add bearer auth class

Add a new class inheriting form AuthorizationProvider which enables the use of OAuth2 style tokens for authentication.

Signed-off-by: Matthias Weirich <matthias.weirich@selectcode.de>

javascript/lib/api/src/auth/bearer-auth.ts

@@ -0,0 +1,62 @@
+/*!
+ * Copyright (c) 2019 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+import { AuthProvider, DittoHeaders, DittoURL } from './auth-provider';
+
+/**
+ * Provides OAuth-Style authentication via bearer tokens
+ */
+export abstract class BearerAuth implements AuthProvider {
+
+  /**
+   * The bearer token used for authentication
+   */
+  protected token!: string;
+
+  /**
+   * Build a new instance of bearer auth
+   * @param token The bearer token to be used
+   */
+  constructor(token: string) {
+    this.token = token;
+  }
+
+  abstract authenticateWithHeaders(originalHeaders: DittoHeaders): DittoHeaders;
+
+  abstract authenticateWithUrl(originalUrl: DittoURL): DittoURL;
+}
+
+
+/**
+ * Http implementation of bearer auth using the Authorization HTTP header.
+ */
+export class HttpBearerAuth extends BearerAuth {
+
+  /**
+   * Creates a new instance for HTTP connections
+   * @param token
+   */
+  static newInstance(token: string): HttpBearerAuth {
+    return new HttpBearerAuth(token);
+  }
+
+  authenticateWithUrl(originalUrl: DittoURL): DittoURL {
+    return originalUrl;
+  }
+
+  authenticateWithHeaders(originalHeaders: DittoHeaders): DittoHeaders {
+    return originalHeaders.set('Authorization', `Bearer ${this.token}`);
+  }
+
+}
+