voyagehandbook/lib/util/render.dart

import 'package:cached_network_image/cached_network_image.dart';
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';
import 'package:voyagehandbook/util/widgets/warning.dart';
import 'package:html_unescape/html_unescape_small.dart';

/*
        Voyage Handbook - The open-source WikiVoyage reader
        Copyright (C) 2023 Matyáš Caras

        This program is free software: you can redistribute it and/or modify
        it under the terms of the GNU General Public License as published by
        the Free Software Foundation, either version 3 of the License.

        This program is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        GNU General Public License for more details.

        You should have received a copy of the GNU General Public License
        along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

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

/// Used to create Widgets from raw HTML from WM API
ListView renderFromPageHTML(RawPage page, double height, double width) {
  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, height, width));
    }
  }
  var l = ListView.builder(
    padding: EdgeInsets.zero,
    itemBuilder: (c, i) => out[i],
    itemCount: out.length,
  );
  return l;
}

List<Widget> _renderSection(dom.Element sec, double height, double width) {
  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,
          textAlign: TextAlign.center,
        ));
        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":
        out.add(
          RichText(
            text: TextSpan(children: _renderText(element.innerHtml)),
            textAlign: TextAlign.justify,
          ),
        ); // add paragraph spans as single rich text
        out.add(
          const SizedBox(
            height: 5,
          ),
        ); // space paragraphs
        break;
      case "figure":

        /// Image figure
        var imgs = element.getElementsByTagName("img");
        if (imgs.isEmpty) break;
        var img = imgs.first; // get image element
        if (img.attributes["src"] == null) break;
        var figcap = element.getElementsByTagName("figcaption"); // get caption
        String? caption;
        if (figcap.isNotEmpty) {
          caption = figcap.first.text; // TODO: handle links
        }
        out.add(const SizedBox(
          height: 10,
        ));
        out.add(
          Container(
            // TODO: add tap detector to open wikimedia page?
            width: width * 0.8,
            height: height * 0.3,
            foregroundDecoration: BoxDecoration(
              image: DecorationImage(
                fit: BoxFit.fitHeight,
                image: CachedNetworkImageProvider(
                  img.attributes["src"]!.replaceAll("//", "https://"),
                ),
              ),
            ),
            //height: height * 0.3,
          ),
        ); // load image
        if (caption != null) {
          // Add caption when available
          out.add(
            const SizedBox(
              height: 3,
            ),
          );
          out.add(Text(
            caption,
            textAlign: TextAlign.center,
          ));
        }
        out.add(
          const SizedBox(
            height: 10,
          ),
        );
        break;
      case "section":
        out.addAll(_renderSection(element, height, width));
        break;
      case "div":
        if (element.attributes["class"] != null &&
            element.attributes["class"] == "pp_cautionbox") {
          out.add(_renderWarning(element));
          out.add(
            const SizedBox(
              height: 10,
            ),
          );
        }
        break;
      default:
        break;
    }
    element.remove();
  }

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

// used to render warning box
Widget _renderWarning(dom.Element element) {
  var content = <TextSpan>[];
  for (var tr in element
      .getElementsByTagName("table")
      .first
      .getElementsByTagName("tbody")
      .first
      .getElementsByTagName("tr")) {
    for (var e in tr.getElementsByTagName("td")) {
      // Get to table data
      content.addAll(
        _renderText(
          e.innerHtml.replaceAll(RegExp(r'<img.+?\/?>'), ""),
        ),
      );
    }
  }
  return Warning(content: content);
}

/// Used to render basic text with bold and italic formatting
List<TextSpan> _renderText(String innerHtml) {
  var unescape = HtmlUnescape();
  innerHtml = unescape.convert(innerHtml);
  var content = <TextSpan>[];
  var input = innerHtml
      .replaceAll(RegExp(r"<(?!(?:\/b)|(?:\/i)|b|i).+?>", dotAll: true), "")
      .replaceAll("\\n", "\r");
  var noFormatting =
      input.split(RegExp(r"(?:<b.*?>.+?<\/b>)|<i.*?>.+?<\/i>", dotAll: true));
  var needToFormat = RegExp(r"(?:<b.*?>.+?<\/b>)|<i.*?>.+?<\/i>", dotAll: true)
      .allMatches(input)
      .toList();
  for (var s in needToFormat) {
    content.add(TextSpan(
        text: noFormatting[needToFormat.indexOf(s)])); // add text before styled
    var raw = s.group(0)!;
    content.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
  }
  content.add(TextSpan(text: noFormatting.last)); // add last
  return content;
}