includes/changetags/ChangeTags.php

   1 <?php
   2 /**
   3  * Recent changes tagging.
   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 Change tagging
  22  */
  23
  24 class ChangeTags {
  25         /**
  26          * Can't delete tags with more than this many uses. Similar in intent to
  27          * the bigdelete user right
  28          * @todo Use the job queue for tag deletion to avoid this restriction
  29          */
  30         const MAX_DELETE_USES = 5000;
  31
  32         /**
  33          * @var string[]
  34          */
  35         private static $coreTags = [ 'mw-contentmodelchange' ];
  36
  37         /**
  38          * Creates HTML for the given tags
  39          *
  40          * @param string $tags Comma-separated list of tags
  41          * @param string $page A label for the type of action which is being displayed,
  42          *   for example: 'history', 'contributions' or 'newpages'
  43          * @param IContextSource|null $context
  44          * @note Even though it takes null as a valid argument, an IContextSource is preferred
  45          *       in a new code, as the null value is subject to change in the future
  46          * @return array Array with two items: (html, classes)
  47          *   - html: String: HTML for displaying the tags (empty string when param $tags is empty)
  48          *   - classes: Array of strings: CSS classes used in the generated html, one class for each tag
  49          */
  50         public static function formatSummaryRow( $tags, $page, IContextSource $context = null ) {
  51                 if ( !$tags ) {
  52                         return [ '', [] ];
  53                 }
  54                 if ( !$context ) {
  55                         $context = RequestContext::getMain();
  56                 }
  57
  58                 $classes = [];
  59
  60                 $tags = explode( ',', $tags );
  61                 $displayTags = [];
  62                 foreach ( $tags as $tag ) {
  63                         if ( !$tag ) {
  64                                 continue;
  65                         }
  66                         $description = self::tagDescription( $tag );
  67                         if ( $description === false ) {
  68                                 continue;
  69                         }
  70                         $displayTags[] = Xml::tags(
  71                                 'span',
  72                                 [ 'class' => 'mw-tag-marker ' .
  73                                                                 Sanitizer::escapeClass( "mw-tag-marker-$tag" ) ],
  74                                 $description
  75                         );
  76                         $classes[] = Sanitizer::escapeClass( "mw-tag-$tag" );
  77                 }
  78
  79                 if ( !$displayTags ) {
  80                         return [ '', [] ];
  81                 }
  82
  83                 $markers = $context->msg( 'tag-list-wrapper' )
  84                         ->numParams( count( $displayTags ) )
  85                         ->rawParams( $context->getLanguage()->commaList( $displayTags ) )
  86                         ->parse();
  87                 $markers = Xml::tags( 'span', [ 'class' => 'mw-tag-markers' ], $markers );
  88
  89                 return [ $markers, $classes ];
  90         }
  91
  92         /**
  93          * Get a short description for a tag.
  94          *
  95          * Checks if message key "mediawiki:tag-$tag" exists. If it does not,
  96          * returns the HTML-escaped tag name. Uses the message if the message
  97          * exists, provided it is not disabled. If the message is disabled,
  98          * we consider the tag hidden, and return false.
  99          *
 100          * @param string $tag Tag
 101          * @return string|bool Tag description or false if tag is to be hidden.
 102          * @since 1.25 Returns false if tag is to be hidden.
 103          */
 104         public static function tagDescription( $tag ) {
 105                 $msg = wfMessage( "tag-$tag" );
 106                 if ( !$msg->exists() ) {
 107                         // No such message, so return the HTML-escaped tag name.
 108                         return htmlspecialchars( $tag );
 109                 }
 110                 if ( $msg->isDisabled() ) {
 111                         // The message exists but is disabled, hide the tag.
 112                         return false;
 113                 }
 114
 115                 // Message exists and isn't disabled, use it.
 116                 return $msg->parse();
 117         }
 118
 119         /**
 120          * Add tags to a change given its rc_id, rev_id and/or log_id
 121          *
 122          * @param string|string[] $tags Tags to add to the change
 123          * @param int|null $rc_id The rc_id of the change to add the tags to
 124          * @param int|null $rev_id The rev_id of the change to add the tags to
 125          * @param int|null $log_id The log_id of the change to add the tags to
 126          * @param string $params Params to put in the ct_params field of table 'change_tag'
 127          *
 128          * @throws MWException
 129          * @return bool False if no changes are made, otherwise true
 130          */
 131         public static function addTags( $tags, $rc_id = null, $rev_id = null,
 132                 $log_id = null, $params = null
 133         ) {
 134                 $result = self::updateTags( $tags, null, $rc_id, $rev_id, $log_id, $params );
 135                 return (bool)$result[0];
 136         }
 137
 138         /**
 139          * Add and remove tags to/from a change given its rc_id, rev_id and/or log_id,
 140          * without verifying that the tags exist or are valid. If a tag is present in
 141          * both $tagsToAdd and $tagsToRemove, it will be removed.
 142          *
 143          * This function should only be used by extensions to manipulate tags they
 144          * have registered using the ListDefinedTags hook. When dealing with user
 145          * input, call updateTagsWithChecks() instead.
 146          *
 147          * @param string|array|null $tagsToAdd Tags to add to the change
 148          * @param string|array|null $tagsToRemove Tags to remove from the change
 149          * @param int|null &$rc_id The rc_id of the change to add the tags to.
 150          * Pass a variable whose value is null if the rc_id is not relevant or unknown.
 151          * @param int|null &$rev_id The rev_id of the change to add the tags to.
 152          * Pass a variable whose value is null if the rev_id is not relevant or unknown.
 153          * @param int|null &$log_id The log_id of the change to add the tags to.
 154          * Pass a variable whose value is null if the log_id is not relevant or unknown.
 155          * @param string $params Params to put in the ct_params field of table
 156          * 'change_tag' when adding tags
 157          *
 158          * @throws MWException When $rc_id, $rev_id and $log_id are all null
 159          * @return array Index 0 is an array of tags actually added, index 1 is an
 160          * array of tags actually removed, index 2 is an array of tags present on the
 161          * revision or log entry before any changes were made
 162          *
 163          * @since 1.25
 164          */
 165         public static function updateTags(
 166                 $tagsToAdd, $tagsToRemove,
 167                 &$rc_id = null, &$rev_id = null, &$log_id = null, $params = null
 168         ) {
 169
 170                 $tagsToAdd = array_filter( (array)$tagsToAdd ); // Make sure we're submitting all tags...
 171                 $tagsToRemove = array_filter( (array)$tagsToRemove );
 172
 173                 if ( !$rc_id && !$rev_id && !$log_id ) {
 174                         throw new MWException( 'At least one of: RCID, revision ID, and log ID MUST be ' .
 175                                 'specified when adding or removing a tag from a change!' );
 176                 }
 177
 178                 $dbw = wfGetDB( DB_MASTER );
 179
 180                 // Might as well look for rcids and so on.
 181                 if ( !$rc_id ) {
 182                         // Info might be out of date, somewhat fractionally, on replica DB.
 183                         // LogEntry/LogPage and WikiPage match rev/log/rc timestamps,
 184                         // so use that relation to avoid full table scans.
 185                         if ( $log_id ) {
 186                                 $rc_id = $dbw->selectField(
 187                                         [ 'logging', 'recentchanges' ],
 188                                         'rc_id',
 189                                         [
 190                                                 'log_id' => $log_id,
 191                                                 'rc_timestamp = log_timestamp',
 192                                                 'rc_logid = log_id'
 193                                         ],
 194                                         __METHOD__
 195                                 );
 196                         } elseif ( $rev_id ) {
 197                                 $rc_id = $dbw->selectField(
 198                                         [ 'revision', 'recentchanges' ],
 199                                         'rc_id',
 200                                         [
 201                                                 'rev_id' => $rev_id,
 202                                                 'rc_timestamp = rev_timestamp',
 203                                                 'rc_this_oldid = rev_id'
 204                                         ],
 205                                         __METHOD__
 206                                 );
 207                         }
 208                 } elseif ( !$log_id && !$rev_id ) {
 209                         // Info might be out of date, somewhat fractionally, on replica DB.
 210                         $log_id = $dbw->selectField(
 211                                 'recentchanges',
 212                                 'rc_logid',
 213                                 [ 'rc_id' => $rc_id ],
 214                                 __METHOD__
 215                         );
 216                         $rev_id = $dbw->selectField(
 217                                 'recentchanges',
 218                                 'rc_this_oldid',
 219                                 [ 'rc_id' => $rc_id ],
 220                                 __METHOD__
 221                         );
 222                 }
 223
 224                 if ( $log_id && !$rev_id ) {
 225                         $rev_id = $dbw->selectField(
 226                                 'log_search',
 227                                 'ls_value',
 228                                 [ 'ls_field' => 'associated_rev_id', 'ls_log_id' => $log_id ],
 229                                 __METHOD__
 230                         );
 231                 } elseif ( !$log_id && $rev_id ) {
 232                         $log_id = $dbw->selectField(
 233                                 'log_search',
 234                                 'ls_log_id',
 235                                 [ 'ls_field' => 'associated_rev_id', 'ls_value' => $rev_id ],
 236                                 __METHOD__
 237                         );
 238                 }
 239
 240                 // update the tag_summary row
 241                 $prevTags = [];
 242                 if ( !self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $rc_id, $rev_id,
 243                         $log_id, $prevTags ) ) {
 244
 245                         // nothing to do
 246                         return [ [], [], $prevTags ];
 247                 }
 248
 249                 // insert a row into change_tag for each new tag
 250                 if ( count( $tagsToAdd ) ) {
 251                         $tagsRows = [];
 252                         foreach ( $tagsToAdd as $tag ) {
 253                                 // Filter so we don't insert NULLs as zero accidentally.
 254                                 // Keep in mind that $rc_id === null means "I don't care/know about the
 255                                 // rc_id, just delete $tag on this revision/log entry". It doesn't
 256                                 // mean "only delete tags on this revision/log WHERE rc_id IS NULL".
 257                                 $tagsRows[] = array_filter(
 258                                         [
 259                                                 'ct_tag' => $tag,
 260                                                 'ct_rc_id' => $rc_id,
 261                                                 'ct_log_id' => $log_id,
 262                                                 'ct_rev_id' => $rev_id,
 263                                                 'ct_params' => $params
 264                                         ]
 265                                 );
 266                         }
 267
 268                         $dbw->insert( 'change_tag', $tagsRows, __METHOD__, [ 'IGNORE' ] );
 269                 }
 270
 271                 // delete from change_tag
 272                 if ( count( $tagsToRemove ) ) {
 273                         foreach ( $tagsToRemove as $tag ) {
 274                                 $conds = array_filter(
 275                                         [
 276                                                 'ct_tag' => $tag,
 277                                                 'ct_rc_id' => $rc_id,
 278                                                 'ct_log_id' => $log_id,
 279                                                 'ct_rev_id' => $rev_id
 280                                         ]
 281                                 );
 282                                 $dbw->delete( 'change_tag', $conds, __METHOD__ );
 283                         }
 284                 }
 285
 286                 self::purgeTagUsageCache();
 287                 return [ $tagsToAdd, $tagsToRemove, $prevTags ];
 288         }
 289
 290         /**
 291          * Adds or removes a given set of tags to/from the relevant row of the
 292          * tag_summary table. Modifies the tagsToAdd and tagsToRemove arrays to
 293          * reflect the tags that were actually added and/or removed.
 294          *
 295          * @param array &$tagsToAdd
 296          * @param array &$tagsToRemove If a tag is present in both $tagsToAdd and
 297          * $tagsToRemove, it will be removed
 298          * @param int|null $rc_id Null if not known or not applicable
 299          * @param int|null $rev_id Null if not known or not applicable
 300          * @param int|null $log_id Null if not known or not applicable
 301          * @param array &$prevTags Optionally outputs a list of the tags that were
 302          * in the tag_summary row to begin with
 303          * @return bool True if any modifications were made, otherwise false
 304          * @since 1.25
 305          */
 306         protected static function updateTagSummaryRow( &$tagsToAdd, &$tagsToRemove,
 307                 $rc_id, $rev_id, $log_id, &$prevTags = [] ) {
 308
 309                 $dbw = wfGetDB( DB_MASTER );
 310
 311                 $tsConds = array_filter( [
 312                         'ts_rc_id' => $rc_id,
 313                         'ts_rev_id' => $rev_id,
 314                         'ts_log_id' => $log_id
 315                 ] );
 316
 317                 // Can't both add and remove a tag at the same time...
 318                 $tagsToAdd = array_diff( $tagsToAdd, $tagsToRemove );
 319
 320                 // Update the summary row.
 321                 // $prevTags can be out of date on replica DBs, especially when addTags is called consecutively,
 322                 // causing loss of tags added recently in tag_summary table.
 323                 $prevTags = $dbw->selectField( 'tag_summary', 'ts_tags', $tsConds, __METHOD__ );
 324                 $prevTags = $prevTags ? $prevTags : '';
 325                 $prevTags = array_filter( explode( ',', $prevTags ) );
 326
 327                 // add tags
 328                 $tagsToAdd = array_values( array_diff( $tagsToAdd, $prevTags ) );
 329                 $newTags = array_unique( array_merge( $prevTags, $tagsToAdd ) );
 330
 331                 // remove tags
 332                 $tagsToRemove = array_values( array_intersect( $tagsToRemove, $newTags ) );
 333                 $newTags = array_values( array_diff( $newTags, $tagsToRemove ) );
 334
 335                 sort( $prevTags );
 336                 sort( $newTags );
 337                 if ( $prevTags == $newTags ) {
 338                         // No change.
 339                         return false;
 340                 }
 341
 342                 if ( !$newTags ) {
 343                         // no tags left, so delete the row altogether
 344                         $dbw->delete( 'tag_summary', $tsConds, __METHOD__ );
 345                 } else {
 346                         $dbw->replace( 'tag_summary',
 347                                 [ 'ts_rev_id', 'ts_rc_id', 'ts_log_id' ],
 348                                 array_filter( array_merge( $tsConds, [ 'ts_tags' => implode( ',', $newTags ) ] ) ),
 349                                 __METHOD__
 350                         );
 351                 }
 352
 353                 return true;
 354         }
 355
 356         /**
 357          * Helper function to generate a fatal status with a 'not-allowed' type error.
 358          *
 359          * @param string $msgOne Message key to use in the case of one tag
 360          * @param string $msgMulti Message key to use in the case of more than one tag
 361          * @param array $tags Restricted tags (passed as $1 into the message, count of
 362          * $tags passed as $2)
 363          * @return Status
 364          * @since 1.25
 365          */
 366         protected static function restrictedTagError( $msgOne, $msgMulti, $tags ) {
 367                 $lang = RequestContext::getMain()->getLanguage();
 368                 $count = count( $tags );
 369                 return Status::newFatal( ( $count > 1 ) ? $msgMulti : $msgOne,
 370                         $lang->commaList( $tags ), $count );
 371         }
 372
 373         /**
 374          * Is it OK to allow the user to apply all the specified tags at the same time
 375          * as they edit/make the change?
 376          *
 377          * @param array $tags Tags that you are interested in applying
 378          * @param User|null $user User whose permission you wish to check, or null if
 379          * you don't care (e.g. maintenance scripts)
 380          * @return Status
 381          * @since 1.25
 382          */
 383         public static function canAddTagsAccompanyingChange( array $tags,
 384                 User $user = null ) {
 385
 386                 if ( !is_null( $user ) ) {
 387                         if ( !$user->isAllowed( 'applychangetags' ) ) {
 388                                 return Status::newFatal( 'tags-apply-no-permission' );
 389                         } elseif ( $user->isBlocked() ) {
 390                                 return Status::newFatal( 'tags-apply-blocked' );
 391                         }
 392                 }
 393
 394                 // to be applied, a tag has to be explicitly defined
 395                 // @todo Allow extensions to define tags that can be applied by users...
 396                 $allowedTags = self::listExplicitlyDefinedTags();
 397                 $disallowedTags = array_diff( $tags, $allowedTags );
 398                 if ( $disallowedTags ) {
 399                         return self::restrictedTagError( 'tags-apply-not-allowed-one',
 400                                 'tags-apply-not-allowed-multi', $disallowedTags );
 401                 }
 402
 403                 return Status::newGood();
 404         }
 405
 406         /**
 407          * Adds tags to a given change, checking whether it is allowed first, but
 408          * without adding a log entry. Useful for cases where the tag is being added
 409          * along with the action that generated the change (e.g. tagging an edit as
 410          * it is being made).
 411          *
 412          * Extensions should not use this function, unless directly handling a user
 413          * request to add a particular tag. Normally, extensions should call
 414          * ChangeTags::updateTags() instead.
 415          *
 416          * @param array $tags Tags to apply
 417          * @param int|null $rc_id The rc_id of the change to add the tags to
 418          * @param int|null $rev_id The rev_id of the change to add the tags to
 419          * @param int|null $log_id The log_id of the change to add the tags to
 420          * @param string $params Params to put in the ct_params field of table
 421          * 'change_tag' when adding tags
 422          * @param User $user Who to give credit for the action
 423          * @return Status
 424          * @since 1.25
 425          */
 426         public static function addTagsAccompanyingChangeWithChecks(
 427                 array $tags, $rc_id, $rev_id, $log_id, $params, User $user
 428         ) {
 429
 430                 // are we allowed to do this?
 431                 $result = self::canAddTagsAccompanyingChange( $tags, $user );
 432                 if ( !$result->isOK() ) {
 433                         $result->value = null;
 434                         return $result;
 435                 }
 436
 437                 // do it!
 438                 self::addTags( $tags, $rc_id, $rev_id, $log_id, $params );
 439
 440                 return Status::newGood( true );
 441         }
 442
 443         /**
 444          * Is it OK to allow the user to adds and remove the given tags tags to/from a
 445          * change?
 446          *
 447          * @param array $tagsToAdd Tags that you are interested in adding
 448          * @param array $tagsToRemove Tags that you are interested in removing
 449          * @param User|null $user User whose permission you wish to check, or null if
 450          * you don't care (e.g. maintenance scripts)
 451          * @return Status
 452          * @since 1.25
 453          */
 454         public static function canUpdateTags( array $tagsToAdd, array $tagsToRemove,
 455                 User $user = null ) {
 456
 457                 if ( !is_null( $user ) ) {
 458                         if ( !$user->isAllowed( 'changetags' ) ) {
 459                                 return Status::newFatal( 'tags-update-no-permission' );
 460                         } elseif ( $user->isBlocked() ) {
 461                                 return Status::newFatal( 'tags-update-blocked' );
 462                         }
 463                 }
 464
 465                 if ( $tagsToAdd ) {
 466                         // to be added, a tag has to be explicitly defined
 467                         // @todo Allow extensions to define tags that can be applied by users...
 468                         $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
 469                         $diff = array_diff( $tagsToAdd, $explicitlyDefinedTags );
 470                         if ( $diff ) {
 471                                 return self::restrictedTagError( 'tags-update-add-not-allowed-one',
 472                                         'tags-update-add-not-allowed-multi', $diff );
 473                         }
 474                 }
 475
 476                 if ( $tagsToRemove ) {
 477                         // to be removed, a tag must not be defined by an extension, or equivalently it
 478                         // has to be either explicitly defined or not defined at all
 479                         // (assuming no edge case of a tag both explicitly-defined and extension-defined)
 480                         $softwareDefinedTags = self::listSoftwareDefinedTags();
 481                         $intersect = array_intersect( $tagsToRemove, $softwareDefinedTags );
 482                         if ( $intersect ) {
 483                                 return self::restrictedTagError( 'tags-update-remove-not-allowed-one',
 484                                         'tags-update-remove-not-allowed-multi', $intersect );
 485                         }
 486                 }
 487
 488                 return Status::newGood();
 489         }
 490
 491         /**
 492          * Adds and/or removes tags to/from a given change, checking whether it is
 493          * allowed first, and adding a log entry afterwards.
 494          *
 495          * Includes a call to ChangeTag::canUpdateTags(), so your code doesn't need
 496          * to do that. However, it doesn't check whether the *_id parameters are a
 497          * valid combination. That is up to you to enforce. See ApiTag::execute() for
 498          * an example.
 499          *
 500          * @param array|null $tagsToAdd If none, pass array() or null
 501          * @param array|null $tagsToRemove If none, pass array() or null
 502          * @param int|null $rc_id The rc_id of the change to add the tags to
 503          * @param int|null $rev_id The rev_id of the change to add the tags to
 504          * @param int|null $log_id The log_id of the change to add the tags to
 505          * @param string $params Params to put in the ct_params field of table
 506          * 'change_tag' when adding tags
 507          * @param string $reason Comment for the log
 508          * @param User $user Who to give credit for the action
 509          * @return Status If successful, the value of this Status object will be an
 510          * object (stdClass) with the following fields:
 511          *  - logId: the ID of the added log entry, or null if no log entry was added
 512          *    (i.e. no operation was performed)
 513          *  - addedTags: an array containing the tags that were actually added
 514          *  - removedTags: an array containing the tags that were actually removed
 515          * @since 1.25
 516          */
 517         public static function updateTagsWithChecks( $tagsToAdd, $tagsToRemove,
 518                 $rc_id, $rev_id, $log_id, $params, $reason, User $user ) {
 519
 520                 if ( is_null( $tagsToAdd ) ) {
 521                         $tagsToAdd = [];
 522                 }
 523                 if ( is_null( $tagsToRemove ) ) {
 524                         $tagsToRemove = [];
 525                 }
 526                 if ( !$tagsToAdd && !$tagsToRemove ) {
 527                         // no-op, don't bother
 528                         return Status::newGood( (object)[
 529                                 'logId' => null,
 530                                 'addedTags' => [],
 531                                 'removedTags' => [],
 532                         ] );
 533                 }
 534
 535                 // are we allowed to do this?
 536                 $result = self::canUpdateTags( $tagsToAdd, $tagsToRemove, $user );
 537                 if ( !$result->isOK() ) {
 538                         $result->value = null;
 539                         return $result;
 540                 }
 541
 542                 // basic rate limiting
 543                 if ( $user->pingLimiter( 'changetag' ) ) {
 544                         return Status::newFatal( 'actionthrottledtext' );
 545                 }
 546
 547                 // do it!
 548                 list( $tagsAdded, $tagsRemoved, $initialTags ) = self::updateTags( $tagsToAdd,
 549                         $tagsToRemove, $rc_id, $rev_id, $log_id, $params );
 550                 if ( !$tagsAdded && !$tagsRemoved ) {
 551                         // no-op, don't log it
 552                         return Status::newGood( (object)[
 553                                 'logId' => null,
 554                                 'addedTags' => [],
 555                                 'removedTags' => [],
 556                         ] );
 557                 }
 558
 559                 // log it
 560                 $logEntry = new ManualLogEntry( 'tag', 'update' );
 561                 $logEntry->setPerformer( $user );
 562                 $logEntry->setComment( $reason );
 563
 564                 // find the appropriate target page
 565                 if ( $rev_id ) {
 566                         $rev = Revision::newFromId( $rev_id );
 567                         if ( $rev ) {
 568                                 $logEntry->setTarget( $rev->getTitle() );
 569                         }
 570                 } elseif ( $log_id ) {
 571                         // This function is from revision deletion logic and has nothing to do with
 572                         // change tags, but it appears to be the only other place in core where we
 573                         // perform logged actions on log items.
 574                         $logEntry->setTarget( RevDelLogList::suggestTarget( null, [ $log_id ] ) );
 575                 }
 576
 577                 if ( !$logEntry->getTarget() ) {
 578                         // target is required, so we have to set something
 579                         $logEntry->setTarget( SpecialPage::getTitleFor( 'Tags' ) );
 580                 }
 581
 582                 $logParams = [
 583                         '4::revid' => $rev_id,
 584                         '5::logid' => $log_id,
 585                         '6:list:tagsAdded' => $tagsAdded,
 586                         '7:number:tagsAddedCount' => count( $tagsAdded ),
 587                         '8:list:tagsRemoved' => $tagsRemoved,
 588                         '9:number:tagsRemovedCount' => count( $tagsRemoved ),
 589                         'initialTags' => $initialTags,
 590                 ];
 591                 $logEntry->setParameters( $logParams );
 592                 $logEntry->setRelations( [ 'Tag' => array_merge( $tagsAdded, $tagsRemoved ) ] );
 593
 594                 $dbw = wfGetDB( DB_MASTER );
 595                 $logId = $logEntry->insert( $dbw );
 596                 // Only send this to UDP, not RC, similar to patrol events
 597                 $logEntry->publish( $logId, 'udp' );
 598
 599                 return Status::newGood( (object)[
 600                         'logId' => $logId,
 601                         'addedTags' => $tagsAdded,
 602                         'removedTags' => $tagsRemoved,
 603                 ] );
 604         }
 605
 606         /**
 607          * Applies all tags-related changes to a query.
 608          * Handles selecting tags, and filtering.
 609          * Needs $tables to be set up properly, so we can figure out which join conditions to use.
 610          *
 611          * @param string|array $tables Table names, see DatabaseBase::select
 612          * @param string|array $fields Fields used in query, see DatabaseBase::select
 613          * @param string|array $conds Conditions used in query, see DatabaseBase::select
 614          * @param array $join_conds Join conditions, see DatabaseBase::select
 615          * @param array $options Options, see Database::select
 616          * @param bool|string $filter_tag Tag to select on
 617          *
 618          * @throws MWException When unable to determine appropriate JOIN condition for tagging
 619          */
 620         public static function modifyDisplayQuery( &$tables, &$fields, &$conds,
 621                                                                                 &$join_conds, &$options, $filter_tag = false ) {
 622                 global $wgRequest, $wgUseTagFilter;
 623
 624                 if ( $filter_tag === false ) {
 625                         $filter_tag = $wgRequest->getVal( 'tagfilter' );
 626                 }
 627
 628                 // Figure out which conditions can be done.
 629                 if ( in_array( 'recentchanges', $tables ) ) {
 630                         $join_cond = 'ct_rc_id=rc_id';
 631                 } elseif ( in_array( 'logging', $tables ) ) {
 632                         $join_cond = 'ct_log_id=log_id';
 633                 } elseif ( in_array( 'revision', $tables ) ) {
 634                         $join_cond = 'ct_rev_id=rev_id';
 635                 } elseif ( in_array( 'archive', $tables ) ) {
 636                         $join_cond = 'ct_rev_id=ar_rev_id';
 637                 } else {
 638                         throw new MWException( 'Unable to determine appropriate JOIN condition for tagging.' );
 639                 }
 640
 641                 $fields['ts_tags'] = wfGetDB( DB_REPLICA )->buildGroupConcatField(
 642                         ',', 'change_tag', 'ct_tag', $join_cond
 643                 );
 644
 645                 if ( $wgUseTagFilter && $filter_tag ) {
 646                         // Somebody wants to filter on a tag.
 647                         // Add an INNER JOIN on change_tag
 648
 649                         $tables[] = 'change_tag';
 650                         $join_conds['change_tag'] = [ 'INNER JOIN', $join_cond ];
 651                         $conds['ct_tag'] = $filter_tag;
 652                 }
 653         }
 654
 655         /**
 656          * Build a text box to select a change tag
 657          *
 658          * @param string $selected Tag to select by default
 659          * @param bool $ooui Use an OOUI TextInputWidget as selector instead of a non-OOUI input field
 660          *        You need to call OutputPage::enableOOUI() yourself.
 661          * @return array an array of (label, selector)
 662          */
 663         public static function buildTagFilterSelector( $selected = '', $ooui = false ) {
 664                 global $wgUseTagFilter;
 665
 666                 if ( !$wgUseTagFilter || !count( self::listDefinedTags() ) ) {
 667                         return [];
 668                 }
 669
 670                 $data = [
 671                         Html::rawElement(
 672                                 'label',
 673                                 [ 'for' => 'tagfilter' ],
 674                                 wfMessage( 'tag-filter' )->parse()
 675                         )
 676                 ];
 677
 678                 if ( $ooui ) {
 679                         $data[] = new OOUI\TextInputWidget( [
 680                                 'id' => 'tagfilter',
 681                                 'name' => 'tagfilter',
 682                                 'value' => $selected,
 683                                 'classes' => 'mw-tagfilter-input',
 684                         ] );
 685                 } else {
 686                         $data[] = Xml::input(
 687                                 'tagfilter',
 688                                 20,
 689                                 $selected,
 690                                 [ 'class' => 'mw-tagfilter-input mw-ui-input mw-ui-input-inline', 'id' => 'tagfilter' ]
 691                         );
 692                 }
 693
 694                 return $data;
 695         }
 696
 697         /**
 698          * Defines a tag in the valid_tag table, without checking that the tag name
 699          * is valid.
 700          * Extensions should NOT use this function; they can use the ListDefinedTags
 701          * hook instead.
 702          *
 703          * @param string $tag Tag to create
 704          * @since 1.25
 705          */
 706         public static function defineTag( $tag ) {
 707                 $dbw = wfGetDB( DB_MASTER );
 708                 $dbw->replace( 'valid_tag',
 709                         [ 'vt_tag' ],
 710                         [ 'vt_tag' => $tag ],
 711                         __METHOD__ );
 712
 713                 // clear the memcache of defined tags
 714                 self::purgeTagCacheAll();
 715         }
 716
 717         /**
 718          * Removes a tag from the valid_tag table. The tag may remain in use by
 719          * extensions, and may still show up as 'defined' if an extension is setting
 720          * it from the ListDefinedTags hook.
 721          *
 722          * @param string $tag Tag to remove
 723          * @since 1.25
 724          */
 725         public static function undefineTag( $tag ) {
 726                 $dbw = wfGetDB( DB_MASTER );
 727                 $dbw->delete( 'valid_tag', [ 'vt_tag' => $tag ], __METHOD__ );
 728
 729                 // clear the memcache of defined tags
 730                 self::purgeTagCacheAll();
 731         }
 732
 733         /**
 734          * Writes a tag action into the tag management log.
 735          *
 736          * @param string $action
 737          * @param string $tag
 738          * @param string $reason
 739          * @param User $user Who to attribute the action to
 740          * @param int $tagCount For deletion only, how many usages the tag had before
 741          * it was deleted.
 742          * @return int ID of the inserted log entry
 743          * @since 1.25
 744          */
 745         protected static function logTagManagementAction( $action, $tag, $reason,
 746                 User $user, $tagCount = null ) {
 747
 748                 $dbw = wfGetDB( DB_MASTER );
 749
 750                 $logEntry = new ManualLogEntry( 'managetags', $action );
 751                 $logEntry->setPerformer( $user );
 752                 // target page is not relevant, but it has to be set, so we just put in
 753                 // the title of Special:Tags
 754                 $logEntry->setTarget( Title::newFromText( 'Special:Tags' ) );
 755                 $logEntry->setComment( $reason );
 756
 757                 $params = [ '4::tag' => $tag ];
 758                 if ( !is_null( $tagCount ) ) {
 759                         $params['5:number:count'] = $tagCount;
 760                 }
 761                 $logEntry->setParameters( $params );
 762                 $logEntry->setRelations( [ 'Tag' => $tag ] );
 763
 764                 $logId = $logEntry->insert( $dbw );
 765                 $logEntry->publish( $logId );
 766                 return $logId;
 767         }
 768
 769         /**
 770          * Is it OK to allow the user to activate this tag?
 771          *
 772          * @param string $tag Tag that you are interested in activating
 773          * @param User|null $user User whose permission you wish to check, or null if
 774          * you don't care (e.g. maintenance scripts)
 775          * @return Status
 776          * @since 1.25
 777          */
 778         public static function canActivateTag( $tag, User $user = null ) {
 779                 if ( !is_null( $user ) ) {
 780                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 781                                 return Status::newFatal( 'tags-manage-no-permission' );
 782                         } elseif ( $user->isBlocked() ) {
 783                                 return Status::newFatal( 'tags-manage-blocked' );
 784                         }
 785                 }
 786
 787                 // defined tags cannot be activated (a defined tag is either extension-
 788                 // defined, in which case the extension chooses whether or not to active it;
 789                 // or user-defined, in which case it is considered active)
 790                 $definedTags = self::listDefinedTags();
 791                 if ( in_array( $tag, $definedTags ) ) {
 792                         return Status::newFatal( 'tags-activate-not-allowed', $tag );
 793                 }
 794
 795                 // non-existing tags cannot be activated
 796                 $tagUsage = self::tagUsageStatistics();
 797                 if ( !isset( $tagUsage[$tag] ) ) { // we already know the tag is undefined
 798                         return Status::newFatal( 'tags-activate-not-found', $tag );
 799                 }
 800
 801                 return Status::newGood();
 802         }
 803
 804         /**
 805          * Activates a tag, checking whether it is allowed first, and adding a log
 806          * entry afterwards.
 807          *
 808          * Includes a call to ChangeTag::canActivateTag(), so your code doesn't need
 809          * to do that.
 810          *
 811          * @param string $tag
 812          * @param string $reason
 813          * @param User $user Who to give credit for the action
 814          * @param bool $ignoreWarnings Can be used for API interaction, default false
 815          * @return Status If successful, the Status contains the ID of the added log
 816          * entry as its value
 817          * @since 1.25
 818          */
 819         public static function activateTagWithChecks( $tag, $reason, User $user,
 820                 $ignoreWarnings = false ) {
 821
 822                 // are we allowed to do this?
 823                 $result = self::canActivateTag( $tag, $user );
 824                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
 825                         $result->value = null;
 826                         return $result;
 827                 }
 828
 829                 // do it!
 830                 self::defineTag( $tag );
 831
 832                 // log it
 833                 $logId = self::logTagManagementAction( 'activate', $tag, $reason, $user );
 834                 return Status::newGood( $logId );
 835         }
 836
 837         /**
 838          * Is it OK to allow the user to deactivate this tag?
 839          *
 840          * @param string $tag Tag that you are interested in deactivating
 841          * @param User|null $user User whose permission you wish to check, or null if
 842          * you don't care (e.g. maintenance scripts)
 843          * @return Status
 844          * @since 1.25
 845          */
 846         public static function canDeactivateTag( $tag, User $user = null ) {
 847                 if ( !is_null( $user ) ) {
 848                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 849                                 return Status::newFatal( 'tags-manage-no-permission' );
 850                         } elseif ( $user->isBlocked() ) {
 851                                 return Status::newFatal( 'tags-manage-blocked' );
 852                         }
 853                 }
 854
 855                 // only explicitly-defined tags can be deactivated
 856                 $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
 857                 if ( !in_array( $tag, $explicitlyDefinedTags ) ) {
 858                         return Status::newFatal( 'tags-deactivate-not-allowed', $tag );
 859                 }
 860                 return Status::newGood();
 861         }
 862
 863         /**
 864          * Deactivates a tag, checking whether it is allowed first, and adding a log
 865          * entry afterwards.
 866          *
 867          * Includes a call to ChangeTag::canDeactivateTag(), so your code doesn't need
 868          * to do that.
 869          *
 870          * @param string $tag
 871          * @param string $reason
 872          * @param User $user Who to give credit for the action
 873          * @param bool $ignoreWarnings Can be used for API interaction, default false
 874          * @return Status If successful, the Status contains the ID of the added log
 875          * entry as its value
 876          * @since 1.25
 877          */
 878         public static function deactivateTagWithChecks( $tag, $reason, User $user,
 879                 $ignoreWarnings = false ) {
 880
 881                 // are we allowed to do this?
 882                 $result = self::canDeactivateTag( $tag, $user );
 883                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
 884                         $result->value = null;
 885                         return $result;
 886                 }
 887
 888                 // do it!
 889                 self::undefineTag( $tag );
 890
 891                 // log it
 892                 $logId = self::logTagManagementAction( 'deactivate', $tag, $reason, $user );
 893                 return Status::newGood( $logId );
 894         }
 895
 896         /**
 897          * Is it OK to allow the user to create this tag?
 898          *
 899          * @param string $tag Tag that you are interested in creating
 900          * @param User|null $user User whose permission you wish to check, or null if
 901          * you don't care (e.g. maintenance scripts)
 902          * @return Status
 903          * @since 1.25
 904          */
 905         public static function canCreateTag( $tag, User $user = null ) {
 906                 if ( !is_null( $user ) ) {
 907                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 908                                 return Status::newFatal( 'tags-manage-no-permission' );
 909                         } elseif ( $user->isBlocked() ) {
 910                                 return Status::newFatal( 'tags-manage-blocked' );
 911                         }
 912                 }
 913
 914                 // no empty tags
 915                 if ( $tag === '' ) {
 916                         return Status::newFatal( 'tags-create-no-name' );
 917                 }
 918
 919                 // tags cannot contain commas (used as a delimiter in tag_summary table) or
 920                 // slashes (would break tag description messages in MediaWiki namespace)
 921                 if ( strpos( $tag, ',' ) !== false || strpos( $tag, '/' ) !== false ) {
 922                         return Status::newFatal( 'tags-create-invalid-chars' );
 923                 }
 924
 925                 // could the MediaWiki namespace description messages be created?
 926                 $title = Title::makeTitleSafe( NS_MEDIAWIKI, "Tag-$tag-description" );
 927                 if ( is_null( $title ) ) {
 928                         return Status::newFatal( 'tags-create-invalid-title-chars' );
 929                 }
 930
 931                 // does the tag already exist?
 932                 $tagUsage = self::tagUsageStatistics();
 933                 if ( isset( $tagUsage[$tag] ) || in_array( $tag, self::listDefinedTags() ) ) {
 934                         return Status::newFatal( 'tags-create-already-exists', $tag );
 935                 }
 936
 937                 // check with hooks
 938                 $canCreateResult = Status::newGood();
 939                 Hooks::run( 'ChangeTagCanCreate', [ $tag, $user, &$canCreateResult ] );
 940                 return $canCreateResult;
 941         }
 942
 943         /**
 944          * Creates a tag by adding a row to the `valid_tag` table.
 945          *
 946          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
 947          * do that.
 948          *
 949          * @param string $tag
 950          * @param string $reason
 951          * @param User $user Who to give credit for the action
 952          * @param bool $ignoreWarnings Can be used for API interaction, default false
 953          * @return Status If successful, the Status contains the ID of the added log
 954          * entry as its value
 955          * @since 1.25
 956          */
 957         public static function createTagWithChecks( $tag, $reason, User $user,
 958                 $ignoreWarnings = false ) {
 959
 960                 // are we allowed to do this?
 961                 $result = self::canCreateTag( $tag, $user );
 962                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
 963                         $result->value = null;
 964                         return $result;
 965                 }
 966
 967                 // do it!
 968                 self::defineTag( $tag );
 969
 970                 // log it
 971                 $logId = self::logTagManagementAction( 'create', $tag, $reason, $user );
 972                 return Status::newGood( $logId );
 973         }
 974
 975         /**
 976          * Permanently removes all traces of a tag from the DB. Good for removing
 977          * misspelt or temporary tags.
 978          *
 979          * This function should be directly called by maintenance scripts only, never
 980          * by user-facing code. See deleteTagWithChecks() for functionality that can
 981          * safely be exposed to users.
 982          *
 983          * @param string $tag Tag to remove
 984          * @return Status The returned status will be good unless a hook changed it
 985          * @since 1.25
 986          */
 987         public static function deleteTagEverywhere( $tag ) {
 988                 $dbw = wfGetDB( DB_MASTER );
 989                 $dbw->startAtomic( __METHOD__ );
 990
 991                 // delete from valid_tag
 992                 self::undefineTag( $tag );
 993
 994                 // find out which revisions use this tag, so we can delete from tag_summary
 995                 $result = $dbw->select( 'change_tag',
 996                         [ 'ct_rc_id', 'ct_log_id', 'ct_rev_id', 'ct_tag' ],
 997                         [ 'ct_tag' => $tag ],
 998                         __METHOD__ );
 999                 foreach ( $result as $row ) {
1000                         // remove the tag from the relevant row of tag_summary
1001                         $tagsToAdd = [];
1002                         $tagsToRemove = [ $tag ];
1003                         self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $row->ct_rc_id,
1004                                 $row->ct_rev_id, $row->ct_log_id );
1005                 }
1006
1007                 // delete from change_tag
1008                 $dbw->delete( 'change_tag', [ 'ct_tag' => $tag ], __METHOD__ );
1009
1010                 $dbw->endAtomic( __METHOD__ );
1011
1012                 // give extensions a chance
1013                 $status = Status::newGood();
1014                 Hooks::run( 'ChangeTagAfterDelete', [ $tag, &$status ] );
1015                 // let's not allow error results, as the actual tag deletion succeeded
1016                 if ( !$status->isOK() ) {
1017                         wfDebug( 'ChangeTagAfterDelete error condition downgraded to warning' );
1018                         $status->setOK( true );
1019                 }
1020
1021                 // clear the memcache of defined tags
1022                 self::purgeTagCacheAll();
1023
1024                 return $status;
1025         }
1026
1027         /**
1028          * Is it OK to allow the user to delete this tag?
1029          *
1030          * @param string $tag Tag that you are interested in deleting
1031          * @param User|null $user User whose permission you wish to check, or null if
1032          * you don't care (e.g. maintenance scripts)
1033          * @return Status
1034          * @since 1.25
1035          */
1036         public static function canDeleteTag( $tag, User $user = null ) {
1037                 $tagUsage = self::tagUsageStatistics();
1038
1039                 if ( !is_null( $user ) ) {
1040                         if ( !$user->isAllowed( 'deletechangetags' ) ) {
1041                                 return Status::newFatal( 'tags-delete-no-permission' );
1042                         } elseif ( $user->isBlocked() ) {
1043                                 return Status::newFatal( 'tags-manage-blocked' );
1044                         }
1045                 }
1046
1047                 if ( !isset( $tagUsage[$tag] ) && !in_array( $tag, self::listDefinedTags() ) ) {
1048                         return Status::newFatal( 'tags-delete-not-found', $tag );
1049                 }
1050
1051                 if ( isset( $tagUsage[$tag] ) && $tagUsage[$tag] > self::MAX_DELETE_USES ) {
1052                         return Status::newFatal( 'tags-delete-too-many-uses', $tag, self::MAX_DELETE_USES );
1053                 }
1054
1055                 $softwareDefined = self::listSoftwareDefinedTags();
1056                 if ( in_array( $tag, $softwareDefined ) ) {
1057                         // extension-defined tags can't be deleted unless the extension
1058                         // specifically allows it
1059                         $status = Status::newFatal( 'tags-delete-not-allowed' );
1060                 } else {
1061                         // user-defined tags are deletable unless otherwise specified
1062                         $status = Status::newGood();
1063                 }
1064
1065                 Hooks::run( 'ChangeTagCanDelete', [ $tag, $user, &$status ] );
1066                 return $status;
1067         }
1068
1069         /**
1070          * Deletes a tag, checking whether it is allowed first, and adding a log entry
1071          * afterwards.
1072          *
1073          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
1074          * do that.
1075          *
1076          * @param string $tag
1077          * @param string $reason
1078          * @param User $user Who to give credit for the action
1079          * @param bool $ignoreWarnings Can be used for API interaction, default false
1080          * @return Status If successful, the Status contains the ID of the added log
1081          * entry as its value
1082          * @since 1.25
1083          */
1084         public static function deleteTagWithChecks( $tag, $reason, User $user,
1085                 $ignoreWarnings = false ) {
1086
1087                 // are we allowed to do this?
1088                 $result = self::canDeleteTag( $tag, $user );
1089                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1090                         $result->value = null;
1091                         return $result;
1092                 }
1093
1094                 // store the tag usage statistics
1095                 $tagUsage = self::tagUsageStatistics();
1096                 $hitcount = isset( $tagUsage[$tag] ) ? $tagUsage[$tag] : 0;
1097
1098                 // do it!
1099                 $deleteResult = self::deleteTagEverywhere( $tag );
1100                 if ( !$deleteResult->isOK() ) {
1101                         return $deleteResult;
1102                 }
1103
1104                 // log it
1105                 $logId = self::logTagManagementAction( 'delete', $tag, $reason, $user, $hitcount );
1106                 $deleteResult->value = $logId;
1107                 return $deleteResult;
1108         }
1109
1110         /**
1111          * Lists those tags which core or extensions report as being "active".
1112          *
1113          * @return array
1114          * @since 1.25
1115          */
1116         public static function listSoftwareActivatedTags() {
1117                 // core active tags
1118                 $tags = self::$coreTags;
1119                 if ( !Hooks::isRegistered( 'ChangeTagsListActive' ) ) {
1120                         return $tags;
1121                 }
1122                 return ObjectCache::getMainWANInstance()->getWithSetCallback(
1123                         wfMemcKey( 'active-tags' ),
1124                         WANObjectCache::TTL_MINUTE * 5,
1125                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1126                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1127
1128                                 // Ask extensions which tags they consider active
1129                                 Hooks::run( 'ChangeTagsListActive', [ &$tags ] );
1130                                 return $tags;
1131                         },
1132                         [
1133                                 'checkKeys' => [ wfMemcKey( 'active-tags' ) ],
1134                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1135                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1136                         ]
1137                 );
1138         }
1139
1140         /**
1141          * @see listSoftwareActivatedTags
1142          * @deprecated since 1.28 call listSoftwareActivatedTags directly
1143          * @return array
1144          */
1145         public static function listExtensionActivatedTags() {
1146                 wfDeprecated( __METHOD__, '1.28' );
1147                 return self::listSoftwareActivatedTags();
1148         }
1149
1150         /**
1151          * Basically lists defined tags which count even if they aren't applied to anything.
1152          * It returns a union of the results of listExplicitlyDefinedTags() and
1153          * listExtensionDefinedTags().
1154          *
1155          * @return string[] Array of strings: tags
1156          */
1157         public static function listDefinedTags() {
1158                 $tags1 = self::listExplicitlyDefinedTags();
1159                 $tags2 = self::listSoftwareDefinedTags();
1160                 return array_values( array_unique( array_merge( $tags1, $tags2 ) ) );
1161         }
1162
1163         /**
1164          * Lists tags explicitly defined in the `valid_tag` table of the database.
1165          * Tags in table 'change_tag' which are not in table 'valid_tag' are not
1166          * included.
1167          *
1168          * Tries memcached first.
1169          *
1170          * @return string[] Array of strings: tags
1171          * @since 1.25
1172          */
1173         public static function listExplicitlyDefinedTags() {
1174                 $fname = __METHOD__;
1175
1176                 return ObjectCache::getMainWANInstance()->getWithSetCallback(
1177                         wfMemcKey( 'valid-tags-db' ),
1178                         WANObjectCache::TTL_MINUTE * 5,
1179                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1180                                 $dbr = wfGetDB( DB_REPLICA );
1181
1182                                 $setOpts += Database::getCacheSetOptions( $dbr );
1183
1184                                 $tags = $dbr->selectFieldValues( 'valid_tag', 'vt_tag', [], $fname );
1185
1186                                 return array_filter( array_unique( $tags ) );
1187                         },
1188                         [
1189                                 'checkKeys' => [ wfMemcKey( 'valid-tags-db' ) ],
1190                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1191                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1192                         ]
1193                 );
1194         }
1195
1196         /**
1197          * Lists tags defined by core or extensions using the ListDefinedTags hook.
1198          * Extensions need only define those tags they deem to be in active use.
1199          *
1200          * Tries memcached first.
1201          *
1202          * @return string[] Array of strings: tags
1203          * @since 1.25
1204          */
1205         public static function listSoftwareDefinedTags() {
1206                 // core defined tags
1207                 $tags = self::$coreTags;
1208                 if ( !Hooks::isRegistered( 'ListDefinedTags' ) ) {
1209                         return $tags;
1210                 }
1211                 return ObjectCache::getMainWANInstance()->getWithSetCallback(
1212                         wfMemcKey( 'valid-tags-hook' ),
1213                         WANObjectCache::TTL_MINUTE * 5,
1214                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1215                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1216
1217                                 Hooks::run( 'ListDefinedTags', [ &$tags ] );
1218                                 return array_filter( array_unique( $tags ) );
1219                         },
1220                         [
1221                                 'checkKeys' => [ wfMemcKey( 'valid-tags-hook' ) ],
1222                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1223                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1224                         ]
1225                 );
1226         }
1227
1228         /**
1229          * Call listSoftwareDefinedTags directly
1230          *
1231          * @see listSoftwareDefinedTags
1232          * @deprecated since 1.28
1233          */
1234         public static function listExtensionDefinedTags() {
1235                 wfDeprecated( __METHOD__, '1.28' );
1236                 return self::listSoftwareDefinedTags();
1237         }
1238
1239         /**
1240          * Invalidates the short-term cache of defined tags used by the
1241          * list*DefinedTags functions, as well as the tag statistics cache.
1242          * @since 1.25
1243          */
1244         public static function purgeTagCacheAll() {
1245                 $cache = ObjectCache::getMainWANInstance();
1246
1247                 $cache->touchCheckKey( wfMemcKey( 'active-tags' ) );
1248                 $cache->touchCheckKey( wfMemcKey( 'valid-tags-db' ) );
1249                 $cache->touchCheckKey( wfMemcKey( 'valid-tags-hook' ) );
1250
1251                 self::purgeTagUsageCache();
1252         }
1253
1254         /**
1255          * Invalidates the tag statistics cache only.
1256          * @since 1.25
1257          */
1258         public static function purgeTagUsageCache() {
1259                 $cache = ObjectCache::getMainWANInstance();
1260
1261                 $cache->touchCheckKey( wfMemcKey( 'change-tag-statistics' ) );
1262         }
1263
1264         /**
1265          * Returns a map of any tags used on the wiki to number of edits
1266          * tagged with them, ordered descending by the hitcount.
1267          * This does not include tags defined somewhere that have never been applied.
1268          *
1269          * Keeps a short-term cache in memory, so calling this multiple times in the
1270          * same request should be fine.
1271          *
1272          * @return array Array of string => int
1273          */
1274         public static function tagUsageStatistics() {
1275                 $fname = __METHOD__;
1276                 return ObjectCache::getMainWANInstance()->getWithSetCallback(
1277                         wfMemcKey( 'change-tag-statistics' ),
1278                         WANObjectCache::TTL_MINUTE * 5,
1279                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1280                                 $dbr = wfGetDB( DB_REPLICA, 'vslow' );
1281
1282                                 $setOpts += Database::getCacheSetOptions( $dbr );
1283
1284                                 $res = $dbr->select(
1285                                         'change_tag',
1286                                         [ 'ct_tag', 'hitcount' => 'count(*)' ],
1287                                         [],
1288                                         $fname,
1289                                         [ 'GROUP BY' => 'ct_tag', 'ORDER BY' => 'hitcount DESC' ]
1290                                 );
1291
1292                                 $out = [];
1293                                 foreach ( $res as $row ) {
1294                                         $out[$row->ct_tag] = $row->hitcount;
1295                                 }
1296
1297                                 return $out;
1298                         },
1299                         [
1300                                 'checkKeys' => [ wfMemcKey( 'change-tag-statistics' ) ],
1301                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1302                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1303                         ]
1304                 );
1305         }
1306
1307         /**
1308          * Indicate whether change tag editing UI is relevant
1309          *
1310          * Returns true if the user has the necessary right and there are any
1311          * editable tags defined.
1312          *
1313          * This intentionally doesn't check "any addable || any deletable", because
1314          * it seems like it would be more confusing than useful if the checkboxes
1315          * suddenly showed up because some abuse filter stopped defining a tag and
1316          * then suddenly disappeared when someone deleted all uses of that tag.
1317          *
1318          * @param User $user
1319          * @return bool
1320          */
1321         public static function showTagEditingUI( User $user ) {
1322                 return $user->isAllowed( 'changetags' ) && (bool)self::listExplicitlyDefinedTags();
1323         }
1324 }