ChangesListSpecialPage.php

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<?php
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MediaWikiServices;
use Wikimedia\Rdbms\DBQueryTimeoutError;
use Wikimedia\Rdbms\IResultWrapper;
use Wikimedia\Rdbms\FakeResultWrapper;
use Wikimedia\Rdbms\IDatabase;

abstract class ChangesListSpecialPage extends SpecialPage {
    const TAG_DESC_CHARACTER_LIMIT = 120;

    protected static $savedQueriesPreferenceName;

    protected static $daysPreferenceName;

    protected static $limitPreferenceName;

    protected static $collapsedPreferenceName;

    protected $rcSubpage;

    protected $rcOptions;

    // Order of both groups and filters is significant; first is top-most priority,
    // descending from there.
    // 'showHideSuffix' is a shortcut to and avoid spelling out
    // details specific to subclasses here.
    private $filterGroupDefinitions;

    // Same format as filterGroupDefinitions, but for a single group (reviewStatus)
    // that is registered conditionally.
    private $legacyReviewStatusFilterGroupDefinition;

    // Single filter group registered conditionally
    private $reviewStatusFilterGroupDefinition;

    // Single filter group registered conditionally
    private $hideCategorizationFilterDefinition;

    protected $filterGroups = [];

    public function __construct( $name, $restriction ) {
        parent::__construct( $name, $restriction );

        $nonRevisionTypes = [ RC_LOG ];
        Hooks::run( 'SpecialWatchlistGetNonRevisionTypes', [ &$nonRevisionTypes ] );

        $this->filterGroupDefinitions = [
            [
                'name' => 'registration',
                'title' => 'rcfilters-filtergroup-registration',
                'class' => ChangesListBooleanFilterGroup::class,
                'filters' => [
                    [
                        'name' => 'hideliu',
                        // rcshowhideliu-show, rcshowhideliu-hide,
                        // wlshowhideliu
                        'showHideSuffix' => 'showhideliu',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $actorMigration = ActorMigration::newMigration();
                            $actorQuery = $actorMigration->getJoin( 'rc_user' );
                            $tables += $actorQuery['tables'];
                            $join_conds += $actorQuery['joins'];
                            $conds[] = $actorMigration->isAnon( $actorQuery['fields']['rc_user'] );
                        },
                        'isReplacedInStructuredUi' => true,

                    ],
                    [
                        'name' => 'hideanons',
                        // rcshowhideanons-show, rcshowhideanons-hide,
                        // wlshowhideanons
                        'showHideSuffix' => 'showhideanons',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $actorMigration = ActorMigration::newMigration();
                            $actorQuery = $actorMigration->getJoin( 'rc_user' );
                            $tables += $actorQuery['tables'];
                            $join_conds += $actorQuery['joins'];
                            $conds[] = $actorMigration->isNotAnon( $actorQuery['fields']['rc_user'] );
                        },
                        'isReplacedInStructuredUi' => true,
                    ]
                ],
            ],

            [
                'name' => 'userExpLevel',
                'title' => 'rcfilters-filtergroup-user-experience-level',
                'class' => ChangesListStringOptionsFilterGroup::class,
                'isFullCoverage' => true,
                'filters' => [
                    [
                        'name' => 'unregistered',
                        'label' => 'rcfilters-filter-user-experience-level-unregistered-label',
                        'description' => 'rcfilters-filter-user-experience-level-unregistered-description',
                        'cssClassSuffix' => 'user-unregistered',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return !$rc->getAttribute( 'rc_user' );
                        }
                    ],
                    [
                        'name' => 'registered',
                        'label' => 'rcfilters-filter-user-experience-level-registered-label',
                        'description' => 'rcfilters-filter-user-experience-level-registered-description',
                        'cssClassSuffix' => 'user-registered',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_user' );
                        }
                    ],
                    [
                        'name' => 'newcomer',
                        'label' => 'rcfilters-filter-user-experience-level-newcomer-label',
                        'description' => 'rcfilters-filter-user-experience-level-newcomer-description',
                        'cssClassSuffix' => 'user-newcomer',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            $performer = $rc->getPerformer();
                            return $performer && $performer->isLoggedIn() &&
                                $performer->getExperienceLevel() === 'newcomer';
                        }
                    ],
                    [
                        'name' => 'learner',
                        'label' => 'rcfilters-filter-user-experience-level-learner-label',
                        'description' => 'rcfilters-filter-user-experience-level-learner-description',
                        'cssClassSuffix' => 'user-learner',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            $performer = $rc->getPerformer();
                            return $performer && $performer->isLoggedIn() &&
                                $performer->getExperienceLevel() === 'learner';
                        },
                    ],
                    [
                        'name' => 'experienced',
                        'label' => 'rcfilters-filter-user-experience-level-experienced-label',
                        'description' => 'rcfilters-filter-user-experience-level-experienced-description',
                        'cssClassSuffix' => 'user-experienced',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            $performer = $rc->getPerformer();
                            return $performer && $performer->isLoggedIn() &&
                                $performer->getExperienceLevel() === 'experienced';
                        },
                    ]
                ],
                'default' => ChangesListStringOptionsFilterGroup::NONE,
                'queryCallable' => [ $this, 'filterOnUserExperienceLevel' ],
            ],

            [
                'name' => 'authorship',
                'title' => 'rcfilters-filtergroup-authorship',
                'class' => ChangesListBooleanFilterGroup::class,
                'filters' => [
                    [
                        'name' => 'hidemyself',
                        'label' => 'rcfilters-filter-editsbyself-label',
                        'description' => 'rcfilters-filter-editsbyself-description',
                        // rcshowhidemine-show, rcshowhidemine-hide,
                        // wlshowhidemine
                        'showHideSuffix' => 'showhidemine',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $actorQuery = ActorMigration::newMigration()->getWhere( $dbr, 'rc_user', $ctx->getUser() );
                            $tables += $actorQuery['tables'];
                            $join_conds += $actorQuery['joins'];
                            $conds[] = 'NOT(' . $actorQuery['conds'] . ')';
                        },
                        'cssClassSuffix' => 'self',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $ctx->getUser()->equals( $rc->getPerformer() );
                        },
                    ],
                    [
                        'name' => 'hidebyothers',
                        'label' => 'rcfilters-filter-editsbyother-label',
                        'description' => 'rcfilters-filter-editsbyother-description',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $actorQuery = ActorMigration::newMigration()
                                ->getWhere( $dbr, 'rc_user', $ctx->getUser(), false );
                            $tables += $actorQuery['tables'];
                            $join_conds += $actorQuery['joins'];
                            $conds[] = $actorQuery['conds'];
                        },
                        'cssClassSuffix' => 'others',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return !$ctx->getUser()->equals( $rc->getPerformer() );
                        },
                    ]
                ]
            ],

            [
                'name' => 'automated',
                'title' => 'rcfilters-filtergroup-automated',
                'class' => ChangesListBooleanFilterGroup::class,
                'filters' => [
                    [
                        'name' => 'hidebots',
                        'label' => 'rcfilters-filter-bots-label',
                        'description' => 'rcfilters-filter-bots-description',
                        // rcshowhidebots-show, rcshowhidebots-hide,
                        // wlshowhidebots
                        'showHideSuffix' => 'showhidebots',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $conds['rc_bot'] = 0;
                        },
                        'cssClassSuffix' => 'bot',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_bot' );
                        },
                    ],
                    [
                        'name' => 'hidehumans',
                        'label' => 'rcfilters-filter-humans-label',
                        'description' => 'rcfilters-filter-humans-description',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $conds['rc_bot'] = 1;
                        },
                        'cssClassSuffix' => 'human',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return !$rc->getAttribute( 'rc_bot' );
                        },
                    ]
                ]
            ],

            // significance (conditional)

            [
                'name' => 'significance',
                'title' => 'rcfilters-filtergroup-significance',
                'class' => ChangesListBooleanFilterGroup::class,
                'priority' => -6,
                'filters' => [
                    [
                        'name' => 'hideminor',
                        'label' => 'rcfilters-filter-minor-label',
                        'description' => 'rcfilters-filter-minor-description',
                        // rcshowhideminor-show, rcshowhideminor-hide,
                        // wlshowhideminor
                        'showHideSuffix' => 'showhideminor',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $conds[] = 'rc_minor = 0';
                        },
                        'cssClassSuffix' => 'minor',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_minor' );
                        }
                    ],
                    [
                        'name' => 'hidemajor',
                        'label' => 'rcfilters-filter-major-label',
                        'description' => 'rcfilters-filter-major-description',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $conds[] = 'rc_minor = 1';
                        },
                        'cssClassSuffix' => 'major',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return !$rc->getAttribute( 'rc_minor' );
                        }
                    ]
                ]
            ],

            [
                'name' => 'lastRevision',
                'title' => 'rcfilters-filtergroup-lastrevision',
                'class' => ChangesListBooleanFilterGroup::class,
                'priority' => -7,
                'filters' => [
                    [
                        'name' => 'hidelastrevision',
                        'label' => 'rcfilters-filter-lastrevision-label',
                        'description' => 'rcfilters-filter-lastrevision-description',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds ) use ( $nonRevisionTypes ) {
                            $conds[] = $dbr->makeList(
                                [
                                    'rc_this_oldid <> page_latest',
                                    'rc_type' => $nonRevisionTypes,
                                ],
                                LIST_OR
                            );
                        },
                        'cssClassSuffix' => 'last',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_this_oldid' ) === $rc->getAttribute( 'page_latest' );
                        }
                    ],
                    [
                        'name' => 'hidepreviousrevisions',
                        'label' => 'rcfilters-filter-previousrevision-label',
                        'description' => 'rcfilters-filter-previousrevision-description',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds ) use ( $nonRevisionTypes ) {
                            $conds[] = $dbr->makeList(
                                [
                                    'rc_this_oldid = page_latest',
                                    'rc_type' => $nonRevisionTypes,
                                ],
                                LIST_OR
                            );
                        },
                        'cssClassSuffix' => 'previous',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_this_oldid' ) !== $rc->getAttribute( 'page_latest' );
                        }
                    ]
                ]
            ],

            // With extensions, there can be change types that will not be hidden by any of these.
            [
                'name' => 'changeType',
                'title' => 'rcfilters-filtergroup-changetype',
                'class' => ChangesListBooleanFilterGroup::class,
                'priority' => -8,
                'filters' => [
                    [
                        'name' => 'hidepageedits',
                        'label' => 'rcfilters-filter-pageedits-label',
                        'description' => 'rcfilters-filter-pageedits-description',
                        'default' => false,
                        'priority' => -2,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $conds[] = 'rc_type != ' . $dbr->addQuotes( RC_EDIT );
                        },
                        'cssClassSuffix' => 'src-mw-edit',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_source' ) === RecentChange::SRC_EDIT;
                        },
                    ],
                    [
                        'name' => 'hidenewpages',
                        'label' => 'rcfilters-filter-newpages-label',
                        'description' => 'rcfilters-filter-newpages-description',
                        'default' => false,
                        'priority' => -3,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $conds[] = 'rc_type != ' . $dbr->addQuotes( RC_NEW );
                        },
                        'cssClassSuffix' => 'src-mw-new',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_source' ) === RecentChange::SRC_NEW;
                        },
                    ],

                    // hidecategorization

                    [
                        'name' => 'hidelog',
                        'label' => 'rcfilters-filter-logactions-label',
                        'description' => 'rcfilters-filter-logactions-description',
                        'default' => false,
                        'priority' => -5,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $conds[] = 'rc_type != ' . $dbr->addQuotes( RC_LOG );
                        },
                        'cssClassSuffix' => 'src-mw-log',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_source' ) === RecentChange::SRC_LOG;
                        }
                    ],
                ],
            ],

        ];

        $this->legacyReviewStatusFilterGroupDefinition = [
            [
                'name' => 'legacyReviewStatus',
                'title' => 'rcfilters-filtergroup-reviewstatus',
                'class' => ChangesListBooleanFilterGroup::class,
                'filters' => [
                    [
                        'name' => 'hidepatrolled',
                        // rcshowhidepatr-show, rcshowhidepatr-hide
                        // wlshowhidepatr
                        'showHideSuffix' => 'showhidepatr',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $conds['rc_patrolled'] = RecentChange::PRC_UNPATROLLED;
                        },
                        'isReplacedInStructuredUi' => true,
                    ],
                    [
                        'name' => 'hideunpatrolled',
                        'default' => false,
                        'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                            &$query_options, &$join_conds
                        ) {
                            $conds[] = 'rc_patrolled != ' . RecentChange::PRC_UNPATROLLED;
                        },
                        'isReplacedInStructuredUi' => true,
                    ],
                ],
            ]
        ];

        $this->reviewStatusFilterGroupDefinition = [
            [
                'name' => 'reviewStatus',
                'title' => 'rcfilters-filtergroup-reviewstatus',
                'class' => ChangesListStringOptionsFilterGroup::class,
                'isFullCoverage' => true,
                'priority' => -5,
                'filters' => [
                    [
                        'name' => 'unpatrolled',
                        'label' => 'rcfilters-filter-reviewstatus-unpatrolled-label',
                        'description' => 'rcfilters-filter-reviewstatus-unpatrolled-description',
                        'cssClassSuffix' => 'reviewstatus-unpatrolled',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_patrolled' ) == RecentChange::PRC_UNPATROLLED;
                        },
                    ],
                    [
                        'name' => 'manual',
                        'label' => 'rcfilters-filter-reviewstatus-manual-label',
                        'description' => 'rcfilters-filter-reviewstatus-manual-description',
                        'cssClassSuffix' => 'reviewstatus-manual',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_patrolled' ) == RecentChange::PRC_PATROLLED;
                        },
                    ],
                    [
                        'name' => 'auto',
                        'label' => 'rcfilters-filter-reviewstatus-auto-label',
                        'description' => 'rcfilters-filter-reviewstatus-auto-description',
                        'cssClassSuffix' => 'reviewstatus-auto',
                        'isRowApplicableCallable' => function ( $ctx, $rc ) {
                            return $rc->getAttribute( 'rc_patrolled' ) == RecentChange::PRC_AUTOPATROLLED;
                        },
                    ],
                ],
                'default' => ChangesListStringOptionsFilterGroup::NONE,
                'queryCallable' => function ( $specialPageClassName, $ctx, $dbr,
                    &$tables, &$fields, &$conds, &$query_options, &$join_conds, $selected
                ) {
                    if ( $selected === [] ) {
                        return;
                    }
                    $rcPatrolledValues = [
                        'unpatrolled' => RecentChange::PRC_UNPATROLLED,
                        'manual' => RecentChange::PRC_PATROLLED,
                        'auto' => RecentChange::PRC_AUTOPATROLLED,
                    ];
                    // e.g. rc_patrolled IN (0, 2)
                    $conds['rc_patrolled'] = array_map( function ( $s ) use ( $rcPatrolledValues ) {
                        return $rcPatrolledValues[ $s ];
                    }, $selected );
                }
            ]
        ];

        $this->hideCategorizationFilterDefinition = [
            'name' => 'hidecategorization',
            'label' => 'rcfilters-filter-categorization-label',
            'description' => 'rcfilters-filter-categorization-description',
            // rcshowhidecategorization-show, rcshowhidecategorization-hide.
            // wlshowhidecategorization
            'showHideSuffix' => 'showhidecategorization',
            'default' => false,
            'priority' => -4,
            'queryCallable' => function ( $specialClassName, $ctx, $dbr, &$tables, &$fields, &$conds,
                &$query_options, &$join_conds
            ) {
                $conds[] = 'rc_type != ' . $dbr->addQuotes( RC_CATEGORIZE );
            },
            'cssClassSuffix' => 'src-mw-categorize',
            'isRowApplicableCallable' => function ( $ctx, $rc ) {
                return $rc->getAttribute( 'rc_source' ) === RecentChange::SRC_CATEGORIZE;
            },
        ];
    }

    protected function areFiltersInConflict() {
        $opts = $this->getOptions();
        foreach ( $this->getFilterGroups() as $group ) {
            if ( $group->getConflictingGroups() ) {
                wfLogWarning(
                    $group->getName() .
                    " specifies conflicts with other groups but these are not supported yet."
                );
            }

            foreach ( $group->getConflictingFilters() as $conflictingFilter ) {
                if ( $conflictingFilter->activelyInConflictWithGroup( $group, $opts ) ) {
                    return true;
                }
            }

            foreach ( $group->getFilters() as $filter ) {
                foreach ( $filter->getConflictingFilters() as $conflictingFilter ) {
                    if (
                        $conflictingFilter->activelyInConflictWithFilter( $filter, $opts ) &&
                        $filter->activelyInConflictWithFilter( $conflictingFilter, $opts )
                    ) {
                        return true;
                    }
                }

            }

        }

        return false;
    }

    public function execute( $subpage ) {
        $this->rcSubpage = $subpage;

        $this->considerActionsForDefaultSavedQuery( $subpage );

        $opts = $this->getOptions();
        try {
            $rows = $this->getRows();
            if ( $rows === false ) {
                $rows = new FakeResultWrapper( [] );
            }

            // Used by Structured UI app to get results without MW chrome
            if ( $this->getRequest()->getVal( 'action' ) === 'render' ) {
                $this->getOutput()->setArticleBodyOnly( true );
            }

            // Used by "live update" and "view newest" to check
            // if there's new changes with minimal data transfer
            if ( $this->getRequest()->getBool( 'peek' ) ) {
                $code = $rows->numRows() > 0 ? 200 : 204;
                $this->getOutput()->setStatusCode( $code );

                if ( $this->getUser()->isAnon() !==
                    $this->getRequest()->getFuzzyBool( 'isAnon' )
                ) {
                    $this->getOutput()->setStatusCode( 205 );
                }

                return;
            }

            $batch = new LinkBatch;
            foreach ( $rows as $row ) {
                $batch->add( NS_USER, $row->rc_user_text );
                $batch->add( NS_USER_TALK, $row->rc_user_text );
                $batch->add( $row->rc_namespace, $row->rc_title );
                if ( $row->rc_source === RecentChange::SRC_LOG ) {
                    $formatter = LogFormatter::newFromRow( $row );
                    foreach ( $formatter->getPreloadTitles() as $title ) {
                        $batch->addObj( $title );
                    }
                }
            }
            $batch->execute();

            $this->setHeaders();
            $this->outputHeader();
            $this->addModules();
            $this->webOutput( $rows, $opts );

            $rows->free();
        } catch ( DBQueryTimeoutError $timeoutException ) {
            MWExceptionHandler::logException( $timeoutException );

            $this->setHeaders();
            $this->outputHeader();
            $this->addModules();

            $this->getOutput()->setStatusCode( 500 );
            $this->webOutputHeader( 0, $opts );
            $this->outputTimeout();
        }

        if ( $this->getConfig()->get( 'EnableWANCacheReaper' ) ) {
            // Clean up any bad page entries for titles showing up in RC
            DeferredUpdates::addUpdate( new WANCacheReapUpdate(
                $this->getDB(),
                LoggerFactory::getInstance( 'objectcache' )
            ) );
        }

        $this->includeRcFiltersApp();
    }

    protected function considerActionsForDefaultSavedQuery( $subpage ) {
        if ( !$this->isStructuredFilterUiEnabled() || $this->including() ) {
            return;
        }

        $knownParams = $this->getRequest()->getValues(
            ...array_keys( $this->getOptions()->getAllValues() )
        );

        // HACK: Temporarily until we can properly define "sticky" filters and parameters,
        // we need to exclude several parameters we know should not be counted towards preventing
        // the loading of defaults.
        $excludedParams = [ 'limit' => '', 'days' => '', 'enhanced' => '', 'from' => '' ];
        $knownParams = array_diff_key( $knownParams, $excludedParams );

        if (
            // If there are NO known parameters in the URL request
            // (that are not excluded) then we need to check into loading
            // the default saved query
            count( $knownParams ) === 0
        ) {
            // Get the saved queries data and parse it
            $savedQueries = FormatJson::decode(
                $this->getUser()->getOption( static::$savedQueriesPreferenceName ),
                true
            );

            if ( $savedQueries && isset( $savedQueries[ 'default' ] ) ) {
                // Only load queries that are 'version' 2, since those
                // have parameter representation
                if ( isset( $savedQueries[ 'version' ] ) && $savedQueries[ 'version' ] === '2' ) {
                    $savedQueryDefaultID = $savedQueries[ 'default' ];
                    $defaultQuery = $savedQueries[ 'queries' ][ $savedQueryDefaultID ][ 'data' ];

                    // Build the entire parameter list
                    $query = array_merge(
                        $defaultQuery[ 'params' ],
                        $defaultQuery[ 'highlights' ],
                        [
                            'urlversion' => '2',
                        ]
                    );
                    // Add to the query any parameters that we may have ignored before
                    // but are still valid and requested in the URL
                    $query = array_merge( $this->getRequest()->getValues(), $query );
                    unset( $query[ 'title' ] );
                    $this->getOutput()->redirect( $this->getPageTitle( $subpage )->getCanonicalURL( $query ) );
                } else {
                    // There's a default, but the version is not 2, and the server can't
                    // actually recognize the query itself. This happens if it is before
                    // the conversion, so we need to tell the UI to reload saved query as
                    // it does the conversion to version 2
                    $this->getOutput()->addJsConfigVars(
                        'wgStructuredChangeFiltersDefaultSavedQueryExists',
                        true
                    );

                    // Add the class that tells the frontend it is still loading
                    // another query
                    $this->getOutput()->addBodyClasses( 'mw-rcfilters-ui-loading' );
                }
            }
        }
    }

    protected function getLinkDays() {
        $linkDays = $this->getConfig()->get( 'RCLinkDays' );
        $filterByAge = $this->getConfig()->get( 'RCFilterByAge' );
        $maxAge = $this->getConfig()->get( 'RCMaxAge' );
        if ( $filterByAge ) {
            // Trim it to only links which are within $wgRCMaxAge.
            // Note that we allow one link higher than the max for things like
            // "age 56 days" being accessible through the "60 days" link.
            sort( $linkDays );

            $maxAgeDays = $maxAge / ( 3600 * 24 );
            foreach ( $linkDays as $i => $days ) {
                if ( $days >= $maxAgeDays ) {
                    array_splice( $linkDays, $i + 1 );
                    break;
                }
            }
        }

        return $linkDays;
    }

    protected function includeRcFiltersApp() {
        $out = $this->getOutput();
        if ( $this->isStructuredFilterUiEnabled() && !$this->including() ) {
            $jsData = $this->getStructuredFilterJsData();
            $messages = [];
            foreach ( $jsData['messageKeys'] as $key ) {
                $messages[$key] = $this->msg( $key )->plain();
            }

            $out->addBodyClasses( 'mw-rcfilters-enabled' );
            $collapsed = $this->getUser()->getBoolOption( static::$collapsedPreferenceName );
            if ( $collapsed ) {
                $out->addBodyClasses( 'mw-rcfilters-collapsed' );
            }

            // These config and message exports should be moved into a ResourceLoader data module (T201574)
            $out->addJsConfigVars( 'wgStructuredChangeFilters', $jsData['groups'] );
            $out->addJsConfigVars( 'wgStructuredChangeFiltersMessages', $messages );
            $out->addJsConfigVars( 'wgStructuredChangeFiltersCollapsedState', $collapsed );

            $out->addJsConfigVars(
                'StructuredChangeFiltersDisplayConfig',
                [
                    'maxDays' => (int)$this->getConfig()->get( 'RCMaxAge' ) / ( 24 * 3600 ), // Translate to days
                    'limitArray' => $this->getConfig()->get( 'RCLinkLimits' ),
                    'limitDefault' => $this->getDefaultLimit(),
                    'daysArray' => $this->getLinkDays(),
                    'daysDefault' => $this->getDefaultDays(),
                ]
            );

            $out->addJsConfigVars(
                'wgStructuredChangeFiltersSavedQueriesPreferenceName',
                static::$savedQueriesPreferenceName
            );
            $out->addJsConfigVars(
                'wgStructuredChangeFiltersLimitPreferenceName',
                static::$limitPreferenceName
            );
            $out->addJsConfigVars(
                'wgStructuredChangeFiltersDaysPreferenceName',
                static::$daysPreferenceName
            );
            $out->addJsConfigVars(
                'wgStructuredChangeFiltersCollapsedPreferenceName',
                static::$collapsedPreferenceName
            );
        } else {
            $out->addBodyClasses( 'mw-rcfilters-disabled' );
        }
    }

    public static function getRcFiltersConfigSummary( ResourceLoaderContext $context ) {
        return [
            // Reduce version computation by avoiding Message parsing
            'RCFiltersChangeTags' => self::getChangeTagListSummary( $context ),
            'StructuredChangeFiltersEditWatchlistUrl' =>
                SpecialPage::getTitleFor( 'EditWatchlist' )->getLocalURL()
        ];
    }

    public static function getRcFiltersConfigVars( ResourceLoaderContext $context ) {
        return [
            'RCFiltersChangeTags' => self::getChangeTagList( $context ),
            'StructuredChangeFiltersEditWatchlistUrl' =>
                SpecialPage::getTitleFor( 'EditWatchlist' )->getLocalURL()
        ];
    }

    protected static function getChangeTagListSummary( ResourceLoaderContext $context ) {
        $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
        return $cache->getWithSetCallback(
            $cache->makeKey( 'ChangesListSpecialPage-changeTagListSummary', $context->getLanguage() ),
            WANObjectCache::TTL_DAY,
            function ( $oldValue, &$ttl, array &$setOpts ) use ( $context ) {
                $explicitlyDefinedTags = array_fill_keys( ChangeTags::listExplicitlyDefinedTags(), 0 );
                $softwareActivatedTags = array_fill_keys( ChangeTags::listSoftwareActivatedTags(), 0 );

                $tagStats = ChangeTags::tagUsageStatistics();
                $tagHitCounts = array_merge( $explicitlyDefinedTags, $softwareActivatedTags, $tagStats );

                $result = [];
                foreach ( $tagHitCounts as $tagName => $hits ) {
                    if (
                        (
                            // Only get active tags
                            isset( $explicitlyDefinedTags[ $tagName ] ) ||
                            isset( $softwareActivatedTags[ $tagName ] )
                        ) &&
                        // Only get tags with more than 0 hits
                        $hits > 0
                    ) {
                        $labelMsg = ChangeTags::tagShortDescriptionMessage( $tagName, $context );
                        if ( $labelMsg === false ) {
                            // Tag is hidden, skip it
                            continue;
                        }
                        $descriptionMsg = ChangeTags::tagLongDescriptionMessage( $tagName, $context );
                        $result[] = [
                            'name' => $tagName,
                            'labelMsg' => $labelMsg,
                            'label' => $labelMsg->plain(),
                            'descriptionMsg' => $descriptionMsg,
                            'description' => $descriptionMsg ? $descriptionMsg->plain() : '',
                            'cssClass' => Sanitizer::escapeClass( 'mw-tag-' . $tagName ),
                            'hits' => $hits,
                        ];
                    }
                }
                return $result;
            }
        );
    }

    protected static function getChangeTagList( ResourceLoaderContext $context ) {
        $tags = self::getChangeTagListSummary( $context );
        $language = Language::factory( $context->getLanguage() );
        foreach ( $tags as &$tagInfo ) {
            $tagInfo['label'] = Sanitizer::stripAllTags( $tagInfo['labelMsg']->parse() );
            $tagInfo['description'] = $tagInfo['descriptionMsg'] ?
                $language->truncateForVisual(
                    Sanitizer::stripAllTags( $tagInfo['descriptionMsg']->parse() ),
                    self::TAG_DESC_CHARACTER_LIMIT
                ) :
                '';
            unset( $tagInfo['labelMsg'] );
            unset( $tagInfo['descriptionMsg'] );
        }

        // Instead of sorting by hit count (disabled for now), sort by display name
        usort( $tags, function ( $a, $b ) {
            return strcasecmp( $a['label'], $b['label'] );
        } );
        return $tags;
    }

    protected function outputNoResults() {
        $this->getOutput()->addHTML(
            '<div class="mw-changeslist-empty">' .
            $this->msg( 'recentchanges-noresult' )->parse() .
            '</div>'
        );
    }

    protected function outputTimeout() {
        $this->getOutput()->addHTML(
            '<div class="mw-changeslist-empty mw-changeslist-timeout">' .
            $this->msg( 'recentchanges-timeout' )->parse() .
            '</div>'
        );
    }

    public function getRows() {
        $opts = $this->getOptions();

        $tables = [];
        $fields = [];
        $conds = [];
        $query_options = [];
        $join_conds = [];
        $this->buildQuery( $tables, $fields, $conds, $query_options, $join_conds, $opts );

        return $this->doMainQuery( $tables, $fields, $conds, $query_options, $join_conds, $opts );
    }

    public function getOptions() {
        if ( $this->rcOptions === null ) {
            $this->rcOptions = $this->setup( $this->rcSubpage );
        }

        return $this->rcOptions;
    }

    protected function registerFilters() {
        $this->registerFiltersFromDefinitions( $this->filterGroupDefinitions );

        // Make sure this is not being transcluded (we don't want to show this
        // information to all users just because the user that saves the edit can
        // patrol or is logged in)
        if ( !$this->including() && $this->getUser()->useRCPatrol() ) {
            $this->registerFiltersFromDefinitions( $this->legacyReviewStatusFilterGroupDefinition );
            $this->registerFiltersFromDefinitions( $this->reviewStatusFilterGroupDefinition );
        }

        $changeTypeGroup = $this->getFilterGroup( 'changeType' );

        if ( $this->getConfig()->get( 'RCWatchCategoryMembership' ) ) {
            $transformedHideCategorizationDef = $this->transformFilterDefinition(
                $this->hideCategorizationFilterDefinition
            );

            $transformedHideCategorizationDef['group'] = $changeTypeGroup;

            $hideCategorization = new ChangesListBooleanFilter(
                $transformedHideCategorizationDef
            );
        }

        Hooks::run( 'ChangesListSpecialPageStructuredFilters', [ $this ] );

        $this->registerFiltersFromDefinitions( [] );

        $userExperienceLevel = $this->getFilterGroup( 'userExpLevel' );
        $registered = $userExperienceLevel->getFilter( 'registered' );
        $registered->setAsSupersetOf( $userExperienceLevel->getFilter( 'newcomer' ) );
        $registered->setAsSupersetOf( $userExperienceLevel->getFilter( 'learner' ) );
        $registered->setAsSupersetOf( $userExperienceLevel->getFilter( 'experienced' ) );

        $categoryFilter = $changeTypeGroup->getFilter( 'hidecategorization' );
        $logactionsFilter = $changeTypeGroup->getFilter( 'hidelog' );
        $pagecreationFilter = $changeTypeGroup->getFilter( 'hidenewpages' );

        $significanceTypeGroup = $this->getFilterGroup( 'significance' );
        $hideMinorFilter = $significanceTypeGroup->getFilter( 'hideminor' );

        // categoryFilter is conditional; see registerFilters
        if ( $categoryFilter !== null ) {
            $hideMinorFilter->conflictsWith(
                $categoryFilter,
                'rcfilters-hideminor-conflicts-typeofchange-global',
                'rcfilters-hideminor-conflicts-typeofchange',
                'rcfilters-typeofchange-conflicts-hideminor'
            );
        }
        $hideMinorFilter->conflictsWith(
            $logactionsFilter,
            'rcfilters-hideminor-conflicts-typeofchange-global',
            'rcfilters-hideminor-conflicts-typeofchange',
            'rcfilters-typeofchange-conflicts-hideminor'
        );
        $hideMinorFilter->conflictsWith(
            $pagecreationFilter,
            'rcfilters-hideminor-conflicts-typeofchange-global',
            'rcfilters-hideminor-conflicts-typeofchange',
            'rcfilters-typeofchange-conflicts-hideminor'
        );
    }

    protected function transformFilterDefinition( array $filterDefinition ) {
        return $filterDefinition;
    }

    protected function registerFiltersFromDefinitions( array $definition ) {
        $autoFillPriority = -1;
        foreach ( $definition as $groupDefinition ) {
            if ( !isset( $groupDefinition['priority'] ) ) {
                $groupDefinition['priority'] = $autoFillPriority;
            } else {
                // If it's explicitly specified, start over the auto-fill
                $autoFillPriority = $groupDefinition['priority'];
            }

            $autoFillPriority--;

            $className = $groupDefinition['class'];
            unset( $groupDefinition['class'] );

            foreach ( $groupDefinition['filters'] as &$filterDefinition ) {
                $filterDefinition = $this->transformFilterDefinition( $filterDefinition );
            }

            $this->registerFilterGroup( new $className( $groupDefinition ) );
        }
    }

    protected function getLegacyShowHideFilters() {
        $filters = [];
        foreach ( $this->filterGroups as $group ) {
            if ( $group instanceof ChangesListBooleanFilterGroup ) {
                foreach ( $group->getFilters() as $key => $filter ) {
                    if ( $filter->displaysOnUnstructuredUi() ) {
                        $filters[ $key ] = $filter;
                    }
                }
            }
        }
        return $filters;
    }

    public function setup( $parameters ) {
        $this->registerFilters();

        $opts = $this->getDefaultOptions();

        $opts = $this->fetchOptionsFromRequest( $opts );

        // Give precedence to subpage syntax
        if ( $parameters !== null ) {
            $this->parseParameters( $parameters, $opts );
        }

        $this->validateOptions( $opts );

        return $opts;
    }

    public function getDefaultOptions() {
        $opts = new FormOptions();
        $structuredUI = $this->isStructuredFilterUiEnabled();
        // If urlversion=2 is set, ignore the filter defaults and set them all to false/empty
        $useDefaults = $this->getRequest()->getInt( 'urlversion' ) !== 2;

        foreach ( $this->filterGroups as $filterGroup ) {
            $filterGroup->addOptions( $opts, $useDefaults, $structuredUI );
        }

        $opts->add( 'namespace', '', FormOptions::STRING );
        $opts->add( 'invert', false );
        $opts->add( 'associated', false );
        $opts->add( 'urlversion', 1 );
        $opts->add( 'tagfilter', '' );

        $opts->add( 'days', $this->getDefaultDays(), FormOptions::FLOAT );
        $opts->add( 'limit', $this->getDefaultLimit(), FormOptions::INT );

        $opts->add( 'from', '' );

        return $opts;
    }

    public function registerFilterGroup( ChangesListFilterGroup $group ) {
        $groupName = $group->getName();

        $this->filterGroups[$groupName] = $group;
    }

    protected function getFilterGroups() {
        return $this->filterGroups;
    }

    public function getFilterGroup( $groupName ) {
        return $this->filterGroups[$groupName] ?? null;
    }

    // Currently, this intentionally only includes filters that display
    // in the structured UI.  This can be changed easily, though, if we want
    // to include data on filters that use the unstructured UI.  messageKeys is a
    // special top-level value, with the value being an array of the message keys to
    // send to the client.

    public function getStructuredFilterJsData() {
        $output = [
            'groups' => [],
            'messageKeys' => [],
        ];

        usort( $this->filterGroups, function ( $a, $b ) {
            return $b->getPriority() <=> $a->getPriority();
        } );

        foreach ( $this->filterGroups as $groupName => $group ) {
            $groupOutput = $group->getJsData();
            if ( $groupOutput !== null ) {
                $output['messageKeys'] = array_merge(
                    $output['messageKeys'],
                    $groupOutput['messageKeys']
                );

                unset( $groupOutput['messageKeys'] );
                $output['groups'][] = $groupOutput;
            }
        }

        return $output;
    }

    protected function fetchOptionsFromRequest( $opts ) {
        $opts->fetchValuesFromRequest( $this->getRequest() );

        return $opts;
    }

    public function parseParameters( $par, FormOptions $opts ) {
        $stringParameterNameSet = [];
        $hideParameterNameSet = [];

        // URL parameters can be per-group, like 'userExpLevel',
        // or per-filter, like 'hideminor'.

        foreach ( $this->filterGroups as $filterGroup ) {
            if ( $filterGroup instanceof ChangesListStringOptionsFilterGroup ) {
                $stringParameterNameSet[$filterGroup->getName()] = true;
            } elseif ( $filterGroup instanceof ChangesListBooleanFilterGroup ) {
                foreach ( $filterGroup->getFilters() as $filter ) {
                    $hideParameterNameSet[$filter->getName()] = true;
                }
            }
        }

        $bits = preg_split( '/\s*,\s*/', trim( $par ) );
        foreach ( $bits as $bit ) {
            $m = [];
            if ( isset( $hideParameterNameSet[$bit] ) ) {
                // hidefoo => hidefoo=true
                $opts[$bit] = true;
            } elseif ( isset( $hideParameterNameSet["hide$bit"] ) ) {
                // foo => hidefoo=false
                $opts["hide$bit"] = false;
            } elseif ( preg_match( '/^(.*)=(.*)$/', $bit, $m ) ) {
                if ( isset( $stringParameterNameSet[$m[1]] ) ) {
                    $opts[$m[1]] = $m[2];
                }
            }
        }
    }

    public function validateOptions( FormOptions $opts ) {
        $isContradictory = $this->fixContradictoryOptions( $opts );
        $isReplaced = $this->replaceOldOptions( $opts );

        if ( $isContradictory || $isReplaced ) {
            $query = wfArrayToCgi( $this->convertParamsForLink( $opts->getChangedValues() ) );
            $this->getOutput()->redirect( $this->getPageTitle()->getCanonicalURL( $query ) );
        }

        $opts->validateIntBounds( 'limit', 0, 5000 );
        $opts->validateBounds( 'days', 0, $this->getConfig()->get( 'RCMaxAge' ) / ( 3600 * 24 ) );
    }

    private function fixContradictoryOptions( FormOptions $opts ) {
        $fixed = $this->fixBackwardsCompatibilityOptions( $opts );

        foreach ( $this->filterGroups as $filterGroup ) {
            if ( $filterGroup instanceof ChangesListBooleanFilterGroup ) {
                $filters = $filterGroup->getFilters();

                if ( count( $filters ) === 1 ) {
                    // legacy boolean filters should not be considered
                    continue;
                }

                $allInGroupEnabled = array_reduce(
                    $filters,
                    function ( $carry, $filter ) use ( $opts ) {
                        return $carry && $opts[ $filter->getName() ];
                    },
                    /* initialValue */ count( $filters ) > 0
                );

                if ( $allInGroupEnabled ) {
                    foreach ( $filters as $filter ) {
                        $opts[ $filter->getName() ] = false;
                    }

                    $fixed = true;
                }
            }
        }

        return $fixed;
    }

    private function fixBackwardsCompatibilityOptions( FormOptions $opts ) {
        if ( $opts['hideanons'] && $opts['hideliu'] ) {
            $opts->reset( 'hideanons' );
            if ( !$opts['hidebots'] ) {
                $opts->reset( 'hideliu' );
                $opts['hidehumans'] = 1;
            }

            return true;
        }

        return false;
    }

    public function replaceOldOptions( FormOptions $opts ) {
        if ( !$this->isStructuredFilterUiEnabled() ) {
            return false;
        }

        $changed = false;

        // At this point 'hideanons' and 'hideliu' cannot be both true,
        // because fixBackwardsCompatibilityOptions resets (at least) 'hideanons' in such case
        if ( $opts[ 'hideanons' ] ) {
            $opts->reset( 'hideanons' );
            $opts[ 'userExpLevel' ] = 'registered';
            $changed = true;
        }

        if ( $opts[ 'hideliu' ] ) {
            $opts->reset( 'hideliu' );
            $opts[ 'userExpLevel' ] = 'unregistered';
            $changed = true;
        }

        if ( $this->getFilterGroup( 'legacyReviewStatus' ) ) {
            if ( $opts[ 'hidepatrolled' ] ) {
                $opts->reset( 'hidepatrolled' );
                $opts[ 'reviewStatus' ] = 'unpatrolled';
                $changed = true;
            }

            if ( $opts[ 'hideunpatrolled' ] ) {
                $opts->reset( 'hideunpatrolled' );
                $opts[ 'reviewStatus' ] = implode(
                    ChangesListStringOptionsFilterGroup::SEPARATOR,
                    [ 'manual', 'auto' ]
                );
                $changed = true;
            }
        }

        return $changed;
    }

    protected function convertParamsForLink( $params ) {
        foreach ( $params as &$value ) {
            if ( $value === false ) {
                $value = '0';
            }
        }
        unset( $value );
        return $params;
    }

    protected function buildQuery( &$tables, &$fields, &$conds, &$query_options,
        &$join_conds, FormOptions $opts
    ) {
        $dbr = $this->getDB();
        $isStructuredUI = $this->isStructuredFilterUiEnabled();

        foreach ( $this->filterGroups as $filterGroup ) {
            $filterGroup->modifyQuery( $dbr, $this, $tables, $fields, $conds,
                $query_options, $join_conds, $opts, $isStructuredUI );
        }

        // Namespace filtering
        if ( $opts[ 'namespace' ] !== '' ) {
            $namespaces = explode( ';', $opts[ 'namespace' ] );

            $namespaces = $this->expandSymbolicNamespaceFilters( $namespaces );

            if ( $opts[ 'associated' ] ) {
                $namespaceInfo = MediaWikiServices::getInstance()->getNamespaceInfo();
                $associatedNamespaces = array_map(
                    function ( $ns ) use ( $namespaceInfo ){
                        return $namespaceInfo->getAssociated( $ns );
                    },
                    array_filter(
                        $namespaces,
                        function ( $ns ) use ( $namespaceInfo ) {
                            return $namespaceInfo->hasTalkNamespace( $ns );
                        }
                    )
                );
                $namespaces = array_unique( array_merge( $namespaces, $associatedNamespaces ) );
            }

            if ( count( $namespaces ) === 1 ) {
                $operator = $opts[ 'invert' ] ? '!=' : '=';
                $value = $dbr->addQuotes( reset( $namespaces ) );
            } else {
                $operator = $opts[ 'invert' ] ? 'NOT IN' : 'IN';
                sort( $namespaces );
                $value = '(' . $dbr->makeList( $namespaces ) . ')';
            }
            $conds[] = "rc_namespace $operator $value";
        }

        // Calculate cutoff
        $cutoff_unixtime = time() - $opts['days'] * 3600 * 24;
        $cutoff = $dbr->timestamp( $cutoff_unixtime );

        $fromValid = preg_match( '/^[0-9]{14}$/', $opts['from'] );
        if ( $fromValid && $opts['from'] > wfTimestamp( TS_MW, $cutoff ) ) {
            $cutoff = $dbr->timestamp( $opts['from'] );
        } else {
            $opts->reset( 'from' );
        }

        $conds[] = 'rc_timestamp >= ' . $dbr->addQuotes( $cutoff );
    }

    protected function doMainQuery( $tables, $fields, $conds,
        $query_options, $join_conds, FormOptions $opts
    ) {
        $rcQuery = RecentChange::getQueryInfo();
        $tables = array_merge( $tables, $rcQuery['tables'] );
        $fields = array_merge( $rcQuery['fields'], $fields );
        $join_conds = array_merge( $join_conds, $rcQuery['joins'] );

        ChangeTags::modifyDisplayQuery(
            $tables,
            $fields,
            $conds,
            $join_conds,
            $query_options,
            ''
        );

        if ( !$this->runMainQueryHook( $tables, $fields, $conds, $query_options, $join_conds,
            $opts )
        ) {
            return false;
        }

        $dbr = $this->getDB();

        return $dbr->select(
            $tables,
            $fields,
            $conds,
            __METHOD__,
            $query_options,
            $join_conds
        );
    }

    protected function runMainQueryHook( &$tables, &$fields, &$conds,
        &$query_options, &$join_conds, $opts
    ) {
        return Hooks::run(
            'ChangesListSpecialPageQuery',
            [ $this->getName(), &$tables, &$fields, &$conds, &$query_options, &$join_conds, $opts ]
        );
    }

    protected function getDB() {
        return wfGetDB( DB_REPLICA );
    }

    private function webOutputHeader( $rowCount, $opts ) {
        if ( !$this->including() ) {
            $this->outputFeedLinks();
            $this->doHeader( $opts, $rowCount );
        }
    }

    public function webOutput( $rows, $opts ) {
        $this->webOutputHeader( $rows->numRows(), $opts );

        $this->outputChangesList( $rows, $opts );
    }

    public function outputFeedLinks() {
        // nothing by default
    }

    abstract public function outputChangesList( $rows, $opts );

    public function doHeader( $opts, $numRows ) {
        $this->setTopText( $opts );

        // @todo Lots of stuff should be done here.

        $this->setBottomText( $opts );
    }

    public function setTopText( FormOptions $opts ) {
        // nothing by default
    }

    public function setBottomText( FormOptions $opts ) {
        // nothing by default
    }

    public function getExtraOptions( $opts ) {
        return [];
    }

    public function makeLegend() {
        $context = $this->getContext();
        $user = $context->getUser();
        # The legend showing what the letters and stuff mean
        $legend = Html::openElement( 'dl' ) . "\n";
        # Iterates through them and gets the messages for both letter and tooltip
        $legendItems = $context->getConfig()->get( 'RecentChangesFlags' );
        if ( !( $user->useRCPatrol() || $user->useNPPatrol() ) ) {
            unset( $legendItems['unpatrolled'] );
        }
        foreach ( $legendItems as $key => $item ) { # generate items of the legend
            $label = $item['legend'] ?? $item['title'];
            $letter = $item['letter'];
            $cssClass = $item['class'] ?? $key;

            $legend .= Html::element( 'dt',
                [ 'class' => $cssClass ], $context->msg( $letter )->text()
            ) . "\n" .
            Html::rawElement( 'dd',
                [ 'class' => Sanitizer::escapeClass( 'mw-changeslist-legend-' . $key ) ],
                $context->msg( $label )->parse()
            ) . "\n";
        }
        # (+-123)
        $legend .= Html::rawElement( 'dt',
            [ 'class' => 'mw-plusminus-pos' ],
            $context->msg( 'recentchanges-legend-plusminus' )->parse()
        ) . "\n";
        $legend .= Html::element(
            'dd',
            [ 'class' => 'mw-changeslist-legend-plusminus' ],
            $context->msg( 'recentchanges-label-plusminus' )->text()
        ) . "\n";
        $legend .= Html::closeElement( 'dl' ) . "\n";

        $legendHeading = $this->isStructuredFilterUiEnabled() ?
            $context->msg( 'rcfilters-legend-heading' )->parse() :
            $context->msg( 'recentchanges-legend-heading' )->parse();

        # Collapsible
        $collapsedState = $this->getRequest()->getCookie( 'changeslist-state' );
        $collapsedClass = $collapsedState === 'collapsed' ? ' mw-collapsed' : '';

        $legend =
            '<div class="mw-changeslist-legend mw-collapsible' . $collapsedClass . '">' .
                $legendHeading .
                '<div class="mw-collapsible-content">' . $legend . '</div>' .
            '</div>';

        return $legend;
    }

    protected function addModules() {
        $out = $this->getOutput();
        // Styles and behavior for the legend box (see makeLegend())
        $out->addModuleStyles( [
            'mediawiki.interface.helpers.styles',
            'mediawiki.special.changeslist.legend',
            'mediawiki.special.changeslist',
        ] );
        $out->addModules( 'mediawiki.special.changeslist.legend.js' );

        if ( $this->isStructuredFilterUiEnabled() && !$this->including() ) {
            $out->addModules( 'mediawiki.rcfilters.filters.ui' );
            $out->addModuleStyles( 'mediawiki.rcfilters.filters.base.styles' );
        }
    }

    protected function getGroupName() {
        return 'changes';
    }

    public function filterOnUserExperienceLevel( $specialPageClassName, $context, $dbr,
        &$tables, &$fields, &$conds, &$query_options, &$join_conds, $selectedExpLevels, $now = 0
    ) {
        global $wgLearnerEdits,
            $wgExperiencedUserEdits,
            $wgLearnerMemberSince,
            $wgExperiencedUserMemberSince;

        $LEVEL_COUNT = 5;

        // If all levels are selected, don't filter
        if ( count( $selectedExpLevels ) === $LEVEL_COUNT ) {
            return;
        }

        // both 'registered' and 'unregistered', experience levels, if any, are included in 'registered'
        if (
            in_array( 'registered', $selectedExpLevels ) &&
            in_array( 'unregistered', $selectedExpLevels )
        ) {
            return;
        }

        $actorMigration = ActorMigration::newMigration();
        $actorQuery = $actorMigration->getJoin( 'rc_user' );
        $tables += $actorQuery['tables'];
        $join_conds += $actorQuery['joins'];

        // 'registered' but not 'unregistered', experience levels, if any, are included in 'registered'
        if (
            in_array( 'registered', $selectedExpLevels ) &&
            !in_array( 'unregistered', $selectedExpLevels )
        ) {
            $conds[] = $actorMigration->isNotAnon( $actorQuery['fields']['rc_user'] );
            return;
        }

        if ( $selectedExpLevels === [ 'unregistered' ] ) {
            $conds[] = $actorMigration->isAnon( $actorQuery['fields']['rc_user'] );
            return;
        }

        $tables[] = 'user';
        $join_conds['user'] = [ 'LEFT JOIN', $actorQuery['fields']['rc_user'] . ' = user_id' ];

        if ( $now === 0 ) {
            $now = time();
        }
        $secondsPerDay = 86400;
        $learnerCutoff = $now - $wgLearnerMemberSince * $secondsPerDay;
        $experiencedUserCutoff = $now - $wgExperiencedUserMemberSince * $secondsPerDay;

        $aboveNewcomer = $dbr->makeList(
            [
                'user_editcount >= ' . intval( $wgLearnerEdits ),
                'user_registration <= ' . $dbr->addQuotes( $dbr->timestamp( $learnerCutoff ) ),
            ],
            IDatabase::LIST_AND
        );

        $aboveLearner = $dbr->makeList(
            [
                'user_editcount >= ' . intval( $wgExperiencedUserEdits ),
                'user_registration <= ' .
                    $dbr->addQuotes( $dbr->timestamp( $experiencedUserCutoff ) ),
            ],
            IDatabase::LIST_AND
        );

        $conditions = [];

        if ( in_array( 'unregistered', $selectedExpLevels ) ) {
            $selectedExpLevels = array_diff( $selectedExpLevels, [ 'unregistered' ] );
            $conditions[] = $actorMigration->isAnon( $actorQuery['fields']['rc_user'] );
        }

        if ( $selectedExpLevels === [ 'newcomer' ] ) {
            $conditions[] = "NOT ( $aboveNewcomer )";
        } elseif ( $selectedExpLevels === [ 'learner' ] ) {
            $conditions[] = $dbr->makeList(
                [ $aboveNewcomer, "NOT ( $aboveLearner )" ],
                IDatabase::LIST_AND
            );
        } elseif ( $selectedExpLevels === [ 'experienced' ] ) {
            $conditions[] = $aboveLearner;
        } elseif ( $selectedExpLevels === [ 'learner', 'newcomer' ] ) {
            $conditions[] = "NOT ( $aboveLearner )";
        } elseif ( $selectedExpLevels === [ 'experienced', 'newcomer' ] ) {
            $conditions[] = $dbr->makeList(
                [ "NOT ( $aboveNewcomer )", $aboveLearner ],
                IDatabase::LIST_OR
            );
        } elseif ( $selectedExpLevels === [ 'experienced', 'learner' ] ) {
            $conditions[] = $aboveNewcomer;
        } elseif ( $selectedExpLevels === [ 'experienced', 'learner', 'newcomer' ] ) {
            $conditions[] = $actorMigration->isNotAnon( $actorQuery['fields']['rc_user'] );
        }

        if ( count( $conditions ) > 1 ) {
            $conds[] = $dbr->makeList( $conditions, IDatabase::LIST_OR );
        } elseif ( count( $conditions ) === 1 ) {
            $conds[] = reset( $conditions );
        }
    }

    public function isStructuredFilterUiEnabled() {
        if ( $this->getRequest()->getBool( 'rcfilters' ) ) {
            return true;
        }

        return static::checkStructuredFilterUiEnabled( $this->getUser() );
    }

    public static function checkStructuredFilterUiEnabled( $user ) {
        if ( $user instanceof Config ) {
            wfDeprecated( __METHOD__ . ' with Config argument', '1.34' );
            $user = func_get_arg( 1 );
        }
        return !$user->getOption( 'rcenhancedfilters-disable' );
    }

    public function getDefaultLimit() {
        return $this->getUser()->getIntOption( static::$limitPreferenceName );
    }

    public function getDefaultDays() {
        return floatval( $this->getUser()->getOption( static::$daysPreferenceName ) );
    }

    private function expandSymbolicNamespaceFilters( array $namespaces ) {
        $nsInfo = MediaWikiServices::getInstance()->getNamespaceInfo();
        $symbolicFilters = [
            'all-contents' => $nsInfo->getSubjectNamespaces(),
            'all-discussions' => $nsInfo->getTalkNamespaces(),
        ];
        $additionalNamespaces = [];
        foreach ( $symbolicFilters as $name => $values ) {
            if ( in_array( $name, $namespaces ) ) {
                $additionalNamespaces = array_merge( $additionalNamespaces, $values );
            }
        }
        $namespaces = array_diff( $namespaces, array_keys( $symbolicFilters ) );
        $namespaces = array_merge( $namespaces, $additionalNamespaces );
        return array_unique( $namespaces );
    }
}