// blog: https://kawa.dev
// github: https://github.com/kawa1214 

import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      home: MyWidget(),
    ),
  );
}

TextStyle textStyle(String text) {
  String _textTag = text.split(" ").first;

  TextStyle _h1 = TextStyle(color: Colors.black, fontSize: 32);
  TextStyle _h2 = TextStyle(color: Colors.black, fontSize: 26);
  TextStyle _p = TextStyle(color: Colors.black, fontSize: 16); 
 
 switch (_textTag) {
   case "#":
     return _h1;
     break;
    case "##":
      return _h2;
      break;
   default:
    return _p;
 }
}

class CustomTextEditingController extends TextEditingController {
  CustomTextEditingController({String text}) : super(text: text);

  @override
  TextSpan buildTextSpan({TextStyle style, bool withComposing}) {
    List _splitTextList = text.split("\n");

    return TextSpan(
        children: <TextSpan>[
          for (String item in _splitTextList) 
            TextSpan(
              text: item + "\n",
              style: textStyle(item),
            ),
        ]
      );
   }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    TextEditingController _textEditingController = CustomTextEditingController();
    return Scaffold(
      body: Center(
        child: Padding(
          padding: EdgeInsets.all(100.0),
            child: TextField(
              enabled: true,
              keyboardType: TextInputType.multiline,
              minLines: null,
              maxLines: 20,
              autocorrect: false,
              showCursor: false,
              decoration: InputDecoration(
                hintMaxLines: null,
                border: InputBorder.none,
                hintStyle: TextStyle(fontSize: 20.0, color: Colors.grey),
                hintText: "Input Markdown Text \nexample) # h1 ## h2 notTag",
              ),
              obscureText: false,
              controller: _textEditingController,
            ),
        ),
      ),
    );
  }
}