[Flutter] How to implement numbering list feature in textfield like whatsApp with dart code in...

I'm trying to implement numbering list feature to my app like whatsApp does. It almost got implemented but I found 3 bugs in my code.

Note : I'm not using any outside packages for it, created custom TextEditingController to achieve this.

1. 
   BUG1
   
   
2. 
   BUG2
   
   
3. 
   BUG3
   

Code:

class TestingPage extends StatefulWidget {
const TestingPage({super.key});

@override
State<TestingPage> createState() => _TestingPageState();
}

class _TestingPageState extends State<TestingPage> {
CustomTextEditingController controller = CustomTextEditingController();
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text("Testing"),
centerTitle: true,
),
body: Center(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 30),
child: TextField(
controller: controller,
maxLines: 8,
decoration: const InputDecoration(
hintText: "Enter text here...", border: OutlineInputBorder()),
),
),
),
);
}
}




Custom TextEditingController class :

import 'package:flutter/cupertino.dart';

class CustomTextEditingController extends TextEditingController {
bool isBackPressed = false;
String _previousText = '';

CustomTextEditingController({String text = ''}) : super(text: text) {
addListener(_onTextChanged);
}

// Custom function to handle text changes
void _onTextChanged() {
String text = this.text;
int cursorPosition = selection.baseOffset;

if (_previousText.length > text.length) {
isBackPressed = true;
} else {
isBackPressed = false;
}
_previousText = text;

if (cursorPosition > 0) {
// Detect Enter key press
if (text[cursorPosition - 1] == '\n' && !isBackPressed) {
debugPrint("inside12");
String previousLine = _getPreviousLine(text, cursorPosition);
RegExp numberRegex = RegExp(r'^(\d+)\.\s');

Match? match = numberRegex.firstMatch(previousLine);
if (match != null) {
int currentNumber = int.parse(match.group(1)!);
String newText = text.replaceRange(
cursorPosition,
cursorPosition,
'${currentNumber + 1}. ',
);

value = TextEditingValue(
text: newText,
selection: TextSelection.collapsed(
offset: cursorPosition + currentNumber.toString().length + 2,
),
);
}
}
// Handle backspace to clear line numbering
if (text[cursorPosition - 1] == '\n' &&
cursorPosition > 1 &&
text.substring(cursorPosition - 4, cursorPosition - 1) == '. ') {
debugPrint("inside11");
String newText = text.substring(0, cursorPosition - 4) +
text.substring(cursorPosition);
value = TextEditingValue(
text: newText,
selection: TextSelection.collapsed(offset: cursorPosition - 4),
);
}
}
}

@override
void dispose() {
// Clean up the listener when the controller is disposed
removeListener(_onTextChanged);
super.dispose();
}

String _getPreviousLine(String text, int cursorPosition) {
int lastNewline = text.lastIndexOf('\n', cursorPosition - 2);
if (lastNewline == -1) {
return text.substring(0, cursorPosition).trim();
} else {
return text.substring(lastNewline + 1, cursorPosition - 1).trim();
}
}
}

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