package org.wamblee.xml;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * Utility class for performing various operations on DOM trees.
 */
public final class DOMUtility {

    /**
     * Disabled constructor.
     * 
     */
    private DOMUtility() {
        // Empty
    }

    /**
     * Removes duplicate attributes from a DOM tree.
     * 
     * @param aNode
     *            Node to remove duplicate attributes from (recursively).
     *            Attributes of the node itself are not dealt with. Only the
     *            child nodes are dealt with.
     */
    public static void removeDuplicateAttributes(Node aNode) {
        NodeList list = aNode.getChildNodes();
        for (int i = 0; i < list.getLength(); i++) {
            Node node = list.item(i);
            if (node instanceof Element) {
                removeDuplicateAttributes((Element) node);
                removeDuplicateAttributes(node);
            }
        }
    }

    /**
     * Removes duplicate attributes from an element.
     * 
     * @param aElement
     *            Element.
     */
    private static void removeDuplicateAttributes(Element aElement) {
        NamedNodeMap attributes = aElement.getAttributes();
        Map<String, Attr> uniqueAttributes = new TreeMap<String, Attr>();
        List<Attr> attlist = new ArrayList<Attr>();
        for (int i = 0; i < attributes.getLength(); i++) {
            Attr attribute = (Attr) attributes.item(i);
            if (uniqueAttributes.containsKey(attribute.getNodeName())) {
                System.out.println("Detected duplicate attribute '"
                        + attribute.getNodeName() + "'");
            }
            uniqueAttributes.put(attribute.getNodeName(), attribute);
            attlist.add(attribute);
        }
        // Remove all attributes from the element.
        for (Attr att : attlist) {
            aElement.removeAttributeNode(att);
        }
        // Add the unique attributes back to the element.
        for (Attr att : uniqueAttributes.values()) {
            aElement.setAttributeNode(att);
        }
    }
}