API-2195 Add client credentials auth support for PHP SDK (#75)

* API-2195 add methods for client credentials, sample for oauth client credentials

* API-2195 update README

Author: ahongbynder

README.md

@@ -90,6 +90,17 @@ For instance, if we only wanted to retrieve **2 images** here is what the call w
 All the calls are **Asynchronous**, which means they will return a **Promise** object, making it a bit more flexible in order to adjust to any kind of application.
 Again, for a more thorough example there is a sample [application use case](sample/sample.php) in this repo.
 
+### Client Credentials
+
+OAuth can be used via authorization code or client credentials. To use client credentials, initialize a Bynder client 
+with OAuth2 Configuration and make call to get a token via:
+
+`$bynder->getAccessTokenClientCredentials();`
+
+Sample file found in `sample/OAuthClientCredentialsSample.php`.
+
+`php OAuthClientCredentialsSample.php`
+
 ## Methods Available
 These are the methods currently available on the **Bynder PHP SDK**, refer to the [Bynder API Docs](http://docs.bynder.apiary.io/)) for more specific details on the calls.
 

sample/OAuthClientCredentialsSample.php

@@ -0,0 +1,69 @@
+<?php
+require_once(__DIR__ . '/../vendor/autoload.php');
+require_once(__DIR__ . '/sample_config.php');
+use Bynder\Api\BynderClient;
+use Bynder\Api\Impl\OAuth2;
+
+
+try {
+    // instantiate BynderClient, redirectUri and token are null (client credentials)
+    $bynder = new BynderClient(new Oauth2\Configuration(
+        $bynderDomain,
+        null,
+        $clientId,
+        $clientSecret,
+        null,
+        ['timeout' => 5] // Guzzle HTTP request options
+    ));
+
+    // use client credentials grant type to get access token
+    if ($token === null) {
+        $token = $bynder->getAccessTokenClientCredentials();
+    }
+
+    $assetBankManager = $bynder->getAssetBankManager();
+
+    // Get Brands. Returns a Promise.
+    $brandsListPromise = $assetBankManager->getBrands();
+    // Wait for the promise to be resolved.
+    $brandsList = $brandsListPromise->wait();
+
+    if (!empty($brandsList)) {
+        foreach ($brandsList as $brand) {
+            echo("Brand ID: " . $brand['id'] . "\n");
+            var_dump($brand);
+        }
+    }
+
+    // get derivatives
+    $derivativesPromise = $assetBankManager->getDerivatives();
+    $derivativesList = $derivativesPromise->wait();
+
+    if (!empty($derivativesList)) {
+        echo("Derivatives: " . "\n");
+        var_dump($derivativesList);
+    }
+
+    // Get Media Items list.
+    // Optional filter.
+    $query = [
+        'count' => true,
+        'limit' => 10
+    ];
+
+    $mediaListPromise = $assetBankManager->getMediaList($query);
+    $mediaList = $mediaListPromise->wait();
+
+    // outputs list of media items, print media item
+    if (!empty($mediaList) && !empty($mediaList['media'])) {
+        foreach ($mediaList['media'] as $media) {
+            echo("Media ID: " . $media['id'] . "\n");
+            var_dump($media);
+        }
+    }
+} catch (Exception $e) {
+    var_dump($e);
+}
+
+?>
+

src/Bynder/Api/BynderClient.php

@@ -79,6 +79,19 @@ public function getAccessToken($code)
         return $token;
     }
 
+    /**
+     * Returns the Oauth access token using client credentials grant type.
+     *
+     * @return \League\OAuth2\Client\Token\AccessToken
+     */
+    public function getAccessTokenClientCredentials()
+    {
+        $token = $this->requestHandler->getAccessTokenClientCredentials();
+        $this->configuration->setToken($token);
+
+        return $token;
+    }
+
     /**
      * Retrieve all users.
      *

src/Bynder/Api/Impl/OAuth2/RequestHandler.php

@@ -35,6 +35,13 @@ public function getAccessToken($code)
         );
     }
 
+    public function getAccessTokenClientCredentials()
+    {
+        return $this->oauthProvider->getAccessToken(
+            'client_credentials'
+        );
+    }
+
     protected function sendAuthenticatedRequest($requestMethod, $uri, $options = [])
     {
         $this->configuration->refreshToken($this->oauthProvider);