includes/changetags/ChangeTags.php

   1 <?php
   2 /**
   3  * Recent changes tagging.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Change tagging
  22  */
  23
  24 class ChangeTags {
  25         /**
  26          * Can't delete tags with more than this many uses. Similar in intent to
  27          * the bigdelete user right
  28          * @todo Use the job queue for tag deletion to avoid this restriction
  29          */
  30         const MAX_DELETE_USES = 5000;
  31
  32         /**
  33          * @var string[]
  34          */
  35         private static $coreTags = [ 'mw-contentmodelchange' ];
  36
  37         /**
  38          * Creates HTML for the given tags
  39          *
  40          * @param string $tags Comma-separated list of tags
  41          * @param string $page A label for the type of action which is being displayed,
  42          *   for example: 'history', 'contributions' or 'newpages'
  43          * @param IContextSource|null $context
  44          * @note Even though it takes null as a valid argument, an IContextSource is preferred
  45          *       in a new code, as the null value is subject to change in the future
  46          * @return array Array with two items: (html, classes)
  47          *   - html: String: HTML for displaying the tags (empty string when param $tags is empty)
  48          *   - classes: Array of strings: CSS classes used in the generated html, one class for each tag
  49          */
  50         public static function formatSummaryRow( $tags, $page, IContextSource $context = null ) {
  51                 if ( !$tags ) {
  52                         return [ '', [] ];
  53                 }
  54                 if ( !$context ) {
  55                         $context = RequestContext::getMain();
  56                 }
  57
  58                 $classes = [];
  59
  60                 $tags = explode( ',', $tags );
  61                 $displayTags = [];
  62                 foreach ( $tags as $tag ) {
  63                         if ( !$tag ) {
  64                                 continue;
  65                         }
  66                         $description = self::tagDescription( $tag, $context );
  67                         if ( $description === false ) {
  68                                 continue;
  69                         }
  70                         $displayTags[] = Xml::tags(
  71                                 'span',
  72                                 [ 'class' => 'mw-tag-marker ' .
  73                                                                 Sanitizer::escapeClass( "mw-tag-marker-$tag" ) ],
  74                                 $description
  75                         );
  76                         $classes[] = Sanitizer::escapeClass( "mw-tag-$tag" );
  77                 }
  78
  79                 if ( !$displayTags ) {
  80                         return [ '', [] ];
  81                 }
  82
  83                 $markers = $context->msg( 'tag-list-wrapper' )
  84                         ->numParams( count( $displayTags ) )
  85                         ->rawParams( $context->getLanguage()->commaList( $displayTags ) )
  86                         ->parse();
  87                 $markers = Xml::tags( 'span', [ 'class' => 'mw-tag-markers' ], $markers );
  88
  89                 return [ $markers, $classes ];
  90         }
  91
  92         /**
  93          * Get a short description for a tag.
  94          *
  95          * Checks if message key "mediawiki:tag-$tag" exists. If it does not,
  96          * returns the HTML-escaped tag name. Uses the message if the message
  97          * exists, provided it is not disabled. If the message is disabled,
  98          * we consider the tag hidden, and return false.
  99          *
 100          * @param string $tag Tag
 101          * @param IContextSource $context
 102          * @return string|bool Tag description or false if tag is to be hidden.
 103          * @since 1.25 Returns false if tag is to be hidden.
 104          */
 105         public static function tagDescription( $tag, IContextSource $context ) {
 106                 $msg = $context->msg( "tag-$tag" );
 107                 if ( !$msg->exists() ) {
 108                         // No such message, so return the HTML-escaped tag name.
 109                         return htmlspecialchars( $tag );
 110                 }
 111                 if ( $msg->isDisabled() ) {
 112                         // The message exists but is disabled, hide the tag.
 113                         return false;
 114                 }
 115
 116                 // Message exists and isn't disabled, use it.
 117                 return $msg->parse();
 118         }
 119
 120         /**
 121          * Add tags to a change given its rc_id, rev_id and/or log_id
 122          *
 123          * @param string|string[] $tags Tags to add to the change
 124          * @param int|null $rc_id The rc_id of the change to add the tags to
 125          * @param int|null $rev_id The rev_id of the change to add the tags to
 126          * @param int|null $log_id The log_id of the change to add the tags to
 127          * @param string $params Params to put in the ct_params field of table 'change_tag'
 128          * @param RecentChange|null $rc Recent change, in case the tagging accompanies the action
 129          * (this should normally be the case)
 130          *
 131          * @throws MWException
 132          * @return bool False if no changes are made, otherwise true
 133          */
 134         public static function addTags( $tags, $rc_id = null, $rev_id = null,
 135                 $log_id = null, $params = null, RecentChange $rc = null
 136         ) {
 137                 $result = self::updateTags( $tags, null, $rc_id, $rev_id, $log_id, $params, $rc );
 138                 return (bool)$result[0];
 139         }
 140
 141         /**
 142          * Add and remove tags to/from a change given its rc_id, rev_id and/or log_id,
 143          * without verifying that the tags exist or are valid. If a tag is present in
 144          * both $tagsToAdd and $tagsToRemove, it will be removed.
 145          *
 146          * This function should only be used by extensions to manipulate tags they
 147          * have registered using the ListDefinedTags hook. When dealing with user
 148          * input, call updateTagsWithChecks() instead.
 149          *
 150          * @param string|array|null $tagsToAdd Tags to add to the change
 151          * @param string|array|null $tagsToRemove Tags to remove from the change
 152          * @param int|null &$rc_id The rc_id of the change to add the tags to.
 153          * Pass a variable whose value is null if the rc_id is not relevant or unknown.
 154          * @param int|null &$rev_id The rev_id of the change to add the tags to.
 155          * Pass a variable whose value is null if the rev_id is not relevant or unknown.
 156          * @param int|null &$log_id The log_id of the change to add the tags to.
 157          * Pass a variable whose value is null if the log_id is not relevant or unknown.
 158          * @param string $params Params to put in the ct_params field of table
 159          * 'change_tag' when adding tags
 160          * @param RecentChange|null $rc Recent change being tagged, in case the tagging accompanies
 161          * the action
 162          * @param User|null $user Tagging user, in case the tagging is subsequent to the tagged action
 163          *
 164          * @throws MWException When $rc_id, $rev_id and $log_id are all null
 165          * @return array Index 0 is an array of tags actually added, index 1 is an
 166          * array of tags actually removed, index 2 is an array of tags present on the
 167          * revision or log entry before any changes were made
 168          *
 169          * @since 1.25
 170          */
 171         public static function updateTags( $tagsToAdd, $tagsToRemove, &$rc_id = null,
 172                 &$rev_id = null, &$log_id = null, $params = null, RecentChange $rc = null,
 173                 User $user = null
 174         ) {
 175
 176                 $tagsToAdd = array_filter( (array)$tagsToAdd ); // Make sure we're submitting all tags...
 177                 $tagsToRemove = array_filter( (array)$tagsToRemove );
 178
 179                 if ( !$rc_id && !$rev_id && !$log_id ) {
 180                         throw new MWException( 'At least one of: RCID, revision ID, and log ID MUST be ' .
 181                                 'specified when adding or removing a tag from a change!' );
 182                 }
 183
 184                 $dbw = wfGetDB( DB_MASTER );
 185
 186                 // Might as well look for rcids and so on.
 187                 if ( !$rc_id ) {
 188                         // Info might be out of date, somewhat fractionally, on replica DB.
 189                         // LogEntry/LogPage and WikiPage match rev/log/rc timestamps,
 190                         // so use that relation to avoid full table scans.
 191                         if ( $log_id ) {
 192                                 $rc_id = $dbw->selectField(
 193                                         [ 'logging', 'recentchanges' ],
 194                                         'rc_id',
 195                                         [
 196                                                 'log_id' => $log_id,
 197                                                 'rc_timestamp = log_timestamp',
 198                                                 'rc_logid = log_id'
 199                                         ],
 200                                         __METHOD__
 201                                 );
 202                         } elseif ( $rev_id ) {
 203                                 $rc_id = $dbw->selectField(
 204                                         [ 'revision', 'recentchanges' ],
 205                                         'rc_id',
 206                                         [
 207                                                 'rev_id' => $rev_id,
 208                                                 'rc_timestamp = rev_timestamp',
 209                                                 'rc_this_oldid = rev_id'
 210                                         ],
 211                                         __METHOD__
 212                                 );
 213                         }
 214                 } elseif ( !$log_id && !$rev_id ) {
 215                         // Info might be out of date, somewhat fractionally, on replica DB.
 216                         $log_id = $dbw->selectField(
 217                                 'recentchanges',
 218                                 'rc_logid',
 219                                 [ 'rc_id' => $rc_id ],
 220                                 __METHOD__
 221                         );
 222                         $rev_id = $dbw->selectField(
 223                                 'recentchanges',
 224                                 'rc_this_oldid',
 225                                 [ 'rc_id' => $rc_id ],
 226                                 __METHOD__
 227                         );
 228                 }
 229
 230                 if ( $log_id && !$rev_id ) {
 231                         $rev_id = $dbw->selectField(
 232                                 'log_search',
 233                                 'ls_value',
 234                                 [ 'ls_field' => 'associated_rev_id', 'ls_log_id' => $log_id ],
 235                                 __METHOD__
 236                         );
 237                 } elseif ( !$log_id && $rev_id ) {
 238                         $log_id = $dbw->selectField(
 239                                 'log_search',
 240                                 'ls_log_id',
 241                                 [ 'ls_field' => 'associated_rev_id', 'ls_value' => $rev_id ],
 242                                 __METHOD__
 243                         );
 244                 }
 245
 246                 // update the tag_summary row
 247                 $prevTags = [];
 248                 if ( !self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $rc_id, $rev_id,
 249                         $log_id, $prevTags ) ) {
 250
 251                         // nothing to do
 252                         return [ [], [], $prevTags ];
 253                 }
 254
 255                 // insert a row into change_tag for each new tag
 256                 if ( count( $tagsToAdd ) ) {
 257                         $tagsRows = [];
 258                         foreach ( $tagsToAdd as $tag ) {
 259                                 // Filter so we don't insert NULLs as zero accidentally.
 260                                 // Keep in mind that $rc_id === null means "I don't care/know about the
 261                                 // rc_id, just delete $tag on this revision/log entry". It doesn't
 262                                 // mean "only delete tags on this revision/log WHERE rc_id IS NULL".
 263                                 $tagsRows[] = array_filter(
 264                                         [
 265                                                 'ct_tag' => $tag,
 266                                                 'ct_rc_id' => $rc_id,
 267                                                 'ct_log_id' => $log_id,
 268                                                 'ct_rev_id' => $rev_id,
 269                                                 'ct_params' => $params
 270                                         ]
 271                                 );
 272                         }
 273
 274                         $dbw->insert( 'change_tag', $tagsRows, __METHOD__, [ 'IGNORE' ] );
 275                 }
 276
 277                 // delete from change_tag
 278                 if ( count( $tagsToRemove ) ) {
 279                         foreach ( $tagsToRemove as $tag ) {
 280                                 $conds = array_filter(
 281                                         [
 282                                                 'ct_tag' => $tag,
 283                                                 'ct_rc_id' => $rc_id,
 284                                                 'ct_log_id' => $log_id,
 285                                                 'ct_rev_id' => $rev_id
 286                                         ]
 287                                 );
 288                                 $dbw->delete( 'change_tag', $conds, __METHOD__ );
 289                         }
 290                 }
 291
 292                 self::purgeTagUsageCache();
 293
 294                 Hooks::run( 'ChangeTagsAfterUpdateTags', [ $tagsToAdd, $tagsToRemove, $prevTags,
 295                         $rc_id, $rev_id, $log_id, $params, $rc, $user ] );
 296
 297                 return [ $tagsToAdd, $tagsToRemove, $prevTags ];
 298         }
 299
 300         /**
 301          * Adds or removes a given set of tags to/from the relevant row of the
 302          * tag_summary table. Modifies the tagsToAdd and tagsToRemove arrays to
 303          * reflect the tags that were actually added and/or removed.
 304          *
 305          * @param array &$tagsToAdd
 306          * @param array &$tagsToRemove If a tag is present in both $tagsToAdd and
 307          * $tagsToRemove, it will be removed
 308          * @param int|null $rc_id Null if not known or not applicable
 309          * @param int|null $rev_id Null if not known or not applicable
 310          * @param int|null $log_id Null if not known or not applicable
 311          * @param array &$prevTags Optionally outputs a list of the tags that were
 312          * in the tag_summary row to begin with
 313          * @return bool True if any modifications were made, otherwise false
 314          * @since 1.25
 315          */
 316         protected static function updateTagSummaryRow( &$tagsToAdd, &$tagsToRemove,
 317                 $rc_id, $rev_id, $log_id, &$prevTags = [] ) {
 318
 319                 $dbw = wfGetDB( DB_MASTER );
 320
 321                 $tsConds = array_filter( [
 322                         'ts_rc_id' => $rc_id,
 323                         'ts_rev_id' => $rev_id,
 324                         'ts_log_id' => $log_id
 325                 ] );
 326
 327                 // Can't both add and remove a tag at the same time...
 328                 $tagsToAdd = array_diff( $tagsToAdd, $tagsToRemove );
 329
 330                 // Update the summary row.
 331                 // $prevTags can be out of date on replica DBs, especially when addTags is called consecutively,
 332                 // causing loss of tags added recently in tag_summary table.
 333                 $prevTags = $dbw->selectField( 'tag_summary', 'ts_tags', $tsConds, __METHOD__ );
 334                 $prevTags = $prevTags ? $prevTags : '';
 335                 $prevTags = array_filter( explode( ',', $prevTags ) );
 336
 337                 // add tags
 338                 $tagsToAdd = array_values( array_diff( $tagsToAdd, $prevTags ) );
 339                 $newTags = array_unique( array_merge( $prevTags, $tagsToAdd ) );
 340
 341                 // remove tags
 342                 $tagsToRemove = array_values( array_intersect( $tagsToRemove, $newTags ) );
 343                 $newTags = array_values( array_diff( $newTags, $tagsToRemove ) );
 344
 345                 sort( $prevTags );
 346                 sort( $newTags );
 347                 if ( $prevTags == $newTags ) {
 348                         // No change.
 349                         return false;
 350                 }
 351
 352                 if ( !$newTags ) {
 353                         // no tags left, so delete the row altogether
 354                         $dbw->delete( 'tag_summary', $tsConds, __METHOD__ );
 355                 } else {
 356                         $dbw->replace( 'tag_summary',
 357                                 [ 'ts_rev_id', 'ts_rc_id', 'ts_log_id' ],
 358                                 array_filter( array_merge( $tsConds, [ 'ts_tags' => implode( ',', $newTags ) ] ) ),
 359                                 __METHOD__
 360                         );
 361                 }
 362
 363                 return true;
 364         }
 365
 366         /**
 367          * Helper function to generate a fatal status with a 'not-allowed' type error.
 368          *
 369          * @param string $msgOne Message key to use in the case of one tag
 370          * @param string $msgMulti Message key to use in the case of more than one tag
 371          * @param array $tags Restricted tags (passed as $1 into the message, count of
 372          * $tags passed as $2)
 373          * @return Status
 374          * @since 1.25
 375          */
 376         protected static function restrictedTagError( $msgOne, $msgMulti, $tags ) {
 377                 $lang = RequestContext::getMain()->getLanguage();
 378                 $count = count( $tags );
 379                 return Status::newFatal( ( $count > 1 ) ? $msgMulti : $msgOne,
 380                         $lang->commaList( $tags ), $count );
 381         }
 382
 383         /**
 384          * Is it OK to allow the user to apply all the specified tags at the same time
 385          * as they edit/make the change?
 386          *
 387          * @param array $tags Tags that you are interested in applying
 388          * @param User|null $user User whose permission you wish to check, or null if
 389          * you don't care (e.g. maintenance scripts)
 390          * @return Status
 391          * @since 1.25
 392          */
 393         public static function canAddTagsAccompanyingChange( array $tags,
 394                 User $user = null ) {
 395
 396                 if ( !is_null( $user ) ) {
 397                         if ( !$user->isAllowed( 'applychangetags' ) ) {
 398                                 return Status::newFatal( 'tags-apply-no-permission' );
 399                         } elseif ( $user->isBlocked() ) {
 400                                 return Status::newFatal( 'tags-apply-blocked' );
 401                         }
 402                 }
 403
 404                 // to be applied, a tag has to be explicitly defined
 405                 // @todo Allow extensions to define tags that can be applied by users...
 406                 $allowedTags = self::listExplicitlyDefinedTags();
 407                 $disallowedTags = array_diff( $tags, $allowedTags );
 408                 if ( $disallowedTags ) {
 409                         return self::restrictedTagError( 'tags-apply-not-allowed-one',
 410                                 'tags-apply-not-allowed-multi', $disallowedTags );
 411                 }
 412
 413                 return Status::newGood();
 414         }
 415
 416         /**
 417          * Adds tags to a given change, checking whether it is allowed first, but
 418          * without adding a log entry. Useful for cases where the tag is being added
 419          * along with the action that generated the change (e.g. tagging an edit as
 420          * it is being made).
 421          *
 422          * Extensions should not use this function, unless directly handling a user
 423          * request to add a particular tag. Normally, extensions should call
 424          * ChangeTags::updateTags() instead.
 425          *
 426          * @param array $tags Tags to apply
 427          * @param int|null $rc_id The rc_id of the change to add the tags to
 428          * @param int|null $rev_id The rev_id of the change to add the tags to
 429          * @param int|null $log_id The log_id of the change to add the tags to
 430          * @param string $params Params to put in the ct_params field of table
 431          * 'change_tag' when adding tags
 432          * @param User $user Who to give credit for the action
 433          * @return Status
 434          * @since 1.25
 435          */
 436         public static function addTagsAccompanyingChangeWithChecks(
 437                 array $tags, $rc_id, $rev_id, $log_id, $params, User $user
 438         ) {
 439
 440                 // are we allowed to do this?
 441                 $result = self::canAddTagsAccompanyingChange( $tags, $user );
 442                 if ( !$result->isOK() ) {
 443                         $result->value = null;
 444                         return $result;
 445                 }
 446
 447                 // do it!
 448                 self::addTags( $tags, $rc_id, $rev_id, $log_id, $params );
 449
 450                 return Status::newGood( true );
 451         }
 452
 453         /**
 454          * Is it OK to allow the user to adds and remove the given tags tags to/from a
 455          * change?
 456          *
 457          * @param array $tagsToAdd Tags that you are interested in adding
 458          * @param array $tagsToRemove Tags that you are interested in removing
 459          * @param User|null $user User whose permission you wish to check, or null if
 460          * you don't care (e.g. maintenance scripts)
 461          * @return Status
 462          * @since 1.25
 463          */
 464         public static function canUpdateTags( array $tagsToAdd, array $tagsToRemove,
 465                 User $user = null ) {
 466
 467                 if ( !is_null( $user ) ) {
 468                         if ( !$user->isAllowed( 'changetags' ) ) {
 469                                 return Status::newFatal( 'tags-update-no-permission' );
 470                         } elseif ( $user->isBlocked() ) {
 471                                 return Status::newFatal( 'tags-update-blocked' );
 472                         }
 473                 }
 474
 475                 if ( $tagsToAdd ) {
 476                         // to be added, a tag has to be explicitly defined
 477                         // @todo Allow extensions to define tags that can be applied by users...
 478                         $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
 479                         $diff = array_diff( $tagsToAdd, $explicitlyDefinedTags );
 480                         if ( $diff ) {
 481                                 return self::restrictedTagError( 'tags-update-add-not-allowed-one',
 482                                         'tags-update-add-not-allowed-multi', $diff );
 483                         }
 484                 }
 485
 486                 if ( $tagsToRemove ) {
 487                         // to be removed, a tag must not be defined by an extension, or equivalently it
 488                         // has to be either explicitly defined or not defined at all
 489                         // (assuming no edge case of a tag both explicitly-defined and extension-defined)
 490                         $softwareDefinedTags = self::listSoftwareDefinedTags();
 491                         $intersect = array_intersect( $tagsToRemove, $softwareDefinedTags );
 492                         if ( $intersect ) {
 493                                 return self::restrictedTagError( 'tags-update-remove-not-allowed-one',
 494                                         'tags-update-remove-not-allowed-multi', $intersect );
 495                         }
 496                 }
 497
 498                 return Status::newGood();
 499         }
 500
 501         /**
 502          * Adds and/or removes tags to/from a given change, checking whether it is
 503          * allowed first, and adding a log entry afterwards.
 504          *
 505          * Includes a call to ChangeTag::canUpdateTags(), so your code doesn't need
 506          * to do that. However, it doesn't check whether the *_id parameters are a
 507          * valid combination. That is up to you to enforce. See ApiTag::execute() for
 508          * an example.
 509          *
 510          * @param array|null $tagsToAdd If none, pass array() or null
 511          * @param array|null $tagsToRemove If none, pass array() or null
 512          * @param int|null $rc_id The rc_id of the change to add the tags to
 513          * @param int|null $rev_id The rev_id of the change to add the tags to
 514          * @param int|null $log_id The log_id of the change to add the tags to
 515          * @param string $params Params to put in the ct_params field of table
 516          * 'change_tag' when adding tags
 517          * @param string $reason Comment for the log
 518          * @param User $user Who to give credit for the action
 519          * @return Status If successful, the value of this Status object will be an
 520          * object (stdClass) with the following fields:
 521          *  - logId: the ID of the added log entry, or null if no log entry was added
 522          *    (i.e. no operation was performed)
 523          *  - addedTags: an array containing the tags that were actually added
 524          *  - removedTags: an array containing the tags that were actually removed
 525          * @since 1.25
 526          */
 527         public static function updateTagsWithChecks( $tagsToAdd, $tagsToRemove,
 528                 $rc_id, $rev_id, $log_id, $params, $reason, User $user ) {
 529
 530                 if ( is_null( $tagsToAdd ) ) {
 531                         $tagsToAdd = [];
 532                 }
 533                 if ( is_null( $tagsToRemove ) ) {
 534                         $tagsToRemove = [];
 535                 }
 536                 if ( !$tagsToAdd && !$tagsToRemove ) {
 537                         // no-op, don't bother
 538                         return Status::newGood( (object)[
 539                                 'logId' => null,
 540                                 'addedTags' => [],
 541                                 'removedTags' => [],
 542                         ] );
 543                 }
 544
 545                 // are we allowed to do this?
 546                 $result = self::canUpdateTags( $tagsToAdd, $tagsToRemove, $user );
 547                 if ( !$result->isOK() ) {
 548                         $result->value = null;
 549                         return $result;
 550                 }
 551
 552                 // basic rate limiting
 553                 if ( $user->pingLimiter( 'changetag' ) ) {
 554                         return Status::newFatal( 'actionthrottledtext' );
 555                 }
 556
 557                 // do it!
 558                 list( $tagsAdded, $tagsRemoved, $initialTags ) = self::updateTags( $tagsToAdd,
 559                         $tagsToRemove, $rc_id, $rev_id, $log_id, $params, null, $user );
 560                 if ( !$tagsAdded && !$tagsRemoved ) {
 561                         // no-op, don't log it
 562                         return Status::newGood( (object)[
 563                                 'logId' => null,
 564                                 'addedTags' => [],
 565                                 'removedTags' => [],
 566                         ] );
 567                 }
 568
 569                 // log it
 570                 $logEntry = new ManualLogEntry( 'tag', 'update' );
 571                 $logEntry->setPerformer( $user );
 572                 $logEntry->setComment( $reason );
 573
 574                 // find the appropriate target page
 575                 if ( $rev_id ) {
 576                         $rev = Revision::newFromId( $rev_id );
 577                         if ( $rev ) {
 578                                 $logEntry->setTarget( $rev->getTitle() );
 579                         }
 580                 } elseif ( $log_id ) {
 581                         // This function is from revision deletion logic and has nothing to do with
 582                         // change tags, but it appears to be the only other place in core where we
 583                         // perform logged actions on log items.
 584                         $logEntry->setTarget( RevDelLogList::suggestTarget( null, [ $log_id ] ) );
 585                 }
 586
 587                 if ( !$logEntry->getTarget() ) {
 588                         // target is required, so we have to set something
 589                         $logEntry->setTarget( SpecialPage::getTitleFor( 'Tags' ) );
 590                 }
 591
 592                 $logParams = [
 593                         '4::revid' => $rev_id,
 594                         '5::logid' => $log_id,
 595                         '6:list:tagsAdded' => $tagsAdded,
 596                         '7:number:tagsAddedCount' => count( $tagsAdded ),
 597                         '8:list:tagsRemoved' => $tagsRemoved,
 598                         '9:number:tagsRemovedCount' => count( $tagsRemoved ),
 599                         'initialTags' => $initialTags,
 600                 ];
 601                 $logEntry->setParameters( $logParams );
 602                 $logEntry->setRelations( [ 'Tag' => array_merge( $tagsAdded, $tagsRemoved ) ] );
 603
 604                 $dbw = wfGetDB( DB_MASTER );
 605                 $logId = $logEntry->insert( $dbw );
 606                 // Only send this to UDP, not RC, similar to patrol events
 607                 $logEntry->publish( $logId, 'udp' );
 608
 609                 return Status::newGood( (object)[
 610                         'logId' => $logId,
 611                         'addedTags' => $tagsAdded,
 612                         'removedTags' => $tagsRemoved,
 613                 ] );
 614         }
 615
 616         /**
 617          * Applies all tags-related changes to a query.
 618          * Handles selecting tags, and filtering.
 619          * Needs $tables to be set up properly, so we can figure out which join conditions to use.
 620          *
 621          * @param string|array $tables Table names, see Database::select
 622          * @param string|array $fields Fields used in query, see Database::select
 623          * @param string|array $conds Conditions used in query, see Database::select
 624          * @param array $join_conds Join conditions, see Database::select
 625          * @param array $options Options, see Database::select
 626          * @param bool|string $filter_tag Tag to select on
 627          *
 628          * @throws MWException When unable to determine appropriate JOIN condition for tagging
 629          */
 630         public static function modifyDisplayQuery( &$tables, &$fields, &$conds,
 631                                                                                 &$join_conds, &$options, $filter_tag = false ) {
 632                 global $wgRequest, $wgUseTagFilter;
 633
 634                 if ( $filter_tag === false ) {
 635                         $filter_tag = $wgRequest->getVal( 'tagfilter' );
 636                 }
 637
 638                 // Figure out which conditions can be done.
 639                 if ( in_array( 'recentchanges', $tables ) ) {
 640                         $join_cond = 'ct_rc_id=rc_id';
 641                 } elseif ( in_array( 'logging', $tables ) ) {
 642                         $join_cond = 'ct_log_id=log_id';
 643                 } elseif ( in_array( 'revision', $tables ) ) {
 644                         $join_cond = 'ct_rev_id=rev_id';
 645                 } elseif ( in_array( 'archive', $tables ) ) {
 646                         $join_cond = 'ct_rev_id=ar_rev_id';
 647                 } else {
 648                         throw new MWException( 'Unable to determine appropriate JOIN condition for tagging.' );
 649                 }
 650
 651                 $fields['ts_tags'] = wfGetDB( DB_REPLICA )->buildGroupConcatField(
 652                         ',', 'change_tag', 'ct_tag', $join_cond
 653                 );
 654
 655                 if ( $wgUseTagFilter && $filter_tag ) {
 656                         // Somebody wants to filter on a tag.
 657                         // Add an INNER JOIN on change_tag
 658
 659                         $tables[] = 'change_tag';
 660                         $join_conds['change_tag'] = [ 'INNER JOIN', $join_cond ];
 661                         $conds['ct_tag'] = $filter_tag;
 662                 }
 663         }
 664
 665         /**
 666          * Build a text box to select a change tag
 667          *
 668          * @param string $selected Tag to select by default
 669          * @param bool $ooui Use an OOUI TextInputWidget as selector instead of a non-OOUI input field
 670          *        You need to call OutputPage::enableOOUI() yourself.
 671          * @return array an array of (label, selector)
 672          */
 673         public static function buildTagFilterSelector( $selected = '', $ooui = false ) {
 674                 global $wgUseTagFilter;
 675
 676                 if ( !$wgUseTagFilter || !count( self::listDefinedTags() ) ) {
 677                         return [];
 678                 }
 679
 680                 $data = [
 681                         Html::rawElement(
 682                                 'label',
 683                                 [ 'for' => 'tagfilter' ],
 684                                 wfMessage( 'tag-filter' )->parse()
 685                         )
 686                 ];
 687
 688                 if ( $ooui ) {
 689                         $data[] = new OOUI\TextInputWidget( [
 690                                 'id' => 'tagfilter',
 691                                 'name' => 'tagfilter',
 692                                 'value' => $selected,
 693                                 'classes' => 'mw-tagfilter-input',
 694                         ] );
 695                 } else {
 696                         $data[] = Xml::input(
 697                                 'tagfilter',
 698                                 20,
 699                                 $selected,
 700                                 [ 'class' => 'mw-tagfilter-input mw-ui-input mw-ui-input-inline', 'id' => 'tagfilter' ]
 701                         );
 702                 }
 703
 704                 return $data;
 705         }
 706
 707         /**
 708          * Defines a tag in the valid_tag table, without checking that the tag name
 709          * is valid.
 710          * Extensions should NOT use this function; they can use the ListDefinedTags
 711          * hook instead.
 712          *
 713          * @param string $tag Tag to create
 714          * @since 1.25
 715          */
 716         public static function defineTag( $tag ) {
 717                 $dbw = wfGetDB( DB_MASTER );
 718                 $dbw->replace( 'valid_tag',
 719                         [ 'vt_tag' ],
 720                         [ 'vt_tag' => $tag ],
 721                         __METHOD__ );
 722
 723                 // clear the memcache of defined tags
 724                 self::purgeTagCacheAll();
 725         }
 726
 727         /**
 728          * Removes a tag from the valid_tag table. The tag may remain in use by
 729          * extensions, and may still show up as 'defined' if an extension is setting
 730          * it from the ListDefinedTags hook.
 731          *
 732          * @param string $tag Tag to remove
 733          * @since 1.25
 734          */
 735         public static function undefineTag( $tag ) {
 736                 $dbw = wfGetDB( DB_MASTER );
 737                 $dbw->delete( 'valid_tag', [ 'vt_tag' => $tag ], __METHOD__ );
 738
 739                 // clear the memcache of defined tags
 740                 self::purgeTagCacheAll();
 741         }
 742
 743         /**
 744          * Writes a tag action into the tag management log.
 745          *
 746          * @param string $action
 747          * @param string $tag
 748          * @param string $reason
 749          * @param User $user Who to attribute the action to
 750          * @param int $tagCount For deletion only, how many usages the tag had before
 751          * it was deleted.
 752          * @return int ID of the inserted log entry
 753          * @since 1.25
 754          */
 755         protected static function logTagManagementAction( $action, $tag, $reason,
 756                 User $user, $tagCount = null ) {
 757
 758                 $dbw = wfGetDB( DB_MASTER );
 759
 760                 $logEntry = new ManualLogEntry( 'managetags', $action );
 761                 $logEntry->setPerformer( $user );
 762                 // target page is not relevant, but it has to be set, so we just put in
 763                 // the title of Special:Tags
 764                 $logEntry->setTarget( Title::newFromText( 'Special:Tags' ) );
 765                 $logEntry->setComment( $reason );
 766
 767                 $params = [ '4::tag' => $tag ];
 768                 if ( !is_null( $tagCount ) ) {
 769                         $params['5:number:count'] = $tagCount;
 770                 }
 771                 $logEntry->setParameters( $params );
 772                 $logEntry->setRelations( [ 'Tag' => $tag ] );
 773
 774                 $logId = $logEntry->insert( $dbw );
 775                 $logEntry->publish( $logId );
 776                 return $logId;
 777         }
 778
 779         /**
 780          * Is it OK to allow the user to activate this tag?
 781          *
 782          * @param string $tag Tag that you are interested in activating
 783          * @param User|null $user User whose permission you wish to check, or null if
 784          * you don't care (e.g. maintenance scripts)
 785          * @return Status
 786          * @since 1.25
 787          */
 788         public static function canActivateTag( $tag, User $user = null ) {
 789                 if ( !is_null( $user ) ) {
 790                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 791                                 return Status::newFatal( 'tags-manage-no-permission' );
 792                         } elseif ( $user->isBlocked() ) {
 793                                 return Status::newFatal( 'tags-manage-blocked' );
 794                         }
 795                 }
 796
 797                 // defined tags cannot be activated (a defined tag is either extension-
 798                 // defined, in which case the extension chooses whether or not to active it;
 799                 // or user-defined, in which case it is considered active)
 800                 $definedTags = self::listDefinedTags();
 801                 if ( in_array( $tag, $definedTags ) ) {
 802                         return Status::newFatal( 'tags-activate-not-allowed', $tag );
 803                 }
 804
 805                 // non-existing tags cannot be activated
 806                 $tagUsage = self::tagUsageStatistics();
 807                 if ( !isset( $tagUsage[$tag] ) ) { // we already know the tag is undefined
 808                         return Status::newFatal( 'tags-activate-not-found', $tag );
 809                 }
 810
 811                 return Status::newGood();
 812         }
 813
 814         /**
 815          * Activates a tag, checking whether it is allowed first, and adding a log
 816          * entry afterwards.
 817          *
 818          * Includes a call to ChangeTag::canActivateTag(), so your code doesn't need
 819          * to do that.
 820          *
 821          * @param string $tag
 822          * @param string $reason
 823          * @param User $user Who to give credit for the action
 824          * @param bool $ignoreWarnings Can be used for API interaction, default false
 825          * @return Status If successful, the Status contains the ID of the added log
 826          * entry as its value
 827          * @since 1.25
 828          */
 829         public static function activateTagWithChecks( $tag, $reason, User $user,
 830                 $ignoreWarnings = false ) {
 831
 832                 // are we allowed to do this?
 833                 $result = self::canActivateTag( $tag, $user );
 834                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
 835                         $result->value = null;
 836                         return $result;
 837                 }
 838
 839                 // do it!
 840                 self::defineTag( $tag );
 841
 842                 // log it
 843                 $logId = self::logTagManagementAction( 'activate', $tag, $reason, $user );
 844                 return Status::newGood( $logId );
 845         }
 846
 847         /**
 848          * Is it OK to allow the user to deactivate this tag?
 849          *
 850          * @param string $tag Tag that you are interested in deactivating
 851          * @param User|null $user User whose permission you wish to check, or null if
 852          * you don't care (e.g. maintenance scripts)
 853          * @return Status
 854          * @since 1.25
 855          */
 856         public static function canDeactivateTag( $tag, User $user = null ) {
 857                 if ( !is_null( $user ) ) {
 858                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 859                                 return Status::newFatal( 'tags-manage-no-permission' );
 860                         } elseif ( $user->isBlocked() ) {
 861                                 return Status::newFatal( 'tags-manage-blocked' );
 862                         }
 863                 }
 864
 865                 // only explicitly-defined tags can be deactivated
 866                 $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
 867                 if ( !in_array( $tag, $explicitlyDefinedTags ) ) {
 868                         return Status::newFatal( 'tags-deactivate-not-allowed', $tag );
 869                 }
 870                 return Status::newGood();
 871         }
 872
 873         /**
 874          * Deactivates a tag, checking whether it is allowed first, and adding a log
 875          * entry afterwards.
 876          *
 877          * Includes a call to ChangeTag::canDeactivateTag(), so your code doesn't need
 878          * to do that.
 879          *
 880          * @param string $tag
 881          * @param string $reason
 882          * @param User $user Who to give credit for the action
 883          * @param bool $ignoreWarnings Can be used for API interaction, default false
 884          * @return Status If successful, the Status contains the ID of the added log
 885          * entry as its value
 886          * @since 1.25
 887          */
 888         public static function deactivateTagWithChecks( $tag, $reason, User $user,
 889                 $ignoreWarnings = false ) {
 890
 891                 // are we allowed to do this?
 892                 $result = self::canDeactivateTag( $tag, $user );
 893                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
 894                         $result->value = null;
 895                         return $result;
 896                 }
 897
 898                 // do it!
 899                 self::undefineTag( $tag );
 900
 901                 // log it
 902                 $logId = self::logTagManagementAction( 'deactivate', $tag, $reason, $user );
 903                 return Status::newGood( $logId );
 904         }
 905
 906         /**
 907          * Is it OK to allow the user to create this tag?
 908          *
 909          * @param string $tag Tag that you are interested in creating
 910          * @param User|null $user User whose permission you wish to check, or null if
 911          * you don't care (e.g. maintenance scripts)
 912          * @return Status
 913          * @since 1.25
 914          */
 915         public static function canCreateTag( $tag, User $user = null ) {
 916                 if ( !is_null( $user ) ) {
 917                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 918                                 return Status::newFatal( 'tags-manage-no-permission' );
 919                         } elseif ( $user->isBlocked() ) {
 920                                 return Status::newFatal( 'tags-manage-blocked' );
 921                         }
 922                 }
 923
 924                 // no empty tags
 925                 if ( $tag === '' ) {
 926                         return Status::newFatal( 'tags-create-no-name' );
 927                 }
 928
 929                 // tags cannot contain commas (used as a delimiter in tag_summary table) or
 930                 // slashes (would break tag description messages in MediaWiki namespace)
 931                 if ( strpos( $tag, ',' ) !== false || strpos( $tag, '/' ) !== false ) {
 932                         return Status::newFatal( 'tags-create-invalid-chars' );
 933                 }
 934
 935                 // could the MediaWiki namespace description messages be created?
 936                 $title = Title::makeTitleSafe( NS_MEDIAWIKI, "Tag-$tag-description" );
 937                 if ( is_null( $title ) ) {
 938                         return Status::newFatal( 'tags-create-invalid-title-chars' );
 939                 }
 940
 941                 // does the tag already exist?
 942                 $tagUsage = self::tagUsageStatistics();
 943                 if ( isset( $tagUsage[$tag] ) || in_array( $tag, self::listDefinedTags() ) ) {
 944                         return Status::newFatal( 'tags-create-already-exists', $tag );
 945                 }
 946
 947                 // check with hooks
 948                 $canCreateResult = Status::newGood();
 949                 Hooks::run( 'ChangeTagCanCreate', [ $tag, $user, &$canCreateResult ] );
 950                 return $canCreateResult;
 951         }
 952
 953         /**
 954          * Creates a tag by adding a row to the `valid_tag` table.
 955          *
 956          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
 957          * do that.
 958          *
 959          * @param string $tag
 960          * @param string $reason
 961          * @param User $user Who to give credit for the action
 962          * @param bool $ignoreWarnings Can be used for API interaction, default false
 963          * @return Status If successful, the Status contains the ID of the added log
 964          * entry as its value
 965          * @since 1.25
 966          */
 967         public static function createTagWithChecks( $tag, $reason, User $user,
 968                 $ignoreWarnings = false ) {
 969
 970                 // are we allowed to do this?
 971                 $result = self::canCreateTag( $tag, $user );
 972                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
 973                         $result->value = null;
 974                         return $result;
 975                 }
 976
 977                 // do it!
 978                 self::defineTag( $tag );
 979
 980                 // log it
 981                 $logId = self::logTagManagementAction( 'create', $tag, $reason, $user );
 982                 return Status::newGood( $logId );
 983         }
 984
 985         /**
 986          * Permanently removes all traces of a tag from the DB. Good for removing
 987          * misspelt or temporary tags.
 988          *
 989          * This function should be directly called by maintenance scripts only, never
 990          * by user-facing code. See deleteTagWithChecks() for functionality that can
 991          * safely be exposed to users.
 992          *
 993          * @param string $tag Tag to remove
 994          * @return Status The returned status will be good unless a hook changed it
 995          * @since 1.25
 996          */
 997         public static function deleteTagEverywhere( $tag ) {
 998                 $dbw = wfGetDB( DB_MASTER );
 999                 $dbw->startAtomic( __METHOD__ );
1000
1001                 // delete from valid_tag
1002                 self::undefineTag( $tag );
1003
1004                 // find out which revisions use this tag, so we can delete from tag_summary
1005                 $result = $dbw->select( 'change_tag',
1006                         [ 'ct_rc_id', 'ct_log_id', 'ct_rev_id', 'ct_tag' ],
1007                         [ 'ct_tag' => $tag ],
1008                         __METHOD__ );
1009                 foreach ( $result as $row ) {
1010                         // remove the tag from the relevant row of tag_summary
1011                         $tagsToAdd = [];
1012                         $tagsToRemove = [ $tag ];
1013                         self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $row->ct_rc_id,
1014                                 $row->ct_rev_id, $row->ct_log_id );
1015                 }
1016
1017                 // delete from change_tag
1018                 $dbw->delete( 'change_tag', [ 'ct_tag' => $tag ], __METHOD__ );
1019
1020                 $dbw->endAtomic( __METHOD__ );
1021
1022                 // give extensions a chance
1023                 $status = Status::newGood();
1024                 Hooks::run( 'ChangeTagAfterDelete', [ $tag, &$status ] );
1025                 // let's not allow error results, as the actual tag deletion succeeded
1026                 if ( !$status->isOK() ) {
1027                         wfDebug( 'ChangeTagAfterDelete error condition downgraded to warning' );
1028                         $status->setOK( true );
1029                 }
1030
1031                 // clear the memcache of defined tags
1032                 self::purgeTagCacheAll();
1033
1034                 return $status;
1035         }
1036
1037         /**
1038          * Is it OK to allow the user to delete this tag?
1039          *
1040          * @param string $tag Tag that you are interested in deleting
1041          * @param User|null $user User whose permission you wish to check, or null if
1042          * you don't care (e.g. maintenance scripts)
1043          * @return Status
1044          * @since 1.25
1045          */
1046         public static function canDeleteTag( $tag, User $user = null ) {
1047                 $tagUsage = self::tagUsageStatistics();
1048
1049                 if ( !is_null( $user ) ) {
1050                         if ( !$user->isAllowed( 'deletechangetags' ) ) {
1051                                 return Status::newFatal( 'tags-delete-no-permission' );
1052                         } elseif ( $user->isBlocked() ) {
1053                                 return Status::newFatal( 'tags-manage-blocked' );
1054                         }
1055                 }
1056
1057                 if ( !isset( $tagUsage[$tag] ) && !in_array( $tag, self::listDefinedTags() ) ) {
1058                         return Status::newFatal( 'tags-delete-not-found', $tag );
1059                 }
1060
1061                 if ( isset( $tagUsage[$tag] ) && $tagUsage[$tag] > self::MAX_DELETE_USES ) {
1062                         return Status::newFatal( 'tags-delete-too-many-uses', $tag, self::MAX_DELETE_USES );
1063                 }
1064
1065                 $softwareDefined = self::listSoftwareDefinedTags();
1066                 if ( in_array( $tag, $softwareDefined ) ) {
1067                         // extension-defined tags can't be deleted unless the extension
1068                         // specifically allows it
1069                         $status = Status::newFatal( 'tags-delete-not-allowed' );
1070                 } else {
1071                         // user-defined tags are deletable unless otherwise specified
1072                         $status = Status::newGood();
1073                 }
1074
1075                 Hooks::run( 'ChangeTagCanDelete', [ $tag, $user, &$status ] );
1076                 return $status;
1077         }
1078
1079         /**
1080          * Deletes a tag, checking whether it is allowed first, and adding a log entry
1081          * afterwards.
1082          *
1083          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
1084          * do that.
1085          *
1086          * @param string $tag
1087          * @param string $reason
1088          * @param User $user Who to give credit for the action
1089          * @param bool $ignoreWarnings Can be used for API interaction, default false
1090          * @return Status If successful, the Status contains the ID of the added log
1091          * entry as its value
1092          * @since 1.25
1093          */
1094         public static function deleteTagWithChecks( $tag, $reason, User $user,
1095                 $ignoreWarnings = false ) {
1096
1097                 // are we allowed to do this?
1098                 $result = self::canDeleteTag( $tag, $user );
1099                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1100                         $result->value = null;
1101                         return $result;
1102                 }
1103
1104                 // store the tag usage statistics
1105                 $tagUsage = self::tagUsageStatistics();
1106                 $hitcount = isset( $tagUsage[$tag] ) ? $tagUsage[$tag] : 0;
1107
1108                 // do it!
1109                 $deleteResult = self::deleteTagEverywhere( $tag );
1110                 if ( !$deleteResult->isOK() ) {
1111                         return $deleteResult;
1112                 }
1113
1114                 // log it
1115                 $logId = self::logTagManagementAction( 'delete', $tag, $reason, $user, $hitcount );
1116                 $deleteResult->value = $logId;
1117                 return $deleteResult;
1118         }
1119
1120         /**
1121          * Lists those tags which core or extensions report as being "active".
1122          *
1123          * @return array
1124          * @since 1.25
1125          */
1126         public static function listSoftwareActivatedTags() {
1127                 // core active tags
1128                 $tags = self::$coreTags;
1129                 if ( !Hooks::isRegistered( 'ChangeTagsListActive' ) ) {
1130                         return $tags;
1131                 }
1132                 return ObjectCache::getMainWANInstance()->getWithSetCallback(
1133                         wfMemcKey( 'active-tags' ),
1134                         WANObjectCache::TTL_MINUTE * 5,
1135                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1136                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1137
1138                                 // Ask extensions which tags they consider active
1139                                 Hooks::run( 'ChangeTagsListActive', [ &$tags ] );
1140                                 return $tags;
1141                         },
1142                         [
1143                                 'checkKeys' => [ wfMemcKey( 'active-tags' ) ],
1144                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1145                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1146                         ]
1147                 );
1148         }
1149
1150         /**
1151          * @see listSoftwareActivatedTags
1152          * @deprecated since 1.28 call listSoftwareActivatedTags directly
1153          * @return array
1154          */
1155         public static function listExtensionActivatedTags() {
1156                 wfDeprecated( __METHOD__, '1.28' );
1157                 return self::listSoftwareActivatedTags();
1158         }
1159
1160         /**
1161          * Basically lists defined tags which count even if they aren't applied to anything.
1162          * It returns a union of the results of listExplicitlyDefinedTags() and
1163          * listExtensionDefinedTags().
1164          *
1165          * @return string[] Array of strings: tags
1166          */
1167         public static function listDefinedTags() {
1168                 $tags1 = self::listExplicitlyDefinedTags();
1169                 $tags2 = self::listSoftwareDefinedTags();
1170                 return array_values( array_unique( array_merge( $tags1, $tags2 ) ) );
1171         }
1172
1173         /**
1174          * Lists tags explicitly defined in the `valid_tag` table of the database.
1175          * Tags in table 'change_tag' which are not in table 'valid_tag' are not
1176          * included.
1177          *
1178          * Tries memcached first.
1179          *
1180          * @return string[] Array of strings: tags
1181          * @since 1.25
1182          */
1183         public static function listExplicitlyDefinedTags() {
1184                 $fname = __METHOD__;
1185
1186                 return ObjectCache::getMainWANInstance()->getWithSetCallback(
1187                         wfMemcKey( 'valid-tags-db' ),
1188                         WANObjectCache::TTL_MINUTE * 5,
1189                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1190                                 $dbr = wfGetDB( DB_REPLICA );
1191
1192                                 $setOpts += Database::getCacheSetOptions( $dbr );
1193
1194                                 $tags = $dbr->selectFieldValues( 'valid_tag', 'vt_tag', [], $fname );
1195
1196                                 return array_filter( array_unique( $tags ) );
1197                         },
1198                         [
1199                                 'checkKeys' => [ wfMemcKey( 'valid-tags-db' ) ],
1200                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1201                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1202                         ]
1203                 );
1204         }
1205
1206         /**
1207          * Lists tags defined by core or extensions using the ListDefinedTags hook.
1208          * Extensions need only define those tags they deem to be in active use.
1209          *
1210          * Tries memcached first.
1211          *
1212          * @return string[] Array of strings: tags
1213          * @since 1.25
1214          */
1215         public static function listSoftwareDefinedTags() {
1216                 // core defined tags
1217                 $tags = self::$coreTags;
1218                 if ( !Hooks::isRegistered( 'ListDefinedTags' ) ) {
1219                         return $tags;
1220                 }
1221                 return ObjectCache::getMainWANInstance()->getWithSetCallback(
1222                         wfMemcKey( 'valid-tags-hook' ),
1223                         WANObjectCache::TTL_MINUTE * 5,
1224                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1225                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1226
1227                                 Hooks::run( 'ListDefinedTags', [ &$tags ] );
1228                                 return array_filter( array_unique( $tags ) );
1229                         },
1230                         [
1231                                 'checkKeys' => [ wfMemcKey( 'valid-tags-hook' ) ],
1232                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1233                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1234                         ]
1235                 );
1236         }
1237
1238         /**
1239          * Call listSoftwareDefinedTags directly
1240          *
1241          * @see listSoftwareDefinedTags
1242          * @deprecated since 1.28
1243          */
1244         public static function listExtensionDefinedTags() {
1245                 wfDeprecated( __METHOD__, '1.28' );
1246                 return self::listSoftwareDefinedTags();
1247         }
1248
1249         /**
1250          * Invalidates the short-term cache of defined tags used by the
1251          * list*DefinedTags functions, as well as the tag statistics cache.
1252          * @since 1.25
1253          */
1254         public static function purgeTagCacheAll() {
1255                 $cache = ObjectCache::getMainWANInstance();
1256
1257                 $cache->touchCheckKey( wfMemcKey( 'active-tags' ) );
1258                 $cache->touchCheckKey( wfMemcKey( 'valid-tags-db' ) );
1259                 $cache->touchCheckKey( wfMemcKey( 'valid-tags-hook' ) );
1260
1261                 self::purgeTagUsageCache();
1262         }
1263
1264         /**
1265          * Invalidates the tag statistics cache only.
1266          * @since 1.25
1267          */
1268         public static function purgeTagUsageCache() {
1269                 $cache = ObjectCache::getMainWANInstance();
1270
1271                 $cache->touchCheckKey( wfMemcKey( 'change-tag-statistics' ) );
1272         }
1273
1274         /**
1275          * Returns a map of any tags used on the wiki to number of edits
1276          * tagged with them, ordered descending by the hitcount.
1277          * This does not include tags defined somewhere that have never been applied.
1278          *
1279          * Keeps a short-term cache in memory, so calling this multiple times in the
1280          * same request should be fine.
1281          *
1282          * @return array Array of string => int
1283          */
1284         public static function tagUsageStatistics() {
1285                 $fname = __METHOD__;
1286                 return ObjectCache::getMainWANInstance()->getWithSetCallback(
1287                         wfMemcKey( 'change-tag-statistics' ),
1288                         WANObjectCache::TTL_MINUTE * 5,
1289                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1290                                 $dbr = wfGetDB( DB_REPLICA, 'vslow' );
1291
1292                                 $setOpts += Database::getCacheSetOptions( $dbr );
1293
1294                                 $res = $dbr->select(
1295                                         'change_tag',
1296                                         [ 'ct_tag', 'hitcount' => 'count(*)' ],
1297                                         [],
1298                                         $fname,
1299                                         [ 'GROUP BY' => 'ct_tag', 'ORDER BY' => 'hitcount DESC' ]
1300                                 );
1301
1302                                 $out = [];
1303                                 foreach ( $res as $row ) {
1304                                         $out[$row->ct_tag] = $row->hitcount;
1305                                 }
1306
1307                                 return $out;
1308                         },
1309                         [
1310                                 'checkKeys' => [ wfMemcKey( 'change-tag-statistics' ) ],
1311                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1312                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1313                         ]
1314                 );
1315         }
1316
1317         /**
1318          * Indicate whether change tag editing UI is relevant
1319          *
1320          * Returns true if the user has the necessary right and there are any
1321          * editable tags defined.
1322          *
1323          * This intentionally doesn't check "any addable || any deletable", because
1324          * it seems like it would be more confusing than useful if the checkboxes
1325          * suddenly showed up because some abuse filter stopped defining a tag and
1326          * then suddenly disappeared when someone deleted all uses of that tag.
1327          *
1328          * @param User $user
1329          * @return bool
1330          */
1331         public static function showTagEditingUI( User $user ) {
1332                 return $user->isAllowed( 'changetags' ) && (bool)self::listExplicitlyDefinedTags();
1333         }
1334 }