Directive to show Bootstrap validation errors on submitting a form in AngularJS

gistfile1.js

app.directive('validSubmit', ['$parse', function ($parse) {
    return {
        // we need a form controller to be on the same element as this directive
        // in other words: this directive can only be used on a <form>
        require: 'form',
        // one time action per form
        link: function (scope, element, iAttrs, form) {
            form.$submitted = false;
            // get a hold of the function that handles submission when form is valid
            var fn = $parse(iAttrs.validSubmit);

            // register DOM event handler and wire into Angular's lifecycle with scope.$apply
            element.on('submit', function (event) {
                scope.$apply(function () {
                    // on submit event, set submitted to true (like the previous trick)
                    form.$submitted = true;
                    // if form is valid, execute the submission handler function and reset form submission state
                    if (form.$valid) {
                        fn(scope, { $event: event });
                        form.$submitted = false;
                    }
                });
            });

            element.find('.form-group').each(function () {
                var formGroup = $(this);
                var inputs = formGroup.find('input[ng-model],textarea[ng-model],select[ng-model]');
                if (inputs.length > 0) {
                    inputs.each(function () {
                        var input = $(this);

                        scope.$watch(function () {
                            return input.hasClass('ng-invalid') && (!input.hasClass('ng-pristine') || form.$submitted);
                        }, function (isInvalid) {
                            formGroup.toggleClass('has-error', isInvalid);
                        });
                    });
                }
            });
        }
    };
}]);