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 216                         // Info might be out of date, somewhat fractionally, on replica DB.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 243                         // Info might be out of date, somewhat fractionally, on replica DB.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