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 use MediaWiki\MediaWikiServices;
  25 use Wikimedia\Rdbms\Database;
  26
  27 class ChangeTags {
  28         /**
  29          * Can't delete tags with more than this many uses. Similar in intent to
  30          * the bigdelete user right
  31          * @todo Use the job queue for tag deletion to avoid this restriction
  32          */
  33         const MAX_DELETE_USES = 5000;
  34
  35         /**
  36          * @var string[]
  37          */
  38         private static $coreTags = [ 'mw-contentmodelchange' ];
  39
  40         /**
  41          * Creates HTML for the given tags
  42          *
  43          * @param string $tags Comma-separated list of tags
  44          * @param string $page A label for the type of action which is being displayed,
  45          *   for example: 'history', 'contributions' or 'newpages'
  46          * @param IContextSource|null $context
  47          * @note Even though it takes null as a valid argument, an IContextSource is preferred
  48          *       in a new code, as the null value is subject to change in the future
  49          * @return array Array with two items: (html, classes)
  50          *   - html: String: HTML for displaying the tags (empty string when param $tags is empty)
  51          *   - classes: Array of strings: CSS classes used in the generated html, one class for each tag
  52          */
  53         public static function formatSummaryRow( $tags, $page, IContextSource $context = null ) {
  54                 if ( !$tags ) {
  55                         return [ '', [] ];
  56                 }
  57                 if ( !$context ) {
  58                         $context = RequestContext::getMain();
  59                 }
  60
  61                 $classes = [];
  62
  63                 $tags = explode( ',', $tags );
  64                 $displayTags = [];
  65                 foreach ( $tags as $tag ) {
  66                         if ( !$tag ) {
  67                                 continue;
  68                         }
  69                         $description = self::tagDescription( $tag, $context );
  70                         if ( $description === false ) {
  71                                 continue;
  72                         }
  73                         $displayTags[] = Xml::tags(
  74                                 'span',
  75                                 [ 'class' => 'mw-tag-marker ' .
  76                                                                 Sanitizer::escapeClass( "mw-tag-marker-$tag" ) ],
  77                                 $description
  78                         );
  79                         $classes[] = Sanitizer::escapeClass( "mw-tag-$tag" );
  80                 }
  81
  82                 if ( !$displayTags ) {
  83                         return [ '', [] ];
  84                 }
  85
  86                 $markers = $context->msg( 'tag-list-wrapper' )
  87                         ->numParams( count( $displayTags ) )
  88                         ->rawParams( $context->getLanguage()->commaList( $displayTags ) )
  89                         ->parse();
  90                 $markers = Xml::tags( 'span', [ 'class' => 'mw-tag-markers' ], $markers );
  91
  92                 return [ $markers, $classes ];
  93         }
  94
  95         /**
  96          * Get a short description for a tag.
  97          *
  98          * Checks if message key "mediawiki:tag-$tag" exists. If it does not,
  99          * returns the HTML-escaped tag name. Uses the message if the message
 100          * exists, provided it is not disabled. If the message is disabled,
 101          * we consider the tag hidden, and return false.
 102          *
 103          * @param string $tag Tag
 104          * @param IContextSource $context
 105          * @return string|bool Tag description or false if tag is to be hidden.
 106          * @since 1.25 Returns false if tag is to be hidden.
 107          */
 108         public static function tagDescription( $tag, IContextSource $context ) {
 109                 $msg = $context->msg( "tag-$tag" );
 110                 if ( !$msg->exists() ) {
 111                         // No such message, so return the HTML-escaped tag name.
 112                         return htmlspecialchars( $tag );
 113                 }
 114                 if ( $msg->isDisabled() ) {
 115                         // The message exists but is disabled, hide the tag.
 116                         return false;
 117                 }
 118
 119                 // Message exists and isn't disabled, use it.
 120                 return $msg->parse();
 121         }
 122
 123         /**
 124          * Get the message object for the tag's long description.
 125          *
 126          * Checks if message key "mediawiki:tag-$tag-description" exists. If it does not,
 127          * or if message is disabled, returns false. Otherwise, returns the message object
 128          * for the long description.
 129          *
 130          * @param string $tag Tag
 131          * @param IContextSource $context
 132          * @return Message|bool Message object of the tag long description or false if
 133          *  there is no description.
 134          */
 135         public static function tagLongDescriptionMessage( $tag, IContextSource $context ) {
 136                 $msg = $context->msg( "tag-$tag-description" );
 137                 if ( !$msg->exists() ) {
 138                         return false;
 139                 }
 140                 if ( $msg->isDisabled() ) {
 141                         // The message exists but is disabled, hide the description.
 142                         return false;
 143                 }
 144
 145                 // Message exists and isn't disabled, use it.
 146                 return $msg;
 147         }
 148
 149         /**
 150          * Add tags to a change given its rc_id, rev_id and/or log_id
 151          *
 152          * @param string|string[] $tags Tags to add to the change
 153          * @param int|null $rc_id The rc_id of the change to add the tags to
 154          * @param int|null $rev_id The rev_id of the change to add the tags to
 155          * @param int|null $log_id The log_id of the change to add the tags to
 156          * @param string $params Params to put in the ct_params field of table 'change_tag'
 157          * @param RecentChange|null $rc Recent change, in case the tagging accompanies the action
 158          * (this should normally be the case)
 159          *
 160          * @throws MWException
 161          * @return bool False if no changes are made, otherwise true
 162          */
 163         public static function addTags( $tags, $rc_id = null, $rev_id = null,
 164                 $log_id = null, $params = null, RecentChange $rc = null
 165         ) {
 166                 $result = self::updateTags( $tags, null, $rc_id, $rev_id, $log_id, $params, $rc );
 167                 return (bool)$result[0];
 168         }
 169
 170         /**
 171          * Add and remove tags to/from a change given its rc_id, rev_id and/or log_id,
 172          * without verifying that the tags exist or are valid. If a tag is present in
 173          * both $tagsToAdd and $tagsToRemove, it will be removed.
 174          *
 175          * This function should only be used by extensions to manipulate tags they
 176          * have registered using the ListDefinedTags hook. When dealing with user
 177          * input, call updateTagsWithChecks() instead.
 178          *
 179          * @param string|array|null $tagsToAdd Tags to add to the change
 180          * @param string|array|null $tagsToRemove Tags to remove from the change
 181          * @param int|null &$rc_id The rc_id of the change to add the tags to.
 182          * Pass a variable whose value is null if the rc_id is not relevant or unknown.
 183          * @param int|null &$rev_id The rev_id of the change to add the tags to.
 184          * Pass a variable whose value is null if the rev_id is not relevant or unknown.
 185          * @param int|null &$log_id The log_id of the change to add the tags to.
 186          * Pass a variable whose value is null if the log_id is not relevant or unknown.
 187          * @param string $params Params to put in the ct_params field of table
 188          * 'change_tag' when adding tags
 189          * @param RecentChange|null $rc Recent change being tagged, in case the tagging accompanies
 190          * the action
 191          * @param User|null $user Tagging user, in case the tagging is subsequent to the tagged action
 192          *
 193          * @throws MWException When $rc_id, $rev_id and $log_id are all null
 194          * @return array Index 0 is an array of tags actually added, index 1 is an
 195          * array of tags actually removed, index 2 is an array of tags present on the
 196          * revision or log entry before any changes were made
 197          *
 198          * @since 1.25
 199          */
 200         public static function updateTags( $tagsToAdd, $tagsToRemove, &$rc_id = null,
 201                 &$rev_id = null, &$log_id = null, $params = null, RecentChange $rc = null,
 202                 User $user = null
 203         ) {
 204
 205                 $tagsToAdd = array_filter( (array)$tagsToAdd ); // Make sure we're submitting all tags...
 206                 $tagsToRemove = array_filter( (array)$tagsToRemove );
 207
 208                 if ( !$rc_id && !$rev_id && !$log_id ) {
 209                         throw new MWException( 'At least one of: RCID, revision ID, and log ID MUST be ' .
 210                                 'specified when adding or removing a tag from a change!' );
 211                 }
 212
 213                 $dbw = wfGetDB( DB_MASTER );
 214
 215                 // Might as well look for rcids and so on.
 216                 if ( !$rc_id ) {
 217                         // Info might be out of date, somewhat fractionally, on replica DB.
 218                         // LogEntry/LogPage and WikiPage match rev/log/rc timestamps,
 219                         // so use that relation to avoid full table scans.
 220                         if ( $log_id ) {
 221                                 $rc_id = $dbw->selectField(
 222                                         [ 'logging', 'recentchanges' ],
 223                                         'rc_id',
 224                                         [
 225                                                 'log_id' => $log_id,
 226                                                 'rc_timestamp = log_timestamp',
 227                                                 'rc_logid = log_id'
 228                                         ],
 229                                         __METHOD__
 230                                 );
 231                         } elseif ( $rev_id ) {
 232                                 $rc_id = $dbw->selectField(
 233                                         [ 'revision', 'recentchanges' ],
 234                                         'rc_id',
 235                                         [
 236                                                 'rev_id' => $rev_id,
 237                                                 'rc_timestamp = rev_timestamp',
 238                                                 'rc_this_oldid = rev_id'
 239                                         ],
 240                                         __METHOD__
 241                                 );
 242                         }
 243                 } elseif ( !$log_id && !$rev_id ) {
 244                         // Info might be out of date, somewhat fractionally, on replica DB.
 245                         $log_id = $dbw->selectField(
 246                                 'recentchanges',
 247                                 'rc_logid',
 248                                 [ 'rc_id' => $rc_id ],
 249                                 __METHOD__
 250                         );
 251                         $rev_id = $dbw->selectField(
 252                                 'recentchanges',
 253                                 'rc_this_oldid',
 254                                 [ 'rc_id' => $rc_id ],
 255                                 __METHOD__
 256                         );
 257                 }
 258
 259                 if ( $log_id && !$rev_id ) {
 260                         $rev_id = $dbw->selectField(
 261                                 'log_search',
 262                                 'ls_value',
 263                                 [ 'ls_field' => 'associated_rev_id', 'ls_log_id' => $log_id ],
 264                                 __METHOD__
 265                         );
 266                 } elseif ( !$log_id && $rev_id ) {
 267                         $log_id = $dbw->selectField(
 268                                 'log_search',
 269                                 'ls_log_id',
 270                                 [ 'ls_field' => 'associated_rev_id', 'ls_value' => $rev_id ],
 271                                 __METHOD__
 272                         );
 273                 }
 274
 275                 // update the tag_summary row
 276                 $prevTags = [];
 277                 if ( !self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $rc_id, $rev_id,
 278                         $log_id, $prevTags ) ) {
 279
 280                         // nothing to do
 281                         return [ [], [], $prevTags ];
 282                 }
 283
 284                 // insert a row into change_tag for each new tag
 285                 if ( count( $tagsToAdd ) ) {
 286                         $tagsRows = [];
 287                         foreach ( $tagsToAdd as $tag ) {
 288                                 // Filter so we don't insert NULLs as zero accidentally.
 289                                 // Keep in mind that $rc_id === null means "I don't care/know about the
 290                                 // rc_id, just delete $tag on this revision/log entry". It doesn't
 291                                 // mean "only delete tags on this revision/log WHERE rc_id IS NULL".
 292                                 $tagsRows[] = array_filter(
 293                                         [
 294                                                 'ct_tag' => $tag,
 295                                                 'ct_rc_id' => $rc_id,
 296                                                 'ct_log_id' => $log_id,
 297                                                 'ct_rev_id' => $rev_id,
 298                                                 'ct_params' => $params
 299                                         ]
 300                                 );
 301                         }
 302
 303                         $dbw->insert( 'change_tag', $tagsRows, __METHOD__, [ 'IGNORE' ] );
 304                 }
 305
 306                 // delete from change_tag
 307                 if ( count( $tagsToRemove ) ) {
 308                         foreach ( $tagsToRemove as $tag ) {
 309                                 $conds = array_filter(
 310                                         [
 311                                                 'ct_tag' => $tag,
 312                                                 'ct_rc_id' => $rc_id,
 313                                                 'ct_log_id' => $log_id,
 314                                                 'ct_rev_id' => $rev_id
 315                                         ]
 316                                 );
 317                                 $dbw->delete( 'change_tag', $conds, __METHOD__ );
 318                         }
 319                 }
 320
 321                 self::purgeTagUsageCache();
 322
 323                 Hooks::run( 'ChangeTagsAfterUpdateTags', [ $tagsToAdd, $tagsToRemove, $prevTags,
 324                         $rc_id, $rev_id, $log_id, $params, $rc, $user ] );
 325
 326                 return [ $tagsToAdd, $tagsToRemove, $prevTags ];
 327         }
 328
 329         /**
 330          * Adds or removes a given set of tags to/from the relevant row of the
 331          * tag_summary table. Modifies the tagsToAdd and tagsToRemove arrays to
 332          * reflect the tags that were actually added and/or removed.
 333          *
 334          * @param array &$tagsToAdd
 335          * @param array &$tagsToRemove If a tag is present in both $tagsToAdd and
 336          * $tagsToRemove, it will be removed
 337          * @param int|null $rc_id Null if not known or not applicable
 338          * @param int|null $rev_id Null if not known or not applicable
 339          * @param int|null $log_id Null if not known or not applicable
 340          * @param array &$prevTags Optionally outputs a list of the tags that were
 341          * in the tag_summary row to begin with
 342          * @return bool True if any modifications were made, otherwise false
 343          * @since 1.25
 344          */
 345         protected static function updateTagSummaryRow( &$tagsToAdd, &$tagsToRemove,
 346                 $rc_id, $rev_id, $log_id, &$prevTags = [] ) {
 347
 348                 $dbw = wfGetDB( DB_MASTER );
 349
 350                 $tsConds = array_filter( [
 351                         'ts_rc_id' => $rc_id,
 352                         'ts_rev_id' => $rev_id,
 353                         'ts_log_id' => $log_id
 354                 ] );
 355
 356                 // Can't both add and remove a tag at the same time...
 357                 $tagsToAdd = array_diff( $tagsToAdd, $tagsToRemove );
 358
 359                 // Update the summary row.
 360                 // $prevTags can be out of date on replica DBs, especially when addTags is called consecutively,
 361                 // causing loss of tags added recently in tag_summary table.
 362                 $prevTags = $dbw->selectField( 'tag_summary', 'ts_tags', $tsConds, __METHOD__ );
 363                 $prevTags = $prevTags ? $prevTags : '';
 364                 $prevTags = array_filter( explode( ',', $prevTags ) );
 365
 366                 // add tags
 367                 $tagsToAdd = array_values( array_diff( $tagsToAdd, $prevTags ) );
 368                 $newTags = array_unique( array_merge( $prevTags, $tagsToAdd ) );
 369
 370                 // remove tags
 371                 $tagsToRemove = array_values( array_intersect( $tagsToRemove, $newTags ) );
 372                 $newTags = array_values( array_diff( $newTags, $tagsToRemove ) );
 373
 374                 sort( $prevTags );
 375                 sort( $newTags );
 376                 if ( $prevTags == $newTags ) {
 377                         // No change.
 378                         return false;
 379                 }
 380
 381                 if ( !$newTags ) {
 382                         // no tags left, so delete the row altogether
 383                         $dbw->delete( 'tag_summary', $tsConds, __METHOD__ );
 384                 } else {
 385                         $dbw->replace( 'tag_summary',
 386                                 [ 'ts_rev_id', 'ts_rc_id', 'ts_log_id' ],
 387                                 array_filter( array_merge( $tsConds, [ 'ts_tags' => implode( ',', $newTags ) ] ) ),
 388                                 __METHOD__
 389                         );
 390                 }
 391
 392                 return true;
 393         }
 394
 395         /**
 396          * Helper function to generate a fatal status with a 'not-allowed' type error.
 397          *
 398          * @param string $msgOne Message key to use in the case of one tag
 399          * @param string $msgMulti Message key to use in the case of more than one tag
 400          * @param array $tags Restricted tags (passed as $1 into the message, count of
 401          * $tags passed as $2)
 402          * @return Status
 403          * @since 1.25
 404          */
 405         protected static function restrictedTagError( $msgOne, $msgMulti, $tags ) {
 406                 $lang = RequestContext::getMain()->getLanguage();
 407                 $count = count( $tags );
 408                 return Status::newFatal( ( $count > 1 ) ? $msgMulti : $msgOne,
 409                         $lang->commaList( $tags ), $count );
 410         }
 411
 412         /**
 413          * Is it OK to allow the user to apply all the specified tags at the same time
 414          * as they edit/make the change?
 415          *
 416          * @param array $tags Tags that you are interested in applying
 417          * @param User|null $user User whose permission you wish to check, or null if
 418          * you don't care (e.g. maintenance scripts)
 419          * @return Status
 420          * @since 1.25
 421          */
 422         public static function canAddTagsAccompanyingChange( array $tags,
 423                 User $user = null ) {
 424
 425                 if ( !is_null( $user ) ) {
 426                         if ( !$user->isAllowed( 'applychangetags' ) ) {
 427                                 return Status::newFatal( 'tags-apply-no-permission' );
 428                         } elseif ( $user->isBlocked() ) {
 429                                 return Status::newFatal( 'tags-apply-blocked', $user->getName() );
 430                         }
 431                 }
 432
 433                 // to be applied, a tag has to be explicitly defined
 434                 $allowedTags = self::listExplicitlyDefinedTags();
 435                 Hooks::run( 'ChangeTagsAllowedAdd', [ &$allowedTags, $tags, $user ] );
 436                 $disallowedTags = array_diff( $tags, $allowedTags );
 437                 if ( $disallowedTags ) {
 438                         return self::restrictedTagError( 'tags-apply-not-allowed-one',
 439                                 'tags-apply-not-allowed-multi', $disallowedTags );
 440                 }
 441
 442                 return Status::newGood();
 443         }
 444
 445         /**
 446          * Adds tags to a given change, checking whether it is allowed first, but
 447          * without adding a log entry. Useful for cases where the tag is being added
 448          * along with the action that generated the change (e.g. tagging an edit as
 449          * it is being made).
 450          *
 451          * Extensions should not use this function, unless directly handling a user
 452          * request to add a particular tag. Normally, extensions should call
 453          * ChangeTags::updateTags() instead.
 454          *
 455          * @param array $tags Tags to apply
 456          * @param int|null $rc_id The rc_id of the change to add the tags to
 457          * @param int|null $rev_id The rev_id of the change to add the tags to
 458          * @param int|null $log_id The log_id of the change to add the tags to
 459          * @param string $params Params to put in the ct_params field of table
 460          * 'change_tag' when adding tags
 461          * @param User $user Who to give credit for the action
 462          * @return Status
 463          * @since 1.25
 464          */
 465         public static function addTagsAccompanyingChangeWithChecks(
 466                 array $tags, $rc_id, $rev_id, $log_id, $params, User $user
 467         ) {
 468
 469                 // are we allowed to do this?
 470                 $result = self::canAddTagsAccompanyingChange( $tags, $user );
 471                 if ( !$result->isOK() ) {
 472                         $result->value = null;
 473                         return $result;
 474                 }
 475
 476                 // do it!
 477                 self::addTags( $tags, $rc_id, $rev_id, $log_id, $params );
 478
 479                 return Status::newGood( true );
 480         }
 481
 482         /**
 483          * Is it OK to allow the user to adds and remove the given tags tags to/from a
 484          * change?
 485          *
 486          * @param array $tagsToAdd Tags that you are interested in adding
 487          * @param array $tagsToRemove Tags that you are interested in removing
 488          * @param User|null $user User whose permission you wish to check, or null if
 489          * you don't care (e.g. maintenance scripts)
 490          * @return Status
 491          * @since 1.25
 492          */
 493         public static function canUpdateTags( array $tagsToAdd, array $tagsToRemove,
 494                 User $user = null ) {
 495
 496                 if ( !is_null( $user ) ) {
 497                         if ( !$user->isAllowed( 'changetags' ) ) {
 498                                 return Status::newFatal( 'tags-update-no-permission' );
 499                         } elseif ( $user->isBlocked() ) {
 500                                 return Status::newFatal( 'tags-update-blocked', $user->getName() );
 501                         }
 502                 }
 503
 504                 if ( $tagsToAdd ) {
 505                         // to be added, a tag has to be explicitly defined
 506                         // @todo Allow extensions to define tags that can be applied by users...
 507                         $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
 508                         $diff = array_diff( $tagsToAdd, $explicitlyDefinedTags );
 509                         if ( $diff ) {
 510                                 return self::restrictedTagError( 'tags-update-add-not-allowed-one',
 511                                         'tags-update-add-not-allowed-multi', $diff );
 512                         }
 513                 }
 514
 515                 if ( $tagsToRemove ) {
 516                         // to be removed, a tag must not be defined by an extension, or equivalently it
 517                         // has to be either explicitly defined or not defined at all
 518                         // (assuming no edge case of a tag both explicitly-defined and extension-defined)
 519                         $softwareDefinedTags = self::listSoftwareDefinedTags();
 520                         $intersect = array_intersect( $tagsToRemove, $softwareDefinedTags );
 521                         if ( $intersect ) {
 522                                 return self::restrictedTagError( 'tags-update-remove-not-allowed-one',
 523                                         'tags-update-remove-not-allowed-multi', $intersect );
 524                         }
 525                 }
 526
 527                 return Status::newGood();
 528         }
 529
 530         /**
 531          * Adds and/or removes tags to/from a given change, checking whether it is
 532          * allowed first, and adding a log entry afterwards.
 533          *
 534          * Includes a call to ChangeTag::canUpdateTags(), so your code doesn't need
 535          * to do that. However, it doesn't check whether the *_id parameters are a
 536          * valid combination. That is up to you to enforce. See ApiTag::execute() for
 537          * an example.
 538          *
 539          * @param array|null $tagsToAdd If none, pass array() or null
 540          * @param array|null $tagsToRemove If none, pass array() or null
 541          * @param int|null $rc_id The rc_id of the change to add the tags to
 542          * @param int|null $rev_id The rev_id of the change to add the tags to
 543          * @param int|null $log_id The log_id of the change to add the tags to
 544          * @param string $params Params to put in the ct_params field of table
 545          * 'change_tag' when adding tags
 546          * @param string $reason Comment for the log
 547          * @param User $user Who to give credit for the action
 548          * @return Status If successful, the value of this Status object will be an
 549          * object (stdClass) with the following fields:
 550          *  - logId: the ID of the added log entry, or null if no log entry was added
 551          *    (i.e. no operation was performed)
 552          *  - addedTags: an array containing the tags that were actually added
 553          *  - removedTags: an array containing the tags that were actually removed
 554          * @since 1.25
 555          */
 556         public static function updateTagsWithChecks( $tagsToAdd, $tagsToRemove,
 557                 $rc_id, $rev_id, $log_id, $params, $reason, User $user ) {
 558
 559                 if ( is_null( $tagsToAdd ) ) {
 560                         $tagsToAdd = [];
 561                 }
 562                 if ( is_null( $tagsToRemove ) ) {
 563                         $tagsToRemove = [];
 564                 }
 565                 if ( !$tagsToAdd && !$tagsToRemove ) {
 566                         // no-op, don't bother
 567                         return Status::newGood( (object)[
 568                                 'logId' => null,
 569                                 'addedTags' => [],
 570                                 'removedTags' => [],
 571                         ] );
 572                 }
 573
 574                 // are we allowed to do this?
 575                 $result = self::canUpdateTags( $tagsToAdd, $tagsToRemove, $user );
 576                 if ( !$result->isOK() ) {
 577                         $result->value = null;
 578                         return $result;
 579                 }
 580
 581                 // basic rate limiting
 582                 if ( $user->pingLimiter( 'changetag' ) ) {
 583                         return Status::newFatal( 'actionthrottledtext' );
 584                 }
 585
 586                 // do it!
 587                 list( $tagsAdded, $tagsRemoved, $initialTags ) = self::updateTags( $tagsToAdd,
 588                         $tagsToRemove, $rc_id, $rev_id, $log_id, $params, null, $user );
 589                 if ( !$tagsAdded && !$tagsRemoved ) {
 590                         // no-op, don't log it
 591                         return Status::newGood( (object)[
 592                                 'logId' => null,
 593                                 'addedTags' => [],
 594                                 'removedTags' => [],
 595                         ] );
 596                 }
 597
 598                 // log it
 599                 $logEntry = new ManualLogEntry( 'tag', 'update' );
 600                 $logEntry->setPerformer( $user );
 601                 $logEntry->setComment( $reason );
 602
 603                 // find the appropriate target page
 604                 if ( $rev_id ) {
 605                         $rev = Revision::newFromId( $rev_id );
 606                         if ( $rev ) {
 607                                 $logEntry->setTarget( $rev->getTitle() );
 608                         }
 609                 } elseif ( $log_id ) {
 610                         // This function is from revision deletion logic and has nothing to do with
 611                         // change tags, but it appears to be the only other place in core where we
 612                         // perform logged actions on log items.
 613                         $logEntry->setTarget( RevDelLogList::suggestTarget( null, [ $log_id ] ) );
 614                 }
 615
 616                 if ( !$logEntry->getTarget() ) {
 617                         // target is required, so we have to set something
 618                         $logEntry->setTarget( SpecialPage::getTitleFor( 'Tags' ) );
 619                 }
 620
 621                 $logParams = [
 622                         '4::revid' => $rev_id,
 623                         '5::logid' => $log_id,
 624                         '6:list:tagsAdded' => $tagsAdded,
 625                         '7:number:tagsAddedCount' => count( $tagsAdded ),
 626                         '8:list:tagsRemoved' => $tagsRemoved,
 627                         '9:number:tagsRemovedCount' => count( $tagsRemoved ),
 628                         'initialTags' => $initialTags,
 629                 ];
 630                 $logEntry->setParameters( $logParams );
 631                 $logEntry->setRelations( [ 'Tag' => array_merge( $tagsAdded, $tagsRemoved ) ] );
 632
 633                 $dbw = wfGetDB( DB_MASTER );
 634                 $logId = $logEntry->insert( $dbw );
 635                 // Only send this to UDP, not RC, similar to patrol events
 636                 $logEntry->publish( $logId, 'udp' );
 637
 638                 return Status::newGood( (object)[
 639                         'logId' => $logId,
 640                         'addedTags' => $tagsAdded,
 641                         'removedTags' => $tagsRemoved,
 642                 ] );
 643         }
 644
 645         /**
 646          * Applies all tags-related changes to a query.
 647          * Handles selecting tags, and filtering.
 648          * Needs $tables to be set up properly, so we can figure out which join conditions to use.
 649          *
 650          * @param string|array $tables Table names, see Database::select
 651          * @param string|array $fields Fields used in query, see Database::select
 652          * @param string|array $conds Conditions used in query, see Database::select
 653          * @param array $join_conds Join conditions, see Database::select
 654          * @param array $options Options, see Database::select
 655          * @param bool|string $filter_tag Tag to select on
 656          *
 657          * @throws MWException When unable to determine appropriate JOIN condition for tagging
 658          */
 659         public static function modifyDisplayQuery( &$tables, &$fields, &$conds,
 660                                                                                 &$join_conds, &$options, $filter_tag = false ) {
 661                 global $wgRequest, $wgUseTagFilter;
 662
 663                 if ( $filter_tag === false ) {
 664                         $filter_tag = $wgRequest->getVal( 'tagfilter' );
 665                 }
 666
 667                 // Figure out which conditions can be done.
 668                 if ( in_array( 'recentchanges', $tables ) ) {
 669                         $join_cond = 'ct_rc_id=rc_id';
 670                 } elseif ( in_array( 'logging', $tables ) ) {
 671                         $join_cond = 'ct_log_id=log_id';
 672                 } elseif ( in_array( 'revision', $tables ) ) {
 673                         $join_cond = 'ct_rev_id=rev_id';
 674                 } elseif ( in_array( 'archive', $tables ) ) {
 675                         $join_cond = 'ct_rev_id=ar_rev_id';
 676                 } else {
 677                         throw new MWException( 'Unable to determine appropriate JOIN condition for tagging.' );
 678                 }
 679
 680                 $fields['ts_tags'] = wfGetDB( DB_REPLICA )->buildGroupConcatField(
 681                         ',', 'change_tag', 'ct_tag', $join_cond
 682                 );
 683
 684                 if ( $wgUseTagFilter && $filter_tag ) {
 685                         // Somebody wants to filter on a tag.
 686                         // Add an INNER JOIN on change_tag
 687
 688                         $tables[] = 'change_tag';
 689                         $join_conds['change_tag'] = [ 'INNER JOIN', $join_cond ];
 690                         $conds['ct_tag'] = explode( '|', $filter_tag );
 691                 }
 692         }
 693
 694         /**
 695          * Build a text box to select a change tag
 696          *
 697          * @param string $selected Tag to select by default
 698          * @param bool $ooui Use an OOUI TextInputWidget as selector instead of a non-OOUI input field
 699          *        You need to call OutputPage::enableOOUI() yourself.
 700          * @param IContextSource|null $context
 701          * @note Even though it takes null as a valid argument, an IContextSource is preferred
 702          *       in a new code, as the null value can change in the future
 703          * @return array an array of (label, selector)
 704          */
 705         public static function buildTagFilterSelector(
 706                 $selected = '', $ooui = false, IContextSource $context = null
 707         ) {
 708                 if ( !$context ) {
 709                         $context = RequestContext::getMain();
 710                 }
 711
 712                 $config = $context->getConfig();
 713                 if ( !$config->get( 'UseTagFilter' ) || !count( self::listDefinedTags() ) ) {
 714                         return [];
 715                 }
 716
 717                 $data = [
 718                         Html::rawElement(
 719                                 'label',
 720                                 [ 'for' => 'tagfilter' ],
 721                                 $context->msg( 'tag-filter' )->parse()
 722                         )
 723                 ];
 724
 725                 if ( $ooui ) {
 726                         $data[] = new OOUI\TextInputWidget( [
 727                                 'id' => 'tagfilter',
 728                                 'name' => 'tagfilter',
 729                                 'value' => $selected,
 730                                 'classes' => 'mw-tagfilter-input',
 731                         ] );
 732                 } else {
 733                         $data[] = Xml::input(
 734                                 'tagfilter',
 735                                 20,
 736                                 $selected,
 737                                 [ 'class' => 'mw-tagfilter-input mw-ui-input mw-ui-input-inline', 'id' => 'tagfilter' ]
 738                         );
 739                 }
 740
 741                 return $data;
 742         }
 743
 744         /**
 745          * Defines a tag in the valid_tag table, without checking that the tag name
 746          * is valid.
 747          * Extensions should NOT use this function; they can use the ListDefinedTags
 748          * hook instead.
 749          *
 750          * @param string $tag Tag to create
 751          * @since 1.25
 752          */
 753         public static function defineTag( $tag ) {
 754                 $dbw = wfGetDB( DB_MASTER );
 755                 $dbw->replace( 'valid_tag',
 756                         [ 'vt_tag' ],
 757                         [ 'vt_tag' => $tag ],
 758                         __METHOD__ );
 759
 760                 // clear the memcache of defined tags
 761                 self::purgeTagCacheAll();
 762         }
 763
 764         /**
 765          * Removes a tag from the valid_tag table. The tag may remain in use by
 766          * extensions, and may still show up as 'defined' if an extension is setting
 767          * it from the ListDefinedTags hook.
 768          *
 769          * @param string $tag Tag to remove
 770          * @since 1.25
 771          */
 772         public static function undefineTag( $tag ) {
 773                 $dbw = wfGetDB( DB_MASTER );
 774                 $dbw->delete( 'valid_tag', [ 'vt_tag' => $tag ], __METHOD__ );
 775
 776                 // clear the memcache of defined tags
 777                 self::purgeTagCacheAll();
 778         }
 779
 780         /**
 781          * Writes a tag action into the tag management log.
 782          *
 783          * @param string $action
 784          * @param string $tag
 785          * @param string $reason
 786          * @param User $user Who to attribute the action to
 787          * @param int $tagCount For deletion only, how many usages the tag had before
 788          * it was deleted.
 789          * @param array $logEntryTags Change tags to apply to the entry
 790          * that will be created in the tag management log
 791          * @return int ID of the inserted log entry
 792          * @since 1.25
 793          */
 794         protected static function logTagManagementAction( $action, $tag, $reason,
 795                 User $user, $tagCount = null, array $logEntryTags = [] ) {
 796
 797                 $dbw = wfGetDB( DB_MASTER );
 798
 799                 $logEntry = new ManualLogEntry( 'managetags', $action );
 800                 $logEntry->setPerformer( $user );
 801                 // target page is not relevant, but it has to be set, so we just put in
 802                 // the title of Special:Tags
 803                 $logEntry->setTarget( Title::newFromText( 'Special:Tags' ) );
 804                 $logEntry->setComment( $reason );
 805
 806                 $params = [ '4::tag' => $tag ];
 807                 if ( !is_null( $tagCount ) ) {
 808                         $params['5:number:count'] = $tagCount;
 809                 }
 810                 $logEntry->setParameters( $params );
 811                 $logEntry->setRelations( [ 'Tag' => $tag ] );
 812                 $logEntry->setTags( $logEntryTags );
 813
 814                 $logId = $logEntry->insert( $dbw );
 815                 $logEntry->publish( $logId );
 816                 return $logId;
 817         }
 818
 819         /**
 820          * Is it OK to allow the user to activate this tag?
 821          *
 822          * @param string $tag Tag that you are interested in activating
 823          * @param User|null $user User whose permission you wish to check, or null if
 824          * you don't care (e.g. maintenance scripts)
 825          * @return Status
 826          * @since 1.25
 827          */
 828         public static function canActivateTag( $tag, User $user = null ) {
 829                 if ( !is_null( $user ) ) {
 830                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 831                                 return Status::newFatal( 'tags-manage-no-permission' );
 832                         } elseif ( $user->isBlocked() ) {
 833                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
 834                         }
 835                 }
 836
 837                 // defined tags cannot be activated (a defined tag is either extension-
 838                 // defined, in which case the extension chooses whether or not to active it;
 839                 // or user-defined, in which case it is considered active)
 840                 $definedTags = self::listDefinedTags();
 841                 if ( in_array( $tag, $definedTags ) ) {
 842                         return Status::newFatal( 'tags-activate-not-allowed', $tag );
 843                 }
 844
 845                 // non-existing tags cannot be activated
 846                 $tagUsage = self::tagUsageStatistics();
 847                 if ( !isset( $tagUsage[$tag] ) ) { // we already know the tag is undefined
 848                         return Status::newFatal( 'tags-activate-not-found', $tag );
 849                 }
 850
 851                 return Status::newGood();
 852         }
 853
 854         /**
 855          * Activates a tag, checking whether it is allowed first, and adding a log
 856          * entry afterwards.
 857          *
 858          * Includes a call to ChangeTag::canActivateTag(), so your code doesn't need
 859          * to do that.
 860          *
 861          * @param string $tag
 862          * @param string $reason
 863          * @param User $user Who to give credit for the action
 864          * @param bool $ignoreWarnings Can be used for API interaction, default false
 865          * @param array $logEntryTags Change tags to apply to the entry
 866          * that will be created in the tag management log
 867          * @return Status If successful, the Status contains the ID of the added log
 868          * entry as its value
 869          * @since 1.25
 870          */
 871         public static function activateTagWithChecks( $tag, $reason, User $user,
 872                 $ignoreWarnings = false, array $logEntryTags = [] ) {
 873
 874                 // are we allowed to do this?
 875                 $result = self::canActivateTag( $tag, $user );
 876                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
 877                         $result->value = null;
 878                         return $result;
 879                 }
 880
 881                 // do it!
 882                 self::defineTag( $tag );
 883
 884                 // log it
 885                 $logId = self::logTagManagementAction( 'activate', $tag, $reason, $user,
 886                         null, $logEntryTags );
 887
 888                 return Status::newGood( $logId );
 889         }
 890
 891         /**
 892          * Is it OK to allow the user to deactivate this tag?
 893          *
 894          * @param string $tag Tag that you are interested in deactivating
 895          * @param User|null $user User whose permission you wish to check, or null if
 896          * you don't care (e.g. maintenance scripts)
 897          * @return Status
 898          * @since 1.25
 899          */
 900         public static function canDeactivateTag( $tag, User $user = null ) {
 901                 if ( !is_null( $user ) ) {
 902                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 903                                 return Status::newFatal( 'tags-manage-no-permission' );
 904                         } elseif ( $user->isBlocked() ) {
 905                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
 906                         }
 907                 }
 908
 909                 // only explicitly-defined tags can be deactivated
 910                 $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
 911                 if ( !in_array( $tag, $explicitlyDefinedTags ) ) {
 912                         return Status::newFatal( 'tags-deactivate-not-allowed', $tag );
 913                 }
 914                 return Status::newGood();
 915         }
 916
 917         /**
 918          * Deactivates a tag, checking whether it is allowed first, and adding a log
 919          * entry afterwards.
 920          *
 921          * Includes a call to ChangeTag::canDeactivateTag(), so your code doesn't need
 922          * to do that.
 923          *
 924          * @param string $tag
 925          * @param string $reason
 926          * @param User $user Who to give credit for the action
 927          * @param bool $ignoreWarnings Can be used for API interaction, default false
 928          * @param array $logEntryTags Change tags to apply to the entry
 929          * that will be created in the tag management log
 930          * @return Status If successful, the Status contains the ID of the added log
 931          * entry as its value
 932          * @since 1.25
 933          */
 934         public static function deactivateTagWithChecks( $tag, $reason, User $user,
 935                 $ignoreWarnings = false, array $logEntryTags = [] ) {
 936
 937                 // are we allowed to do this?
 938                 $result = self::canDeactivateTag( $tag, $user );
 939                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
 940                         $result->value = null;
 941                         return $result;
 942                 }
 943
 944                 // do it!
 945                 self::undefineTag( $tag );
 946
 947                 // log it
 948                 $logId = self::logTagManagementAction( 'deactivate', $tag, $reason, $user,
 949                         null, $logEntryTags );
 950
 951                 return Status::newGood( $logId );
 952         }
 953
 954         /**
 955          * Is the tag name valid?
 956          *
 957          * @param string $tag Tag that you are interested in creating
 958          * @return Status
 959          * @since 1.30
 960          */
 961         public static function isTagNameValid( $tag ) {
 962                 // no empty tags
 963                 if ( $tag === '' ) {
 964                         return Status::newFatal( 'tags-create-no-name' );
 965                 }
 966
 967                 // tags cannot contain commas (used as a delimiter in tag_summary table),
 968                 // pipe (used as a delimiter between multiple tags in
 969                 // modifyDisplayQuery), or slashes (would break tag description messages in
 970                 // MediaWiki namespace)
 971                 if ( strpos( $tag, ',' ) !== false || strpos( $tag, '|' ) !== false
 972                         || strpos( $tag, '/' ) !== false ) {
 973                         return Status::newFatal( 'tags-create-invalid-chars' );
 974                 }
 975
 976                 // could the MediaWiki namespace description messages be created?
 977                 $title = Title::makeTitleSafe( NS_MEDIAWIKI, "Tag-$tag-description" );
 978                 if ( is_null( $title ) ) {
 979                         return Status::newFatal( 'tags-create-invalid-title-chars' );
 980                 }
 981
 982                 return Status::newGood();
 983         }
 984
 985         /**
 986          * Is it OK to allow the user to create this tag?
 987          *
 988          * @param string $tag Tag that you are interested in creating
 989          * @param User|null $user User whose permission you wish to check, or null if
 990          * you don't care (e.g. maintenance scripts)
 991          * @return Status
 992          * @since 1.25
 993          */
 994         public static function canCreateTag( $tag, User $user = null ) {
 995                 if ( !is_null( $user ) ) {
 996                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 997                                 return Status::newFatal( 'tags-manage-no-permission' );
 998                         } elseif ( $user->isBlocked() ) {
 999                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1000                         }
1001                 }
1002
1003                 $status = self::isTagNameValid( $tag );
1004                 if ( !$status->isGood() ) {
1005                         return $status;
1006                 }
1007
1008                 // does the tag already exist?
1009                 $tagUsage = self::tagUsageStatistics();
1010                 if ( isset( $tagUsage[$tag] ) || in_array( $tag, self::listDefinedTags() ) ) {
1011                         return Status::newFatal( 'tags-create-already-exists', $tag );
1012                 }
1013
1014                 // check with hooks
1015                 $canCreateResult = Status::newGood();
1016                 Hooks::run( 'ChangeTagCanCreate', [ $tag, $user, &$canCreateResult ] );
1017                 return $canCreateResult;
1018         }
1019
1020         /**
1021          * Creates a tag by adding a row to the `valid_tag` table.
1022          *
1023          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
1024          * do that.
1025          *
1026          * @param string $tag
1027          * @param string $reason
1028          * @param User $user Who to give credit for the action
1029          * @param bool $ignoreWarnings Can be used for API interaction, default false
1030          * @param array $logEntryTags Change tags to apply to the entry
1031          * that will be created in the tag management log
1032          * @return Status If successful, the Status contains the ID of the added log
1033          * entry as its value
1034          * @since 1.25
1035          */
1036         public static function createTagWithChecks( $tag, $reason, User $user,
1037                 $ignoreWarnings = false, array $logEntryTags = [] ) {
1038
1039                 // are we allowed to do this?
1040                 $result = self::canCreateTag( $tag, $user );
1041                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1042                         $result->value = null;
1043                         return $result;
1044                 }
1045
1046                 // do it!
1047                 self::defineTag( $tag );
1048
1049                 // log it
1050                 $logId = self::logTagManagementAction( 'create', $tag, $reason, $user,
1051                         null, $logEntryTags );
1052
1053                 return Status::newGood( $logId );
1054         }
1055
1056         /**
1057          * Permanently removes all traces of a tag from the DB. Good for removing
1058          * misspelt or temporary tags.
1059          *
1060          * This function should be directly called by maintenance scripts only, never
1061          * by user-facing code. See deleteTagWithChecks() for functionality that can
1062          * safely be exposed to users.
1063          *
1064          * @param string $tag Tag to remove
1065          * @return Status The returned status will be good unless a hook changed it
1066          * @since 1.25
1067          */
1068         public static function deleteTagEverywhere( $tag ) {
1069                 $dbw = wfGetDB( DB_MASTER );
1070                 $dbw->startAtomic( __METHOD__ );
1071
1072                 // delete from valid_tag
1073                 self::undefineTag( $tag );
1074
1075                 // find out which revisions use this tag, so we can delete from tag_summary
1076                 $result = $dbw->select( 'change_tag',
1077                         [ 'ct_rc_id', 'ct_log_id', 'ct_rev_id', 'ct_tag' ],
1078                         [ 'ct_tag' => $tag ],
1079                         __METHOD__ );
1080                 foreach ( $result as $row ) {
1081                         // remove the tag from the relevant row of tag_summary
1082                         $tagsToAdd = [];
1083                         $tagsToRemove = [ $tag ];
1084                         self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $row->ct_rc_id,
1085                                 $row->ct_rev_id, $row->ct_log_id );
1086                 }
1087
1088                 // delete from change_tag
1089                 $dbw->delete( 'change_tag', [ 'ct_tag' => $tag ], __METHOD__ );
1090
1091                 $dbw->endAtomic( __METHOD__ );
1092
1093                 // give extensions a chance
1094                 $status = Status::newGood();
1095                 Hooks::run( 'ChangeTagAfterDelete', [ $tag, &$status ] );
1096                 // let's not allow error results, as the actual tag deletion succeeded
1097                 if ( !$status->isOK() ) {
1098                         wfDebug( 'ChangeTagAfterDelete error condition downgraded to warning' );
1099                         $status->setOK( true );
1100                 }
1101
1102                 // clear the memcache of defined tags
1103                 self::purgeTagCacheAll();
1104
1105                 return $status;
1106         }
1107
1108         /**
1109          * Is it OK to allow the user to delete this tag?
1110          *
1111          * @param string $tag Tag that you are interested in deleting
1112          * @param User|null $user User whose permission you wish to check, or null if
1113          * you don't care (e.g. maintenance scripts)
1114          * @return Status
1115          * @since 1.25
1116          */
1117         public static function canDeleteTag( $tag, User $user = null ) {
1118                 $tagUsage = self::tagUsageStatistics();
1119
1120                 if ( !is_null( $user ) ) {
1121                         if ( !$user->isAllowed( 'deletechangetags' ) ) {
1122                                 return Status::newFatal( 'tags-delete-no-permission' );
1123                         } elseif ( $user->isBlocked() ) {
1124                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1125                         }
1126                 }
1127
1128                 if ( !isset( $tagUsage[$tag] ) && !in_array( $tag, self::listDefinedTags() ) ) {
1129                         return Status::newFatal( 'tags-delete-not-found', $tag );
1130                 }
1131
1132                 if ( isset( $tagUsage[$tag] ) && $tagUsage[$tag] > self::MAX_DELETE_USES ) {
1133                         return Status::newFatal( 'tags-delete-too-many-uses', $tag, self::MAX_DELETE_USES );
1134                 }
1135
1136                 $softwareDefined = self::listSoftwareDefinedTags();
1137                 if ( in_array( $tag, $softwareDefined ) ) {
1138                         // extension-defined tags can't be deleted unless the extension
1139                         // specifically allows it
1140                         $status = Status::newFatal( 'tags-delete-not-allowed' );
1141                 } else {
1142                         // user-defined tags are deletable unless otherwise specified
1143                         $status = Status::newGood();
1144                 }
1145
1146                 Hooks::run( 'ChangeTagCanDelete', [ $tag, $user, &$status ] );
1147                 return $status;
1148         }
1149
1150         /**
1151          * Deletes a tag, checking whether it is allowed first, and adding a log entry
1152          * afterwards.
1153          *
1154          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
1155          * do that.
1156          *
1157          * @param string $tag
1158          * @param string $reason
1159          * @param User $user Who to give credit for the action
1160          * @param bool $ignoreWarnings Can be used for API interaction, default false
1161          * @param array $logEntryTags Change tags to apply to the entry
1162          * that will be created in the tag management log
1163          * @return Status If successful, the Status contains the ID of the added log
1164          * entry as its value
1165          * @since 1.25
1166          */
1167         public static function deleteTagWithChecks( $tag, $reason, User $user,
1168                 $ignoreWarnings = false, array $logEntryTags = [] ) {
1169
1170                 // are we allowed to do this?
1171                 $result = self::canDeleteTag( $tag, $user );
1172                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1173                         $result->value = null;
1174                         return $result;
1175                 }
1176
1177                 // store the tag usage statistics
1178                 $tagUsage = self::tagUsageStatistics();
1179                 $hitcount = isset( $tagUsage[$tag] ) ? $tagUsage[$tag] : 0;
1180
1181                 // do it!
1182                 $deleteResult = self::deleteTagEverywhere( $tag );
1183                 if ( !$deleteResult->isOK() ) {
1184                         return $deleteResult;
1185                 }
1186
1187                 // log it
1188                 $logId = self::logTagManagementAction( 'delete', $tag, $reason, $user,
1189                         $hitcount, $logEntryTags );
1190
1191                 $deleteResult->value = $logId;
1192                 return $deleteResult;
1193         }
1194
1195         /**
1196          * Lists those tags which core or extensions report as being "active".
1197          *
1198          * @return array
1199          * @since 1.25
1200          */
1201         public static function listSoftwareActivatedTags() {
1202                 // core active tags
1203                 $tags = self::$coreTags;
1204                 if ( !Hooks::isRegistered( 'ChangeTagsListActive' ) ) {
1205                         return $tags;
1206                 }
1207                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1208                 return $cache->getWithSetCallback(
1209                         $cache->makeKey( 'active-tags' ),
1210                         WANObjectCache::TTL_MINUTE * 5,
1211                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1212                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1213
1214                                 // Ask extensions which tags they consider active
1215                                 Hooks::run( 'ChangeTagsListActive', [ &$tags ] );
1216                                 return $tags;
1217                         },
1218                         [
1219                                 'checkKeys' => [ $cache->makeKey( 'active-tags' ) ],
1220                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1221                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1222                         ]
1223                 );
1224         }
1225
1226         /**
1227          * @see listSoftwareActivatedTags
1228          * @deprecated since 1.28 call listSoftwareActivatedTags directly
1229          * @return array
1230          */
1231         public static function listExtensionActivatedTags() {
1232                 wfDeprecated( __METHOD__, '1.28' );
1233                 return self::listSoftwareActivatedTags();
1234         }
1235
1236         /**
1237          * Basically lists defined tags which count even if they aren't applied to anything.
1238          * It returns a union of the results of listExplicitlyDefinedTags() and
1239          * listExtensionDefinedTags().
1240          *
1241          * @return string[] Array of strings: tags
1242          */
1243         public static function listDefinedTags() {
1244                 $tags1 = self::listExplicitlyDefinedTags();
1245                 $tags2 = self::listSoftwareDefinedTags();
1246                 return array_values( array_unique( array_merge( $tags1, $tags2 ) ) );
1247         }
1248
1249         /**
1250          * Lists tags explicitly defined in the `valid_tag` table of the database.
1251          * Tags in table 'change_tag' which are not in table 'valid_tag' are not
1252          * included.
1253          *
1254          * Tries memcached first.
1255          *
1256          * @return string[] Array of strings: tags
1257          * @since 1.25
1258          */
1259         public static function listExplicitlyDefinedTags() {
1260                 $fname = __METHOD__;
1261
1262                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1263                 return $cache->getWithSetCallback(
1264                         $cache->makeKey( 'valid-tags-db' ),
1265                         WANObjectCache::TTL_MINUTE * 5,
1266                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1267                                 $dbr = wfGetDB( DB_REPLICA );
1268
1269                                 $setOpts += Database::getCacheSetOptions( $dbr );
1270
1271                                 $tags = $dbr->selectFieldValues( 'valid_tag', 'vt_tag', [], $fname );
1272
1273                                 return array_filter( array_unique( $tags ) );
1274                         },
1275                         [
1276                                 'checkKeys' => [ $cache->makeKey( 'valid-tags-db' ) ],
1277                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1278                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1279                         ]
1280                 );
1281         }
1282
1283         /**
1284          * Lists tags defined by core or extensions using the ListDefinedTags hook.
1285          * Extensions need only define those tags they deem to be in active use.
1286          *
1287          * Tries memcached first.
1288          *
1289          * @return string[] Array of strings: tags
1290          * @since 1.25
1291          */
1292         public static function listSoftwareDefinedTags() {
1293                 // core defined tags
1294                 $tags = self::$coreTags;
1295                 if ( !Hooks::isRegistered( 'ListDefinedTags' ) ) {
1296                         return $tags;
1297                 }
1298                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1299                 return $cache->getWithSetCallback(
1300                         $cache->makeKey( 'valid-tags-hook' ),
1301                         WANObjectCache::TTL_MINUTE * 5,
1302                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1303                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1304
1305                                 Hooks::run( 'ListDefinedTags', [ &$tags ] );
1306                                 return array_filter( array_unique( $tags ) );
1307                         },
1308                         [
1309                                 'checkKeys' => [ $cache->makeKey( 'valid-tags-hook' ) ],
1310                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1311                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1312                         ]
1313                 );
1314         }
1315
1316         /**
1317          * Call listSoftwareDefinedTags directly
1318          *
1319          * @see listSoftwareDefinedTags
1320          * @deprecated since 1.28
1321          */
1322         public static function listExtensionDefinedTags() {
1323                 wfDeprecated( __METHOD__, '1.28' );
1324                 return self::listSoftwareDefinedTags();
1325         }
1326
1327         /**
1328          * Invalidates the short-term cache of defined tags used by the
1329          * list*DefinedTags functions, as well as the tag statistics cache.
1330          * @since 1.25
1331          */
1332         public static function purgeTagCacheAll() {
1333                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1334
1335                 $cache->touchCheckKey( $cache->makeKey( 'active-tags' ) );
1336                 $cache->touchCheckKey( $cache->makeKey( 'valid-tags-db' ) );
1337                 $cache->touchCheckKey( $cache->makeKey( 'valid-tags-hook' ) );
1338
1339                 self::purgeTagUsageCache();
1340         }
1341
1342         /**
1343          * Invalidates the tag statistics cache only.
1344          * @since 1.25
1345          */
1346         public static function purgeTagUsageCache() {
1347                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1348
1349                 $cache->touchCheckKey( $cache->makeKey( 'change-tag-statistics' ) );
1350         }
1351
1352         /**
1353          * Returns a map of any tags used on the wiki to number of edits
1354          * tagged with them, ordered descending by the hitcount.
1355          * This does not include tags defined somewhere that have never been applied.
1356          *
1357          * Keeps a short-term cache in memory, so calling this multiple times in the
1358          * same request should be fine.
1359          *
1360          * @return array Array of string => int
1361          */
1362         public static function tagUsageStatistics() {
1363                 $fname = __METHOD__;
1364                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1365                 return $cache->getWithSetCallback(
1366                         $cache->makeKey( 'change-tag-statistics' ),
1367                         WANObjectCache::TTL_MINUTE * 5,
1368                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1369                                 $dbr = wfGetDB( DB_REPLICA, 'vslow' );
1370
1371                                 $setOpts += Database::getCacheSetOptions( $dbr );
1372
1373                                 $res = $dbr->select(
1374                                         'change_tag',
1375                                         [ 'ct_tag', 'hitcount' => 'count(*)' ],
1376                                         [],
1377                                         $fname,
1378                                         [ 'GROUP BY' => 'ct_tag', 'ORDER BY' => 'hitcount DESC' ]
1379                                 );
1380
1381                                 $out = [];
1382                                 foreach ( $res as $row ) {
1383                                         $out[$row->ct_tag] = $row->hitcount;
1384                                 }
1385
1386                                 return $out;
1387                         },
1388                         [
1389                                 'checkKeys' => [ $cache->makeKey( 'change-tag-statistics' ) ],
1390                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1391                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1392                         ]
1393                 );
1394         }
1395
1396         /**
1397          * Indicate whether change tag editing UI is relevant
1398          *
1399          * Returns true if the user has the necessary right and there are any
1400          * editable tags defined.
1401          *
1402          * This intentionally doesn't check "any addable || any deletable", because
1403          * it seems like it would be more confusing than useful if the checkboxes
1404          * suddenly showed up because some abuse filter stopped defining a tag and
1405          * then suddenly disappeared when someone deleted all uses of that tag.
1406          *
1407          * @param User $user
1408          * @return bool
1409          */
1410         public static function showTagEditingUI( User $user ) {
1411                 return $user->isAllowed( 'changetags' ) && (bool)self::listExplicitlyDefinedTags();
1412         }
1413 }