import 'dart:html' as html show HttpRequest, Element, querySelector;

import 'package:html/parser.dart' show parse;
import 'package:html/dom.dart' as dom show Element;

final excluded_keywords = ['index', 'CONTRIBUTING', 'LICENSE', 'README'];

// Get the sitemap content
Future<String> fetchRemoteSitemap() async {
  const path = 'sitemap.html';
  try {
    return await html.HttpRequest.getString(path);
  } catch (e) {
    print('Couldn’t open $path');
  }
  return 'Error';
}

// Parse the list of elements and detect pages from this list
Map<String, String> detectPages(List<dom.Element> sitemap, [String prefix]) {
  final links = <String, String>{};
  for (var elem in sitemap) {
    for (var kw in excluded_keywords) {
      if (elem.outerHtml.contains(kw)) {
        continue;
      }
    }
    if (elem.innerHtml.startsWith('<a')) {
      elem = elem.firstChild;
      final url = elem.attributes['href'];
      final text = elem.firstChild.text;
      links[url] = (prefix == null) ? text : '$text ($prefix)';
    } else {
      final prefix = elem.firstChild.text;
      final ul = elem.children[0].children;
      links.addAll(detectPages(ul, prefix));
    }
  }
  return links;
}

// This function returns a Map which contains all links to languages detected
// from the sitemap.
Future<Map<String, String>> parseSitemap() async {
  final content = await fetchRemoteSitemap();
  final sitemap = parse(content).getElementsByClassName('org-ul')[0].children;
  return detectPages(sitemap);
}

Future sleep(Duration time) async {
  return Future.delayed(time);
}

Future<html.Element> getSitemap() async {
  final sitemap = await parseSitemap();
  final pages = <html.Element>[];
  sitemap.forEach((url, name) {
    final link = html.Element.li()
      ..classes.add('dropdown-item')
      ..append(html.Element.a()
        ..attributes['href'] = url
        ..innerText = name);
    pages.add(link);
  });
  var drop_container;
  do {
    await sleep(Duration(seconds: 1));
    drop_container = html.querySelector('#drop-page');
  } while (drop_container != null);
  pages.forEach((link) => drop_container.append(link));
}