Move ILoadBalancer to Rdbms namespace

[mediawiki.git] / includes / PrefixSearch.php

<?php
/**
 * Prefix search of page names.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

/**
 * Handles searching prefixes of titles and finding any page
 * names that match. Used largely by the OpenSearch implementation.
 * @deprecated Since 1.27, Use SearchEngine::defaultPrefixSearch or SearchEngine::completionSearch
 *
 * @ingroup Search
 */
abstract class PrefixSearch {
        /**
         * Do a prefix search of titles and return a list of matching page names.
         * @deprecated Since 1.23, use TitlePrefixSearch or StringPrefixSearch classes
         *
         * @param string $search
         * @param int $limit
         * @param array $namespaces Used if query is not explicitly prefixed
         * @param int $offset How many results to offset from the beginning
         * @return array Array of strings
         */
        public static function titleSearch( $search, $limit, $namespaces = [], $offset = 0 ) {
                $prefixSearch = new StringPrefixSearch;
                return $prefixSearch->search( $search, $limit, $namespaces, $offset );
        }

        /**
         * Do a prefix search of titles and return a list of matching page names.
         *
         * @param string $search
         * @param int $limit
         * @param array $namespaces Used if query is not explicitly prefixed
         * @param int $offset How many results to offset from the beginning
         * @return array Array of strings or Title objects
         */
        public function search( $search, $limit, $namespaces = [], $offset = 0 ) {
                $search = trim( $search );
                if ( $search == '' ) {
                        return []; // Return empty result
                }

                $hasNamespace = $this->extractNamespace( $search );
                if ( $hasNamespace ) {
                        list( $namespace, $search ) = $hasNamespace;
                        $namespaces = [ $namespace ];
                } else {
                        $namespaces = $this->validateNamespaces( $namespaces );
                        Hooks::run( 'PrefixSearchExtractNamespace', [ &$namespaces, &$search ] );
                }

                return $this->searchBackend( $namespaces, $search, $limit, $offset );
        }

        /**
         * Figure out if given input contains an explicit namespace.
         *
         * @param string $input
         * @return false|array Array of namespace and remaining text, or false if no namespace given.
         */
        protected function extractNamespace( $input ) {
                if ( strpos( $input, ':' ) === false ) {
                        return false;
                }

                // Namespace prefix only
                $title = Title::newFromText( $input . 'Dummy' );
                if (
                        $title &&
                        $title->getText() === 'Dummy' &&
                        !$title->inNamespace( NS_MAIN ) &&
                        !$title->isExternal()
                ) {
                        return [ $title->getNamespace(), '' ];
                }

                // Namespace prefix with additional input
                $title = Title::newFromText( $input );
                if (
                        $title &&
                        !$title->inNamespace( NS_MAIN ) &&
                        !$title->isExternal()
                ) {
                        // getText provides correct capitalization
                        return [ $title->getNamespace(), $title->getText() ];
                }

                return false;
        }

        /**
         * Do a prefix search for all possible variants of the prefix
         * @param string $search
         * @param int $limit
         * @param array $namespaces
         * @param int $offset How many results to offset from the beginning
         *
         * @return array
         */
        public function searchWithVariants( $search, $limit, array $namespaces, $offset = 0 ) {
                $searches = $this->search( $search, $limit, $namespaces, $offset );

                // if the content language has variants, try to retrieve fallback results
                $fallbackLimit = $limit - count( $searches );
                if ( $fallbackLimit > 0 ) {
                        global $wgContLang;

                        $fallbackSearches = $wgContLang->autoConvertToAllVariants( $search );
                        $fallbackSearches = array_diff( array_unique( $fallbackSearches ), [ $search ] );

                        foreach ( $fallbackSearches as $fbs ) {
                                $fallbackSearchResult = $this->search( $fbs, $fallbackLimit, $namespaces );
                                $searches = array_merge( $searches, $fallbackSearchResult );
                                $fallbackLimit -= count( $fallbackSearchResult );

                                if ( $fallbackLimit == 0 ) {
                                        break;
                                }
                        }
                }
                return $searches;
        }

        /**
         * When implemented in a descendant class, receives an array of Title objects and returns
         * either an unmodified array or an array of strings corresponding to titles passed to it.
         *
         * @param array $titles
         * @return array
         */
        abstract protected function titles( array $titles );

        /**
         * When implemented in a descendant class, receives an array of titles as strings and returns
         * either an unmodified array or an array of Title objects corresponding to strings received.
         *
         * @param array $strings
         *
         * @return array
         */
        abstract protected function strings( array $strings );

        /**
         * Do a prefix search of titles and return a list of matching page names.
         * @param array $namespaces
         * @param string $search
         * @param int $limit
         * @param int $offset How many results to offset from the beginning
         * @return array Array of strings
         */
        protected function searchBackend( $namespaces, $search, $limit, $offset ) {
                if ( count( $namespaces ) == 1 ) {
                        $ns = $namespaces[0];
                        if ( $ns == NS_MEDIA ) {
                                $namespaces = [ NS_FILE ];
                        } elseif ( $ns == NS_SPECIAL ) {
                                return $this->titles( $this->specialSearch( $search, $limit, $offset ) );
                        }
                }
                $srchres = [];
                if ( Hooks::run(
                        'PrefixSearchBackend',
                        [ $namespaces, $search, $limit, &$srchres, $offset ]
                ) ) {
                        return $this->titles( $this->defaultSearchBackend( $namespaces, $search, $limit, $offset ) );
                }
                return $this->strings(
                        $this->handleResultFromHook( $srchres, $namespaces, $search, $limit, $offset ) );
        }

        private function handleResultFromHook( $srchres, $namespaces, $search, $limit, $offset ) {
                if ( $offset === 0 ) {
                        // Only perform exact db match if offset === 0
                        // This is still far from perfect but at least we avoid returning the
                        // same title afain and again when the user is scrolling with a query
                        // that matches a title in the db.
                        $rescorer = new SearchExactMatchRescorer();
                        $srchres = $rescorer->rescore( $search, $namespaces, $srchres, $limit );
                }
                return $srchres;
        }

        /**
         * Prefix search special-case for Special: namespace.
         *
         * @param string $search Term
         * @param int $limit Max number of items to return
         * @param int $offset Number of items to offset
         * @return array
         */
        protected function specialSearch( $search, $limit, $offset ) {
                global $wgContLang;

                $searchParts = explode( '/', $search, 2 );
                $searchKey = $searchParts[0];
                $subpageSearch = isset( $searchParts[1] ) ? $searchParts[1] : null;

                // Handle subpage search separately.
                if ( $subpageSearch !== null ) {
                        // Try matching the full search string as a page name
                        $specialTitle = Title::makeTitleSafe( NS_SPECIAL, $searchKey );
                        if ( !$specialTitle ) {
                                return [];
                        }
                        $special = SpecialPageFactory::getPage( $specialTitle->getText() );
                        if ( $special ) {
                                $subpages = $special->prefixSearchSubpages( $subpageSearch, $limit, $offset );
                                return array_map( function ( $sub ) use ( $specialTitle ) {
                                        return $specialTitle->getSubpage( $sub );
                                }, $subpages );
                        } else {
                                return [];
                        }
                }

                # normalize searchKey, so aliases with spaces can be found - bug 25675
                $searchKey = str_replace( ' ', '_', $searchKey );
                $searchKey = $wgContLang->caseFold( $searchKey );

                // Unlike SpecialPage itself, we want the canonical forms of both
                // canonical and alias title forms...
                $keys = [];
                foreach ( SpecialPageFactory::getNames() as $page ) {
                        $keys[$wgContLang->caseFold( $page )] = [ 'page' => $page, 'rank' => 0 ];
                }

                foreach ( $wgContLang->getSpecialPageAliases() as $page => $aliases ) {
                        if ( !in_array( $page, SpecialPageFactory::getNames() ) ) {# bug 20885
                                continue;
                        }

                        foreach ( $aliases as $key => $alias ) {
                                $keys[$wgContLang->caseFold( $alias )] = [ 'page' => $alias, 'rank' => $key ];
                        }
                }
                ksort( $keys );

                $matches = [];
                foreach ( $keys as $pageKey => $page ) {
                        if ( $searchKey === '' || strpos( $pageKey, $searchKey ) === 0 ) {
                                // bug 27671: Don't use SpecialPage::getTitleFor() here because it
                                // localizes its input leading to searches for e.g. Special:All
                                // returning Spezial:MediaWiki-Systemnachrichten and returning
                                // Spezial:Alle_Seiten twice when $wgLanguageCode == 'de'
                                $matches[$page['rank']][] = Title::makeTitleSafe( NS_SPECIAL, $page['page'] );

                                if ( isset( $matches[0] ) && count( $matches[0] ) >= $limit + $offset ) {
                                        // We have enough items in primary rank, no use to continue
                                        break;
                                }
                        }

                }

                // Ensure keys are in order
                ksort( $matches );
                // Flatten the array
                $matches = array_reduce( $matches, 'array_merge', [] );

                return array_slice( $matches, $offset, $limit );
        }

        /**
         * Unless overridden by PrefixSearchBackend hook...
         * This is case-sensitive (First character may
         * be automatically capitalized by Title::secureAndSpit()
         * later on depending on $wgCapitalLinks)
         *
         * @param array|null $namespaces Namespaces to search in
         * @param string $search Term
         * @param int $limit Max number of items to return
         * @param int $offset Number of items to skip
         * @return Title[] Array of Title objects
         */
        public function defaultSearchBackend( $namespaces, $search, $limit, $offset ) {
                // Backwards compatability with old code. Default to NS_MAIN if no namespaces provided.
                if ( $namespaces === null ) {
                        $namespaces = [];
                }
                if ( !$namespaces ) {
                        $namespaces[] = NS_MAIN;
                }

                // Construct suitable prefix for each namespace. They differ in cases where
                // some namespaces always capitalize and some don't.
                $prefixes = [];
                foreach ( $namespaces as $namespace ) {
                        // For now, if special is included, ignore the other namespaces
                        if ( $namespace == NS_SPECIAL ) {
                                return $this->specialSearch( $search, $limit, $offset );
                        }

                        $title = Title::makeTitleSafe( $namespace, $search );
                        // Why does the prefix default to empty?
                        $prefix = $title ? $title->getDBkey() : '';
                        $prefixes[$prefix][] = $namespace;
                }

                $dbr = wfGetDB( DB_REPLICA );
                // Often there is only one prefix that applies to all requested namespaces,
                // but sometimes there are two if some namespaces do not always capitalize.
                $conds = [];
                foreach ( $prefixes as $prefix => $namespaces ) {
                        $condition = [
                                'page_namespace' => $namespaces,
                                'page_title' . $dbr->buildLike( $prefix, $dbr->anyString() ),
                        ];
                        $conds[] = $dbr->makeList( $condition, LIST_AND );
                }

                $table = 'page';
                $fields = [ 'page_id', 'page_namespace', 'page_title' ];
                $conds = $dbr->makeList( $conds, LIST_OR );
                $options = [
                        'LIMIT' => $limit,
                        'ORDER BY' => [ 'page_title', 'page_namespace' ],
                        'OFFSET' => $offset
                ];

                $res = $dbr->select( $table, $fields, $conds, __METHOD__, $options );

                return iterator_to_array( TitleArray::newFromResult( $res ) );
        }

        /**
         * Validate an array of numerical namespace indexes
         *
         * @param array $namespaces
         * @return array (default: contains only NS_MAIN)
         */
        protected function validateNamespaces( $namespaces ) {
                global $wgContLang;

                // We will look at each given namespace against wgContLang namespaces
                $validNamespaces = $wgContLang->getNamespaces();
                if ( is_array( $namespaces ) && count( $namespaces ) > 0 ) {
                        $valid = [];
                        foreach ( $namespaces as $ns ) {
                                if ( is_numeric( $ns ) && array_key_exists( $ns, $validNamespaces ) ) {
                                        $valid[] = $ns;
                                }
                        }
                        if ( count( $valid ) > 0 ) {
                                return $valid;
                        }
                }

                return [ NS_MAIN ];
        }
}

/**
 * Performs prefix search, returning Title objects
 * @deprecated Since 1.27, Use SearchEngine::defaultPrefixSearch or SearchEngine::completionSearch
 * @ingroup Search
 */
class TitlePrefixSearch extends PrefixSearch {

        protected function titles( array $titles ) {
                return $titles;
        }

        protected function strings( array $strings ) {
                $titles = array_map( 'Title::newFromText', $strings );
                $lb = new LinkBatch( $titles );
                $lb->setCaller( __METHOD__ );
                $lb->execute();
                return $titles;
        }
}

/**
 * Performs prefix search, returning strings
 * @deprecated Since 1.27, Use SearchEngine::prefixSearchSubpages or SearchEngine::completionSearch
 * @ingroup Search
 */
class StringPrefixSearch extends PrefixSearch {

        protected function titles( array $titles ) {
                return array_map( function ( Title $t ) {
                        return $t->getPrefixedText();
                }, $titles );
        }

        protected function strings( array $strings ) {
                return $strings;
        }
}