includes/changetags/ChangeTags.php

   1 <?php
   2 /**
   3  * Recent changes tagging.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Change tagging
  22  */
  23
  24 use MediaWiki\MediaWikiServices;
  25 use Wikimedia\Rdbms\Database;
  26
  27 class ChangeTags {
  28         /**
  29          * Can't delete tags with more than this many uses. Similar in intent to
  30          * the bigdelete user right
  31          * @todo Use the job queue for tag deletion to avoid this restriction
  32          */
  33         const MAX_DELETE_USES = 5000;
  34
  35         /**
  36          * A list of tags defined and used by MediaWiki itself.
  37          */
  38         private static $definedSoftwareTags = [
  39                 'mw-contentmodelchange',
  40                 'mw-new-redirect',
  41                 'mw-removed-redirect',
  42                 'mw-changed-redirect-target',
  43                 'mw-blank',
  44                 'mw-replace',
  45                 'mw-rollback',
  46                 'mw-undo',
  47         ];
  48
  49         /**
  50          * Loads defined core tags, checks for invalid types (if not array),
  51          * and filters for supported and enabled (if $all is false) tags only.
  52          *
  53          * @param bool $all If true, return all valid defined tags. Otherwise, return only enabled ones.
  54          * @return array Array of all defined/enabled tags.
  55          */
  56         public static function getSoftwareTags( $all = false ) {
  57                 global $wgSoftwareTags;
  58                 $softwareTags = [];
  59
  60                 if ( !is_array( $wgSoftwareTags ) ) {
  61                         wfWarn( 'wgSoftwareTags should be associative array of enabled tags.
  62                         Please refer to documentation for the list of tags you can enable' );
  63                         return $softwareTags;
  64                 }
  65
  66                 $availableSoftwareTags = !$all ?
  67                         array_keys( array_filter( $wgSoftwareTags ) ) :
  68                         array_keys( $wgSoftwareTags );
  69
  70                 $softwareTags = array_intersect(
  71                         $availableSoftwareTags,
  72                         self::$definedSoftwareTags
  73                 );
  74
  75                 return $softwareTags;
  76         }
  77
  78         /**
  79          * Creates HTML for the given tags
  80          *
  81          * @param string $tags Comma-separated list of tags
  82          * @param string $page A label for the type of action which is being displayed,
  83          *   for example: 'history', 'contributions' or 'newpages'
  84          * @param IContextSource|null $context
  85          * @note Even though it takes null as a valid argument, an IContextSource is preferred
  86          *       in a new code, as the null value is subject to change in the future
  87          * @return array Array with two items: (html, classes)
  88          *   - html: String: HTML for displaying the tags (empty string when param $tags is empty)
  89          *   - classes: Array of strings: CSS classes used in the generated html, one class for each tag
  90          */
  91         public static function formatSummaryRow( $tags, $page, IContextSource $context = null ) {
  92                 if ( !$tags ) {
  93                         return [ '', [] ];
  94                 }
  95                 if ( !$context ) {
  96                         $context = RequestContext::getMain();
  97                 }
  98
  99                 $classes = [];
 100
 101                 $tags = explode( ',', $tags );
 102                 $displayTags = [];
 103                 foreach ( $tags as $tag ) {
 104                         if ( !$tag ) {
 105                                 continue;
 106                         }
 107                         $description = self::tagDescription( $tag, $context );
 108                         if ( $description === false ) {
 109                                 continue;
 110                         }
 111                         $displayTags[] = Xml::tags(
 112                                 'span',
 113                                 [ 'class' => 'mw-tag-marker ' .
 114                                                                 Sanitizer::escapeClass( "mw-tag-marker-$tag" ) ],
 115                                 $description
 116                         );
 117                         $classes[] = Sanitizer::escapeClass( "mw-tag-$tag" );
 118                 }
 119
 120                 if ( !$displayTags ) {
 121                         return [ '', [] ];
 122                 }
 123
 124                 $markers = $context->msg( 'tag-list-wrapper' )
 125                         ->numParams( count( $displayTags ) )
 126                         ->rawParams( $context->getLanguage()->commaList( $displayTags ) )
 127                         ->parse();
 128                 $markers = Xml::tags( 'span', [ 'class' => 'mw-tag-markers' ], $markers );
 129
 130                 return [ $markers, $classes ];
 131         }
 132
 133         /**
 134          * Get a short description for a tag.
 135          *
 136          * Checks if message key "mediawiki:tag-$tag" exists. If it does not,
 137          * returns the HTML-escaped tag name. Uses the message if the message
 138          * exists, provided it is not disabled. If the message is disabled,
 139          * we consider the tag hidden, and return false.
 140          *
 141          * @param string $tag
 142          * @param IContextSource $context
 143          * @return string|bool Tag description or false if tag is to be hidden.
 144          * @since 1.25 Returns false if tag is to be hidden.
 145          */
 146         public static function tagDescription( $tag, IContextSource $context ) {
 147                 $msg = $context->msg( "tag-$tag" );
 148                 if ( !$msg->exists() ) {
 149                         // No such message, so return the HTML-escaped tag name.
 150                         return htmlspecialchars( $tag );
 151                 }
 152                 if ( $msg->isDisabled() ) {
 153                         // The message exists but is disabled, hide the tag.
 154                         return false;
 155                 }
 156
 157                 // Message exists and isn't disabled, use it.
 158                 return $msg->parse();
 159         }
 160
 161         /**
 162          * Get the message object for the tag's long description.
 163          *
 164          * Checks if message key "mediawiki:tag-$tag-description" exists. If it does not,
 165          * or if message is disabled, returns false. Otherwise, returns the message object
 166          * for the long description.
 167          *
 168          * @param string $tag
 169          * @param IContextSource $context
 170          * @return Message|bool Message object of the tag long description or false if
 171          *  there is no description.
 172          */
 173         public static function tagLongDescriptionMessage( $tag, IContextSource $context ) {
 174                 $msg = $context->msg( "tag-$tag-description" );
 175                 if ( !$msg->exists() ) {
 176                         return false;
 177                 }
 178                 if ( $msg->isDisabled() ) {
 179                         // The message exists but is disabled, hide the description.
 180                         return false;
 181                 }
 182
 183                 // Message exists and isn't disabled, use it.
 184                 return $msg;
 185         }
 186
 187         /**
 188          * Get truncated message for the tag's long description.
 189          *
 190          * @param string $tag Tag name.
 191          * @param int $length Maximum length of truncated message, including ellipsis.
 192          * @param IContextSource $context
 193          *
 194          * @return string Truncated long tag description.
 195          */
 196         public static function truncateTagDescription( $tag, $length, IContextSource $context ) {
 197                 $originalDesc = self::tagLongDescriptionMessage( $tag, $context );
 198                 // If there is no tag description, return empty string
 199                 if ( !$originalDesc ) {
 200                         return '';
 201                 }
 202
 203                 $taglessDesc = Sanitizer::stripAllTags( $originalDesc->parse() );
 204                 $escapedDesc = Sanitizer::escapeHtmlAllowEntities( $taglessDesc );
 205
 206                 return $context->getLanguage()->truncateForVisual( $escapedDesc, $length );
 207         }
 208
 209         /**
 210          * Add tags to a change given its rc_id, rev_id and/or log_id
 211          *
 212          * @param string|string[] $tags Tags to add to the change
 213          * @param int|null $rc_id The rc_id of the change to add the tags to
 214          * @param int|null $rev_id The rev_id of the change to add the tags to
 215          * @param int|null $log_id The log_id of the change to add the tags to
 216          * @param string $params Params to put in the ct_params field of table 'change_tag'
 217          * @param RecentChange|null $rc Recent change, in case the tagging accompanies the action
 218          * (this should normally be the case)
 219          *
 220          * @throws MWException
 221          * @return bool False if no changes are made, otherwise true
 222          */
 223         public static function addTags( $tags, $rc_id = null, $rev_id = null,
 224                 $log_id = null, $params = null, RecentChange $rc = null
 225         ) {
 226                 $result = self::updateTags( $tags, null, $rc_id, $rev_id, $log_id, $params, $rc );
 227                 return (bool)$result[0];
 228         }
 229
 230         /**
 231          * Add and remove tags to/from a change given its rc_id, rev_id and/or log_id,
 232          * without verifying that the tags exist or are valid. If a tag is present in
 233          * both $tagsToAdd and $tagsToRemove, it will be removed.
 234          *
 235          * This function should only be used by extensions to manipulate tags they
 236          * have registered using the ListDefinedTags hook. When dealing with user
 237          * input, call updateTagsWithChecks() instead.
 238          *
 239          * @param string|array|null $tagsToAdd Tags to add to the change
 240          * @param string|array|null $tagsToRemove Tags to remove from the change
 241          * @param int|null &$rc_id The rc_id of the change to add the tags to.
 242          * Pass a variable whose value is null if the rc_id is not relevant or unknown.
 243          * @param int|null &$rev_id The rev_id of the change to add the tags to.
 244          * Pass a variable whose value is null if the rev_id is not relevant or unknown.
 245          * @param int|null &$log_id The log_id of the change to add the tags to.
 246          * Pass a variable whose value is null if the log_id is not relevant or unknown.
 247          * @param string $params Params to put in the ct_params field of table
 248          * 'change_tag' when adding tags
 249          * @param RecentChange|null $rc Recent change being tagged, in case the tagging accompanies
 250          * the action
 251          * @param User|null $user Tagging user, in case the tagging is subsequent to the tagged action
 252          *
 253          * @throws MWException When $rc_id, $rev_id and $log_id are all null
 254          * @return array Index 0 is an array of tags actually added, index 1 is an
 255          * array of tags actually removed, index 2 is an array of tags present on the
 256          * revision or log entry before any changes were made
 257          *
 258          * @since 1.25
 259          */
 260         public static function updateTags( $tagsToAdd, $tagsToRemove, &$rc_id = null,
 261                 &$rev_id = null, &$log_id = null, $params = null, RecentChange $rc = null,
 262                 User $user = null
 263         ) {
 264                 global $wgChangeTagsSchemaMigrationStage;
 265
 266                 $tagsToAdd = array_filter( (array)$tagsToAdd ); // Make sure we're submitting all tags...
 267                 $tagsToRemove = array_filter( (array)$tagsToRemove );
 268
 269                 if ( !$rc_id && !$rev_id && !$log_id ) {
 270                         throw new MWException( 'At least one of: RCID, revision ID, and log ID MUST be ' .
 271                                 'specified when adding or removing a tag from a change!' );
 272                 }
 273
 274                 $dbw = wfGetDB( DB_MASTER );
 275
 276                 // Might as well look for rcids and so on.
 277                 if ( !$rc_id ) {
 278                         // Info might be out of date, somewhat fractionally, on replica DB.
 279                         // LogEntry/LogPage and WikiPage match rev/log/rc timestamps,
 280                         // so use that relation to avoid full table scans.
 281                         if ( $log_id ) {
 282                                 $rc_id = $dbw->selectField(
 283                                         [ 'logging', 'recentchanges' ],
 284                                         'rc_id',
 285                                         [
 286                                                 'log_id' => $log_id,
 287                                                 'rc_timestamp = log_timestamp',
 288                                                 'rc_logid = log_id'
 289                                         ],
 290                                         __METHOD__
 291                                 );
 292                         } elseif ( $rev_id ) {
 293                                 $rc_id = $dbw->selectField(
 294                                         [ 'revision', 'recentchanges' ],
 295                                         'rc_id',
 296                                         [
 297                                                 'rev_id' => $rev_id,
 298                                                 'rc_timestamp = rev_timestamp',
 299                                                 'rc_this_oldid = rev_id'
 300                                         ],
 301                                         __METHOD__
 302                                 );
 303                         }
 304                 } elseif ( !$log_id && !$rev_id ) {
 305                         // Info might be out of date, somewhat fractionally, on replica DB.
 306                         $log_id = $dbw->selectField(
 307                                 'recentchanges',
 308                                 'rc_logid',
 309                                 [ 'rc_id' => $rc_id ],
 310                                 __METHOD__
 311                         );
 312                         $rev_id = $dbw->selectField(
 313                                 'recentchanges',
 314                                 'rc_this_oldid',
 315                                 [ 'rc_id' => $rc_id ],
 316                                 __METHOD__
 317                         );
 318                 }
 319
 320                 if ( $log_id && !$rev_id ) {
 321                         $rev_id = $dbw->selectField(
 322                                 'log_search',
 323                                 'ls_value',
 324                                 [ 'ls_field' => 'associated_rev_id', 'ls_log_id' => $log_id ],
 325                                 __METHOD__
 326                         );
 327                 } elseif ( !$log_id && $rev_id ) {
 328                         $log_id = $dbw->selectField(
 329                                 'log_search',
 330                                 'ls_log_id',
 331                                 [ 'ls_field' => 'associated_rev_id', 'ls_value' => $rev_id ],
 332                                 __METHOD__
 333                         );
 334                 }
 335
 336                 // update the tag_summary row
 337                 $prevTags = [];
 338                 if ( !self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $rc_id, $rev_id,
 339                         $log_id, $prevTags )
 340                 ) {
 341                         // nothing to do
 342                         return [ [], [], $prevTags ];
 343                 }
 344
 345                 // insert a row into change_tag for each new tag
 346                 if ( count( $tagsToAdd ) ) {
 347                         $changeTagMapping = [];
 348                         if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
 349                                 $changeTagDefStore = MediaWikiServices::getInstance()->getChangeTagDefStore();
 350
 351                                 foreach ( $tagsToAdd as $tag ) {
 352                                         $changeTagMapping[$tag] = $changeTagDefStore->acquireId( $tag );
 353                                 }
 354
 355                                 $dbw->update(
 356                                         'change_tag_def',
 357                                         [ 'ctd_count = ctd_count + 1' ],
 358                                         [ 'ctd_name' => $tagsToAdd ],
 359                                         __METHOD__
 360                                 );
 361                         }
 362
 363                         $tagsRows = [];
 364                         foreach ( $tagsToAdd as $tag ) {
 365                                 // Filter so we don't insert NULLs as zero accidentally.
 366                                 // Keep in mind that $rc_id === null means "I don't care/know about the
 367                                 // rc_id, just delete $tag on this revision/log entry". It doesn't
 368                                 // mean "only delete tags on this revision/log WHERE rc_id IS NULL".
 369                                 $tagsRows[] = array_filter(
 370                                         [
 371                                                 'ct_tag' => $tag,
 372                                                 'ct_rc_id' => $rc_id,
 373                                                 'ct_log_id' => $log_id,
 374                                                 'ct_rev_id' => $rev_id,
 375                                                 'ct_params' => $params,
 376                                                 'ct_tag_id' => $changeTagMapping[$tag] ?? null,
 377                                         ]
 378                                 );
 379
 380                         }
 381
 382                         $dbw->insert( 'change_tag', $tagsRows, __METHOD__, [ 'IGNORE' ] );
 383                 }
 384
 385                 // delete from change_tag
 386                 if ( count( $tagsToRemove ) ) {
 387                         foreach ( $tagsToRemove as $tag ) {
 388                                 $conds = array_filter(
 389                                         [
 390                                                 'ct_tag' => $tag,
 391                                                 'ct_rc_id' => $rc_id,
 392                                                 'ct_log_id' => $log_id,
 393                                                 'ct_rev_id' => $rev_id
 394                                         ]
 395                                 );
 396                                 $dbw->delete( 'change_tag', $conds, __METHOD__ );
 397                                 if ( $dbw->affectedRows() && $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
 398                                         $dbw->update(
 399                                                 'change_tag_def',
 400                                                 [ 'ctd_count = ctd_count - 1' ],
 401                                                 [ 'ctd_name' => $tag ],
 402                                                 __METHOD__
 403                                         );
 404
 405                                         $dbw->delete(
 406                                                 'change_tag_def',
 407                                                 [ 'ctd_name' => $tag, 'ctd_count' => 0, 'ctd_user_defined' => 0 ],
 408                                                 __METHOD__
 409                                         );
 410                                 }
 411                         }
 412                 }
 413
 414                 self::purgeTagUsageCache();
 415
 416                 Hooks::run( 'ChangeTagsAfterUpdateTags', [ $tagsToAdd, $tagsToRemove, $prevTags,
 417                         $rc_id, $rev_id, $log_id, $params, $rc, $user ] );
 418
 419                 return [ $tagsToAdd, $tagsToRemove, $prevTags ];
 420         }
 421
 422         /**
 423          * Adds or removes a given set of tags to/from the relevant row of the
 424          * tag_summary table. Modifies the tagsToAdd and tagsToRemove arrays to
 425          * reflect the tags that were actually added and/or removed.
 426          *
 427          * @param array &$tagsToAdd
 428          * @param array &$tagsToRemove If a tag is present in both $tagsToAdd and
 429          * $tagsToRemove, it will be removed
 430          * @param int|null $rc_id Null if not known or not applicable
 431          * @param int|null $rev_id Null if not known or not applicable
 432          * @param int|null $log_id Null if not known or not applicable
 433          * @param array &$prevTags Optionally outputs a list of the tags that were
 434          * in the tag_summary row to begin with
 435          * @return bool True if any modifications were made, otherwise false
 436          * @since 1.25
 437          */
 438         protected static function updateTagSummaryRow( &$tagsToAdd, &$tagsToRemove,
 439                 $rc_id, $rev_id, $log_id, &$prevTags = []
 440         ) {
 441                 $dbw = wfGetDB( DB_MASTER );
 442
 443                 $tsConds = array_filter( [
 444                         'ts_rc_id' => $rc_id,
 445                         'ts_rev_id' => $rev_id,
 446                         'ts_log_id' => $log_id
 447                 ] );
 448
 449                 // Can't both add and remove a tag at the same time...
 450                 $tagsToAdd = array_diff( $tagsToAdd, $tagsToRemove );
 451
 452                 // Update the summary row.
 453                 // $prevTags can be out of date on replica DBs, especially when addTags is called consecutively,
 454                 // causing loss of tags added recently in tag_summary table.
 455                 $prevTags = $dbw->selectField( 'tag_summary', 'ts_tags', $tsConds, __METHOD__ );
 456                 $prevTags = $prevTags ?: '';
 457                 $prevTags = array_filter( explode( ',', $prevTags ) );
 458
 459                 // add tags
 460                 $tagsToAdd = array_values( array_diff( $tagsToAdd, $prevTags ) );
 461                 $newTags = array_unique( array_merge( $prevTags, $tagsToAdd ) );
 462
 463                 // remove tags
 464                 $tagsToRemove = array_values( array_intersect( $tagsToRemove, $newTags ) );
 465                 $newTags = array_values( array_diff( $newTags, $tagsToRemove ) );
 466
 467                 sort( $prevTags );
 468                 sort( $newTags );
 469                 if ( $prevTags == $newTags ) {
 470                         return false;
 471                 }
 472
 473                 if ( !$newTags ) {
 474                         // No tags left, so delete the row altogether
 475                         $dbw->delete( 'tag_summary', $tsConds, __METHOD__ );
 476                 } else {
 477                         // Specify the non-DEFAULT value columns in the INSERT/REPLACE clause
 478                         $row = array_filter( [ 'ts_tags' => implode( ',', $newTags ) ] + $tsConds );
 479                         // Check the unique keys for conflicts, ignoring any NULL *_id values
 480                         $uniqueKeys = [];
 481                         foreach ( [ 'ts_rev_id', 'ts_rc_id', 'ts_log_id' ] as $uniqueColumn ) {
 482                                 if ( isset( $row[$uniqueColumn] ) ) {
 483                                         $uniqueKeys[] = [ $uniqueColumn ];
 484                                 }
 485                         }
 486
 487                         $dbw->replace( 'tag_summary', $uniqueKeys, $row, __METHOD__ );
 488                 }
 489
 490                 return true;
 491         }
 492
 493         /**
 494          * Helper function to generate a fatal status with a 'not-allowed' type error.
 495          *
 496          * @param string $msgOne Message key to use in the case of one tag
 497          * @param string $msgMulti Message key to use in the case of more than one tag
 498          * @param array $tags Restricted tags (passed as $1 into the message, count of
 499          * $tags passed as $2)
 500          * @return Status
 501          * @since 1.25
 502          */
 503         protected static function restrictedTagError( $msgOne, $msgMulti, $tags ) {
 504                 $lang = RequestContext::getMain()->getLanguage();
 505                 $count = count( $tags );
 506                 return Status::newFatal( ( $count > 1 ) ? $msgMulti : $msgOne,
 507                         $lang->commaList( $tags ), $count );
 508         }
 509
 510         /**
 511          * Is it OK to allow the user to apply all the specified tags at the same time
 512          * as they edit/make the change?
 513          *
 514          * Extensions should not use this function, unless directly handling a user
 515          * request to add a tag to a revision or log entry that the user is making.
 516          *
 517          * @param array $tags Tags that you are interested in applying
 518          * @param User|null $user User whose permission you wish to check, or null to
 519          * check for a generic non-blocked user with the relevant rights
 520          * @return Status
 521          * @since 1.25
 522          */
 523         public static function canAddTagsAccompanyingChange( array $tags, User $user = null ) {
 524                 if ( !is_null( $user ) ) {
 525                         if ( !$user->isAllowed( 'applychangetags' ) ) {
 526                                 return Status::newFatal( 'tags-apply-no-permission' );
 527                         } elseif ( $user->isBlocked() ) {
 528                                 return Status::newFatal( 'tags-apply-blocked', $user->getName() );
 529                         }
 530                 }
 531
 532                 // to be applied, a tag has to be explicitly defined
 533                 $allowedTags = self::listExplicitlyDefinedTags();
 534                 Hooks::run( 'ChangeTagsAllowedAdd', [ &$allowedTags, $tags, $user ] );
 535                 $disallowedTags = array_diff( $tags, $allowedTags );
 536                 if ( $disallowedTags ) {
 537                         return self::restrictedTagError( 'tags-apply-not-allowed-one',
 538                                 'tags-apply-not-allowed-multi', $disallowedTags );
 539                 }
 540
 541                 return Status::newGood();
 542         }
 543
 544         /**
 545          * Adds tags to a given change, checking whether it is allowed first, but
 546          * without adding a log entry. Useful for cases where the tag is being added
 547          * along with the action that generated the change (e.g. tagging an edit as
 548          * it is being made).
 549          *
 550          * Extensions should not use this function, unless directly handling a user
 551          * request to add a particular tag. Normally, extensions should call
 552          * ChangeTags::updateTags() instead.
 553          *
 554          * @param array $tags Tags to apply
 555          * @param int|null $rc_id The rc_id of the change to add the tags to
 556          * @param int|null $rev_id The rev_id of the change to add the tags to
 557          * @param int|null $log_id The log_id of the change to add the tags to
 558          * @param string $params Params to put in the ct_params field of table
 559          * 'change_tag' when adding tags
 560          * @param User $user Who to give credit for the action
 561          * @return Status
 562          * @since 1.25
 563          */
 564         public static function addTagsAccompanyingChangeWithChecks(
 565                 array $tags, $rc_id, $rev_id, $log_id, $params, User $user
 566         ) {
 567                 // are we allowed to do this?
 568                 $result = self::canAddTagsAccompanyingChange( $tags, $user );
 569                 if ( !$result->isOK() ) {
 570                         $result->value = null;
 571                         return $result;
 572                 }
 573
 574                 // do it!
 575                 self::addTags( $tags, $rc_id, $rev_id, $log_id, $params );
 576
 577                 return Status::newGood( true );
 578         }
 579
 580         /**
 581          * Is it OK to allow the user to adds and remove the given tags tags to/from a
 582          * change?
 583          *
 584          * Extensions should not use this function, unless directly handling a user
 585          * request to add or remove tags from an existing revision or log entry.
 586          *
 587          * @param array $tagsToAdd Tags that you are interested in adding
 588          * @param array $tagsToRemove Tags that you are interested in removing
 589          * @param User|null $user User whose permission you wish to check, or null to
 590          * check for a generic non-blocked user with the relevant rights
 591          * @return Status
 592          * @since 1.25
 593          */
 594         public static function canUpdateTags( array $tagsToAdd, array $tagsToRemove,
 595                 User $user = null
 596         ) {
 597                 if ( !is_null( $user ) ) {
 598                         if ( !$user->isAllowed( 'changetags' ) ) {
 599                                 return Status::newFatal( 'tags-update-no-permission' );
 600                         } elseif ( $user->isBlocked() ) {
 601                                 return Status::newFatal( 'tags-update-blocked', $user->getName() );
 602                         }
 603                 }
 604
 605                 if ( $tagsToAdd ) {
 606                         // to be added, a tag has to be explicitly defined
 607                         // @todo Allow extensions to define tags that can be applied by users...
 608                         $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
 609                         $diff = array_diff( $tagsToAdd, $explicitlyDefinedTags );
 610                         if ( $diff ) {
 611                                 return self::restrictedTagError( 'tags-update-add-not-allowed-one',
 612                                         'tags-update-add-not-allowed-multi', $diff );
 613                         }
 614                 }
 615
 616                 if ( $tagsToRemove ) {
 617                         // to be removed, a tag must not be defined by an extension, or equivalently it
 618                         // has to be either explicitly defined or not defined at all
 619                         // (assuming no edge case of a tag both explicitly-defined and extension-defined)
 620                         $softwareDefinedTags = self::listSoftwareDefinedTags();
 621                         $intersect = array_intersect( $tagsToRemove, $softwareDefinedTags );
 622                         if ( $intersect ) {
 623                                 return self::restrictedTagError( 'tags-update-remove-not-allowed-one',
 624                                         'tags-update-remove-not-allowed-multi', $intersect );
 625                         }
 626                 }
 627
 628                 return Status::newGood();
 629         }
 630
 631         /**
 632          * Adds and/or removes tags to/from a given change, checking whether it is
 633          * allowed first, and adding a log entry afterwards.
 634          *
 635          * Includes a call to ChangeTags::canUpdateTags(), so your code doesn't need
 636          * to do that. However, it doesn't check whether the *_id parameters are a
 637          * valid combination. That is up to you to enforce. See ApiTag::execute() for
 638          * an example.
 639          *
 640          * Extensions should generally avoid this function. Call
 641          * ChangeTags::updateTags() instead, unless directly handling a user request
 642          * to add or remove tags from an existing revision or log entry.
 643          *
 644          * @param array|null $tagsToAdd If none, pass array() or null
 645          * @param array|null $tagsToRemove If none, pass array() or null
 646          * @param int|null $rc_id The rc_id of the change to add the tags to
 647          * @param int|null $rev_id The rev_id of the change to add the tags to
 648          * @param int|null $log_id The log_id of the change to add the tags to
 649          * @param string $params Params to put in the ct_params field of table
 650          * 'change_tag' when adding tags
 651          * @param string $reason Comment for the log
 652          * @param User $user Who to give credit for the action
 653          * @return Status If successful, the value of this Status object will be an
 654          * object (stdClass) with the following fields:
 655          *  - logId: the ID of the added log entry, or null if no log entry was added
 656          *    (i.e. no operation was performed)
 657          *  - addedTags: an array containing the tags that were actually added
 658          *  - removedTags: an array containing the tags that were actually removed
 659          * @since 1.25
 660          */
 661         public static function updateTagsWithChecks( $tagsToAdd, $tagsToRemove,
 662                 $rc_id, $rev_id, $log_id, $params, $reason, User $user
 663         ) {
 664                 if ( is_null( $tagsToAdd ) ) {
 665                         $tagsToAdd = [];
 666                 }
 667                 if ( is_null( $tagsToRemove ) ) {
 668                         $tagsToRemove = [];
 669                 }
 670                 if ( !$tagsToAdd && !$tagsToRemove ) {
 671                         // no-op, don't bother
 672                         return Status::newGood( (object)[
 673                                 'logId' => null,
 674                                 'addedTags' => [],
 675                                 'removedTags' => [],
 676                         ] );
 677                 }
 678
 679                 // are we allowed to do this?
 680                 $result = self::canUpdateTags( $tagsToAdd, $tagsToRemove, $user );
 681                 if ( !$result->isOK() ) {
 682                         $result->value = null;
 683                         return $result;
 684                 }
 685
 686                 // basic rate limiting
 687                 if ( $user->pingLimiter( 'changetag' ) ) {
 688                         return Status::newFatal( 'actionthrottledtext' );
 689                 }
 690
 691                 // do it!
 692                 list( $tagsAdded, $tagsRemoved, $initialTags ) = self::updateTags( $tagsToAdd,
 693                         $tagsToRemove, $rc_id, $rev_id, $log_id, $params, null, $user );
 694                 if ( !$tagsAdded && !$tagsRemoved ) {
 695                         // no-op, don't log it
 696                         return Status::newGood( (object)[
 697                                 'logId' => null,
 698                                 'addedTags' => [],
 699                                 'removedTags' => [],
 700                         ] );
 701                 }
 702
 703                 // log it
 704                 $logEntry = new ManualLogEntry( 'tag', 'update' );
 705                 $logEntry->setPerformer( $user );
 706                 $logEntry->setComment( $reason );
 707
 708                 // find the appropriate target page
 709                 if ( $rev_id ) {
 710                         $rev = Revision::newFromId( $rev_id );
 711                         if ( $rev ) {
 712                                 $logEntry->setTarget( $rev->getTitle() );
 713                         }
 714                 } elseif ( $log_id ) {
 715                         // This function is from revision deletion logic and has nothing to do with
 716                         // change tags, but it appears to be the only other place in core where we
 717                         // perform logged actions on log items.
 718                         $logEntry->setTarget( RevDelLogList::suggestTarget( null, [ $log_id ] ) );
 719                 }
 720
 721                 if ( !$logEntry->getTarget() ) {
 722                         // target is required, so we have to set something
 723                         $logEntry->setTarget( SpecialPage::getTitleFor( 'Tags' ) );
 724                 }
 725
 726                 $logParams = [
 727                         '4::revid' => $rev_id,
 728                         '5::logid' => $log_id,
 729                         '6:list:tagsAdded' => $tagsAdded,
 730                         '7:number:tagsAddedCount' => count( $tagsAdded ),
 731                         '8:list:tagsRemoved' => $tagsRemoved,
 732                         '9:number:tagsRemovedCount' => count( $tagsRemoved ),
 733                         'initialTags' => $initialTags,
 734                 ];
 735                 $logEntry->setParameters( $logParams );
 736                 $logEntry->setRelations( [ 'Tag' => array_merge( $tagsAdded, $tagsRemoved ) ] );
 737
 738                 $dbw = wfGetDB( DB_MASTER );
 739                 $logId = $logEntry->insert( $dbw );
 740                 // Only send this to UDP, not RC, similar to patrol events
 741                 $logEntry->publish( $logId, 'udp' );
 742
 743                 return Status::newGood( (object)[
 744                         'logId' => $logId,
 745                         'addedTags' => $tagsAdded,
 746                         'removedTags' => $tagsRemoved,
 747                 ] );
 748         }
 749
 750         /**
 751          * Applies all tags-related changes to a query.
 752          * Handles selecting tags, and filtering.
 753          * Needs $tables to be set up properly, so we can figure out which join conditions to use.
 754          *
 755          * WARNING: If $filter_tag contains more than one tag, this function will add DISTINCT,
 756          * which may cause performance problems for your query unless you put the ID field of your
 757          * table at the end of the ORDER BY, and set a GROUP BY equal to the ORDER BY. For example,
 758          * if you had ORDER BY foo_timestamp DESC, you will now need GROUP BY foo_timestamp, foo_id
 759          * ORDER BY foo_timestamp DESC, foo_id DESC.
 760          *
 761          * @param string|array &$tables Table names, see Database::select
 762          * @param string|array &$fields Fields used in query, see Database::select
 763          * @param string|array &$conds Conditions used in query, see Database::select
 764          * @param array &$join_conds Join conditions, see Database::select
 765          * @param string|array &$options Options, see Database::select
 766          * @param string|array $filter_tag Tag(s) to select on
 767          *
 768          * @throws MWException When unable to determine appropriate JOIN condition for tagging
 769          */
 770         public static function modifyDisplayQuery( &$tables, &$fields, &$conds,
 771                 &$join_conds, &$options, $filter_tag = ''
 772         ) {
 773                 global $wgUseTagFilter;
 774
 775                 // Normalize to arrays
 776                 $tables = (array)$tables;
 777                 $fields = (array)$fields;
 778                 $conds = (array)$conds;
 779                 $options = (array)$options;
 780
 781                 // Figure out which ID field to use
 782                 if ( in_array( 'recentchanges', $tables ) ) {
 783                         $join_cond = 'ct_rc_id=rc_id';
 784                 } elseif ( in_array( 'logging', $tables ) ) {
 785                         $join_cond = 'ct_log_id=log_id';
 786                 } elseif ( in_array( 'revision', $tables ) ) {
 787                         $join_cond = 'ct_rev_id=rev_id';
 788                 } elseif ( in_array( 'archive', $tables ) ) {
 789                         $join_cond = 'ct_rev_id=ar_rev_id';
 790                 } else {
 791                         throw new MWException( 'Unable to determine appropriate JOIN condition for tagging.' );
 792                 }
 793
 794                 $fields['ts_tags'] = wfGetDB( DB_REPLICA )->buildGroupConcatField(
 795                         ',', 'change_tag', 'ct_tag', $join_cond
 796                 );
 797
 798                 if ( $wgUseTagFilter && $filter_tag ) {
 799                         // Somebody wants to filter on a tag.
 800                         // Add an INNER JOIN on change_tag
 801
 802                         $tables[] = 'change_tag';
 803                         $join_conds['change_tag'] = [ 'INNER JOIN', $join_cond ];
 804                         $conds['ct_tag'] = $filter_tag;
 805                         if (
 806                                 is_array( $filter_tag ) && count( $filter_tag ) > 1 &&
 807                                 !in_array( 'DISTINCT', $options )
 808                         ) {
 809                                 $options[] = 'DISTINCT';
 810                         }
 811                 }
 812         }
 813
 814         /**
 815          * Build a text box to select a change tag
 816          *
 817          * @param string $selected Tag to select by default
 818          * @param bool $ooui Use an OOUI TextInputWidget as selector instead of a non-OOUI input field
 819          *        You need to call OutputPage::enableOOUI() yourself.
 820          * @param IContextSource|null $context
 821          * @note Even though it takes null as a valid argument, an IContextSource is preferred
 822          *       in a new code, as the null value can change in the future
 823          * @return array an array of (label, selector)
 824          */
 825         public static function buildTagFilterSelector(
 826                 $selected = '', $ooui = false, IContextSource $context = null
 827         ) {
 828                 if ( !$context ) {
 829                         $context = RequestContext::getMain();
 830                 }
 831
 832                 $config = $context->getConfig();
 833                 if ( !$config->get( 'UseTagFilter' ) || !count( self::listDefinedTags() ) ) {
 834                         return [];
 835                 }
 836
 837                 $data = [
 838                         Html::rawElement(
 839                                 'label',
 840                                 [ 'for' => 'tagfilter' ],
 841                                 $context->msg( 'tag-filter' )->parse()
 842                         )
 843                 ];
 844
 845                 if ( $ooui ) {
 846                         $data[] = new OOUI\TextInputWidget( [
 847                                 'id' => 'tagfilter',
 848                                 'name' => 'tagfilter',
 849                                 'value' => $selected,
 850                                 'classes' => 'mw-tagfilter-input',
 851                         ] );
 852                 } else {
 853                         $data[] = Xml::input(
 854                                 'tagfilter',
 855                                 20,
 856                                 $selected,
 857                                 [ 'class' => 'mw-tagfilter-input mw-ui-input mw-ui-input-inline', 'id' => 'tagfilter' ]
 858                         );
 859                 }
 860
 861                 return $data;
 862         }
 863
 864         /**
 865          * Defines a tag in the valid_tag table and/or update ctd_user_defined field in change_tag_def,
 866          * without checking that the tag name is valid.
 867          * Extensions should NOT use this function; they can use the ListDefinedTags
 868          * hook instead.
 869          *
 870          * @param string $tag Tag to create
 871          * @since 1.25
 872          */
 873         public static function defineTag( $tag ) {
 874                 global $wgChangeTagsSchemaMigrationStage;
 875
 876                 $dbw = wfGetDB( DB_MASTER );
 877                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
 878                         $tagDef = [
 879                                 'ctd_name' => $tag,
 880                                 'ctd_user_defined' => 1,
 881                                 'ctd_count' => 0
 882                         ];
 883                         $dbw->upsert(
 884                                 'change_tag_def',
 885                                 $tagDef,
 886                                 [ 'ctd_name' ],
 887                                 [ 'ctd_user_defined' => 1 ],
 888                                 __METHOD__
 889                         );
 890                 }
 891
 892                 $dbw->replace(
 893                         'valid_tag',
 894                         [ 'vt_tag' ],
 895                         [ 'vt_tag' => $tag ],
 896                         __METHOD__
 897                 );
 898
 899                 // clear the memcache of defined tags
 900                 self::purgeTagCacheAll();
 901         }
 902
 903         /**
 904          * Removes a tag from the valid_tag table and/or update ctd_user_defined field in change_tag_def.
 905          * The tag may remain in use by extensions, and may still show up as 'defined'
 906          * if an extension is setting it from the ListDefinedTags hook.
 907          *
 908          * @param string $tag Tag to remove
 909          * @since 1.25
 910          */
 911         public static function undefineTag( $tag ) {
 912                 global $wgChangeTagsSchemaMigrationStage;
 913
 914                 $dbw = wfGetDB( DB_MASTER );
 915
 916                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
 917                         $dbw->update(
 918                                 'change_tag_def',
 919                                 [ 'ctd_name' => $tag ],
 920                                 [ 'ctd_user_defined' => 0 ],
 921                                 __METHOD__
 922                         );
 923
 924                         $dbw->delete(
 925                                 'change_tag_def',
 926                                 [ 'ctd_name' => $tag, 'ctd_count' => 0 ],
 927                                 __METHOD__
 928                         );
 929                 }
 930
 931                 $dbw->delete( 'valid_tag', [ 'vt_tag' => $tag ], __METHOD__ );
 932
 933                 // clear the memcache of defined tags
 934                 self::purgeTagCacheAll();
 935         }
 936
 937         /**
 938          * Writes a tag action into the tag management log.
 939          *
 940          * @param string $action
 941          * @param string $tag
 942          * @param string $reason
 943          * @param User $user Who to attribute the action to
 944          * @param int $tagCount For deletion only, how many usages the tag had before
 945          * it was deleted.
 946          * @param array $logEntryTags Change tags to apply to the entry
 947          * that will be created in the tag management log
 948          * @return int ID of the inserted log entry
 949          * @since 1.25
 950          */
 951         protected static function logTagManagementAction( $action, $tag, $reason,
 952                 User $user, $tagCount = null, array $logEntryTags = []
 953         ) {
 954                 $dbw = wfGetDB( DB_MASTER );
 955
 956                 $logEntry = new ManualLogEntry( 'managetags', $action );
 957                 $logEntry->setPerformer( $user );
 958                 // target page is not relevant, but it has to be set, so we just put in
 959                 // the title of Special:Tags
 960                 $logEntry->setTarget( Title::newFromText( 'Special:Tags' ) );
 961                 $logEntry->setComment( $reason );
 962
 963                 $params = [ '4::tag' => $tag ];
 964                 if ( !is_null( $tagCount ) ) {
 965                         $params['5:number:count'] = $tagCount;
 966                 }
 967                 $logEntry->setParameters( $params );
 968                 $logEntry->setRelations( [ 'Tag' => $tag ] );
 969                 $logEntry->setTags( $logEntryTags );
 970
 971                 $logId = $logEntry->insert( $dbw );
 972                 $logEntry->publish( $logId );
 973                 return $logId;
 974         }
 975
 976         /**
 977          * Is it OK to allow the user to activate this tag?
 978          *
 979          * @param string $tag Tag that you are interested in activating
 980          * @param User|null $user User whose permission you wish to check, or null if
 981          * you don't care (e.g. maintenance scripts)
 982          * @return Status
 983          * @since 1.25
 984          */
 985         public static function canActivateTag( $tag, User $user = null ) {
 986                 if ( !is_null( $user ) ) {
 987                         if ( !$user->isAllowed( 'managechangetags' ) ) {
 988                                 return Status::newFatal( 'tags-manage-no-permission' );
 989                         } elseif ( $user->isBlocked() ) {
 990                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
 991                         }
 992                 }
 993
 994                 // defined tags cannot be activated (a defined tag is either extension-
 995                 // defined, in which case the extension chooses whether or not to active it;
 996                 // or user-defined, in which case it is considered active)
 997                 $definedTags = self::listDefinedTags();
 998                 if ( in_array( $tag, $definedTags ) ) {
 999                         return Status::newFatal( 'tags-activate-not-allowed', $tag );
1000                 }
1001
1002                 // non-existing tags cannot be activated
1003                 $tagUsage = self::tagUsageStatistics();
1004                 if ( !isset( $tagUsage[$tag] ) ) { // we already know the tag is undefined
1005                         return Status::newFatal( 'tags-activate-not-found', $tag );
1006                 }
1007
1008                 return Status::newGood();
1009         }
1010
1011         /**
1012          * Activates a tag, checking whether it is allowed first, and adding a log
1013          * entry afterwards.
1014          *
1015          * Includes a call to ChangeTag::canActivateTag(), so your code doesn't need
1016          * to do that.
1017          *
1018          * @param string $tag
1019          * @param string $reason
1020          * @param User $user Who to give credit for the action
1021          * @param bool $ignoreWarnings Can be used for API interaction, default false
1022          * @param array $logEntryTags Change tags to apply to the entry
1023          * that will be created in the tag management log
1024          * @return Status If successful, the Status contains the ID of the added log
1025          * entry as its value
1026          * @since 1.25
1027          */
1028         public static function activateTagWithChecks( $tag, $reason, User $user,
1029                 $ignoreWarnings = false, array $logEntryTags = []
1030         ) {
1031                 // are we allowed to do this?
1032                 $result = self::canActivateTag( $tag, $user );
1033                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1034                         $result->value = null;
1035                         return $result;
1036                 }
1037
1038                 // do it!
1039                 self::defineTag( $tag );
1040
1041                 // log it
1042                 $logId = self::logTagManagementAction( 'activate', $tag, $reason, $user,
1043                         null, $logEntryTags );
1044
1045                 return Status::newGood( $logId );
1046         }
1047
1048         /**
1049          * Is it OK to allow the user to deactivate this tag?
1050          *
1051          * @param string $tag Tag that you are interested in deactivating
1052          * @param User|null $user User whose permission you wish to check, or null if
1053          * you don't care (e.g. maintenance scripts)
1054          * @return Status
1055          * @since 1.25
1056          */
1057         public static function canDeactivateTag( $tag, User $user = null ) {
1058                 if ( !is_null( $user ) ) {
1059                         if ( !$user->isAllowed( 'managechangetags' ) ) {
1060                                 return Status::newFatal( 'tags-manage-no-permission' );
1061                         } elseif ( $user->isBlocked() ) {
1062                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1063                         }
1064                 }
1065
1066                 // only explicitly-defined tags can be deactivated
1067                 $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
1068                 if ( !in_array( $tag, $explicitlyDefinedTags ) ) {
1069                         return Status::newFatal( 'tags-deactivate-not-allowed', $tag );
1070                 }
1071                 return Status::newGood();
1072         }
1073
1074         /**
1075          * Deactivates a tag, checking whether it is allowed first, and adding a log
1076          * entry afterwards.
1077          *
1078          * Includes a call to ChangeTag::canDeactivateTag(), so your code doesn't need
1079          * to do that.
1080          *
1081          * @param string $tag
1082          * @param string $reason
1083          * @param User $user Who to give credit for the action
1084          * @param bool $ignoreWarnings Can be used for API interaction, default false
1085          * @param array $logEntryTags Change tags to apply to the entry
1086          * that will be created in the tag management log
1087          * @return Status If successful, the Status contains the ID of the added log
1088          * entry as its value
1089          * @since 1.25
1090          */
1091         public static function deactivateTagWithChecks( $tag, $reason, User $user,
1092                 $ignoreWarnings = false, array $logEntryTags = []
1093         ) {
1094                 // are we allowed to do this?
1095                 $result = self::canDeactivateTag( $tag, $user );
1096                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1097                         $result->value = null;
1098                         return $result;
1099                 }
1100
1101                 // do it!
1102                 self::undefineTag( $tag );
1103
1104                 // log it
1105                 $logId = self::logTagManagementAction( 'deactivate', $tag, $reason, $user,
1106                         null, $logEntryTags );
1107
1108                 return Status::newGood( $logId );
1109         }
1110
1111         /**
1112          * Is the tag name valid?
1113          *
1114          * @param string $tag Tag that you are interested in creating
1115          * @return Status
1116          * @since 1.30
1117          */
1118         public static function isTagNameValid( $tag ) {
1119                 // no empty tags
1120                 if ( $tag === '' ) {
1121                         return Status::newFatal( 'tags-create-no-name' );
1122                 }
1123
1124                 // tags cannot contain commas (used as a delimiter in tag_summary table),
1125                 // pipe (used as a delimiter between multiple tags in
1126                 // SpecialRecentchanges and friends), or slashes (would break tag description messages in
1127                 // MediaWiki namespace)
1128                 if ( strpos( $tag, ',' ) !== false || strpos( $tag, '|' ) !== false
1129                         || strpos( $tag, '/' ) !== false ) {
1130                         return Status::newFatal( 'tags-create-invalid-chars' );
1131                 }
1132
1133                 // could the MediaWiki namespace description messages be created?
1134                 $title = Title::makeTitleSafe( NS_MEDIAWIKI, "Tag-$tag-description" );
1135                 if ( is_null( $title ) ) {
1136                         return Status::newFatal( 'tags-create-invalid-title-chars' );
1137                 }
1138
1139                 return Status::newGood();
1140         }
1141
1142         /**
1143          * Is it OK to allow the user to create this tag?
1144          *
1145          * Extensions should NOT use this function. In most cases, a tag can be
1146          * defined using the ListDefinedTags hook without any checking.
1147          *
1148          * @param string $tag Tag that you are interested in creating
1149          * @param User|null $user User whose permission you wish to check, or null if
1150          * you don't care (e.g. maintenance scripts)
1151          * @return Status
1152          * @since 1.25
1153          */
1154         public static function canCreateTag( $tag, User $user = null ) {
1155                 if ( !is_null( $user ) ) {
1156                         if ( !$user->isAllowed( 'managechangetags' ) ) {
1157                                 return Status::newFatal( 'tags-manage-no-permission' );
1158                         } elseif ( $user->isBlocked() ) {
1159                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1160                         }
1161                 }
1162
1163                 $status = self::isTagNameValid( $tag );
1164                 if ( !$status->isGood() ) {
1165                         return $status;
1166                 }
1167
1168                 // does the tag already exist?
1169                 $tagUsage = self::tagUsageStatistics();
1170                 if ( isset( $tagUsage[$tag] ) || in_array( $tag, self::listDefinedTags() ) ) {
1171                         return Status::newFatal( 'tags-create-already-exists', $tag );
1172                 }
1173
1174                 // check with hooks
1175                 $canCreateResult = Status::newGood();
1176                 Hooks::run( 'ChangeTagCanCreate', [ $tag, $user, &$canCreateResult ] );
1177                 return $canCreateResult;
1178         }
1179
1180         /**
1181          * Creates a tag by adding a row to the `valid_tag` table.
1182          * and/or add it to `change_tag_def` table.
1183          *
1184          * Extensions should NOT use this function; they can use the ListDefinedTags
1185          * hook instead.
1186          *
1187          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
1188          * do that.
1189          *
1190          * @param string $tag
1191          * @param string $reason
1192          * @param User $user Who to give credit for the action
1193          * @param bool $ignoreWarnings Can be used for API interaction, default false
1194          * @param array $logEntryTags Change tags to apply to the entry
1195          * that will be created in the tag management log
1196          * @return Status If successful, the Status contains the ID of the added log
1197          * entry as its value
1198          * @since 1.25
1199          */
1200         public static function createTagWithChecks( $tag, $reason, User $user,
1201                 $ignoreWarnings = false, array $logEntryTags = []
1202         ) {
1203                 // are we allowed to do this?
1204                 $result = self::canCreateTag( $tag, $user );
1205                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1206                         $result->value = null;
1207                         return $result;
1208                 }
1209
1210                 // do it!
1211                 self::defineTag( $tag );
1212
1213                 // log it
1214                 $logId = self::logTagManagementAction( 'create', $tag, $reason, $user,
1215                         null, $logEntryTags );
1216
1217                 return Status::newGood( $logId );
1218         }
1219
1220         /**
1221          * Permanently removes all traces of a tag from the DB. Good for removing
1222          * misspelt or temporary tags.
1223          *
1224          * This function should be directly called by maintenance scripts only, never
1225          * by user-facing code. See deleteTagWithChecks() for functionality that can
1226          * safely be exposed to users.
1227          *
1228          * @param string $tag Tag to remove
1229          * @return Status The returned status will be good unless a hook changed it
1230          * @since 1.25
1231          */
1232         public static function deleteTagEverywhere( $tag ) {
1233                 global $wgChangeTagsSchemaMigrationStage;
1234                 $dbw = wfGetDB( DB_MASTER );
1235                 $dbw->startAtomic( __METHOD__ );
1236
1237                 // delete from valid_tag and/or set ctd_user_defined = 0
1238                 self::undefineTag( $tag );
1239
1240                 // find out which revisions use this tag, so we can delete from tag_summary
1241                 $result = $dbw->select( 'change_tag',
1242                         [ 'ct_rc_id', 'ct_log_id', 'ct_rev_id', 'ct_tag' ],
1243                         [ 'ct_tag' => $tag ],
1244                         __METHOD__ );
1245                 foreach ( $result as $row ) {
1246                         // remove the tag from the relevant row of tag_summary
1247                         $tagsToAdd = [];
1248                         $tagsToRemove = [ $tag ];
1249                         self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $row->ct_rc_id,
1250                                 $row->ct_rev_id, $row->ct_log_id );
1251                 }
1252
1253                 // delete from change_tag
1254                 $dbw->delete( 'change_tag', [ 'ct_tag' => $tag ], __METHOD__ );
1255
1256                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
1257                         $dbw->delete( 'change_tag_def', [ 'ctd_name' => $tag ], __METHOD__ );
1258                 }
1259
1260                 $dbw->endAtomic( __METHOD__ );
1261
1262                 // give extensions a chance
1263                 $status = Status::newGood();
1264                 Hooks::run( 'ChangeTagAfterDelete', [ $tag, &$status ] );
1265                 // let's not allow error results, as the actual tag deletion succeeded
1266                 if ( !$status->isOK() ) {
1267                         wfDebug( 'ChangeTagAfterDelete error condition downgraded to warning' );
1268                         $status->setOK( true );
1269                 }
1270
1271                 // clear the memcache of defined tags
1272                 self::purgeTagCacheAll();
1273
1274                 return $status;
1275         }
1276
1277         /**
1278          * Is it OK to allow the user to delete this tag?
1279          *
1280          * @param string $tag Tag that you are interested in deleting
1281          * @param User|null $user User whose permission you wish to check, or null if
1282          * you don't care (e.g. maintenance scripts)
1283          * @return Status
1284          * @since 1.25
1285          */
1286         public static function canDeleteTag( $tag, User $user = null ) {
1287                 $tagUsage = self::tagUsageStatistics();
1288
1289                 if ( !is_null( $user ) ) {
1290                         if ( !$user->isAllowed( 'deletechangetags' ) ) {
1291                                 return Status::newFatal( 'tags-delete-no-permission' );
1292                         } elseif ( $user->isBlocked() ) {
1293                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1294                         }
1295                 }
1296
1297                 if ( !isset( $tagUsage[$tag] ) && !in_array( $tag, self::listDefinedTags() ) ) {
1298                         return Status::newFatal( 'tags-delete-not-found', $tag );
1299                 }
1300
1301                 if ( isset( $tagUsage[$tag] ) && $tagUsage[$tag] > self::MAX_DELETE_USES ) {
1302                         return Status::newFatal( 'tags-delete-too-many-uses', $tag, self::MAX_DELETE_USES );
1303                 }
1304
1305                 $softwareDefined = self::listSoftwareDefinedTags();
1306                 if ( in_array( $tag, $softwareDefined ) ) {
1307                         // extension-defined tags can't be deleted unless the extension
1308                         // specifically allows it
1309                         $status = Status::newFatal( 'tags-delete-not-allowed' );
1310                 } else {
1311                         // user-defined tags are deletable unless otherwise specified
1312                         $status = Status::newGood();
1313                 }
1314
1315                 Hooks::run( 'ChangeTagCanDelete', [ $tag, $user, &$status ] );
1316                 return $status;
1317         }
1318
1319         /**
1320          * Deletes a tag, checking whether it is allowed first, and adding a log entry
1321          * afterwards.
1322          *
1323          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
1324          * do that.
1325          *
1326          * @param string $tag
1327          * @param string $reason
1328          * @param User $user Who to give credit for the action
1329          * @param bool $ignoreWarnings Can be used for API interaction, default false
1330          * @param array $logEntryTags Change tags to apply to the entry
1331          * that will be created in the tag management log
1332          * @return Status If successful, the Status contains the ID of the added log
1333          * entry as its value
1334          * @since 1.25
1335          */
1336         public static function deleteTagWithChecks( $tag, $reason, User $user,
1337                 $ignoreWarnings = false, array $logEntryTags = []
1338         ) {
1339                 // are we allowed to do this?
1340                 $result = self::canDeleteTag( $tag, $user );
1341                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1342                         $result->value = null;
1343                         return $result;
1344                 }
1345
1346                 // store the tag usage statistics
1347                 $tagUsage = self::tagUsageStatistics();
1348                 $hitcount = $tagUsage[$tag] ?? 0;
1349
1350                 // do it!
1351                 $deleteResult = self::deleteTagEverywhere( $tag );
1352                 if ( !$deleteResult->isOK() ) {
1353                         return $deleteResult;
1354                 }
1355
1356                 // log it
1357                 $logId = self::logTagManagementAction( 'delete', $tag, $reason, $user,
1358                         $hitcount, $logEntryTags );
1359
1360                 $deleteResult->value = $logId;
1361                 return $deleteResult;
1362         }
1363
1364         /**
1365          * Lists those tags which core or extensions report as being "active".
1366          *
1367          * @return array
1368          * @since 1.25
1369          */
1370         public static function listSoftwareActivatedTags() {
1371                 // core active tags
1372                 $tags = self::getSoftwareTags();
1373                 if ( !Hooks::isRegistered( 'ChangeTagsListActive' ) ) {
1374                         return $tags;
1375                 }
1376                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1377                 return $cache->getWithSetCallback(
1378                         $cache->makeKey( 'active-tags' ),
1379                         WANObjectCache::TTL_MINUTE * 5,
1380                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1381                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1382
1383                                 // Ask extensions which tags they consider active
1384                                 Hooks::run( 'ChangeTagsListActive', [ &$tags ] );
1385                                 return $tags;
1386                         },
1387                         [
1388                                 'checkKeys' => [ $cache->makeKey( 'active-tags' ) ],
1389                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1390                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1391                         ]
1392                 );
1393         }
1394
1395         /**
1396          * Basically lists defined tags which count even if they aren't applied to anything.
1397          * It returns a union of the results of listExplicitlyDefinedTags()
1398          *
1399          * @return string[] Array of strings: tags
1400          */
1401         public static function listDefinedTags() {
1402                 $tags1 = self::listExplicitlyDefinedTags();
1403                 $tags2 = self::listSoftwareDefinedTags();
1404                 return array_values( array_unique( array_merge( $tags1, $tags2 ) ) );
1405         }
1406
1407         /**
1408          * Lists tags explicitly defined in the `valid_tag` table of the database.
1409          * Tags in table 'change_tag' which are not in table 'valid_tag' are not
1410          * included.
1411          *
1412          * Tries memcached first.
1413          *
1414          * @return string[] Array of strings: tags
1415          * @since 1.25
1416          */
1417         public static function listExplicitlyDefinedTags() {
1418                 $fname = __METHOD__;
1419
1420                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1421                 return $cache->getWithSetCallback(
1422                         $cache->makeKey( 'valid-tags-db' ),
1423                         WANObjectCache::TTL_MINUTE * 5,
1424                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1425                                 $dbr = wfGetDB( DB_REPLICA );
1426
1427                                 $setOpts += Database::getCacheSetOptions( $dbr );
1428
1429                                 $tags = $dbr->selectFieldValues( 'valid_tag', 'vt_tag', [], $fname );
1430
1431                                 return array_filter( array_unique( $tags ) );
1432                         },
1433                         [
1434                                 'checkKeys' => [ $cache->makeKey( 'valid-tags-db' ) ],
1435                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1436                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1437                         ]
1438                 );
1439         }
1440
1441         /**
1442          * Lists tags defined by core or extensions using the ListDefinedTags hook.
1443          * Extensions need only define those tags they deem to be in active use.
1444          *
1445          * Tries memcached first.
1446          *
1447          * @return string[] Array of strings: tags
1448          * @since 1.25
1449          */
1450         public static function listSoftwareDefinedTags() {
1451                 // core defined tags
1452                 $tags = self::getSoftwareTags( true );
1453                 if ( !Hooks::isRegistered( 'ListDefinedTags' ) ) {
1454                         return $tags;
1455                 }
1456                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1457                 return $cache->getWithSetCallback(
1458                         $cache->makeKey( 'valid-tags-hook' ),
1459                         WANObjectCache::TTL_MINUTE * 5,
1460                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1461                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1462
1463                                 Hooks::run( 'ListDefinedTags', [ &$tags ] );
1464                                 return array_filter( array_unique( $tags ) );
1465                         },
1466                         [
1467                                 'checkKeys' => [ $cache->makeKey( 'valid-tags-hook' ) ],
1468                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1469                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1470                         ]
1471                 );
1472         }
1473
1474         /**
1475          * Invalidates the short-term cache of defined tags used by the
1476          * list*DefinedTags functions, as well as the tag statistics cache.
1477          * @since 1.25
1478          */
1479         public static function purgeTagCacheAll() {
1480                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1481
1482                 $cache->touchCheckKey( $cache->makeKey( 'active-tags' ) );
1483                 $cache->touchCheckKey( $cache->makeKey( 'valid-tags-db' ) );
1484                 $cache->touchCheckKey( $cache->makeKey( 'valid-tags-hook' ) );
1485
1486                 self::purgeTagUsageCache();
1487         }
1488
1489         /**
1490          * Invalidates the tag statistics cache only.
1491          * @since 1.25
1492          */
1493         public static function purgeTagUsageCache() {
1494                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1495
1496                 $cache->touchCheckKey( $cache->makeKey( 'change-tag-statistics' ) );
1497         }
1498
1499         /**
1500          * Returns a map of any tags used on the wiki to number of edits
1501          * tagged with them, ordered descending by the hitcount.
1502          * This does not include tags defined somewhere that have never been applied.
1503          *
1504          * Keeps a short-term cache in memory, so calling this multiple times in the
1505          * same request should be fine.
1506          *
1507          * @return array Array of string => int
1508          */
1509         public static function tagUsageStatistics() {
1510                 $fname = __METHOD__;
1511                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1512                 return $cache->getWithSetCallback(
1513                         $cache->makeKey( 'change-tag-statistics' ),
1514                         WANObjectCache::TTL_MINUTE * 5,
1515                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1516                                 $dbr = wfGetDB( DB_REPLICA, 'vslow' );
1517
1518                                 $setOpts += Database::getCacheSetOptions( $dbr );
1519
1520                                 $res = $dbr->select(
1521                                         'change_tag',
1522                                         [ 'ct_tag', 'hitcount' => 'count(*)' ],
1523                                         [],
1524                                         $fname,
1525                                         [ 'GROUP BY' => 'ct_tag', 'ORDER BY' => 'hitcount DESC' ]
1526                                 );
1527
1528                                 $out = [];
1529                                 foreach ( $res as $row ) {
1530                                         $out[$row->ct_tag] = $row->hitcount;
1531                                 }
1532
1533                                 return $out;
1534                         },
1535                         [
1536                                 'checkKeys' => [ $cache->makeKey( 'change-tag-statistics' ) ],
1537                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1538                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1539                         ]
1540                 );
1541         }
1542
1543         /**
1544          * Indicate whether change tag editing UI is relevant
1545          *
1546          * Returns true if the user has the necessary right and there are any
1547          * editable tags defined.
1548          *
1549          * This intentionally doesn't check "any addable || any deletable", because
1550          * it seems like it would be more confusing than useful if the checkboxes
1551          * suddenly showed up because some abuse filter stopped defining a tag and
1552          * then suddenly disappeared when someone deleted all uses of that tag.
1553          *
1554          * @param User $user
1555          * @return bool
1556          */
1557         public static function showTagEditingUI( User $user ) {
1558                 return $user->isAllowed( 'changetags' ) && (bool)self::listExplicitlyDefinedTags();
1559         }
1560 }