FoxyCart REST API Guzzle Wrapper

<?php
class FoxyCartApiClient
{

    //App Specific
    private $app = "";
    private $config = "";
    public $access_token = "";

    //Vars
    public $last_status_code = "";

    //FoxyCart API Endpoints
    public $api_home_page = "https://api.foxycart.com";
    //public $api_home_page = "https://api-sandbox.foxycart.com";

    //Link Vars
    public $links = array();
    public $rel_base = "https://api.foxycart.com/rels/";
    public $registered_link_relations = array('self', 'first', 'prev', 'next', 'last');

    //Required Headers
    private $required_headers = array(
        'FOXYCART-API-VERSION' => 1,
    );


    public function __construct($app, $access_token = "") {

        //So we can use these later
        $this->app = $app;

        //Set Access Token
        if ($access_token) {
            $this->access_token = $access_token;
        }

    }


    public function get($uri = "", $post = null) {
        return $this->go("GET", $uri, $post);
    }

    public function post($uri, $post = null) {
        return $this->go("POST", $uri, $post);
    }

    public function patch($uri, $post = null) {
        return $this->go("PATCH", $uri, $post);
    }

    public function delete($uri, $post = null) {
        return $this->go("DELETE", $uri, $post);
    }

    public function go($method, $uri, $post) {
        if (!is_array($post)) $post = null;
        if (!$uri) $uri = $this->api_home_page;
        $headers = $this->getHeaders();

        //PATCH Override
        if ($method == "PATCH") {
            $headers['X-HTTP-Method-Override'] = "PATCH";
            $method = "POST";
        }

        //GET Override
        if ($method == "GET" && $post != null) {
            if (strpos($uri, "?") === false) {
                $uri .= "?" . http_build_query($post);
            } else {
                $uri .= "&" . http_build_query($post);
            }
            $post = null;
        }

        //Send Request
        $api_request = $this->app['guzzle']->createRequest($method, $uri, $headers, $post)->send();
        $data = $api_request->json();
        $this->last_status_code = $api_request->getStatusCode();
        $this->saveLinks($data);
        return $data;
    }


    public function saveLinks($data) {
        if (!isset($data['_links'])) return;
        foreach ($data['_links'] as $key => $val) {
            $this->links[$key] = $val;
        }
    }
    public function getLink($str) {
        $search_string = in_array($str, $this->registered_link_relations) ? $str : $this->rel_base . $str;
        if (isset($this->links[$search_string])) {
            return $this->links[$search_string]['href'];
        } else {
            return "";
        }
    }

    public function checkForErrors($data) {
        if ($this->last_status_code != 200) {
            if (is_array($data) && isset($data['error_description'])) {
                return array($data['error_description']);
            } elseif (is_array($data) && isset($data[0]['message'])) {
                return array($data[0]['message']);
            } else {
                return array("No data returned.");
            }
        }
        return false;
    }

    public function getHeaders() {
        $headers = array_merge($this->required_headers, array(
            'Accept' => 'application/hal+json',
            'Content-Type' => 'application/json',
        ));
        if ($this->access_token) {
            $headers['Authorization'] = "Bearer " . $this->access_token;
        }
        return $headers;
    }

    //Set Fields on Init
    public function setApiHomepage($val) {
        $this->api_home_page = $val;
    }

}