Angular 2 decorator

ui-element.ts

export interface UIDecorator {
  footer?: boolean;
  navigator?: UINavbarState;
}

export class UIElement {}

export function UI(meta?: UIDecorator): any {
  let decorator = <(meta?: UIDecorator) => any>makeDecorator(
    'UI',
    <UIDecorator>{
      footer: undefined,
      navigator: undefined
    },
    UIElement
  );

  return function (cls) {
    let onInit = cls.prototype.ngOnInit || function() { };
    let onSetup = cls.prototype.ngOnSetup;

    return (<any>decorator(meta)).Class({
      // extends: Object.prototype.constructor,
      constructor: cls,
      ngOnSetup: function () {
        let state: State = this.state || null;

        const isUIElement = annotation => annotation instanceof UIElement;
        const getAnnotation = annotation => annotation;

        const annotations: any[] = Reflect.getOwnMetadata('annotations', cls);

        const annotation: UIDecorator = head(annotations.filter(isUIElement).map(getAnnotation));

        if (!this.hasOwnProperty('state')) {
          let injector = Framework.getApplicationInjector();
          state = <State>injector.get(State);
        }

        if (annotation.footer) {
          let footer = state.get(SYMBOLS.UI_STATE_FOOTER);
          state.set(SYMBOLS.UI_STATE_FOOTER, merge(footer, { enable: annotation.footer }));
        }

        if (annotation.navigator) {
          let nav = state.get(SYMBOLS.UI_STATE_NAVBAR);
          state.set(SYMBOLS.UI_STATE_NAVBAR, merge(nav, annotation.navigator));
        }
      },
      ngOnInit: function () {
        onInit.call(this);
        onSetup ? onSetup.call(this) : this.ngOnSetup();
      }
    });
  };
}