TextWatchers.kt

package ir.dariacard

import android.text.Editable
import android.text.TextUtils
import android.text.TextWatcher
import androidx.annotation.NonNull
import androidx.appcompat.widget.AppCompatEditText
import java.lang.Exception
import java.text.NumberFormat

/*
    how to use:
    edtCard?.addTextChangedListener(SerialCardTextWatcher(edtCard))
 */

abstract class BaseTextWatcher : TextWatcher {

    var beforeText: String = ""

    override fun afterTextChanged(s: Editable?) {}

    override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
        beforeText = s.toString()
    }

    abstract fun format(@NonNull amount: String): String

    protected fun removeNonNumeric(@NonNull numberString: String): String {
        var numbers = ""
        for (i in numberString) {
            if (i.isDigit())
                numbers += i
        }
        return numbers
    }

    protected fun getNewCursorPosition(digitCountToRightOfCursor: Int, numberString: String): Int {
        var position = 0
        var c = digitCountToRightOfCursor
        for (i in numberString.reversed()) {
            if (c == 0)
                break
            if (i.isDigit())
                c--
            position++
        }
        return numberString.length - position
    }

    protected fun getNumberOfDigits(@NonNull text: String): Int {
        var count = 0
        for (i in text)
            if (i.isDigit())
                count++
        return count
    }

}

class SerialCardTextWatcher(private val editText: AppCompatEditText) : BaseTextWatcher() {

    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
        if (s == null) return
        // 1. get cursor position : p0 = start + before
        val initialCursorPosition = start + before
        //2. get digit count after cursor position : c0
        val numOfDigitsToRightOfCursor = getNumberOfDigits(
            beforeText.substring(initialCursorPosition, beforeText.length)
        )
        val newAmount = format(s.toString())
        editText.removeTextChangedListener(this)
        editText.setText(newAmount)
        //set new cursor position
        try {
            editText.setSelection(getNewCursorPosition(numOfDigitsToRightOfCursor, newAmount))
        } catch (e: Exception) {
            e.printStackTrace()
        }
        editText.addTextChangedListener(this)
    }

    override fun format(amount: String): String {
        val result = removeNonNumeric(amount)
        val amt = if (!TextUtils.isEmpty(result) && TextUtils.isDigitsOnly(result)) result else ""
        var res = ""
        for (i in amt.indices) {
            if (i != 0 && i % 4 == 0)
                res += " - "
            res += amt[i]
        }
        return res
    }

}



class CostTextWatcher(private val editText: AppCompatEditText) : BaseTextWatcher() {

    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
        if (s == null) return
        // 1. get cursor position : p0 = start + before
        val initialCursorPosition = start + before
        //2. get digit count after cursor position : c0
        val numOfDigitsToRightOfCursor = getNumberOfDigits(
            beforeText.substring(initialCursorPosition, beforeText.length)
        )
        val newAmount = format(s.toString())
        editText.removeTextChangedListener(this)
        editText.setText(newAmount)
        //set new cursor position
        try {
            editText.setSelection(getNewCursorPosition(numOfDigitsToRightOfCursor, newAmount))
        } catch (e: Exception) {
            e.printStackTrace()
        }
        editText.addTextChangedListener(this)
    }

    override fun format(amount: String): String {
        val result = removeNonNumeric(amount)
        var amt: Long? = if (!TextUtils.isEmpty(result) && TextUtils.isDigitsOnly(result)) result.toLongOrNull() else 0
        if (amt == null) {
            amt = result.substring(0, 15).toLong()
        }
        val formatter = NumberFormat.getNumberInstance()
        //return formatter.format(amt).plus(" ﷼")
        //return "﷼ ".plus(formatter.format(amt))
        return formatter.format(amt)
    }

}



class PostalCodeTextWatcher(private val editText: AppCompatEditText) : BaseTextWatcher() {

    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
        if (s == null) return
        // 1. get cursor position : p0 = start + before
        val initialCursorPosition = start + before
        //2. get digit count after cursor position : c0
        val numOfDigitsToRightOfCursor = getNumberOfDigits(
            beforeText.substring(initialCursorPosition, beforeText.length)
        )
        val newAmount = format(s.toString())
        editText.removeTextChangedListener(this)
        editText.setText(newAmount)
        //set new cursor position
        try {
            editText.setSelection(getNewCursorPosition(numOfDigitsToRightOfCursor, newAmount))
        } catch (e: Exception) {
            e.printStackTrace()
        }
        editText.addTextChangedListener(this)
    }

    override fun format(amount: String): String {
        val result = removeNonNumeric(amount)
        val amt = if (!TextUtils.isEmpty(result) && TextUtils.isDigitsOnly(result)) result else ""
        var res = ""
        for (i in amt.indices) {
            if (i != 0 && i % 5 == 0)
                res += "-"
            res += amt[i]
        }
        return res
    }

}