IBAN Code kotlin simplified version

editText_IBAN_mask.kt

package com.example.test

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.text.Editable
import android.text.TextWatcher
import androidx.core.text.set
import com.example.test.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        setUI()
    }

    private fun setUI() {

        binding.editTextTest.addTextChangedListener(object : TextWatcher {

            var _ignore = false
            var _deletion = false
            override fun afterTextChanged(s: Editable) {

                if (_ignore)
                    return

                _ignore = true

                val space = ' '

                if (!_deletion) {

                    while (true) {

                        s.forEachIndexed { index, c ->
                            if (c == space) {
                                s.replace(index, index + 1, "")
                            }
                        }

                        s.forEachIndexed { index, c ->

                            if (index >= 3 && s[index] != ' ' && s[index - 1] != ' ' && s[index - 2] != ' ' && s[index - 3] != ' ') {
                                s.insert(index + 1, " ")
                            }

                        }

                        break

                    }

                }

                _ignore = false

            }

            override fun beforeTextChanged(
                s: CharSequence, start: Int,
                count: Int, after: Int
            ) {
                _deletion = after < count
            }

            override fun onTextChanged(
                s: CharSequence, start: Int,
                before: Int, count: Int
            ) {
            }
        })

    }


}