/**
 * @workInProgress
 * @ngdoc service
 * @name angular.service.$invalidWidgets
 *
 * @description
 * Keeps references to all invalid widgets found during validation.
 * Can be queried to find whether there are any invalid widgets currently displayed.
 *
 * @example
 */
angularServiceInject("$invalidWidgets", function(){
  var invalidWidgets = [];


  /** Remove an element from the array of invalid widgets */
  invalidWidgets.markValid = function(element){
    var index = indexOf(invalidWidgets, element);
    if (index != -1)
      invalidWidgets.splice(index, 1);
  };


  /** Add an element to the array of invalid widgets */
  invalidWidgets.markInvalid = function(element){
    var index = indexOf(invalidWidgets, element);
    if (index === -1)
      invalidWidgets.push(element);
  };


  /** Return count of all invalid widgets that are currently visible */
  invalidWidgets.visible = function() {
    var count = 0;
    forEach(invalidWidgets, function(widget){
      count = count + (isVisible(widget) ? 1 : 0);
    });
    return count;
  };


  /* At the end of each eval removes all invalid widgets that are not part of the current DOM. */
  this.$onEval(PRIORITY_LAST, function() {
    for(var i = 0; i < invalidWidgets.length;) {
      var widget = invalidWidgets[i];
      if (isOrphan(widget[0])) {
        invalidWidgets.splice(i, 1);
        if (widget.dealoc) widget.dealoc();
      } else {
        i++;
      }
    }
  });


  /**
   * Traverses DOM element's (widget's) parents and considers the element to be an orphant if one of
   * it's parents isn't the current window.document.
   */
  function isOrphan(widget) {
    if (widget == window.document) return false;
    var parent = widget.parentNode;
    return !parent || isOrphan(parent);
  }

  return invalidWidgets;
});
