package com.wasu.cs.widget;

import android.content.Context;
import android.graphics.PointF;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by Danxx on 2016/6/28.
 * 动态计算RecyclerView的宽高，避免在scrollview中recyclerview不显示
 */
public class FocusLinearLayoutManager extends LinearLayoutManager {
    /**
     * Creates a vertical LinearLayoutManager
     *
     * @param context Current context, will be used to access resources.
     */
    public FocusLinearLayoutManager(Context context) {
        super(context);
    }

    public FocusLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

    public FocusLinearLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    private int[] mMeasuredDimension = new int[2];

    @Override
    public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
                          int widthSpec, int heightSpec) {

        final int widthMode = View.MeasureSpec.getMode(widthSpec);
        final int heightMode = View.MeasureSpec.getMode(heightSpec);
        final int widthSize = View.MeasureSpec.getSize(widthSpec);
        final int heightSize = View.MeasureSpec.getSize(heightSpec);

        int width = 0;
        int height = 0;
        for (int i = 0; i < getItemCount(); i++) {
            measureScrapChild(recycler, i,
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    mMeasuredDimension);

            if (getOrientation() == HORIZONTAL) {
                width = width + mMeasuredDimension[0];
                if (i == 0) {
                    height = mMeasuredDimension[1];
                }
            } else {
                height = height + mMeasuredDimension[1];
                if (i == 0) {
                    width = mMeasuredDimension[0];
                }
            }
        }
        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
                width = widthSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:
        }

        switch (heightMode) {
            case View.MeasureSpec.EXACTLY:
                height = heightSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:
        }

        setMeasuredDimension(width, height);
    }

    /**
     * 动态计算RecyclerView的宽高，避免在scrollview中recyclerview不显示
     * @param recycler
     * @param position
     * @param widthSpec
     * @param heightSpec
     * @param measuredDimension
     */
    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                                   int heightSpec, int[] measuredDimension) {
        try {
            View view = recycler.getViewForPosition(0);//fix 动态添加时报IndexOutOfBoundsException

            if (view != null) {
                RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();

                int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                        getPaddingLeft() + getPaddingRight(), p.width);

                int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                        getPaddingTop() + getPaddingBottom(), p.height);

                view.measure(childWidthSpec, childHeightSpec);
                measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
                measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
                recycler.recycleView(view);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
        }
    }

    @Override
    public int computeHorizontalScrollRange(RecyclerView.State state) {
        return super.computeHorizontalScrollRange(state);
    }

    @Override
    public int computeHorizontalScrollExtent(RecyclerView.State state) {
        return super.computeHorizontalScrollExtent(state);
    }

    @Override
    public int computeHorizontalScrollOffset(RecyclerView.State state) {
        return super.computeHorizontalScrollOffset(state);
    }

    @Override
    public PointF computeScrollVectorForPosition(int targetPosition) {
        return super.computeScrollVectorForPosition(targetPosition);
    }
}
