package com.xscm.moduleutil.widget;

import android.view.View;

import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

public class InfintLinearLayoutManager extends LinearLayoutManager {
    public InfintLinearLayoutManager(RecyclerView recyclerView) {
        super(recyclerView.getContext(), HORIZONTAL, false);
    }

    @Override
    public boolean canScrollHorizontally() {
        return true; // 允许水平滑动
    }

    @Override
    public int scrollVerticallyBy(int dy, RecyclerView.Recycler recycler, RecyclerView.State state) {
        return super.scrollVerticallyBy(dy, recycler, state);
    }

    @Override
    public int scrollHorizontallyBy(int dx, RecyclerView.Recycler recycler, RecyclerView.State state) {
        // 获取最后一个和第一个可见 item 的位置
        int first = findFirstVisibleItemPosition();
        int last = findLastVisibleItemPosition();

        if (first == 0 && dx > 0) {
            // 滑动到了最左边，现在往右滑，把最后一个 item 移动到前面复用
            View lastView = getChildAt(last);
            if (lastView != null) {
                layoutScrapView(lastView, last, -1);
                offsetChildrenHorizontal(-getDecoratedMeasuredWidth(lastView));
                return dx;
            }
        } else if (last == getItemCount() - 1 && dx < 0) {
            // 滑动到了最右边，现在往左滑，把第一个 item 移动到最后面复用
            View firstView = getChildAt(first);
            if (firstView != null) {
                layoutScrapView(firstView, first, +1);
                offsetChildrenHorizontal(+getDecoratedMeasuredWidth(firstView));
                return dx;
            }
        }

        return super.scrollHorizontallyBy(dx, recycler, state);
    }

    private void layoutScrapView(View view, int position, int direction) {
        removeView(view);

        // 复用的 item 设置为新的位置
        int newPosition = direction > 0 ? getItemCount() - 1 : 0;
        addView(view, direction > 0 ? getChildCount() : 0);

        // 更新 adapter 的 position
        RecyclerView.LayoutParams lp = (RecyclerView.LayoutParams) view.getLayoutParams();
        layoutDecoratedWithMargins(view,
                0,
                0,
                getDecoratedMeasuredWidth(view),
                getDecoratedMeasuredHeight(view));
    }
}