Add oauth token method

README.md

@@ -165,6 +165,12 @@ public function createDocument(array $parameters)
 public function createDocumentDownloadUrl(string $identifier, CarbonInterface $expiresAt = NULL)
 ```
 
+### Oauth
+
+```php
+public function retrievingToken(string $grantType, array $attributes)
+```
+
 ### PaymentIntents
 
 ```php

src/GhostZero/BitinflowAccounts/BitinflowAccounts.php

@@ -20,6 +20,7 @@ class BitinflowAccounts
 
     use Traits\ChargesTrait;
     use Traits\DocumentsTrait;
+    use Traits\OauthTrait;
     use Traits\PaymentIntentsTrait;
     use Traits\SshKeysTrait;
     use Traits\UsersTrait;

src/GhostZero/BitinflowAccounts/Traits/OauthTrait.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace GhostZero\BitinflowAccounts\Traits;
+
+use GhostZero\BitinflowAccounts\Result;
+use GuzzleHttp\Exception\RequestException;
+
+/**
+ * @author René Preuß <rene@preuss.io>
+ */
+trait OauthTrait
+{
+
+    /**
+     * Retrieving a oauth token using a given grant type.
+     *
+     * @param string $grantType
+     * @param array  $attributes
+     *
+     * @return Result
+     */
+    public function retrievingToken(string $grantType, array $attributes): Result
+    {
+        try {
+            $response = $this->client->request('POST', '/oauth/token', $attributes + [
+                    'form_params' => [
+                        'grant_type' => $grantType,
+                        'client_id' => $this->getClientId(),
+                        'client_secret' => $this->getClientSecret(),
+                    ],
+                ]);
+
+            $result = new Result($response, null);
+        } catch (RequestException $exception) {
+            $result = new Result($exception->getResponse(), $exception);
+        }
+
+        $result->bitinflow = $this;
+
+        return $result;
+    }
+}

tests/GhostZero/BitinflowAccounts/ApiOauthTest.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace GhostZero\BitinflowAccounts\Tests;
+
+use GhostZero\BitinflowAccounts\Tests\TestCases\ApiTestCase;
+
+/**
+ * @author René Preuß <rene@preuss.io>
+ */
+class ApiOauthTest extends ApiTestCase
+{
+
+    public function testGetOauthToken(): void
+    {
+        $this->getClient()->withClientId('5');
+        $this->getClient()->withClientSecret('jejmtAJJWeEesW1siWwojjLn6zW9AIcWH1wqfFPq');
+        $this->registerResult($result = $this->getClient()->retrievingToken('client_credentials', [
+            'scope' => '',
+        ]));
+        $this->assertTrue($result->success());
+        $this->assertNotEmpty($result->data()->access_token);
+    }
+}