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 806          * serialization of the given Content objects. This will fail if $old or $new are not
 807          * instances of TextContent.
 808          *
 809          * Subclasses may override this to provide a different rendering for the diff,
 810          * perhaps taking advantage of the content's native form. This is required for all content
 811          * models that are not text based.
 812          *
 813          * @since 1.21
 814          *
 815          * @param Content $old Old content
 816          * @param Content $new New content
 817          *
 818          * @throws MWException If old or new content is not an instance of TextContent.
 819          * @return bool|string
 820          */
 821         public function generateContentDiffBody( Content $old, Content $new ) {
 822                 if ( !( $old instanceof TextContent ) ) {
 823                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 824                                 "override generateContentDiffBody to fix this." );
 825                 }
 826
 827                 if ( !( $new instanceof TextContent ) ) {
 828                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 829                                 . "override generateContentDiffBody to fix this." );
 830                 }
 831
 832                 $otext = $old->serialize();
 833                 $ntext = $new->serialize();
 834
 835                 return $this->generateTextDiffBody( $otext, $ntext );
 836         }
 837
 838         /**
 839          * Generate a diff, no caching
 840          *
 841          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 842          *
 843          * @param string $otext Old text, must be already segmented
 844          * @param string $ntext New text, must be already segmented
 845          *
 846          * @return bool|string
 847          */
 848         public function generateTextDiffBody( $otext, $ntext ) {
 849                 $diff = function() use ( $otext, $ntext ) {
 850                         $time = microtime( true );
 851
 852                         $result = $this->textDiff( $otext, $ntext );
 853
 854                         $time = intval( ( microtime( true ) - $time ) * 1000 );
 855                         $this->getStats()->timing( 'diff_time', $time );
 856                         // Log requests slower than 99th percentile
 857                         if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
 858                                 wfDebugLog( 'diff',
 859                                         "$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
 860                         }
 861
 862                         return $result;
 863                 };
 864
 865                 /**
 866                  * @param Status $status
 867                  * @throws FatalError
 868                  */
 869                 $error = function( $status ) {
 870                         throw new FatalError( $status->getWikiText() );
 871                 };
 872
 873                 // Use PoolCounter if the diff looks like it can be expensive
 874                 if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
 875                         $work = new PoolCounterWorkViaCallback( 'diff',
 876                                 md5( $otext ) . md5( $ntext ),
 877                                 [ 'doWork' => $diff, 'error' => $error ]
 878                         );
 879                         return $work->execute();
 880                 }
 881
 882                 return $diff();
 883         }
 884
 885         /**
 886          * Generates diff, to be wrapped internally in a logging/instrumentation
 887          *
 888          * @param string $otext Old text, must be already segmented
 889          * @param string $ntext New text, must be already segmented
 890          * @return bool|string
 891          */
 892         protected function textDiff( $otext, $ntext ) {
 893                 global $wgExternalDiffEngine, $wgContLang;
 894
 895                 $otext = str_replace( "\r\n", "\n", $otext );
 896                 $ntext = str_replace( "\r\n", "\n", $ntext );
 897
 898                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
 899                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
 900                         $wgExternalDiffEngine = false;
 901                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
 902                         // Same as above, but with no deprecation warnings
 903                         $wgExternalDiffEngine = false;
 904                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
 905                         // And prevent people from shooting themselves in the foot...
 906                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
 907                         $wgExternalDiffEngine = false;
 908                 }
 909
 910                 if ( function_exists( 'wikidiff2_do_diff' ) && $wgExternalDiffEngine === false ) {
 911                         # Better external diff engine, the 2 may some day be dropped
 912                         # This one does the escaping and segmenting itself
 913                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 914                         $text .= $this->debug( 'wikidiff2' );
 915
 916                         return $text;
 917                 } elseif ( $wgExternalDiffEngine !== false && is_executable( $wgExternalDiffEngine ) ) {
 918                         # Diff via the shell
 919                         $tmpDir = wfTempDir();
 920                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 921                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 922
 923                         $tempFile1 = fopen( $tempName1, "w" );
 924                         if ( !$tempFile1 ) {
 925                                 return false;
 926                         }
 927                         $tempFile2 = fopen( $tempName2, "w" );
 928                         if ( !$tempFile2 ) {
 929                                 return false;
 930                         }
 931                         fwrite( $tempFile1, $otext );
 932                         fwrite( $tempFile2, $ntext );
 933                         fclose( $tempFile1 );
 934                         fclose( $tempFile2 );
 935                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 936                         $difftext = wfShellExec( $cmd );
 937                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 938                         unlink( $tempName1 );
 939                         unlink( $tempName2 );
 940
 941                         return $difftext;
 942                 }
 943
 944                 # Native PHP diff
 945                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 946                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 947                 $diffs = new Diff( $ota, $nta );
 948                 $formatter = new TableDiffFormatter();
 949                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 950
 951                 return $difftext;
 952         }
 953
 954         /**
 955          * Generate a debug comment indicating diff generating time,
 956          * server node, and generator backend.
 957          *
 958          * @param string $generator : What diff engine was used
 959          *
 960          * @return string
 961          */
 962         protected function debug( $generator = "internal" ) {
 963                 global $wgShowHostnames;
 964                 if ( !$this->enableDebugComment ) {
 965                         return '';
 966                 }
 967                 $data = [ $generator ];
 968                 if ( $wgShowHostnames ) {
 969                         $data[] = wfHostname();
 970                 }
 971                 $data[] = wfTimestamp( TS_DB );
 972
 973                 return "<!-- diff generator: " .
 974                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
 975                         " -->\n";
 976         }
 977
 978         /**
 979          * Replace line numbers with the text in the user's language
 980          *
 981          * @param string $text
 982          *
 983          * @return mixed
 984          */
 985         public function localiseLineNumbers( $text ) {
 986                 return preg_replace_callback(
 987                         '/<!--LINE (\d+)-->/',
 988                         [ $this, 'localiseLineNumbersCb' ],
 989                         $text
 990                 );
 991         }
 992
 993         public function localiseLineNumbersCb( $matches ) {
 994                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
 995                         return '';
 996                 }
 997
 998                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 999         }
1000
1001         /**
1002          * If there are revisions between the ones being compared, return a note saying so.
1003          *
1004          * @return string
1005          */
1006         public function getMultiNotice() {
1007                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
1008                         return '';
1009                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
1010                         // Comparing two different pages? Count would be meaningless.
1011                         return '';
1012                 }
1013
1014                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1015                         $oldRev = $this->mNewRev; // flip
1016                         $newRev = $this->mOldRev; // flip
1017                 } else { // normal case
1018                         $oldRev = $this->mOldRev;
1019                         $newRev = $this->mNewRev;
1020                 }
1021
1022                 // Sanity: don't show the notice if too many rows must be scanned
1023                 // @todo show some special message for that case
1024                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1025                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1026                         $limit = 100; // use diff-multi-manyusers if too many users
1027                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1028                         $numUsers = count( $users );
1029
1030                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1031                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1032                         }
1033
1034                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1035                 }
1036
1037                 return ''; // nothing
1038         }
1039
1040         /**
1041          * Get a notice about how many intermediate edits and users there are
1042          *
1043          * @param int $numEdits
1044          * @param int $numUsers
1045          * @param int $limit
1046          *
1047          * @return string
1048          */
1049         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1050                 if ( $numUsers === 0 ) {
1051                         $msg = 'diff-multi-sameuser';
1052                 } elseif ( $numUsers > $limit ) {
1053                         $msg = 'diff-multi-manyusers';
1054                         $numUsers = $limit;
1055                 } else {
1056                         $msg = 'diff-multi-otherusers';
1057                 }
1058
1059                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1060         }
1061
1062         /**
1063          * Get a header for a specified revision.
1064          *
1065          * @param Revision $rev
1066          * @param string $complete 'complete' to get the header wrapped depending
1067          *        the visibility of the revision and a link to edit the page.
1068          *
1069          * @return string HTML fragment
1070          */
1071         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1072                 $lang = $this->getLanguage();
1073                 $user = $this->getUser();
1074                 $revtimestamp = $rev->getTimestamp();
1075                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1076                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1077                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1078
1079                 $header = $this->msg(
1080                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1081                         $timestamp,
1082                         $dateofrev,
1083                         $timeofrev
1084                 )->escaped();
1085
1086                 if ( $complete !== 'complete' ) {
1087                         return $header;
1088                 }
1089
1090                 $title = $rev->getTitle();
1091
1092                 $header = Linker::linkKnown( $title, $header, [],
1093                         [ 'oldid' => $rev->getId() ] );
1094
1095                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1096                         $editQuery = [ 'action' => 'edit' ];
1097                         if ( !$rev->isCurrent() ) {
1098                                 $editQuery['oldid'] = $rev->getId();
1099                         }
1100
1101                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1102                         $msg = $this->msg( $key )->escaped();
1103                         $editLink = $this->msg( 'parentheses' )->rawParams(
1104                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1105                         $header .= ' ' . Html::rawElement(
1106                                 'span',
1107                                 [ 'class' => 'mw-diff-edit' ],
1108                                 $editLink
1109                         );
1110                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1111                                 $header = Html::rawElement(
1112                                         'span',
1113                                         [ 'class' => 'history-deleted' ],
1114                                         $header
1115                                 );
1116                         }
1117                 } else {
1118                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1119                 }
1120
1121                 return $header;
1122         }
1123
1124         /**
1125          * Add the header to a diff body
1126          *
1127          * @param string $diff Diff body
1128          * @param string $otitle Old revision header
1129          * @param string $ntitle New revision header
1130          * @param string $multi Notice telling user that there are intermediate
1131          *   revisions between the ones being compared
1132          * @param string $notice Other notices, e.g. that user is viewing deleted content
1133          *
1134          * @return string
1135          */
1136         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1137                 // shared.css sets diff in interface language/dir, but the actual content
1138                 // is often in a different language, mostly the page content language/dir
1139                 $header = Html::openElement( 'table', [
1140                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1141                         'data-mw' => 'interface',
1142                 ] );
1143                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1144
1145                 if ( !$diff && !$otitle ) {
1146                         $header .= "
1147                         <tr style='vertical-align: top;' lang='{$userLang}'>
1148                         <td class='diff-ntitle'>{$ntitle}</td>
1149                         </tr>";
1150                         $multiColspan = 1;
1151                 } else {
1152                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1153                                 $header .= "
1154                                 <col class='diff-marker' />
1155                                 <col class='diff-content' />
1156                                 <col class='diff-marker' />
1157                                 <col class='diff-content' />";
1158                                 $colspan = 2;
1159                                 $multiColspan = 4;
1160                         } else {
1161                                 $colspan = 1;
1162                                 $multiColspan = 2;
1163                         }
1164                         if ( $otitle || $ntitle ) {
1165                                 $header .= "
1166                                 <tr style='vertical-align: top;' lang='{$userLang}'>
1167                                 <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
1168                                 <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
1169                                 </tr>";
1170                         }
1171                 }
1172
1173                 if ( $multi != '' ) {
1174                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1175                                 "class='diff-multi' lang='{$userLang}'>{$multi}</td></tr>";
1176                 }
1177                 if ( $notice != '' ) {
1178                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1179                                 "lang='{$userLang}'>{$notice}</td></tr>";
1180                 }
1181
1182                 return $header . $diff . "</table>";
1183         }
1184
1185         /**
1186          * Use specified text instead of loading from the database
1187          * @param Content $oldContent
1188          * @param Content $newContent
1189          * @since 1.21
1190          */
1191         public function setContent( Content $oldContent, Content $newContent ) {
1192                 $this->mOldContent = $oldContent;
1193                 $this->mNewContent = $newContent;
1194
1195                 $this->mTextLoaded = 2;
1196                 $this->mRevisionsLoaded = true;
1197         }
1198
1199         /**
1200          * Set the language in which the diff text is written
1201          * (Defaults to page content language).
1202          * @param Language|string $lang
1203          * @since 1.19
1204          */
1205         public function setTextLanguage( $lang ) {
1206                 $this->mDiffLang = wfGetLangObj( $lang );
1207         }
1208
1209         /**
1210          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1211          * to a pair of actual integers representing revision ids.
1212          *
1213          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1214          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1215          *
1216          * @return int[] List of two revision ids, older first, later second.
1217          *     Zero signifies invalid argument passed.
1218          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1219          */
1220         public function mapDiffPrevNext( $old, $new ) {
1221                 if ( $new === 'prev' ) {
1222                         // Show diff between revision $old and the previous one. Get previous one from DB.
1223                         $newid = intval( $old );
1224                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1225                 } elseif ( $new === 'next' ) {
1226                         // Show diff between revision $old and the next one. Get next one from DB.
1227                         $oldid = intval( $old );
1228                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1229                 } else {
1230                         $oldid = intval( $old );
1231                         $newid = intval( $new );
1232                 }
1233
1234                 return [ $oldid, $newid ];
1235         }
1236
1237         /**
1238          * Load revision IDs
1239          */
1240         private function loadRevisionIds() {
1241                 if ( $this->mRevisionsIdsLoaded ) {
1242                         return;
1243                 }
1244
1245                 $this->mRevisionsIdsLoaded = true;
1246
1247                 $old = $this->mOldid;
1248                 $new = $this->mNewid;
1249
1250                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1251                 if ( $new === 'next' && $this->mNewid === false ) {
1252                         # if no result, NewId points to the newest old revision. The only newer
1253                         # revision is cur, which is "0".
1254                         $this->mNewid = 0;
1255                 }
1256
1257                 Hooks::run(
1258                         'NewDifferenceEngine',
1259                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1260                 );
1261         }
1262
1263         /**
1264          * Load revision metadata for the specified articles. If newid is 0, then compare
1265          * the old article in oldid to the current article; if oldid is 0, then
1266          * compare the current article to the immediately previous one (ignoring the
1267          * value of newid).
1268          *
1269          * If oldid is false, leave the corresponding revision object set
1270          * to false. This is impossible via ordinary user input, and is provided for
1271          * API convenience.
1272          *
1273          * @return bool
1274          */
1275         public function loadRevisionData() {
1276                 if ( $this->mRevisionsLoaded ) {
1277                         return true;
1278                 }
1279
1280                 // Whether it succeeds or fails, we don't want to try again
1281                 $this->mRevisionsLoaded = true;
1282
1283                 $this->loadRevisionIds();
1284
1285                 // Load the new revision object
1286                 if ( $this->mNewid ) {
1287                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1288                 } else {
1289                         $this->mNewRev = Revision::newFromTitle(
1290                                 $this->getTitle(),
1291                                 false,
1292                                 Revision::READ_NORMAL
1293                         );
1294                 }
1295
1296                 if ( !$this->mNewRev instanceof Revision ) {
1297                         return false;
1298                 }
1299
1300                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1301                 $this->mNewid = $this->mNewRev->getId();
1302                 $this->mNewPage = $this->mNewRev->getTitle();
1303
1304                 // Load the old revision object
1305                 $this->mOldRev = false;
1306                 if ( $this->mOldid ) {
1307                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1308                 } elseif ( $this->mOldid === 0 ) {
1309                         $rev = $this->mNewRev->getPrevious();
1310                         if ( $rev ) {
1311                                 $this->mOldid = $rev->getId();
1312                                 $this->mOldRev = $rev;
1313                         } else {
1314                                 // No previous revision; mark to show as first-version only.
1315                                 $this->mOldid = false;
1316                                 $this->mOldRev = false;
1317                         }
1318                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1319
1320                 if ( is_null( $this->mOldRev ) ) {
1321                         return false;
1322                 }
1323
1324                 if ( $this->mOldRev ) {
1325                         $this->mOldPage = $this->mOldRev->getTitle();
1326                 }
1327
1328                 // Load tags information for both revisions
1329                 $dbr = wfGetDB( DB_REPLICA );
1330                 if ( $this->mOldid !== false ) {
1331                         $this->mOldTags = $dbr->selectField(
1332                                 'tag_summary',
1333                                 'ts_tags',
1334                                 [ 'ts_rev_id' => $this->mOldid ],
1335                                 __METHOD__
1336                         );
1337                 } else {
1338                         $this->mOldTags = false;
1339                 }
1340                 $this->mNewTags = $dbr->selectField(
1341                         'tag_summary',
1342                         'ts_tags',
1343                         [ 'ts_rev_id' => $this->mNewid ],
1344                         __METHOD__
1345                 );
1346
1347                 return true;
1348         }
1349
1350         /**
1351          * Load the text of the revisions, as well as revision data.
1352          *
1353          * @return bool
1354          */
1355         public function loadText() {
1356                 if ( $this->mTextLoaded == 2 ) {
1357                         return true;
1358                 }
1359
1360                 // Whether it succeeds or fails, we don't want to try again
1361                 $this->mTextLoaded = 2;
1362
1363                 if ( !$this->loadRevisionData() ) {
1364                         return false;
1365                 }
1366
1367                 if ( $this->mOldRev ) {
1368                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1369                         if ( $this->mOldContent === null ) {
1370                                 return false;
1371                         }
1372                 }
1373
1374                 if ( $this->mNewRev ) {
1375                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1376                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1377                         if ( $this->mNewContent === null ) {
1378                                 return false;
1379                         }
1380                 }
1381
1382                 return true;
1383         }
1384
1385         /**
1386          * Load the text of the new revision, not the old one
1387          *
1388          * @return bool
1389          */
1390         public function loadNewText() {
1391                 if ( $this->mTextLoaded >= 1 ) {
1392                         return true;
1393                 }
1394
1395                 $this->mTextLoaded = 1;
1396
1397                 if ( !$this->loadRevisionData() ) {
1398                         return false;
1399                 }
1400
1401                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1402
1403                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1404
1405                 return true;
1406         }
1407
1408 }