Checkbox not working as expected in Angularjs

I have list of items and want to assign checkbox to all these items. I have tried the below code but it's not working as expected. If I click on select all; then only select all is getting checked and if I click on any other items then all items are getting checked.

<div class="select">
   <input type="checkbox" ng-model="selectAll"
      ng-init="selectAll=false;" class="filled-in"
      id="userprofiles"/>
   <label for="userprofiles">Select all</label>
</div>
<ul class="collection">
   <li class="collection-item" ng-repeat="profile in userprofiles">
      <input ng-model="user.profile"
         ng-init="user.profile=false"
         class="filled-in" type="checkbox"
         id="userprofile"
         value=""/>
      <label for="userprofile"> </label>
   </li>
</ul>

Controller.js:

  $scope.user.profile = [];
    $scope.$watch('selectAll', function(newValue, oldValue) {
        angular.forEach($scope.userprofiles, function(selected, item) {
            $scope.user.profile[item] = newValue;
        });
    });