text: /*****************************************************************************
   * Open MCT, Copyright (c) 2014-2016, United States Government
   * as represented by the Administrator of the National Aeronautics and Space
   * Administration. All rights reserved.
   *
   * Open MCT is licensed under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   * http://www.apache.org/licenses/LICENSE-2.0.
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   *
   * Open MCT includes source code licensed under additional open source
   * licenses. See the Open Source Licenses file (LICENSES.md) included with
   * this source code distribution or the Licensing information page available
   * at runtime from the About dialog for additional information.
   *****************************************************************************/
  
  /**
   * Defines interfaces and common infrastructure for establishing
   * a user's identity.
   * @namespace platform/identity
   */
  define(
      function () {
  
          /**
           * Provides information about the currently logged-in
           * user, if available.
           *
           * @interface IdentityService
           */
  
          /**
           * Get information about the current user. This returns a promise
           * which will resolve to metadata about the user, or undefined if
           * no information about the user is available.
           *
           * @method IdentityService#getUser
           * @returns {Promise.<IdentityMetadata>} a promise for metadata about
           *         the current user
           */
  
          /**
           * Metadata about a user.
           *
           * @typedef IdentityMetadata
           * @property {string} name the user's human-readable name
           * @property {string} key the user's machine-readable name
           */
  
          /**
           * Aggregator for multiple identity services. Exposes the first
           * defined identity provided by any provider, according to
           * priority order.
           *
           * @constructor
           * @implements {IdentityService}
           * @memberof platform/identity
           */
          function IdentityAggregator($q, providers) {
              this.providers = providers;
              this.$q = $q;
          }
  
          function delegateGetUser(provider) {
              return provider.getUser();
          }
  
          function identity(value) {
              return value;
          }
  
          function giveFirst(results) {
              return results.filter(identity)[0];
          }
  
          IdentityAggregator.prototype.getUser = function () {
              var $q = this.$q,
                  promises = this.providers.map(delegateGetUser);
  
              return $q.all(promises).then(giveFirst);
          };
  
          return IdentityAggregator;
      }
  );
  