/**
    * This file Copyright (c) 2018 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.ui.contentapp;
  
  import static info.magnolia.ui.contentapp.FilteringMode.OFF;
  
  import java.util.stream.Stream;
  
  import org.apache.commons.lang3.StringUtils;
  
  import com.vaadin.data.provider.DataProvider;
  import com.vaadin.data.provider.DataProviderWrapper;
  import com.vaadin.data.provider.HierarchicalDataProvider;
  import com.vaadin.data.provider.HierarchicalQuery;
  import com.vaadin.data.provider.Query;
  import com.vaadin.ui.ComboBox;
  import com.vaadin.ui.ItemCaptionGenerator;
  
  /**
   * {@link com.vaadin.data.provider.DataProviderWrapper} that suppresses the wrapped data provider's filtering logic and will post-filter the results with a caption filter in memory..
   *
   * @param <T> type of item
   * @param <F> type of wrapped provider filter
   */
  public class CaptionFilteringDataProviderWrapper<T, F> extends DataProviderWrapper<T, String, F> {
  
      public static <T, F> CaptionFilteringDataProviderWrapper<T, F> wrap(DataProvider<T, F> src) {
          return new CaptionFilteringDataProviderWrapper<>(src);
      }
  
      private FilteringMode filteringMode = OFF;
      private ItemCaptionGenerator<T> itemCaptionGenerator = Object::toString;
  
      private CaptionFilteringDataProviderWrapper(DataProvider<T, F> dataProvider) {
          super(dataProvider);
      }
  
      public CaptionFilteringDataProviderWrapper<T, F> withItemCaptionGenerator(ItemCaptionGenerator<T> itemCaptionGenerator) {
          this.itemCaptionGenerator = itemCaptionGenerator;
          return this;
      }
  
      public CaptionFilteringDataProviderWrapper<T, F> withFilteringMode(FilteringMode filteringMode) {
          this.filteringMode = filteringMode;
          return this;
      }
  
      @Override
      public Stream<T> fetch(Query<T, String> t) {
          final Stream<T> stream;
          if (dataProvider instanceof HierarchicalDataProvider) {
              stream = super.fetch(new HierarchicalQuery<>(t.getFilter().orElse(null), null));
          } else {
              stream = super.fetch(new Query<>(t.getFilter().orElse(null)));
          }
          return stream //All items, The penalty we have here is that we still fetch the whole bunch of items from backend and filter them in place...
                  .filter(item -> getCaptionFilter().test(itemCaptionGenerator.apply(item), t.getFilter().orElse(StringUtils.EMPTY))) //...but we don't have to pass the caption filtering logic and implement this in each and every data provider
                  .skip(t.getOffset())
                  .limit(t.getLimit());
      }
  
      @Override
      public int size(Query<T, String> t) {
          return (int) fetch(t).count();
      }
  
      /**
       * @return null as we don't modify the filter here (Vaadin way) but implement filtering in {@link #fetch(com.vaadin.data.provider.Query)}.
      */
     @Override
     protected F getFilter(Query<T, String> query) {
         return null;
     }
 
     private ComboBox.CaptionFilter getCaptionFilter() {
         switch (filteringMode) {
         case CONTAINS:
             return StringUtils::containsIgnoreCase;
         case STARTSWITH:
             return StringUtils::startsWithIgnoreCase;
         default:
             return (itemCaption, filterText) -> true;
         }
     }
 
 }