CodeVerificationUiUtil

import android.view.KeyEvent
import android.view.View
import android.widget.EditText
import com.google.android.material.textfield.TextInputEditText
import com.justika.client.extention.addOnTextChangedListener

class CodeVerificationUiUtil(private val editTexts: List<EditText>) {

    private lateinit var currentEditText: EditText

    /**
     * Listen edit texts on changed
     */
    var codeVerificationUiListener: CodeVerificationUiListener? = null

    /**
     * Start bind given editTexts
     * Should be called on onCreate
     */
    fun bind(){
        editTexts.forEach {
            it.setOnFocusChangeListener(this::onOtpFieldFocusChanged)
            it.addOnTextChangedListener(onTextChanged = this::onMfaCodeFieldTextChanged)
            it.setOnKeyListener(this::onOtpBackSpaced)
        }
    }

    private fun onOtpFieldFocusChanged(view: View, hasFocus: Boolean) {
        if (!hasFocus) return

        editTexts
            .firstOrNull {
                it.text?.isEmpty() == true
            }?.requestFocus() ?: editTexts.last().requestFocus()

        currentEditText = view as TextInputEditText
    }

    private fun onMfaCodeFieldTextChanged(text: String) {
        onOtpFieldFocusChanged(currentEditText, true)
        formFillCheck()
    }

    private fun onOtpBackSpaced(v: View?, keyCode: Int, event: KeyEvent?): Boolean {
        //You can identify which key pressed buy checking keyCode value with KeyEvent.KEYCODE_
        if (keyCode == KeyEvent.KEYCODE_DEL && event?.action == KeyEvent.ACTION_DOWN) {
            //this is for backspace
            editTexts
                .lastOrNull {
                    it.text?.isEmpty() == false
                }?.let {
                    it.setText("")
                    it.requestFocus()
                }
            return true
        }
        return false
    }

    fun getCode() =
        editTexts.joinToString(separator = "") { it.text.toString() }

    private fun formFillCheck() {
        val isAllFieldsFilled = editTexts.none {
            it.text?.isEmpty() == true
        }

        codeVerificationUiListener?.onCodeChanged(getCode(), isAllFieldsFilled)
    }

    interface CodeVerificationUiListener {
        /**
         * @param code Typed code
         * @param isFilled indicate is all edit texts filled or not,
         * true if filled, false otherwise
         */
        fun onCodeChanged(code: String, isFilled: Boolean)
    }
}