import 'package:webfeed/domain/atom_category.dart';
import 'package:webfeed/domain/atom_generator.dart';
import 'package:webfeed/domain/atom_item.dart';
import 'package:webfeed/domain/atom_link.dart';
import 'package:webfeed/domain/atom_person.dart';
import 'package:webfeed/util/datetime.dart';
import 'package:webfeed/util/xml.dart';
import 'package:xml/xml.dart';

class AtomFeed {
  final String id;
  final String title;
  final DateTime updated;
  final List<AtomItem> items;

  final List<AtomLink> links;
  final List<AtomPerson> authors;
  final List<AtomPerson> contributors;
  final List<AtomCategory> categories;
  final AtomGenerator generator;
  final String icon;
  final String logo;
  final String rights;
  final String subtitle;

  AtomFeed({
    this.id,
    this.title,
    this.updated,
    this.items,
    this.links,
    this.authors,
    this.contributors,
    this.categories,
    this.generator,
    this.icon,
    this.logo,
    this.rights,
    this.subtitle,
  });

  factory AtomFeed.parse(String xmlString) {
    var document = XmlDocument.parse(xmlString);
    XmlElement feedElement;
    try {
      feedElement = document.findElements('feed').first;
    } on StateError {
      throw ArgumentError('feed not found');
    }

    return AtomFeed(
      id: findElementOrNull(feedElement, 'id')?.text,
      title: findElementOrNull(feedElement, 'title')?.text,
      updated: parseDateTime(findElementOrNull(feedElement, 'updated')?.text),
      items: feedElement.findElements('entry').map((element) {
        return AtomItem.parse(element);
      }).toList(),
      links: feedElement.findElements('link').map((element) {
        return AtomLink.parse(element);
      }).toList(),
      authors: feedElement.findElements('author').map((element) {
        return AtomPerson.parse(element);
      }).toList(),
      contributors: feedElement.findElements('contributor').map((element) {
        return AtomPerson.parse(element);
      }).toList(),
      categories: feedElement.findElements('category').map((element) {
        return AtomCategory.parse(element);
      }).toList(),
      generator:
          AtomGenerator.parse(findElementOrNull(feedElement, 'generator')),
      icon: findElementOrNull(feedElement, 'icon')?.text,
      logo: findElementOrNull(feedElement, 'logo')?.text,
      rights: findElementOrNull(feedElement, 'rights')?.text,
      subtitle: findElementOrNull(feedElement, 'subtitle')?.text,
    );
  }
}