import {Animation} from '../animations/animation';
import {raf} from '../util/dom';

const SHOW_NAVBAR_CSS = 'show-navbar';
const SHOW_VIEW_CSS = 'show-view';


let registry = {};

export class Transition extends Animation {

  constructor(nav, opts) {
    super();

    // get the entering and leaving items
    let enteringItem = this.entering = nav.getStagedEnteringItem();
    let leavingItem = this.leaving = nav.getStagedLeavingItem();

    // create animation for the entering item's "ion-view" element
    this.enteringView = new Animation(enteringItem.viewElement());
    this.enteringView.beforePlay.addClass(SHOW_VIEW_CSS);
    this.addAnimation(this.enteringView);

    // create animation for the entering item's "ion-navbar" element
    if (opts.navbar !== false) {
      this.enteringNavbar = new Animation(enteringItem.navbarElement());
      this.enteringNavbar.beforePlay.addClass(SHOW_NAVBAR_CSS);

      // create animation for the entering item's "ion-title" element
      this.enteringTitle = new Animation(enteringItem.titleElement());
      this.enteringNavbar.addAnimation(this.enteringTitle);
      this.addAnimation(this.enteringNavbar);
    }

    if (leavingItem) {
      // create animation for the entering item's "ion-view" element
      this.leavingView = new Animation(leavingItem.viewElement());
      this.leavingView.afterFinish.removeClass(SHOW_VIEW_CSS);

      // create animation for the entering item's "ion-navbar" element
      this.leavingNavbar = new Animation(leavingItem.navbarElement());
      this.leavingNavbar.afterFinish.removeClass(SHOW_NAVBAR_CSS);

      // create animation for the leaving item's "ion-title" element
      this.leavingTitle = new Animation(leavingItem.titleElement());
      this.leavingNavbar.addAnimation(this.leavingTitle);

      this.addAnimation(this.leavingView, this.leavingNavbar);
    }

  }

  stage(callback) {
    raf(callback);
  }


  /*
   STATIC CLASSES
   */
  static create(nav, opts = {}) {
    let name = opts.animation || 'ios';

    let TransitionClass = registry[name];
    if (!TransitionClass) {
      // transition wasn't found, default to a 'none' transition
      // which doesn't animate anything, just shows and hides
      TransitionClass = Transition;
    }

    return new TransitionClass(nav, opts);
  }

  static register(name, TransitionClass) {
    registry[name] = TransitionClass;
  }

}