portainer/app/services/stateManager.js

angular.module('portainer.services')
.factory('StateManager', ['$q', 'SystemService', 'InfoHelper', 'LocalStorage', 'SettingsService', 'StatusService', 'ExtensionManager', 'APPLICATION_CACHE_VALIDITY', function StateManagerFactory($q, SystemService, InfoHelper, LocalStorage, SettingsService, StatusService, ExtensionManager, APPLICATION_CACHE_VALIDITY) {
  'use strict';

  var manager = {};

  var state = {
    loading: true,
    application: {},
    endpoint: {},
    UI: {}
  };

  manager.getState = function() {
    return state;
  };

  manager.clean = function () {
    state.endpoint = {};
  };

  manager.updateLogo = function(logoURL) {
    state.application.logo = logoURL;
    LocalStorage.storeApplicationState(state.application);
  };

  manager.updateExternalContributions = function(displayExternalContributors) {
    state.application.displayExternalContributors = displayExternalContributors;
    LocalStorage.storeApplicationState(state.application);
  };

  manager.updateDonationHeader = function(displayDonationHeader) {
    state.application.displayDonationHeader = displayDonationHeader;
    LocalStorage.storeApplicationState(state.application);
  };

 function assignStateFromStatusAndSettings(status, settings) {
   state.application.authentication = status.Authentication;
   state.application.analytics = status.Analytics;
   state.application.endpointManagement = status.EndpointManagement;
   state.application.version = status.Version;
   state.application.logo = settings.LogoURL;
   state.application.displayDonationHeader = settings.DisplayDonationHeader;
   state.application.displayExternalContributors = settings.DisplayExternalContributors;
   state.application.validity = moment().unix();
 }

  function loadApplicationState() {
    var deferred = $q.defer();

    $q.all({
      settings: SettingsService.publicSettings(),
      status: StatusService.status()
    })
    .then(function success(data) {
      var status = data.status;
      var settings = data.settings;
      assignStateFromStatusAndSettings(status, settings);
      LocalStorage.storeApplicationState(state.application);
      deferred.resolve(state);
    })
    .catch(function error(err) {
      deferred.reject({msg: 'Unable to retrieve server settings and status', err: err});
    })
    .finally(function final() {
      state.loading = false;
    });

    return deferred.promise;
  }

  manager.initialize = function () {
    var deferred = $q.defer();

    var endpointState = LocalStorage.getEndpointState();
    if (endpointState) {
      state.endpoint = endpointState;
    }

    var applicationState = LocalStorage.getApplicationState();
    if (applicationState) {
      var now = moment().unix();
      var cacheValidity = now - applicationState.validity;
      if (cacheValidity > APPLICATION_CACHE_VALIDITY) {
        loadApplicationState()
        .then(function success(data) {
          deferred.resolve(state);
        })
        .catch(function error(err) {
          deferred.reject(err);
        });
      } else {
        state.application = applicationState;
        state.loading = false;
        deferred.resolve(state);
      }
    } else {
      loadApplicationState()
      .then(function success(data) {
        deferred.resolve(state);
      })
      .catch(function error(err) {
        deferred.reject(err);
      });
    }

    return deferred.promise;
  };

  manager.updateEndpointState = function(loading) {
    var deferred = $q.defer();
    if (loading) {
      state.loading = true;
    }
    $q.all({
      info: SystemService.info(),
      version: SystemService.version()
    })
    .then(function success(data) {
      var endpointMode = InfoHelper.determineEndpointMode(data.info);
      var endpointAPIVersion = parseFloat(data.version.ApiVersion);
      state.endpoint.mode = endpointMode;
      state.endpoint.apiVersion = endpointAPIVersion;
      return $q.when(endpointAPIVersion < 1.25 || ExtensionManager.extensions());
    })
    .then(function success(data) {
      state.endpoint.extensions = data instanceof Array ? data : [];
      LocalStorage.storeEndpointState(state.endpoint);
      deferred.resolve();
    })
    .catch(function error(err) {
      deferred.reject({msg: 'Unable to connect to the Docker endpoint', err: err});
    })
    .finally(function final() {
      state.loading = false;
    });

    return deferred.promise;
  };

  return manager;
}]);