package org.eclipse.webdav.dom;

import java.util.Enumeration;
import java.util.NoSuchElementException;
import org.eclipse.webdav.Policy;
import org.w3c.dom.*;

/**
 * An element editor for the WebDAV prop element. See RFC2518 section
 * 12.11 for the element's definition.
 * <p>
 * <b>Note:</b> This class/interface is part of an interim API that is still under 
 * development and expected to change significantly before reaching stability. 
 * It is being made available at this early stage to solicit feedback from pioneering 
 * adopters on the understanding that any code that uses this API will almost 
 * certainly be broken (repeatedly) as the API evolves.
 * </p>
 *
 * @see PropStat
 * @see PropertyUpdate
 * @see PropFind
 * @see Property
 */
public class Prop extends ElementEditor {
    /**
     * Creates a new editor on the given WebDAV prop element. The element
     * is assumed to be well formed.
     *
     * @param root a prop element
     * @throws        MalformedElementException if there is reason to
     *                believe that the element is not well formed
     */
    public Prop(Element root) throws MalformedElementException {
        super(root, "prop"); //$NON-NLS-1$
    }

    /**
     * Creates a clone of the given element and adds it to this prop. The
     * element must not be <code>null</code>.
     *
     * @param element any element
     * @throws        MalformedElementException if there is reason to
     *                believe that the given element is not well formed
     */
    public void addProperty(Element element) throws MalformedElementException {
        Assert.isNotNull(element);
        extractNode(root, element);
    }

    /**
     * Creates a new element with the given name and adds it to this prop.
     * The name must not be <code>null</code> and its qualifier and local
     * name must not be <code>null</code> and must not be the empty string.
     *
     * @param name the <code>QualifiedName</code> of the property to add
     */
    public void addPropertyName(QualifiedName name) {
        Assert.isNotNull(name);
        String nsName = name.getQualifier();
        Assert.isTrue(!"".equals(nsName)); //$NON-NLS-1$
        String localName = name.getLocalName();
        Assert.isNotNull(localName);
        Assert.isTrue(!localName.equals("")); //$NON-NLS-1$
        Document document = root.getOwnerDocument();
        Element element = document.createElement(localName);
        declareNS(element, null, nsName);
        root.appendChild(element);
    }

    /**
     * Returns an <code>Enumeration</code> over this prop's property
     * <code>Element</code>s.
     *
     * @returns an <code>Enumeration</code> of </code>Element</code>s
     * @throws  MalformedElementException if there is reason to believe that
     *          this editor's underlying element is not well formed
     */
    public Enumeration getProperties() throws MalformedElementException {
        Node firstChild = getChildElement(root, true);
        final Node firstElement = firstChild;
        Enumeration e = new Enumeration() {
            Node currentElement = firstElement;

            public boolean hasMoreElements() {
                return currentElement != null;
            }

            public Object nextElement() {
                if (!hasMoreElements())
                    throw new NoSuchElementException();
                Node nextElement = currentElement;
                currentElement = getNextSibling((Element) currentElement);
                return nextElement;
            }
        };
        return e;
    }

    /**
     * Returns an <code>Enumeration</code> over this prop's property
     * <code>QualifiedName</code>s.
     *
     * @returns an <code>Enumeration</code> of </code>QualifiedName</code>s
     * @throws  MalformedElementException if there is reason to believe that
     *          this editor's underlying element is not well formed
     */
    public Enumeration getPropertyNames() throws MalformedElementException {
        Node firstChild = getChildElement(root, true);
        final Node firstElement = firstChild;
        Enumeration e = new Enumeration() {
            Node currentElement = firstElement;

            public boolean hasMoreElements() {
                return currentElement != null;
            }

            public Object nextElement() {
                if (!hasMoreElements())
                    throw new NoSuchElementException();
                String nsName = null;
                try {
                    nsName = getNSName((Element) currentElement);
                } catch (MalformedElementException ex) {
                    Assert.isTrue(false, Policy.bind("assert.internalError")); //$NON-NLS-1$
                }
                String localName = getNSLocalName((Element) currentElement);
                QualifiedNameImpl name = new QualifiedNameImpl(nsName, localName);
                currentElement = getNextSibling((Element) currentElement);
                return name;
            }
        };
        return e;
    }
}
