Provider.php

<?php

namespace SocialiteProviders\YouTube;

use GuzzleHttp\RequestOptions;
use SocialiteProviders\Manager\OAuth2\AbstractProvider;
use SocialiteProviders\Manager\OAuth2\User;

class Provider extends AbstractProvider
{
    public const IDENTIFIER = 'YOUTUBE';

    protected $scopes = [
        'https://www.googleapis.com/auth/youtube.readonly',
    ];

    protected $scopeSeparator = ' ';

    protected function getAuthUrl($state): string
    {
        return $this->buildAuthUrlFromBase('https://accounts.google.com/o/oauth2/v2/auth', $state);
    }

    protected function getTokenUrl(): string
    {
        return 'https://oauth2.googleapis.com/token';
    }

    /**
     * {@inheritdoc}
     */
    protected function getUserByToken($token)
    {
        $response = $this->getHttpClient()->get('https://www.googleapis.com/youtube/v3/channels', [
            RequestOptions::HEADERS => [
                'Authorization' => 'Bearer '.$token,
            ],
            RequestOptions::QUERY => [
                'part' => 'snippet',
                'mine' => 'true',
            ],
        ]);

        $responseJson = json_decode((string) $response->getBody(), true);

        return $responseJson['items'][0] ?? [];
    }

    /**
     * {@inheritdoc}
     */
    protected function mapUserToObject(array $user)
    {
        return (new User)->setRaw($user)->map([
            'id'        => $user['id'] ?? null,
            'nickname'  => $user['snippet']['title'] ?? null,
            'name'      => null,
            'email'     => null,
            'avatar'    => $user['snippet']['thumbnails']['high']['url'] ?? null,
        ]);
    }
}