Added Yammer OAuth2 Provider

app/config/providers.php

@@ -231,6 +231,16 @@ return [ // Ordered by ABC.
         'beta' => false,
         'mock' => false,
     ],
+    'yammer' => [
+        'name' => 'Yammer',
+        'developers' => 'https://developer.yammer.com/docs/oauth-2',
+        'icon' => 'icon-yammer',
+        'enabled' => true,
+        'sandbox' => false,
+        'form' => false,
+        'beta' => false,
+        'mock' => false,
+    ],
     'yandex' => [
         'name' => 'Yandex',
         'developers' => 'https://tech.yandex.com/oauth/',

src/Appwrite/Auth/OAuth2/Yammer.php

@@ -0,0 +1,137 @@
+<?php
+
+namespace Appwrite\Auth\OAuth2;
+
+use Appwrite\Auth\OAuth2;
+
+// Reference Material
+// https://developer.yammer.com/docs/oauth-2
+
+class Yammer extends OAuth2
+{
+    /**
+     * @var string
+     */
+    private $endpoint = 'https://www.yammer.com/oauth2/';
+
+    /**
+     * @var array
+     */
+    protected $user = [];
+
+    /**
+     * @return string
+     */
+    public function getName(): string
+    {
+        return 'yammer';
+    }
+
+    /**
+     * @return string
+     */
+    public function getLoginURL(): string
+    {
+        return $this->endpoint . 'oauth2/authorize?'.
+        \http_build_query([
+            'client_id' => $this->appID,
+            'response_type' => 'code',
+            'redirect_uri' => $this->callback,
+            'state' => \json_encode($this->state)
+        ]);
+    }
+
+    /**
+     * @param string $code
+     *
+     * @return string
+     */
+    public function getAccessToken(string $code): string
+    {
+        $headers = ['Content-Type: application/x-www-form-urlencoded'];
+
+        $accessToken = $this->request(
+            'POST',
+            $this->endpoint . 'access_token?',
+            $headers,
+            \http_build_query([
+                'client_id' => $this->appID,
+                'client_secret' => $this->appSecret,
+                'code' => $code,
+                'grant_type' => 'authorization_code'
+            ])
+        );
+
+        $accessToken = \json_decode($accessToken, true);
+
+        if (isset($accessToken['access_token']['token'])) {
+            return $accessToken['access_token']['token'];
+        }
+
+        return '';
+    }
+
+    /**
+     * @param string $accessToken
+     *
+     * @return string
+     */
+    public function getUserID(string $accessToken): string
+    {
+        $user = $this->getUser($accessToken);
+
+        if (isset($user['id'])) {
+            return $user['id'];
+        }
+
+        return '';
+    }
+
+    /**
+     * @param string $accessToken
+     *
+     * @return string
+     */
+    public function getUserEmail(string $accessToken): string
+    {
+        $user = $this->getUser($accessToken);
+
+        if (isset($user['email'])) {
+            return $user['email'];
+        }
+        
+        return '';
+    }
+
+    /**
+     * @param string $accessToken
+     *
+     * @return string
+     */
+    public function getUserName(string $accessToken): string
+    {
+        $user = $this->getUser($accessToken);
+
+        if (isset($user['full_name'])) {
+            return $user['full_name'];
+        }
+        
+        return '';
+    }
+
+    /**
+     * @param string $accessToken
+     *
+     * @return array
+     */
+    protected function getUser(string $accessToken): array
+    {
+        if (empty($this->user)) {
+            $headers = ['Authorization: Bearer '. \urlencode($accessToken)];
+            $user = $this->request('GET', 'https://www.yammer.com/api/v1/users/current.json', $headers);
+            $this->user = \json_decode($user, true);
+        }
+
+        return $this->user;
+    }
+}