Using $scope.$watch to respond to game state changes

kahoot-partial-host-controller.js

$scope.$watch('game.data.state', function(newValue, oldValue) {

    switch(newValue) {

      case 'preQuestion':
        $scope.countdown = 5;
        $interval(function() {
          $scope.countdown--;
        },1000, $scope.countdown)
        .then(function() {
          Host.setGameState('question');
        });
        break;

      case 'question':
        $scope.currentQuestion = Host.getCurrentQuestion();
        $scope.answers = Trivia.getPossibleAnswers($scope.currentQuestion);
        $scope.game.data.possibleAnswers = $scope.answers;
        $scope.countdown = 7;
        $interval(function() {
          $scope.countdown--;
        },1000, $scope.countdown)
        .then(function() {
          Host.setGameState('postQuestion');
        });
        break;

      case 'postQuestion':
        $scope.correct = [];
        $scope.currentQuestion = Host.getCurrentQuestion();
        angular.forEach($scope.game.data.users, function(v,k) {
          
          if(Trivia.checkAnswer(Host.getCurrentQuestion().q, v.answer)) {
            v.currentPoints = (v.currentPoints || 0) + 100;
            $scope.correct.push(v.screen_name);
          }
        });
        Host.syncObject.$save();
        break;

      case 'leaderboard':
        $scope.leaderboard = _.map($scope.game.data.users, function(user) {
          return {
            screen_name:user.screen_name,
            current_points:user.currentPoints
          }
        });
    }

  })
});