(function () {
  "use strict";

  var name = 'adAutosave';
  angular.module('app.directive')

    .constant('adAutosaveConfig', {
      timeout: 750
    })


  /**
   * ad-autosave="onSave"               {Function: promise}
   * ad-autosave-timeout="750"          {?Number}   override adAutosaveConfig.timeout
   */
    .directive('adAutosave', ['$parse', 'adAutosaveConfig', 'debounce', function ($parse, adAutosaveConfig, debounce) {

      return {
        require: 'ngModel',
        link: function (scope, element, attr, ctrl) {
          var getAttrReflection = function (name, defValue) {
            var exprDefined = angular.isDefined(attr[name]), expr;
            if (exprDefined || angular.isDefined(defValue)) {
              expr = exprDefined ? $parse(attr[name]) : null;
              return function (locals) {
                return expr ? expr(scope, locals) : defValue;
              };
            }
            return null;
          };

          var attrAutosave = getAttrReflection(name);
          var timeout = getAttrReflection(name + 'Timeout', adAutosaveConfig.timeout)();

          ctrl.$autosaving = false;
          ctrl.$autosaveValue = ctrl.$modelValue;
          var autosaveStart = function () {
            ctrl.$autosaving = true;
            ctrl.$autosaveValue = ctrl.$modelValue;
          };
          var autosaveDone = function () {
            ctrl.$autosaving = false;
            ctrl.$setPristine();
          };
          var triggerSave = function () {
            var promise;
            if (ctrl.$valid && ctrl.$dirty && ctrl.$modelValue !== ctrl.$autosaveValue) {
              autosaveStart();
              promise = attrAutosave({value: ctrl.$modelValue});
              if (promise && angular.isFunction(promise.then)) {
                promise.then(autosaveDone, autosaveDone);
              }
            }
          };

          (timeout && timeout > 0) && ctrl.$viewChangeListeners.push(debounce(triggerSave, timeout));
          element.on('blur', triggerSave);
          element.on('$destroy', element.off.bind(element, 'blur', triggerSave));
        }
      };
    }]);

})();