/* Copyright (C) 2004-2007  Ulrich Bauer <ulrich.bauer@alumni.tum.de>
 *
 * Contact: cdk-devel@lists.sourceforge.net
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 * All we ask is that proper credit is given for our work, which includes
 * - but is not limited to - adding the above copyright notice to the beginning
 * of your source code files, and to any copyright notice that you may distribute
 * with programs based on this work.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */
package org.openscience.cdk.graph;

import org._3pq.jgrapht.Edge;
import org._3pq.jgrapht.Graph;
import org._3pq.jgrapht.traverse.BreadthFirstIterator;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * Utility class that finds the shortest bond path between two atoms using
 * a breadth first search.
 *
 * @author Ulrich Bauer &lt;ulrich.bauer@alumni.tum.de&gt;
 *
 * @cdk.module  standard
 * @cdk.githash
 * @cdk.created 2004-10-19
 * @deprecated Use {@link ShortestPaths}
 */
@Deprecated
public final class BFSShortestPath {

    private BFSShortestPath() {} // ensure non-instantiability.

    public static List<Edge> findPathBetween(Graph graph, Object startVertex, Object endVertex) {
        MyBreadthFirstIterator iter = new MyBreadthFirstIterator(graph, startVertex);

        while (iter.hasNext()) {
            Object vertex = iter.next();

            if (vertex.equals(endVertex)) {
                return createPath(iter, endVertex);
            }
        }

        return null;
    }

    private static List<Edge> createPath(MyBreadthFirstIterator iter, Object endVertex) {
        List<Edge> path = new ArrayList<Edge>();

        while (true) {
            Edge edge = iter.getSpanningTreeEdge(endVertex);

            if (edge == null) {
                break;
            }

            path.add(edge);
            endVertex = edge.oppositeVertex(endVertex);
        }

        Collections.reverse(path);

        return path;
    }

    private static class MyBreadthFirstIterator extends BreadthFirstIterator {

        public MyBreadthFirstIterator(Graph g, Object startVertex) {
            super(g, startVertex);
        }

        @Override
        protected void encounterVertex(Object vertex, Edge edge) {
            super.encounterVertex(vertex, edge);
            putSeenData(vertex, edge);
        }

        public Edge getSpanningTreeEdge(Object vertex) {
            return (Edge) getSeenData(vertex);
        }

    }
}
