<?php

declare(strict_types=1);

namespace App\Services;

use App\Models\GoogleOAuthConnection;
use App\Enums\GoogleService;
use Google_Client;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Log;

class GoogleOAuthService
{
    private const TOKEN_CACHE_TTL = 300;
    private const MAX_RETRIES = 2;

    public function buildClient(): Google_Client
    {
        $client = new Google_Client();
        $client->setClientId(config('services.google.client_id'));
        $client->setClientSecret(config('services.google.client_secret'));
        $client->setRedirectUri(route('google-oauth.callback'));
        $client->setAccessType('offline');
        $client->setPrompt('consent');
        $client->setIncludeGrantedScopes(true);

        return $client;
    }

    public function getAuthUrl(string $service): string
    {
        $serviceEnum = GoogleService::from($service);
        $client = $this->buildClient();
        $client->setScopes($serviceEnum->scopes());
        $client->setState($service);

        return $client->createAuthUrl();
    }

    public function handleCallback(string $authorizationCode, GoogleService $service): GoogleOAuthConnection
    {
        $client = $this->buildClient();
        $client->setScopes($service->scopes());
        $client->fetchAccessTokenWithAuthCode($authorizationCode);

        $tokenData = $client->getAccessToken();

        if (isset($tokenData['error'])) {
            throw new \RuntimeException('Google OAuth error: ' . ($tokenData['error_description'] ?? $tokenData['error']));
        }

        $token = $tokenData['access_token'];
        $refreshToken = $tokenData['refresh_token'] ?? null;
        $expiresAt = now()->addSeconds($tokenData['expires_in']);

        $email = $this->getEmailFromToken($token);

        $connection = GoogleOAuthConnection::updateOrCreate([
            'user_id' => auth()->id(),
            'service' => $service->value,
            'email' => $email,
        ], [
            'access_token' => $token,
            'refresh_token' => $refreshToken,
            'expires_at' => $expiresAt,
        ]);

        return $connection;
    }

    public function getAccessToken(GoogleOAuthConnection $connection): string
    {
        $cacheKey = "google_oauth_token_{$connection->id}";

        return Cache::remember($cacheKey, self::TOKEN_CACHE_TTL, function () use ($connection) {
            if ($connection->isExpired()) {
                $this->refreshToken($connection);
            }
            return $connection->access_token;
        });
    }

    public function refreshToken(GoogleOAuthConnection $connection): void
    {
        if (!$connection->refresh_token) {
            throw new \RuntimeException('Impossibile rinnovare: nessun refresh token');
        }

        $client = $this->buildClient();
        $client->fetchAccessTokenWithRefreshToken($connection->refresh_token);

        $tokenData = $client->getAccessToken();

        if (isset($tokenData['error'])) {
            $connection->delete();
            Cache::forget("google_oauth_token_{$connection->id}");

            throw new \RuntimeException(
                'Refresh token scaduto o revocato per ' . $connection->email
            );
        }

        $connection->access_token = $tokenData['access_token'];
        $connection->expires_at = now()->addSeconds($tokenData['expires_in']);

        if (isset($tokenData['refresh_token'])) {
            $connection->refresh_token = $tokenData['refresh_token'];
        }

        $connection->save();
        Cache::forget("google_oauth_token_{$connection->id}");
    }

    public function revoke(GoogleOAuthConnection $connection): void
    {
        $client = $this->buildClient();
        $client->revokeToken($connection->access_token);

        $connection->delete();
        Cache::forget("google_oauth_token_{$connection->id}");
    }

    public function createXoAuth2SmtpTransport(
        string $email,
        string $accessToken
    ): \Symfony\Component\Mailer\Transport\Smtp\EsmtpTransport {
        $transport = new \Symfony\Component\Mailer\Transport\Smtp\EsmtpTransport(
            'smtp.gmail.com',
            587,
            true,
        );

        $transport->setUsername($email);
        $transport->setPassword($accessToken);
        $transport->setAuthenticators([
            new \Symfony\Component\Mailer\Transport\Smtp\Auth\XOAuth2Authenticator(),
        ]);

        return $transport;
    }

    private function getEmailFromToken(string $accessToken): string
    {
        $client = $this->buildClient();
        $payload = $client->verifyIdToken($accessToken);

        if ($payload && isset($payload['email'])) {
            return $payload['email'];
        }

        $http = new \GuzzleHttp\Client();
        $response = $http->get('https://www.googleapis.com/oauth2/v1/userinfo?alt=json', [
            'headers' => ['Authorization' => "Bearer $accessToken"],
        ]);
        $data = json_decode((string) $response->getBody(), true);

        return $data['email'];
    }

    public function getConnectionStatus(): array
    {
        $connections = GoogleOAuthConnection::where('user_id', auth()->id())->get();
        $status = [];

        foreach (GoogleService::cases() as $service) {
            $connection = $connections->firstWhere('service', $service->value);
            $status[$service->value] = [
                'connected' => $connection !== null,
                'connection' => $connection,
                'email' => $connection?->email,
                'expired' => $connection?->isExpired() ?? false,
            ];
        }

        return $status;
    }
}