Add oauth token method

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;
+    }
+}