/*
    * 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.chemistry.opencmis.client.runtime.util;
  
  import java.util.List;
  
  import org.apache.chemistry.opencmis.client.runtime.util.AbstractPageFetcher.Page;
  
  /**
   * Iterator for iterating over all items in a CMIS Collection.
   *
   * @param <T>
   */
  public class CollectionIterator<T> extends AbstractIterator<T> {
  
      /**
       * Constructor.
       */
      public CollectionIterator(long skipCount, AbstractPageFetcher<T> pageFetcher) {
          super(skipCount, pageFetcher);
      }
  
      @Override
      public boolean hasNext() {
          Page<T> page = getCurrentPage();
          if (page == null) {
              return false;
          }
  
          List<T> items = page.getItems();
          if (items == null || items.isEmpty()) {
              return false;
          }
  
          if (getSkipOffset() < items.size()) {
              return true;
          }
  
          if (!getHasMoreItems()) {
              return false;
          }
  
          long totalItems = getTotalNumItems();
          if (totalItems < 0) {
              // we don't know better
              return true;
          }
  
          return (getSkipCount() + getSkipOffset()) < totalItems;
      }
  
      @Override
      public T next() {
          Page<T> page = getCurrentPage();
          if (page == null) {
              return null;
          }
  
          List<T> items = page.getItems();
          if (items == null || items.isEmpty()) {
              return null;
          }
  
          if (getSkipOffset() == items.size()) {
              page = incrementPage();
              items = page == null ? null : page.getItems();
          }
  
          if (items == null || items.isEmpty() || getSkipOffset() == items.size()) {
              return null;
          }
  
          return items.get(incrementSkipOffset());
      }
  
  }