package org.argeo.eclipse.ui.jcr.lists;
   
   import javax.jcr.Node;
   import javax.jcr.RepositoryException;
   import javax.jcr.query.Row;
   
   import org.argeo.eclipse.ui.EclipseUiException;
   import org.eclipse.jface.viewers.Viewer;
   
  /**
   * Base comparator to enable ordering on Table or Tree viewer that display Jcr
   * rows
   */
  public class RowViewerComparator extends NodeViewerComparator {
  	private static final long serialVersionUID = 7020939505172625113L;
  	protected String selectorName;
  
  	public RowViewerComparator() {
  	}
  
  	/**
  	 * e1 and e2 must both be Jcr rows.
  	 * 
  	 * @param viewer
  	 * @param e1
  	 * @param e2
  	 * @return
  	 */
  	@Override
  	public int compare(Viewer viewer, Object e1, Object e2) {
  		try {
  			Node n1 = ((Row) e1).getNode(selectorName);
  			Node n2 = ((Row) e2).getNode(selectorName);
  			return super.compare(viewer, n1, n2);
  		} catch (RepositoryException re) {
  			throw new EclipseUiException("Unexpected error "
  					+ "while comparing nodes", re);
  		}
  	}
  
  	/**
  	 * @param propertyType
  	 *            Corresponding JCR type
  	 * @param propertyName
  	 *            name of the property to use.
  	 */
  	public void setColumn(int propertyType, String selectorName,
  			String propertyName) {
  		if (this.selectorName != null && getPropertyName() != null
  				&& this.selectorName.equals(selectorName)
  				&& this.getPropertyName().equals(propertyName)) {
  			// Same column as last sort; toggle the direction
  			setDirection(1 - getDirection());
  		} else {
  			// New column; do a descending sort
  			setPropertyType(propertyType);
  			setPropertyName(propertyName);
  			this.selectorName = selectorName;
  			setDirection(NodeViewerComparator.ASCENDING);
  		}
  	}
  }