OnKeyPress.kt

private fun onKeyPress(key: Keypad) {
        when(key) {
            Keypad.KeyDelete -> {
                /* when delete key is clicked */
                if (timeState.value.isDataEmpty())
                    return
                deleteTime()
            }
            Keypad.Key00 -> {
                /* when double zero key is clicked */
                if (timeState.value.isDataEmpty()
                    || timeState.value.isHoursHalfFull()
                    || timeState.value.isDataFull()
                )
                    return
                addTime(Keypad.Key0.value)
                addTime(Keypad.Key0.value)
            }
            Keypad.Key0 -> {
                /* when zero key is clicked */
                if (timeState.value.isDataEmpty()
                    || timeState.value.isDataFull()
                )
                    return
                addTime(key.value)
            }
            else -> {
                /* when any num key is clicked */
                if (timeState.value.isDataFull())
                    return
                addTime(key.value)
            }
        }
    }