<?php
// SPDX-License-Identifier: GPL-3.0-or-later
declare(strict_types=1);

namespace Aiwend\Knowledge;

use Aiwend\Db\Connection;
use Aiwend\Support\Clock;

/**
 * Physically removes a deleted source's local derivatives: chunks (text and
 * vectors), versions and bot links. Citations already shown in past answers
 * keep their number but lose title and link. The source row stays as a
 * content-free tombstone (status "deleted") so deletion is traceable.
 *
 * This covers local data only. Copies held by an external provider are
 * tracked separately once real providers exist.
 */
final class Purger
{
    public function __construct(private Connection $db, private Clock $clock)
    {
    }

    /** @return array{chunks:int, versions:int} */
    public function purge(int $siteId, int $sourceId): array
    {
        return $this->db->transaction(function () use ($siteId, $sourceId): array {
            $row = $this->db->selectOne('SELECT status FROM {knowledge_sources} WHERE id = ? AND site_id = ?', [$sourceId, $siteId]);
            if ($row === null || !in_array($row['status'], ['deleting', 'deleted'], true)) {
                return ['chunks' => 0, 'versions' => 0];
            }
            $chunks = $this->db->execute('DELETE FROM {knowledge_chunks} WHERE source_id = ? AND site_id = ?', [$sourceId, $siteId]);
            $versions = $this->db->execute('DELETE FROM {knowledge_versions} WHERE source_id = ? AND site_id = ?', [$sourceId, $siteId]);
            $this->db->execute('DELETE FROM {knowledge_claims} WHERE source_id = ? AND site_id = ?', [$sourceId, $siteId]);
            $this->db->execute('DELETE FROM {bot_sources} WHERE source_id = ? AND site_id = ?', [$sourceId, $siteId]);
            $this->db->execute('DELETE FROM {knowledge_blobs} WHERE source_id = ? AND site_id = ?', [$sourceId, $siteId]);
            $this->db->execute("UPDATE {message_citations} SET title = '[deleted source]', url = NULL WHERE source_id = ? AND site_id = ?", [$sourceId, $siteId]);
            $this->db->execute(
                "UPDATE {knowledge_sources} SET status = 'deleted', title = '[deleted]', url = NULL, origin_ref = ?, current_version_id = NULL, error = NULL, updated_at = ? WHERE id = ? AND site_id = ?",
                ['deleted:' . $sourceId, $this->clock->now(), $sourceId, $siteId]
            );
            return ['chunks' => $chunks, 'versions' => $versions];
        });
    }
}