PHP simple google OAuth in Linux

Steps involved!

1. Create a parent directory php-google-signin
2. Download google-api-php-client  library from Github to parent dir
3. Obtain OAuth 2.0 client credentials from the Google API Console. Save the json file as key.json  in to parent dir
4. Set your redirect URL in google api key console

Create a file index.php

<?php
    require_once __DIR__.'/google-api-php-client-2.1.1/vendor/autoload.php';
    date_default_timezone_set('asia/kolkata');
    session_start();

    // to find localhost and production server https
    if ($_SERVER['SERVER_NAME'] == "localhost") {
        $protocol = "http://";
    }else{
        $protocol = "https://";
    }
    $redirect_uri = $protocol . $_SERVER['HTTP_HOST'] . "/index.php";
    $client = new Google_Client();
    $client->setAuthConfigFile('key.json');
    $client->setRedirectUri($protocol . $_SERVER['HTTP_HOST'] . "/index.php");
    $client->setScopes('email'); // You want to retrieve email and domain name
    

// on logout
    if (isset($_REQUEST['logout'])) {
      unset($_SESSION['id_token_token']);
    }

// once you get code after auth success
    if (isset($_GET['code'])) {
      $token = $client->fetchAccessTokenWithAuthCode($_GET['code']);
      $client->setAccessToken($token);
      $_SESSION['id_token_token'] = $token;
      header('Location: ' . filter_var($redirect_uri, FILTER_SANITIZE_URL));
    }
    if ( !empty($_SESSION['id_token_token']) && isset($_SESSION['id_token_token']['id_token']) ) {
      $client->setAccessToken($_SESSION['id_token_token']);
    } else {
      $authUrl = $client->createAuthUrl();
    }
    // success
    if ($client->getAccessToken()) {
      $token_data = $client->verifyIdToken();

// print all the data related after auth
      print_r($token_data)
    }
?>