BottomSpaceDecoration for RecyclerView item

BottomSpaceDecoration.txt

import android.graphics.Rect
import android.view.View
import androidx.recyclerview.widget.RecyclerView

// ViewHolder of current item, index of item, itemsCount
typealias SpacePredictor = (RecyclerView.ViewHolder, Int, Int) -> Boolean

class BottomSpaceToTopItemDecoration(
    val predictor: SpacePredictor
)  : RecyclerView.ItemDecoration() {

    private var spaceToAddForLastItem: Int? = null

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        val adapter = parent.adapter ?: return
        val childPosition = parent.getChildLayoutPosition(view)
        val viewHolder = parent.getChildViewHolder(view)
        val needActions = predictor(viewHolder, childPosition, adapter.itemCount)
        if (needActions && spaceToAddForLastItem == null) {
            // need to add space to lastView
            val lastViewBottom = parent.findViewHolderForAdapterPosition(adapter.itemCount - 1)?.itemView?.bottom ?: -1
            spaceToAddForLastItem = if (lastViewBottom == -1) {
                0
            } else {
                parent.height - view.height - (lastViewBottom - view.bottom)
            }
        }
        if (childPosition == adapter.itemCount - 1) {
            spaceToAddForLastItem?.let {
                outRect.bottom = it
            }
        }
    }

}