import {BrowserLocation} from './browser_location';
import {StringWrapper} from 'angular2/src/facade/lang';
import {EventEmitter, ObservableWrapper} from 'angular2/src/facade/async';

export class Location {
  _subject:EventEmitter;
  _browserLocation:BrowserLocation;
  _baseHref:string;
  constructor(browserLocation:BrowserLocation) {
    this._subject = new EventEmitter();
    this._browserLocation = browserLocation;
    this._baseHref = stripIndexHtml(this._browserLocation.getBaseHref());
    this._browserLocation.onPopState((_) => this._onPopState(_));
  }

  _onPopState(_) {
    ObservableWrapper.callNext(this._subject, {
      'url': this.path()
    });
  }

  path() {
    return this.normalize(this._browserLocation.path());
  }

  normalize(url) {
    return this._stripBaseHref(stripIndexHtml(url));
  }

  normalizeAbsolutely(url) {
    if (url[0] != '/') {
      url = '/' + url;
    }
    return this._addBaseHref(url);
  }

  _stripBaseHref(url) {
    if (this._baseHref.length > 0 && StringWrapper.startsWith(url, this._baseHref)) {
      return StringWrapper.substring(url, this._baseHref.length);
    }
    return url;
  }

  _addBaseHref(url) {
    if (!StringWrapper.startsWith(url, this._baseHref)) {
      return this._baseHref + url;
    }
    return url;
  }

  go(url:string) {
    var finalUrl = this.normalizeAbsolutely(url);
    this._browserLocation.pushState(null, '', finalUrl);
  }

  forward() {
    this._browserLocation.forward();
  }

  back() {
    this._browserLocation.back();
  }

  subscribe(onNext, onThrow = null, onReturn = null) {
    ObservableWrapper.subscribe(this._subject, onNext, onThrow, onReturn);
  }
}



function stripIndexHtml(url) {
  // '/index.html'.length == 11
  if (url.length > 10 && StringWrapper.substring(url, url.length - 11) == '/index.html') {
    return StringWrapper.substring(url, 0, url.length - 11);
  }
  return url;
}