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package org.netbeans.modules.visual.graph.layout.hierarchicalsupport;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import org.netbeans.modules.visual.graph.layout.hierarchicalsupport.DirectedGraph.DummyVertex;
import org.netbeans.modules.visual.graph.layout.hierarchicalsupport.DirectedGraph.Edge;
import org.netbeans.modules.visual.graph.layout.hierarchicalsupport.DirectedGraph.Vertex;

/**
 *
 * @author ptliu
 */
public class VertexInsertionLayerAssigner {
    
    /**
     * Creates a new instance of VertexInsertionLayerAssigner 
     */
    public VertexInsertionLayerAssigner() {
    }
    
    /**
     *
     *
     */
    public LayeredGraph assignLayers(DirectedGraph graph) {
        LayeredGraph layeredGraph = LayeredGraph.createGraph(graph);
        
        insertDummyVertices(layeredGraph);
        
        return layeredGraph;
    }
    

    /**
     *
     *
     */
    private void insertDummyVertices(LayeredGraph graph) {
        DirectedGraph originalGraph = graph.getOriginalGraph();
        List<List<Vertex>> layers = graph.getLayers();
        
        for (int i = 0; i < layers.size(); i++) {
            List<Vertex> layer = layers.get(i);
            
            for (Vertex v : layer) {
                int layerIndex = v.getNumber();
                
                // work around concurrent modification exception
                Collection<Edge> edges = new ArrayList<Edge>(v.getOutgoingEdges());
                for (Edge e : edges) {
                    Vertex nv = e.getTarget();
                    int nvLayerIndex = nv.getNumber();
                    
                    if (nvLayerIndex > layerIndex+1) {
                        Vertex dummyVertex = originalGraph.insertDummyVertex(e, DummyVertex.Type.BEND);
                        graph.assignLayer(dummyVertex,  layerIndex+1);
                    }
                }
            }
        }
    }   
}
