<?php

declare(strict_types=1);

namespace LIT\MCP\Integrations\WordPress\Schema;

defined('ABSPATH') || exit;

/**
 * Meta keys actually used by the most recent posts of a type. Keys starting with
 * "_" are internal and only shown when another source knows them.
 */
final class SampledMetaSource extends MetaFieldSource
{
    private const SAMPLE_POSTS = 50;
    private const MAX_KEYS = 200;

    /** @param bool $readOnly Report the keys as READONLY (Pods is active but cannot be used to write them). */
    public function __construct(private ?\wpdb $db = null, private bool $readOnly = false)
    {
    }

    public function id(): string
    {
        return 'sample';
    }

    public function fieldsFor(string $postType): array
    {
        $wpdb = $this->db ?? $GLOBALS['wpdb'];
        // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- only core table names interpolated.
        $keys = $wpdb->get_col($wpdb->prepare(
            "SELECT DISTINCT pm.meta_key FROM {$wpdb->postmeta} pm
             INNER JOIN (
                SELECT ID FROM {$wpdb->posts}
                WHERE post_type = %s AND post_status NOT IN ('auto-draft', 'trash')
                ORDER BY ID DESC LIMIT %d
             ) recent ON recent.ID = pm.post_id
             ORDER BY pm.meta_key LIMIT %d",
            $postType,
            self::SAMPLE_POSTS,
            self::MAX_KEYS
        ));

        $fields = [];
        foreach ((array) $keys as $key) {
            $key = (string) $key;
            if ($key === '' || str_starts_with($key, '_')) {
                continue;
            }

            $fields[] = new FieldDefinition(
                $key,
                $key,
                'unknown',
                'sample',
                $this->readOnly ? FieldDefinition::READONLY : FieldDefinition::UNKNOWN
            );
        }

        return $fields;
    }
}