<?php
 
 namespace Telnyx;
 
 /**
  * Class ApiResource
  *
  * @package Telnyx
  */
 abstract class ApiResource extends TelnyxObject
 {
     use ApiOperations\Request;
 
     /**
      * @return \Telnyx\Util\Set A list of fields that can be their own type of
      * API resource (say a nested card under an account for example), and if
      * that resource is set, it should be transmitted to the API on a create or
      * update. Doing so is not the default behavior because API resources
      * should normally be persisted on their own RESTful endpoints.
      */
     public static function getSavedNestedResources()
     {
         static $savedNestedResources = null;
         if ($savedNestedResources === null) {
             $savedNestedResources = new Util\Set();
         }
         return $savedNestedResources;
     }
 
     /**
      * @var boolean A flag that can be set a behavior that will cause this
      * resource to be encoded and sent up along with an update of its parent
      * resource. This is usually not desirable because resources are updated
      * individually on their own endpoints, but there are certain cases,
      * replacing a customer's source for example, where this is allowed.
      */
     public $saveWithParent = false;
 
     public function __set($k, $v)
     {
         parent::__set($k, $v);
         $v = $this->$k;
         if ((static::getSavedNestedResources()->includes($k)) &&
             ($v instanceof ApiResource)) {
             $v->saveWithParent = true;
         }
         return $v;
     }
 
     /**
      * @return ApiResource The refreshed resource.
      */
     public function refresh()
     {
         $requestor = new ApiRequestor($this->_opts->apiKey, static::baseUrl());
         $url = $this->instanceUrl();
 
         list($response, $this->_opts->apiKey) = $requestor->request(
             'get',
             $url,
             $this->_retrieveOptions,
             $this->_opts->headers
         );
         $this->setLastResponse($response);
         $this->refreshFrom($response->json, $this->_opts);
         return $this;
     }
 
     /**
      * @return string The base URL for the given class.
      */
     public static function baseUrl()
     {
         return Telnyx::$apiBase;
     }
 
     /**
      * @return string The endpoint URL for the given class.
      */
     public static function classUrl()
     {
         // Replace dots with slashes for namespaced resources, e.g. if the object's name is
         // "foo.bar", then its URL will be "/v2/foo/bars".
         $base = str_replace('.', '/', static::OBJECT_NAME);
         return "/v2/${base}s";
     }
 
     /**
      * @return string The instance endpoint URL for the given class.
      */
     public static function resourceUrl($id)
     {
         if ($id === null) {
             $class = get_called_class();
             $message = "Could not determine which URL to request: "
                . "$class instance has invalid ID: $id";
             throw new Error\InvalidRequest($message, null);
         }
         $id = Util\Util::utf8($id);
         $base = static::classUrl();
         $extn = urlencode($id);
         return "$base/$extn";
     }
 
     /**
      * @return string The full API URL for this API resource.
      */
     public function instanceUrl()
     {
         return static::resourceUrl($this['id']);
     }
 }