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/*
 * Copyright (c) 2002-2015 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.graphdb.traversal;

import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Path;
import org.neo4j.graphdb.Relationship;

/**
 * Utilities for {@link org.neo4j.graphdb.Path} objects.
 */
public class Paths
{
    /**
     * Provides hooks to help build a string representation of a {@link org.neo4j.graphdb.Path}.
     * @param  the type of {@link org.neo4j.graphdb.Path}.
     */
    public interface PathDescriptor
    {
        /**
         * Returns a string representation of a {@link org.neo4j.graphdb.Node}.
         * @param path the {@link Path} we're building a string representation
         * from.
         * @param node the {@link org.neo4j.graphdb.Node} to return a string representation of.
         * @return a string representation of a {@link org.neo4j.graphdb.Node}.
         */
        String nodeRepresentation( T path, Node node );

        /**
         * Returns a string representation of a {@link org.neo4j.graphdb.Relationship}.
         * @param path the {@link Path} we're building a string representation
         * from.
         * @param from the previous {@link Node} in the path.
         * @param relationship the {@link org.neo4j.graphdb.Relationship} to return a string
         * representation of.
         * @return a string representation of a {@link org.neo4j.graphdb.Relationship}.
         */
        String relationshipRepresentation( T path, Node from,
                                           Relationship relationship );
    }

    /**
     * The default {@link PathDescriptor} used in common toString()
     * representations in classes implementing {@link Path}.
     * @param  the type of {@link Path}.
     */
    public static class DefaultPathDescriptor implements PathDescriptor
    {
        @Override
        public String nodeRepresentation( Path path, Node node )
        {
            return "(" + node.getId() + ")";
        }

        @Override
        public String relationshipRepresentation( Path path,
                                                  Node from, Relationship relationship )
        {
            String prefix = "--", suffix = "--";
            if ( from.equals( relationship.getEndNode() ) )
            {
                prefix = "<--";
            }
            else
            {
                suffix = "-->";
            }
            return prefix + "[" + relationship.getType().name() + "," +
                    relationship.getId() + "]" + suffix;
        }
    }

    /**
     * Method for building a string representation of a {@link Path}, using
     * the given {@code builder}.
     * @param  the type of {@link Path}.
     * @param path the {@link Path} to build a string representation of.
     * @param builder the {@link PathDescriptor} to get
     * {@link Node} and {@link Relationship} representations from.
     * @return a string representation of a {@link Path}.
     */
    public static  String pathToString( T path, PathDescriptor builder )
    {
        Node current = path.startNode();
        StringBuilder result = new StringBuilder();
        for ( Relationship rel : path.relationships() )
        {
            result.append( builder.nodeRepresentation( path, current ) );
            result.append( builder.relationshipRepresentation( path, current, rel ) );
            current = rel.getOtherNode( current );
        }
        if ( null != current ) {
            result.append(builder.nodeRepresentation(path, current));
        }
        return result.toString();
    }

    /**
     * TODO: This method re-binds nodes and relationships. It should not.
     *
     * Returns the default string representation of a {@link Path}. It uses
     * the {@link DefaultPathDescriptor} to get representations.
     * @param path the {@link Path} to build a string representation of.
     * @return the default string representation of a {@link Path}.
     */
    public static String defaultPathToString( Path path )
    {
        return pathToString( path, new DefaultPathDescriptor<>() );
    }

    /**
     * Returns a quite simple string representation of a {@link Path}. It
     * doesn't print relationship types or ids, just directions.
     * @param path the {@link Path} to build a string representation of.
     * @return a quite simple representation of a {@link Path}.
     */
    public static String simplePathToString( Path path )
    {
        return pathToString( path, new DefaultPathDescriptor()
        {
            @Override
            public String relationshipRepresentation( Path path, Node from,
                                                      Relationship relationship )
            {
                return relationship.getStartNode().equals( from ) ? "-->" : "<--";
            }
        } );
    }

    /**
     * Returns a quite simple string representation of a {@link Path}. It
     * doesn't print relationship types or ids, just directions. it uses the
     * {@code nodePropertyKey} to try to display that property value as in the
     * node representation instead of the node id. If that property doesn't
     * exist, the id is used.
     * @param path the {@link Path} to build a string representation of.
     * @return a quite simple representation of a {@link Path}.
     */
    public static String simplePathToString( Path path, final String nodePropertyKey )
    {
        return pathToString( path, new DefaultPathDescriptor()
        {
            @Override
            public String nodeRepresentation( Path path, Node node )
            {
                return "(" + node.getProperty( nodePropertyKey, node.getId() ) + ")";
            }

            @Override
            public String relationshipRepresentation( Path path, Node from,
                                                      Relationship relationship )
            {
                return relationship.getStartNode().equals( from ) ? "-->" : "<--";
            }
        } );
    }
}