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Neo4j property value system.
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/*
 * Copyright (c) 2002-2019 "Neo4j,"
 * Neo4j Sweden AB [http://neo4j.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.values.virtual;

import java.util.Arrays;
import java.util.Comparator;

import org.neo4j.values.AnyValue;
import org.neo4j.values.AnyValueWriter;
import org.neo4j.values.ValueMapper;
import org.neo4j.values.VirtualValue;

public abstract class PathValue extends VirtualValue
{
    public abstract NodeValue startNode();

    public abstract NodeValue endNode();

    public abstract RelationshipValue lastRelationship();

    public abstract NodeValue[] nodes();

    public abstract RelationshipValue[] relationships();

    @Override
    public boolean equals( VirtualValue other )
    {
        if ( other == null || !(other instanceof PathValue) )
        {
            return false;
        }
        PathValue that = (PathValue) other;
        return size() == that.size() &&
               Arrays.equals( nodes(), that.nodes() ) &&
               Arrays.equals( relationships(), that.relationships() );
    }

    @Override
    public int computeHash()
    {
        NodeValue[] nodes = nodes();
        RelationshipValue[] relationships = relationships();
        int result = nodes[0].hashCode();
        for ( int i = 1; i < nodes.length; i++ )
        {
            result += 31 * (result + relationships[i - 1].hashCode());
            result += 31 * (result + nodes[i].hashCode());
        }
        return result;
    }

    @Override
    public  void writeTo( AnyValueWriter writer ) throws E
    {
        writer.writePath( nodes(), relationships() );
    }

    @Override
    public  T map( ValueMapper mapper )
    {
        return mapper.mapPath( this );
    }

    @Override
    public VirtualValueGroup valueGroup()
    {
        return VirtualValueGroup.PATH;
    }

    @Override
    public int compareTo( VirtualValue other, Comparator comparator )
    {
        if ( other == null || !(other instanceof PathValue) )
        {
            throw new IllegalArgumentException( "Cannot compare different virtual values" );
        }

        PathValue otherPath = (PathValue) other;
        NodeValue[] nodes = nodes();
        RelationshipValue[] relationships = relationships();
        NodeValue[] otherNodes = otherPath.nodes();
        RelationshipValue[] otherRelationships = otherPath.relationships();

        int x = nodes[0].compareTo( otherNodes[0], comparator );
        if ( x == 0 )
        {
            int i = 0;
            int length = Math.min( relationships.length, otherRelationships.length );

            while ( x == 0 && i < length )
            {
                x = relationships[i].compareTo( otherRelationships[i], comparator );
                ++i;
            }

            if ( x == 0 )
            {
                x = Integer.compare( relationships.length, otherRelationships.length );
            }
        }

        return x;
    }

    @Override
    public String toString()
    {
        NodeValue[] nodes = nodes();
        RelationshipValue[] relationships = relationships();
        StringBuilder sb = new StringBuilder( getTypeName() + "{" );
        int i = 0;
        for ( ; i < relationships.length; i++ )
        {
            sb.append( nodes[i] );
            sb.append( relationships[i] );
        }
        sb.append( nodes[i] );
        sb.append( '}' );
        return sb.toString();
    }

    @Override
    public String getTypeName()
    {
        return "Path";
    }

    public ListValue asList()
    {
        NodeValue[] nodes = nodes();
        RelationshipValue[] relationships = relationships();
        int size = nodes.length + relationships.length;
        AnyValue[] anyValues = new AnyValue[size];
        for ( int i = 0; i < size; i++ )
        {
            if ( i % 2 == 0 )
            {
                anyValues[i] = nodes[i / 2];
            }
            else
            {
                anyValues[i] = relationships[i / 2];
            }
        }
        return VirtualValues.list( anyValues );
    }

    public int size()
    {
        return relationships().length;
    }

    public static class DirectPathValue extends PathValue
    {
        private final NodeValue[] nodes;
        private final RelationshipValue[] edges;

        DirectPathValue( NodeValue[] nodes, RelationshipValue[] edges )
        {
            assert nodes != null;
            assert edges != null;
            assert nodes.length == edges.length + 1;

            this.nodes = nodes;
            this.edges = edges;
        }

        @Override
        public NodeValue startNode()
        {
            return nodes[0];
        }

        @Override
        public NodeValue endNode()
        {
            return nodes[nodes.length - 1];
        }

        @Override
        public RelationshipValue lastRelationship()
        {
            assert edges.length > 0;
            return edges[edges.length - 1];
        }

        @Override
        public NodeValue[] nodes()
        {
            return nodes;
        }

        @Override
        public RelationshipValue[] relationships()
        {
            return edges;
        }

    }
}