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 MediaWiki\Storage\NameTableAccessException;
  26 use Wikimedia\Rdbms\Database;
  27
  28 class ChangeTags {
  29         /**
  30          * Can't delete tags with more than this many uses. Similar in intent to
  31          * the bigdelete user right
  32          * @todo Use the job queue for tag deletion to avoid this restriction
  33          */
  34         const MAX_DELETE_USES = 5000;
  35
  36         /**
  37          * A list of tags defined and used by MediaWiki itself.
  38          */
  39         private static $definedSoftwareTags = [
  40                 'mw-contentmodelchange',
  41                 'mw-new-redirect',
  42                 'mw-removed-redirect',
  43                 'mw-changed-redirect-target',
  44                 'mw-blank',
  45                 'mw-replace',
  46                 'mw-rollback',
  47                 'mw-undo',
  48         ];
  49
  50         /**
  51          * Loads defined core tags, checks for invalid types (if not array),
  52          * and filters for supported and enabled (if $all is false) tags only.
  53          *
  54          * @param bool $all If true, return all valid defined tags. Otherwise, return only enabled ones.
  55          * @return array Array of all defined/enabled tags.
  56          */
  57         public static function getSoftwareTags( $all = false ) {
  58                 global $wgSoftwareTags;
  59                 $softwareTags = [];
  60
  61                 if ( !is_array( $wgSoftwareTags ) ) {
  62                         wfWarn( 'wgSoftwareTags should be associative array of enabled tags.
  63                         Please refer to documentation for the list of tags you can enable' );
  64                         return $softwareTags;
  65                 }
  66
  67                 $availableSoftwareTags = !$all ?
  68                         array_keys( array_filter( $wgSoftwareTags ) ) :
  69                         array_keys( $wgSoftwareTags );
  70
  71                 $softwareTags = array_intersect(
  72                         $availableSoftwareTags,
  73                         self::$definedSoftwareTags
  74                 );
  75
  76                 return $softwareTags;
  77         }
  78
  79         /**
  80          * Creates HTML for the given tags
  81          *
  82          * @param string $tags Comma-separated list of tags
  83          * @param string $page A label for the type of action which is being displayed,
  84          *   for example: 'history', 'contributions' or 'newpages'
  85          * @param IContextSource|null $context
  86          * @note Even though it takes null as a valid argument, an IContextSource is preferred
  87          *       in a new code, as the null value is subject to change in the future
  88          * @return array Array with two items: (html, classes)
  89          *   - html: String: HTML for displaying the tags (empty string when param $tags is empty)
  90          *   - classes: Array of strings: CSS classes used in the generated html, one class for each tag
  91          * @return-taint onlysafefor_htmlnoent
  92          */
  93         public static function formatSummaryRow( $tags, $page, IContextSource $context = null ) {
  94                 if ( !$tags ) {
  95                         return [ '', [] ];
  96                 }
  97                 if ( !$context ) {
  98                         $context = RequestContext::getMain();
  99                 }
 100
 101                 $classes = [];
 102
 103                 $tags = explode( ',', $tags );
 104                 $displayTags = [];
 105                 foreach ( $tags as $tag ) {
 106                         if ( !$tag ) {
 107                                 continue;
 108                         }
 109                         $description = self::tagDescription( $tag, $context );
 110                         if ( $description === false ) {
 111                                 continue;
 112                         }
 113                         $displayTags[] = Xml::tags(
 114                                 'span',
 115                                 [ 'class' => 'mw-tag-marker ' .
 116                                                                 Sanitizer::escapeClass( "mw-tag-marker-$tag" ) ],
 117                                 $description
 118                         );
 119                         $classes[] = Sanitizer::escapeClass( "mw-tag-$tag" );
 120                 }
 121
 122                 if ( !$displayTags ) {
 123                         return [ '', [] ];
 124                 }
 125
 126                 $markers = $context->msg( 'tag-list-wrapper' )
 127                         ->numParams( count( $displayTags ) )
 128                         ->rawParams( $context->getLanguage()->commaList( $displayTags ) )
 129                         ->parse();
 130                 $markers = Xml::tags( 'span', [ 'class' => 'mw-tag-markers' ], $markers );
 131
 132                 return [ $markers, $classes ];
 133         }
 134
 135         /**
 136          * Get the message object for the tag's short description.
 137          *
 138          * Checks if message key "mediawiki:tag-$tag" exists. If it does not,
 139          * returns the tag name in a RawMessage. If the message exists, it is
 140          * used, provided it is not disabled. If the message is disabled, we
 141          * consider the tag hidden, and return false.
 142          *
 143          * @since 1.34
 144          * @param string $tag
 145          * @param MessageLocalizer $context
 146          * @return Message|bool Tag description, or false if tag is to be hidden.
 147          */
 148         public static function tagShortDescriptionMessage( $tag, MessageLocalizer $context ) {
 149                 $msg = $context->msg( "tag-$tag" );
 150                 if ( !$msg->exists() ) {
 151                         // No such message
 152                         return new RawMessage( '$1', [ Message::plaintextParam( $tag ) ] );
 153                 }
 154                 if ( $msg->isDisabled() ) {
 155                         // The message exists but is disabled, hide the tag.
 156                         return false;
 157                 }
 158
 159                 // Message exists and isn't disabled, use it.
 160                 return $msg;
 161         }
 162
 163         /**
 164          * Get a short description for a tag.
 165          *
 166          * Checks if message key "mediawiki:tag-$tag" exists. If it does not,
 167          * returns the HTML-escaped tag name. Uses the message if the message
 168          * exists, provided it is not disabled. If the message is disabled,
 169          * we consider the tag hidden, and return false.
 170          *
 171          * @param string $tag
 172          * @param MessageLocalizer $context
 173          * @return string|bool Tag description or false if tag is to be hidden.
 174          * @since 1.25 Returns false if tag is to be hidden.
 175          */
 176         public static function tagDescription( $tag, MessageLocalizer $context ) {
 177                 $msg = self::tagShortDescriptionMessage( $tag, $context );
 178                 return $msg ? $msg->parse() : false;
 179         }
 180
 181         /**
 182          * Get the message object for the tag's long description.
 183          *
 184          * Checks if message key "mediawiki:tag-$tag-description" exists. If it does not,
 185          * or if message is disabled, returns false. Otherwise, returns the message object
 186          * for the long description.
 187          *
 188          * @param string $tag
 189          * @param MessageLocalizer $context
 190          * @return Message|bool Message object of the tag long description or false if
 191          *  there is no description.
 192          */
 193         public static function tagLongDescriptionMessage( $tag, MessageLocalizer $context ) {
 194                 $msg = $context->msg( "tag-$tag-description" );
 195                 if ( !$msg->exists() ) {
 196                         return false;
 197                 }
 198                 if ( $msg->isDisabled() ) {
 199                         // The message exists but is disabled, hide the description.
 200                         return false;
 201                 }
 202
 203                 // Message exists and isn't disabled, use it.
 204                 return $msg;
 205         }
 206
 207         /**
 208          * Get truncated message for the tag's long description.
 209          *
 210          * @param string $tag Tag name.
 211          * @param int $length Maximum length of truncated message, including ellipsis.
 212          * @param IContextSource $context
 213          *
 214          * @return string Truncated long tag description.
 215          */
 216         public static function truncateTagDescription( $tag, $length, IContextSource $context ) {
 217                 // FIXME: Make this accept MessageLocalizer and Language instead of IContextSource
 218
 219                 $originalDesc = self::tagLongDescriptionMessage( $tag, $context );
 220                 // If there is no tag description, return empty string
 221                 if ( !$originalDesc ) {
 222                         return '';
 223                 }
 224
 225                 $taglessDesc = Sanitizer::stripAllTags( $originalDesc->parse() );
 226
 227                 return $context->getLanguage()->truncateForVisual( $taglessDesc, $length );
 228         }
 229
 230         /**
 231          * Add tags to a change given its rc_id, rev_id and/or log_id
 232          *
 233          * @param string|string[] $tags Tags to add to the change
 234          * @param int|null $rc_id The rc_id of the change to add the tags to
 235          * @param int|null $rev_id The rev_id of the change to add the tags to
 236          * @param int|null $log_id The log_id of the change to add the tags to
 237          * @param string|null $params Params to put in the ct_params field of table 'change_tag'
 238          * @param RecentChange|null $rc Recent change, in case the tagging accompanies the action
 239          * (this should normally be the case)
 240          *
 241          * @throws MWException
 242          * @return bool False if no changes are made, otherwise true
 243          */
 244         public static function addTags( $tags, $rc_id = null, $rev_id = null,
 245                 $log_id = null, $params = null, RecentChange $rc = null
 246         ) {
 247                 $result = self::updateTags( $tags, null, $rc_id, $rev_id, $log_id, $params, $rc );
 248                 return (bool)$result[0];
 249         }
 250
 251         /**
 252          * Add and remove tags to/from a change given its rc_id, rev_id and/or log_id,
 253          * without verifying that the tags exist or are valid. If a tag is present in
 254          * both $tagsToAdd and $tagsToRemove, it will be removed.
 255          *
 256          * This function should only be used by extensions to manipulate tags they
 257          * have registered using the ListDefinedTags hook. When dealing with user
 258          * input, call updateTagsWithChecks() instead.
 259          *
 260          * @param string|array|null $tagsToAdd Tags to add to the change
 261          * @param string|array|null $tagsToRemove Tags to remove from the change
 262          * @param int|null &$rc_id The rc_id of the change to add the tags to.
 263          * Pass a variable whose value is null if the rc_id is not relevant or unknown.
 264          * @param int|null &$rev_id The rev_id of the change to add the tags to.
 265          * Pass a variable whose value is null if the rev_id is not relevant or unknown.
 266          * @param int|null &$log_id The log_id of the change to add the tags to.
 267          * Pass a variable whose value is null if the log_id is not relevant or unknown.
 268          * @param string|null $params Params to put in the ct_params field of table
 269          * 'change_tag' when adding tags
 270          * @param RecentChange|null $rc Recent change being tagged, in case the tagging accompanies
 271          * the action
 272          * @param User|null $user Tagging user, in case the tagging is subsequent to the tagged action
 273          *
 274          * @throws MWException When $rc_id, $rev_id and $log_id are all null
 275          * @return array Index 0 is an array of tags actually added, index 1 is an
 276          * array of tags actually removed, index 2 is an array of tags present on the
 277          * revision or log entry before any changes were made
 278          *
 279          * @since 1.25
 280          */
 281         public static function updateTags( $tagsToAdd, $tagsToRemove, &$rc_id = null,
 282                 &$rev_id = null, &$log_id = null, $params = null, RecentChange $rc = null,
 283                 User $user = null
 284         ) {
 285                 $tagsToAdd = array_filter( (array)$tagsToAdd ); // Make sure we're submitting all tags...
 286                 $tagsToRemove = array_filter( (array)$tagsToRemove );
 287
 288                 if ( !$rc_id && !$rev_id && !$log_id ) {
 289                         throw new MWException( 'At least one of: RCID, revision ID, and log ID MUST be ' .
 290                                 'specified when adding or removing a tag from a change!' );
 291                 }
 292
 293                 $dbw = wfGetDB( DB_MASTER );
 294
 295                 // Might as well look for rcids and so on.
 296                 if ( !$rc_id ) {
 297                         // Info might be out of date, somewhat fractionally, on replica DB.
 298                         // LogEntry/LogPage and WikiPage match rev/log/rc timestamps,
 299                         // so use that relation to avoid full table scans.
 300                         if ( $log_id ) {
 301                                 $rc_id = $dbw->selectField(
 302                                         [ 'logging', 'recentchanges' ],
 303                                         'rc_id',
 304                                         [
 305                                                 'log_id' => $log_id,
 306                                                 'rc_timestamp = log_timestamp',
 307                                                 'rc_logid = log_id'
 308                                         ],
 309                                         __METHOD__
 310                                 );
 311                         } elseif ( $rev_id ) {
 312                                 $rc_id = $dbw->selectField(
 313                                         [ 'revision', 'recentchanges' ],
 314                                         'rc_id',
 315                                         [
 316                                                 'rev_id' => $rev_id,
 317                                                 'rc_timestamp = rev_timestamp',
 318                                                 'rc_this_oldid = rev_id'
 319                                         ],
 320                                         __METHOD__
 321                                 );
 322                         }
 323                 } elseif ( !$log_id && !$rev_id ) {
 324                         // Info might be out of date, somewhat fractionally, on replica DB.
 325                         $log_id = $dbw->selectField(
 326                                 'recentchanges',
 327                                 'rc_logid',
 328                                 [ 'rc_id' => $rc_id ],
 329                                 __METHOD__
 330                         );
 331                         $rev_id = $dbw->selectField(
 332                                 'recentchanges',
 333                                 'rc_this_oldid',
 334                                 [ 'rc_id' => $rc_id ],
 335                                 __METHOD__
 336                         );
 337                 }
 338
 339                 if ( $log_id && !$rev_id ) {
 340                         $rev_id = $dbw->selectField(
 341                                 'log_search',
 342                                 'ls_value',
 343                                 [ 'ls_field' => 'associated_rev_id', 'ls_log_id' => $log_id ],
 344                                 __METHOD__
 345                         );
 346                 } elseif ( !$log_id && $rev_id ) {
 347                         $log_id = $dbw->selectField(
 348                                 'log_search',
 349                                 'ls_log_id',
 350                                 [ 'ls_field' => 'associated_rev_id', 'ls_value' => $rev_id ],
 351                                 __METHOD__
 352                         );
 353                 }
 354
 355                 $prevTags = self::getPrevTags( $rc_id, $log_id, $rev_id );
 356
 357                 // add tags
 358                 $tagsToAdd = array_values( array_diff( $tagsToAdd, $prevTags ) );
 359                 $newTags = array_unique( array_merge( $prevTags, $tagsToAdd ) );
 360
 361                 // remove tags
 362                 $tagsToRemove = array_values( array_intersect( $tagsToRemove, $newTags ) );
 363                 $newTags = array_values( array_diff( $newTags, $tagsToRemove ) );
 364
 365                 sort( $prevTags );
 366                 sort( $newTags );
 367                 if ( $prevTags == $newTags ) {
 368                         return [ [], [], $prevTags ];
 369                 }
 370
 371                 // insert a row into change_tag for each new tag
 372                 $changeTagDefStore = MediaWikiServices::getInstance()->getChangeTagDefStore();
 373                 if ( count( $tagsToAdd ) ) {
 374                         $changeTagMapping = [];
 375                         foreach ( $tagsToAdd as $tag ) {
 376                                 $changeTagMapping[$tag] = $changeTagDefStore->acquireId( $tag );
 377                         }
 378                         $fname = __METHOD__;
 379                         // T207881: update the counts at the end of the transaction
 380                         $dbw->onTransactionPreCommitOrIdle( function () use ( $dbw, $tagsToAdd, $fname ) {
 381                                 $dbw->update(
 382                                         'change_tag_def',
 383                                         [ 'ctd_count = ctd_count + 1' ],
 384                                         [ 'ctd_name' => $tagsToAdd ],
 385                                         $fname
 386                                 );
 387                         } );
 388
 389                         $tagsRows = [];
 390                         foreach ( $tagsToAdd as $tag ) {
 391                                 // Filter so we don't insert NULLs as zero accidentally.
 392                                 // Keep in mind that $rc_id === null means "I don't care/know about the
 393                                 // rc_id, just delete $tag on this revision/log entry". It doesn't
 394                                 // mean "only delete tags on this revision/log WHERE rc_id IS NULL".
 395                                 $tagsRows[] = array_filter(
 396                                         [
 397                                                 'ct_rc_id' => $rc_id,
 398                                                 'ct_log_id' => $log_id,
 399                                                 'ct_rev_id' => $rev_id,
 400                                                 'ct_params' => $params,
 401                                                 'ct_tag_id' => $changeTagMapping[$tag] ?? null,
 402                                         ]
 403                                 );
 404
 405                         }
 406
 407                         $dbw->insert( 'change_tag', $tagsRows, __METHOD__, [ 'IGNORE' ] );
 408                 }
 409
 410                 // delete from change_tag
 411                 if ( count( $tagsToRemove ) ) {
 412                         $fname = __METHOD__;
 413                         foreach ( $tagsToRemove as $tag ) {
 414                                 $conds = array_filter(
 415                                         [
 416                                                 'ct_rc_id' => $rc_id,
 417                                                 'ct_log_id' => $log_id,
 418                                                 'ct_rev_id' => $rev_id,
 419                                                 'ct_tag_id' => $changeTagDefStore->getId( $tag ),
 420                                         ]
 421                                 );
 422                                 $dbw->delete( 'change_tag', $conds, __METHOD__ );
 423                                 if ( $dbw->affectedRows() ) {
 424                                         // T207881: update the counts at the end of the transaction
 425                                         $dbw->onTransactionPreCommitOrIdle( function () use ( $dbw, $tag, $fname ) {
 426                                                 $dbw->update(
 427                                                         'change_tag_def',
 428                                                         [ 'ctd_count = ctd_count - 1' ],
 429                                                         [ 'ctd_name' => $tag ],
 430                                                         $fname
 431                                                 );
 432
 433                                                 $dbw->delete(
 434                                                         'change_tag_def',
 435                                                         [ 'ctd_name' => $tag, 'ctd_count' => 0, 'ctd_user_defined' => 0 ],
 436                                                         $fname
 437                                                 );
 438                                         } );
 439                                 }
 440                         }
 441                 }
 442
 443                 Hooks::run( 'ChangeTagsAfterUpdateTags', [ $tagsToAdd, $tagsToRemove, $prevTags,
 444                         $rc_id, $rev_id, $log_id, $params, $rc, $user ] );
 445
 446                 return [ $tagsToAdd, $tagsToRemove, $prevTags ];
 447         }
 448
 449         private static function getPrevTags( $rc_id = null, $log_id = null, $rev_id = null ) {
 450                 $conds = array_filter(
 451                         [
 452                                 'ct_rc_id' => $rc_id,
 453                                 'ct_log_id' => $log_id,
 454                                 'ct_rev_id' => $rev_id,
 455                         ]
 456                 );
 457
 458                 $dbw = wfGetDB( DB_MASTER );
 459                 $tagIds = $dbw->selectFieldValues( 'change_tag', 'ct_tag_id', $conds, __METHOD__ );
 460
 461                 $tags = [];
 462                 foreach ( $tagIds as $tagId ) {
 463                         $tags[] = MediaWikiServices::getInstance()->getChangeTagDefStore()->getName( (int)$tagId );
 464                 }
 465
 466                 return $tags;
 467         }
 468
 469         /**
 470          * Helper function to generate a fatal status with a 'not-allowed' type error.
 471          *
 472          * @param string $msgOne Message key to use in the case of one tag
 473          * @param string $msgMulti Message key to use in the case of more than one tag
 474          * @param array $tags Restricted tags (passed as $1 into the message, count of
 475          * $tags passed as $2)
 476          * @return Status
 477          * @since 1.25
 478          */
 479         protected static function restrictedTagError( $msgOne, $msgMulti, $tags ) {
 480                 $lang = RequestContext::getMain()->getLanguage();
 481                 $count = count( $tags );
 482                 return Status::newFatal( ( $count > 1 ) ? $msgMulti : $msgOne,
 483                         $lang->commaList( $tags ), $count );
 484         }
 485
 486         /**
 487          * Is it OK to allow the user to apply all the specified tags at the same time
 488          * as they edit/make the change?
 489          *
 490          * Extensions should not use this function, unless directly handling a user
 491          * request to add a tag to a revision or log entry that the user is making.
 492          *
 493          * @param array $tags Tags that you are interested in applying
 494          * @param User|null $user User whose permission you wish to check, or null to
 495          * check for a generic non-blocked user with the relevant rights
 496          * @return Status
 497          * @since 1.25
 498          */
 499         public static function canAddTagsAccompanyingChange( array $tags, User $user = null ) {
 500                 if ( !is_null( $user ) ) {
 501                         if ( !$user->isAllowed( 'applychangetags' ) ) {
 502                                 return Status::newFatal( 'tags-apply-no-permission' );
 503                         } elseif ( $user->getBlock() ) {
 504                                 // @TODO Ensure that the block does not apply to the `applychangetags`
 505                                 //       right.
 506                                 return Status::newFatal( 'tags-apply-blocked', $user->getName() );
 507                         }
 508                 }
 509
 510                 // to be applied, a tag has to be explicitly defined
 511                 $allowedTags = self::listExplicitlyDefinedTags();
 512                 Hooks::run( 'ChangeTagsAllowedAdd', [ &$allowedTags, $tags, $user ] );
 513                 $disallowedTags = array_diff( $tags, $allowedTags );
 514                 if ( $disallowedTags ) {
 515                         return self::restrictedTagError( 'tags-apply-not-allowed-one',
 516                                 'tags-apply-not-allowed-multi', $disallowedTags );
 517                 }
 518
 519                 return Status::newGood();
 520         }
 521
 522         /**
 523          * Adds tags to a given change, checking whether it is allowed first, but
 524          * without adding a log entry. Useful for cases where the tag is being added
 525          * along with the action that generated the change (e.g. tagging an edit as
 526          * it is being made).
 527          *
 528          * Extensions should not use this function, unless directly handling a user
 529          * request to add a particular tag. Normally, extensions should call
 530          * ChangeTags::updateTags() instead.
 531          *
 532          * @param array $tags Tags to apply
 533          * @param int|null $rc_id The rc_id of the change to add the tags to
 534          * @param int|null $rev_id The rev_id of the change to add the tags to
 535          * @param int|null $log_id The log_id of the change to add the tags to
 536          * @param string $params Params to put in the ct_params field of table
 537          * 'change_tag' when adding tags
 538          * @param User $user Who to give credit for the action
 539          * @return Status
 540          * @since 1.25
 541          */
 542         public static function addTagsAccompanyingChangeWithChecks(
 543                 array $tags, $rc_id, $rev_id, $log_id, $params, User $user
 544         ) {
 545                 // are we allowed to do this?
 546                 $result = self::canAddTagsAccompanyingChange( $tags, $user );
 547                 if ( !$result->isOK() ) {
 548                         $result->value = null;
 549                         return $result;
 550                 }
 551
 552                 // do it!
 553                 self::addTags( $tags, $rc_id, $rev_id, $log_id, $params );
 554
 555                 return Status::newGood( true );
 556         }
 557
 558         /**
 559          * Is it OK to allow the user to adds and remove the given tags tags to/from a
 560          * change?
 561          *
 562          * Extensions should not use this function, unless directly handling a user
 563          * request to add or remove tags from an existing revision or log entry.
 564          *
 565          * @param array $tagsToAdd Tags that you are interested in adding
 566          * @param array $tagsToRemove Tags that you are interested in removing
 567          * @param User|null $user User whose permission you wish to check, or null to
 568          * check for a generic non-blocked user with the relevant rights
 569          * @return Status
 570          * @since 1.25
 571          */
 572         public static function canUpdateTags( array $tagsToAdd, array $tagsToRemove,
 573                 User $user = null
 574         ) {
 575                 if ( !is_null( $user ) ) {
 576                         if ( !$user->isAllowed( 'changetags' ) ) {
 577                                 return Status::newFatal( 'tags-update-no-permission' );
 578                         } elseif ( $user->getBlock() ) {
 579                                 // @TODO Ensure that the block does not apply to the `changetags`
 580                                 //       right.
 581                                 return Status::newFatal( 'tags-update-blocked', $user->getName() );
 582                         }
 583                 }
 584
 585                 if ( $tagsToAdd ) {
 586                         // to be added, a tag has to be explicitly defined
 587                         // @todo Allow extensions to define tags that can be applied by users...
 588                         $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
 589                         $diff = array_diff( $tagsToAdd, $explicitlyDefinedTags );
 590                         if ( $diff ) {
 591                                 return self::restrictedTagError( 'tags-update-add-not-allowed-one',
 592                                         'tags-update-add-not-allowed-multi', $diff );
 593                         }
 594                 }
 595
 596                 if ( $tagsToRemove ) {
 597                         // to be removed, a tag must not be defined by an extension, or equivalently it
 598                         // has to be either explicitly defined or not defined at all
 599                         // (assuming no edge case of a tag both explicitly-defined and extension-defined)
 600                         $softwareDefinedTags = self::listSoftwareDefinedTags();
 601                         $intersect = array_intersect( $tagsToRemove, $softwareDefinedTags );
 602                         if ( $intersect ) {
 603                                 return self::restrictedTagError( 'tags-update-remove-not-allowed-one',
 604                                         'tags-update-remove-not-allowed-multi', $intersect );
 605                         }
 606                 }
 607
 608                 return Status::newGood();
 609         }
 610
 611         /**
 612          * Adds and/or removes tags to/from a given change, checking whether it is
 613          * allowed first, and adding a log entry afterwards.
 614          *
 615          * Includes a call to ChangeTags::canUpdateTags(), so your code doesn't need
 616          * to do that. However, it doesn't check whether the *_id parameters are a
 617          * valid combination. That is up to you to enforce. See ApiTag::execute() for
 618          * an example.
 619          *
 620          * Extensions should generally avoid this function. Call
 621          * ChangeTags::updateTags() instead, unless directly handling a user request
 622          * to add or remove tags from an existing revision or log entry.
 623          *
 624          * @param array|null $tagsToAdd If none, pass [] or null
 625          * @param array|null $tagsToRemove If none, pass [] or null
 626          * @param int|null $rc_id The rc_id of the change to add the tags to
 627          * @param int|null $rev_id The rev_id of the change to add the tags to
 628          * @param int|null $log_id The log_id of the change to add the tags to
 629          * @param string|null $params Params to put in the ct_params field of table
 630          * 'change_tag' when adding tags
 631          * @param string $reason Comment for the log
 632          * @param User $user Who to give credit for the action
 633          * @return Status If successful, the value of this Status object will be an
 634          * object (stdClass) with the following fields:
 635          *  - logId: the ID of the added log entry, or null if no log entry was added
 636          *    (i.e. no operation was performed)
 637          *  - addedTags: an array containing the tags that were actually added
 638          *  - removedTags: an array containing the tags that were actually removed
 639          * @since 1.25
 640          */
 641         public static function updateTagsWithChecks( $tagsToAdd, $tagsToRemove,
 642                 $rc_id, $rev_id, $log_id, $params, $reason, User $user
 643         ) {
 644                 if ( is_null( $tagsToAdd ) ) {
 645                         $tagsToAdd = [];
 646                 }
 647                 if ( is_null( $tagsToRemove ) ) {
 648                         $tagsToRemove = [];
 649                 }
 650                 if ( !$tagsToAdd && !$tagsToRemove ) {
 651                         // no-op, don't bother
 652                         return Status::newGood( (object)[
 653                                 'logId' => null,
 654                                 'addedTags' => [],
 655                                 'removedTags' => [],
 656                         ] );
 657                 }
 658
 659                 // are we allowed to do this?
 660                 $result = self::canUpdateTags( $tagsToAdd, $tagsToRemove, $user );
 661                 if ( !$result->isOK() ) {
 662                         $result->value = null;
 663                         return $result;
 664                 }
 665
 666                 // basic rate limiting
 667                 if ( $user->pingLimiter( 'changetag' ) ) {
 668                         return Status::newFatal( 'actionthrottledtext' );
 669                 }
 670
 671                 // do it!
 672                 list( $tagsAdded, $tagsRemoved, $initialTags ) = self::updateTags( $tagsToAdd,
 673                         $tagsToRemove, $rc_id, $rev_id, $log_id, $params, null, $user );
 674                 if ( !$tagsAdded && !$tagsRemoved ) {
 675                         // no-op, don't log it
 676                         return Status::newGood( (object)[
 677                                 'logId' => null,
 678                                 'addedTags' => [],
 679                                 'removedTags' => [],
 680                         ] );
 681                 }
 682
 683                 // log it
 684                 $logEntry = new ManualLogEntry( 'tag', 'update' );
 685                 $logEntry->setPerformer( $user );
 686                 $logEntry->setComment( $reason );
 687
 688                 // find the appropriate target page
 689                 if ( $rev_id ) {
 690                         $rev = Revision::newFromId( $rev_id );
 691                         if ( $rev ) {
 692                                 $logEntry->setTarget( $rev->getTitle() );
 693                         }
 694                 } elseif ( $log_id ) {
 695                         // This function is from revision deletion logic and has nothing to do with
 696                         // change tags, but it appears to be the only other place in core where we
 697                         // perform logged actions on log items.
 698                         $logEntry->setTarget( RevDelLogList::suggestTarget( null, [ $log_id ] ) );
 699                 }
 700
 701                 if ( !$logEntry->getTarget() ) {
 702                         // target is required, so we have to set something
 703                         $logEntry->setTarget( SpecialPage::getTitleFor( 'Tags' ) );
 704                 }
 705
 706                 $logParams = [
 707                         '4::revid' => $rev_id,
 708                         '5::logid' => $log_id,
 709                         '6:list:tagsAdded' => $tagsAdded,
 710                         '7:number:tagsAddedCount' => count( $tagsAdded ),
 711                         '8:list:tagsRemoved' => $tagsRemoved,
 712                         '9:number:tagsRemovedCount' => count( $tagsRemoved ),
 713                         'initialTags' => $initialTags,
 714                 ];
 715                 $logEntry->setParameters( $logParams );
 716                 $logEntry->setRelations( [ 'Tag' => array_merge( $tagsAdded, $tagsRemoved ) ] );
 717
 718                 $dbw = wfGetDB( DB_MASTER );
 719                 $logId = $logEntry->insert( $dbw );
 720                 // Only send this to UDP, not RC, similar to patrol events
 721                 $logEntry->publish( $logId, 'udp' );
 722
 723                 return Status::newGood( (object)[
 724                         'logId' => $logId,
 725                         'addedTags' => $tagsAdded,
 726                         'removedTags' => $tagsRemoved,
 727                 ] );
 728         }
 729
 730         /**
 731          * Applies all tags-related changes to a query.
 732          * Handles selecting tags, and filtering.
 733          * Needs $tables to be set up properly, so we can figure out which join conditions to use.
 734          *
 735          * WARNING: If $filter_tag contains more than one tag, this function will add DISTINCT,
 736          * which may cause performance problems for your query unless you put the ID field of your
 737          * table at the end of the ORDER BY, and set a GROUP BY equal to the ORDER BY. For example,
 738          * if you had ORDER BY foo_timestamp DESC, you will now need GROUP BY foo_timestamp, foo_id
 739          * ORDER BY foo_timestamp DESC, foo_id DESC.
 740          *
 741          * @param string|array &$tables Table names, see Database::select
 742          * @param string|array &$fields Fields used in query, see Database::select
 743          * @param string|array &$conds Conditions used in query, see Database::select
 744          * @param array &$join_conds Join conditions, see Database::select
 745          * @param string|array &$options Options, see Database::select
 746          * @param string|array $filter_tag Tag(s) to select on
 747          *
 748          * @throws MWException When unable to determine appropriate JOIN condition for tagging
 749          */
 750         public static function modifyDisplayQuery( &$tables, &$fields, &$conds,
 751                 &$join_conds, &$options, $filter_tag = ''
 752         ) {
 753                 global $wgUseTagFilter;
 754
 755                 // Normalize to arrays
 756                 $tables = (array)$tables;
 757                 $fields = (array)$fields;
 758                 $conds = (array)$conds;
 759                 $options = (array)$options;
 760
 761                 $fields['ts_tags'] = self::makeTagSummarySubquery( $tables );
 762
 763                 // Figure out which ID field to use
 764                 if ( in_array( 'recentchanges', $tables ) ) {
 765                         $join_cond = 'ct_rc_id=rc_id';
 766                 } elseif ( in_array( 'logging', $tables ) ) {
 767                         $join_cond = 'ct_log_id=log_id';
 768                 } elseif ( in_array( 'revision', $tables ) ) {
 769                         $join_cond = 'ct_rev_id=rev_id';
 770                 } elseif ( in_array( 'archive', $tables ) ) {
 771                         $join_cond = 'ct_rev_id=ar_rev_id';
 772                 } else {
 773                         throw new MWException( 'Unable to determine appropriate JOIN condition for tagging.' );
 774                 }
 775
 776                 if ( $wgUseTagFilter && $filter_tag ) {
 777                         // Somebody wants to filter on a tag.
 778                         // Add an INNER JOIN on change_tag
 779
 780                         $tables[] = 'change_tag';
 781                         $join_conds['change_tag'] = [ 'JOIN', $join_cond ];
 782                         $filterTagIds = [];
 783                         $changeTagDefStore = MediaWikiServices::getInstance()->getChangeTagDefStore();
 784                         foreach ( (array)$filter_tag as $filterTagName ) {
 785                                 try {
 786                                         $filterTagIds[] = $changeTagDefStore->getId( $filterTagName );
 787                                 } catch ( NameTableAccessException $exception ) {
 788                                         // Return nothing.
 789                                         $conds[] = '0';
 790                                         break;
 791                                 }
 792                         }
 793
 794                         if ( $filterTagIds !== [] ) {
 795                                 $conds['ct_tag_id'] = $filterTagIds;
 796                         }
 797
 798                         if (
 799                                 is_array( $filter_tag ) && count( $filter_tag ) > 1 &&
 800                                 !in_array( 'DISTINCT', $options )
 801                         ) {
 802                                 $options[] = 'DISTINCT';
 803                         }
 804                 }
 805         }
 806
 807         /**
 808          * Make the tag summary subquery based on the given tables and return it.
 809          *
 810          * @param string|array $tables Table names, see Database::select
 811          *
 812          * @return string tag summary subqeury
 813          * @throws MWException When unable to determine appropriate JOIN condition for tagging
 814          */
 815         public static function makeTagSummarySubquery( $tables ) {
 816                 // Normalize to arrays
 817                 $tables = (array)$tables;
 818
 819                 // Figure out which ID field to use
 820                 if ( in_array( 'recentchanges', $tables ) ) {
 821                         $join_cond = 'ct_rc_id=rc_id';
 822                 } elseif ( in_array( 'logging', $tables ) ) {
 823                         $join_cond = 'ct_log_id=log_id';
 824                 } elseif ( in_array( 'revision', $tables ) ) {
 825                         $join_cond = 'ct_rev_id=rev_id';
 826                 } elseif ( in_array( 'archive', $tables ) ) {
 827                         $join_cond = 'ct_rev_id=ar_rev_id';
 828                 } else {
 829                         throw new MWException( 'Unable to determine appropriate JOIN condition for tagging.' );
 830                 }
 831
 832                 $tagTables = [ 'change_tag', 'change_tag_def' ];
 833                 $join_cond_ts_tags = [ 'change_tag_def' => [ 'JOIN', 'ct_tag_id=ctd_id' ] ];
 834                 $field = 'ctd_name';
 835
 836                 return wfGetDB( DB_REPLICA )->buildGroupConcatField(
 837                         ',', $tagTables, $field, $join_cond, $join_cond_ts_tags
 838                 );
 839         }
 840
 841         /**
 842          * Build a text box to select a change tag
 843          *
 844          * @param string $selected Tag to select by default
 845          * @param bool $ooui Use an OOUI TextInputWidget as selector instead of a non-OOUI input field
 846          *        You need to call OutputPage::enableOOUI() yourself.
 847          * @param IContextSource|null $context
 848          * @note Even though it takes null as a valid argument, an IContextSource is preferred
 849          *       in a new code, as the null value can change in the future
 850          * @return array an array of (label, selector)
 851          */
 852         public static function buildTagFilterSelector(
 853                 $selected = '', $ooui = false, IContextSource $context = null
 854         ) {
 855                 if ( !$context ) {
 856                         $context = RequestContext::getMain();
 857                 }
 858
 859                 $config = $context->getConfig();
 860                 if ( !$config->get( 'UseTagFilter' ) || !count( self::listDefinedTags() ) ) {
 861                         return [];
 862                 }
 863
 864                 $data = [
 865                         Html::rawElement(
 866                                 'label',
 867                                 [ 'for' => 'tagfilter' ],
 868                                 $context->msg( 'tag-filter' )->parse()
 869                         )
 870                 ];
 871
 872                 if ( $ooui ) {
 873                         $data[] = new OOUI\TextInputWidget( [
 874                                 'id' => 'tagfilter',
 875                                 'name' => 'tagfilter',
 876                                 'value' => $selected,
 877                                 'classes' => 'mw-tagfilter-input',
 878                         ] );
 879                 } else {
 880                         $data[] = Xml::input(
 881                                 'tagfilter',
 882                                 20,
 883                                 $selected,
 884                                 [ 'class' => 'mw-tagfilter-input mw-ui-input mw-ui-input-inline', 'id' => 'tagfilter' ]
 885                         );
 886                 }
 887
 888                 return $data;
 889         }
 890
 891         /**
 892          * Set ctd_user_defined = 1 in change_tag_def without checking that the tag name is valid.
 893          * Extensions should NOT use this function; they can use the ListDefinedTags
 894          * hook instead.
 895          *
 896          * @param string $tag Tag to create
 897          * @since 1.25
 898          */
 899         public static function defineTag( $tag ) {
 900                 $dbw = wfGetDB( DB_MASTER );
 901                 $tagDef = [
 902                         'ctd_name' => $tag,
 903                         'ctd_user_defined' => 1,
 904                         'ctd_count' => 0
 905                 ];
 906                 $dbw->upsert(
 907                         'change_tag_def',
 908                         $tagDef,
 909                         [ 'ctd_name' ],
 910                         [ 'ctd_user_defined' => 1 ],
 911                         __METHOD__
 912                 );
 913
 914                 // clear the memcache of defined tags
 915                 self::purgeTagCacheAll();
 916         }
 917
 918         /**
 919          * Update ctd_user_defined = 0 field in change_tag_def.
 920          * The tag may remain in use by extensions, and may still show up as 'defined'
 921          * if an extension is setting it from the ListDefinedTags hook.
 922          *
 923          * @param string $tag Tag to remove
 924          * @since 1.25
 925          */
 926         public static function undefineTag( $tag ) {
 927                 $dbw = wfGetDB( DB_MASTER );
 928
 929                 $dbw->update(
 930                         'change_tag_def',
 931                         [ 'ctd_user_defined' => 0 ],
 932                         [ 'ctd_name' => $tag ],
 933                         __METHOD__
 934                 );
 935
 936                 $dbw->delete(
 937                         'change_tag_def',
 938                         [ 'ctd_name' => $tag, 'ctd_count' => 0 ],
 939                         __METHOD__
 940                 );
 941
 942                 // clear the memcache of defined tags
 943                 self::purgeTagCacheAll();
 944         }
 945
 946         /**
 947          * Writes a tag action into the tag management log.
 948          *
 949          * @param string $action
 950          * @param string $tag
 951          * @param string $reason
 952          * @param User $user Who to attribute the action to
 953          * @param int|null $tagCount For deletion only, how many usages the tag had before
 954          * it was deleted.
 955          * @param array $logEntryTags Change tags to apply to the entry
 956          * that will be created in the tag management log
 957          * @return int ID of the inserted log entry
 958          * @since 1.25
 959          */
 960         protected static function logTagManagementAction( $action, $tag, $reason,
 961                 User $user, $tagCount = null, array $logEntryTags = []
 962         ) {
 963                 $dbw = wfGetDB( DB_MASTER );
 964
 965                 $logEntry = new ManualLogEntry( 'managetags', $action );
 966                 $logEntry->setPerformer( $user );
 967                 // target page is not relevant, but it has to be set, so we just put in
 968                 // the title of Special:Tags
 969                 $logEntry->setTarget( Title::newFromText( 'Special:Tags' ) );
 970                 $logEntry->setComment( $reason );
 971
 972                 $params = [ '4::tag' => $tag ];
 973                 if ( !is_null( $tagCount ) ) {
 974                         $params['5:number:count'] = $tagCount;
 975                 }
 976                 $logEntry->setParameters( $params );
 977                 $logEntry->setRelations( [ 'Tag' => $tag ] );
 978                 $logEntry->setTags( $logEntryTags );
 979
 980                 $logId = $logEntry->insert( $dbw );
 981                 $logEntry->publish( $logId );
 982                 return $logId;
 983         }
 984
 985         /**
 986          * Is it OK to allow the user to activate this tag?
 987          *
 988          * @param string $tag Tag that you are interested in activating
 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 canActivateTag( $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->getBlock() ) {
 999                                 // @TODO Ensure that the block does not apply to the `managechangetags`
1000                                 //       right.
1001                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1002                         }
1003                 }
1004
1005                 // defined tags cannot be activated (a defined tag is either extension-
1006                 // defined, in which case the extension chooses whether or not to active it;
1007                 // or user-defined, in which case it is considered active)
1008                 $definedTags = self::listDefinedTags();
1009                 if ( in_array( $tag, $definedTags ) ) {
1010                         return Status::newFatal( 'tags-activate-not-allowed', $tag );
1011                 }
1012
1013                 // non-existing tags cannot be activated
1014                 $tagUsage = self::tagUsageStatistics();
1015                 if ( !isset( $tagUsage[$tag] ) ) { // we already know the tag is undefined
1016                         return Status::newFatal( 'tags-activate-not-found', $tag );
1017                 }
1018
1019                 return Status::newGood();
1020         }
1021
1022         /**
1023          * Activates a tag, checking whether it is allowed first, and adding a log
1024          * entry afterwards.
1025          *
1026          * Includes a call to ChangeTag::canActivateTag(), so your code doesn't need
1027          * to do that.
1028          *
1029          * @param string $tag
1030          * @param string $reason
1031          * @param User $user Who to give credit for the action
1032          * @param bool $ignoreWarnings Can be used for API interaction, default false
1033          * @param array $logEntryTags Change tags to apply to the entry
1034          * that will be created in the tag management log
1035          * @return Status If successful, the Status contains the ID of the added log
1036          * entry as its value
1037          * @since 1.25
1038          */
1039         public static function activateTagWithChecks( $tag, $reason, User $user,
1040                 $ignoreWarnings = false, array $logEntryTags = []
1041         ) {
1042                 // are we allowed to do this?
1043                 $result = self::canActivateTag( $tag, $user );
1044                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1045                         $result->value = null;
1046                         return $result;
1047                 }
1048
1049                 // do it!
1050                 self::defineTag( $tag );
1051
1052                 // log it
1053                 $logId = self::logTagManagementAction( 'activate', $tag, $reason, $user,
1054                         null, $logEntryTags );
1055
1056                 return Status::newGood( $logId );
1057         }
1058
1059         /**
1060          * Is it OK to allow the user to deactivate this tag?
1061          *
1062          * @param string $tag Tag that you are interested in deactivating
1063          * @param User|null $user User whose permission you wish to check, or null if
1064          * you don't care (e.g. maintenance scripts)
1065          * @return Status
1066          * @since 1.25
1067          */
1068         public static function canDeactivateTag( $tag, User $user = null ) {
1069                 if ( !is_null( $user ) ) {
1070                         if ( !$user->isAllowed( 'managechangetags' ) ) {
1071                                 return Status::newFatal( 'tags-manage-no-permission' );
1072                         } elseif ( $user->getBlock() ) {
1073                                 // @TODO Ensure that the block does not apply to the `managechangetags`
1074                                 //       right.
1075                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1076                         }
1077                 }
1078
1079                 // only explicitly-defined tags can be deactivated
1080                 $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
1081                 if ( !in_array( $tag, $explicitlyDefinedTags ) ) {
1082                         return Status::newFatal( 'tags-deactivate-not-allowed', $tag );
1083                 }
1084                 return Status::newGood();
1085         }
1086
1087         /**
1088          * Deactivates a tag, checking whether it is allowed first, and adding a log
1089          * entry afterwards.
1090          *
1091          * Includes a call to ChangeTag::canDeactivateTag(), so your code doesn't need
1092          * to do that.
1093          *
1094          * @param string $tag
1095          * @param string $reason
1096          * @param User $user Who to give credit for the action
1097          * @param bool $ignoreWarnings Can be used for API interaction, default false
1098          * @param array $logEntryTags Change tags to apply to the entry
1099          * that will be created in the tag management log
1100          * @return Status If successful, the Status contains the ID of the added log
1101          * entry as its value
1102          * @since 1.25
1103          */
1104         public static function deactivateTagWithChecks( $tag, $reason, User $user,
1105                 $ignoreWarnings = false, array $logEntryTags = []
1106         ) {
1107                 // are we allowed to do this?
1108                 $result = self::canDeactivateTag( $tag, $user );
1109                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1110                         $result->value = null;
1111                         return $result;
1112                 }
1113
1114                 // do it!
1115                 self::undefineTag( $tag );
1116
1117                 // log it
1118                 $logId = self::logTagManagementAction( 'deactivate', $tag, $reason, $user,
1119                         null, $logEntryTags );
1120
1121                 return Status::newGood( $logId );
1122         }
1123
1124         /**
1125          * Is the tag name valid?
1126          *
1127          * @param string $tag Tag that you are interested in creating
1128          * @return Status
1129          * @since 1.30
1130          */
1131         public static function isTagNameValid( $tag ) {
1132                 // no empty tags
1133                 if ( $tag === '' ) {
1134                         return Status::newFatal( 'tags-create-no-name' );
1135                 }
1136
1137                 // tags cannot contain commas (used to be used as a delimiter in tag_summary table),
1138                 // pipe (used as a delimiter between multiple tags in
1139                 // SpecialRecentchanges and friends), or slashes (would break tag description messages in
1140                 // MediaWiki namespace)
1141                 if ( strpos( $tag, ',' ) !== false || strpos( $tag, '|' ) !== false
1142                         || strpos( $tag, '/' ) !== false ) {
1143                         return Status::newFatal( 'tags-create-invalid-chars' );
1144                 }
1145
1146                 // could the MediaWiki namespace description messages be created?
1147                 $title = Title::makeTitleSafe( NS_MEDIAWIKI, "Tag-$tag-description" );
1148                 if ( is_null( $title ) ) {
1149                         return Status::newFatal( 'tags-create-invalid-title-chars' );
1150                 }
1151
1152                 return Status::newGood();
1153         }
1154
1155         /**
1156          * Is it OK to allow the user to create this tag?
1157          *
1158          * Extensions should NOT use this function. In most cases, a tag can be
1159          * defined using the ListDefinedTags hook without any checking.
1160          *
1161          * @param string $tag Tag that you are interested in creating
1162          * @param User|null $user User whose permission you wish to check, or null if
1163          * you don't care (e.g. maintenance scripts)
1164          * @return Status
1165          * @since 1.25
1166          */
1167         public static function canCreateTag( $tag, User $user = null ) {
1168                 if ( !is_null( $user ) ) {
1169                         if ( !$user->isAllowed( 'managechangetags' ) ) {
1170                                 return Status::newFatal( 'tags-manage-no-permission' );
1171                         } elseif ( $user->getBlock() ) {
1172                                 // @TODO Ensure that the block does not apply to the `managechangetags`
1173                                 //       right.
1174                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1175                         }
1176                 }
1177
1178                 $status = self::isTagNameValid( $tag );
1179                 if ( !$status->isGood() ) {
1180                         return $status;
1181                 }
1182
1183                 // does the tag already exist?
1184                 $tagUsage = self::tagUsageStatistics();
1185                 if ( isset( $tagUsage[$tag] ) || in_array( $tag, self::listDefinedTags() ) ) {
1186                         return Status::newFatal( 'tags-create-already-exists', $tag );
1187                 }
1188
1189                 // check with hooks
1190                 $canCreateResult = Status::newGood();
1191                 Hooks::run( 'ChangeTagCanCreate', [ $tag, $user, &$canCreateResult ] );
1192                 return $canCreateResult;
1193         }
1194
1195         /**
1196          * Creates a tag by adding it to `change_tag_def` table.
1197          *
1198          * Extensions should NOT use this function; they can use the ListDefinedTags
1199          * hook instead.
1200          *
1201          * Includes a call to ChangeTag::canCreateTag(), so your code doesn't need to
1202          * do that.
1203          *
1204          * @param string $tag
1205          * @param string $reason
1206          * @param User $user Who to give credit for the action
1207          * @param bool $ignoreWarnings Can be used for API interaction, default false
1208          * @param array $logEntryTags Change tags to apply to the entry
1209          * that will be created in the tag management log
1210          * @return Status If successful, the Status contains the ID of the added log
1211          * entry as its value
1212          * @since 1.25
1213          */
1214         public static function createTagWithChecks( $tag, $reason, User $user,
1215                 $ignoreWarnings = false, array $logEntryTags = []
1216         ) {
1217                 // are we allowed to do this?
1218                 $result = self::canCreateTag( $tag, $user );
1219                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1220                         $result->value = null;
1221                         return $result;
1222                 }
1223
1224                 // do it!
1225                 self::defineTag( $tag );
1226
1227                 // log it
1228                 $logId = self::logTagManagementAction( 'create', $tag, $reason, $user,
1229                         null, $logEntryTags );
1230
1231                 return Status::newGood( $logId );
1232         }
1233
1234         /**
1235          * Permanently removes all traces of a tag from the DB. Good for removing
1236          * misspelt or temporary tags.
1237          *
1238          * This function should be directly called by maintenance scripts only, never
1239          * by user-facing code. See deleteTagWithChecks() for functionality that can
1240          * safely be exposed to users.
1241          *
1242          * @param string $tag Tag to remove
1243          * @return Status The returned status will be good unless a hook changed it
1244          * @since 1.25
1245          */
1246         public static function deleteTagEverywhere( $tag ) {
1247                 $dbw = wfGetDB( DB_MASTER );
1248                 $dbw->startAtomic( __METHOD__ );
1249
1250                 // fetch tag id, this must be done before calling undefineTag(), see T225564
1251                 $tagId = MediaWikiServices::getInstance()->getChangeTagDefStore()->getId( $tag );
1252
1253                 // set ctd_user_defined = 0
1254                 self::undefineTag( $tag );
1255
1256                 // delete from change_tag
1257                 $dbw->delete( 'change_tag', [ 'ct_tag_id' => $tagId ], __METHOD__ );
1258                 $dbw->delete( 'change_tag_def', [ 'ctd_name' => $tag ], __METHOD__ );
1259                 $dbw->endAtomic( __METHOD__ );
1260
1261                 // give extensions a chance
1262                 $status = Status::newGood();
1263                 Hooks::run( 'ChangeTagAfterDelete', [ $tag, &$status ] );
1264                 // let's not allow error results, as the actual tag deletion succeeded
1265                 if ( !$status->isOK() ) {
1266                         wfDebug( 'ChangeTagAfterDelete error condition downgraded to warning' );
1267                         $status->setOK( true );
1268                 }
1269
1270                 // clear the memcache of defined tags
1271                 self::purgeTagCacheAll();
1272
1273                 return $status;
1274         }
1275
1276         /**
1277          * Is it OK to allow the user to delete this tag?
1278          *
1279          * @param string $tag Tag that you are interested in deleting
1280          * @param User|null $user User whose permission you wish to check, or null if
1281          * you don't care (e.g. maintenance scripts)
1282          * @return Status
1283          * @since 1.25
1284          */
1285         public static function canDeleteTag( $tag, User $user = null ) {
1286                 $tagUsage = self::tagUsageStatistics();
1287
1288                 if ( !is_null( $user ) ) {
1289                         if ( !$user->isAllowed( 'deletechangetags' ) ) {
1290                                 return Status::newFatal( 'tags-delete-no-permission' );
1291                         } elseif ( $user->getBlock() ) {
1292                                 // @TODO Ensure that the block does not apply to the `deletechangetags`
1293                                 //       right.
1294                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1295                         }
1296                 }
1297
1298                 if ( !isset( $tagUsage[$tag] ) && !in_array( $tag, self::listDefinedTags() ) ) {
1299                         return Status::newFatal( 'tags-delete-not-found', $tag );
1300                 }
1301
1302                 if ( isset( $tagUsage[$tag] ) && $tagUsage[$tag] > self::MAX_DELETE_USES ) {
1303                         return Status::newFatal( 'tags-delete-too-many-uses', $tag, self::MAX_DELETE_USES );
1304                 }
1305
1306                 $softwareDefined = self::listSoftwareDefinedTags();
1307                 if ( in_array( $tag, $softwareDefined ) ) {
1308                         // extension-defined tags can't be deleted unless the extension
1309                         // specifically allows it
1310                         $status = Status::newFatal( 'tags-delete-not-allowed' );
1311                 } else {
1312                         // user-defined tags are deletable unless otherwise specified
1313                         $status = Status::newGood();
1314                 }
1315
1316                 Hooks::run( 'ChangeTagCanDelete', [ $tag, $user, &$status ] );
1317                 return $status;
1318         }
1319
1320         /**
1321          * Deletes a tag, checking whether it is allowed first, and adding a log entry
1322          * afterwards.
1323          *
1324          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
1325          * do that.
1326          *
1327          * @param string $tag
1328          * @param string $reason
1329          * @param User $user Who to give credit for the action
1330          * @param bool $ignoreWarnings Can be used for API interaction, default false
1331          * @param array $logEntryTags Change tags to apply to the entry
1332          * that will be created in the tag management log
1333          * @return Status If successful, the Status contains the ID of the added log
1334          * entry as its value
1335          * @since 1.25
1336          */
1337         public static function deleteTagWithChecks( $tag, $reason, User $user,
1338                 $ignoreWarnings = false, array $logEntryTags = []
1339         ) {
1340                 // are we allowed to do this?
1341                 $result = self::canDeleteTag( $tag, $user );
1342                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1343                         $result->value = null;
1344                         return $result;
1345                 }
1346
1347                 // store the tag usage statistics
1348                 $tagUsage = self::tagUsageStatistics();
1349                 $hitcount = $tagUsage[$tag] ?? 0;
1350
1351                 // do it!
1352                 $deleteResult = self::deleteTagEverywhere( $tag );
1353                 if ( !$deleteResult->isOK() ) {
1354                         return $deleteResult;
1355                 }
1356
1357                 // log it
1358                 $logId = self::logTagManagementAction( 'delete', $tag, $reason, $user,
1359                         $hitcount, $logEntryTags );
1360
1361                 $deleteResult->value = $logId;
1362                 return $deleteResult;
1363         }
1364
1365         /**
1366          * Lists those tags which core or extensions report as being "active".
1367          *
1368          * @return array
1369          * @since 1.25
1370          */
1371         public static function listSoftwareActivatedTags() {
1372                 // core active tags
1373                 $tags = self::getSoftwareTags();
1374                 if ( !Hooks::isRegistered( 'ChangeTagsListActive' ) ) {
1375                         return $tags;
1376                 }
1377                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1378                 return $cache->getWithSetCallback(
1379                         $cache->makeKey( 'active-tags' ),
1380                         WANObjectCache::TTL_MINUTE * 5,
1381                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1382                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1383
1384                                 // Ask extensions which tags they consider active
1385                                 Hooks::run( 'ChangeTagsListActive', [ &$tags ] );
1386                                 return $tags;
1387                         },
1388                         [
1389                                 'checkKeys' => [ $cache->makeKey( 'active-tags' ) ],
1390                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1391                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1392                         ]
1393                 );
1394         }
1395
1396         /**
1397          * Basically lists defined tags which count even if they aren't applied to anything.
1398          * It returns a union of the results of listExplicitlyDefinedTags()
1399          *
1400          * @return string[] Array of strings: tags
1401          */
1402         public static function listDefinedTags() {
1403                 $tags1 = self::listExplicitlyDefinedTags();
1404                 $tags2 = self::listSoftwareDefinedTags();
1405                 return array_values( array_unique( array_merge( $tags1, $tags2 ) ) );
1406         }
1407
1408         /**
1409          * Lists tags explicitly defined in the `change_tag_def` table of the database.
1410          *
1411          * Tries memcached first.
1412          *
1413          * @return string[] Array of strings: tags
1414          * @since 1.25
1415          */
1416         public static function listExplicitlyDefinedTags() {
1417                 $fname = __METHOD__;
1418
1419                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1420                 return $cache->getWithSetCallback(
1421                         $cache->makeKey( 'valid-tags-db' ),
1422                         WANObjectCache::TTL_MINUTE * 5,
1423                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1424                                 $dbr = wfGetDB( DB_REPLICA );
1425
1426                                 $setOpts += Database::getCacheSetOptions( $dbr );
1427
1428                                 $tags = $dbr->selectFieldValues(
1429                                         'change_tag_def',
1430                                         'ctd_name',
1431                                         [ 'ctd_user_defined' => 1 ],
1432                                         $fname
1433                                 );
1434
1435                                 return array_filter( array_unique( $tags ) );
1436                         },
1437                         [
1438                                 'checkKeys' => [ $cache->makeKey( 'valid-tags-db' ) ],
1439                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1440                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1441                         ]
1442                 );
1443         }
1444
1445         /**
1446          * Lists tags defined by core or extensions using the ListDefinedTags hook.
1447          * Extensions need only define those tags they deem to be in active use.
1448          *
1449          * Tries memcached first.
1450          *
1451          * @return string[] Array of strings: tags
1452          * @since 1.25
1453          */
1454         public static function listSoftwareDefinedTags() {
1455                 // core defined tags
1456                 $tags = self::getSoftwareTags( true );
1457                 if ( !Hooks::isRegistered( 'ListDefinedTags' ) ) {
1458                         return $tags;
1459                 }
1460                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1461                 return $cache->getWithSetCallback(
1462                         $cache->makeKey( 'valid-tags-hook' ),
1463                         WANObjectCache::TTL_MINUTE * 5,
1464                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1465                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1466
1467                                 Hooks::run( 'ListDefinedTags', [ &$tags ] );
1468                                 return array_filter( array_unique( $tags ) );
1469                         },
1470                         [
1471                                 'checkKeys' => [ $cache->makeKey( 'valid-tags-hook' ) ],
1472                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1473                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1474                         ]
1475                 );
1476         }
1477
1478         /**
1479          * Invalidates the short-term cache of defined tags used by the
1480          * list*DefinedTags functions, as well as the tag statistics cache.
1481          * @since 1.25
1482          */
1483         public static function purgeTagCacheAll() {
1484                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1485
1486                 $cache->touchCheckKey( $cache->makeKey( 'active-tags' ) );
1487                 $cache->touchCheckKey( $cache->makeKey( 'valid-tags-db' ) );
1488                 $cache->touchCheckKey( $cache->makeKey( 'valid-tags-hook' ) );
1489                 $cache->touchCheckKey( $cache->makeKey( 'tags-usage-statistics' ) );
1490
1491                 MediaWikiServices::getInstance()->getChangeTagDefStore()->reloadMap();
1492         }
1493
1494         /**
1495          * Returns a map of any tags used on the wiki to number of edits
1496          * tagged with them, ordered descending by the hitcount.
1497          * This does not include tags defined somewhere that have never been applied.
1498          * @return array Array of string => int
1499          */
1500         public static function tagUsageStatistics() {
1501                 $fname = __METHOD__;
1502
1503                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1504                 return $cache->getWithSetCallback(
1505                         $cache->makeKey( 'tags-usage-statistics' ),
1506                         WANObjectCache::TTL_MINUTE * 5,
1507                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1508                                 $dbr = wfGetDB( DB_REPLICA );
1509                                 $res = $dbr->select(
1510                                         'change_tag_def',
1511                                         [ 'ctd_name', 'ctd_count' ],
1512                                         [],
1513                                         $fname,
1514                                         [ 'ORDER BY' => 'ctd_count DESC' ]
1515                                 );
1516
1517                                 $out = [];
1518                                 foreach ( $res as $row ) {
1519                                         $out[$row->ctd_name] = $row->ctd_count;
1520                                 }
1521
1522                                 return $out;
1523                         },
1524                         [
1525                                 'checkKeys' => [ $cache->makeKey( 'tags-usage-statistics' ) ],
1526                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1527                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1528                         ]
1529                 );
1530         }
1531
1532         /**
1533          * Indicate whether change tag editing UI is relevant
1534          *
1535          * Returns true if the user has the necessary right and there are any
1536          * editable tags defined.
1537          *
1538          * This intentionally doesn't check "any addable || any deletable", because
1539          * it seems like it would be more confusing than useful if the checkboxes
1540          * suddenly showed up because some abuse filter stopped defining a tag and
1541          * then suddenly disappeared when someone deleted all uses of that tag.
1542          *
1543          * @param User $user
1544          * @return bool
1545          */
1546         public static function showTagEditingUI( User $user ) {
1547                 return $user->isAllowed( 'changetags' ) && (bool)self::listExplicitlyDefinedTags();
1548         }
1549 }