/*
 * Copyright 2008 the original author or authors.
 * 
 * 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.
 */
package org.wamblee.system.graph;

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

public class Graph {

    private List<Node> _nodes;
    private List<Edge> _edges;

    public Graph() {
        _nodes = new ArrayList<Node>();
        _edges = new ArrayList<Edge>();
    }

    public void addNode(Node aNode) {
        if (_nodes.contains(aNode)) {
            throw new IllegalArgumentException("Node '" + aNode.getName()
                    + "' already exists");
        }
        _nodes.add(aNode);
    }
    
    public Node findNode(String aName) { 
        for (Node node: _nodes) { 
            if ( node.getName().equals(aName)) { 
                return node; 
            }
        }
        return null; 
    }

    public boolean removeNode(Node aNode) {
        if (!findOutgoing(aNode).isEmpty() || !findIncoming(aNode).isEmpty()) {
            throw new IllegalArgumentException("Cannot remove node '"
                    + aNode.getName()
                    + "' because it is connected to one or more edges");
        }
        return _nodes.remove(aNode);
    }

    public void addNodes(List<Node> aNodes) {
        for (Node node : aNodes) {
            addNode(node);
        }
    }

    public void addEdge(Edge aEdge) {
        if (_edges.contains(aEdge)) {
            throw new IllegalArgumentException("Edge '" + aEdge
                    + "' already exists");
        }
        if (!_nodes.contains(aEdge.getFrom())) {
            throw new IllegalArgumentException("From node '" + aEdge.getFrom()
                    + "' from edge '" + aEdge + "' is not part of the graph");
        }
        if (!_nodes.contains(aEdge.getTo())) {
            throw new IllegalArgumentException("To node '" + aEdge.getTo()
                    + "' from edge '" + aEdge + "' is not part of the graph");
        }
        _edges.add(aEdge);
    }

    public boolean removeEdge(Edge aEdge) {
        return _edges.remove(aEdge);
    }

    public void addEdges(List<Edge> aEdges) {
        for (Edge edge : aEdges) {
            addEdge(edge);
        }
    }

    public List<Node> getNodes() {
        return new ArrayList<Node>(_nodes);
    }

    public List<Edge> getEdges() {
        return new ArrayList<Edge>(_edges);
    }

    public void extend(EdgeFactory aFactory) {
        for (Node from : _nodes) {
            for (Node to : _nodes) {
                _edges.addAll(aFactory.create(from, to));
            }
        }
    }

    public List<Edge> findOutgoing(Node aNode) {
        List<Edge> result = new ArrayList<Edge>();
        for (Edge edge : _edges) {
            if (edge.getFrom().getName().equals(aNode.getName())) {
                result.add(edge);
            }
        }
        return result;
    }

    public List<Edge> findIncoming(Node aNode) {
        List<Edge> result = new ArrayList<Edge>();
        for (Edge edge : _edges) {
            if (edge.getTo().getName().equals(aNode.getName())) {
                result.add(edge);
            }
        }
        return result;
    }

    public void accept(Visitor aVisitor) {
        List<Node> nodes = getNodes(); // copy to make sure the visitor can
                                        // modify the
        // list of nodes as part of the loop.
        List<Edge> edges = getEdges(); // copy ..... (see above).

        for (Node node : nodes) {
            aVisitor.visitNode(node);
        }
        for (Edge edge : edges) {
            aVisitor.visitEdge(edge);
        }
    }
}