package prefuse.controls;

import java.awt.event.MouseEvent;
import java.util.Iterator;

import prefuse.visual.EdgeItem;
import prefuse.visual.NodeItem;
import prefuse.visual.VisualItem;


/**
 * <p>
 * A ControlListener that sets the highlighted status (using the
 * {@link prefuse.visual.VisualItem#setHighlighted(boolean)
 * VisualItem.setHighlighted} method) for nodes neighboring the node 
 * currently under the mouse pointer. The highlight flag might then be used
 * by a color function to change node appearance as desired.
 * </p>
 *
 * @author <a href="http://jheer.org">jeffrey heer</a>
 */
public class NeighborHighlightControl extends ControlAdapter {

    private String activity = null;
    private boolean highlightWithInvisibleEdge = false;
    
    /**
     * Creates a new highlight control.
     */
    public NeighborHighlightControl() {
        this(null);
    }
    
    /**
     * Creates a new highlight control that runs the given activity
     * whenever the neighbor highlight changes.
     * @param activity the update Activity to run
     */
    public NeighborHighlightControl(String activity) {
        this.activity = activity;
    }
    
    /**
     * @see prefuse.controls.Control#itemEntered(prefuse.visual.VisualItem, java.awt.event.MouseEvent)
     */
    public void itemEntered(VisualItem item, MouseEvent e) {
        if ( item instanceof NodeItem )
            setNeighborHighlight((NodeItem)item, true);
    }
    
    /**
     * @see prefuse.controls.Control#itemExited(prefuse.visual.VisualItem, java.awt.event.MouseEvent)
     */
    public void itemExited(VisualItem item, MouseEvent e) {
        if ( item instanceof NodeItem )
            setNeighborHighlight((NodeItem)item, false);
    }
    
    /**
     * Set the highlighted state of the neighbors of a node.
     * @param n the node under consideration
     * @param state the highlighting state to apply to neighbors
     */
    protected void setNeighborHighlight(NodeItem n, boolean state) {
        Iterator iter = n.edges();
        while ( iter.hasNext() ) {
            EdgeItem eitem = (EdgeItem)iter.next();
            NodeItem nitem = eitem.getAdjacentItem(n);
            if (eitem.isVisible() || highlightWithInvisibleEdge) {
                eitem.setHighlighted(state);
                nitem.setHighlighted(state);
            }
        }
        if ( activity != null )
            n.getVisualization().run(activity);
    }
    
    /**
     * Indicates if neighbor nodes with edges currently not visible still
     * get highlighted.
     * @return true if neighbors with invisible edges still get highlighted,
     * false otherwise.
     */
    public boolean isHighlightWithInvisibleEdge() {
        return highlightWithInvisibleEdge;
    }
   
    /**
     * Determines if neighbor nodes with edges currently not visible still
     * get highlighted.
     * @param highlightWithInvisibleEdge assign true if neighbors with invisible
     * edges should still get highlighted, false otherwise.
     */
    public void setHighlightWithInvisibleEdge(boolean highlightWithInvisibleEdge) {
        this.highlightWithInvisibleEdge = highlightWithInvisibleEdge;
    }
    
} // end of class NeighborHighlightControl