<?php declare(strict_types=1);
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

namespace Magento\Eav\Model\Mview\ChangelogBatchWalker;

use Magento\Framework\App\ResourceConnection;
use Magento\Framework\DB\Select;
use Magento\Framework\DB\Sql\Expression;
use Magento\Framework\Mview\View\ChangelogBatchWalker\IdsSelectBuilderInterface;
use Magento\Framework\Mview\View\ChangelogInterface;

class IdsSelectBuilder implements IdsSelectBuilderInterface
{
    private const GROUP_CONCAT_MAX_VARIABLE = 'group_concat_max_len';
    /** ID is defined as small int. Default size of it is 5 */
    private const DEFAULT_ID_SIZE = 5;
    /**
     * @var \Magento\Framework\App\ResourceConnection
     */
    private ResourceConnection $resourceConnection;
    /**
     * @var array
     */
    private array $entityTypeCodes;

    /**
     * @param \Magento\Framework\App\ResourceConnection $resourceConnection
     * @param array $entityTypeCodes
     */
    public function __construct(
        ResourceConnection $resourceConnection,
        array              $entityTypeCodes = []
    ) {
        $this->resourceConnection = $resourceConnection;
        $this->entityTypeCodes = $entityTypeCodes;
    }

    /**
     * @inheritdoc
     */
    public function build(ChangelogInterface $changelog): Select
    {
        $numberOfAttributes = $this->calculateEavAttributeSize($changelog);
        $this->setGroupConcatMax($numberOfAttributes);

        $changelogTableName = $this->resourceConnection->getTableName($changelog->getName());

        $connection = $this->resourceConnection->getConnection();

        $columns = [
            $changelog->getColumnName(),
            'attribute_ids' => new Expression('GROUP_CONCAT(attribute_id)'),
            'store_id'
        ];

        return $connection->select()
            ->from($changelogTableName, $columns)
            ->group([$changelog->getColumnName(), 'store_id']);
    }

    /**
     * Calculate EAV attributes size
     *
     * @param ChangelogInterface $changelog
     * @return int
     * @throws \Exception
     */
    private function calculateEavAttributeSize(ChangelogInterface $changelog): int
    {
        $connection = $this->resourceConnection->getConnection();

        if (!isset($this->entityTypeCodes[$changelog->getViewId()])) {
            throw new \InvalidArgumentException('Entity type for view was not defined');
        }

        $select = $connection->select();
        $select->from(
            $this->resourceConnection->getTableName('eav_attribute'),
            new Expression('COUNT(*)')
        )
            ->joinInner(
                ['type' => $connection->getTableName('eav_entity_type')],
                'type.entity_type_id=eav_attribute.entity_type_id'
            )
            ->where('type.entity_type_code = ?', $this->entityTypeCodes[$changelog->getViewId()]);

        return (int)$connection->fetchOne($select);
    }

    /**
     * Prepare group max concat
     *
     * @param int $numberOfAttributes
     * @return void
     * @throws \Exception
     */
    private function setGroupConcatMax(int $numberOfAttributes): void
    {
        $connection = $this->resourceConnection->getConnection();
        $connection->query(sprintf(
            'SET SESSION %s=%s',
            self::GROUP_CONCAT_MAX_VARIABLE,
            $numberOfAttributes * (self::DEFAULT_ID_SIZE + 1)
        ));
    }
}