<?php
/**
 * A central user id lookup service implementation
 *
 * 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
 */

use MediaWiki\MainConfigNames;
use MediaWiki\User\UserIdentity;
use MediaWiki\WikiMap\WikiMap;
use Wikimedia\Rdbms\ILoadBalancer;

/**
 * A CentralIdLookup provider that just uses local IDs. Useful if the wiki
 * isn't part of a cluster or you're using shared user tables.
 *
 * @note Shared user table support expects that all wikis involved have
 *  $wgSharedDB and $wgSharedTables set, and that all wikis involved in the
 *  sharing are listed in $wgLocalDatabases, and that no wikis not involved in
 *  the sharing are listed in $wgLocalDatabases.
 * @since 1.27
 */
class LocalIdLookup extends CentralIdLookup {

	/** @var ILoadBalancer */
	private $loadBalancer;

	/** @var string|null */
	private $sharedDB;

	/** @var string[] */
	private $sharedTables;

	/** @var string[] */
	private $localDatabases;

	/**
	 * @param Config $config
	 * @param ILoadBalancer $loadBalancer
	 */
	public function __construct(
		Config $config,
		ILoadBalancer $loadBalancer
	) {
		$this->sharedDB = $config->get( MainConfigNames::SharedDB );
		$this->sharedTables = $config->get( MainConfigNames::SharedTables );
		$this->localDatabases = $config->get( MainConfigNames::LocalDatabases );
		$this->loadBalancer = $loadBalancer;
	}

	public function isAttached( UserIdentity $user, $wikiId = UserIdentity::LOCAL ): bool {
		// If the user has no ID, it can't be attached
		if ( !$user->isRegistered() ) {
			return false;
		}

		// Easy case, we're checking locally
		if ( !$wikiId || WikiMap::isCurrentWikiId( $wikiId ) ) {
			return true;
		}

		// Assume that shared user tables are set up as described above, if
		// they're being used at all.
		return $this->sharedDB !== null &&
			in_array( 'user', $this->sharedTables, true ) &&
			in_array( $wikiId, $this->localDatabases, true );
	}

	public function lookupCentralIds(
		array $idToName, $audience = self::AUDIENCE_PUBLIC, $flags = self::READ_NORMAL
	): array {
		if ( !$idToName ) {
			return [];
		}
		$audience = $this->checkAudience( $audience );
		[ $index, $options ] = DBAccessObjectUtils::getDBOptions( $flags );
		$db = $this->loadBalancer->getConnectionRef( $index );

		$tables = [ 'user' ];
		$fields = [ 'user_id', 'user_name' ];
		$where = [
			'user_id' => array_map( 'intval', array_keys( $idToName ) ),
		];
		$join = [];
		if ( $audience && !$audience->isAllowed( 'hideuser' ) ) {
			$tables[] = 'ipblocks';
			$join['ipblocks'] = [ 'LEFT JOIN', 'ipb_user=user_id' ];
			$fields[] = 'ipb_deleted';
		}

		$res = $db->select( $tables, $fields, $where, __METHOD__, $options, $join );
		foreach ( $res as $row ) {
			$idToName[$row->user_id] = empty( $row->ipb_deleted ) ? $row->user_name : '';
		}

		return $idToName;
	}

	public function lookupUserNames(
		array $nameToId, $audience = self::AUDIENCE_PUBLIC, $flags = self::READ_NORMAL
	): array {
		if ( !$nameToId ) {
			return [];
		}

		$audience = $this->checkAudience( $audience );
		[ $index, $options ] = DBAccessObjectUtils::getDBOptions( $flags );
		$db = $this->loadBalancer->getConnectionRef( $index );

		$tables = [ 'user' ];
		$fields = [ 'user_id', 'user_name' ];
		$where = [
			'user_name' => array_map( 'strval', array_keys( $nameToId ) ),
		];
		$join = [];
		if ( $audience && !$audience->isAllowed( 'hideuser' ) ) {
			$tables[] = 'ipblocks';
			$join['ipblocks'] = [ 'LEFT JOIN', 'ipb_user=user_id' ];
			$where[] = 'ipb_deleted = 0 OR ipb_deleted IS NULL';
		}

		$res = $db->select( $tables, $fields, $where, __METHOD__, $options, $join );
		foreach ( $res as $row ) {
			$nameToId[$row->user_name] = (int)$row->user_id;
		}

		return $nameToId;
	}
}
