import 'package:flutter/material.dart';
import 'package:html/parser.dart';
import 'package:html/dom.dart' as dom;
import 'package:url_launcher/url_launcher.dart';
import 'package:voyagehandbook/api/classes.dart';
import 'package:voyagehandbook/util/styles.dart';

final _ignoredTags = ["style", "script"];

/// Used to create [TextSpan] from raw HTML from WM API
List<Widget> renderFromPageHTML(RawPage page) {
  var out = <Widget>[
    const SizedBox(
      height: 10,
    ),
    Text(
      page.title,
      textAlign: TextAlign.center,
      style: PageStyles.h1,
    ),
    const SizedBox(
      height: 10,
    ),
    Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        const Text("From"),
        const SizedBox(
          width: 5,
        ),
        GestureDetector(
          onTap: () => launchUrl(
              Uri.parse("https://en.wikivoyage.org/wiki/${page.key}"),
              mode: LaunchMode.externalApplication),
          child: const Text(
            "WikiVoyage",
            style: TextStyle(
              decoration: TextDecoration.underline,
              fontWeight: FontWeight.bold,
            ),
          ),
        ),
      ],
    ),
    Row(
      children: [
        const Text("under"),
        const SizedBox(
          width: 5,
        ),
        GestureDetector(
          onTap: () => launchUrl(Uri.parse(page.license.url),
              mode: LaunchMode.externalApplication),
          child: Text(
            page.license.title,
            style: const TextStyle(
              decoration: TextDecoration.underline,
            ),
          ),
        )
      ],
    )
  ];
  var document = parse(page.html);
  var sections = document.body!.getElementsByTagName("section");
  for (var sec in sections) {
    if (sec.localName == "section") {
      out.addAll(_renderSection(sec));
    }
  }
  return out;
}

List<Widget> _renderSection(dom.Element sec) {
  var out = <Widget>[];
  // Get Section Title
  var headings = sec.children
      .where((element) => ["h2", "h3", "h4", "h5"].contains(element.localName));
  var sectionTitle = (headings.isNotEmpty) ? headings.first : null;
  if (sectionTitle != null) {
    switch (sectionTitle.localName) {
      case "h2":
        out.add(
          const SizedBox(
            height: 10,
          ),
        );
        out.add(Text(sectionTitle.text, style: PageStyles.h2));
        break;
      case "h3":
        out.add(
          Align(
            alignment: Alignment.centerLeft,
            child: Text(
              sectionTitle.text,
              style: PageStyles.h3,
            ),
          ),
        );
        break;
      case "h4":
        out.add(
          Align(
            alignment: Alignment.centerLeft,
            child: Text(sectionTitle.text, style: PageStyles.h4),
          ),
        );
        break;
      case "h5":
        out.add(
          Align(
            alignment: Alignment.centerLeft,
            child: Text(sectionTitle.text, style: PageStyles.h5),
          ),
        );
        break;
      default:
        out.add(
          Align(
            alignment: Alignment.centerLeft,
            child: Text(sectionTitle.text),
          ),
        );
        break;
    }
    // out.add(
    //   const SizedBox(
    //     height: 5,
    //   ),
    // );
  }

  // create TextSpans from text content
  for (var element in sec.children) {
    // Go through all section's children
    for (var t in _ignoredTags) {
      var ignored = element.getElementsByTagName(t);
      if (ignored.isNotEmpty) {
        // Remove ignored tags
        for (var element in ignored) {
          element.remove();
        }
      }
    }

    switch (element.localName) {
      case "p":
      case "link":
        var paraSpans = <TextSpan>[];
        var input = element.innerHtml
            .replaceAll(RegExp(r"<(?!(?:\/b)|(?:\/i)|b|i).+?>"), "")
            .replaceAll("\\n", "\r");
        var noFormatting =
            input.split(RegExp(r"(?:<b .+?>.+?<\/b>)|<i .+?>.+?<\/i>"));
        var needToFormat = RegExp(r"(?:<b .+?>.+?<\/b>)|<i .+?>.+?<\/i>")
            .allMatches(input)
            .toList();
        for (var s in needToFormat) {
          paraSpans.add(TextSpan(
              text: noFormatting[
                  needToFormat.indexOf(s)])); // add text before styled
          var raw = s.group(0)!;
          paraSpans.add(
            TextSpan(
              text: RegExp(r">(.+?)<").firstMatch(raw)!.group(1),
              style: TextStyle(
                fontWeight: (raw.contains("<b")) ? FontWeight.bold : null,
                fontStyle: (raw.contains("<i")) ? FontStyle.italic : null,
              ),
            ),
          ); // add styled
        }
        paraSpans.add(TextSpan(text: noFormatting.last)); // add last
        out.add(RichText(
          text: TextSpan(children: paraSpans),
          textAlign: TextAlign.justify,
        )); // add paragraph spans as single rich text
        out.add(
          const SizedBox(
            height: 5,
          ),
        ); // space paragraphs
        break;
      case "section":
        out.addAll(_renderSection(element));
        break;
      default:
        break;
    }
  }

  out.add(
    const SizedBox(
      height: 5,
    ),
  );
  return out;
}