<?php

declare(strict_types=1);

/*
 * Chill is a software for social workers
 *
 * For the full copyright and license information, please view
 * the LICENSE file that was distributed with this source code.
 */

namespace Chill\PersonBundle\Service\AccompanyingPeriodWork;

use Chill\PersonBundle\Entity\AccompanyingPeriod\AccompanyingPeriodWork;
use Doctrine\DBAL\Exception;
use Doctrine\ORM\EntityManagerInterface;
use Doctrine\ORM\Mapping\ClassMetadata;

class AccompanyingPeriodWorkMergeService
{
    public function __construct(private readonly EntityManagerInterface $em) {}

    /**
     * @throws Exception
     */
    public function merge(AccompanyingPeriodWork $toKeep, AccompanyingPeriodWork $toDelete): void
    {
        // Transfer non-duplicate data
        $this->transferData($toKeep, $toDelete);

        // Update linked entities
        $this->updateReferences($toKeep, $toDelete);

        $this->em->remove($toDelete);
        $this->em->flush();
    }

    /**
     * @throws Exception
     */
    private function transferData(AccompanyingPeriodWork $toKeep, AccompanyingPeriodWork $toDelete): void
    {
        $conn = $this->em->getConnection();

        $sqlStatements = [
            $this->generateStartDateSQL(),
            $this->generateEndDateSQL(),
            $this->generateCommentSQL(),
        ];

        $conn->beginTransaction();

        try {
            foreach ($sqlStatements as $sql) {
                $conn->executeQuery($sql, ['toDelete' => $toDelete->getId(), 'toKeep' => $toKeep->getId()]);
            }
            $conn->commit();
        } catch (\Exception $e) {
            $conn->rollBack();
            throw $e;
        }
    }

    private function generateStartDateSQL(): string
    {
        return '
            UPDATE chill_person_accompanying_period_work
            SET startdate = LEAST(
                COALESCE((SELECT startdate FROM chill_person_accompanying_period_work WHERE id = :toDelete), startdate),
                startdate
            )
            WHERE id = :toKeep';
    }

    private function generateEndDateSQL(): string
    {
        return '
            UPDATE chill_person_accompanying_period_work
            SET enddate =
                CASE
                    WHEN (SELECT enddate FROM chill_person_accompanying_period_work WHERE id = :toDelete) IS NULL
                        OR enddate IS NULL
                    THEN NULL
                    ELSE GREATEST(
                        COALESCE((SELECT enddate FROM chill_person_accompanying_period_work WHERE id = :toDelete), enddate),
                        enddate
                    )
                END
            WHERE id = :toKeep';
    }

    private function generateCommentSQL(): string
    {
        return "
            UPDATE chill_person_accompanying_period_work
            SET note = CONCAT_WS(
                '\n',
                NULLIF(TRIM(note), ''),
                NULLIF(TRIM((SELECT note FROM chill_person_accompanying_period_work WHERE id = :toDelete)), '')
            )
            WHERE id = :toKeep";
    }

    /**
     * @throws Exception
     */
    private function updateReferences(AccompanyingPeriodWork $toKeep, AccompanyingPeriodWork $toDelete): void
    {
        $allMeta = $this->em->getMetadataFactory()->getAllMetadata();
        $conn = $this->em->getConnection();
        $sqlStatements = [];

        foreach ($allMeta as $meta) {
            if ($meta->isMappedSuperclass) {
                continue;
            }

            foreach ($meta->getAssociationMappings() as $assoc) {
                if (AccompanyingPeriodWork::class !== $assoc['targetEntity']) {
                    continue;
                }

                if ($assoc['type'] & ClassMetadata::TO_ONE) {
                    if ('handlingThirdparty' === $assoc['fieldName']) {
                        continue;
                    }
                    $sqlStatements[] = $this->generateToOneUpdateQuery($meta, $assoc);
                }

                if ($assoc['type'] & ClassMetadata::TO_MANY) {
                    if (!isset($assoc['joinTable'])) {
                        continue;
                    }
                    $sqlStatements = array_merge($sqlStatements, $this->generateToManyUpdateQueries($assoc));
                }
            }
        }

        $conn->beginTransaction();
        try {
            foreach ($sqlStatements as $sql) {
                $conn->executeStatement($sql, ['toDelete' => $toDelete->getId(), 'toKeep' => $toKeep->getId()]);
            }
            $conn->commit();
        } catch (\Exception $e) {
            $conn->rollBack();
            throw $e;
        }
    }

    private function generateToOneUpdateQuery(ClassMetadata $meta, array $assoc): string
    {
        $tableName = $meta->getTableName();
        $joinColumn = $meta->getSingleAssociationJoinColumnName($assoc['fieldName']);

        return "UPDATE {$tableName} SET {$joinColumn} = :toKeep WHERE {$joinColumn} = :toDelete";
    }

    private function generateToManyUpdateQueries(array $assoc): array
    {
        $sqls = [];
        $joinTable = $assoc['joinTable']['name'];
        $owningColumn = $assoc['joinTable']['joinColumns'][0]['name'];
        $inverseColumn = $assoc['joinTable']['inverseJoinColumns'][0]['name'];

        // Insert relations, skip already existing ones
        $sqls[] = "INSERT IGNORE INTO {$joinTable} ({$owningColumn}, {$inverseColumn})
                SELECT :toKeep, {$inverseColumn} FROM {$joinTable} WHERE {$owningColumn} = :toDelete";
        // Delete old references
        $sqls[] = "DELETE FROM {$joinTable} WHERE {$owningColumn} = :toDelete";

        return $sqls;
    }
}