<?php

namespace App\Integrations\Whmcs\Support;

use Illuminate\Support\Facades\DB;

/**
 * Resolves a WHMCS `tblclients.id` to the matching local `customers.id`,
 * bridged through the uuid both sides already share (see ClientWriter).
 */
class CustomerIdResolver
{
    /** @var array<int, int>|null whmcs client id => local customer id */
    private static ?array $map = null;

    public function resolve(int $whmcsClientId): ?int
    {
        self::$map ??= $this->build();

        return self::$map[$whmcsClientId] ?? null;
    }

    private function build(): array
    {
        $uuidsByWhmcsId = DB::connection('whmcs')->table('tblclients')->pluck('uuid', 'id');
        $customerIdsByUuid = DB::table('customers')->pluck('id', 'uuid');

        $map = [];
        foreach ($uuidsByWhmcsId as $whmcsId => $uuid) {
            if (isset($customerIdsByUuid[$uuid])) {
                $map[$whmcsId] = $customerIdsByUuid[$uuid];
            }
        }

        return $map;
    }
}