device code response class

lib/src/response.dart

@@ -23,3 +23,51 @@ class AuthorizationTokenResponse {
     return map;
   }
 }
+
+/// Represents the response for an OAuth2 `device_code` request.
+class DeviceCodeResponse {
+  /// REQUIRED. The device verification code.
+  final String deviceCode;
+
+  /// REQUIRED. The end-user verification code.
+  final String userCode;
+
+  /// REQUIRED. The end-user verification URI on the authorization
+  /// server. The URI should be short and easy to remember as end users
+  /// will be asked to manually type it into their user-agent.
+  final Uri verificationUri;
+
+  /// OPTIONAL.  A verification URI that includes the [userCode] (or
+  /// other information with the same function as the [userCode]),
+  /// designed for non-textual transmission.
+  final Uri verificationUriComplete;
+
+  /// OPTIONAL.  The minimum amount of time in seconds that the client
+  /// SHOULD wait between polling requests to the token endpoint.  If no
+  /// value is provided, clients MUST use 5 as the default.
+  final int interval;
+
+  /// The lifetime, in *seconds* of the [deviceCode] and [userCode].
+  final int expiresIn;
+
+  const DeviceCodeResponse(
+      this.deviceCode, this.userCode, this.verificationUri, this.expiresIn,
+      {this.verificationUriComplete, this.interval});
+
+  Map<String, dynamic> toJson() {
+    var out = <String, dynamic>{
+      'device_code': deviceCode,
+      'user_code': userCode,
+      'verification_uri': verificationUri.toString(),
+    };
+
+    if (verificationUriComplete != null) {
+      out['verification_uri_complete'] = verificationUriComplete.toString();
+    }
+
+    if (interval != null) out['interval'] = interval;
+    if (expiresIn != null) out['expires_in'] = expiresIn;
+
+    return out;
+  }
+}

lib/src/server.dart

@@ -6,7 +6,7 @@ import 'response.dart';
 import 'token_type.dart';
 
 /// A request handler that performs an arbitrary authorization token grant.
-typedef Future<AuthorizationTokenResponse> ExtensionGrant(
+typedef FutureOr<AuthorizationTokenResponse> ExtensionGrant(
     RequestContext req, ResponseContext res);
 
 Future<String> _getParam(RequestContext req, String name, String state,
@@ -62,12 +62,12 @@ abstract class AuthorizationServer<Client, User> {
   FutureOr<Client> findClient(String clientId);
 
   /// Verify that a [client] is the one identified by the [clientSecret].
-  Future<bool> verifyClient(Client client, String clientSecret);
+  FutureOr<bool> verifyClient(Client client, String clientSecret);
 
   /// Prompt the currently logged-in user to grant or deny access to the [client].
   ///
   /// In many applications, this will entail showing a dialog to the user in question.
-  requestAuthorizationCode(
+  FutureOr requestAuthorizationCode(
       Client client,
       String redirectUri,
       Iterable<String> scopes,