Add base OAuth2 controller

framework/core/composer.json

@@ -35,6 +35,7 @@
         "illuminate/validation": "5.1.*",
         "illuminate/view": "5.1.*",
         "league/flysystem": "^1.0.11",
+        "league/oauth2-client": "~1.0",
         "tobscure/json-api": "^0.2.0",
         "oyejorge/less.php": "~1.5",
         "intervention/image": "^2.3.0",

framework/core/src/Forum/Controller/AbstractOAuth2Controller.php

@@ -0,0 +1,94 @@
+<?php
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Forum\Controller;
+
+use Flarum\Forum\AuthenticationResponseFactory;
+use Flarum\Http\Controller\ControllerInterface;
+use League\OAuth2\Client\Provider\ResourceOwnerInterface;
+use Psr\Http\Message\ServerRequestInterface as Request;
+use Zend\Diactoros\Response\HtmlResponse;
+use Zend\Diactoros\Response\RedirectResponse;
+
+abstract class AbstractOAuth2Controller implements ControllerInterface
+{
+    /**
+     * @var AuthenticationResponseFactory
+     */
+    protected $authResponse;
+
+    /**
+     * @param AuthenticationResponseFactory $authResponse
+     */
+    public function __construct(AuthenticationResponseFactory $authResponse)
+    {
+        $this->authResponse = $authResponse;
+    }
+
+    /**
+     * @param Request $request
+     * @return \Psr\Http\Message\ResponseInterface|RedirectResponse
+     */
+    public function handle(Request $request)
+    {
+        $redirectUri = (string) $request->getUri()->withQuery('');
+
+        $provider = $this->getProvider($redirectUri);
+
+        $session = $request->getAttribute('session');
+
+        $queryParams = $request->getQueryParams();
+        $code = array_get($queryParams, 'code');
+        $state = array_get($queryParams, 'state');
+
+        if (! $code) {
+            $authUrl = $provider->getAuthorizationUrl($this->getAuthorizationUrlOptions());
+            $session->set('oauth2state', $provider->getState());
+
+            return new RedirectResponse($authUrl.'&display=popup');
+        } elseif (! $state || $state !== $session->get('oauth2state')) {
+            $session->forget('oauth2state');
+            echo 'Invalid state. Please close the window and try again.';
+            exit;
+        }
+
+        $token = $provider->getAccessToken('authorization_code', compact('code'));
+
+        $owner = $provider->getResourceOwner($token);
+
+        $identification = $this->getIdentification($owner);
+        $suggestions = $this->getSuggestions($owner);
+
+        return $this->authResponse->make($request, $identification, $suggestions);
+    }
+
+    /**
+     * @param string $redirectUri
+     * @return \League\OAuth2\Client\Provider\AbstractProvider
+     */
+    abstract protected function getProvider($redirectUri);
+
+    /**
+     * @return array
+     */
+    abstract protected function getAuthorizationUrlOptions();
+
+    /**
+     * @param ResourceOwnerInterface $resourceOwner
+     * @return array
+     */
+    abstract protected function getIdentification(ResourceOwnerInterface $resourceOwner);
+
+    /**
+     * @param ResourceOwnerInterface $resourceOwner
+     * @return array
+     */
+    abstract protected function getSuggestions(ResourceOwnerInterface $resourceOwner);
+}