MailChimp api v3 - request handler for browser

mailchimp_request_handler.php

<?php
include('./MailChimp.php');
use \DrewM\MailChimp\MailChimp;

function cors() {

    // Allow from any origin
    if (isset($_SERVER['HTTP_ORIGIN'])) {
        // Decide if the origin in $_SERVER['HTTP_ORIGIN'] is one
        // you want to allow, and if so:
        header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
        header('Access-Control-Allow-Credentials: true');
        header('Access-Control-Max-Age: 86400');    // cache for 1 day
    }

    // Access-Control headers are received during OPTIONS requests
    if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {

        if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD']))
            // may also be using PUT, PATCH, HEAD etc
            header("Access-Control-Allow-Methods: GET, POST, OPTIONS");

        if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']))
            header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");

        exit(0);
    }
}

cors();

$method = $_SERVER['REQUEST_METHOD'];
$request = explode('/', trim($_SERVER['PATH_INFO'],'/'));
$input = json_decode(file_get_contents('php://input'),true);

if ($method == 'POST' && isset($input["email"])) {
  $MailChimp = new MailChimp('12312312312313-us1');

  $email = $input["email"];

  $list_id = '1111111';
  $result = $MailChimp->post("lists/$list_id/members", [
    'email_address' => $email,
    'status'        => 'pending',
  ]);

  header('Content-type:application/json;charset=utf-8');

  echo json_encode($result);
} else {
  echo 'server';
}