includes/changetags/ChangeTags.php

   1 <?php
   2 /**
   3  * Recent changes tagging.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Change tagging
  22  */
  23
  24 use MediaWiki\MediaWikiServices;
  25 use MediaWiki\Storage\NameTableAccessException;
  26 use Wikimedia\Rdbms\Database;
  27
  28 class ChangeTags {
  29         /**
  30          * Can't delete tags with more than this many uses. Similar in intent to
  31          * the bigdelete user right
  32          * @todo Use the job queue for tag deletion to avoid this restriction
  33          */
  34         const MAX_DELETE_USES = 5000;
  35
  36         /**
  37          * A list of tags defined and used by MediaWiki itself.
  38          */
  39         private static $definedSoftwareTags = [
  40                 'mw-contentmodelchange',
  41                 'mw-new-redirect',
  42                 'mw-removed-redirect',
  43                 'mw-changed-redirect-target',
  44                 'mw-blank',
  45                 'mw-replace',
  46                 'mw-rollback',
  47                 'mw-undo',
  48         ];
  49
  50         /**
  51          * Loads defined core tags, checks for invalid types (if not array),
  52          * and filters for supported and enabled (if $all is false) tags only.
  53          *
  54          * @param bool $all If true, return all valid defined tags. Otherwise, return only enabled ones.
  55          * @return array Array of all defined/enabled tags.
  56          */
  57         public static function getSoftwareTags( $all = false ) {
  58                 global $wgSoftwareTags;
  59                 $softwareTags = [];
  60
  61                 if ( !is_array( $wgSoftwareTags ) ) {
  62                         wfWarn( 'wgSoftwareTags should be associative array of enabled tags.
  63                         Please refer to documentation for the list of tags you can enable' );
  64                         return $softwareTags;
  65                 }
  66
  67                 $availableSoftwareTags = !$all ?
  68                         array_keys( array_filter( $wgSoftwareTags ) ) :
  69                         array_keys( $wgSoftwareTags );
  70
  71                 $softwareTags = array_intersect(
  72                         $availableSoftwareTags,
  73                         self::$definedSoftwareTags
  74                 );
  75
  76                 return $softwareTags;
  77         }
  78
  79         /**
  80          * Creates HTML for the given tags
  81          *
  82          * @param string $tags Comma-separated list of tags
  83          * @param string $page A label for the type of action which is being displayed,
  84          *   for example: 'history', 'contributions' or 'newpages'
  85          * @param IContextSource|null $context
  86          * @note Even though it takes null as a valid argument, an IContextSource is preferred
  87          *       in a new code, as the null value is subject to change in the future
  88          * @return array Array with two items: (html, classes)
  89          *   - html: String: HTML for displaying the tags (empty string when param $tags is empty)
  90          *   - classes: Array of strings: CSS classes used in the generated html, one class for each tag
  91          * @return-taint onlysafefor_htmlnoent
  92          */
  93         public static function formatSummaryRow( $tags, $page, IContextSource $context = null ) {
  94                 if ( !$tags ) {
  95                         return [ '', [] ];
  96                 }
  97                 if ( !$context ) {
  98                         $context = RequestContext::getMain();
  99                 }
 100
 101                 $classes = [];
 102
 103                 $tags = explode( ',', $tags );
 104                 $displayTags = [];
 105                 foreach ( $tags as $tag ) {
 106                         if ( !$tag ) {
 107                                 continue;
 108                         }
 109                         $description = self::tagDescription( $tag, $context );
 110                         if ( $description === false ) {
 111                                 continue;
 112                         }
 113                         $displayTags[] = Xml::tags(
 114                                 'span',
 115                                 [ 'class' => 'mw-tag-marker ' .
 116                                                                 Sanitizer::escapeClass( "mw-tag-marker-$tag" ) ],
 117                                 $description
 118                         );
 119                         $classes[] = Sanitizer::escapeClass( "mw-tag-$tag" );
 120                 }
 121
 122                 if ( !$displayTags ) {
 123                         return [ '', [] ];
 124                 }
 125
 126                 $markers = $context->msg( 'tag-list-wrapper' )
 127                         ->numParams( count( $displayTags ) )
 128                         ->rawParams( $context->getLanguage()->commaList( $displayTags ) )
 129                         ->parse();
 130                 $markers = Xml::tags( 'span', [ 'class' => 'mw-tag-markers' ], $markers );
 131
 132                 return [ $markers, $classes ];
 133         }
 134
 135         /**
 136          * Get a short description for a tag.
 137          *
 138          * Checks if message key "mediawiki:tag-$tag" exists. If it does not,
 139          * returns the HTML-escaped tag name. Uses the message if the message
 140          * exists, provided it is not disabled. If the message is disabled,
 141          * we consider the tag hidden, and return false.
 142          *
 143          * @param string $tag
 144          * @param IContextSource $context
 145          * @return string|bool Tag description or false if tag is to be hidden.
 146          * @since 1.25 Returns false if tag is to be hidden.
 147          */
 148         public static function tagDescription( $tag, IContextSource $context ) {
 149                 $msg = $context->msg( "tag-$tag" );
 150                 if ( !$msg->exists() ) {
 151                         // No such message, so return the HTML-escaped tag name.
 152                         return htmlspecialchars( $tag );
 153                 }
 154                 if ( $msg->isDisabled() ) {
 155                         // The message exists but is disabled, hide the tag.
 156                         return false;
 157                 }
 158
 159                 // Message exists and isn't disabled, use it.
 160                 return $msg->parse();
 161         }
 162
 163         /**
 164          * Get the message object for the tag's long description.
 165          *
 166          * Checks if message key "mediawiki:tag-$tag-description" exists. If it does not,
 167          * or if message is disabled, returns false. Otherwise, returns the message object
 168          * for the long description.
 169          *
 170          * @param string $tag
 171          * @param IContextSource $context
 172          * @return Message|bool Message object of the tag long description or false if
 173          *  there is no description.
 174          */
 175         public static function tagLongDescriptionMessage( $tag, IContextSource $context ) {
 176                 $msg = $context->msg( "tag-$tag-description" );
 177                 if ( !$msg->exists() ) {
 178                         return false;
 179                 }
 180                 if ( $msg->isDisabled() ) {
 181                         // The message exists but is disabled, hide the description.
 182                         return false;
 183                 }
 184
 185                 // Message exists and isn't disabled, use it.
 186                 return $msg;
 187         }
 188
 189         /**
 190          * Get truncated message for the tag's long description.
 191          *
 192          * @param string $tag Tag name.
 193          * @param int $length Maximum length of truncated message, including ellipsis.
 194          * @param IContextSource $context
 195          *
 196          * @return string Truncated long tag description.
 197          */
 198         public static function truncateTagDescription( $tag, $length, IContextSource $context ) {
 199                 $originalDesc = self::tagLongDescriptionMessage( $tag, $context );
 200                 // If there is no tag description, return empty string
 201                 if ( !$originalDesc ) {
 202                         return '';
 203                 }
 204
 205                 $taglessDesc = Sanitizer::stripAllTags( $originalDesc->parse() );
 206
 207                 return $context->getLanguage()->truncateForVisual( $taglessDesc, $length );
 208         }
 209
 210         /**
 211          * Add tags to a change given its rc_id, rev_id and/or log_id
 212          *
 213          * @param string|string[] $tags Tags to add to the change
 214          * @param int|null $rc_id The rc_id of the change to add the tags to
 215          * @param int|null $rev_id The rev_id of the change to add the tags to
 216          * @param int|null $log_id The log_id of the change to add the tags to
 217          * @param string|null $params Params to put in the ct_params field of table 'change_tag'
 218          * @param RecentChange|null $rc Recent change, in case the tagging accompanies the action
 219          * (this should normally be the case)
 220          *
 221          * @throws MWException
 222          * @return bool False if no changes are made, otherwise true
 223          */
 224         public static function addTags( $tags, $rc_id = null, $rev_id = null,
 225                 $log_id = null, $params = null, RecentChange $rc = null
 226         ) {
 227                 $result = self::updateTags( $tags, null, $rc_id, $rev_id, $log_id, $params, $rc );
 228                 return (bool)$result[0];
 229         }
 230
 231         /**
 232          * Add and remove tags to/from a change given its rc_id, rev_id and/or log_id,
 233          * without verifying that the tags exist or are valid. If a tag is present in
 234          * both $tagsToAdd and $tagsToRemove, it will be removed.
 235          *
 236          * This function should only be used by extensions to manipulate tags they
 237          * have registered using the ListDefinedTags hook. When dealing with user
 238          * input, call updateTagsWithChecks() instead.
 239          *
 240          * @param string|array|null $tagsToAdd Tags to add to the change
 241          * @param string|array|null $tagsToRemove Tags to remove from the change
 242          * @param int|null &$rc_id The rc_id of the change to add the tags to.
 243          * Pass a variable whose value is null if the rc_id is not relevant or unknown.
 244          * @param int|null &$rev_id The rev_id of the change to add the tags to.
 245          * Pass a variable whose value is null if the rev_id is not relevant or unknown.
 246          * @param int|null &$log_id The log_id of the change to add the tags to.
 247          * Pass a variable whose value is null if the log_id is not relevant or unknown.
 248          * @param string|null $params Params to put in the ct_params field of table
 249          * 'change_tag' when adding tags
 250          * @param RecentChange|null $rc Recent change being tagged, in case the tagging accompanies
 251          * the action
 252          * @param User|null $user Tagging user, in case the tagging is subsequent to the tagged action
 253          *
 254          * @throws MWException When $rc_id, $rev_id and $log_id are all null
 255          * @return array Index 0 is an array of tags actually added, index 1 is an
 256          * array of tags actually removed, index 2 is an array of tags present on the
 257          * revision or log entry before any changes were made
 258          *
 259          * @since 1.25
 260          */
 261         public static function updateTags( $tagsToAdd, $tagsToRemove, &$rc_id = null,
 262                 &$rev_id = null, &$log_id = null, $params = null, RecentChange $rc = null,
 263                 User $user = null
 264         ) {
 265                 global $wgChangeTagsSchemaMigrationStage;
 266
 267                 $tagsToAdd = array_filter( (array)$tagsToAdd ); // Make sure we're submitting all tags...
 268                 $tagsToRemove = array_filter( (array)$tagsToRemove );
 269
 270                 if ( !$rc_id && !$rev_id && !$log_id ) {
 271                         throw new MWException( 'At least one of: RCID, revision ID, and log ID MUST be ' .
 272                                 'specified when adding or removing a tag from a change!' );
 273                 }
 274
 275                 $dbw = wfGetDB( DB_MASTER );
 276
 277                 // Might as well look for rcids and so on.
 278                 if ( !$rc_id ) {
 279                         // Info might be out of date, somewhat fractionally, on replica DB.
 280                         // LogEntry/LogPage and WikiPage match rev/log/rc timestamps,
 281                         // so use that relation to avoid full table scans.
 282                         if ( $log_id ) {
 283                                 $rc_id = $dbw->selectField(
 284                                         [ 'logging', 'recentchanges' ],
 285                                         'rc_id',
 286                                         [
 287                                                 'log_id' => $log_id,
 288                                                 'rc_timestamp = log_timestamp',
 289                                                 'rc_logid = log_id'
 290                                         ],
 291                                         __METHOD__
 292                                 );
 293                         } elseif ( $rev_id ) {
 294                                 $rc_id = $dbw->selectField(
 295                                         [ 'revision', 'recentchanges' ],
 296                                         'rc_id',
 297                                         [
 298                                                 'rev_id' => $rev_id,
 299                                                 'rc_timestamp = rev_timestamp',
 300                                                 'rc_this_oldid = rev_id'
 301                                         ],
 302                                         __METHOD__
 303                                 );
 304                         }
 305                 } elseif ( !$log_id && !$rev_id ) {
 306                         // Info might be out of date, somewhat fractionally, on replica DB.
 307                         $log_id = $dbw->selectField(
 308                                 'recentchanges',
 309                                 'rc_logid',
 310                                 [ 'rc_id' => $rc_id ],
 311                                 __METHOD__
 312                         );
 313                         $rev_id = $dbw->selectField(
 314                                 'recentchanges',
 315                                 'rc_this_oldid',
 316                                 [ 'rc_id' => $rc_id ],
 317                                 __METHOD__
 318                         );
 319                 }
 320
 321                 if ( $log_id && !$rev_id ) {
 322                         $rev_id = $dbw->selectField(
 323                                 'log_search',
 324                                 'ls_value',
 325                                 [ 'ls_field' => 'associated_rev_id', 'ls_log_id' => $log_id ],
 326                                 __METHOD__
 327                         );
 328                 } elseif ( !$log_id && $rev_id ) {
 329                         $log_id = $dbw->selectField(
 330                                 'log_search',
 331                                 'ls_log_id',
 332                                 [ 'ls_field' => 'associated_rev_id', 'ls_value' => $rev_id ],
 333                                 __METHOD__
 334                         );
 335                 }
 336
 337                 // update the tag_summary row
 338                 $prevTags = [];
 339                 if ( !self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $rc_id, $rev_id,
 340                         $log_id, $prevTags )
 341                 ) {
 342                         // nothing to do
 343                         return [ [], [], $prevTags ];
 344                 }
 345
 346                 // insert a row into change_tag for each new tag
 347                 $changeTagDefStore = MediaWikiServices::getInstance()->getChangeTagDefStore();
 348                 if ( count( $tagsToAdd ) ) {
 349                         $changeTagMapping = [];
 350                         if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
 351                                 foreach ( $tagsToAdd as $tag ) {
 352                                         $changeTagMapping[$tag] = $changeTagDefStore->acquireId( $tag );
 353                                 }
 354                                 // T207881: update the counts at the end of the transaction
 355                                 $dbw->onTransactionPreCommitOrIdle( function () use ( $dbw, $tagsToAdd ) {
 356                                         $dbw->update(
 357                                                 'change_tag_def',
 358                                                 [ 'ctd_count = ctd_count + 1' ],
 359                                                 [ 'ctd_name' => $tagsToAdd ],
 360                                                 __METHOD__
 361                                         );
 362                                 } );
 363                         }
 364
 365                         $tagsRows = [];
 366                         foreach ( $tagsToAdd as $tag ) {
 367                                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_WRITE_BOTH ) {
 368                                         $tagName = null;
 369                                 } else {
 370                                         $tagName = $tag;
 371                                 }
 372                                 // Filter so we don't insert NULLs as zero accidentally.
 373                                 // Keep in mind that $rc_id === null means "I don't care/know about the
 374                                 // rc_id, just delete $tag on this revision/log entry". It doesn't
 375                                 // mean "only delete tags on this revision/log WHERE rc_id IS NULL".
 376                                 $tagsRows[] = array_filter(
 377                                         [
 378                                                 'ct_tag' => $tagName,
 379                                                 'ct_rc_id' => $rc_id,
 380                                                 'ct_log_id' => $log_id,
 381                                                 'ct_rev_id' => $rev_id,
 382                                                 'ct_params' => $params,
 383                                                 'ct_tag_id' => $changeTagMapping[$tag] ?? null,
 384                                         ]
 385                                 );
 386
 387                         }
 388
 389                         $dbw->insert( 'change_tag', $tagsRows, __METHOD__, [ 'IGNORE' ] );
 390                 }
 391
 392                 // delete from change_tag
 393                 if ( count( $tagsToRemove ) ) {
 394                         foreach ( $tagsToRemove as $tag ) {
 395                                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_WRITE_BOTH ) {
 396                                         $tagName = null;
 397                                         $tagId = $changeTagDefStore->getId( $tag );
 398                                 } else {
 399                                         $tagName = $tag;
 400                                         $tagId = null;
 401                                 }
 402                                 $conds = array_filter(
 403                                         [
 404                                                 'ct_tag' => $tagName,
 405                                                 'ct_rc_id' => $rc_id,
 406                                                 'ct_log_id' => $log_id,
 407                                                 'ct_rev_id' => $rev_id,
 408                                                 'ct_tag_id' => $tagId,
 409                                         ]
 410                                 );
 411                                 $dbw->delete( 'change_tag', $conds, __METHOD__ );
 412                                 if ( $dbw->affectedRows() && $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
 413                                         // T207881: update the counts at the end of the transaction
 414                                         $dbw->onTransactionPreCommitOrIdle( function () use ( $dbw, $tag ) {
 415                                                 $dbw->update(
 416                                                         'change_tag_def',
 417                                                         [ 'ctd_count = ctd_count - 1' ],
 418                                                         [ 'ctd_name' => $tag ],
 419                                                         __METHOD__
 420                                                 );
 421
 422                                                 $dbw->delete(
 423                                                         'change_tag_def',
 424                                                         [ 'ctd_name' => $tag, 'ctd_count' => 0, 'ctd_user_defined' => 0 ],
 425                                                         __METHOD__
 426                                                 );
 427                                         } );
 428                                 }
 429                         }
 430                 }
 431
 432                 self::purgeTagUsageCache();
 433
 434                 Hooks::run( 'ChangeTagsAfterUpdateTags', [ $tagsToAdd, $tagsToRemove, $prevTags,
 435                         $rc_id, $rev_id, $log_id, $params, $rc, $user ] );
 436
 437                 return [ $tagsToAdd, $tagsToRemove, $prevTags ];
 438         }
 439
 440         /**
 441          * Adds or removes a given set of tags to/from the relevant row of the
 442          * tag_summary table. Modifies the tagsToAdd and tagsToRemove arrays to
 443          * reflect the tags that were actually added and/or removed.
 444          *
 445          * @param array &$tagsToAdd
 446          * @param array &$tagsToRemove If a tag is present in both $tagsToAdd and
 447          * $tagsToRemove, it will be removed
 448          * @param int|null $rc_id Null if not known or not applicable
 449          * @param int|null $rev_id Null if not known or not applicable
 450          * @param int|null $log_id Null if not known or not applicable
 451          * @param array &$prevTags Optionally outputs a list of the tags that were
 452          * in the tag_summary row to begin with
 453          * @return bool True if any modifications were made, otherwise false
 454          * @since 1.25
 455          */
 456         protected static function updateTagSummaryRow( &$tagsToAdd, &$tagsToRemove,
 457                 $rc_id, $rev_id, $log_id, &$prevTags = []
 458         ) {
 459                 $dbw = wfGetDB( DB_MASTER );
 460
 461                 $tsConds = array_filter( [
 462                         'ts_rc_id' => $rc_id,
 463                         'ts_rev_id' => $rev_id,
 464                         'ts_log_id' => $log_id
 465                 ] );
 466
 467                 // Can't both add and remove a tag at the same time...
 468                 $tagsToAdd = array_diff( $tagsToAdd, $tagsToRemove );
 469
 470                 // Update the summary row.
 471                 // $prevTags can be out of date on replica DBs, especially when addTags is called consecutively,
 472                 // causing loss of tags added recently in tag_summary table.
 473                 $prevTags = $dbw->selectField( 'tag_summary', 'ts_tags', $tsConds, __METHOD__ );
 474                 $prevTags = $prevTags ?: '';
 475                 $prevTags = array_filter( explode( ',', $prevTags ) );
 476
 477                 // add tags
 478                 $tagsToAdd = array_values( array_diff( $tagsToAdd, $prevTags ) );
 479                 $newTags = array_unique( array_merge( $prevTags, $tagsToAdd ) );
 480
 481                 // remove tags
 482                 $tagsToRemove = array_values( array_intersect( $tagsToRemove, $newTags ) );
 483                 $newTags = array_values( array_diff( $newTags, $tagsToRemove ) );
 484
 485                 sort( $prevTags );
 486                 sort( $newTags );
 487                 if ( $prevTags == $newTags ) {
 488                         return false;
 489                 }
 490
 491                 if ( !$newTags ) {
 492                         // No tags left, so delete the row altogether
 493                         $dbw->delete( 'tag_summary', $tsConds, __METHOD__ );
 494                 } else {
 495                         // Specify the non-DEFAULT value columns in the INSERT/REPLACE clause
 496                         $row = array_filter( [ 'ts_tags' => implode( ',', $newTags ) ] + $tsConds );
 497                         // Check the unique keys for conflicts, ignoring any NULL *_id values
 498                         $uniqueKeys = [];
 499                         foreach ( [ 'ts_rev_id', 'ts_rc_id', 'ts_log_id' ] as $uniqueColumn ) {
 500                                 if ( isset( $row[$uniqueColumn] ) ) {
 501                                         $uniqueKeys[] = [ $uniqueColumn ];
 502                                 }
 503                         }
 504
 505                         $dbw->replace( 'tag_summary', $uniqueKeys, $row, __METHOD__ );
 506                 }
 507
 508                 return true;
 509         }
 510
 511         /**
 512          * Helper function to generate a fatal status with a 'not-allowed' type error.
 513          *
 514          * @param string $msgOne Message key to use in the case of one tag
 515          * @param string $msgMulti Message key to use in the case of more than one tag
 516          * @param array $tags Restricted tags (passed as $1 into the message, count of
 517          * $tags passed as $2)
 518          * @return Status
 519          * @since 1.25
 520          */
 521         protected static function restrictedTagError( $msgOne, $msgMulti, $tags ) {
 522                 $lang = RequestContext::getMain()->getLanguage();
 523                 $count = count( $tags );
 524                 return Status::newFatal( ( $count > 1 ) ? $msgMulti : $msgOne,
 525                         $lang->commaList( $tags ), $count );
 526         }
 527
 528         /**
 529          * Is it OK to allow the user to apply all the specified tags at the same time
 530          * as they edit/make the change?
 531          *
 532          * Extensions should not use this function, unless directly handling a user
 533          * request to add a tag to a revision or log entry that the user is making.
 534          *
 535          * @param array $tags Tags that you are interested in applying
 536          * @param User|null $user User whose permission you wish to check, or null to
 537          * check for a generic non-blocked user with the relevant rights
 538          * @return Status
 539          * @since 1.25
 540          */
 541         public static function canAddTagsAccompanyingChange( array $tags, User $user = null ) {
 542                 if ( !is_null( $user ) ) {
 543                         if ( !$user->isAllowed( 'applychangetags' ) ) {
 544                                 return Status::newFatal( 'tags-apply-no-permission' );
 545                         } elseif ( $user->isBlocked() ) {
 546                                 return Status::newFatal( 'tags-apply-blocked', $user->getName() );
 547                         }
 548                 }
 549
 550                 // to be applied, a tag has to be explicitly defined
 551                 $allowedTags = self::listExplicitlyDefinedTags();
 552                 Hooks::run( 'ChangeTagsAllowedAdd', [ &$allowedTags, $tags, $user ] );
 553                 $disallowedTags = array_diff( $tags, $allowedTags );
 554                 if ( $disallowedTags ) {
 555                         return self::restrictedTagError( 'tags-apply-not-allowed-one',
 556                                 'tags-apply-not-allowed-multi', $disallowedTags );
 557                 }
 558
 559                 return Status::newGood();
 560         }
 561
 562         /**
 563          * Adds tags to a given change, checking whether it is allowed first, but
 564          * without adding a log entry. Useful for cases where the tag is being added
 565          * along with the action that generated the change (e.g. tagging an edit as
 566          * it is being made).
 567          *
 568          * Extensions should not use this function, unless directly handling a user
 569          * request to add a particular tag. Normally, extensions should call
 570          * ChangeTags::updateTags() instead.
 571          *
 572          * @param array $tags Tags to apply
 573          * @param int|null $rc_id The rc_id of the change to add the tags to
 574          * @param int|null $rev_id The rev_id of the change to add the tags to
 575          * @param int|null $log_id The log_id of the change to add the tags to
 576          * @param string $params Params to put in the ct_params field of table
 577          * 'change_tag' when adding tags
 578          * @param User $user Who to give credit for the action
 579          * @return Status
 580          * @since 1.25
 581          */
 582         public static function addTagsAccompanyingChangeWithChecks(
 583                 array $tags, $rc_id, $rev_id, $log_id, $params, User $user
 584         ) {
 585                 // are we allowed to do this?
 586                 $result = self::canAddTagsAccompanyingChange( $tags, $user );
 587                 if ( !$result->isOK() ) {
 588                         $result->value = null;
 589                         return $result;
 590                 }
 591
 592                 // do it!
 593                 self::addTags( $tags, $rc_id, $rev_id, $log_id, $params );
 594
 595                 return Status::newGood( true );
 596         }
 597
 598         /**
 599          * Is it OK to allow the user to adds and remove the given tags tags to/from a
 600          * change?
 601          *
 602          * Extensions should not use this function, unless directly handling a user
 603          * request to add or remove tags from an existing revision or log entry.
 604          *
 605          * @param array $tagsToAdd Tags that you are interested in adding
 606          * @param array $tagsToRemove Tags that you are interested in removing
 607          * @param User|null $user User whose permission you wish to check, or null to
 608          * check for a generic non-blocked user with the relevant rights
 609          * @return Status
 610          * @since 1.25
 611          */
 612         public static function canUpdateTags( array $tagsToAdd, array $tagsToRemove,
 613                 User $user = null
 614         ) {
 615                 if ( !is_null( $user ) ) {
 616                         if ( !$user->isAllowed( 'changetags' ) ) {
 617                                 return Status::newFatal( 'tags-update-no-permission' );
 618                         } elseif ( $user->isBlocked() ) {
 619                                 return Status::newFatal( 'tags-update-blocked', $user->getName() );
 620                         }
 621                 }
 622
 623                 if ( $tagsToAdd ) {
 624                         // to be added, a tag has to be explicitly defined
 625                         // @todo Allow extensions to define tags that can be applied by users...
 626                         $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
 627                         $diff = array_diff( $tagsToAdd, $explicitlyDefinedTags );
 628                         if ( $diff ) {
 629                                 return self::restrictedTagError( 'tags-update-add-not-allowed-one',
 630                                         'tags-update-add-not-allowed-multi', $diff );
 631                         }
 632                 }
 633
 634                 if ( $tagsToRemove ) {
 635                         // to be removed, a tag must not be defined by an extension, or equivalently it
 636                         // has to be either explicitly defined or not defined at all
 637                         // (assuming no edge case of a tag both explicitly-defined and extension-defined)
 638                         $softwareDefinedTags = self::listSoftwareDefinedTags();
 639                         $intersect = array_intersect( $tagsToRemove, $softwareDefinedTags );
 640                         if ( $intersect ) {
 641                                 return self::restrictedTagError( 'tags-update-remove-not-allowed-one',
 642                                         'tags-update-remove-not-allowed-multi', $intersect );
 643                         }
 644                 }
 645
 646                 return Status::newGood();
 647         }
 648
 649         /**
 650          * Adds and/or removes tags to/from a given change, checking whether it is
 651          * allowed first, and adding a log entry afterwards.
 652          *
 653          * Includes a call to ChangeTags::canUpdateTags(), so your code doesn't need
 654          * to do that. However, it doesn't check whether the *_id parameters are a
 655          * valid combination. That is up to you to enforce. See ApiTag::execute() for
 656          * an example.
 657          *
 658          * Extensions should generally avoid this function. Call
 659          * ChangeTags::updateTags() instead, unless directly handling a user request
 660          * to add or remove tags from an existing revision or log entry.
 661          *
 662          * @param array|null $tagsToAdd If none, pass array() or null
 663          * @param array|null $tagsToRemove If none, pass array() or null
 664          * @param int|null $rc_id The rc_id of the change to add the tags to
 665          * @param int|null $rev_id The rev_id of the change to add the tags to
 666          * @param int|null $log_id The log_id of the change to add the tags to
 667          * @param string $params Params to put in the ct_params field of table
 668          * 'change_tag' when adding tags
 669          * @param string $reason Comment for the log
 670          * @param User $user Who to give credit for the action
 671          * @return Status If successful, the value of this Status object will be an
 672          * object (stdClass) with the following fields:
 673          *  - logId: the ID of the added log entry, or null if no log entry was added
 674          *    (i.e. no operation was performed)
 675          *  - addedTags: an array containing the tags that were actually added
 676          *  - removedTags: an array containing the tags that were actually removed
 677          * @since 1.25
 678          */
 679         public static function updateTagsWithChecks( $tagsToAdd, $tagsToRemove,
 680                 $rc_id, $rev_id, $log_id, $params, $reason, User $user
 681         ) {
 682                 if ( is_null( $tagsToAdd ) ) {
 683                         $tagsToAdd = [];
 684                 }
 685                 if ( is_null( $tagsToRemove ) ) {
 686                         $tagsToRemove = [];
 687                 }
 688                 if ( !$tagsToAdd && !$tagsToRemove ) {
 689                         // no-op, don't bother
 690                         return Status::newGood( (object)[
 691                                 'logId' => null,
 692                                 'addedTags' => [],
 693                                 'removedTags' => [],
 694                         ] );
 695                 }
 696
 697                 // are we allowed to do this?
 698                 $result = self::canUpdateTags( $tagsToAdd, $tagsToRemove, $user );
 699                 if ( !$result->isOK() ) {
 700                         $result->value = null;
 701                         return $result;
 702                 }
 703
 704                 // basic rate limiting
 705                 if ( $user->pingLimiter( 'changetag' ) ) {
 706                         return Status::newFatal( 'actionthrottledtext' );
 707                 }
 708
 709                 // do it!
 710                 list( $tagsAdded, $tagsRemoved, $initialTags ) = self::updateTags( $tagsToAdd,
 711                         $tagsToRemove, $rc_id, $rev_id, $log_id, $params, null, $user );
 712                 if ( !$tagsAdded && !$tagsRemoved ) {
 713                         // no-op, don't log it
 714                         return Status::newGood( (object)[
 715                                 'logId' => null,
 716                                 'addedTags' => [],
 717                                 'removedTags' => [],
 718                         ] );
 719                 }
 720
 721                 // log it
 722                 $logEntry = new ManualLogEntry( 'tag', 'update' );
 723                 $logEntry->setPerformer( $user );
 724                 $logEntry->setComment( $reason );
 725
 726                 // find the appropriate target page
 727                 if ( $rev_id ) {
 728                         $rev = Revision::newFromId( $rev_id );
 729                         if ( $rev ) {
 730                                 $logEntry->setTarget( $rev->getTitle() );
 731                         }
 732                 } elseif ( $log_id ) {
 733                         // This function is from revision deletion logic and has nothing to do with
 734                         // change tags, but it appears to be the only other place in core where we
 735                         // perform logged actions on log items.
 736                         $logEntry->setTarget( RevDelLogList::suggestTarget( null, [ $log_id ] ) );
 737                 }
 738
 739                 if ( !$logEntry->getTarget() ) {
 740                         // target is required, so we have to set something
 741                         $logEntry->setTarget( SpecialPage::getTitleFor( 'Tags' ) );
 742                 }
 743
 744                 $logParams = [
 745                         '4::revid' => $rev_id,
 746                         '5::logid' => $log_id,
 747                         '6:list:tagsAdded' => $tagsAdded,
 748                         '7:number:tagsAddedCount' => count( $tagsAdded ),
 749                         '8:list:tagsRemoved' => $tagsRemoved,
 750                         '9:number:tagsRemovedCount' => count( $tagsRemoved ),
 751                         'initialTags' => $initialTags,
 752                 ];
 753                 $logEntry->setParameters( $logParams );
 754                 $logEntry->setRelations( [ 'Tag' => array_merge( $tagsAdded, $tagsRemoved ) ] );
 755
 756                 $dbw = wfGetDB( DB_MASTER );
 757                 $logId = $logEntry->insert( $dbw );
 758                 // Only send this to UDP, not RC, similar to patrol events
 759                 $logEntry->publish( $logId, 'udp' );
 760
 761                 return Status::newGood( (object)[
 762                         'logId' => $logId,
 763                         'addedTags' => $tagsAdded,
 764                         'removedTags' => $tagsRemoved,
 765                 ] );
 766         }
 767
 768         /**
 769          * Applies all tags-related changes to a query.
 770          * Handles selecting tags, and filtering.
 771          * Needs $tables to be set up properly, so we can figure out which join conditions to use.
 772          *
 773          * WARNING: If $filter_tag contains more than one tag, this function will add DISTINCT,
 774          * which may cause performance problems for your query unless you put the ID field of your
 775          * table at the end of the ORDER BY, and set a GROUP BY equal to the ORDER BY. For example,
 776          * if you had ORDER BY foo_timestamp DESC, you will now need GROUP BY foo_timestamp, foo_id
 777          * ORDER BY foo_timestamp DESC, foo_id DESC.
 778          *
 779          * @param string|array &$tables Table names, see Database::select
 780          * @param string|array &$fields Fields used in query, see Database::select
 781          * @param string|array &$conds Conditions used in query, see Database::select
 782          * @param array &$join_conds Join conditions, see Database::select
 783          * @param string|array &$options Options, see Database::select
 784          * @param string|array $filter_tag Tag(s) to select on
 785          *
 786          * @throws MWException When unable to determine appropriate JOIN condition for tagging
 787          */
 788         public static function modifyDisplayQuery( &$tables, &$fields, &$conds,
 789                 &$join_conds, &$options, $filter_tag = ''
 790         ) {
 791                 global $wgUseTagFilter, $wgChangeTagsSchemaMigrationStage;
 792
 793                 // Normalize to arrays
 794                 $tables = (array)$tables;
 795                 $fields = (array)$fields;
 796                 $conds = (array)$conds;
 797                 $options = (array)$options;
 798
 799                 // Figure out which ID field to use
 800                 if ( in_array( 'recentchanges', $tables ) ) {
 801                         $join_cond = 'ct_rc_id=rc_id';
 802                 } elseif ( in_array( 'logging', $tables ) ) {
 803                         $join_cond = 'ct_log_id=log_id';
 804                 } elseif ( in_array( 'revision', $tables ) ) {
 805                         $join_cond = 'ct_rev_id=rev_id';
 806                 } elseif ( in_array( 'archive', $tables ) ) {
 807                         $join_cond = 'ct_rev_id=ar_rev_id';
 808                 } else {
 809                         throw new MWException( 'Unable to determine appropriate JOIN condition for tagging.' );
 810                 }
 811
 812                 $tagTables[] = 'change_tag';
 813                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_WRITE_BOTH ) {
 814                         $tagTables[] = 'change_tag_def';
 815                         $join_cond_ts_tags = [ 'change_tag_def' => [ 'INNER JOIN', 'ct_tag_id=ctd_id' ] ];
 816                         $field = 'ctd_name';
 817                 } else {
 818                         $field = 'ct_tag';
 819                         $join_cond_ts_tags = [];
 820                 }
 821
 822                 $fields['ts_tags'] = wfGetDB( DB_REPLICA )->buildGroupConcatField(
 823                         ',', $tagTables, $field, $join_cond, $join_cond_ts_tags
 824                 );
 825
 826                 if ( $wgUseTagFilter && $filter_tag ) {
 827                         // Somebody wants to filter on a tag.
 828                         // Add an INNER JOIN on change_tag
 829
 830                         $tables[] = 'change_tag';
 831                         $join_conds['change_tag'] = [ 'INNER JOIN', $join_cond ];
 832                         if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_WRITE_BOTH ) {
 833                                 $filterTagIds = [];
 834                                 $changeTagDefStore = MediaWikiServices::getInstance()->getChangeTagDefStore();
 835                                 foreach ( (array)$filter_tag as $filterTagName ) {
 836                                         try {
 837                                                 $filterTagIds[] = $changeTagDefStore->getId( $filterTagName );
 838                                         } catch ( NameTableAccessException $exception ) {
 839                                                 // Return nothing.
 840                                                 $conds[] = '0';
 841                                                 break;
 842                                         };
 843                                 }
 844
 845                                 if ( $filterTagIds !== [] ) {
 846                                         $conds['ct_tag_id'] = $filterTagIds;
 847                                 }
 848                         } else {
 849                                 $conds['ct_tag'] = $filter_tag;
 850                         }
 851
 852                         if (
 853                                 is_array( $filter_tag ) && count( $filter_tag ) > 1 &&
 854                                 !in_array( 'DISTINCT', $options )
 855                         ) {
 856                                 $options[] = 'DISTINCT';
 857                         }
 858                 }
 859         }
 860
 861         /**
 862          * Build a text box to select a change tag
 863          *
 864          * @param string $selected Tag to select by default
 865          * @param bool $ooui Use an OOUI TextInputWidget as selector instead of a non-OOUI input field
 866          *        You need to call OutputPage::enableOOUI() yourself.
 867          * @param IContextSource|null $context
 868          * @note Even though it takes null as a valid argument, an IContextSource is preferred
 869          *       in a new code, as the null value can change in the future
 870          * @return array an array of (label, selector)
 871          */
 872         public static function buildTagFilterSelector(
 873                 $selected = '', $ooui = false, IContextSource $context = null
 874         ) {
 875                 if ( !$context ) {
 876                         $context = RequestContext::getMain();
 877                 }
 878
 879                 $config = $context->getConfig();
 880                 if ( !$config->get( 'UseTagFilter' ) || !count( self::listDefinedTags() ) ) {
 881                         return [];
 882                 }
 883
 884                 $data = [
 885                         Html::rawElement(
 886                                 'label',
 887                                 [ 'for' => 'tagfilter' ],
 888                                 $context->msg( 'tag-filter' )->parse()
 889                         )
 890                 ];
 891
 892                 if ( $ooui ) {
 893                         $data[] = new OOUI\TextInputWidget( [
 894                                 'id' => 'tagfilter',
 895                                 'name' => 'tagfilter',
 896                                 'value' => $selected,
 897                                 'classes' => 'mw-tagfilter-input',
 898                         ] );
 899                 } else {
 900                         $data[] = Xml::input(
 901                                 'tagfilter',
 902                                 20,
 903                                 $selected,
 904                                 [ 'class' => 'mw-tagfilter-input mw-ui-input mw-ui-input-inline', 'id' => 'tagfilter' ]
 905                         );
 906                 }
 907
 908                 return $data;
 909         }
 910
 911         /**
 912          * Defines a tag in the valid_tag table and/or update ctd_user_defined field in change_tag_def,
 913          * without checking that the tag name is valid.
 914          * Extensions should NOT use this function; they can use the ListDefinedTags
 915          * hook instead.
 916          *
 917          * @param string $tag Tag to create
 918          * @since 1.25
 919          */
 920         public static function defineTag( $tag ) {
 921                 global $wgChangeTagsSchemaMigrationStage;
 922
 923                 $dbw = wfGetDB( DB_MASTER );
 924                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
 925                         $tagDef = [
 926                                 'ctd_name' => $tag,
 927                                 'ctd_user_defined' => 1,
 928                                 'ctd_count' => 0
 929                         ];
 930                         $dbw->upsert(
 931                                 'change_tag_def',
 932                                 $tagDef,
 933                                 [ 'ctd_name' ],
 934                                 [ 'ctd_user_defined' => 1 ],
 935                                 __METHOD__
 936                         );
 937                 }
 938
 939                 if ( $wgChangeTagsSchemaMigrationStage < MIGRATION_NEW ) {
 940                         $dbw->replace(
 941                                 'valid_tag',
 942                                 [ 'vt_tag' ],
 943                                 [ 'vt_tag' => $tag ],
 944                                 __METHOD__
 945                         );
 946                 }
 947                 // clear the memcache of defined tags
 948                 self::purgeTagCacheAll();
 949         }
 950
 951         /**
 952          * Removes a tag from the valid_tag table and/or update ctd_user_defined field in change_tag_def.
 953          * The tag may remain in use by extensions, and may still show up as 'defined'
 954          * if an extension is setting it from the ListDefinedTags hook.
 955          *
 956          * @param string $tag Tag to remove
 957          * @since 1.25
 958          */
 959         public static function undefineTag( $tag ) {
 960                 global $wgChangeTagsSchemaMigrationStage;
 961
 962                 $dbw = wfGetDB( DB_MASTER );
 963
 964                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
 965                         $dbw->update(
 966                                 'change_tag_def',
 967                                 [ 'ctd_user_defined' => 0 ],
 968                                 [ 'ctd_name' => $tag ],
 969                                 __METHOD__
 970                         );
 971
 972                         $dbw->delete(
 973                                 'change_tag_def',
 974                                 [ 'ctd_name' => $tag, 'ctd_count' => 0 ],
 975                                 __METHOD__
 976                         );
 977                 }
 978
 979                 if ( $wgChangeTagsSchemaMigrationStage < MIGRATION_NEW ) {
 980                         $dbw->delete( 'valid_tag', [ 'vt_tag' => $tag ], __METHOD__ );
 981                 }
 982
 983                 // clear the memcache of defined tags
 984                 self::purgeTagCacheAll();
 985         }
 986
 987         /**
 988          * Writes a tag action into the tag management log.
 989          *
 990          * @param string $action
 991          * @param string $tag
 992          * @param string $reason
 993          * @param User $user Who to attribute the action to
 994          * @param int|null $tagCount For deletion only, how many usages the tag had before
 995          * it was deleted.
 996          * @param array $logEntryTags Change tags to apply to the entry
 997          * that will be created in the tag management log
 998          * @return int ID of the inserted log entry
 999          * @since 1.25
1000          */
1001         protected static function logTagManagementAction( $action, $tag, $reason,
1002                 User $user, $tagCount = null, array $logEntryTags = []
1003         ) {
1004                 $dbw = wfGetDB( DB_MASTER );
1005
1006                 $logEntry = new ManualLogEntry( 'managetags', $action );
1007                 $logEntry->setPerformer( $user );
1008                 // target page is not relevant, but it has to be set, so we just put in
1009                 // the title of Special:Tags
1010                 $logEntry->setTarget( Title::newFromText( 'Special:Tags' ) );
1011                 $logEntry->setComment( $reason );
1012
1013                 $params = [ '4::tag' => $tag ];
1014                 if ( !is_null( $tagCount ) ) {
1015                         $params['5:number:count'] = $tagCount;
1016                 }
1017                 $logEntry->setParameters( $params );
1018                 $logEntry->setRelations( [ 'Tag' => $tag ] );
1019                 $logEntry->setTags( $logEntryTags );
1020
1021                 $logId = $logEntry->insert( $dbw );
1022                 $logEntry->publish( $logId );
1023                 return $logId;
1024         }
1025
1026         /**
1027          * Is it OK to allow the user to activate this tag?
1028          *
1029          * @param string $tag Tag that you are interested in activating
1030          * @param User|null $user User whose permission you wish to check, or null if
1031          * you don't care (e.g. maintenance scripts)
1032          * @return Status
1033          * @since 1.25
1034          */
1035         public static function canActivateTag( $tag, User $user = null ) {
1036                 if ( !is_null( $user ) ) {
1037                         if ( !$user->isAllowed( 'managechangetags' ) ) {
1038                                 return Status::newFatal( 'tags-manage-no-permission' );
1039                         } elseif ( $user->isBlocked() ) {
1040                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1041                         }
1042                 }
1043
1044                 // defined tags cannot be activated (a defined tag is either extension-
1045                 // defined, in which case the extension chooses whether or not to active it;
1046                 // or user-defined, in which case it is considered active)
1047                 $definedTags = self::listDefinedTags();
1048                 if ( in_array( $tag, $definedTags ) ) {
1049                         return Status::newFatal( 'tags-activate-not-allowed', $tag );
1050                 }
1051
1052                 // non-existing tags cannot be activated
1053                 $tagUsage = self::tagUsageStatistics();
1054                 if ( !isset( $tagUsage[$tag] ) ) { // we already know the tag is undefined
1055                         return Status::newFatal( 'tags-activate-not-found', $tag );
1056                 }
1057
1058                 return Status::newGood();
1059         }
1060
1061         /**
1062          * Activates a tag, checking whether it is allowed first, and adding a log
1063          * entry afterwards.
1064          *
1065          * Includes a call to ChangeTag::canActivateTag(), so your code doesn't need
1066          * to do that.
1067          *
1068          * @param string $tag
1069          * @param string $reason
1070          * @param User $user Who to give credit for the action
1071          * @param bool $ignoreWarnings Can be used for API interaction, default false
1072          * @param array $logEntryTags Change tags to apply to the entry
1073          * that will be created in the tag management log
1074          * @return Status If successful, the Status contains the ID of the added log
1075          * entry as its value
1076          * @since 1.25
1077          */
1078         public static function activateTagWithChecks( $tag, $reason, User $user,
1079                 $ignoreWarnings = false, array $logEntryTags = []
1080         ) {
1081                 // are we allowed to do this?
1082                 $result = self::canActivateTag( $tag, $user );
1083                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1084                         $result->value = null;
1085                         return $result;
1086                 }
1087
1088                 // do it!
1089                 self::defineTag( $tag );
1090
1091                 // log it
1092                 $logId = self::logTagManagementAction( 'activate', $tag, $reason, $user,
1093                         null, $logEntryTags );
1094
1095                 return Status::newGood( $logId );
1096         }
1097
1098         /**
1099          * Is it OK to allow the user to deactivate this tag?
1100          *
1101          * @param string $tag Tag that you are interested in deactivating
1102          * @param User|null $user User whose permission you wish to check, or null if
1103          * you don't care (e.g. maintenance scripts)
1104          * @return Status
1105          * @since 1.25
1106          */
1107         public static function canDeactivateTag( $tag, User $user = null ) {
1108                 if ( !is_null( $user ) ) {
1109                         if ( !$user->isAllowed( 'managechangetags' ) ) {
1110                                 return Status::newFatal( 'tags-manage-no-permission' );
1111                         } elseif ( $user->isBlocked() ) {
1112                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1113                         }
1114                 }
1115
1116                 // only explicitly-defined tags can be deactivated
1117                 $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
1118                 if ( !in_array( $tag, $explicitlyDefinedTags ) ) {
1119                         return Status::newFatal( 'tags-deactivate-not-allowed', $tag );
1120                 }
1121                 return Status::newGood();
1122         }
1123
1124         /**
1125          * Deactivates a tag, checking whether it is allowed first, and adding a log
1126          * entry afterwards.
1127          *
1128          * Includes a call to ChangeTag::canDeactivateTag(), so your code doesn't need
1129          * to do that.
1130          *
1131          * @param string $tag
1132          * @param string $reason
1133          * @param User $user Who to give credit for the action
1134          * @param bool $ignoreWarnings Can be used for API interaction, default false
1135          * @param array $logEntryTags Change tags to apply to the entry
1136          * that will be created in the tag management log
1137          * @return Status If successful, the Status contains the ID of the added log
1138          * entry as its value
1139          * @since 1.25
1140          */
1141         public static function deactivateTagWithChecks( $tag, $reason, User $user,
1142                 $ignoreWarnings = false, array $logEntryTags = []
1143         ) {
1144                 // are we allowed to do this?
1145                 $result = self::canDeactivateTag( $tag, $user );
1146                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1147                         $result->value = null;
1148                         return $result;
1149                 }
1150
1151                 // do it!
1152                 self::undefineTag( $tag );
1153
1154                 // log it
1155                 $logId = self::logTagManagementAction( 'deactivate', $tag, $reason, $user,
1156                         null, $logEntryTags );
1157
1158                 return Status::newGood( $logId );
1159         }
1160
1161         /**
1162          * Is the tag name valid?
1163          *
1164          * @param string $tag Tag that you are interested in creating
1165          * @return Status
1166          * @since 1.30
1167          */
1168         public static function isTagNameValid( $tag ) {
1169                 // no empty tags
1170                 if ( $tag === '' ) {
1171                         return Status::newFatal( 'tags-create-no-name' );
1172                 }
1173
1174                 // tags cannot contain commas (used as a delimiter in tag_summary table),
1175                 // pipe (used as a delimiter between multiple tags in
1176                 // SpecialRecentchanges and friends), or slashes (would break tag description messages in
1177                 // MediaWiki namespace)
1178                 if ( strpos( $tag, ',' ) !== false || strpos( $tag, '|' ) !== false
1179                         || strpos( $tag, '/' ) !== false ) {
1180                         return Status::newFatal( 'tags-create-invalid-chars' );
1181                 }
1182
1183                 // could the MediaWiki namespace description messages be created?
1184                 $title = Title::makeTitleSafe( NS_MEDIAWIKI, "Tag-$tag-description" );
1185                 if ( is_null( $title ) ) {
1186                         return Status::newFatal( 'tags-create-invalid-title-chars' );
1187                 }
1188
1189                 return Status::newGood();
1190         }
1191
1192         /**
1193          * Is it OK to allow the user to create this tag?
1194          *
1195          * Extensions should NOT use this function. In most cases, a tag can be
1196          * defined using the ListDefinedTags hook without any checking.
1197          *
1198          * @param string $tag Tag that you are interested in creating
1199          * @param User|null $user User whose permission you wish to check, or null if
1200          * you don't care (e.g. maintenance scripts)
1201          * @return Status
1202          * @since 1.25
1203          */
1204         public static function canCreateTag( $tag, User $user = null ) {
1205                 if ( !is_null( $user ) ) {
1206                         if ( !$user->isAllowed( 'managechangetags' ) ) {
1207                                 return Status::newFatal( 'tags-manage-no-permission' );
1208                         } elseif ( $user->isBlocked() ) {
1209                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1210                         }
1211                 }
1212
1213                 $status = self::isTagNameValid( $tag );
1214                 if ( !$status->isGood() ) {
1215                         return $status;
1216                 }
1217
1218                 // does the tag already exist?
1219                 $tagUsage = self::tagUsageStatistics();
1220                 if ( isset( $tagUsage[$tag] ) || in_array( $tag, self::listDefinedTags() ) ) {
1221                         return Status::newFatal( 'tags-create-already-exists', $tag );
1222                 }
1223
1224                 // check with hooks
1225                 $canCreateResult = Status::newGood();
1226                 Hooks::run( 'ChangeTagCanCreate', [ $tag, $user, &$canCreateResult ] );
1227                 return $canCreateResult;
1228         }
1229
1230         /**
1231          * Creates a tag by adding a row to the `valid_tag` table.
1232          * and/or add it to `change_tag_def` table.
1233          *
1234          * Extensions should NOT use this function; they can use the ListDefinedTags
1235          * hook instead.
1236          *
1237          * Includes a call to ChangeTag::canCreateTag(), so your code doesn't need to
1238          * do that.
1239          *
1240          * @param string $tag
1241          * @param string $reason
1242          * @param User $user Who to give credit for the action
1243          * @param bool $ignoreWarnings Can be used for API interaction, default false
1244          * @param array $logEntryTags Change tags to apply to the entry
1245          * that will be created in the tag management log
1246          * @return Status If successful, the Status contains the ID of the added log
1247          * entry as its value
1248          * @since 1.25
1249          */
1250         public static function createTagWithChecks( $tag, $reason, User $user,
1251                 $ignoreWarnings = false, array $logEntryTags = []
1252         ) {
1253                 // are we allowed to do this?
1254                 $result = self::canCreateTag( $tag, $user );
1255                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1256                         $result->value = null;
1257                         return $result;
1258                 }
1259
1260                 // do it!
1261                 self::defineTag( $tag );
1262
1263                 // log it
1264                 $logId = self::logTagManagementAction( 'create', $tag, $reason, $user,
1265                         null, $logEntryTags );
1266
1267                 return Status::newGood( $logId );
1268         }
1269
1270         /**
1271          * Permanently removes all traces of a tag from the DB. Good for removing
1272          * misspelt or temporary tags.
1273          *
1274          * This function should be directly called by maintenance scripts only, never
1275          * by user-facing code. See deleteTagWithChecks() for functionality that can
1276          * safely be exposed to users.
1277          *
1278          * @param string $tag Tag to remove
1279          * @return Status The returned status will be good unless a hook changed it
1280          * @since 1.25
1281          */
1282         public static function deleteTagEverywhere( $tag ) {
1283                 global $wgChangeTagsSchemaMigrationStage;
1284                 $dbw = wfGetDB( DB_MASTER );
1285                 $dbw->startAtomic( __METHOD__ );
1286
1287                 // delete from valid_tag and/or set ctd_user_defined = 0
1288                 self::undefineTag( $tag );
1289
1290                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_WRITE_BOTH ) {
1291                         $tagId = MediaWikiServices::getInstance()->getChangeTagDefStore()->getId( $tag );
1292                         $conditions = [ 'ct_tag_id' => $tagId ];
1293                 } else {
1294                         $conditions = [ 'ct_tag' => $tag ];
1295                 }
1296
1297                 // find out which revisions use this tag, so we can delete from tag_summary
1298                 $result = $dbw->select( 'change_tag',
1299                         [ 'ct_rc_id', 'ct_log_id', 'ct_rev_id' ],
1300                         $conditions,
1301                         __METHOD__ );
1302                 foreach ( $result as $row ) {
1303                         // remove the tag from the relevant row of tag_summary
1304                         $tagsToAdd = [];
1305                         $tagsToRemove = [ $tag ];
1306                         self::updateTagSummaryRow( $tagsToAdd, $tagsToRemove, $row->ct_rc_id,
1307                                 $row->ct_rev_id, $row->ct_log_id );
1308                 }
1309
1310                 // delete from change_tag
1311                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_WRITE_BOTH ) {
1312                         $tagId = MediaWikiServices::getInstance()->getChangeTagDefStore()->getId( $tag );
1313                         $dbw->delete( 'change_tag', [ 'ct_tag_id' => $tagId ], __METHOD__ );
1314                 } else {
1315                         $dbw->delete( 'change_tag', [ 'ct_tag' => $tag ], __METHOD__ );
1316                 }
1317
1318                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_OLD ) {
1319                         $dbw->delete( 'change_tag_def', [ 'ctd_name' => $tag ], __METHOD__ );
1320                 }
1321
1322                 $dbw->endAtomic( __METHOD__ );
1323
1324                 // give extensions a chance
1325                 $status = Status::newGood();
1326                 Hooks::run( 'ChangeTagAfterDelete', [ $tag, &$status ] );
1327                 // let's not allow error results, as the actual tag deletion succeeded
1328                 if ( !$status->isOK() ) {
1329                         wfDebug( 'ChangeTagAfterDelete error condition downgraded to warning' );
1330                         $status->setOK( true );
1331                 }
1332
1333                 // clear the memcache of defined tags
1334                 self::purgeTagCacheAll();
1335
1336                 return $status;
1337         }
1338
1339         /**
1340          * Is it OK to allow the user to delete this tag?
1341          *
1342          * @param string $tag Tag that you are interested in deleting
1343          * @param User|null $user User whose permission you wish to check, or null if
1344          * you don't care (e.g. maintenance scripts)
1345          * @return Status
1346          * @since 1.25
1347          */
1348         public static function canDeleteTag( $tag, User $user = null ) {
1349                 $tagUsage = self::tagUsageStatistics();
1350
1351                 if ( !is_null( $user ) ) {
1352                         if ( !$user->isAllowed( 'deletechangetags' ) ) {
1353                                 return Status::newFatal( 'tags-delete-no-permission' );
1354                         } elseif ( $user->isBlocked() ) {
1355                                 return Status::newFatal( 'tags-manage-blocked', $user->getName() );
1356                         }
1357                 }
1358
1359                 if ( !isset( $tagUsage[$tag] ) && !in_array( $tag, self::listDefinedTags() ) ) {
1360                         return Status::newFatal( 'tags-delete-not-found', $tag );
1361                 }
1362
1363                 if ( isset( $tagUsage[$tag] ) && $tagUsage[$tag] > self::MAX_DELETE_USES ) {
1364                         return Status::newFatal( 'tags-delete-too-many-uses', $tag, self::MAX_DELETE_USES );
1365                 }
1366
1367                 $softwareDefined = self::listSoftwareDefinedTags();
1368                 if ( in_array( $tag, $softwareDefined ) ) {
1369                         // extension-defined tags can't be deleted unless the extension
1370                         // specifically allows it
1371                         $status = Status::newFatal( 'tags-delete-not-allowed' );
1372                 } else {
1373                         // user-defined tags are deletable unless otherwise specified
1374                         $status = Status::newGood();
1375                 }
1376
1377                 Hooks::run( 'ChangeTagCanDelete', [ $tag, $user, &$status ] );
1378                 return $status;
1379         }
1380
1381         /**
1382          * Deletes a tag, checking whether it is allowed first, and adding a log entry
1383          * afterwards.
1384          *
1385          * Includes a call to ChangeTag::canDeleteTag(), so your code doesn't need to
1386          * do that.
1387          *
1388          * @param string $tag
1389          * @param string $reason
1390          * @param User $user Who to give credit for the action
1391          * @param bool $ignoreWarnings Can be used for API interaction, default false
1392          * @param array $logEntryTags Change tags to apply to the entry
1393          * that will be created in the tag management log
1394          * @return Status If successful, the Status contains the ID of the added log
1395          * entry as its value
1396          * @since 1.25
1397          */
1398         public static function deleteTagWithChecks( $tag, $reason, User $user,
1399                 $ignoreWarnings = false, array $logEntryTags = []
1400         ) {
1401                 // are we allowed to do this?
1402                 $result = self::canDeleteTag( $tag, $user );
1403                 if ( $ignoreWarnings ? !$result->isOK() : !$result->isGood() ) {
1404                         $result->value = null;
1405                         return $result;
1406                 }
1407
1408                 // store the tag usage statistics
1409                 $tagUsage = self::tagUsageStatistics();
1410                 $hitcount = $tagUsage[$tag] ?? 0;
1411
1412                 // do it!
1413                 $deleteResult = self::deleteTagEverywhere( $tag );
1414                 if ( !$deleteResult->isOK() ) {
1415                         return $deleteResult;
1416                 }
1417
1418                 // log it
1419                 $logId = self::logTagManagementAction( 'delete', $tag, $reason, $user,
1420                         $hitcount, $logEntryTags );
1421
1422                 $deleteResult->value = $logId;
1423                 return $deleteResult;
1424         }
1425
1426         /**
1427          * Lists those tags which core or extensions report as being "active".
1428          *
1429          * @return array
1430          * @since 1.25
1431          */
1432         public static function listSoftwareActivatedTags() {
1433                 // core active tags
1434                 $tags = self::getSoftwareTags();
1435                 if ( !Hooks::isRegistered( 'ChangeTagsListActive' ) ) {
1436                         return $tags;
1437                 }
1438                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1439                 return $cache->getWithSetCallback(
1440                         $cache->makeKey( 'active-tags' ),
1441                         WANObjectCache::TTL_MINUTE * 5,
1442                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1443                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1444
1445                                 // Ask extensions which tags they consider active
1446                                 Hooks::run( 'ChangeTagsListActive', [ &$tags ] );
1447                                 return $tags;
1448                         },
1449                         [
1450                                 'checkKeys' => [ $cache->makeKey( 'active-tags' ) ],
1451                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1452                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1453                         ]
1454                 );
1455         }
1456
1457         /**
1458          * Basically lists defined tags which count even if they aren't applied to anything.
1459          * It returns a union of the results of listExplicitlyDefinedTags()
1460          *
1461          * @return string[] Array of strings: tags
1462          */
1463         public static function listDefinedTags() {
1464                 $tags1 = self::listExplicitlyDefinedTags();
1465                 $tags2 = self::listSoftwareDefinedTags();
1466                 return array_values( array_unique( array_merge( $tags1, $tags2 ) ) );
1467         }
1468
1469         /**
1470          * Lists tags explicitly defined in the `valid_tag` table of the database.
1471          * Tags in table 'change_tag' which are not in table 'valid_tag' are not
1472          * included. In case of new backend loads the data from `change_tag_def` table.
1473          *
1474          * Tries memcached first.
1475          *
1476          * @return string[] Array of strings: tags
1477          * @since 1.25
1478          */
1479         public static function listExplicitlyDefinedTags() {
1480                 $fname = __METHOD__;
1481
1482                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1483                 return $cache->getWithSetCallback(
1484                         $cache->makeKey( 'valid-tags-db' ),
1485                         WANObjectCache::TTL_MINUTE * 5,
1486                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1487                                 global $wgChangeTagsSchemaMigrationStage;
1488                                 $dbr = wfGetDB( DB_REPLICA );
1489
1490                                 $setOpts += Database::getCacheSetOptions( $dbr );
1491
1492                                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_WRITE_BOTH ) {
1493                                         $tags = self::listExplicitlyDefinedTagsNewBackend();
1494                                 } else {
1495                                         $tags = $dbr->selectFieldValues( 'valid_tag', 'vt_tag', [], $fname );
1496                                 }
1497
1498                                 return array_filter( array_unique( $tags ) );
1499                         },
1500                         [
1501                                 'checkKeys' => [ $cache->makeKey( 'valid-tags-db' ) ],
1502                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1503                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1504                         ]
1505                 );
1506         }
1507
1508         /**
1509          * Lists tags explicitly user defined tags. When ctd_user_defined is true.
1510          *
1511          * @return string[] Array of strings: tags
1512          * @since 1.25
1513          */
1514         private static function listExplicitlyDefinedTagsNewBackend() {
1515                 $dbr = wfGetDB( DB_REPLICA );
1516                 return $dbr->selectFieldValues(
1517                         'change_tag_def',
1518                         'ctd_name',
1519                         [ 'ctd_user_defined' => 1 ],
1520                         __METHOD__
1521                 );
1522         }
1523
1524         /**
1525          * Lists tags defined by core or extensions using the ListDefinedTags hook.
1526          * Extensions need only define those tags they deem to be in active use.
1527          *
1528          * Tries memcached first.
1529          *
1530          * @return string[] Array of strings: tags
1531          * @since 1.25
1532          */
1533         public static function listSoftwareDefinedTags() {
1534                 // core defined tags
1535                 $tags = self::getSoftwareTags( true );
1536                 if ( !Hooks::isRegistered( 'ListDefinedTags' ) ) {
1537                         return $tags;
1538                 }
1539                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1540                 return $cache->getWithSetCallback(
1541                         $cache->makeKey( 'valid-tags-hook' ),
1542                         WANObjectCache::TTL_MINUTE * 5,
1543                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $tags ) {
1544                                 $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
1545
1546                                 Hooks::run( 'ListDefinedTags', [ &$tags ] );
1547                                 return array_filter( array_unique( $tags ) );
1548                         },
1549                         [
1550                                 'checkKeys' => [ $cache->makeKey( 'valid-tags-hook' ) ],
1551                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1552                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1553                         ]
1554                 );
1555         }
1556
1557         /**
1558          * Invalidates the short-term cache of defined tags used by the
1559          * list*DefinedTags functions, as well as the tag statistics cache.
1560          * @since 1.25
1561          */
1562         public static function purgeTagCacheAll() {
1563                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1564
1565                 $cache->touchCheckKey( $cache->makeKey( 'active-tags' ) );
1566                 $cache->touchCheckKey( $cache->makeKey( 'valid-tags-db' ) );
1567                 $cache->touchCheckKey( $cache->makeKey( 'valid-tags-hook' ) );
1568
1569                 self::purgeTagUsageCache();
1570         }
1571
1572         /**
1573          * Invalidates the tag statistics cache only.
1574          * @since 1.25
1575          */
1576         public static function purgeTagUsageCache() {
1577                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1578
1579                 $cache->touchCheckKey( $cache->makeKey( 'change-tag-statistics' ) );
1580         }
1581
1582         /**
1583          * Returns a map of any tags used on the wiki to number of edits
1584          * tagged with them, ordered descending by the hitcount.
1585          * This does not include tags defined somewhere that have never been applied.
1586          *
1587          * Keeps a short-term cache in memory, so calling this multiple times in the
1588          * same request should be fine.
1589          *
1590          * @return array Array of string => int
1591          */
1592         public static function tagUsageStatistics() {
1593                 global $wgChangeTagsSchemaMigrationStage;
1594                 if ( $wgChangeTagsSchemaMigrationStage > MIGRATION_WRITE_BOTH ) {
1595                         return self::newTagUsageStatistics();
1596                 }
1597
1598                 $fname = __METHOD__;
1599                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1600                 return $cache->getWithSetCallback(
1601                         $cache->makeKey( 'change-tag-statistics' ),
1602                         WANObjectCache::TTL_MINUTE * 5,
1603                         function ( $oldValue, &$ttl, array &$setOpts ) use ( $fname ) {
1604                                 $dbr = wfGetDB( DB_REPLICA, 'vslow' );
1605
1606                                 $setOpts += Database::getCacheSetOptions( $dbr );
1607
1608                                 $res = $dbr->select(
1609                                         'change_tag',
1610                                         [ 'ct_tag', 'hitcount' => 'count(*)' ],
1611                                         [],
1612                                         $fname,
1613                                         [ 'GROUP BY' => 'ct_tag', 'ORDER BY' => 'hitcount DESC' ]
1614                                 );
1615
1616                                 $out = [];
1617                                 foreach ( $res as $row ) {
1618                                         $out[$row->ct_tag] = $row->hitcount;
1619                                 }
1620
1621                                 return $out;
1622                         },
1623                         [
1624                                 'checkKeys' => [ $cache->makeKey( 'change-tag-statistics' ) ],
1625                                 'lockTSE' => WANObjectCache::TTL_MINUTE * 5,
1626                                 'pcTTL' => WANObjectCache::TTL_PROC_LONG
1627                         ]
1628                 );
1629         }
1630
1631         /**
1632          * Same self::tagUsageStatistics() but uses change_tag_def.
1633          *
1634          * @return array Array of string => int
1635          */
1636         private static function newTagUsageStatistics() {
1637                 $dbr = wfGetDB( DB_REPLICA );
1638                 $res = $dbr->select(
1639                         'change_tag_def',
1640                         [ 'ctd_name', 'ctd_count' ],
1641                         [],
1642                         __METHOD__,
1643                         [ 'ORDER BY' => 'ctd_count DESC' ]
1644                 );
1645
1646                 $out = [];
1647                 foreach ( $res as $row ) {
1648                         $out[$row->ctd_name] = $row->ctd_count;
1649                 }
1650
1651                 return $out;
1652         }
1653
1654         /**
1655          * Indicate whether change tag editing UI is relevant
1656          *
1657          * Returns true if the user has the necessary right and there are any
1658          * editable tags defined.
1659          *
1660          * This intentionally doesn't check "any addable || any deletable", because
1661          * it seems like it would be more confusing than useful if the checkboxes
1662          * suddenly showed up because some abuse filter stopped defining a tag and
1663          * then suddenly disappeared when someone deleted all uses of that tag.
1664          *
1665          * @param User $user
1666          * @return bool
1667          */
1668         public static function showTagEditingUI( User $user ) {
1669                 return $user->isAllowed( 'changetags' ) && (bool)self::listExplicitlyDefinedTags();
1670         }
1671 }