viewmodel

data class BackDropData(
    val number: Int,
    val axisX: Int = 0,
    var axisY: Int = 0,
)


class BackgroundAnimationViewModel: ViewModel() {
    private var item: Int = 0
    private var _list = MutableStateFlow(emptyList<BackDropData>().toMutableList())
    var list: StateFlow<List<BackDropData>> = _list.asStateFlow()


    fun addNewItem() {
        _list.update {cur ->
            cur.toMutableList().also {
                it.add(BackDropData(item++, axisX =  (0..350).random()))
            }
        }
    }
    private fun deleteItem(item: BackDropData) {
            _list.update {cur ->
                cur.toMutableList().also {
                    it.remove(item)
                }
            }
    }
    fun fallingAnimation(item: BackDropData, limit: Int){
        viewModelScope.launch{
            while (item.axisY < limit) {
                delay(1)
                _list.updateAndGet { cur ->
                    cur.toMutableList().also {
                        it[it.indexOf(item)].axisY++
                    }
                }
            }
            deleteItem(item)
        }
    }
}