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