app.config(function($routeProvider) {
  $routeProvider
    .when('/', {
      controller: 'MainCtrl',
      template: 'Allowed from anywhere.<br>Go to main <a href="#/main">page</a>',
      restricted: false
    })
    .when('/main', {
      controller: 'MainCtrl',
      template: 'Allowed from anywhere.<br>Go to restricted <a href="#/restr">page</a>',
      restricted: false
    }).when('/restr', {
      controller: 'RestrictedPageCtrl',
      template: 'Allowed only from main',
      restricted: '/main'
    });
});

app.run(function($rootScope, $location, $route) {
  $rootScope.$on('$locationChangeStart', function(event, next, current) {
    var next = $route.routes[$location.path()];
    var currentPath = current.split('#')[1];
    if (next.restricted && next.restricted !== currentPath) {
      $location.path('/');
      alert('You are trying to reach a restricted page!!!!');
    }
  });
});