Parse a markdown and divide it into sections

markdown_parser.dart

import 'package:markdown/markdown.dart';
import 'dart:io' as io;

final _structuralHeaderTags = ['h1', 'h2', 'h3', 'h4', 'h5', 'h6'];

class Section {
  int level;
  Node titleNode;
  List<Node> contentNodes;
  List<Section> children;
  Section parent;

  void addContentNodes(Node nodes) {
    contentNodes = List.from(contentNodes)..add(nodes);
  }

  Section({level, titleNode}) {
    this.level = level;
    this.titleNode = titleNode;
    contentNodes = [];
    children = [];
  }
}

void parser(List<Node> nodes) {
  var finalSectionList = <Section>[];
  Section currentSection;

  for (final node in nodes) {
    final nodeTag = node is Element ? node.tag : null;

    final isHeading =
        nodeTag != null && _structuralHeaderTags.contains(nodeTag);

    var section = Section(titleNode: node);
    if (isHeading) {
      section.level = _structuralHeaderTags.indexOf(nodeTag);
    }
    if (currentSection == null) {
      currentSection = section;
      finalSectionList.add(section);
      continue;
    }

    if (isHeading) {
      final currentLevel = _structuralHeaderTags.indexOf(nodeTag);
      var previousLevel = currentSection.level;

      if (currentLevel > previousLevel) {
        currentSection.children.add(section);
        section.parent = currentSection;
        currentSection = section;
        continue;
      } else if (currentLevel < previousLevel) {
        while (currentLevel < previousLevel) {
          currentSection = currentSection.parent;
          previousLevel = currentSection.level;
        }
        if (currentSection.parent != null) {
          currentSection = currentSection.parent;
          section.parent = currentSection;
          currentSection.children.add(section);
          currentSection = section;
        } else {
          finalSectionList.add(section);
          currentSection = section;
        }
      } else {
        if (currentSection.parent != null) {
          currentSection = currentSection.parent;
          section.parent = currentSection;
          currentSection.children.add(section);
          currentSection = section;
        } else {
          finalSectionList.add(section);
          currentSection = section;
        }
      }
    } else {
      currentSection.contentNodes.add(node);
    }
  }

  printEverything(finalSectionList);
}

void printEverything(List<Section> sections) {
  sections.forEach((element) {
    print(element.level);
    print(element.titleNode.textContent);
    print('--------content nodes----------');
    element.contentNodes.forEach((e) {
      print(e.textContent);
    });

    print('--------children----------');
    printEverything(element.children);
    print('--------end----------');
  });
}

void main(List<String> args) {
  final pwd = io.Directory.current.path;
  final nodes = getNodes(pwd + '/bin/readme2.md');
  parser(nodes);
}

List<Node> getNodes(String filePath) {
  var file = io.File(filePath);
  var document = Document();
  var markdown = file.readAsStringSync();
  var lines = markdown.replaceAll('\r\n', '\n').split('\n');
  return document.parseLines(lines);
}