content: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.
   */
  package org.apache.weex.ui.component.helper;
  
  import android.os.Handler;
  import android.os.Looper;
  
  import org.apache.weex.common.Constants;
  import org.apache.weex.common.OnWXScrollListener;
  import org.apache.weex.ui.component.WXComponent;
  import org.apache.weex.ui.component.WXScroller;
  import org.apache.weex.ui.component.list.BasicListComponent;
  import org.apache.weex.ui.component.list.ListComponentView;
  import org.apache.weex.ui.component.list.template.WXRecyclerTemplateList;
  import org.apache.weex.utils.WXUtils;
  
  import java.util.Map;
  
  
  /**
   * Created by furture on 2017/11/13.
   */
  
  public class ScrollStartEndHelper implements Runnable{
  
      private Handler handler;
      private WXComponent component;
      private boolean  hasStart;
      private boolean  canStart = false;
  
      private long  minInterval;
      private int oldState = OnWXScrollListener.IDLE;
  
      private int x;
      private int y;
      private boolean hasScrollEnd;
  
  
      public ScrollStartEndHelper(WXComponent component) {
          this.component = component;
          this.handler = new Handler(Looper.getMainLooper());
          this.minInterval = WXUtils.getNumberInt(component.getAttrs().get("minscrolldelayinterval"), 32);
      }
  
      /**
       * @param  x scroll offset or dx, which is not accurate
       * @param  y scroll offset or dy, which is not accurate
       * */
      public void  onScrolled(int x, int y){
          if((component.getEvents().contains(Constants.Event.SCROLL_START)
                  || component.getEvents().contains(Constants.Event.SCROLL_END))){
              this.x = x;
              this.y = y;
              if(!hasStart && canStart){
                  if(component.getEvents().contains(Constants.Event.SCROLL_START)){
                      Map<String, Object> event = getScrollEvent(x,y);
                      if (null !=event && !event.isEmpty()){
                          component.fireEvent(Constants.Event.SCROLL_START,event);
  
                      }
                  }
                  hasStart = true;
                  canStart = false;
              }
              handler.removeCallbacks(this);
              handler.postDelayed(this, minInterval);
          }
      }
  
  
      @Override
      public void run() {
          if(component.isDestoryed()){
              return;
          }
          if(!hasScrollEnd){
              return;
          }
          if(canStart){
              component.fireEvent(Constants.Event.SCROLL_START, getScrollEvent(this.x, this.y));
              canStart = false;
          }
          if(component.getEvents().contains(Constants.Event.SCROLL_END)){
              component.fireEvent(Constants.Event.SCROLL_END, getScrollEvent(this.x, this.y));
  
          }
          hasStart = false;
          hasScrollEnd = false;
  
      }
  
      private Map<String, Object> getScrollEvent(int offsetX, int offsetY){
          if(component instanceof BasicListComponent){
              BasicListComponent basicListComponent = (BasicListComponent) component;
              if(basicListComponent.getHostView() instanceof ListComponentView){
                  ListComponentView componentView = (ListComponentView) basicListComponent.getHostView();
                  if(componentView != null){
                      return basicListComponent.getScrollEvent(componentView.getInnerView(), offsetX, offsetY);
                  }
              }
          }else if(component instanceof WXRecyclerTemplateList){
              WXRecyclerTemplateList templateList = (WXRecyclerTemplateList) component;
              return templateList.getScrollEvent(templateList.getHostView().getInnerView(), offsetX, offsetY);
          }else if(component instanceof WXScroller){
              WXScroller scroller = (WXScroller) component;
              return scroller.getScrollEvent(offsetX, offsetY);
          }
          return null;
      }
  
      public void onScrollStateChanged(int newState){
  
          if(oldState == OnWXScrollListener.IDLE){
              canStart = true;
          }
  
          if(newState == OnWXScrollListener.IDLE){
              hasScrollEnd = true;
              handler.removeCallbacks(this);
              handler.postDelayed(this, minInterval);
          }
  
          oldState = newState;
      }
  
  
      public static boolean isScrollEvent(String type){
          if(Constants.Event.SCROLL.equals(type)){
              return  true;
          }else if(Constants.Event.SCROLL_START.equals(type)){
              return  true;
          }else if(Constants.Event.SCROLL_END.equals(type)){
              return  true;
          }
          return  false;
      }
  }
  