$(function() {
  var fieldsCount,
      maxFieldsCount = 4,
      $addLink = $('a.add_nested_fields');
  function toggleAddLink() {
    $addLink.toggle(fieldsCount <= maxFieldsCount)
  }
  $(document).on('nested:fieldAdded', function() {
    fieldsCount += 1;
    toggleAddLink();
  });
  $(document).on('nested:fieldRemoved', function() {
    fieldsCount -= 1;
    toggleAddLink();
  });  
  // count existing nested fields after page was loaded
  fieldsCount = $('form .fields').length;
  toggleAddLink();
})

$(function() {
  $(document).on('nested:fieldAdded', function(e) {
    var link = $(e.currentTarget.activeElement);
    if (!link.data('limit')) {
      return;
    }
    if (link.siblings('.fields:visible').length >= link.data('limit')) {
      link.hide();
    }
  });
  $(document).on('nested:fieldRemoved', function(e) {
    var link = $(e.target).siblings('a.add_nested_fields');
    if (!link.data('limit')) {
      return;
    }
    if (link.siblings('.fields:visible').length < link.data('limit')) {
      link.show();
    }
  });
})