<?php

namespace App\Services;

use App\Models\GameAccount;
use Carbon\CarbonImmutable;
use Illuminate\Support\Facades\DB;
use RuntimeException;

class LauncherGameTicketService
{
    private const string ALPHABET = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';

    private const int TICKET_LENGTH = 16;

    public function __construct(private readonly AzerothCoreSrpService $srp) {}

    /**
     * @return array{account: string, ticket: string, expires_at: string}
     */
    public function issue(GameAccount $account, string $launcherSessionToken, int $clientBuild): array
    {
        $username = $this->srp->normalizeUsername((string) $account->username);
        $this->assertCompatibleAccountName($username);

        $ticket = $this->randomTicket();
        [$saltHex, $verifierHex] = $this->srp->makeRegistrationData($username, $ticket);
        $generationId = random_bytes(16);
        $sessionHash = hash('sha256', $launcherSessionToken, true);
        $issuedAt = CarbonImmutable::now('UTC');
        $ttl = max(5, min(60, (int) config('moonwell.launcher.game_ticket_ttl', 60)));
        $expiresAt = $issuedAt->addSeconds($ttl);
        $connection = DB::connection((string) config('moonwell.auth_connection'));

        $connection->transaction(function () use (
            $connection,
            $account,
            $generationId,
            $saltHex,
            $verifierHex,
            $clientBuild,
            $sessionHash,
            $issuedAt,
            $expiresAt,
        ): void {
            $connection->table('launcher_ticket')->updateOrInsert(
                ['account_id' => (int) $account->id],
                [
                    'generation_id' => $generationId,
                    'srp_salt' => hex2bin($saltHex),
                    'srp_verifier' => hex2bin($verifierHex),
                    'client_build' => $clientBuild,
                    'launcher_session_hash' => $sessionHash,
                    'issued_at' => $issuedAt,
                    'expires_at' => $expiresAt,
                ],
            );
        });

        return [
            'account' => $username,
            'ticket' => $ticket,
            'expires_at' => $expiresAt->format('Y-m-d\\TH:i:s\\Z'),
        ];
    }

    private function randomTicket(): string
    {
        $ticket = '';
        $lastIndex = strlen(self::ALPHABET) - 1;

        for ($i = 0; $i < self::TICKET_LENGTH; $i++) {
            $ticket .= self::ALPHABET[random_int(0, $lastIndex)];
        }

        return $ticket;
    }

    private function assertCompatibleAccountName(string $username): void
    {
        if (
            $username === ''
            || strlen($username) > 17
            || preg_match('/^[!-<>-~]+$/D', $username) !== 1
        ) {
            throw new RuntimeException('Game account is not compatible with the 3.3.5a authentication protocol.');
        }
    }
}