/*
 * Copyright 2018 GcsSloop
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Last modified 2018-04-09 23:56:59
 *
 * GitHub: https://github.com/GcsSloop
 * WeiBo: http://weibo.com/GcsSloop
 * WebSite: http://www.gcssloop.com
 */

package com.gcssloop.widget;

import static com.gcssloop.widget.PagerConfig.Logi;

import android.util.DisplayMetrics;
import android.view.View;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.LinearSmoothScroller;
import androidx.recyclerview.widget.RecyclerView;

/**
 * 作用：用于处理平滑滚动
 * 作者：GcsSloop
 * 摘要：用于用户手指抬起后页面对齐或者 Fling 事件。
 */
public class PagerGridSmoothScroller extends LinearSmoothScroller {
    private final RecyclerView mRecyclerView;

    public PagerGridSmoothScroller(@NonNull RecyclerView recyclerView) {
        super(recyclerView.getContext());
        mRecyclerView = recyclerView;
    }

    @Override
    protected void onTargetFound(View targetView, RecyclerView.State state, Action action) {
        RecyclerView.LayoutManager manager = mRecyclerView.getLayoutManager();
        if (null == manager) return;
        if (manager instanceof PagerGridLayoutManager) {
            PagerGridLayoutManager layoutManager = (PagerGridLayoutManager) manager;
            int pos = mRecyclerView.getChildAdapterPosition(targetView);
            int[] snapDistances = layoutManager.getSnapOffset(pos);
            final int dx = snapDistances[0];
            final int dy = snapDistances[1];
            Logi("dx = " + dx);
            Logi("dy = " + dy);
            final int time = calculateTimeForScrolling(Math.max(Math.abs(dx), Math.abs(dy)));
            if (time > 0) {
                action.update(dx, dy, time, mDecelerateInterpolator);
            }
        }
    }

    @Override
    protected float calculateSpeedPerPixel(DisplayMetrics displayMetrics) {
        return PagerConfig.getMillisecondsPreInch() / displayMetrics.densityDpi;
    }
}
