<?php

namespace App\Integrations\Whmcs\Support;

use Illuminate\Support\Facades\DB;

/**
 * Resolves a WHMCS `tblclients.id` to the matching local `customers.id`: by the uuid both
 * sides share (see ClientWriter), falling back to email for customers that already existed
 * on the portal with a different uuid.
 */
class CustomerIdResolver
{
    /** @var array<int, int>|null whmcs client id => local customer id */
    private static ?array $map = null;

    /** @var array<int, true>|null whmcs client ids that exist in tblclients */
    private static ?array $known = null;

    public function __construct(private SyncReport $report)
    {
    }

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

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

    public function resolveFor(string $entity, string|int $ref, int $whmcsClientId): ?int
    {
        $customerId = $this->resolve($whmcsClientId);

        if ($customerId === null) {
            $exists = isset(self::$known[$whmcsClientId]);
            $this->report->note(
                $entity,
                (string) $ref,
                $whmcsClientId,
                $exists ? 'khach_chua_co_tren_portal' : 'khach_khong_ton_tai_trong_whmcs',
                $exists
                    ? "Khách WHMCS #{$whmcsClientId} chưa có tài khoản portal khớp uuid/email — bỏ qua {$entity}."
                    : "Khách WHMCS #{$whmcsClientId} không còn trong tblclients (đã xoá) — bỏ qua {$entity}.",
            );
        }

        return $customerId;
    }

    public function resolveDomainOwner(string $domain, int $whmcsClientId): ?int
    {
        $customerId = $this->resolve($whmcsClientId);
        if ($customerId !== null) {
            return $customerId;
        }

        $name = mb_strtolower(trim($domain));
        $whmcs = DB::connection('whmcs');

        $holderClientId = $whmcs->table('tbldomains as d')
            ->join('tblclients as c', 'c.id', '=', 'd.userid')
            ->whereRaw('LOWER(TRIM(d.domain)) = ?', [$name])
            ->orderByRaw("d.status = 'Active' DESC")
            ->orderByDesc('d.id')
            ->value('d.userid');
        if ($holderClientId && ($customerId = $this->resolve((int) $holderClientId)) !== null) {
            return $this->traced($name, $whmcsClientId, $customerId, 'domain_cung_ten_khach_khac', "Tên miền cùng tên đang do khách WHMCS #{$holderClientId} giữ.");
        }

        $linkedCustomerId = DB::table('dns_domain_user as l')
            ->join('dns_manager_domain as d', 'd.id', '=', 'l.domain_id')
            ->whereRaw('LOWER(d.domain_name) = ?', [$name])
            ->orderBy('l.id')
            ->value('l.user_id');
        if ($linkedCustomerId) {
            return $this->traced($name, $whmcsClientId, (int) $linkedCustomerId, 'domain_da_gan_khach_trong_dns', 'Tên miền đã gắn khách trong DNS Manager của portal.');
        }

        $contactEmails = $whmcs->table('tblcontacts')->where('userid', $whmcsClientId)->pluck('email')->map(fn ($email) => strtolower((string) $email))->filter()->all();
        if ($contactEmails !== [] && ($customerId = DB::table('customers')->whereIn(DB::raw('LOWER(email)'), $contactEmails)->value('id'))) {
            return $this->traced($name, $whmcsClientId, (int) $customerId, 'domain_khop_email_lien_he', 'Khớp theo email liên hệ của khách đã xoá.');
        }

        $this->report->note(
            'domain',
            $name,
            $whmcsClientId,
            'khach_khong_ton_tai_trong_whmcs',
            "Khách WHMCS #{$whmcsClientId} đã xoá, không suy ra được chủ. Email liên hệ còn lại: " . ($contactEmails ? implode(', ', $contactEmails) : 'không có'),
        );

        return null;
    }

    private function traced(string $domain, int $whmcsClientId, int $customerId, string $issue, string $detail): int
    {
        $this->report->note('domain', $domain, $whmcsClientId, $issue, "Khách WHMCS #{$whmcsClientId} đã xoá; chủ suy ra → khách portal #{$customerId}. {$detail}");

        return $customerId;
    }

    public static function flush(): void
    {
        self::$map = null;
        self::$known = null;
    }

    private function build(): array
    {
        $clients = DB::connection('whmcs')->table('tblclients')->get(['id', 'uuid', 'email']);
        $byUuid = DB::table('customers')->pluck('id', 'uuid');
        $byEmail = DB::table('customers')->whereNotNull('email')->pluck('id', DB::raw('LOWER(email)'));

        $map = [];
        self::$known = [];
        foreach ($clients as $client) {
            self::$known[$client->id] = true;
            $customerId = $byUuid[$client->uuid] ?? $byEmail[strtolower((string) $client->email)] ?? null;
            if ($customerId !== null) {
                $map[$client->id] = $customerId;
            }
        }

        return $map;
    }
}