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[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.
 *
 * @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 = array(), $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 = array(), $offset = 0 ) {
                $search = trim( $search );
                if ( $search == '' ) {
                        return array(); // Return empty result
                }
                $namespaces = $this->validateNamespaces( $namespaces );

                // Find a Title which is not an interwiki and is in NS_MAIN
                $title = Title::newFromText( $search );
                if ( $title && !$title->isExternal() ) {
                        $ns = array( $title->getNamespace() );
                        $search = $title->getText();
                        if ( $ns[0] == NS_MAIN ) {
                                $ns = $namespaces; // no explicit prefix, use default namespaces
                                Hooks::run( 'PrefixSearchExtractNamespace', array( &$ns, &$search ) );
                        }
                        return $this->searchBackend( $ns, $search, $limit, $offset );
                }

                // Is this a namespace prefix?
                $title = Title::newFromText( $search . 'Dummy' );
                if ( $title && $title->getText() == 'Dummy'
                        && $title->getNamespace() != NS_MAIN
                        && !$title->isExternal() )
                {
                        $namespaces = array( $title->getNamespace() );
                        $search = '';
                } else {
                        Hooks::run( 'PrefixSearchExtractNamespace', array( &$namespaces, &$search ) );
                }

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

        /**
         * 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 ), array( $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 = array( NS_FILE );
                        } elseif ( $ns == NS_SPECIAL ) {
                                return $this->titles( $this->specialSearch( $search, $limit, $offset ) );
                        }
                }
                $srchres = array();
                if ( Hooks::run(
                        'PrefixSearchBackend',
                        array( $namespaces, $search, $limit, &$srchres, $offset )
                ) ) {
                        return $this->titles( $this->defaultSearchBackend( $namespaces, $search, $limit, $offset ) );
                }
                return $this->strings( $this->handleResultFromHook( $srchres, $namespaces, $search, $limit ) );
        }

        /**
         * Default search backend does proper prefix searching, but custom backends
         * may sort based on other algorythms that may cause the exact title match
         * to not be in the results or be lower down the list.
         * @param array $srchres results from the hook
         * @return array munged results from the hook
         */
        private function handleResultFromHook( $srchres, $namespaces, $search, $limit ) {
                // Pick namespace (based on PrefixSearch::defaultSearchBackend)
                $ns = in_array( NS_MAIN, $namespaces ) ? NS_MAIN : $namespaces[0];
                $t = Title::newFromText( $search, $ns );
                if ( !$t || !$t->exists() ) {
                        // No exact match so just return the search results
                        return $srchres;
                }
                $string = $t->getPrefixedText();
                $key = array_search( $string, $srchres );
                if ( $key !== false ) {
                        // Exact match was in the results so just move it to the front
                        return $this->pullFront( $key, $srchres );
                }
                // Exact match not in the search results so check for some redirect handling cases
                if ( $t->isRedirect() ) {
                        $target = $this->getRedirectTarget( $t );
                        $key = array_search( $target, $srchres );
                        if ( $key !== false ) {
                                // Exact match is a redirect to one of the returned matches so pull the
                                // returned match to the front.  This might look odd but the alternative
                                // is to put the redirect in front and drop the match.  The name of the
                                // found match is often more descriptive/better formed than the name of
                                // the redirect AND by definition they share a prefix.  Hopefully this
                                // choice is less confusing and more helpful.  But it might not be.  But
                                // it is the choice we're going with for now.
                                return $this->pullFront( $key, $srchres );
                        }
                        $redirectTargetsToRedirect = $this->redirectTargetsToRedirect( $srchres );
                        if ( isset( $redirectTargetsToRedirect[$target] ) ) {
                                // The exact match and something in the results list are both redirects
                                // to the same thing!  In this case we'll pull the returned match to the
                                // top following the same logic above.  Again, it might not be a perfect
                                // choice but it'll do.
                                return $this->pullFront( $redirectTargetsToRedirect[$target], $srchres );
                        }
                } else {
                        $redirectTargetsToRedirect = $this->redirectTargetsToRedirect( $srchres );
                        if ( isset( $redirectTargetsToRedirect[$string] ) ) {
                                // The exact match is the target of a redirect already in the results list so remove
                                // the redirect from the results list and push the exact match to the front
                                array_splice( $srchres, $redirectTargetsToRedirect[$string], 1 );
                                array_unshift( $srchres, $string );
                                return $srchres;
                        }
                }

                // Exact match is totally unique from the other results so just add it to the front
                array_unshift( $srchres, $string );
                // And roll one off the end if the results are too long
                if ( count( $srchres ) > $limit ) {
                        array_pop( $srchres );
                }
                return $srchres;
        }

        /**
         * @param Array(string) $titles as strings
         * @return Array(string => int) redirect target prefixedText to index of title in titles
         *   that is a redirect to it.
         */
        private function redirectTargetsToRedirect( $titles ) {
                $result = array();
                foreach ( $titles as $key => $titleText ) {
                        $title = Title::newFromText( $titleText );
                        if ( !$title || !$title->isRedirect() ) {
                                continue;
                        }
                        $target = $this->getRedirectTarget( $title );
                        if ( !$target ) {
                                continue;
                        }
                        $result[$target] = $key;
                }
                return $result;
        }

        /**
         * @param int $key key to pull to the front
         * @return array $array with the item at $key pulled to the front
         */
        private function pullFront( $key, $array ) {
                $cut = array_splice( $array, $key, 1 );
                array_unshift( $array, $cut[0] );
                return $array;
        }

        private function getRedirectTarget( $title ) {
                $page = WikiPage::factory( $title );
                if ( !$page->exists() ) {
                        return null;
                }
                return $page->getRedirectTarget()->getPrefixedText();
        }

        /**
         * 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 array();
                        }
                        $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 array();
                        }
                }

                # 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 = array();
                foreach ( SpecialPageFactory::getNames() as $page ) {
                        $keys[$wgContLang->caseFold( $page )] = $page;
                }

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

                        foreach ( $aliases as $alias ) {
                                $keys[$wgContLang->caseFold( $alias )] = $alias;
                        }
                }
                ksort( $keys );

                $srchres = array();
                $skipped = 0;
                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'
                                if ( $offset > 0 && $skipped < $offset ) {
                                        $skipped++;
                                        continue;
                                }
                                $srchres[] = Title::makeTitleSafe( NS_SPECIAL, $page );
                        }

                        if ( count( $srchres ) >= $limit ) {
                                break;
                        }
                }

                return $srchres;
        }

        /**
         * 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 $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 array Array of Title objects
         */
        protected function defaultSearchBackend( $namespaces, $search, $limit, $offset ) {
                $ns = array_shift( $namespaces ); // support only one namespace
                if ( in_array( NS_MAIN, $namespaces ) ) {
                        $ns = NS_MAIN; // if searching on many always default to main
                }

                $t = Title::newFromText( $search, $ns );
                $prefix = $t ? $t->getDBkey() : '';
                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select( 'page',
                        array( 'page_id', 'page_namespace', 'page_title' ),
                        array(
                                'page_namespace' => $ns,
                                'page_title ' . $dbr->buildLike( $prefix, $dbr->anyString() )
                        ),
                        __METHOD__,
                        array(
                                'LIMIT' => $limit,
                                'ORDER BY' => 'page_title',
                                'OFFSET' => $offset
                        )
                );
                $srchres = array();
                foreach ( $res as $row ) {
                        $srchres[] = Title::newFromRow( $row );
                }
                return $srchres;
        }

        /**
         * 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 = array();
                        foreach ( $namespaces as $ns ) {
                                if ( is_numeric( $ns ) && array_key_exists( $ns, $validNamespaces ) ) {
                                        $valid[] = $ns;
                                }
                        }
                        if ( count( $valid ) > 0 ) {
                                return $valid;
                        }
                }

                return array( NS_MAIN );
        }
}

/**
 * Performs prefix search, returning Title objects
 * @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
 * @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;
        }
}