/**
 * This software is licensed to you under the Apache License, Version 2.0 (the
 * "Apache License").
 *
 * LinkedIn's contributions are made under the Apache License. If you contribute
 * to the Software, the contributions will be deemed to have been made under the
 * Apache License, unless you expressly indicate otherwise. Please do not make any
 * contributions that would be inconsistent with the Apache License.
 *
 * You may obtain a copy of the Apache License at http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, this software
 * distributed under the Apache License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the Apache
 * License for the specific language governing permissions and limitations for the
 * software governed under the Apache License.
 *
 * © 2012 LinkedIn Corp. All Rights Reserved.  
 */
package com.senseidb.indexing;

import java.io.IOException;
import java.util.List;

import com.browseengine.bobo.api.BoboIndexReader;
import com.browseengine.bobo.api.BrowseSelection;
import com.browseengine.bobo.facets.FacetHandler;
import com.browseengine.bobo.facets.filter.EmptyFilter;
import com.browseengine.bobo.facets.filter.RandomAccessFilter;
import com.senseidb.search.req.SenseiRequest;

public interface SenseiIndexPruner {
	
	IndexReaderSelector getReaderSelector(SenseiRequest req);

  void sort(List<BoboIndexReader> readers);
 
	public interface IndexReaderSelector{
		boolean isSelected(BoboIndexReader reader) throws IOException;
	}
	
	public static class DefaultSenseiIndexPruner implements SenseiIndexPruner{

		@Override
		public IndexReaderSelector getReaderSelector(SenseiRequest req) {
			return new IndexReaderSelector(){

				@Override
				public boolean isSelected(BoboIndexReader reader)
						throws IOException {
					return true;
				}
				
			};
		}

    @Override
    public void sort(List<BoboIndexReader> readers) {
      // do nothing
    }
	}
	
	public static class BoboSelectionSenseiIndexPruner implements SenseiIndexPruner{

		@Override
		public IndexReaderSelector getReaderSelector(final SenseiRequest req) {
			return new IndexReaderSelector(){

				@Override
				public boolean isSelected(BoboIndexReader reader)
						throws IOException {
					BrowseSelection[] selections = req.getSelections();
					boolean valid = true;
					if (selections!=null){
						for (BrowseSelection sel : selections){
							String name = sel.getFieldName();
							FacetHandler<?> handler = reader.getFacetHandler(name);
							if (handler!=null){
								RandomAccessFilter filter = handler.buildFilter(sel);
								if (EmptyFilter.getInstance() == filter){
									valid = false;
									break;
								}
							}
						}
					}
					return valid;
				}
				
			};
		}

    @Override
    public void sort(List<BoboIndexReader> readers) {
      // do nothing
    }
	}
}