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/*
 * Created on Oct 17, 2005
 *
 * Copyright (c) 2005, The JUNG Authors 
 *
 * All rights reserved.
 *
 * This software is open-source under the BSD license; see either
 * "license.txt" or
 * https://github.com/jrtom/jung/blob/master/LICENSE for a description.
 */
package edu.uci.ics.jung.graph;

import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Set;

import com.google.common.base.Supplier;

import edu.uci.ics.jung.graph.util.Pair;


/**
 * An implementation of DirectedGraph, suitable for sparse graphs, 
 * that orders its vertex and edge collections
 * according to insertion time.
 */
@SuppressWarnings("serial")
public class DirectedOrderedSparseMultigraph 
    extends DirectedSparseMultigraph
    implements DirectedGraph, MultiGraph 
{
    /**
     * @param  the vertex type for the graph Supplier
     * @param  the edge type for the graph Supplier
     * @return a {@code Supplier} that creates an instance of this graph type.
     */
	public static  Supplier> getFactory() {
		return new Supplier> () {
			public DirectedGraph get() {
				return new DirectedOrderedSparseMultigraph();
			}
		};
	}

    /**
     * Creates a new instance.
     */
    public DirectedOrderedSparseMultigraph() {
        vertices = new LinkedHashMap>>();
        edges = new LinkedHashMap>();
    }
    
    @Override
    public boolean addVertex(V vertex) {
    	if(vertex == null) {
    		throw new IllegalArgumentException("vertex may not be null");
    	}
        if (!containsVertex(vertex)) {
            vertices.put(vertex, new Pair>(new LinkedHashSet(), new LinkedHashSet()));
            return true;
        } else {
            return false;
        }
    }

    @Override
    public Collection getPredecessors(V vertex) {
        if (!containsVertex(vertex)) 
            return null;
        Set preds = new LinkedHashSet();
        for (E edge : getIncoming_internal(vertex))
            preds.add(this.getSource(edge));
        
        return Collections.unmodifiableCollection(preds);
    }

    @Override
    public Collection getSuccessors(V vertex) {
        if (!containsVertex(vertex)) 
            return null;
        Set succs = new LinkedHashSet();
        for (E edge : getOutgoing_internal(vertex))
            succs.add(this.getDest(edge));
        
        return Collections.unmodifiableCollection(succs);
    }

    @Override
    public Collection getNeighbors(V vertex) {
        if (!containsVertex(vertex)) 
            return null;
        Collection neighbors = new LinkedHashSet();
        for (E edge : getIncoming_internal(vertex))
            neighbors.add(this.getSource(edge));
        for (E edge : getOutgoing_internal(vertex))
            neighbors.add(this.getDest(edge));
        return Collections.unmodifiableCollection(neighbors);
    }

    @Override
    public Collection getIncidentEdges(V vertex) {
        if (!containsVertex(vertex)) 
            return null;
        Collection incident = new LinkedHashSet();
        incident.addAll(getIncoming_internal(vertex));
        incident.addAll(getOutgoing_internal(vertex));
        return incident;
    }

}