<?php

namespace Modules\Communication\Services;

use App\User;

class LiveKitTokenService
{
    public function createToken(
        User $user,
        string $roomName,
        bool $isHost = false,
        ?string $language = null,
        bool $translationEnabled = false,
    ): string {
        $apiKey = config('livekit.api_key');
        $apiSecret = config('livekit.api_secret');
        $language = $this->normalizeLanguage($language);

        $now = time();
        $identity = (string) $user->id;
        $payload = [
            'iss' => $apiKey,
            'sub' => $identity,
            'jti' => $identity,
            'name' => $user->user_full_name ?: $user->first_name,
            'nbf' => $now,
            'iat' => $now,
            'exp' => $now + 3600,
            'attributes' => [
                'lang' => $language,
                'language' => $language,
                'translation' => $translationEnabled ? 'true' : 'false',
            ],
            'video' => array_filter([
                'room' => $roomName,
                'roomJoin' => true,
                'canPublish' => true,
                'canSubscribe' => true,
                'roomAdmin' => $isHost ? true : null,
            ]),
        ];

        if ($translationEnabled) {
            $payload['roomConfig'] = [
                'agents' => [
                    ['agentName' => config('livekit.translator_agent', 'translator')],
                ],
            ];
        }

        return $this->encodeJwt($payload, $apiSecret);
    }

    public function getUrl(): string
    {
        return config('livekit.url');
    }

    public function normalizeLanguage(?string $language): string
    {
        $languages = array_keys(config('communication.translation_languages', ['fa' => 'فارسی', 'en' => 'English']));
        $default = config('communication.default_meeting_language', 'fa');

        if ($language && in_array($language, $languages, true)) {
            return $language;
        }

        return in_array($default, $languages, true) ? $default : 'en';
    }

    private function encodeJwt(array $payload, string $secret): string
    {
        $header = ['typ' => 'JWT', 'alg' => 'HS256'];
        $segments = [
            $this->base64UrlEncode(json_encode($header)),
            $this->base64UrlEncode(json_encode($payload)),
        ];
        $signature = hash_hmac('sha256', implode('.', $segments), $secret, true);
        $segments[] = $this->base64UrlEncode($signature);

        return implode('.', $segments);
    }

    private function base64UrlEncode(string $data): string
    {
        return rtrim(strtr(base64_encode($data), '+/', '-_'), '=');
    }
}