import {Directive, onAllChangesDone} from 'angular2/src/core/annotations_impl/annotations';
import {ElementRef} from 'angular2/core';
import {StringMap, StringMapWrapper} from 'angular2/src/facade/collection';

import {isPresent} from 'angular2/src/facade/lang';
import {DOM} from 'angular2/src/dom/dom_adapter';

import {Router} from './router';
import {Location} from './location';

/**
 * The RouterLink directive lets you link to specific parts of your app.
 *
 *
 * Consider the following route configuration:

 * ```
 * @RouteConfig({
 *   path: '/user', component: UserCmp, alias: 'user'
 * });
 * class MyComp {}
 * ```
 *
 * When linking to a route, you can write:
 *
 * ```
 * <a router-link="user">link to user component</a>
 * ```
 *
 * @exportedAs angular2/router
 */
@Directive({
  selector: '[router-link]',
  properties: [
    'route: routerLink',
    'params: routerParams'
  ],
  lifecycle: [onAllChangesDone]
})
export class RouterLink {
  _domEl;
  _route:string;
  _params:StringMap<string, string>;
  _router:Router;
  _location:Location;
  // the url displayed on the anchor element.
  _visibleHref: string;
  // the url passed to the router navigation.
  _navigationHref: string;

  constructor(elementRef:ElementRef, router:Router, location:Location) {
    this._domEl = elementRef.domElement;
    this._router = router;
    this._location = location;
    this._params = StringMapWrapper.create();
    DOM.on(this._domEl, 'click', (evt) => {
      DOM.preventDefault(evt);
      this._router.navigate(this._navigationHref);
    });
  }

  set route(changes: string) {
    this._route = changes;
  }

  set params(changes: StringMap) {
    this._params = changes;
  }

  onAllChangesDone(): void {
    if (isPresent(this._route) && isPresent(this._params)) {
      this._navigationHref = this._router.generate(this._route, this._params);
      this._visibleHref = this._location.normalizeAbsolutely(this._navigationHref);
      // Keeping the link on the element to support contextual menu `copy link`
      // and other in-browser affordances.
      DOM.setAttribute(this._domEl, 'href', this._visibleHref);
    }
  }
}