package com.wasu.cs.widget;

import android.content.Context;
import android.graphics.Rect;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;

public class CenterRecyclerView extends RecyclerView {
    private Context mContext;

    public CenterRecyclerView(Context context) {
        super(context);
        init(context);
    }

    public CenterRecyclerView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public CenterRecyclerView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    private void init(Context context) {
        this.mContext = context;
    }

    /*@Override
    public void smoothScrollBy(int dx, int dy) {
        if (hasFocus()) {
            if (dx > 0) {
                int mdx = (int) (dx +mContext.getResources().getDimension(R.dimen.d_10dp));
                super.smoothScrollBy(mdx, dy);
            } else if (dx < 0) {
                int mdx = (int) (dx - mContext.getResources().getDimension(R.dimen.d_10dp));
                super.smoothScrollBy(mdx, dy);
            } else {
                Log.d("danxx", "FRV dy--->" + dx);
            }
        }
//        super.smoothScrollBy(dx ,dy);
    }*/

/**
 * center scroll
 * @param child
 * @param rect
 * @param immediate
 * @return
 */
    @Override
    public boolean requestChildRectangleOnScreen(View child, Rect rect, boolean immediate) {
        final int parentLeft = getPaddingLeft();
        final int parentTop = getPaddingTop();
        final int parentRight = getWidth() - getPaddingRight();
        final int parentBottom = getHeight() - getPaddingBottom();
        final int childLeft = child.getLeft() + rect.left;
        final int childTop = child.getTop()-child.getPaddingTop() + rect.top;
        final int childRight = childLeft + rect.width();
        final int childBottom = childTop + rect.height();

        final int offScreenLeft = Math.min(0, childLeft - parentLeft);
        final int offScreenTop = Math.min(0, childTop - parentTop);
        final int offScreenRight = Math.max(0, childRight - parentRight);
        final int offScreenBottom = Math.max(0, childBottom - parentBottom);

        int centerTop = getHeight() / 2 - child.getHeight() / 2;
        int centerBottom = getHeight() / 2 + child.getHeight() / 2;
        int centerLeft = getWidth() / 2 - child.getWidth() / 2;
        int centerRight = getWidth() / 2 + child.getWidth() / 2;

        int position = getChildAdapterPosition(child);
        int childCount = getAdapter().getItemCount();

        int dx = 0;
        if (position == 0 || position == childCount - 1){
            // Favor the "start" layout direction over the end when bringing one side or the other
            // of a large rect into view. If we decide to bring in end because start is already
            // visible, limit the scroll such that start won't go out of bounds.
            if (ViewCompat.getLayoutDirection(this) == ViewCompat.LAYOUT_DIRECTION_RTL) {
                dx = offScreenRight != 0 ? offScreenRight
                        : Math.max(offScreenLeft, childRight - parentRight);
            } else {
                dx = offScreenLeft != 0 ? offScreenLeft
                        : Math.min(childLeft - parentLeft, offScreenRight);
            }
        }else {
            switch (Gravity.CENTER_HORIZONTAL){
                case Gravity.CENTER_HORIZONTAL:
                case Gravity.CENTER:
                    dx = childLeft - centerLeft;
                    break;
                case Gravity.LEFT:
                    dx = childLeft - parentLeft;
                    break;
            }
        }

        int dy = 0;
        if (position == 0 || position == childCount - 1){
            // Favor bringing the top into view over the bottom. If top is already visible and
            // we should scroll to make bottom visible, make sure top does not go out of bounds.
            dy = offScreenTop != 0 ? offScreenTop
                    : Math.min(childTop - parentTop, offScreenBottom);
        }else {
            switch (Gravity.CENTER_VERTICAL){
                case Gravity.CENTER_VERTICAL:
                case Gravity.CENTER:
                    dy = childTop - centerTop;
                    break;
            }
        }

        if (dx != 0 || dy != 0) {
            if (immediate) {
                scrollBy(dx, dy);
            } else {
                smoothScrollBy(dx, dy);
            }
            return true;
        }
        return false;
    }
}