Merged FAD-3148 into 2.x

* FAD-3148 basic non-functioning base class

* FAD-3148 a bit more functionality in the base class

* FAD-3148 added custom promise class and custom response class. Did good things to SparkPost class

* Updated Transmission.php for new refactor, still WIP. Created Resource.php as a parent class for all future resources.

* Removed test functions

* Cleaned up Transmissions.php according to PSR-2, deleted more test code and comments.

* added sync and aysnc, cleaned up code

* added support for async/sync option

* added support for async/sync option

* Added interns to authors

* simplified the request function

* added comments

* added user agent

* added comments in SparkPostPromise

* added comments in SparkPostException

* added comments in SparkPostResponse

* cleaning up test

* updated composer.json and contributing files for testing

* Ran php-cs-fixer

* testing for sparkpost response class

* updated to newer version of guzzle

* updated to newer version of guzzle

* Cleaned up getUrl and other functions

* cleaned up constructor and overrode getCode with getResponse()->getStatusCode()

* fixed up then method

* cleaned up getBody

* deleted old test

* Wrote total coverage tests for SparkPost class

* commented out setting up transmissions endpoint until merging with FAD-3146

10 files changed, 378 insertions, 888 deletions

diff --git a/lib/SendGridCompatibility/Email.php b/lib/SendGridCompatibility/Email.php
deleted file mode 100644
index 3ca2466..0000000
--- a/lib/SendGridCompatibility/Email.php
+++ /dev/null
@@ -1,259 +0,0 @@
-<?php
-
-namespace SparkPost\SendGridCompatibility;
-
-class Email
-{
-    public $model;
-
-    /**
-     * Sets up the model for saving the configuration.
-     */
-    public function __construct()
-    {
-        $this->model = array();
-    }
-
-    /**
-     * adds addresses as recipients.
-     *
-     * @param string $address
-     * @param string $name    optional
-     *
-     * @return $this
-     */
-    public function addTo($address, $name = null)
-    {
-        if (!isset($this->model['recipients'])) {
-            $this->model['recipients'] = array();
-        }
-
-        if (isset($name)) {
-            $address = array('address' => array('email' => $address, 'name' => $name));
-        } else {
-            $address = array('address' => array('email' => $address));
-        }
-
-        array_push($this->model['recipients'], $address);
-
-        return $this;
-    }
-
-    /**
-     * explicitly sets a list of addresses.
-     *
-     * @param array $addresses
-     *
-     * @return $this
-     */
-    public function setTos(array $addresses)
-    {
-        $this->model['recipients'] = $addresses;
-
-        return $this;
-    }
-
-    /**
-     * sets the from address.
-     *
-     * @param string $address
-     *
-     * @return $this
-     */
-    public function setFrom($address)
-    {
-        $this->model['from'] = array('email' => $address);
-
-        return $this;
-    }
-
-    /**
-     * Sets the name for the from address.
-     *
-     * @param string $name
-     *
-     * @return $this
-     *
-     * @throws \Exception
-     */
-    public function setFromName($name)
-    {
-        if (!isset($this->model['from'])) {
-            throw new \Exception('Must set \'From\' prior to setting \'From Name\'.');
-        }
-        $this->model['from']['name'] = $name;
-
-        return $this;
-    }
-
-    /**
-     * sets the reply to field.
-     *
-     * @param string $address
-     *
-     * @return $this
-     */
-    public function setReplyTo($address)
-    {
-        $this->model['replyTo'] = $address;
-
-        return $this;
-    }
-
-    /**
-     * throws an error because bcc fields are not yet implemented.
-     *
-     * @throws \Exception
-     *
-     * @param string $address
-     *
-     * @return $this
-     */
-    public function addBcc($address)
-    {
-        throw new \Exception('Adding bcc recipients is not yet supported, try adding them as a \'to\' address');
-    }
-
-    /**
-     * sets the subject header.
-     *
-     * @param string $subject
-     *
-     * @return $this
-     */
-    public function setSubject($subject)
-    {
-        $this->model['subject'] = $subject;
-
-        return $this;
-    }
-
-    /**
-     * sets the text body.
-     *
-     * @param string $text
-     *
-     * @return $this
-     */
-    public function setText($text)
-    {
-        $this->model['text'] = $text;
-
-        return $this;
-    }
-
-    /**
-     * sets the html body.
-     *
-     * @param string $html
-     *
-     * @return $this
-     */
-    public function setHtml($html)
-    {
-        $this->model['html'] = $html;
-
-        return $this;
-    }
-
-    /**
-     * Throws an exception since adding categories is not yet supported.
-     *
-     * @param string $category
-     *
-     * @throws \Exception
-     */
-    public function addCategory($category)
-    {
-        throw new \Exception('Adding categories is not yet supported');
-    }
-
-    /**
-     * Throws an exception since adding attachments is not yet supported.
-     *
-     * @throws \Exception
-     *
-     * @param mixed $attachment
-     */
-    public function addAttachment($attachment)
-    {
-        throw new \Exception('Adding attachments is not yet supported');
-    }
-
-    /**
-     * Adds transmission level substitution data.
-     *
-     * @param string $name
-     * @param mixed  $values
-     *
-     * @return $this
-     */
-    public function addSubstitution($name, $values)
-    {
-        if (!isset($this->model['substitutionData'])) {
-            $this->model['substitutionData'] = array();
-        }
-        $this->model['substitutionData'][$name] = $values;
-
-        return $this;
-    }
-
-    /**
-     * Adds transmission level substitution data.
-     *
-     * @param string $name
-     * @param mixed  $values
-     */
-    public function addSection($name, $values)
-    {
-        $this->addSubstitution($name, $values);
-    }
-
-    /**
-     * Throws an exception because arguments for third party systems is not supported.
-     *
-     * @throws \Exception
-     *
-     * @param mixed $value
-     */
-    public function addUniqueArg($key, $value)
-    {
-        throw new \Exception('Adding Unique Arguments is not yet supported');
-    }
-
-    /**
-     * Throws an exception because arguments for third party systems is not supported.
-     *
-     * @throws \Exception
-     *
-     * @param mixed $values
-     */
-    public function setUniqueArgs(array $values)
-    {
-        throw new \Exception('Setting Unique Arguments is not yet supported');
-    }
-
-    /**
-     * Adds custom headers to the email header.
-     *
-     * @param string $name
-     * @param string $value
-     */
-    public function addHeader($name, $value)
-    {
-        if (!isset($this->model['customHeaders'])) {
-            $this->model['customHeaders'] = array();
-        }
-        $this->model['customHeaders'][$name] = $value;
-    }
-
-    /**
-     * converts this object to a configuration for a SparkPost transmission.
-     *
-     * @return array
-     */
-    public function toSparkPostTransmission()
-    {
-        return $this->model;
-    }
-}
diff --git a/lib/SendGridCompatibility/SendGrid.php b/lib/SendGridCompatibility/SendGrid.php
deleted file mode 100644
index c5e84c1..0000000
--- a/lib/SendGridCompatibility/SendGrid.php
+++ /dev/null
@@ -1,26 +0,0 @@
-<?php
-
-namespace SparkPost\SendGridCompatibility;
-
-use SparkPost\SparkPost;
-
-class SendGrid
-{
-    private $sparky;
-
-    public function __construct($username, $password, $options = null, $httpAdapter)
-    {
-        //username isn't used in our system
-        $opts = array('key' => $password);
-        if (!is_null($options)) {
-            $opts = array_merge($opts, $options);
-        }
-
-        $this->sparky = new SparkPost($httpAdapter, $opts);
-    }
-
-    public function send(Email $email)
-    {
-        $this->sparky->transmission->send($email->toSparkPostTransmission());
-    }
-}
diff --git a/lib/SparkPost/APIResource.php b/lib/SparkPost/APIResource.php
deleted file mode 100644
index 36b03a8..0000000
--- a/lib/SparkPost/APIResource.php
+++ /dev/null
@@ -1,265 +0,0 @@
-<?php
-
-namespace SparkPost;
-
-/**
- * SDK interface for managing SparkPost API endpoints.
- */
-class APIResource
-{
-    /**
-     * name of the API endpoint, mainly used for URL construction.
-     * This is public to provide an interface.
-     *
-     * @var string
-     */
-    public $endpoint;
-
-    /**
-     * Mapping for values passed into the send method to the values needed for the respective API.
-     *
-     * @var array
-     */
-    protected static $parameterMappings = [];
-
-    /**
-     * Sets up default structure and default values for the model that is acceptable by the API.
-     *
-     * @var array
-     */
-    protected static $structure = [];
-
-    /**
-     * SparkPost reference for httpAdapters and configs.
-     */
-    protected $sparkpost;
-
-    /**
-     * Initializes config and httpAdapter for use later.
-     *
-     * @param $sparkpost \SparkPost\SparkPost provides api configuration information
-     */
-    public function __construct(SparkPost $sparkpost)
-    {
-        $this->sparkpost = $sparkpost;
-    }
-
-    /**
-     * Private Method helper to reference parameter mappings and set the right value for the right parameter.
-     *
-     * @param array  $model  (pass by reference) the set of values to map
-     * @param string $mapKey a dot syntax path determining which value to set
-     * @param mixed  $value  value for the given path
-     */
-    protected function setMappedValue(&$model, $mapKey, $value)
-    {
-        //get mapping
-        if (empty(static::$parameterMappings)) {
-            // if parameterMappings is empty we can assume that no wrapper is defined
-            // for the current endpoint and we will use the mapKey to define the mappings directly
-            $mapPath = $mapKey;
-        } elseif (array_key_exists($mapKey, static::$parameterMappings)) {
-            // use only defined parameter mappings to construct $model
-            $mapPath = static::$parameterMappings[$mapKey];
-        } else {
-            return;
-        }
-
-        $path = explode('.', $mapPath);
-        $temp = &$model;
-        foreach ($path as $key) {
-            if (!isset($temp[$key])) {
-                $temp[$key] = null;
-            }
-            $temp = &$temp[$key];
-        }
-        $temp = $value;
-    }
-
-    /**
-     * maps values from the passed in model to those needed for the request.
-     *
-     * @param array $requestConfig the passed in model
-     * @param array $model         the set of defaults
-     *
-     * @return array A model ready for the body of a request
-     */
-    protected function buildRequestModel(array $requestConfig, array $model = [])
-    {
-        foreach ($requestConfig as $key => $value) {
-            $this->setMappedValue($model, $key, $value);
-        }
-
-        return $model;
-    }
-
-    /**
-     * posts to the api with a supplied body.
-     *
-     * @param array $body post body for the request
-     *
-     * @return array Result of the request
-     */
-    public function create(array $body = [])
-    {
-        return $this->callResource('post', null, ['body' => $body]);
-    }
-
-    /**
-     * Makes a put request to the api with a supplied body.
-     *
-     * @param $resourcePath
-     * @param array $body Put body for the request
-     *
-     * @return array Result of the request
-     *
-     * @throws APIResponseException
-     */
-    public function update($resourcePath, array $body = [])
-    {
-        return $this->callResource('put', $resourcePath, ['body' => $body]);
-    }
-
-    /**
-     * Wrapper method for issuing GET request to current API endpoint.
-     *
-     * @param string $resourcePath (optional) string resource path of specific resource
-     * @param array  $query        (optional) query string parameters
-     *
-     * @return array Result of the request
-     */
-    public function get($resourcePath = null, array $query = [])
-    {
-        return $this->callResource('get', $resourcePath, ['query' => $query]);
-    }
-
-    /**
-     * Wrapper method for issuing DELETE request to current API endpoint.
-     *
-     * @param string $resourcePath (optional) string resource path of specific resource
-     * @param array  $query        (optional) query string parameters
-     *
-     * @return array Result of the request
-     */
-    public function delete($resourcePath = null, array $query = [])
-    {
-        return $this->callResource('delete', $resourcePath, ['query' => $query]);
-    }
-
-    /**
-     * assembles a URL for a request.
-     *
-     * @param string $resourcePath path after the initial endpoint
-     * @param array  $options      array with an optional value of query with values to build a querystring from.  Any
-     *                             query elements that are themselves arrays will be imploded into a comma separated list.
-     *
-     * @return string the assembled URL
-     */
-    private function buildUrl($resourcePath, $options)
-    {
-        $url = "/{$this->endpoint}/";
-        if (!is_null($resourcePath)) {
-            $url .= $resourcePath;
-        }
-
-        if (!empty($options['query'])) {
-            // check each query element - if it's an array, implode it to match the API-accepted format
-            foreach ($options['query'] as &$element) {
-                if (is_array($element)) {
-                    $element = implode(',', $element);
-                }
-            }
-
-            $queryString = http_build_query($options['query']);
-            $url .= '?'.$queryString;
-        }
-
-        return $url;
-    }
-
-    /**
-     * Prepares a body for put and post requests.
-     *
-     * @param array $options array with an optional value of body with values to build a request body from.
-     *
-     * @return string|null A json encoded string or null if no body was provided
-     */
-    private function buildBody($options)
-    {
-        $body = null;
-        if (!empty($options['body'])) {
-            $model = static::$structure;
-            $requestModel = $this->buildRequestModel($options['body'], $model);
-            $body = json_encode($requestModel);
-        }
-
-        return $body;
-    }
-
-    /**
-     * Private Method for issuing GET and DELETE request to current API endpoint.
-     *
-     *  This method is responsible for getting the collection _and_
-     *  a specific entity from the API endpoint
-     *
-     *  If resourcePath parameter is omitted, then we fetch the collection
-     *
-     * @param string $action       HTTP method type
-     * @param string $resourcePath (optional) string resource path of specific resource
-     * @param array  $options      (optional) query string parameters
-     *
-     * @return array Result set of action performed on resource
-     *
-     * @throws APIResponseException
-     */
-    private function callResource($action, $resourcePath = null, $options = [])
-    {
-        $action = strtoupper($action); // normalize
-
-        $url = $this->buildUrl($resourcePath, $options);
-        $body = $this->buildBody($options);
-
-        //make request
-        try {
-            $response = $this->sparkpost->httpAdapter->send($url, $action, $this->sparkpost->getHttpHeaders(), $body);
-
-            $statusCode = $response->getStatusCode();
-
-            // Handle 4XX responses, 5XX responses will throw an HttpAdapterException
-            if ($statusCode < 400) {
-                return json_decode($response->getBody()->getContents(), true);
-            } elseif ($statusCode === 403) {
-                $response = json_decode($response->getBody(), true);
-                throw new APIResponseException(
-                    'Request forbidden',
-                    $statusCode,
-                    isset($response['errors'][0]['message']) ? $response['errors'][0]['message'] : 'Request forbidden',
-                    isset($response['errors'][0]['code']) ? $response['errors'][0]['code'] : 1100,
-                    isset($response['errors'][0]['description']) ? $response['errors'][0]['description'] : 'Does this API Key have the correct permissions?'
-                );
-            } elseif ($statusCode === 404) {
-                throw new APIResponseException('The specified resource does not exist', 404);
-            } else {
-                $response = json_decode($response->getBody(), true);
-                throw new APIResponseException(
-                    'Received bad response from '.ucfirst($this->endpoint),
-                    $statusCode,
-                    isset($response['errors'][0]['message']) ? $response['errors'][0]['message'] : '',
-                    isset($response['errors'][0]['code']) ? $response['errors'][0]['code'] : 0,
-                    isset($response['errors'][0]['description']) ? $response['errors'][0]['description'] : ''
-                );
-            }
-        }
-
-        /*
-         * Configuration Errors, and a catch all for other errors
-         */
-        catch (\Exception $exception) {
-            if ($exception instanceof APIResponseException) {
-                throw $exception;
-            }
-
-            throw new APIResponseException('Unable to contact '.ucfirst($this->endpoint).' API: '.$exception->getMessage(), $exception->getCode());
-        }
-    }
-}
diff --git a/lib/SparkPost/APIResponseException.php b/lib/SparkPost/APIResponseException.php
deleted file mode 100644
index a491b3c..0000000
--- a/lib/SparkPost/APIResponseException.php
+++ /dev/null
@@ -1,62 +0,0 @@
-<?php
-
-namespace SparkPost;
-
-class APIResponseException extends \Exception
-{
-    /**
-     * @var string
-     */
-    protected $apiMessage;
-
-    /**
-     * @var int
-     */
-    protected $apiCode;
-
-    /**
-     * @var string
-     */
-    protected $apiDescription;
-
-    /**
-     * Construct the exception.
-     */
-    public function __construct($message = '', $code = 0, $apiMessage = '', $apiCode = 0, $apiDescription = '')
-    {
-        $this->apiMessage = $apiMessage;
-        $this->apiCode = $apiCode;
-        $this->apiDescription = $apiDescription;
-        parent::__construct($message, $code);
-    }
-
-    /**
-     * Gets the Exception message.
-     *
-     * @return string the Exception message as a string.
-     */
-    public function getAPIMessage()
-    {
-        return $this->apiMessage;
-    }
-
-    /**
-     * Gets the API Exception code.
-     *
-     * @return int the exception code as integer.
-     */
-    public function getAPICode()
-    {
-        return $this->apiCode;
-    }
-
-    /**
-     * Gets the Exception description.
-     *
-     * @return string the Exception description as a string.
-     */
-    public function getAPIDescription()
-    {
-        return $this->apiDescription;
-    }
-}
diff --git a/lib/SparkPost/MessageEvents.php b/lib/SparkPost/MessageEvents.php
deleted file mode 100644
index d44a30f..0000000
--- a/lib/SparkPost/MessageEvents.php
+++ /dev/null
@@ -1,64 +0,0 @@
-<?php
-
-namespace SparkPost;
-
-/**
- * SDK class for querying the Message Events API.
- *
- * @see https://developers.sparkpost.com/api/#/reference/message-events
- */
-class MessageEvents extends APIResource
-{
-    /**
-     * @var string
-     */
-    public $endpoint = 'message-events';
-
-    /**
-     * Method for issuing search requests to the Message Events API.
-     *
-     * The method passes-through all of the query parameters - the valid ones are listed at
-     *
-     * @link https://developers.sparkpost.com/api/#/reference/message-events/events-documentation/search-for-message-events
-     *
-     * @param array $queryParams The query parameters.  Note that a query parameter containing an array
-     *                           is collapsed into a comma-separated list.
-     *
-     * @return array The result of the query.
-     */
-    public function search(array $queryParams)
-    {
-        // check for DateTime objects & replace them with the formatted string equivalent
-        foreach (['from', 'to'] as $dateTimeParam) {
-            if (isset($queryParams[$dateTimeParam]) && $queryParams[$dateTimeParam] instanceof \DateTime) {
-                // the message events API doesn't allow the seconds or GMT offset, so strip them
-                $queryParams[$dateTimeParam] = substr($queryParams[$dateTimeParam]->format(\DateTime::ATOM), 0, 16);
-            }
-        }
-
-        return $this->get(null, $queryParams);
-    }
-
-    /**
-     * List descriptions of the event fields that could be included in a response from the MessageEvent::search() method.
-     *
-     * @return array The event field descriptions.
-     */
-    public function documentation()
-    {
-        return $this->get('events/documentation');
-    }
-
-    /**
-     * List examples of the event data that will be included in a response from the MessageEvent::search() method.
-     *
-     * @param array $events (optional) Event types for which to get a sample payload.  If not provided, samples
-     *                      for all events will be returned.
-     *
-     * @return array Sample events.
-     */
-    public function samples(array $events = [])
-    {
-        return $this->get('events/samples', ['events' => $events]);
-    }
-}
diff --git a/lib/SparkPost/SparkPost.php b/lib/SparkPost/SparkPost.php
index ff8b456..e76bcd0 100644
--- a/lib/SparkPost/SparkPost.php
+++ b/lib/SparkPost/SparkPost.php
@@ -2,151 +2,238 @@
 
 namespace SparkPost;
 
-use Ivory\HttpAdapter\Configuration;
-use Ivory\HttpAdapter\HttpAdapterInterface;
+use Http\Client\HttpClient;
+use Http\Client\HttpAsyncClient;
+use GuzzleHttp\Psr7\Request as Request;
 
 class SparkPost
 {
-    public $transmission;
-    public $messageEvents;
-
     /**
      * Library version, used for setting User-Agent.
      */
-    private $version = '1.2.1';
+    private $version = '2.0.0';
 
     /**
-     * Connection config for making requests.
+     * HttpClient used to make requests.
      */
-    private $config;
+    public $httpClient;
 
     /**
-     * @var \Ivory\HttpAdapter\HttpAdapterInterface to make requests through.
+     * Options for requests.
      */
-    public $httpAdapter;
+    private $options;
 
     /**
-     * Default config values. Passed in values will override these.
+     * Default options for requests that can be overridden with the setOptions function.
      */
-    private static $apiDefaults = [
+    private static $defaultOptions = [
         'host' => 'api.sparkpost.com',
         'protocol' => 'https',
         'port' => 443,
-        'strictSSL' => true,
         'key' => '',
         'version' => 'v1',
-        'timeout' => 10
+        'timeout' => 10,
+        'async' => true,
     ];
 
     /**
-     * Sets up httpAdapter and config.
-     *
-     * Sets up instances of sub libraries.
+     * Instance of Transmission class.
+     */
+    public $transmissions;
+
+    /**
+     * Sets up the SparkPost instance.
+     * 
+     * @param HttpClient $httpClient - An httplug client or adapter
+     * @param array      $options    - An array to overide default options or a string to be used as an API key
+     */
+    public function __construct(HttpClient $httpClient, $options)
+    {
+        $this->setOptions($options);
+        $this->setHttpClient($httpClient);
+        $this->setupEndpoints();
+    }
+
+    /**
+     * Sends either sync or async request based on async option.
      *
-     * @param \Ivory\HttpAdapter\HttpAdapterInterface $httpAdapter    - An adapter for making http requests
-     * @param string | array                          $settingsConfig - Hashmap that contains config values
-     *                                                                for the SDK to connect to SparkPost. If its a string we assume that
-     *                                                                its just they API Key.
+     * @param string $method
+     * @param string $uri
+     * @param array  $payload - either used as the request body or url query params
+     * @param array  $headers
+     * 
+     * @return SparkPostPromise or SparkPostResponse depending on sync or async request
      */
-    public function __construct($httpAdapter, $settingsConfig)
+    public function request($method = 'GET', $uri = '', $payload = [], $headers = [])
     {
-        //config needs to be setup before adapter because of default adapter settings
-        $this->setConfig($settingsConfig);
-        $this->setHttpAdapter($httpAdapter);
+        if ($this->options['async'] === true) {
+            return $this->asyncRequest($method, $uri, $payload, $headers);
+        } else {
+            return $this->syncRequest($method, $uri, $payload, $headers);
+        }
+    }
 
-        $this->transmission = new Transmission($this);
-        $this->messageEvents = new MessageEvents($this);
+    /**
+     * Sends sync request to SparkPost API.
+     *
+     * @param string $method
+     * @param string $uri
+     * @param array  $payload
+     * @param array  $headers
+     * 
+     * @return SparkPostResponse
+     *
+     * @throws SparkPostException
+     */
+    public function syncRequest($method = 'GET', $uri = '', $payload = [], $headers = [])
+    {
+        $request = $this->buildRequest($method, $uri, $payload, $headers);
+        try {
+            return new SparkPostResponse($this->httpClient->sendRequest($request));
+        } catch (\Exception $exception) {
+            throw new SparkPostException($exception);
+        }
     }
 
     /**
-     * Creates an unwrapped api interface for endpoints that aren't yet supported.
-     * The new resource is attached to this object as well as returned.
+     * Sends async request to SparkPost API.
      *
-     * @param string $endpoint
+     * @param string $method
+     * @param string $uri
+     * @param array  $payload
+     * @param array  $headers
+     * 
+     * @return SparkPostPromise
+     */
+    public function asyncRequest($method = 'GET', $uri = '', $payload = [], $headers = [])
+    {
+        if ($this->httpClient instanceof HttpAsyncClient) {
+            $request = $this->buildRequest($method, $uri, $payload, $headers);
+
+            return new SparkPostPromise($this->httpClient->sendAsyncRequest($request));
+        } else {
+            throw new \Exception('Your http client does not support asynchronous requests. Please use a different client or use synchronous requests.');
+        }
+    }
+
+    /** 
+     * Builds request from given params.
+     *
+     * @param string $method
+     * @param string $uri
+     * @param array  $payload
+     * @param array  $headers
      *
-     * @return APIResource - the unwrapped resource
+     * @return GuzzleHttp\Psr7\Request - A Psr7 compliant request
      */
-    public function setupUnwrapped($endpoint)
+    public function buildRequest($method, $uri, $payload, $headers)
     {
-        $this->{$endpoint} = new APIResource($this);
-        $this->{$endpoint}->endpoint = $endpoint;
+        $method = trim(strtoupper($method));
+
+        if ($method === 'GET') {
+            $params = $payload;
+            $body = [];
+        } else {
+            $params = [];
+            $body = $payload;
+        }
 
-        return $this->{$endpoint};
+        $url = $this->getUrl($uri, $params);
+        $headers = $this->getHttpHeaders($headers);
+
+        return new Request($method, $url, $headers, json_encode($body));
     }
 
     /**
-     * Merges passed in headers with default headers for http requests.
+     * Returns an array for the request headers.
+     *
+     * @param array $headers - any custom headers for the request
+     *
+     * @return array $headers - headers for the request
      */
-    public function getHttpHeaders()
+    public function getHttpHeaders($headers = [])
     {
-        $defaultOptions = [
-            'Authorization' => $this->config['key'],
+        $constantHeaders = [
+            'Authorization' => $this->options['key'],
             'Content-Type' => 'application/json',
+            'User-Agent' => 'php-sparkpost/'.$this->version,
         ];
 
-        return $defaultOptions;
+        foreach ($constantHeaders as $key => $value) {
+            $headers[$key] = $value;
+        }
+
+        return $headers;
     }
 
     /**
-     * Helper function for getting the configuration for http requests.
+     * Builds the request url from the options and given params.
      *
-     * @param array $config
+     * @param string $path   - the path in the url to hit
+     * @param array  $params - query parameters to be encoded into the url
      *
-     * @return Configuration
+     * @return string $url - the url to send the desired request to
      */
-    private function getHttpConfig($config)
+    public function getUrl($path, $params = [])
     {
-        // create Configuration for http adapter
-        $httpConfig = new Configuration();
-        $baseUrl = $config['protocol'].'://'.$config['host'].($config['port'] ? ':'.$config['port'] : '').'/api/'.$config['version'];
-        $httpConfig->setBaseUri($baseUrl);
-        $httpConfig->setTimeout($this->config['timeout']);
-        $httpConfig->setUserAgent('php-sparkpost/'.$this->version);
-
-        return $httpConfig;
+        $options = $this->options;
+
+        $paramsArray = [];
+        foreach ($params as $key => $value) {
+            if (is_array($value)) {
+                $value = implode(',', $value);
+            }
+
+            array_push($paramsArray, $key.'='.$value);
+        }
+
+        $paramsString = implode('&', $paramsArray);
+
+        return $options['protocol'].'://'.$options['host'].($options['port'] ? ':'.$options['port'] : '').'/api/'.$options['version'].'/'.$path.($paramsString ? '?'.$paramsString : '');
     }
 
-    /**
-     * Validates and sets up the httpAdapter.
-     *
-     * @param $httpAdapter \Ivory\HttpAdapter\HttpAdapterInterface to make requests through.
+    /** 
+     * Sets $httpClient to be used for request.
      *
-     * @throws \Exception
+     * @param Http\Client\HttpClient $httpClient - the client to be used for request
      */
-    public function setHttpAdapter(HttpAdapterInterface $httpAdapter)
+    public function setHttpClient(HttpClient $httpClient)
     {
-        $this->httpAdapter = $httpAdapter;
-        $this->httpAdapter->setConfiguration($this->getHttpConfig($this->config));
+        $this->httpClient = $httpClient;
     }
 
     /**
-     * Allows the user to pass in values to override the defaults and set their API key.
-     *
-     * @param string | array $settingsConfig - Hashmap that contains config values
-     *                                       for the SDK to connect to SparkPost. If its a string we assume that
-     *                                       its just they API Key.
+     * Sets the options from the param and defaults for the SparkPost object.
      *
-     * @throws \Exception
+     * @param array $options - either an string API key or an array of options
      */
-    public function setConfig($settingsConfig)
+    public function setOptions($options)
     {
-        // if the config map is a string we should assume that its an api key
-        if (is_string($settingsConfig)) {
-            $settingsConfig = ['key' => $settingsConfig];
+        // if the options map is a string we should assume that its an api key
+        if (is_string($options)) {
+            $options = ['key' => $options];
         }
 
         // Validate API key because its required
-        if (!isset($settingsConfig['key']) || !preg_match('/\S/', $settingsConfig['key'])) {
+        if (!isset($this->options['key']) && (!isset($options['key']) || !preg_match('/\S/', $options['key']))) {
             throw new \Exception('You must provide an API key');
         }
 
-        $this->config = self::$apiDefaults;
+        $this->options = isset($this->options) ? $this->options : self::$defaultOptions;
 
-        // set config, overriding defaults
-        foreach ($settingsConfig as $configOption => $configValue) {
-            if (key_exists($configOption, $this->config)) {
-                $this->config[$configOption] = $configValue;
+        // set options, overriding defaults
+        foreach ($options as $option => $value) {
+            if (key_exists($option, $this->options)) {
+                $this->options[$option] = $value;
             }
         }
     }
+
+    /**
+     * Sets up any endpoints from custom classes e.g. $this->transmissions.
+     */
+    private function setupEndpoints()
+    {
+        // $this->transmissions = new Transmission($this);
+    }
 }
diff --git a/lib/SparkPost/SparkPostException.php b/lib/SparkPost/SparkPostException.php
new file mode 100644
index 0000000..ca92e24
--- /dev/null
+++ b/lib/SparkPost/SparkPostException.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace SparkPost;
+
+use Http\Client\Exception\HttpException as HttpException;
+
+class SparkPostException extends \Exception
+{
+    /**
+     * Variable to hold json decoded body from http response.
+     */
+    private $body = null;
+
+    /**
+     * Sets up the custom exception and copies over original exception values.
+     *
+     * @param Exception $exception - the exception to be wrapped
+     */
+    public function __construct(\Exception $exception)
+    {
+        $message = $exception->getMessage();
+        $code = $exception->getCode();
+        if ($exception instanceof HttpException) {
+            $message = $exception->getResponse()->getBody()->__toString();
+            $this->body = json_decode($message, true);
+            $code = $exception->getResponse()->getStatusCode();
+        }
+
+        parent::__construct($message, $code, $exception->getPrevious());
+    }
+
+    /**
+     * Returns the body.
+     *
+     * @return array $body - the json decoded body from the http response
+     */
+    public function getBody()
+    {
+        return $this->body;
+    }
+}
diff --git a/lib/SparkPost/SparkPostPromise.php b/lib/SparkPost/SparkPostPromise.php
new file mode 100644
index 0000000..15f129f
--- /dev/null
+++ b/lib/SparkPost/SparkPostPromise.php
@@ -0,0 +1,69 @@
+<?php
+
+namespace SparkPost;
+
+use Http\Promise\Promise as HttpPromise;
+
+class SparkPostPromise implements HttpPromise
+{
+    /**
+     * HttpPromise to be wrapped by SparkPostPromise.
+     */
+    private $promise;
+
+    /**
+     * set the promise to be wrapped.
+     *
+     * @param HttpPromise $promise
+     */
+    public function __construct(HttpPromise $promise)
+    {
+        $this->promise = $promise;
+    }
+
+    /**
+     * Hand off the response functions to the original promise and return a custom response or exception.
+     *
+     * @param callable $onFulfilled - function to be called if the promise is fulfilled
+     * @param callable $onRejected  - function to be called if the promise is rejected
+     */
+    public function then(callable $onFulfilled = null, callable $onRejected = null)
+    {
+        return $this->promise->then(function($response) use ($onFulfilled) {
+            if (isset($onFulfilled))
+                $onFulfilled(new SparkPostResponse($response));
+        }, function($exception) use ($onRejected) {
+            if (isset($onRejected))
+                $onRejected(new SparkPostException($exception));
+        });
+    }
+
+    /**
+     * Hand back the state.
+     *
+     * @return $state - returns the state of the promise
+     */
+    public function getState()
+    {
+        return $this->promise->getState();
+    }
+
+    /**
+     * Wraps the wait function and returns a custom response or throws a custom exception.
+     *
+     * @param bool $unwrap
+     *
+     * @return SparkPostResponse
+     *
+     * @throws SparkPostException
+     */
+    public function wait($unwrap = true)
+    {
+        try {
+            $response = $this->promise->wait($unwrap);
+            return $response ? new SparkPostResponse($response) : $response;
+        } catch (\Exception $exception) {
+            throw new SparkPostException($exception);
+        }
+    }
+}
diff --git a/lib/SparkPost/SparkPostResponse.php b/lib/SparkPost/SparkPostResponse.php
new file mode 100644
index 0000000..9104b33
--- /dev/null
+++ b/lib/SparkPost/SparkPostResponse.php
@@ -0,0 +1,105 @@
+<?php
+
+namespace SparkPost;
+
+use Psr\Http\Message\ResponseInterface as ResponseInterface;
+use Psr\Http\Message\StreamInterface as StreamInterface;
+
+class SparkPostResponse implements ResponseInterface
+{
+    /**
+     * ResponseInterface to be wrapped by SparkPostResponse.
+     */
+    private $response;
+
+    /**
+     * set the response to be wrapped.
+     *
+     * @param ResponseInterface $response
+     */
+    public function __construct(ResponseInterface $response)
+    {
+        $this->response = $response;
+    }
+
+    /**
+     * Returns the body.
+     *
+     * @return array $body - the json decoded body from the http response
+     */
+    public function getBody()
+    {
+        $body = $this->response->getBody();
+        $body_string = $body->__toString();
+
+        $json = json_decode($body_string, true);
+
+        return $json;    
+    }
+
+    // pass these down to the response given in the constructor
+    public function getProtocolVersion()
+    {
+        return $this->response->getProtocolVersion();
+    }
+
+    public function withProtocolVersion($version)
+    {
+        return $this->response->withProtocolVersion($version);
+    }
+
+    public function getHeaders()
+    {
+        return $this->response->getHeaders();
+    }
+
+    public function hasHeader($name)
+    {
+        return $this->response->hasHeader($name);
+    }
+
+    public function getHeader($name)
+    {
+        return $this->response->getHeader($name);
+    }
+
+    public function getHeaderLine($name)
+    {
+        return $this->response->getHeaderLine($name);
+    }
+
+    public function withHeader($name, $value)
+    {
+        return $this->response->withHeader($name, $value);
+    }
+
+    public function withAddedHeader($name, $value)
+    {
+        return $this->response->withAddedHeader($name, $value);
+    }
+
+    public function withoutHeader($name)
+    {
+        return $this->response->withoutHeader($name);
+    }
+
+    public function withBody(StreamInterface $body)
+    {
+        return $this->response->withBody($body);
+    }
+
+    public function getStatusCode()
+    {
+        return $this->response->getStatusCode();
+    }
+
+    public function withStatus($code, $reasonPhrase = '')
+    {
+        return $this->response->withStatus($code, $reasonPhrase);
+    }
+
+    public function getReasonPhrase()
+    {
+        return $this->response->getReasonPhrase();
+    }
+}
diff --git a/lib/SparkPost/Transmission.php b/lib/SparkPost/Transmission.php
deleted file mode 100644
index ff63722..0000000
--- a/lib/SparkPost/Transmission.php
+++ /dev/null
@@ -1,136 +0,0 @@
-<?php
-
-namespace SparkPost;
-
-/**
- * SDK interface for managing transmissions.
- */
-class Transmission extends APIResource
-{
-    public $endpoint = 'transmissions';
-
-    /**
-     * Mapping for values passed into the send method to the values needed for the Transmission API.
-     *
-     * @var array
-     */
-    protected static $parameterMappings = [
-        'attachments' => 'content.attachments',
-        'campaign' => 'campaign_id',
-        'customHeaders' => 'content.headers',
-        'description' => 'description',
-        'from' => 'content.from',
-        'html' => 'content.html',
-        'inlineCss' => 'options.inline_css',
-        'inlineImages' => 'content.inline_images',
-        'metadata' => 'metadata',
-        'recipientList' => 'recipients.list_id',
-        'recipients' => 'recipients',
-        'replyTo' => 'content.reply_to',
-        'returnPath' => 'return_path',
-        'rfc822' => 'content.email_rfc822',
-        'sandbox' => 'options.sandbox',
-        'startTime' => 'options.start_time',
-        'subject' => 'content.subject',
-        'substitutionData' => 'substitution_data',
-        'template' => 'content.template_id',
-        'text' => 'content.text',
-        'trackClicks' => 'options.click_tracking',
-        'trackOpens' => 'options.open_tracking',
-        'transactional' => 'options.transactional',
-        'useDraftTemplate' => 'use_draft_template',
-    ];
-
-    /**
-     * Sets up default structure and default values for the model that is acceptable by the API.
-     *
-     * @var array
-     */
-    protected static $structure = [
-        'return_path' => 'default@sparkpostmail.com',
-        'content' => [
-            'html' => null,
-            'text' => null,
-            'email_rfc822' => null,
-        ],
-        'use_draft_template' => false,
-    ];
-
-    /**
-     * Method for issuing POST request to the Transmissions API.
-     *
-     *  This method assumes that all the appropriate fields have
-     *  been populated by the user through configuration.  Acceptable
-     *  configuration values are:
-     *  'attachments': array,
-     *  'campaign': string,
-     *  'customHeaders': array,
-     *  'description': string,
-     *  'from': string,
-     *  'html': string,
-     *  'inlineCss': boolean,
-     *  'inlineImages': array,
-     *  'metadata': array,
-     *  'recipientList': string,
-     *  'recipients': array,
-     *  'replyTo': string,
-     *  'rfc822': string,
-     *  'sandbox': boolean,
-     *  'startTime': string | \DateTime,
-     *  'subject': string,
-     *  'substitutionData': array,
-     *  'template': string,
-     *  'text': string,
-     *  'trackClicks': boolean,
-     *  'trackOpens': boolean,
-     *  'transactional': boolean,
-     *  'useDraftTemplate': boolean
-     *
-     * @param array $transmissionConfig
-     *
-     * @return array API repsonse represented as key-value pairs
-     */
-    public function send($transmissionConfig)
-    {
-        if (isset($transmissionConfig['startTime']) && $transmissionConfig['startTime'] instanceof \DateTime) {
-            $transmissionConfig['startTime'] = $transmissionConfig['startTime']->format(\DateTime::ATOM);
-        }
-
-        return $this->create($transmissionConfig);
-    }
-
-    /**
-     * Method for retrieving information about all transmissions
-     *  Wrapper method for a cleaner interface.
-     *
-     * @param null|string $campaignID
-     * @param null|string $templateID
-     *
-     * @return array result Set of transmissions
-     */
-    public function all($campaignID = null, $templateID = null)
-    {
-        $options = [];
-        if ($campaignID !== null) {
-            $options['campaign_id'] = $campaignID;
-        }
-        if ($templateID !== null) {
-            $options['template_id'] = $templateID;
-        }
-
-        return $this->get(null, $options);
-    }
-
-    /**
-     * Method for retrieving information about a single transmission
-     *  Wrapper method for a cleaner interface.
-     *
-     * @param string $transmissionID Identifier of the transmission to be found
-     *
-     * @return array result Single transmission represented in key-value pairs
-     */
-    public function find($transmissionID)
-    {
-        return $this->get($transmissionID);
-    }
-}