Allow to start authorization code flow with a given identifier

This complements the metadata feature, since it allows to create
an identifier for use with the authorization code flow as well as
setting metadata on the authorization being handled.

Author: kdambekalns

Classes/OAuthClient.php

@@ -248,6 +248,18 @@ public function requestAccessToken(string $serviceName, string $clientId, string
         $this->entityManager->flush();
     }
 
+    /**
+     * Returns an authorization id taking the service type and service name into account.
+     *
+     * @param string $clientId
+     * @return string
+     * @throws OAuthClientException
+     */
+    public function generateAuthorizationIdForAuthorizationCodeGrant(string $clientId)
+    {
+        return Authorization::generateAuthorizationIdForAuthorizationCodeGrant($this->getServiceType(), $this->getServiceName(), $clientId);
+    }
+
     /**
      * Start OAuth authorization with the Authorization Code flow
      *
@@ -260,7 +272,22 @@ public function requestAccessToken(string $serviceName, string $clientId, string
      */
     public function startAuthorization(string $clientId, string $clientSecret, UriInterface $returnToUri, string $scope): UriInterface
     {
-        $authorizationId = Authorization::generateAuthorizationIdForAuthorizationCodeGrant($this->getServiceType(), $this->getServiceName(), $clientId);
+        $authorizationId = $this->generateAuthorizationIdForAuthorizationCodeGrant($clientId);
+        return $this->startAuthorizationWithId($authorizationId, $clientId, $clientSecret, $returnToUri, $scope);
+    }
+
+    /**
+     * Start OAuth authorization with the Authorization Code flow
+     *
+     * @param string $clientId The client id, as provided by the OAuth server
+     * @param string $clientSecret The client secret, provided by the OAuth server
+     * @param UriInterface $returnToUri URI to return to when authorization is finished
+     * @param string $scope Scope to request for authorization. Must be scope ids separated by space, e.g. "openid profile email"
+     * @return UriInterface The URL the browser should redirect to, asking the user to authorize
+     * @throws OAuthClientException
+     */
+    public function startAuthorizationWithId(string $authorizationId, string $clientId, string $clientSecret, UriInterface $returnToUri, string $scope): UriInterface
+    {
         $authorization = new Authorization($authorizationId, $this->getServiceType(), $clientId, Authorization::GRANT_AUTHORIZATION_CODE, $scope);
         $this->logger->info(sprintf('OAuth (%s): Starting authorization %s using client id "%s", a %s bytes long secret and scope "%s".', $this->getServiceType(), $authorization->getAuthorizationId(), $clientId, strlen($clientSecret), $scope));