<?php
/**
 * Updates database rows by primary key in batches.
 *
 * 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
 * @ingroup Maintenance
 */

use MediaWiki\MediaWikiServices;
use Wikimedia\Rdbms\IDatabase;

class BatchRowWriter {
	/**
	 * @var IDatabase The database to write to
	 */
	protected $db;

	/**
	 * @var string The name of the table to update
	 */
	protected $table;

	/**
	 * @var string|false A cluster name valid for use with LBFactory
	 */
	protected $clusterName;

	/**
	 * @var string|null For debugging which method is using this class.
	 */
	protected $caller;

	/**
	 * @param IDatabase $db The database to write to
	 * @param string $table The name of the table to update
	 * @param string|false $clusterName A cluster name valid for use with LBFactory
	 */
	public function __construct( IDatabase $db, $table, $clusterName = false ) {
		$this->db = $db;
		$this->table = $table;
		$this->clusterName = $clusterName;
	}

	/**
	 * Use ->setCaller( __METHOD__ ) to indicate which code is using this
	 * class. Only used in debugging output.
	 * @since 1.36
	 *
	 * @param string $caller
	 * @return self
	 */
	public function setCaller( $caller ) {
		$this->caller = $caller;
		return $this;
	}

	/**
	 * @param array[][] $updates Array of arrays each containing two keys, 'primaryKey'
	 *  and 'changes'. primaryKey must contain a map of column names to values
	 *  sufficient to uniquely identify the row. changes must contain a map of column
	 *  names to update values to apply to the row.
	 * @phan-param array<int,array{primaryKey:array,changes:array}> $updates
	 */
	public function write( array $updates ) {
		$dbProvider = MediaWikiServices::getInstance()->getConnectionProvider();
		$ticket = $dbProvider->getEmptyTransactionTicket( __METHOD__ );

		$caller = __METHOD__;
		if ( (string)$this->caller !== '' ) {
			$caller .= " (for {$this->caller})";
		}

		foreach ( $updates as $update ) {
			$this->db->newUpdateQueryBuilder()
				->update( $this->table )
				->set( $update['changes'] )
				->where( $update['primaryKey'] )
				->caller( $caller )->execute();
		}

		$dbProvider->commitAndWaitForReplication( __METHOD__, $ticket );
	}
}