Move remaining LoadBalancer classes to Rdbms

[mediawiki.git] / includes / api / ApiQueryBase.php

<?php
/**
 *
 *
 * Created on Sep 7, 2006
 *
 * Copyright © 2006 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
 *
 * 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
 */

/**
 * This is a base class for all Query modules.
 * It provides some common functionality such as constructing various SQL
 * queries.
 *
 * @ingroup API
 */
abstract class ApiQueryBase extends ApiBase {

        private $mQueryModule, $mDb, $tables, $where, $fields, $options, $join_conds;

        /**
         * @param ApiQuery $queryModule
         * @param string $moduleName
         * @param string $paramPrefix
         */
        public function __construct( ApiQuery $queryModule, $moduleName, $paramPrefix = '' ) {
                parent::__construct( $queryModule->getMain(), $moduleName, $paramPrefix );
                $this->mQueryModule = $queryModule;
                $this->mDb = null;
                $this->resetQueryParams();
        }

        /************************************************************************//**
         * @name   Methods to implement
         * @{
         */

        /**
         * Get the cache mode for the data generated by this module. Override
         * this in the module subclass. For possible return values and other
         * details about cache modes, see ApiMain::setCacheMode()
         *
         * Public caching will only be allowed if *all* the modules that supply
         * data for a given request return a cache mode of public.
         *
         * @param array $params
         * @return string
         */
        public function getCacheMode( $params ) {
                return 'private';
        }

        /**
         * Override this method to request extra fields from the pageSet
         * using $pageSet->requestField('fieldName')
         *
         * Note this only makes sense for 'prop' modules, as 'list' and 'meta'
         * modules should not be using the pageset.
         *
         * @param ApiPageSet $pageSet
         */
        public function requestExtraData( $pageSet ) {
        }

        /**@}*/

        /************************************************************************//**
         * @name   Data access
         * @{
         */

        /**
         * Get the main Query module
         * @return ApiQuery
         */
        public function getQuery() {
                return $this->mQueryModule;
        }

        /**
         * @see ApiBase::getParent()
         */
        public function getParent() {
                return $this->getQuery();
        }

        /**
         * Get the Query database connection (read-only)
         * @return Database
         */
        protected function getDB() {
                if ( is_null( $this->mDb ) ) {
                        $this->mDb = $this->getQuery()->getDB();
                }

                return $this->mDb;
        }

        /**
         * Selects the query database connection with the given name.
         * See ApiQuery::getNamedDB() for more information
         * @param string $name Name to assign to the database connection
         * @param int $db One of the DB_* constants
         * @param array $groups Query groups
         * @return Database
         */
        public function selectNamedDB( $name, $db, $groups ) {
                $this->mDb = $this->getQuery()->getNamedDB( $name, $db, $groups );
                return $this->mDb;
        }

        /**
         * Get the PageSet object to work on
         * @return ApiPageSet
         */
        protected function getPageSet() {
                return $this->getQuery()->getPageSet();
        }

        /**@}*/

        /************************************************************************//**
         * @name   Querying
         * @{
         */

        /**
         * Blank the internal arrays with query parameters
         */
        protected function resetQueryParams() {
                $this->tables = [];
                $this->where = [];
                $this->fields = [];
                $this->options = [];
                $this->join_conds = [];
        }

        /**
         * Add a set of tables to the internal array
         * @param string|string[] $tables Table name or array of table names
         * @param string|null $alias Table alias, or null for no alias. Cannot be
         *  used with multiple tables
         */
        protected function addTables( $tables, $alias = null ) {
                if ( is_array( $tables ) ) {
                        if ( !is_null( $alias ) ) {
                                ApiBase::dieDebug( __METHOD__, 'Multiple table aliases not supported' );
                        }
                        $this->tables = array_merge( $this->tables, $tables );
                } else {
                        if ( !is_null( $alias ) ) {
                                $this->tables[$alias] = $tables;
                        } else {
                                $this->tables[] = $tables;
                        }
                }
        }

        /**
         * Add a set of JOIN conditions to the internal array
         *
         * JOIN conditions are formatted as [ tablename => [ jointype, conditions ] ]
         * e.g. [ 'page' => [ 'LEFT JOIN', 'page_id=rev_page' ] ].
         * Conditions may be a string or an addWhere()-style array.
         * @param array $join_conds JOIN conditions
         */
        protected function addJoinConds( $join_conds ) {
                if ( !is_array( $join_conds ) ) {
                        ApiBase::dieDebug( __METHOD__, 'Join conditions have to be arrays' );
                }
                $this->join_conds = array_merge( $this->join_conds, $join_conds );
        }

        /**
         * Add a set of fields to select to the internal array
         * @param array|string $value Field name or array of field names
         */
        protected function addFields( $value ) {
                if ( is_array( $value ) ) {
                        $this->fields = array_merge( $this->fields, $value );
                } else {
                        $this->fields[] = $value;
                }
        }

        /**
         * Same as addFields(), but add the fields only if a condition is met
         * @param array|string $value See addFields()
         * @param bool $condition If false, do nothing
         * @return bool $condition
         */
        protected function addFieldsIf( $value, $condition ) {
                if ( $condition ) {
                        $this->addFields( $value );

                        return true;
                }

                return false;
        }

        /**
         * Add a set of WHERE clauses to the internal array.
         * Clauses can be formatted as 'foo=bar' or [ 'foo' => 'bar' ],
         * the latter only works if the value is a constant (i.e. not another field)
         *
         * If $value is an empty array, this function does nothing.
         *
         * For example, [ 'foo=bar', 'baz' => 3, 'bla' => 'foo' ] translates
         * to "foo=bar AND baz='3' AND bla='foo'"
         * @param string|array $value
         */
        protected function addWhere( $value ) {
                if ( is_array( $value ) ) {
                        // Sanity check: don't insert empty arrays,
                        // Database::makeList() chokes on them
                        if ( count( $value ) ) {
                                $this->where = array_merge( $this->where, $value );
                        }
                } else {
                        $this->where[] = $value;
                }
        }

        /**
         * Same as addWhere(), but add the WHERE clauses only if a condition is met
         * @param string|array $value
         * @param bool $condition If false, do nothing
         * @return bool $condition
         */
        protected function addWhereIf( $value, $condition ) {
                if ( $condition ) {
                        $this->addWhere( $value );

                        return true;
                }

                return false;
        }

        /**
         * Equivalent to addWhere(array($field => $value))
         * @param string $field Field name
         * @param string|string[] $value Value; ignored if null or empty array;
         */
        protected function addWhereFld( $field, $value ) {
                // Use count() to its full documented capabilities to simultaneously
                // test for null, empty array or empty countable object
                if ( count( $value ) ) {
                        $this->where[$field] = $value;
                }
        }

        /**
         * Add a WHERE clause corresponding to a range, and an ORDER BY
         * clause to sort in the right direction
         * @param string $field Field name
         * @param string $dir If 'newer', sort in ascending order, otherwise
         *  sort in descending order
         * @param string $start Value to start the list at. If $dir == 'newer'
         *  this is the lower boundary, otherwise it's the upper boundary
         * @param string $end Value to end the list at. If $dir == 'newer' this
         *  is the upper boundary, otherwise it's the lower boundary
         * @param bool $sort If false, don't add an ORDER BY clause
         */
        protected function addWhereRange( $field, $dir, $start, $end, $sort = true ) {
                $isDirNewer = ( $dir === 'newer' );
                $after = ( $isDirNewer ? '>=' : '<=' );
                $before = ( $isDirNewer ? '<=' : '>=' );
                $db = $this->getDB();

                if ( !is_null( $start ) ) {
                        $this->addWhere( $field . $after . $db->addQuotes( $start ) );
                }

                if ( !is_null( $end ) ) {
                        $this->addWhere( $field . $before . $db->addQuotes( $end ) );
                }

                if ( $sort ) {
                        $order = $field . ( $isDirNewer ? '' : ' DESC' );
                        // Append ORDER BY
                        $optionOrderBy = isset( $this->options['ORDER BY'] )
                                ? (array)$this->options['ORDER BY']
                                : [];
                        $optionOrderBy[] = $order;
                        $this->addOption( 'ORDER BY', $optionOrderBy );
                }
        }

        /**
         * Add a WHERE clause corresponding to a range, similar to addWhereRange,
         * but converts $start and $end to database timestamps.
         * @see addWhereRange
         * @param string $field
         * @param string $dir
         * @param string $start
         * @param string $end
         * @param bool $sort
         */
        protected function addTimestampWhereRange( $field, $dir, $start, $end, $sort = true ) {
                $db = $this->getDB();
                $this->addWhereRange( $field, $dir,
                        $db->timestampOrNull( $start ), $db->timestampOrNull( $end ), $sort );
        }

        /**
         * Add an option such as LIMIT or USE INDEX. If an option was set
         * before, the old value will be overwritten
         * @param string $name Option name
         * @param string|string[] $value Option value
         */
        protected function addOption( $name, $value = null ) {
                if ( is_null( $value ) ) {
                        $this->options[] = $name;
                } else {
                        $this->options[$name] = $value;
                }
        }

        /**
         * Execute a SELECT query based on the values in the internal arrays
         * @param string $method Function the query should be attributed to.
         *  You should usually use __METHOD__ here
         * @param array $extraQuery Query data to add but not store in the object
         *  Format is [
         *    'tables' => ...,
         *    'fields' => ...,
         *    'where' => ...,
         *    'options' => ...,
         *    'join_conds' => ...
         *  ]
         * @param array|null &$hookData If set, the ApiQueryBaseBeforeQuery and
         *  ApiQueryBaseAfterQuery hooks will be called, and the
         *  ApiQueryBaseProcessRow hook will be expected.
         * @return ResultWrapper
         */
        protected function select( $method, $extraQuery = [], array &$hookData = null ) {

                $tables = array_merge(
                        $this->tables,
                        isset( $extraQuery['tables'] ) ? (array)$extraQuery['tables'] : []
                );
                $fields = array_merge(
                        $this->fields,
                        isset( $extraQuery['fields'] ) ? (array)$extraQuery['fields'] : []
                );
                $where = array_merge(
                        $this->where,
                        isset( $extraQuery['where'] ) ? (array)$extraQuery['where'] : []
                );
                $options = array_merge(
                        $this->options,
                        isset( $extraQuery['options'] ) ? (array)$extraQuery['options'] : []
                );
                $join_conds = array_merge(
                        $this->join_conds,
                        isset( $extraQuery['join_conds'] ) ? (array)$extraQuery['join_conds'] : []
                );

                if ( $hookData !== null ) {
                        Hooks::run( 'ApiQueryBaseBeforeQuery',
                                [ $this, &$tables, &$fields, &$where, &$options, &$join_conds, &$hookData ]
                        );
                }

                $res = $this->getDB()->select( $tables, $fields, $where, $method, $options, $join_conds );

                if ( $hookData !== null ) {
                        Hooks::run( 'ApiQueryBaseAfterQuery', [ $this, $res, &$hookData ] );
                }

                return $res;
        }

        /**
         * Call the ApiQueryBaseProcessRow hook
         *
         * Generally, a module that passed $hookData to self::select() will call
         * this just before calling ApiResult::addValue(), and treat a false return
         * here in the same way it treats a false return from addValue().
         *
         * @since 1.28
         * @param object $row Database row
         * @param array &$data Data to be added to the result
         * @param array &$hookData Hook data from ApiQueryBase::select()
         * @return bool Return false if row processing should end with continuation
         */
        protected function processRow( $row, array &$data, array &$hookData ) {
                return Hooks::run( 'ApiQueryBaseProcessRow', [ $this, $row, &$data, &$hookData ] );
        }

        /**
         * @param string $query
         * @param string $protocol
         * @return null|string
         */
        public function prepareUrlQuerySearchString( $query = null, $protocol = null ) {
                $db = $this->getDB();
                if ( !is_null( $query ) || $query != '' ) {
                        if ( is_null( $protocol ) ) {
                                $protocol = 'http://';
                        }

                        $likeQuery = LinkFilter::makeLikeArray( $query, $protocol );
                        if ( !$likeQuery ) {
                                $this->dieWithError( 'apierror-badquery' );
                        }

                        $likeQuery = LinkFilter::keepOneWildcard( $likeQuery );

                        return 'el_index ' . $db->buildLike( $likeQuery );
                } elseif ( !is_null( $protocol ) ) {
                        return 'el_index ' . $db->buildLike( "$protocol", $db->anyString() );
                }

                return null;
        }

        /**
         * Filters hidden users (where the user doesn't have the right to view them)
         * Also adds relevant block information
         *
         * @param bool $showBlockInfo
         * @return void
         */
        public function showHiddenUsersAddBlockInfo( $showBlockInfo ) {
                $this->addTables( 'ipblocks' );
                $this->addJoinConds( [
                        'ipblocks' => [ 'LEFT JOIN', 'ipb_user=user_id' ],
                ] );

                $this->addFields( 'ipb_deleted' );

                if ( $showBlockInfo ) {
                        $this->addFields( [
                                'ipb_id',
                                'ipb_by',
                                'ipb_by_text',
                                'ipb_reason',
                                'ipb_expiry',
                                'ipb_timestamp'
                        ] );
                }

                // Don't show hidden names
                if ( !$this->getUser()->isAllowed( 'hideuser' ) ) {
                        $this->addWhere( 'ipb_deleted = 0 OR ipb_deleted IS NULL' );
                }
        }

        /**@}*/

        /************************************************************************//**
         * @name   Utility methods
         * @{
         */

        /**
         * Add information (title and namespace) about a Title object to a
         * result array
         * @param array $arr Result array à la ApiResult
         * @param Title $title
         * @param string $prefix Module prefix
         */
        public static function addTitleInfo( &$arr, $title, $prefix = '' ) {
                $arr[$prefix . 'ns'] = intval( $title->getNamespace() );
                $arr[$prefix . 'title'] = $title->getPrefixedText();
        }

        /**
         * Add a sub-element under the page element with the given page ID
         * @param int $pageId Page ID
         * @param array $data Data array à la ApiResult
         * @return bool Whether the element fit in the result
         */
        protected function addPageSubItems( $pageId, $data ) {
                $result = $this->getResult();
                ApiResult::setIndexedTagName( $data, $this->getModulePrefix() );

                return $result->addValue( [ 'query', 'pages', intval( $pageId ) ],
                        $this->getModuleName(),
                        $data );
        }

        /**
         * Same as addPageSubItems(), but one element of $data at a time
         * @param int $pageId Page ID
         * @param array $item Data array à la ApiResult
         * @param string $elemname XML element name. If null, getModuleName()
         *  is used
         * @return bool Whether the element fit in the result
         */
        protected function addPageSubItem( $pageId, $item, $elemname = null ) {
                if ( is_null( $elemname ) ) {
                        $elemname = $this->getModulePrefix();
                }
                $result = $this->getResult();
                $fit = $result->addValue( [ 'query', 'pages', $pageId,
                        $this->getModuleName() ], null, $item );
                if ( !$fit ) {
                        return false;
                }
                $result->addIndexedTagName( [ 'query', 'pages', $pageId,
                        $this->getModuleName() ], $elemname );

                return true;
        }

        /**
         * Set a query-continue value
         * @param string $paramName Parameter name
         * @param string|array $paramValue Parameter value
         */
        protected function setContinueEnumParameter( $paramName, $paramValue ) {
                $this->getContinuationManager()->addContinueParam( $this, $paramName, $paramValue );
        }

        /**
         * Convert an input title or title prefix into a dbkey.
         *
         * $namespace should always be specified in order to handle per-namespace
         * capitalization settings.
         *
         * @param string $titlePart Title part
         * @param int $namespace Namespace of the title
         * @return string DBkey (no namespace prefix)
         */
        public function titlePartToKey( $titlePart, $namespace = NS_MAIN ) {
                $t = Title::makeTitleSafe( $namespace, $titlePart . 'x' );
                if ( !$t || $t->hasFragment() ) {
                        // Invalid title (e.g. bad chars) or contained a '#'.
                        $this->dieWithError( [ 'apierror-invalidtitle', wfEscapeWikiText( $titlePart ) ] );
                }
                if ( $namespace != $t->getNamespace() || $t->isExternal() ) {
                        // This can happen in two cases. First, if you call titlePartToKey with a title part
                        // that looks like a namespace, but with $defaultNamespace = NS_MAIN. It would be very
                        // difficult to handle such a case. Such cases cannot exist and are therefore treated
                        // as invalid user input. The second case is when somebody specifies a title interwiki
                        // prefix.
                        $this->dieWithError( [ 'apierror-invalidtitle', wfEscapeWikiText( $titlePart ) ] );
                }

                return substr( $t->getDBkey(), 0, -1 );
        }

        /**
         * Convert an input title or title prefix into a namespace constant and dbkey.
         *
         * @since 1.26
         * @param string $titlePart Title part
         * @param int $defaultNamespace Default namespace if none is given
         * @return array (int, string) Namespace number and DBkey
         */
        public function prefixedTitlePartToKey( $titlePart, $defaultNamespace = NS_MAIN ) {
                $t = Title::newFromText( $titlePart . 'x', $defaultNamespace );
                if ( !$t || $t->hasFragment() || $t->isExternal() ) {
                        // Invalid title (e.g. bad chars) or contained a '#'.
                        $this->dieWithError( [ 'apierror-invalidtitle', wfEscapeWikiText( $titlePart ) ] );
                }

                return [ $t->getNamespace(), substr( $t->getDBkey(), 0, -1 ) ];
        }

        /**
         * @param string $hash
         * @return bool
         */
        public function validateSha1Hash( $hash ) {
                return (bool)preg_match( '/^[a-f0-9]{40}$/', $hash );
        }

        /**
         * @param string $hash
         * @return bool
         */
        public function validateSha1Base36Hash( $hash ) {
                return (bool)preg_match( '/^[a-z0-9]{31}$/', $hash );
        }

        /**
         * Check whether the current user has permission to view revision-deleted
         * fields.
         * @return bool
         */
        public function userCanSeeRevDel() {
                return $this->getUser()->isAllowedAny(
                        'deletedhistory',
                        'deletedtext',
                        'suppressrevision',
                        'viewsuppressed'
                );
        }

        /**@}*/
}