import 'package:flutter/material.dart';
import 'package:html/dom.dart' as dom;
import 'package:html/parser.dart' as parser;

import '../widget/net_image_widget.dart';
import 'html_pro_parser.dart';

class HtmlParser {
  HtmlParser({
    required this.width,
    this.onLinkTap,
    this.imgLinkTap,
    this.renderNewlines = false,
  });

  final double width;
  final Function(String)? onLinkTap;
  final Function(String)? imgLinkTap;
  final bool renderNewlines;

  /// 解析 html 字符串，返回 body 对应的 widget 列表
  List<Widget> parse(String data) {
    if (renderNewlines) {
      data = data.replaceAll("\n", "<br />");
    }
    final document = parser.parse(data);
    return [_parseNode(document.body)];
  }

  Widget _parseNode(dom.Node? node) {
    if (node is dom.Element) {
      switch (node.localName) {
        case "a":
          return GestureDetector(
            onTap: () {
              if (node.attributes.containsKey('href') && onLinkTap != null) {
                String? url = node.attributes['href'] ?? "";
                onLinkTap?.call(url);
              }
            },
            child: DefaultTextStyle.merge(
              child: Wrap(children: _parseNodeList(node.nodes)),
              style: const TextStyle(
                decoration: TextDecoration.underline,
                color: Colors.blueAccent,
                decorationColor: Colors.blueAccent,
              ),
            ),
          );
        case "abbr":
        case "acronym":
          return _styledWrap(
            node,
            const TextStyle(
              decoration: TextDecoration.underline,
              decorationStyle: TextDecorationStyle.dotted,
            ),
          );
        case "address":
        case "cite":
        case "dfn":
        case "em":
        case "i":
        case "var":
          return _styledWrap(node, const TextStyle(fontStyle: FontStyle.italic));
        case "article":
        case "aside":
        case "body":
        case "div":
        case "footer":
        case "header":
        case "main":
        case "nav":
        case "noscript":
        case "section":
          return _widthWrap(node);
        case "b":
        case "strong":
          return _styledWrap(node, const TextStyle(fontWeight: FontWeight.bold));
        case "bdi":
        case "data":
        case "dt":
        case "figcaption":
        case "rp":
        case "rt":
        case "ruby":
        case "time":
          return _wrapList(node);
        case "bdo":
          if (node.attributes["dir"] != null) {
            return Directionality(
              textDirection: node.attributes["dir"] == "rtl" ? TextDirection.rtl : TextDirection.ltr,
              child: Wrap(children: _parseNodeList(node.nodes)),
            );
          }
          //Direction attribute is required, just render the text normally now.
          return _wrapList(node);
        case "big":
          return _styledWrap(node, const TextStyle(fontSize: 20.0));
        case "blockquote":
          return Padding(
            padding: const EdgeInsets.fromLTRB(40.0, 14.0, 40.0, 14.0),
            child: _widthWrap(node),
          );
        case "br":
          if (_isNotFirstBreakTag(node)) {
            return const Text("\n");
          }
          return SizedBox(width: width);
        case "caption":
        case "center":
          return SizedBox(
            width: width,
            child: Wrap(
              alignment: WrapAlignment.center,
              children: _parseNodeList(node.nodes),
            ),
          );
        case "code":
        case "kbd":
        case "samp":
        case "tt":
          return _styledWrap(node, const TextStyle(fontFamily: 'monospace'));
        case "dd":
          return Padding(
            padding: const EdgeInsets.only(left: 40.0),
            child: _widthWrap(node),
          );
        case "del":
        case "s":
        case "strike":
          return _styledWrap(node, const TextStyle(decoration: TextDecoration.lineThrough));
        case "dl":
          return Padding(
            padding: const EdgeInsets.only(top: 14.0, bottom: 14.0),
            child: _columnStartList(node),
          );
        case "figure":
          return Padding(
            padding: const EdgeInsets.fromLTRB(40.0, 14.0, 40.0, 14.0),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.center,
              children: _parseNodeList(node.nodes),
            ),
          );
        case "h1":
          return _heading(node, 28.0);
        case "h2":
          return _heading(node, 21.0);
        case "h3":
          return _heading(node, 16.0);
        case "h4":
          return _heading(node, 14.0);
        case "h5":
          return _heading(node, 12.0);
        case "h6":
          return _heading(node, 10.0);
        case "hr":
          return Padding(
            padding: const EdgeInsets.only(top: 7.0, bottom: 7.0),
            child: Container(
              height: 1,
              decoration: const BoxDecoration(color: Colors.white),
            ),
          );
        case "img":
          final src = node.attributes['src'];
          final alt = node.attributes['alt'];
          if (src != null) {
            // 原代码此处计算的 isMaxWidth 会被无条件覆盖为 true，等价简化为永远 maxFinite
            return GestureDetector(
              onTap: () => imgLinkTap?.call(src),
              child: NetworkImageLoader(
                imageUrl: src,
                fit: BoxFit.contain,
                width: double.maxFinite,
                borderRadius: 0,
                placeHolderWidget: Container(color: Colors.white),
              ),
            );
          } else if (alt != null) {
            //Temp fix for https://github.com/flutter/flutter/issues/736
            if (alt.endsWith(" ")) {
              return Container(padding: const EdgeInsets.only(right: 2.0), child: Text(alt));
            }
            return Text(alt);
          }
          return Container();
        case "ins":
        case "u":
          return _styledWrap(node, const TextStyle(decoration: TextDecoration.underline));
        case "li":
          String type = node.parent?.localName ?? ""; // Parent type; usually ol or ul
          const EdgeInsets markPadding = EdgeInsets.symmetric(horizontal: 4.0);
          Widget mark;
          switch (type) {
            case "ul":
              mark = Container(padding: markPadding, child: Text('•'));
              break;
            case "ol":
              int index = (node.parent?.children.indexOf(node) ?? 0) + 1;
              mark = Container(padding: markPadding, child: Text("$index."));
              break;
            default: //Fallback to middle dot
              mark = const SizedBox.shrink();
              break;
          }
          return SizedBox(
            width: width,
            child: Wrap(
              children: <Widget>[mark, Wrap(children: _parseNodeList(node.nodes))],
            ),
          );
        case "mark":
          return _styledWrap(
            node,
            TextStyle(color: Colors.black, background: _getPaint(Colors.yellow)),
          );
        case "ol":
        case "ul":
        case "table":
        case "tbody":
        case "tfoot":
        case "thead":
          return _columnStartList(node);
        case "p":
          return DefaultTextStyle.merge(
            child: Padding(
              padding: EdgeInsets.only(top: 6.0, bottom: 6.0),
              child: Container(
                alignment: HtmlProParser.alignment(node.attributes["style"]),
                width: width,
                child: Wrap(
                  alignment: HtmlProParser.wrapAlignment(node.attributes["style"]),
                  children: _parseNodeList(node.nodes),
                ),
              ),
            ),
            style: TextStyle(height: HtmlProParser.lineHeight(node.attributes["style"])),
          );
        case "font":
          Color? textColor;
          String colorStr = node.attributes["color"] ?? "";
          if (colorStr.length == 7) {
            textColor = HexColor(colorStr);
          }
          double fontSize = 14;
          try {
            //字体大小和h5那边约定
            Map<String, double> fontSizeMap = {"1": 14, "2": 17, "3": 20, "4": 23, "5": 26, "6": 29, "7": 32};
            if (node.attributes["size"] is String) {
              fontSize = fontSizeMap[node.attributes["size"]] ?? 14;
            }
          } catch (_) {}
          return _styledWrap(
            node,
            TextStyle(
              color: textColor,
              fontSize: fontSize,
              backgroundColor: HtmlProParser.spanBg(node.attributes["style"]),
            ),
          );
        case "pre":
          return Padding(
            padding: const EdgeInsets.all(14.0),
            child: DefaultTextStyle.merge(
              child: Text(node.innerHtml),
              style: const TextStyle(fontFamily: 'monospace'),
            ),
          );
        case "q":
          return DefaultTextStyle.merge(
            child: Wrap(children: [
              const Text("\""),
              ..._parseNodeList(node.nodes),
              const Text("\""),
            ]),
            style: const TextStyle(fontStyle: FontStyle.italic),
          );
        case "small":
          return _styledWrap(node, const TextStyle(fontSize: 10.0));
        case "span":
          return Container(
            color: HtmlProParser.spanBg(node.attributes['style']),
            child: Wrap(children: _parseNodeList(node.nodes)),
          );
        case "td":
          int colspan = 1;
          if (node.attributes['colspan'] != null) {
            colspan = int.tryParse(node.attributes['colspan'] ?? "1") ?? 1;
          }
          return Expanded(
            flex: colspan,
            child: Wrap(children: _parseNodeList(node.nodes)),
          );
        case "template":
          //Not usually displayed in HTML
          return Container();
        case "th":
          int colspan = 1;
          if (node.attributes['colspan'] != null) {
            colspan = int.tryParse(node.attributes['colspan'] ?? "1") ?? 1;
          }
          return DefaultTextStyle.merge(
            child: Expanded(
              flex: colspan,
              child: Wrap(
                alignment: WrapAlignment.center,
                children: _parseNodeList(node.nodes),
              ),
            ),
            style: const TextStyle(fontWeight: FontWeight.bold),
          );
        case "tr":
          return Row(
            crossAxisAlignment: CrossAxisAlignment.center,
            children: _parseNodeList(node.nodes),
          );
      }
    } else if (node is dom.Text) {
      //We don't need to worry about rendering extra whitespace
      if (node.text.trim() == "" && !node.text.contains(" ")) {
        return const Wrap();
      }
      if (node.text.trim() == "" && node.text.contains(" ")) {
        node.text = " ";
      }
      String finalText = trimStringHtml(node.text);
      //Temp fix for https://github.com/flutter/flutter/issues/736
      if (finalText.endsWith(" ")) {
        return Container(padding: EdgeInsets.only(right: 2.0), child: Text(finalText));
      } else {
        return Text(finalText);
      }
    }
    return const Wrap();
  }

  // ========== 私有 helper ==========

  /// `DefaultTextStyle.merge(Wrap(parseNodes), style)` 模式复用
  Widget _styledWrap(dom.Element node, TextStyle style) {
    return DefaultTextStyle.merge(
      child: Wrap(children: _parseNodeList(node.nodes)),
      style: style,
    );
  }

  /// `SizedBox(width: width, child: Wrap(parseNodes))` 模式复用
  Widget _widthWrap(dom.Element node) {
    return SizedBox(
      width: width,
      child: Wrap(children: _parseNodeList(node.nodes)),
    );
  }

  /// 单纯包一层 Wrap
  Widget _wrapList(dom.Element node) {
    return Wrap(children: _parseNodeList(node.nodes));
  }

  /// `Column(crossAxisAlignment: start, children: parseNodes)` 模式复用
  Widget _columnStartList(dom.Element node) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: _parseNodeList(node.nodes),
    );
  }

  /// h1-h6 共用：bold + 指定 fontSize + 全宽 Wrap
  Widget _heading(dom.Element node, double fontSize) {
    return DefaultTextStyle.merge(
      child: SizedBox(
        width: width,
        child: Wrap(children: _parseNodeList(node.nodes)),
      ),
      style: TextStyle(fontSize: fontSize, fontWeight: FontWeight.bold),
    );
  }

  List<Widget> _parseNodeList(List<dom.Node> nodeList) {
    return nodeList.map(_parseNode).toList();
  }

  Paint _getPaint(Color color) => Paint()..color = color;

  String trimStringHtml(String stringToTrim) {
    // 去掉换行，并把连续空格合并为单个空格
    return stringToTrim.replaceAll("\n", "").replaceAll(RegExp(' +'), ' ');
  }

  bool _isNotFirstBreakTag(dom.Node? node) {
    int? index = node?.parentNode?.nodes.indexOf(node);
    if (index == null) return false;
    if (index == 0) {
      if (node?.parentNode == null) {
        return false;
      }
      return _isNotFirstBreakTag(node?.parentNode);
    } else if (node?.parentNode?.nodes[index - 1] is dom.Element) {
      if ((node?.parentNode?.nodes[index - 1] as dom.Element).localName == "br") {
        return true;
      }
      return false;
    } else if (node?.parentNode?.nodes[index - 1] is dom.Text) {
      if ((node?.parentNode?.nodes[index - 1] as dom.Text).text.trim() == "") {
        return _isNotFirstBreakTag(node?.parentNode?.nodes[index - 1]);
      } else {
        return false;
      }
    }
    return false;
  }
}