<?php
/**
* Copyright © Magento, Inc. All rights reserved.
* See COPYING.txt for license details.
*/
namespace Magento\Framework\DB;

use Magento\Framework\App\ResourceConnection;
use Magento\Framework\DB\Adapter\AdapterInterface;

/**
* Class Concat
*/
class SubSelect extends \Zend_Db_Expr
{
/**
* @var string
*/
protected $table;

/**
* @var string[]
*/
protected $columns;

/**
* @var string
*/
protected $originColumn;

/**
* @var string
*/
protected $targetColumn;

/**
* @var \Magento\Framework\App\ResourceConnection
*/
protected $resource;

/**
* @var string
*/
protected $connectionName;

/**
* @var AdapterInterface
*/
protected $connection;

/**
* @param ResourceConnection $resource
* @param string $connectionName
* @param string $table
* @param string[] $columns
* @param string $originColumn
* @param string $targetColumn
*/
public function __construct(
ResourceConnection $resource,
$table,
array $columns,
$originColumn,
$targetColumn,
$connectionName = ResourceConnection::DEFAULT_CONNECTION
) {
$this->resource = $resource;
$this->connectionName = $connectionName;
$this->table = $table;
$this->columns = $columns;
$this->originColumn = $originColumn;
$this->targetColumn = $targetColumn;
}

/**
* @return string
*/
public function __toString()
{
$select = $this->getConnection()->select()->from(
$this->resource->getTableName($this->table),
array_values($this->columns)
)->where(
sprintf(
'%s = %s',
$this->getConnection()->quoteIdentifier($this->originColumn),
$this->getConnection()->quoteIdentifier($this->targetColumn)
)
)->limit(1);
return sprintf('(%s)', $select);
}

/**
* Returns connection
*
* @return AdapterInterface
*/
protected function getConnection()
{
if (!$this->connection) {
$this->connection = $this->resource->getConnection($this->connectionName);
}
return $this->connection;
}
}