AllowOnlyLettersAndNoConsecutiveSpaces

AllowOnlyLettersAndNoConsecutiveSpaces.kt

fun EditText.allowOnlyLettersAndNoConsecutiveSpaces() {
    filters = arrayOf(InputFilter { enteredText, start, end, dest, dstart, dend ->
        if (enteredText.toString().matches("[a-zA-ZğüşıöçĞÜŞİÖÇ ]*".toRegex())) {

            when {
                //If the first character is entered as empty
                enteredText.isBlank() && dest.isEmpty() -> ""

                //If the entered character is empty and entered as empty at the first index
                enteredText.isBlank() && dend == 0 -> ""

                //If a space is intended to be entered between two letters
                enteredText.isBlank() && dest[dend - 1] != ' ' -> " "

                //If a second space is intended to be entered after the last character.
                enteredText.isBlank() || (enteredText[0] == ' ' && dest[dend - 1] == ' ') -> ""

                //If a second space is intended to be entered between two characters.
                enteredText.last() == ' ' && dest.length != dend -> enteredText.trimEnd()

                else -> {
                    null
                }
            }
        } else {
            null
        }
    })
}