/*******************************************************************************
 * Copyright 2014 University of Southern California
 * 
 * Licensed 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.
 * 
 * This code was developed by the Information Integration Group as part 
 * of the Karma project at the Information Sciences Institute of the 
 * University of Southern California.  For more information, publications, 
 * and related projects, please see: http://www.isi.edu/integration
 ******************************************************************************/
package edu.isi.karma.kr2rml.planning;

import java.util.Set;

import edu.isi.karma.kr2rml.template.ColumnTemplateTerm;

public class WorksheetDepthRootStrategy extends RootStrategy {

	public WorksheetDepthRootStrategy()
	{
		super(new RootStrategy());
	}
	public WorksheetDepthRootStrategy(
			RootStrategy backupStrategy) {
		super(backupStrategy);
	}
	
	@Override
	public String findRoot(TriplesMapGraph graph) {
		Set<String> triplesMapIds = graph.getTriplesMapIds();
		int minDepth = Integer.MAX_VALUE;
		String root = null;
		for(String triplesMapId : triplesMapIds)
		{
			TriplesMap map = graph.getTriplesMap(triplesMapId);
			int depth = ColumnTemplateTerm.calculateMaximumColumnPathLength(map.getSubject().getTemplate().getAllColumnNameTermElements());
			if(depth < minDepth)
			{
				minDepth = depth;
				root = triplesMapId;
			}
		}
		if(root == null)
		{
			return backupStrategy.findRoot(graph);
		}
		return root;
	}

}
