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.list;
  
  import android.support.annotation.NonNull;
  import android.support.annotation.Nullable;
  import android.support.v7.widget.RecyclerView;
  import android.support.v7.widget.helper.ItemTouchHelper;
  
  import org.apache.weex.WXEnvironment;
  import org.apache.weex.ui.component.WXComponent;
  import org.apache.weex.utils.WXLogUtils;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  /**
   * Description:
   * Drag-drop support for list
   * <p>
   * Created by rowandjj(chuyi)<br/>
   */
  
  class DefaultDragHelper implements DragHelper {
  
      private boolean mLongPressEnabled;
  
      @NonNull
      private final EventTrigger mEventTrigger;
      @NonNull
      private final RecyclerView mRecyclerView;
      @NonNull
      private final List<WXComponent> mDataSource;
      @NonNull
      private ItemTouchHelper mItemTouchHelper;
  
      private static final String EVENT_START_DRAG = "dragstart";
      private static final String EVENT_END_DRAG = "dragend";
  
      private static final String TAG_EXCLUDED = "drag_excluded";
  
      private static final String TAG = "WXListExComponent";
  
      private boolean isDraggable = false;
  
      DefaultDragHelper(@NonNull List<WXComponent> dataSource, @NonNull RecyclerView recyclerView, @NonNull EventTrigger trigger) {
          this.mDataSource = dataSource;
          this.mEventTrigger = trigger;
          this.mRecyclerView = recyclerView;
  
          //attach
          this.mItemTouchHelper = new ItemTouchHelper(new DragSupportCallback(this, true));
          try {
              mItemTouchHelper.attachToRecyclerView(mRecyclerView);
          }catch (Throwable e) {
              //ignore
          }
      }
  
      @Override
      public void onDragStart(@NonNull WXComponent component, int from) {
          if (WXEnvironment.isApkDebugable()) {
              WXLogUtils.d(TAG, "list on drag start : from index " + from);
          }
          mEventTrigger.triggerEvent(EVENT_START_DRAG, buildEvent(component.getRef(), from, -1));
      }
  
      @Override
      public void onDragEnd(@NonNull WXComponent component, int from, int to) {
          if (WXEnvironment.isApkDebugable()) {
              WXLogUtils.d(TAG, "list on drag end : " + "from index " + from + " to index " + to);
          }
          mEventTrigger.triggerEvent(EVENT_END_DRAG, buildEvent(component.getRef(), from, to));
      }
  
      @Override
      public void onDragging(int fromPos, int toPos) {
          if (WXEnvironment.isApkDebugable()) {
              WXLogUtils.d(TAG, "list on dragging : from index " + fromPos + " to index " + toPos);
          }
  
          RecyclerView.Adapter adapter = mRecyclerView.getAdapter();
          if (adapter == null) {
              WXLogUtils.e(TAG, "drag failed because of RecyclerView#Adapter is not bound");
              return;
          }
  
          if (fromPos >= 0 && fromPos <= mDataSource.size() - 1 && toPos >= 0 && toPos <= mDataSource.size() - 1) {
              Collections.swap(mDataSource, fromPos, toPos);
              adapter.notifyItemMoved(fromPos, toPos);
          }
      }
  
      @Override
      public boolean isLongPressDragEnabled() {
          return mLongPressEnabled;
      }
  
      @Override
      public void setLongPressDragEnabled(boolean enabled) {
          this.mLongPressEnabled = enabled;
      }
  
      @Override
      public void startDrag(@NonNull RecyclerView.ViewHolder viewHolder) {
          if (isDraggable) {
              mItemTouchHelper.startDrag(viewHolder);
          }
      }
  
      @Override
      public boolean isDraggable() {
          return this.isDraggable;
      }
  
      @Override
      public void setDraggable(boolean draggable) {
          this.isDraggable = draggable;
      }
  
      @Override
      public void setDragExcluded(@NonNull RecyclerView.ViewHolder viewHolder, boolean isExcluded) {
          if (viewHolder.itemView == null) {
              if (WXEnvironment.isApkDebugable()) {
                  WXLogUtils.e(TAG, "[error] viewHolder.itemView is null");
              }
              return;
          }
          if (isExcluded) {
              viewHolder.itemView.setTag(TAG_EXCLUDED);
          } else {
              viewHolder.itemView.setTag(null);
          }
      }
  
      @Override
      public boolean isDragExcluded(@NonNull RecyclerView.ViewHolder viewHolder) {
          if (viewHolder.itemView == null) {
              if (WXEnvironment.isApkDebugable()) {
                  WXLogUtils.e(TAG, "[error] viewHolder.itemView is null");
              }
              return false;
          }
          return viewHolder.itemView.getTag() != null && TAG_EXCLUDED.equals(viewHolder.itemView.getTag());
      }
  
      private Map<String, Object> buildEvent(@Nullable String target, int fromIndex, int toIndex) {
          Map<String, Object> args = new HashMap<>(4);
          args.put("target", target == null ? "unknown" : target);
          args.put("fromIndex", fromIndex);
          args.put("toIndex", toIndex);
          args.put("timestamp", System.currentTimeMillis());
          return args;
      }
  }
  