PHP Google Calendar API with Service Accounts

functions.php

<?php
/*
  IMPORTANT!
  If you came here from my WP Plugin (https://github.com/hrsetyono/google-calendar-api), you don't need to require the API Client.

  Aside from that, you need to download the client from https://github.com/google/google-api-php-client/releases
  Put it in this directory, then uncomment the require_once code below.
*/

// require_once 'vendor/autoload.php';

class MyCalendar {
  private $client;
  private $calendar_id = 'your-calendar-id@gmail.com'; // find this in Calendar Settings > Click the calendar in sidebar > Integrate

  function __construct() {
    $this->client = new Google_Client();
    
    /*
      The one you download when creating Service Account. Put it in the same folder as this file
    
      In production, please do not put the file openly like this. Use Environment Variables instead
      If you do that, use getenv() instead of file_exists()
      Example: https://github.com/google/google-api-php-client/blob/master/examples/service-account.php
    */
    $cred = __DIR__ . '/service-creds.json';

    if( file_exists($cred) ) {
      $this->client->setAuthConfig( $cred );
      $this->client->addScope( Google_Service_Calendar::CALENDAR_READONLY );
    } else {
      return false;
    }
  }

  function get() {
    $args = array(
      'orderBy' => 'startTime',
      'singleEvents' => TRUE,
      'timeMax' => date('c', strtotime('+6 day') )
    );

    $service = new Google_Service_Calendar( $this->client );
    $results = $service->events->listEvents( $this->calendar_id, $args );

    // if found
    if( count( $results->getItems() ) >= 1 ) {
      return $results->getItems();
    } else {
      return false;
    }
  }

}


////

$cal = new MyCalendar();
$cal_data = $cal->get();

var_dump( $cal_data );