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 use MediaWiki\MediaWikiServices;
  25 use MediaWiki\Permissions\PermissionManager;
  26 use MediaWiki\Revision\RevisionRecord;
  27 use MediaWiki\Revision\SlotRecord;
  28 use MediaWiki\Storage\NameTableAccessException;
  29
  30 /**
  31  * DifferenceEngine is responsible for rendering the difference between two revisions as HTML.
  32  * This includes interpreting URL parameters, retrieving revision data, checking access permissions,
  33  * selecting and invoking the diff generator class for the individual slots, doing post-processing
  34  * on the generated diff, adding the rest of the HTML (such as headers) and writing the whole thing
  35  * to OutputPage.
  36  *
  37  * DifferenceEngine can be subclassed by extensions, by customizing
  38  * ContentHandler::createDifferenceEngine; the content handler will be selected based on the
  39  * content model of the main slot (of the new revision, when the two are different).
  40  * That might change after PageTypeHandler gets introduced.
  41  *
  42  * In the past, the class was also used for slot-level diff generation, and extensions might still
  43  * subclass it and add such functionality. When that is the case (sepcifically, when a
  44  * ContentHandler returns a standard SlotDiffRenderer but a nonstandard DifferenceEngine)
  45  * DifferenceEngineSlotDiffRenderer will be used to convert the old behavior into the new one.
  46  *
  47  * @ingroup DifferenceEngine
  48  *
  49  * @todo This class is huge and poorly defined. It should be split into a controller responsible
  50  * for interpreting query parameters, retrieving data and checking permissions; and a HTML renderer.
  51  */
  52 class DifferenceEngine extends ContextSource {
  53
  54         use DeprecationHelper;
  55
  56         /**
  57          * Constant to indicate diff cache compatibility.
  58          * Bump this when changing the diff formatting in a way that
  59          * fixes important bugs or such to force cached diff views to
  60          * clear.
  61          */
  62         const DIFF_VERSION = '1.12';
  63
  64         /**
  65          * Revision ID for the old revision. 0 for the revision previous to $mNewid, false
  66          * if the diff does not have an old revision (e.g. 'oldid=<first revision of page>&diff=prev'),
  67          * or the revision does not exist, null if the revision is unsaved.
  68          * @var int|false|null
  69          */
  70         protected $mOldid;
  71
  72         /**
  73          * Revision ID for the new revision. 0 for the last revision of the current page
  74          * (as defined by the request context), false if the revision does not exist, null
  75          * if it is unsaved, or an alias such as 'next'.
  76          * @var int|string|false|null
  77          */
  78         protected $mNewid;
  79
  80         /**
  81          * Old revision (left pane).
  82          * Allowed to be an unsaved revision, unlikely that's ever needed though.
  83          * False when the old revision does not exist; this can happen when using
  84          * diff=prev on the first revision. Null when the revision should exist but
  85          * doesn't (e.g. load failure); loadRevisionData() will return false in that
  86          * case. Also null until lazy-loaded. Ignored completely when isContentOverridden
  87          * is set.
  88          * Since 1.32 public access is deprecated.
  89          * @var Revision|null|false
  90          */
  91         protected $mOldRev;
  92
  93         /**
  94          * New revision (right pane).
  95          * Note that this might be an unsaved revision (e.g. for edit preview).
  96          * Null in case of load failure; diff methods will just return an error message in that case,
  97          * and loadRevisionData() will return false. Also null until lazy-loaded. Ignored completely
  98          * when isContentOverridden is set.
  99          * Since 1.32 public access is deprecated.
 100          * @var Revision|null
 101          */
 102         protected $mNewRev;
 103
 104         /**
 105          * Title of $mOldRev or null if the old revision does not exist or does not belong to a page.
 106          * Since 1.32 public access is deprecated and the property can be null.
 107          * @var Title|null
 108          */
 109         protected $mOldPage;
 110
 111         /**
 112          * Title of $mNewRev or null if the new revision does not exist or does not belong to a page.
 113          * Since 1.32 public access is deprecated and the property can be null.
 114          * @var Title|null
 115          */
 116         protected $mNewPage;
 117
 118         /**
 119          * Change tags of $mOldRev or null if it does not exist / is not saved.
 120          * @var string[]|null
 121          */
 122         private $mOldTags;
 123
 124         /**
 125          * Change tags of $mNewRev or null if it does not exist / is not saved.
 126          * @var string[]|null
 127          */
 128         private $mNewTags;
 129
 130         /**
 131          * @var Content|null
 132          * @deprecated since 1.32, content slots are now handled by the corresponding SlotDiffRenderer.
 133          *   This property is set to the content of the main slot, but not actually used for the main diff.
 134          */
 135         private $mOldContent;
 136
 137         /**
 138          * @var Content|null
 139          * @deprecated since 1.32, content slots are now handled by the corresponding SlotDiffRenderer.
 140          *   This property is set to the content of the main slot, but not actually used for the main diff.
 141          */
 142         private $mNewContent;
 143
 144         /** @var Language */
 145         protected $mDiffLang;
 146
 147         /** @var bool Have the revisions IDs been loaded */
 148         private $mRevisionsIdsLoaded = false;
 149
 150         /** @var bool Have the revisions been loaded */
 151         protected $mRevisionsLoaded = false;
 152
 153         /** @var int How many text blobs have been loaded, 0, 1 or 2? */
 154         protected $mTextLoaded = 0;
 155
 156         /**
 157          * Was the content overridden via setContent()?
 158          * If the content was overridden, most internal state (e.g. mOldid or mOldRev) should be ignored
 159          * and only mOldContent and mNewContent is reliable.
 160          * (Note that setRevisions() does not set this flag as in that case all properties are
 161          * overriden and remain consistent with each other, so no special handling is needed.)
 162          * @var bool
 163          */
 164         protected $isContentOverridden = false;
 165
 166         /** @var bool Was the diff fetched from cache? */
 167         protected $mCacheHit = false;
 168
 169         /**
 170          * Set this to true to add debug info to the HTML output.
 171          * Warning: this may cause RSS readers to spuriously mark articles as "new"
 172          * (T22601)
 173          */
 174         public $enableDebugComment = false;
 175
 176         /** @var bool If true, line X is not displayed when X is 1, for example
 177          *    to increase readability and conserve space with many small diffs.
 178          */
 179         protected $mReducedLineNumbers = false;
 180
 181         /** @var string Link to action=markpatrolled */
 182         protected $mMarkPatrolledLink = null;
 183
 184         /** @var bool Show rev_deleted content if allowed */
 185         protected $unhide = false;
 186
 187         /** @var bool Refresh the diff cache */
 188         protected $mRefreshCache = false;
 189
 190         /** @var SlotDiffRenderer[] DifferenceEngine classes for the slots, keyed by role name. */
 191         protected $slotDiffRenderers = null;
 192
 193         /**
 194          * Temporary hack for B/C while slot diff related methods of DifferenceEngine are being
 195          * deprecated. When true, we are inside a DifferenceEngineSlotDiffRenderer and
 196          * $slotDiffRenderers should not be used.
 197          * @var bool
 198          */
 199         protected $isSlotDiffRenderer = false;
 200
 201         /**#@-*/
 202
 203         /**
 204          * @param IContextSource|null $context Context to use, anything else will be ignored
 205          * @param int $old Old ID we want to show and diff with.
 206          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 207          * @param int $rcid Deprecated, no longer used!
 208          * @param bool $refreshCache If set, refreshes the diff cache
 209          * @param bool $unhide If set, allow viewing deleted revs
 210          */
 211         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 212                 $refreshCache = false, $unhide = false
 213         ) {
 214                 $this->deprecatePublicProperty( 'mOldid', '1.32', __CLASS__ );
 215                 $this->deprecatePublicProperty( 'mNewid', '1.32', __CLASS__ );
 216                 $this->deprecatePublicProperty( 'mOldRev', '1.32', __CLASS__ );
 217                 $this->deprecatePublicProperty( 'mNewRev', '1.32', __CLASS__ );
 218                 $this->deprecatePublicProperty( 'mOldPage', '1.32', __CLASS__ );
 219                 $this->deprecatePublicProperty( 'mNewPage', '1.32', __CLASS__ );
 220                 $this->deprecatePublicProperty( 'mOldContent', '1.32', __CLASS__ );
 221                 $this->deprecatePublicProperty( 'mNewContent', '1.32', __CLASS__ );
 222                 $this->deprecatePublicProperty( 'mRevisionsLoaded', '1.32', __CLASS__ );
 223                 $this->deprecatePublicProperty( 'mTextLoaded', '1.32', __CLASS__ );
 224                 $this->deprecatePublicProperty( 'mCacheHit', '1.32', __CLASS__ );
 225
 226                 if ( $context instanceof IContextSource ) {
 227                         $this->setContext( $context );
 228                 }
 229
 230                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 231
 232                 $this->mOldid = $old;
 233                 $this->mNewid = $new;
 234                 $this->mRefreshCache = $refreshCache;
 235                 $this->unhide = $unhide;
 236         }
 237
 238         /**
 239          * @return SlotDiffRenderer[] Diff renderers for each slot, keyed by role name.
 240          *   Includes slots only present in one of the revisions.
 241          */
 242         protected function getSlotDiffRenderers() {
 243                 if ( $this->isSlotDiffRenderer ) {
 244                         throw new LogicException( __METHOD__ . ' called in slot diff renderer mode' );
 245                 }
 246
 247                 if ( $this->slotDiffRenderers === null ) {
 248                         if ( !$this->loadRevisionData() ) {
 249                                 return [];
 250                         }
 251
 252                         $slotContents = $this->getSlotContents();
 253                         $this->slotDiffRenderers = array_map( function ( $contents ) {
 254                                 /** @var Content $content */
 255                                 $content = $contents['new'] ?: $contents['old'];
 256                                 return $content->getContentHandler()->getSlotDiffRenderer( $this->getContext() );
 257                         }, $slotContents );
 258                 }
 259                 return $this->slotDiffRenderers;
 260         }
 261
 262         /**
 263          * Mark this DifferenceEngine as a slot renderer (as opposed to a page renderer).
 264          * This is used in legacy mode when the DifferenceEngine is wrapped in a
 265          * DifferenceEngineSlotDiffRenderer.
 266          * @internal For use by DifferenceEngineSlotDiffRenderer only.
 267          */
 268         public function markAsSlotDiffRenderer() {
 269                 $this->isSlotDiffRenderer = true;
 270         }
 271
 272         /**
 273          * Get the old and new content objects for all slots.
 274          * This method does not do any permission checks.
 275          * @return array [ role => [ 'old' => SlotRecord|null, 'new' => SlotRecord|null ], ... ]
 276          */
 277         protected function getSlotContents() {
 278                 if ( $this->isContentOverridden ) {
 279                         return [
 280                                 SlotRecord::MAIN => [
 281                                         'old' => $this->mOldContent,
 282                                         'new' => $this->mNewContent,
 283                                 ]
 284                         ];
 285                 } elseif ( !$this->loadRevisionData() ) {
 286                         return [];
 287                 }
 288
 289                 $newSlots = $this->mNewRev->getRevisionRecord()->getSlots()->getSlots();
 290                 if ( $this->mOldRev ) {
 291                         $oldSlots = $this->mOldRev->getRevisionRecord()->getSlots()->getSlots();
 292                 } else {
 293                         $oldSlots = [];
 294                 }
 295                 // The order here will determine the visual order of the diff. The current logic is
 296                 // slots of the new revision first in natural order, then deleted ones. This is ad hoc
 297                 // and should not be relied on - in the future we may want the ordering to depend
 298                 // on the page type.
 299                 $roles = array_merge( array_keys( $newSlots ), array_keys( $oldSlots ) );
 300
 301                 $slots = [];
 302                 foreach ( $roles as $role ) {
 303                         $slots[$role] = [
 304                                 'old' => isset( $oldSlots[$role] ) ? $oldSlots[$role]->getContent() : null,
 305                                 'new' => isset( $newSlots[$role] ) ? $newSlots[$role]->getContent() : null,
 306                         ];
 307                 }
 308                 // move main slot to front
 309                 if ( isset( $slots[SlotRecord::MAIN] ) ) {
 310                         $slots = [ SlotRecord::MAIN => $slots[SlotRecord::MAIN] ] + $slots;
 311                 }
 312                 return $slots;
 313         }
 314
 315         public function getTitle() {
 316                 // T202454 avoid errors when there is no title
 317                 return parent::getTitle() ?: Title::makeTitle( NS_SPECIAL, 'BadTitle/DifferenceEngine' );
 318         }
 319
 320         /**
 321          * Set reduced line numbers mode.
 322          * When set, line X is not displayed when X is 1, for example to increase readability and
 323          * conserve space with many small diffs.
 324          * @param bool $value
 325          */
 326         public function setReducedLineNumbers( $value = true ) {
 327                 $this->mReducedLineNumbers = $value;
 328         }
 329
 330         /**
 331          * Get the language of the difference engine, defaults to page content language
 332          *
 333          * @return Language
 334          */
 335         public function getDiffLang() {
 336                 if ( $this->mDiffLang === null ) {
 337                         # Default language in which the diff text is written.
 338                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 339                 }
 340
 341                 return $this->mDiffLang;
 342         }
 343
 344         /**
 345          * @return bool
 346          */
 347         public function wasCacheHit() {
 348                 return $this->mCacheHit;
 349         }
 350
 351         /**
 352          * Get the ID of old revision (left pane) of the diff. 0 for the revision
 353          * previous to getNewid(), false if the old revision does not exist, null
 354          * if it's unsaved.
 355          * To get a real revision ID instead of 0, call loadRevisionData() first.
 356          * @return int|false|null
 357          */
 358         public function getOldid() {
 359                 $this->loadRevisionIds();
 360
 361                 return $this->mOldid;
 362         }
 363
 364         /**
 365          * Get the ID of new revision (right pane) of the diff. 0 for the current revision,
 366          * false if the new revision does not exist, null if it's unsaved.
 367          * To get a real revision ID instead of 0, call loadRevisionData() first.
 368          * @return int|false|null
 369          */
 370         public function getNewid() {
 371                 $this->loadRevisionIds();
 372
 373                 return $this->mNewid;
 374         }
 375
 376         /**
 377          * Get the left side of the diff.
 378          * Could be null when the first revision of the page is diffed to 'prev' (or in the case of
 379          * load failure).
 380          * @return RevisionRecord|null
 381          */
 382         public function getOldRevision() {
 383                 return $this->mOldRev ? $this->mOldRev->getRevisionRecord() : null;
 384         }
 385
 386         /**
 387          * Get the right side of the diff.
 388          * Should not be null but can still happen in the case of load failure.
 389          * @return RevisionRecord|null
 390          */
 391         public function getNewRevision() {
 392                 return $this->mNewRev ? $this->mNewRev->getRevisionRecord() : null;
 393         }
 394
 395         /**
 396          * Look up a special:Undelete link to the given deleted revision id,
 397          * as a workaround for being unable to load deleted diffs in currently.
 398          *
 399          * @param int $id Revision ID
 400          *
 401          * @return string|bool Link HTML or false
 402          */
 403         public function deletedLink( $id ) {
 404                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 405                         $dbr = wfGetDB( DB_REPLICA );
 406                         $arQuery = Revision::getArchiveQueryInfo();
 407                         $row = $dbr->selectRow(
 408                                 $arQuery['tables'],
 409                                 array_merge( $arQuery['fields'], [ 'ar_namespace', 'ar_title' ] ),
 410                                 [ 'ar_rev_id' => $id ],
 411                                 __METHOD__,
 412                                 [],
 413                                 $arQuery['joins']
 414                         );
 415                         if ( $row ) {
 416                                 $rev = Revision::newFromArchiveRow( $row );
 417                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 418
 419                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
 420                                         'target' => $title->getPrefixedText(),
 421                                         'timestamp' => $rev->getTimestamp()
 422                                 ] );
 423                         }
 424                 }
 425
 426                 return false;
 427         }
 428
 429         /**
 430          * Build a wikitext link toward a deleted revision, if viewable.
 431          *
 432          * @param int $id Revision ID
 433          *
 434          * @return string Wikitext fragment
 435          */
 436         public function deletedIdMarker( $id ) {
 437                 $link = $this->deletedLink( $id );
 438                 if ( $link ) {
 439                         return "[$link $id]";
 440                 } else {
 441                         return (string)$id;
 442                 }
 443         }
 444
 445         private function showMissingRevision() {
 446                 $out = $this->getOutput();
 447
 448                 $missing = [];
 449                 if ( $this->mOldRev === null ||
 450                         ( $this->mOldRev && $this->mOldContent === null )
 451                 ) {
 452                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 453                 }
 454                 if ( $this->mNewRev === null ||
 455                         ( $this->mNewRev && $this->mNewContent === null )
 456                 ) {
 457                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 458                 }
 459
 460                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 461                 $msg = $this->msg( 'difference-missing-revision' )
 462                         ->params( $this->getLanguage()->listToText( $missing ) )
 463                         ->numParams( count( $missing ) )
 464                         ->parseAsBlock();
 465                 $out->addHTML( $msg );
 466         }
 467
 468         public function showDiffPage( $diffOnly = false ) {
 469                 # Allow frames except in certain special cases
 470                 $out = $this->getOutput();
 471                 $out->allowClickjacking();
 472                 $out->setRobotPolicy( 'noindex,nofollow' );
 473
 474                 // Allow extensions to add any extra output here
 475                 Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
 476
 477                 if ( !$this->loadRevisionData() ) {
 478                         if ( Hooks::run( 'DifferenceEngineShowDiffPageMaybeShowMissingRevision', [ $this ] ) ) {
 479                                 $this->showMissingRevision();
 480                         }
 481                         return;
 482                 }
 483
 484                 $user = $this->getUser();
 485                 $permErrors = [];
 486                 if ( $this->mNewPage ) {
 487                         $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 488                 }
 489                 if ( $this->mOldPage ) {
 490                         $permErrors = wfMergeErrorArrays( $permErrors,
 491                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 492                 }
 493                 if ( count( $permErrors ) ) {
 494                         throw new PermissionsError( 'read', $permErrors );
 495                 }
 496
 497                 $rollback = '';
 498
 499                 $query = [];
 500                 # Carry over 'diffonly' param via navigation links
 501                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 502                         $query['diffonly'] = $diffOnly;
 503                 }
 504                 # Cascade unhide param in links for easy deletion browsing
 505                 if ( $this->unhide ) {
 506                         $query['unhide'] = 1;
 507                 }
 508
 509                 # Check if one of the revisions is deleted/suppressed
 510                 $deleted = $suppressed = false;
 511                 $allowed = $this->mNewRev->userCan( RevisionRecord::DELETED_TEXT, $user );
 512
 513                 $revisionTools = [];
 514
 515                 # mOldRev is false if the difference engine is called with a "vague" query for
 516                 # a diff between a version V and its previous version V' AND the version V
 517                 # is the first version of that article. In that case, V' does not exist.
 518                 if ( $this->mOldRev === false ) {
 519                         if ( $this->mNewPage ) {
 520                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 521                         }
 522                         $samePage = true;
 523                         $oldHeader = '';
 524                         // Allow extensions to change the $oldHeader variable
 525                         Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
 526                 } else {
 527                         Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 528
 529                         if ( !$this->mOldPage || !$this->mNewPage ) {
 530                                 // XXX say something to the user?
 531                                 $samePage = false;
 532                         } elseif ( $this->mNewPage->equals( $this->mOldPage ) ) {
 533                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 534                                 $samePage = true;
 535                         } else {
 536                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 537                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 538                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 539                                 $samePage = false;
 540                         }
 541
 542                         $permissionManager = MediaWikiServices::getInstance()->getPermissionManager();
 543
 544                         if ( $samePage && $this->mNewPage && $permissionManager->userCan(
 545                                 'edit', $user, $this->mNewPage, PermissionManager::RIGOR_QUICK
 546                         ) ) {
 547                                 if ( $this->mNewRev->isCurrent() && $permissionManager->userCan(
 548                                         'rollback', $user, $this->mNewPage
 549                                 ) ) {
 550                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 551                                         if ( $rollbackLink ) {
 552                                                 $out->preventClickjacking();
 553                                                 $rollback = "\u{00A0}\u{00A0}\u{00A0}" . $rollbackLink;
 554                                         }
 555                                 }
 556
 557                                 if ( !$this->mOldRev->isDeleted( RevisionRecord::DELETED_TEXT ) &&
 558                                         !$this->mNewRev->isDeleted( RevisionRecord::DELETED_TEXT )
 559                                 ) {
 560                                         $undoLink = Html::element( 'a', [
 561                                                         'href' => $this->mNewPage->getLocalURL( [
 562                                                                 'action' => 'edit',
 563                                                                 'undoafter' => $this->mOldid,
 564                                                                 'undo' => $this->mNewid
 565                                                         ] ),
 566                                                         'title' => Linker::titleAttrib( 'undo' ),
 567                                                 ],
 568                                                 $this->msg( 'editundo' )->text()
 569                                         );
 570                                         $revisionTools['mw-diff-undo'] = $undoLink;
 571                                 }
 572                         }
 573
 574                         # Make "previous revision link"
 575                         if ( $samePage && $this->mOldPage && $this->mOldRev->getPrevious() ) {
 576                                 $prevlink = Linker::linkKnown(
 577                                         $this->mOldPage,
 578                                         $this->msg( 'previousdiff' )->escaped(),
 579                                         [ 'id' => 'differences-prevlink' ],
 580                                         [ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
 581                                 );
 582                         } else {
 583                                 $prevlink = "\u{00A0}";
 584                         }
 585
 586                         if ( $this->mOldRev->isMinor() ) {
 587                                 $oldminor = ChangesList::flag( 'minor' );
 588                         } else {
 589                                 $oldminor = '';
 590                         }
 591
 592                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 593                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 594                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );
 595
 596                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 597                                 '<div id="mw-diff-otitle2">' .
 598                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 599                                 '<div id="mw-diff-otitle3">' . $oldminor .
 600                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 601                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 602                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 603
 604                         // Allow extensions to change the $oldHeader variable
 605                         Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
 606                                 $diffOnly, $ldel, $this->unhide ] );
 607
 608                         if ( $this->mOldRev->isDeleted( RevisionRecord::DELETED_TEXT ) ) {
 609                                 $deleted = true; // old revisions text is hidden
 610                                 if ( $this->mOldRev->isDeleted( RevisionRecord::DELETED_RESTRICTED ) ) {
 611                                         $suppressed = true; // also suppressed
 612                                 }
 613                         }
 614
 615                         # Check if this user can see the revisions
 616                         if ( !$this->mOldRev->userCan( RevisionRecord::DELETED_TEXT, $user ) ) {
 617                                 $allowed = false;
 618                         }
 619                 }
 620
 621                 $out->addJsConfigVars( [
 622                         'wgDiffOldId' => $this->mOldid,
 623                         'wgDiffNewId' => $this->mNewid,
 624                 ] );
 625
 626                 # Make "next revision link"
 627                 # Skip next link on the top revision
 628                 if ( $samePage && $this->mNewPage && !$this->mNewRev->isCurrent() ) {
 629                         $nextlink = Linker::linkKnown(
 630                                 $this->mNewPage,
 631                                 $this->msg( 'nextdiff' )->escaped(),
 632                                 [ 'id' => 'differences-nextlink' ],
 633                                 [ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
 634                         );
 635                 } else {
 636                         $nextlink = "\u{00A0}";
 637                 }
 638
 639                 if ( $this->mNewRev->isMinor() ) {
 640                         $newminor = ChangesList::flag( 'minor' );
 641                 } else {
 642                         $newminor = '';
 643                 }
 644
 645                 # Handle RevisionDelete links...
 646                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 647
 648                 # Allow extensions to define their own revision tools
 649                 Hooks::run( 'DiffRevisionTools',
 650                         [ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
 651                 $formattedRevisionTools = [];
 652                 // Put each one in parentheses (poor man's button)
 653                 foreach ( $revisionTools as $key => $tool ) {
 654                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 655                         $element = Html::rawElement(
 656                                 'span',
 657                                 [ 'class' => $toolClass ],
 658                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 659                         );
 660                         $formattedRevisionTools[] = $element;
 661                 }
 662                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 663                         ' ' . implode( ' ', $formattedRevisionTools );
 664                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );
 665
 666                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 667                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 668                         " $rollback</div>" .
 669                         '<div id="mw-diff-ntitle3">' . $newminor .
 670                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 671                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 672                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 673
 674                 // Allow extensions to change the $newHeader variable
 675                 Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
 676                         $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
 677
 678                 if ( $this->mNewRev->isDeleted( RevisionRecord::DELETED_TEXT ) ) {
 679                         $deleted = true; // new revisions text is hidden
 680                         if ( $this->mNewRev->isDeleted( RevisionRecord::DELETED_RESTRICTED ) ) {
 681                                 $suppressed = true; // also suppressed
 682                         }
 683                 }
 684
 685                 # If the diff cannot be shown due to a deleted revision, then output
 686                 # the diff header and links to unhide (if available)...
 687                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 688                         $this->showDiffStyle();
 689                         $multi = $this->getMultiNotice();
 690                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 691                         if ( !$allowed ) {
 692                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 693                                 # Give explanation for why revision is not visible
 694                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 695                                         [ $msg ] );
 696                         } else {
 697                                 # Give explanation and add a link to view the diff...
 698                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
 699                                 $link = $this->getTitle()->getFullURL( $query );
 700                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 701                                 $out->wrapWikiMsg(
 702                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 703                                         [ $msg, $link ]
 704                                 );
 705                         }
 706                 # Otherwise, output a regular diff...
 707                 } else {
 708                         # Add deletion notice if the user is viewing deleted content
 709                         $notice = '';
 710                         if ( $deleted ) {
 711                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 712                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 713                                         $this->msg( $msg )->parse() .
 714                                         "</div>\n";
 715                         }
 716                         $this->showDiff( $oldHeader, $newHeader, $notice );
 717                         if ( !$diffOnly ) {
 718                                 $this->renderNewRevision();
 719                         }
 720                 }
 721         }
 722
 723         /**
 724          * Build a link to mark a change as patrolled.
 725          *
 726          * Returns empty string if there's either no revision to patrol or the user is not allowed to.
 727          * Side effect: When the patrol link is build, this method will call
 728          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 729          *
 730          * @return string HTML or empty string
 731          */
 732         public function markPatrolledLink() {
 733                 if ( $this->mMarkPatrolledLink === null ) {
 734                         $linkInfo = $this->getMarkPatrolledLinkInfo();
 735                         // If false, there is no patrol link needed/allowed
 736                         if ( !$linkInfo || !$this->mNewPage ) {
 737                                 $this->mMarkPatrolledLink = '';
 738                         } else {
 739                                 $this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
 740                                         Linker::linkKnown(
 741                                                 $this->mNewPage,
 742                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 743                                                 [],
 744                                                 [
 745                                                         'action' => 'markpatrolled',
 746                                                         'rcid' => $linkInfo['rcid'],
 747                                                 ]
 748                                         ) . ']</span>';
 749                                 // Allow extensions to change the markpatrolled link
 750                                 Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
 751                                         &$this->mMarkPatrolledLink, $linkInfo['rcid'] ] );
 752                         }
 753                 }
 754                 return $this->mMarkPatrolledLink;
 755         }
 756
 757         /**
 758          * Returns an array of meta data needed to build a "mark as patrolled" link and
 759          * adds the mediawiki.page.patrol.ajax to the output.
 760          *
 761          * @return array|false An array of meta data for a patrol link (rcid only)
 762          *  or false if no link is needed
 763          */
 764         protected function getMarkPatrolledLinkInfo() {
 765                 $user = $this->getUser();
 766                 $config = $this->getConfig();
 767
 768                 // Prepare a change patrol link, if applicable
 769                 if (
 770                         // Is patrolling enabled and the user allowed to?
 771                         $config->get( 'UseRCPatrol' ) &&
 772                         $this->mNewPage && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 773                         // Only do this if the revision isn't more than 6 hours older
 774                         // than the Max RC age (6h because the RC might not be cleaned out regularly)
 775                         RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 776                 ) {
 777                         // Look for an unpatrolled change corresponding to this diff
 778                         $db = wfGetDB( DB_REPLICA );
 779                         $change = RecentChange::newFromConds(
 780                                 [
 781                                         'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 782                                         'rc_this_oldid' => $this->mNewid,
 783                                         'rc_patrolled' => RecentChange::PRC_UNPATROLLED
 784                                 ],
 785                                 __METHOD__
 786                         );
 787
 788                         if ( $change && !$change->getPerformer()->equals( $user ) ) {
 789                                 $rcid = $change->getAttribute( 'rc_id' );
 790                         } else {
 791                                 // None found or the page has been created by the current user.
 792                                 // If the user could patrol this it already would be patrolled
 793                                 $rcid = 0;
 794                         }
 795
 796                         // Allow extensions to possibly change the rcid here
 797                         // For example the rcid might be set to zero due to the user
 798                         // being the same as the performer of the change but an extension
 799                         // might still want to show it under certain conditions
 800                         Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
 801
 802                         // Build the link
 803                         if ( $rcid ) {
 804                                 $this->getOutput()->preventClickjacking();
 805                                 if ( $user->isAllowed( 'writeapi' ) ) {
 806                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 807                                 }
 808
 809                                 return [
 810                                         'rcid' => $rcid,
 811                                 ];
 812                         }
 813                 }
 814
 815                 // No mark as patrolled link applicable
 816                 return false;
 817         }
 818
 819         /**
 820          * @param Revision $rev
 821          *
 822          * @return string
 823          */
 824         protected function revisionDeleteLink( $rev ) {
 825                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 826                 if ( $link !== '' ) {
 827                         $link = "\u{00A0}\u{00A0}\u{00A0}" . $link . ' ';
 828                 }
 829
 830                 return $link;
 831         }
 832
 833         /**
 834          * Show the new revision of the page.
 835          *
 836          * @note Not supported after calling setContent().
 837          */
 838         public function renderNewRevision() {
 839                 if ( $this->isContentOverridden ) {
 840                         // The code below only works with a Revision object. We could construct a fake revision
 841                         // (here or in setContent), but since this does not seem needed at the moment,
 842                         // we'll just fail for now.
 843                         throw new LogicException(
 844                                 __METHOD__
 845                                 . ' is not supported after calling setContent(). Use setRevisions() instead.'
 846                         );
 847                 }
 848
 849                 $out = $this->getOutput();
 850                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 851                 # Add "current version as of X" title
 852                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 853                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 854                 # Page content may be handled by a hooked call instead...
 855                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 856                         $this->loadNewText();
 857                         if ( !$this->mNewPage ) {
 858                                 // New revision is unsaved; bail out.
 859                                 // TODO in theory rendering the new revision is a meaningful thing to do
 860                                 // even if it's unsaved, but a lot of untangling is required to do it safely.
 861                                 return;
 862                         }
 863
 864                         $out->setRevisionId( $this->mNewid );
 865                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 866                         $out->setArticleFlag( true );
 867
 868                         if ( !Hooks::run( 'ArticleRevisionViewCustom',
 869                                 [ $this->mNewRev->getRevisionRecord(), $this->mNewPage, $out ] )
 870                         ) {
 871                                 // Handled by extension
 872                                 // NOTE: sync with hooks called in Article::view()
 873                         } elseif ( !Hooks::run( 'ArticleContentViewCustom',
 874                                 [ $this->mNewContent, $this->mNewPage, $out ], '1.32' )
 875                         ) {
 876                                 // Handled by extension
 877                                 // NOTE: sync with hooks called in Article::view()
 878                         } else {
 879                                 // Normal page
 880                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 881                                         // If the Title stored in the context is the same as the one
 882                                         // of the new revision, we can use its associated WikiPage
 883                                         // object.
 884                                         $wikiPage = $this->getWikiPage();
 885                                 } else {
 886                                         // Otherwise we need to create our own WikiPage object
 887                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 888                                 }
 889
 890                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 891
 892                                 # WikiPage::getParserOutput() should not return false, but just in case
 893                                 if ( $parserOutput ) {
 894                                         // Allow extensions to change parser output here
 895                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput',
 896                                                 [ $this, $out, $parserOutput, $wikiPage ] )
 897                                         ) {
 898                                                 $out->addParserOutput( $parserOutput, [
 899                                                         'enableSectionEditLinks' => $this->mNewRev->isCurrent()
 900                                                                 && $this->mNewRev->getTitle()->quickUserCan( 'edit', $this->getUser() ),
 901                                                 ] );
 902                                         }
 903                                 }
 904                         }
 905                 }
 906
 907                 // Allow extensions to optionally not show the final patrolled link
 908                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 909                         # Add redundant patrol link on bottom...
 910                         $out->addHTML( $this->markPatrolledLink() );
 911                 }
 912         }
 913
 914         /**
 915          * @param WikiPage $page
 916          * @param Revision $rev
 917          *
 918          * @return ParserOutput|bool False if the revision was not found
 919          */
 920         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 921                 if ( !$rev->getId() ) {
 922                         // WikiPage::getParserOutput wants a revision ID. Passing 0 will incorrectly show
 923                         // the current revision, so fail instead. If need be, WikiPage::getParserOutput
 924                         // could be made to accept a Revision or RevisionRecord instead of the id.
 925                         return false;
 926                 }
 927
 928                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 929                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 930
 931                 return $parserOutput;
 932         }
 933
 934         /**
 935          * Get the diff text, send it to the OutputPage object
 936          * Returns false if the diff could not be generated, otherwise returns true
 937          *
 938          * @param string|bool $otitle Header for old text or false
 939          * @param string|bool $ntitle Header for new text or false
 940          * @param string $notice HTML between diff header and body
 941          *
 942          * @return bool
 943          */
 944         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 945                 // Allow extensions to affect the output here
 946                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 947
 948                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 949                 if ( $diff === false ) {
 950                         $this->showMissingRevision();
 951
 952                         return false;
 953                 } else {
 954                         $this->showDiffStyle();
 955                         $this->getOutput()->addHTML( $diff );
 956
 957                         return true;
 958                 }
 959         }
 960
 961         /**
 962          * Add style sheets for diff display.
 963          */
 964         public function showDiffStyle() {
 965                 if ( !$this->isSlotDiffRenderer ) {
 966                         $this->getOutput()->addModuleStyles( [
 967                                 'mediawiki.interface.helpers.styles',
 968                                 'mediawiki.diff.styles'
 969                         ] );
 970                         foreach ( $this->getSlotDiffRenderers() as $slotDiffRenderer ) {
 971                                 $slotDiffRenderer->addModules( $this->getOutput() );
 972                         }
 973                 }
 974         }
 975
 976         /**
 977          * Get complete diff table, including header
 978          *
 979          * @param string|bool $otitle Header for old text or false
 980          * @param string|bool $ntitle Header for new text or false
 981          * @param string $notice HTML between diff header and body
 982          *
 983          * @return mixed
 984          */
 985         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 986                 $body = $this->getDiffBody();
 987                 if ( $body === false ) {
 988                         return false;
 989                 }
 990
 991                 $multi = $this->getMultiNotice();
 992                 // Display a message when the diff is empty
 993                 if ( $body === '' ) {
 994                         $notice .= '<div class="mw-diff-empty">' .
 995                                 $this->msg( 'diff-empty' )->parse() .
 996                                 "</div>\n";
 997                 }
 998
 999                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
1000         }
1001
1002         /**
1003          * Get the diff table body, without header
1004          *
1005          * @return mixed (string/false)
1006          */
1007         public function getDiffBody() {
1008                 $this->mCacheHit = true;
1009                 // Check if the diff should be hidden from this user
1010                 if ( !$this->isContentOverridden ) {
1011                         if ( !$this->loadRevisionData() ) {
1012                                 return false;
1013                         } elseif ( $this->mOldRev &&
1014                                 !$this->mOldRev->userCan( RevisionRecord::DELETED_TEXT, $this->getUser() )
1015                         ) {
1016                                 return false;
1017                         } elseif ( $this->mNewRev &&
1018                                 !$this->mNewRev->userCan( RevisionRecord::DELETED_TEXT, $this->getUser() )
1019                         ) {
1020                                 return false;
1021                         }
1022                         // Short-circuit
1023                         if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev &&
1024                                 $this->mOldRev->getId() && $this->mOldRev->getId() == $this->mNewRev->getId() )
1025                         ) {
1026                                 if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
1027                                         return '';
1028                                 }
1029                         }
1030                 }
1031
1032                 // Cacheable?
1033                 $key = false;
1034                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1035                 if ( $this->mOldid && $this->mNewid ) {
1036                         // Check if subclass is still using the old way
1037                         // for backwards-compatibility
1038                         $key = $this->getDiffBodyCacheKey();
1039                         if ( $key === null ) {
1040                                 $key = $cache->makeKey( ...$this->getDiffBodyCacheKeyParams() );
1041                         }
1042
1043                         // Try cache
1044                         if ( !$this->mRefreshCache ) {
1045                                 $difftext = $cache->get( $key );
1046                                 if ( is_string( $difftext ) ) {
1047                                         wfIncrStats( 'diff_cache.hit' );
1048                                         $difftext = $this->localiseDiff( $difftext );
1049                                         $difftext .= "\n<!-- diff cache key $key -->\n";
1050
1051                                         return $difftext;
1052                                 }
1053                         } // don't try to load but save the result
1054                 }
1055                 $this->mCacheHit = false;
1056
1057                 // Loadtext is permission safe, this just clears out the diff
1058                 if ( !$this->loadText() ) {
1059                         return false;
1060                 }
1061
1062                 $difftext = '';
1063                 // We've checked for revdelete at the beginning of this method; it's OK to ignore
1064                 // read permissions here.
1065                 $slotContents = $this->getSlotContents();
1066                 foreach ( $this->getSlotDiffRenderers() as $role => $slotDiffRenderer ) {
1067                         $slotDiff = $slotDiffRenderer->getDiff( $slotContents[$role]['old'],
1068                                 $slotContents[$role]['new'] );
1069                         if ( $slotDiff && $role !== SlotRecord::MAIN ) {
1070                                 // FIXME: ask SlotRoleHandler::getSlotNameMessage
1071                                 $slotTitle = $role;
1072                                 $difftext .= $this->getSlotHeader( $slotTitle );
1073                         }
1074                         $difftext .= $slotDiff;
1075                 }
1076
1077                 // Avoid PHP 7.1 warning from passing $this by reference
1078                 $diffEngine = $this;
1079
1080                 // Save to cache for 7 days
1081                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
1082                         wfIncrStats( 'diff_cache.uncacheable' );
1083                 } elseif ( $key !== false && $difftext !== false ) {
1084                         wfIncrStats( 'diff_cache.miss' );
1085                         $cache->set( $key, $difftext, 7 * 86400 );
1086                 } else {
1087                         wfIncrStats( 'diff_cache.uncacheable' );
1088                 }
1089                 // localise line numbers and title attribute text
1090                 if ( $difftext !== false ) {
1091                         $difftext = $this->localiseDiff( $difftext );
1092                 }
1093
1094                 return $difftext;
1095         }
1096
1097         /**
1098          * Get the diff table body for one slot, without header
1099          *
1100          * @param string $role
1101          * @return string|false
1102          */
1103         public function getDiffBodyForRole( $role ) {
1104                 $diffRenderers = $this->getSlotDiffRenderers();
1105                 if ( !isset( $diffRenderers[$role] ) ) {
1106                         return false;
1107                 }
1108
1109                 $slotContents = $this->getSlotContents();
1110                 $slotDiff = $diffRenderers[$role]->getDiff( $slotContents[$role]['old'],
1111                         $slotContents[$role]['new'] );
1112                 if ( !$slotDiff ) {
1113                         return false;
1114                 }
1115
1116                 if ( $role !== SlotRecord::MAIN ) {
1117                         // TODO use human-readable role name at least
1118                         $slotTitle = $role;
1119                         $slotDiff = $this->getSlotHeader( $slotTitle ) . $slotDiff;
1120                 }
1121
1122                 return $this->localiseDiff( $slotDiff );
1123         }
1124
1125         /**
1126          * Get a slot header for inclusion in a diff body (as a table row).
1127          *
1128          * @param string $headerText The text of the header
1129          * @return string
1130          *
1131          */
1132         protected function getSlotHeader( $headerText ) {
1133                 // The old revision is missing on oldid=<first>&diff=prev; only 2 columns in that case.
1134                 $columnCount = $this->mOldRev ? 4 : 2;
1135                 $userLang = $this->getLanguage()->getHtmlCode();
1136                 return Html::rawElement( 'tr', [ 'class' => 'mw-diff-slot-header', 'lang' => $userLang ],
1137                         Html::element( 'th', [ 'colspan' => $columnCount ], $headerText ) );
1138         }
1139
1140         /**
1141          * Returns the cache key for diff body text or content.
1142          *
1143          * @deprecated since 1.31, use getDiffBodyCacheKeyParams() instead
1144          * @since 1.23
1145          *
1146          * @throws MWException
1147          * @return string|null
1148          */
1149         protected function getDiffBodyCacheKey() {
1150                 return null;
1151         }
1152
1153         /**
1154          * Get the cache key parameters
1155          *
1156          * Subclasses can replace the first element in the array to something
1157          * more specific to the type of diff (e.g. "inline-diff"), or append
1158          * if the cache should vary on more things. Overriding entirely should
1159          * be avoided.
1160          *
1161          * @since 1.31
1162          *
1163          * @return array
1164          * @throws MWException
1165          */
1166         protected function getDiffBodyCacheKeyParams() {
1167                 if ( !$this->mOldid || !$this->mNewid ) {
1168                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
1169                 }
1170
1171                 $engine = $this->getEngine();
1172                 $params = [
1173                         'diff',
1174                         $engine,
1175                         self::DIFF_VERSION,
1176                         "old-{$this->mOldid}",
1177                         "rev-{$this->mNewid}"
1178                 ];
1179
1180                 if ( $engine === 'wikidiff2' ) {
1181                         $params[] = phpversion( 'wikidiff2' );
1182                 }
1183
1184                 if ( !$this->isSlotDiffRenderer ) {
1185                         foreach ( $this->getSlotDiffRenderers() as $slotDiffRenderer ) {
1186                                 $params = array_merge( $params, $slotDiffRenderer->getExtraCacheKeys() );
1187                         }
1188                 }
1189
1190                 return $params;
1191         }
1192
1193         /**
1194          * Implements DifferenceEngineSlotDiffRenderer::getExtraCacheKeys(). Only used when
1195          * DifferenceEngine is wrapped in DifferenceEngineSlotDiffRenderer.
1196          * @return array
1197          * @internal for use by DifferenceEngineSlotDiffRenderer only
1198          * @deprecated
1199          */
1200         public function getExtraCacheKeys() {
1201                 // This method is called when the DifferenceEngine is used for a slot diff. We only care
1202                 // about special things, not the revision IDs, which are added to the cache key by the
1203                 // page-level DifferenceEngine, and which might not have a valid value for this object.
1204                 $this->mOldid = 123456789;
1205                 $this->mNewid = 987654321;
1206
1207                 // This will repeat a bunch of unnecessary key fields for each slot. Not nice but harmless.
1208                 $cacheString = $this->getDiffBodyCacheKey();
1209                 if ( $cacheString ) {
1210                         return [ $cacheString ];
1211                 }
1212
1213                 $params = $this->getDiffBodyCacheKeyParams();
1214
1215                 // Try to get rid of the standard keys to keep the cache key human-readable:
1216                 // call the getDiffBodyCacheKeyParams implementation of the base class, and if
1217                 // the child class includes the same keys, drop them.
1218                 // Uses an obscure PHP feature where static calls to non-static methods are allowed
1219                 // as long as we are already in a non-static method of the same class, and the call context
1220                 // ($this) will be inherited.
1221                 // phpcs:ignore Squiz.Classes.SelfMemberReference.NotUsed
1222                 $standardParams = DifferenceEngine::getDiffBodyCacheKeyParams();
1223                 if ( array_slice( $params, 0, count( $standardParams ) ) === $standardParams ) {
1224                         $params = array_slice( $params, count( $standardParams ) );
1225                 }
1226
1227                 return $params;
1228         }
1229
1230         /**
1231          * Generate a diff, no caching.
1232          *
1233          * @since 1.21
1234          *
1235          * @param Content $old Old content
1236          * @param Content $new New content
1237          *
1238          * @throws Exception If old or new content is not an instance of TextContent.
1239          * @return bool|string
1240          *
1241          * @deprecated since 1.32, use a SlotDiffRenderer instead.
1242          */
1243         public function generateContentDiffBody( Content $old, Content $new ) {
1244                 $slotDiffRenderer = $new->getContentHandler()->getSlotDiffRenderer( $this->getContext() );
1245                 if (
1246                         $slotDiffRenderer instanceof DifferenceEngineSlotDiffRenderer
1247                         && $this->isSlotDiffRenderer
1248                 ) {
1249                         // Oops, we are just about to enter an infinite loop (the slot-level DifferenceEngine
1250                         // called a DifferenceEngineSlotDiffRenderer that wraps the same DifferenceEngine class).
1251                         // This will happen when a content model has no custom slot diff renderer, it does have
1252                         // a custom difference engine, but that does not override this method.
1253                         throw new Exception( get_class( $this ) . ': could not maintain backwards compatibility. '
1254                                 . 'Please use a SlotDiffRenderer.' );
1255                 }
1256                 return $slotDiffRenderer->getDiff( $old, $new ) . $this->getDebugString();
1257         }
1258
1259         /**
1260          * Generate a diff, no caching
1261          *
1262          * @param string $otext Old text, must be already segmented
1263          * @param string $ntext New text, must be already segmented
1264          *
1265          * @throws Exception If content handling for text content is configured in a way
1266          *   that makes maintaining B/C hard.
1267          * @return bool|string
1268          *
1269          * @deprecated since 1.32, use a TextSlotDiffRenderer instead.
1270          */
1271         public function generateTextDiffBody( $otext, $ntext ) {
1272                 $slotDiffRenderer = ContentHandler::getForModelID( CONTENT_MODEL_TEXT )
1273                         ->getSlotDiffRenderer( $this->getContext() );
1274                 if ( !( $slotDiffRenderer instanceof TextSlotDiffRenderer ) ) {
1275                         // Someone used the GetSlotDiffRenderer hook to replace the renderer.
1276                         // This is too unlikely to happen to bother handling properly.
1277                         throw new Exception( 'The slot diff renderer for text content should be a '
1278                                 . 'TextSlotDiffRenderer subclass' );
1279                 }
1280                 return $slotDiffRenderer->getTextDiff( $otext, $ntext ) . $this->getDebugString();
1281         }
1282
1283         /**
1284          * Process $wgExternalDiffEngine and get a sane, usable engine
1285          *
1286          * @return bool|string 'wikidiff2', path to an executable, or false
1287          * @internal For use by this class and TextSlotDiffRenderer only.
1288          */
1289         public static function getEngine() {
1290                 global $wgExternalDiffEngine;
1291                 // We use the global here instead of Config because we write to the value,
1292                 // and Config is not mutable.
1293                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
1294                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
1295                         $wgExternalDiffEngine = false;
1296                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
1297                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.32' );
1298                         $wgExternalDiffEngine = false;
1299                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
1300                         // And prevent people from shooting themselves in the foot...
1301                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
1302                         $wgExternalDiffEngine = false;
1303                 }
1304
1305                 if ( is_string( $wgExternalDiffEngine ) && is_executable( $wgExternalDiffEngine ) ) {
1306                         return $wgExternalDiffEngine;
1307                 } elseif ( $wgExternalDiffEngine === false && function_exists( 'wikidiff2_do_diff' ) ) {
1308                         return 'wikidiff2';
1309                 } else {
1310                         // Native PHP
1311                         return false;
1312                 }
1313         }
1314
1315         /**
1316          * Generates diff, to be wrapped internally in a logging/instrumentation
1317          *
1318          * @param string $otext Old text, must be already segmented
1319          * @param string $ntext New text, must be already segmented
1320          *
1321          * @throws Exception If content handling for text content is configured in a way
1322          *   that makes maintaining B/C hard.
1323          * @return bool|string
1324          *
1325          * @deprecated since 1.32, use a TextSlotDiffRenderer instead.
1326          */
1327         protected function textDiff( $otext, $ntext ) {
1328                 $slotDiffRenderer = ContentHandler::getForModelID( CONTENT_MODEL_TEXT )
1329                         ->getSlotDiffRenderer( $this->getContext() );
1330                 if ( !( $slotDiffRenderer instanceof TextSlotDiffRenderer ) ) {
1331                         // Someone used the GetSlotDiffRenderer hook to replace the renderer.
1332                         // This is too unlikely to happen to bother handling properly.
1333                         throw new Exception( 'The slot diff renderer for text content should be a '
1334                                 . 'TextSlotDiffRenderer subclass' );
1335                 }
1336                 return $slotDiffRenderer->getTextDiff( $otext, $ntext ) . $this->getDebugString();
1337         }
1338
1339         /**
1340          * Generate a debug comment indicating diff generating time,
1341          * server node, and generator backend.
1342          *
1343          * @param string $generator : What diff engine was used
1344          *
1345          * @return string
1346          */
1347         protected function debug( $generator = "internal" ) {
1348                 if ( !$this->enableDebugComment ) {
1349                         return '';
1350                 }
1351                 $data = [ $generator ];
1352                 if ( $this->getConfig()->get( 'ShowHostnames' ) ) {
1353                         $data[] = wfHostname();
1354                 }
1355                 $data[] = wfTimestamp( TS_DB );
1356
1357                 return "<!-- diff generator: " .
1358                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1359                         " -->\n";
1360         }
1361
1362         private function getDebugString() {
1363                 $engine = self::getEngine();
1364                 if ( $engine === 'wikidiff2' ) {
1365                         return $this->debug( 'wikidiff2' );
1366                 } elseif ( $engine === false ) {
1367                         return $this->debug( 'native PHP' );
1368                 } else {
1369                         return $this->debug( "external $engine" );
1370                 }
1371         }
1372
1373         /**
1374          * Localise diff output
1375          *
1376          * @param string $text
1377          * @return string
1378          */
1379         private function localiseDiff( $text ) {
1380                 $text = $this->localiseLineNumbers( $text );
1381                 if ( $this->getEngine() === 'wikidiff2' &&
1382                         version_compare( phpversion( 'wikidiff2' ), '1.5.1', '>=' )
1383                 ) {
1384                         $text = $this->addLocalisedTitleTooltips( $text );
1385                 }
1386                 return $text;
1387         }
1388
1389         /**
1390          * Replace line numbers with the text in the user's language
1391          *
1392          * @param string $text
1393          *
1394          * @return mixed
1395          */
1396         public function localiseLineNumbers( $text ) {
1397                 return preg_replace_callback(
1398                         '/<!--LINE (\d+)-->/',
1399                         [ $this, 'localiseLineNumbersCb' ],
1400                         $text
1401                 );
1402         }
1403
1404         public function localiseLineNumbersCb( $matches ) {
1405                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1406                         return '';
1407                 }
1408
1409                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1410         }
1411
1412         /**
1413          * Add title attributes for tooltips on moved paragraph indicators
1414          *
1415          * @param string $text
1416          * @return string
1417          */
1418         private function addLocalisedTitleTooltips( $text ) {
1419                 return preg_replace_callback(
1420                         '/class="mw-diff-movedpara-(left|right)"/',
1421                         [ $this, 'addLocalisedTitleTooltipsCb' ],
1422                         $text
1423                 );
1424         }
1425
1426         /**
1427          * @param array $matches
1428          * @return string
1429          */
1430         private function addLocalisedTitleTooltipsCb( array $matches ) {
1431                 $key = $matches[1] === 'right' ?
1432                         'diff-paragraph-moved-toold' :
1433                         'diff-paragraph-moved-tonew';
1434                 return $matches[0] . ' title="' . $this->msg( $key )->escaped() . '"';
1435         }
1436
1437         /**
1438          * If there are revisions between the ones being compared, return a note saying so.
1439          *
1440          * @return string
1441          */
1442         public function getMultiNotice() {
1443                 // The notice only make sense if we are diffing two saved revisions of the same page.
1444                 if (
1445                         !$this->mOldRev || !$this->mNewRev
1446                         || !$this->mOldPage || !$this->mNewPage
1447                         || !$this->mOldPage->equals( $this->mNewPage )
1448                 ) {
1449                         return '';
1450                 }
1451
1452                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1453                         $oldRev = $this->mNewRev; // flip
1454                         $newRev = $this->mOldRev; // flip
1455                 } else { // normal case
1456                         $oldRev = $this->mOldRev;
1457                         $newRev = $this->mNewRev;
1458                 }
1459
1460                 // Sanity: don't show the notice if too many rows must be scanned
1461                 // @todo show some special message for that case
1462                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1463                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1464                         $limit = 100; // use diff-multi-manyusers if too many users
1465                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1466                         $numUsers = count( $users );
1467
1468                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( RevisionRecord::RAW ) ) {
1469                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1470                         }
1471
1472                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1473                 }
1474
1475                 return '';
1476         }
1477
1478         /**
1479          * Get a notice about how many intermediate edits and users there are
1480          *
1481          * @param int $numEdits
1482          * @param int $numUsers
1483          * @param int $limit
1484          *
1485          * @return string
1486          */
1487         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1488                 if ( $numUsers === 0 ) {
1489                         $msg = 'diff-multi-sameuser';
1490                 } elseif ( $numUsers > $limit ) {
1491                         $msg = 'diff-multi-manyusers';
1492                         $numUsers = $limit;
1493                 } else {
1494                         $msg = 'diff-multi-otherusers';
1495                 }
1496
1497                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1498         }
1499
1500         /**
1501          * Get a header for a specified revision.
1502          *
1503          * @param Revision $rev
1504          * @param string $complete 'complete' to get the header wrapped depending
1505          *        the visibility of the revision and a link to edit the page.
1506          *
1507          * @return string HTML fragment
1508          */
1509         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1510                 $lang = $this->getLanguage();
1511                 $user = $this->getUser();
1512                 $revtimestamp = $rev->getTimestamp();
1513                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1514                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1515                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1516
1517                 $header = $this->msg(
1518                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1519                         $timestamp,
1520                         $dateofrev,
1521                         $timeofrev
1522                 )->escaped();
1523
1524                 if ( $complete !== 'complete' ) {
1525                         return $header;
1526                 }
1527
1528                 $title = $rev->getTitle();
1529
1530                 $header = Linker::linkKnown( $title, $header, [],
1531                         [ 'oldid' => $rev->getId() ] );
1532
1533                 if ( $rev->userCan( RevisionRecord::DELETED_TEXT, $user ) ) {
1534                         $editQuery = [ 'action' => 'edit' ];
1535                         if ( !$rev->isCurrent() ) {
1536                                 $editQuery['oldid'] = $rev->getId();
1537                         }
1538
1539                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1540                         $msg = $this->msg( $key )->escaped();
1541                         $editLink = $this->msg( 'parentheses' )->rawParams(
1542                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1543                         $header .= ' ' . Html::rawElement(
1544                                 'span',
1545                                 [ 'class' => 'mw-diff-edit' ],
1546                                 $editLink
1547                         );
1548                         if ( $rev->isDeleted( RevisionRecord::DELETED_TEXT ) ) {
1549                                 $header = Html::rawElement(
1550                                         'span',
1551                                         [ 'class' => 'history-deleted' ],
1552                                         $header
1553                                 );
1554                         }
1555                 } else {
1556                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1557                 }
1558
1559                 return $header;
1560         }
1561
1562         /**
1563          * Add the header to a diff body
1564          *
1565          * @param string $diff Diff body
1566          * @param string $otitle Old revision header
1567          * @param string $ntitle New revision header
1568          * @param string $multi Notice telling user that there are intermediate
1569          *   revisions between the ones being compared
1570          * @param string $notice Other notices, e.g. that user is viewing deleted content
1571          *
1572          * @return string
1573          */
1574         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1575                 // shared.css sets diff in interface language/dir, but the actual content
1576                 // is often in a different language, mostly the page content language/dir
1577                 $header = Html::openElement( 'table', [
1578                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1579                         'data-mw' => 'interface',
1580                 ] );
1581                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1582
1583                 if ( !$diff && !$otitle ) {
1584                         $header .= "
1585                         <tr class=\"diff-title\" lang=\"{$userLang}\">
1586                         <td class=\"diff-ntitle\">{$ntitle}</td>
1587                         </tr>";
1588                         $multiColspan = 1;
1589                 } else {
1590                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1591                                 $header .= "
1592                                 <col class=\"diff-marker\" />
1593                                 <col class=\"diff-content\" />
1594                                 <col class=\"diff-marker\" />
1595                                 <col class=\"diff-content\" />";
1596                                 $colspan = 2;
1597                                 $multiColspan = 4;
1598                         } else {
1599                                 $colspan = 1;
1600                                 $multiColspan = 2;
1601                         }
1602                         if ( $otitle || $ntitle ) {
1603                                 $header .= "
1604                                 <tr class=\"diff-title\" lang=\"{$userLang}\">
1605                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1606                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1607                                 </tr>";
1608                         }
1609                 }
1610
1611                 if ( $multi != '' ) {
1612                         $header .= "<tr><td colspan=\"{$multiColspan}\" " .
1613                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1614                 }
1615                 if ( $notice != '' ) {
1616                         $header .= "<tr><td colspan=\"{$multiColspan}\" " .
1617                                 "class=\"diff-notice\" lang=\"{$userLang}\">{$notice}</td></tr>";
1618                 }
1619
1620                 return $header . $diff . "</table>";
1621         }
1622
1623         /**
1624          * Use specified text instead of loading from the database
1625          * @param Content $oldContent
1626          * @param Content $newContent
1627          * @since 1.21
1628          * @deprecated since 1.32, use setRevisions or ContentHandler::getSlotDiffRenderer.
1629          */
1630         public function setContent( Content $oldContent, Content $newContent ) {
1631                 $this->mOldContent = $oldContent;
1632                 $this->mNewContent = $newContent;
1633
1634                 $this->mTextLoaded = 2;
1635                 $this->mRevisionsLoaded = true;
1636                 $this->isContentOverridden = true;
1637                 $this->slotDiffRenderers = null;
1638         }
1639
1640         /**
1641          * Use specified text instead of loading from the database.
1642          * @param RevisionRecord|null $oldRevision
1643          * @param RevisionRecord $newRevision
1644          */
1645         public function setRevisions(
1646                 RevisionRecord $oldRevision = null, RevisionRecord $newRevision
1647         ) {
1648                 if ( $oldRevision ) {
1649                         $this->mOldRev = new Revision( $oldRevision );
1650                         $this->mOldid = $oldRevision->getId();
1651                         $this->mOldPage = Title::newFromLinkTarget( $oldRevision->getPageAsLinkTarget() );
1652                         // This method is meant for edit diffs and such so there is no reason to provide a
1653                         // revision that's not readable to the user, but check it just in case.
1654                         $this->mOldContent = $oldRevision->getContent( SlotRecord::MAIN,
1655                                 RevisionRecord::FOR_THIS_USER, $this->getUser() );
1656                 } else {
1657                         $this->mOldPage = null;
1658                         $this->mOldRev = $this->mOldid = false;
1659                 }
1660                 $this->mNewRev = new Revision( $newRevision );
1661                 $this->mNewid = $newRevision->getId();
1662                 $this->mNewPage = Title::newFromLinkTarget( $newRevision->getPageAsLinkTarget() );
1663                 $this->mNewContent = $newRevision->getContent( SlotRecord::MAIN,
1664                         RevisionRecord::FOR_THIS_USER, $this->getUser() );
1665
1666                 $this->mRevisionsIdsLoaded = $this->mRevisionsLoaded = true;
1667                 $this->mTextLoaded = $oldRevision ? 2 : 1;
1668                 $this->isContentOverridden = false;
1669                 $this->slotDiffRenderers = null;
1670         }
1671
1672         /**
1673          * Set the language in which the diff text is written
1674          *
1675          * @param Language $lang
1676          * @since 1.19
1677          */
1678         public function setTextLanguage( Language $lang ) {
1679                 $this->mDiffLang = $lang;
1680         }
1681
1682         /**
1683          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1684          * to a pair of actual integers representing revision ids.
1685          *
1686          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1687          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1688          *
1689          * @return array List of two revision ids, older first, later second.
1690          *     Zero signifies invalid argument passed.
1691          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1692          */
1693         public function mapDiffPrevNext( $old, $new ) {
1694                 if ( $new === 'prev' ) {
1695                         // Show diff between revision $old and the previous one. Get previous one from DB.
1696                         $newid = intval( $old );
1697                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1698                 } elseif ( $new === 'next' ) {
1699                         // Show diff between revision $old and the next one. Get next one from DB.
1700                         $oldid = intval( $old );
1701                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1702                 } else {
1703                         $oldid = intval( $old );
1704                         $newid = intval( $new );
1705                 }
1706
1707                 return [ $oldid, $newid ];
1708         }
1709
1710         /**
1711          * Load revision IDs
1712          */
1713         private function loadRevisionIds() {
1714                 if ( $this->mRevisionsIdsLoaded ) {
1715                         return;
1716                 }
1717
1718                 $this->mRevisionsIdsLoaded = true;
1719
1720                 $old = $this->mOldid;
1721                 $new = $this->mNewid;
1722
1723                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1724                 if ( $new === 'next' && $this->mNewid === false ) {
1725                         # if no result, NewId points to the newest old revision. The only newer
1726                         # revision is cur, which is "0".
1727                         $this->mNewid = 0;
1728                 }
1729
1730                 Hooks::run(
1731                         'NewDifferenceEngine',
1732                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1733                 );
1734         }
1735
1736         /**
1737          * Load revision metadata for the specified revisions. If newid is 0, then compare
1738          * the old revision in oldid to the current revision of the current page (as defined
1739          * by the request context); if oldid is 0, then compare the revision in newid to the
1740          * immediately previous one.
1741          *
1742          * If oldid is false, leave the corresponding revision object set to false. This can
1743          * happen with 'diff=prev' pointing to a non-existent revision, and is also used directly
1744          * by the API.
1745          *
1746          * @return bool Whether both revisions were loaded successfully. Setting mOldRev
1747          *   to false counts as successful loading.
1748          */
1749         public function loadRevisionData() {
1750                 if ( $this->mRevisionsLoaded ) {
1751                         return $this->isContentOverridden || ( $this->mOldRev !== null && $this->mNewRev !== null );
1752                 }
1753
1754                 // Whether it succeeds or fails, we don't want to try again
1755                 $this->mRevisionsLoaded = true;
1756
1757                 $this->loadRevisionIds();
1758
1759                 // Load the new revision object
1760                 if ( $this->mNewid ) {
1761                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1762                 } else {
1763                         $this->mNewRev = Revision::newFromTitle(
1764                                 $this->getTitle(),
1765                                 false,
1766                                 Revision::READ_NORMAL
1767                         );
1768                 }
1769
1770                 if ( !$this->mNewRev instanceof Revision ) {
1771                         return false;
1772                 }
1773
1774                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1775                 $this->mNewid = $this->mNewRev->getId();
1776                 if ( $this->mNewid ) {
1777                         $this->mNewPage = $this->mNewRev->getTitle();
1778                 } else {
1779                         $this->mNewPage = null;
1780                 }
1781
1782                 // Load the old revision object
1783                 $this->mOldRev = false;
1784                 if ( $this->mOldid ) {
1785                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1786                 } elseif ( $this->mOldid === 0 ) {
1787                         $rev = $this->mNewRev->getPrevious();
1788                         if ( $rev ) {
1789                                 $this->mOldid = $rev->getId();
1790                                 $this->mOldRev = $rev;
1791                         } else {
1792                                 // No previous revision; mark to show as first-version only.
1793                                 $this->mOldid = false;
1794                                 $this->mOldRev = false;
1795                         }
1796                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1797
1798                 if ( is_null( $this->mOldRev ) ) {
1799                         return false;
1800                 }
1801
1802                 if ( $this->mOldRev && $this->mOldRev->getId() ) {
1803                         $this->mOldPage = $this->mOldRev->getTitle();
1804                 } else {
1805                         $this->mOldPage = null;
1806                 }
1807
1808                 // Load tags information for both revisions
1809                 $dbr = wfGetDB( DB_REPLICA );
1810                 $changeTagDefStore = MediaWikiServices::getInstance()->getChangeTagDefStore();
1811                 if ( $this->mOldid !== false ) {
1812                         $tagIds = $dbr->selectFieldValues(
1813                                 'change_tag',
1814                                 'ct_tag_id',
1815                                 [ 'ct_rev_id' => $this->mOldid ],
1816                                 __METHOD__
1817                         );
1818                         $tags = [];
1819                         foreach ( $tagIds as $tagId ) {
1820                                 try {
1821                                         $tags[] = $changeTagDefStore->getName( (int)$tagId );
1822                                 } catch ( NameTableAccessException $exception ) {
1823                                         continue;
1824                                 }
1825                         }
1826                         $this->mOldTags = implode( ',', $tags );
1827                 } else {
1828                         $this->mOldTags = false;
1829                 }
1830
1831                 $tagIds = $dbr->selectFieldValues(
1832                         'change_tag',
1833                         'ct_tag_id',
1834                         [ 'ct_rev_id' => $this->mNewid ],
1835                         __METHOD__
1836                 );
1837                 $tags = [];
1838                 foreach ( $tagIds as $tagId ) {
1839                         try {
1840                                 $tags[] = $changeTagDefStore->getName( (int)$tagId );
1841                         } catch ( NameTableAccessException $exception ) {
1842                                 continue;
1843                         }
1844                 }
1845                 $this->mNewTags = implode( ',', $tags );
1846
1847                 return true;
1848         }
1849
1850         /**
1851          * Load the text of the revisions, as well as revision data.
1852          * When the old revision is missing (mOldRev is false), loading mOldContent is not attempted.
1853          *
1854          * @return bool Whether the content of both revisions could be loaded successfully.
1855          *   (When mOldRev is false, that still counts as a success.)
1856          *
1857          */
1858         public function loadText() {
1859                 if ( $this->mTextLoaded == 2 ) {
1860                         return $this->loadRevisionData() && ( $this->mOldRev === false || $this->mOldContent )
1861                                 && $this->mNewContent;
1862                 }
1863
1864                 // Whether it succeeds or fails, we don't want to try again
1865                 $this->mTextLoaded = 2;
1866
1867                 if ( !$this->loadRevisionData() ) {
1868                         return false;
1869                 }
1870
1871                 if ( $this->mOldRev ) {
1872                         $this->mOldContent = $this->mOldRev->getContent(
1873                                 RevisionRecord::FOR_THIS_USER, $this->getUser()
1874                         );
1875                         if ( $this->mOldContent === null ) {
1876                                 return false;
1877                         }
1878                 }
1879
1880                 $this->mNewContent = $this->mNewRev->getContent(
1881                         RevisionRecord::FOR_THIS_USER, $this->getUser()
1882                 );
1883                 Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1884                 if ( $this->mNewContent === null ) {
1885                         return false;
1886                 }
1887
1888                 return true;
1889         }
1890
1891         /**
1892          * Load the text of the new revision, not the old one
1893          *
1894          * @return bool Whether the content of the new revision could be loaded successfully.
1895          */
1896         public function loadNewText() {
1897                 if ( $this->mTextLoaded >= 1 ) {
1898                         return $this->loadRevisionData();
1899                 }
1900
1901                 $this->mTextLoaded = 1;
1902
1903                 if ( !$this->loadRevisionData() ) {
1904                         return false;
1905                 }
1906
1907                 $this->mNewContent = $this->mNewRev->getContent(
1908                         RevisionRecord::FOR_THIS_USER, $this->getUser()
1909                 );
1910
1911                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1912
1913                 return true;
1914         }
1915
1916 }