package com.hjq.widget;

import android.content.Context;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

/**
 *    desc   : 简单的 Layout（常用于自定义组合控件继承的基类，可以起到性能优化的作用）
 */
public class SimpleLayout extends ViewGroup {

    public SimpleLayout(Context context) {
        super(context);
    }

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

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

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    public SimpleLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int maxHeight = 0;
        int maxWidth = 0;
        int childState = 0;

        // 测量子 View
        for (int i = 0; i < getChildCount(); i++) {
            final View child = getChildAt(i);
            // 被测量的子 View 不能是隐藏的
            if (child.getVisibility() != GONE) {
                measureChildWithMargins(child, widthMeasureSpec, 0, heightMeasureSpec, 0);
                final MarginLayoutParams params = (MarginLayoutParams) child.getLayoutParams();
                maxWidth = Math.max(maxWidth, child.getMeasuredWidth() + params.leftMargin + params.rightMargin);
                maxHeight = Math.max(maxHeight, child.getMeasuredHeight() + params.topMargin + params.bottomMargin);
                childState = combineMeasuredStates(childState, child.getMeasuredState());
            }
        }

        maxWidth += getPaddingLeft() + getPaddingRight();
        maxHeight += getPaddingTop() + getPaddingBottom();

        maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());
        maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());

        // 测量自身
        setMeasuredDimension(resolveSizeAndState(maxWidth, widthMeasureSpec, childState),
                resolveSizeAndState(maxHeight, heightMeasureSpec,
                        childState << MEASURED_HEIGHT_STATE_SHIFT));
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        // 遍历子 View
        for (int i = 0; i < getChildCount(); i++) {
            final View child = getChildAt(i);
            final MarginLayoutParams params = (MarginLayoutParams) child.getLayoutParams();
            // 将子 View 放置到左上角的位置
            child.layout(getPaddingLeft() + params.leftMargin,
                    getPaddingTop() + params.topMargin,
                    getPaddingRight() + child.getMeasuredWidth() + params.rightMargin,
                    getPaddingBottom() + child.getMeasuredHeight() + params.bottomMargin);
        }
    }

    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new MarginLayoutParams(getContext(), attrs);
    }

    @Override
    protected LayoutParams generateDefaultLayoutParams() {
        return new MarginLayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
    }

    @Override
    protected LayoutParams generateLayoutParams(LayoutParams p) {
        return new MarginLayoutParams(p);
    }
}