import 'package:easy_localization/easy_localization.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:gap/gap.dart';
import 'package:html/dom.dart' as dom;
import 'package:html/parser.dart';
import 'package:provider/provider.dart';
import 'package:relative_time/relative_time.dart';
import 'package:styled_widget/styled_widget.dart';
import 'package:surface/providers/sn_network.dart';
import 'package:surface/types/news.dart';
import 'package:surface/widgets/dialog.dart';
import 'package:surface/widgets/navigation/app_scaffold.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:surface/widgets/universal_image.dart';
import 'package:url_launcher/url_launcher_string.dart';

class NewsDetailScreen extends StatefulWidget {
  final String hash;

  const NewsDetailScreen({super.key, required this.hash});

  @override
  State<NewsDetailScreen> createState() => _NewsDetailScreenState();
}

class _NewsDetailScreenState extends State<NewsDetailScreen> {
  SnNewsArticle? _article;
  dom.Document? _articleFragment;

  Future<void> _fetchArticle() async {
    try {
      final sn = context.read<SnNetworkProvider>();
      final resp = await sn.client.get('/cgi/re/news/${widget.hash}');
      _article = SnNewsArticle.fromJson(resp.data);
      _articleFragment = parse(_article!.content);
    } catch (err) {
      if (!mounted) return;
      context.showErrorDialog(err).then((_) {
        if (!mounted) return;
        Navigator.pop(context);
      });
    } finally {
      setState(() {});
    }
  }

  List<Widget> _parseHtmlToWidgets(Iterable<dom.Element>? elements) {
    if (elements == null) return [];

    final List<Widget> widgets = [];

    for (final node in elements) {
      switch (node.localName) {
        case 'h1':
        case 'h2':
        case 'h3':
        case 'h4':
        case 'h5':
        case 'h6':
          widgets.add(Text(node.text.trim(), style: Theme.of(context).textTheme.titleMedium));
          break;
        case 'p':
          if (node.text.trim().isEmpty) continue;
          widgets.add(
            Text.rich(
              TextSpan(
                text: node.text.trim(),
                children: [
                  for (final child in node.children)
                    switch (child.localName) {
                      'a' => TextSpan(
                          text: child.text.trim(),
                          style: const TextStyle(decoration: TextDecoration.underline),
                          recognizer: TapGestureRecognizer()
                            ..onTap = () {
                              launchUrlString(child.attributes['href']!);
                            },
                        ),
                      _ => TextSpan(text: child.text.trim()),
                    },
                ],
              ),
              style: Theme.of(context).textTheme.bodyLarge,
            ),
          );
          break;
        case 'a':
          // drop single link
          break;
        case 'div':
          // ignore div text, normally it is not meaningful
          widgets.addAll(_parseHtmlToWidgets(node.children));
          break;
        case 'hr':
          widgets.add(const Divider());
          break;
        case 'img':
          var src = node.attributes['src'];
          if (src == null) break;
          final width = double.tryParse(node.attributes['width'] ?? 'null');
          final height = double.tryParse(node.attributes['height'] ?? 'null');
          final ratio = width != null && height != null ? width / height : 1.0;
          if (src.startsWith('//')) {
            src = 'https:$src';
          } else if (!src.startsWith('http')) {
            final baseUri = Uri.parse(_article!.url);
            final baseUrl = '${baseUri.scheme}://${baseUri.host}';
            src = '$baseUrl/$src';
          }
          widgets.add(
            AspectRatio(
              aspectRatio: ratio,
              child: Container(
                decoration: BoxDecoration(
                  borderRadius: BorderRadius.all(Radius.circular(8)),
                  border: Border.all(
                    color: Theme.of(context).dividerColor,
                    width: 1,
                  ),
                ),
                height: height ?? double.infinity,
                child: ClipRRect(
                  borderRadius: BorderRadius.all(Radius.circular(8)),
                  child: Container(
                    color: Theme.of(context).colorScheme.surfaceContainer,
                    child: AutoResizeUniversalImage(
                      src,
                      fit: width != null && height != null ? BoxFit.cover : BoxFit.contain,
                    ),
                  ),
                ),
              ),
            ),
          );
          break;
        default:
          widgets.addAll(_parseHtmlToWidgets(node.children));
          break;
      }
    }

    return widgets;
  }

  @override
  void initState() {
    super.initState();
    _fetchArticle();
  }

  bool _isReadingFromReader = true;

  @override
  Widget build(BuildContext context) {
    return AppScaffold(
      appBar: AppBar(
        leading: const PageBackButton(),
        title: Text(_article?.title ?? 'loading'.tr()),
      ),
      body: Column(
        children: [
          MaterialBanner(
            dividerColor: Colors.transparent,
            leading: const Icon(Icons.info),
            content: Text(_isReadingFromReader ? 'newsReadingFromReader'.tr() : 'newsReadingFromOriginal'.tr()),
            actions: [
              TextButton(
                child: Text('newsReadingProviderSwap').tr(),
                onPressed: () {
                  setState(() => _isReadingFromReader = !_isReadingFromReader);
                },
              ),
            ],
          ),
          if (_articleFragment != null && _isReadingFromReader)
            Expanded(
              child: SingleChildScrollView(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  spacing: 8,
                  children: [
                    Text(_article!.title, style: Theme.of(context).textTheme.titleLarge),
                    Builder(builder: (context) {
                      final htmlDescription = parse(_article!.description);
                      return Text(
                        htmlDescription.children.map((ele) => ele.text.trim()).join(),
                        style: Theme.of(context).textTheme.bodyMedium,
                      );
                    }),
                    Builder(builder: (context) {
                      final date = _article!.publishedAt ?? _article!.createdAt;
                      return Row(
                        spacing: 2,
                        children: [
                          Text(DateFormat().format(date)).textStyle(Theme.of(context).textTheme.bodySmall!),
                          Text(' · ').textStyle(Theme.of(context).textTheme.bodySmall!).bold(),
                          Text(RelativeTime(context).format(date)).textStyle(Theme.of(context).textTheme.bodySmall!),
                        ],
                      ).opacity(0.75);
                    }),
                    Text('newsDisclaimer').tr().textStyle(Theme.of(context).textTheme.bodySmall!).opacity(0.75),
                    const Divider(),
                    ..._parseHtmlToWidgets(_articleFragment!.children),
                    const Divider(),
                    InkWell(
                      child: Row(
                        mainAxisSize: MainAxisSize.min,
                        children: [
                          Text(
                            'Reference from original website',
                            style: TextStyle(decoration: TextDecoration.underline),
                          ),
                          const Gap(4),
                          Icon(Icons.launch, size: 16),
                        ],
                      ).opacity(0.85),
                      onTap: () {
                        launchUrlString(_article!.url);
                      },
                    ),
                    Gap(MediaQuery.of(context).padding.bottom),
                  ],
                ).padding(horizontal: 12, vertical: 16),
              ),
            )
          else if (_article != null)
            Expanded(
              child: InAppWebView(
                key: GlobalKey(),
                initialUrlRequest: URLRequest(url: WebUri(_article!.url)),
              ),
            ),
        ],
      ),
    );
  }
}