api.php

<?php
class MagentoClient {
  public $bearer_token = '';
  public $base_url = '';

  public function __construct($token, $base_url) {
    $this->base_url = $base_url;
    $this->bearer_token = $token;
  }

  public function request($endpoint, $method = 'GET', $body = FALSE) {

    // Generated by curl-to-PHP: http://incarnate.github.io/curl-to-php/
    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, $this->base_url . $endpoint);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $method);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $body);

      $headers = array();
    $headers[] = "Authorization: Bearer " . $this->bearer_token;
    if ($body) {
      $headers[] = "Content-Type: application/json";
    }
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

    $result = curl_exec($ch);
    if (curl_errno($ch)) {
      echo 'Error:' . curl_error($ch);
    }
    curl_close ($ch);
    return $result;
  }

  public function getProduct($product_id) {
    return $this->request('/products/' . $product_id . '/', 'GET');
  }

  public function createCart() {
    return $this->request('/guest-carts/', 'POST');
  }

  public function addToCart($cart_id, $product_sku, $quantity = 1) {
    $order = array(
      'cartItem' => array(
        'quote_id' => $cart_id,
        'sku' => $product_sku,
        'qty' => $quantity,
      )
    );
    return $this->request('/guest-carts/' . $cart_id . '/items',
      'POST',
      json_encode($order)
      );
  }

  public function setShipping($cart_id, $shipping) {
    return $this->request('/guest-carts/' . $cart_id . '/shipping-information',
      'POST',
      json_encode($shipping)
    );
  }

  public function placeOrder($cart_id, $payment_method = 'cashondelivery') {
    $payment = array(
      'paymentMethod' => array('method' => $payment_method)
    );

    return $this->request('/guest-carts/' . $cart_id . '/order',
      'PUT',
      json_encode($payment)
    );
  }

  public function getPaymentMethods($cart_id) {
    return $this->request('/guest-carts/' . $cart_id . '/payment-information', 'GET');
  }
  
}