/*
 * Copyright 2015 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
*/

package org.eclipse.webdav.dom;

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

/**
 * An element editor for the WebDAV propertybehavior element. See
 * RFC2518 section 12.12 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>
 */
public class PropertyBehavior extends ElementEditor {
    /**
     * An ordered collection of the element names of the
     * propertybehavior element's children.
     */
    protected static final String[] childNames = new String[] {"omit", "keepalive"}; //$NON-NLS-1$ //$NON-NLS-2$

    /**
     * An ordered collection of the element names of the
     * propertybehavior element's children in the "omit" form
     */
    public static String[] fgNamesOmit = new String[] {"omit"}; //$NON-NLS-1$

    /**
     * An ordered collection of the element names of the
     * propertybehavior element's children in the "keep alive" form
     */
    public static String[] fgNamesKeepAlive = new String[] {"keepalive"}; //$NON-NLS-1$

    /**
     * Creates a new editor on the given WebDAV propertybehavior element.
     * The element is assumed to be well formed.
     *
     * @param root a propertybehavior element
     * @throws        MalformedElementException if there is reason to
     *                believe that the element is not well formed
     */
    public PropertyBehavior(Element root) throws MalformedElementException {
        super(root, "propertybehavior"); //$NON-NLS-1$
    }

    /**
     * Adds the given property href to this propertybehavior's list of live
     * properties. The property href must not be <code>null</code> and the
     * form of this property behavior must not already be omit or
     * keepAllAlive.
     *
     * @param propertyHref the property href to add
     */
    public void addProperty(String propertyHref) {
        Assert.isNotNull(propertyHref);
        Assert.isTrue(getFirstChild(root, "omit") == null); //$NON-NLS-1$
        Element keepalive = getFirstChild(root, "keepalive"); //$NON-NLS-1$
        if (keepalive == null)
            keepalive = addChild(root, "keepalive", fgNamesKeepAlive, true); //$NON-NLS-1$
        else
            Assert.isTrue(!"*".equals(getFirstText(keepalive))); //$NON-NLS-1$
        addChild(keepalive, "href", //$NON-NLS-1$
                encodeHref(propertyHref), new String[] {"href"}, //$NON-NLS-1$
                false);
    }

    /**
     * Creates a new WebDAV propertybehavior element and sets it as the root
     * of the given document. Returns an editor on the new propertybehavior
     * element. The document must not be <code>null</code>, and must not
     * already have a root element.
     *
     * @param document the document that will become the root of a new
     *                 propertybehavior element
     * @return         an element editor on a propertybehavior element
     */
    public static PropertyBehavior create(Document document) {
        Assert.isNotNull(document);
        Assert.isTrue(document.getOwnerDocument() == null);
        Element element = create(document, "propertybehavior"); //$NON-NLS-1$
        PropertyBehavior result = null;
        try {
            result = new PropertyBehavior(element);
        } catch (MalformedElementException e) {
            Assert.isTrue(false, Policy.bind("assert.internalError")); //$NON-NLS-1$
        }
        return result;
    }

    /**
     * Returns an <code>Enumeration</code> over this propertybehavior's
     * property hrefs. The methods <code>isMerge()</code> and
     * <code>isKeepAllAlive</code> return false if this propertybehavior is
     * in the "keep some alive" form.
     *
     * @return an <code>Enumeration</code> of <code>String</code>s
     * @throws MalformedElementException if there is reason to believe that
     *         this editor's underlying element is not well formed, or this
     *         propertybehavior is not in the "keep some alive" form
     * @see    #isKeepAllAlive()
     * @see    #isOmit()
     */
    public Enumeration getProperties() throws MalformedElementException {

        Element keepalive = getFirstChild(root, "keepalive"); //$NON-NLS-1$
        ensureNotNull(Policy.bind("ensure.missingKeealiveElmt"), keepalive); //$NON-NLS-1$
        ensure(!"*".equals(getFirstText(keepalive)), //$NON-NLS-1$
                Policy.bind("ensure.wrongForm")); //$NON-NLS-1$

        final Element firstHref = getFirstChild(keepalive, "href"); //$NON-NLS-1$
        ensureNotNull(Policy.bind("ensure.missingHrefElmt"), firstHref); //$NON-NLS-1$

        Enumeration e = new Enumeration() {
            Element currentHref = firstHref;

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

            public Object nextElement() {
                if (!hasMoreElements())
                    throw new NoSuchElementException();
                String href = getFirstText(currentHref);
                currentHref = getTwin(currentHref, true);
                return decodeHref(href);
            }
        };

        return e;
    }

    /**
     * Returns <code>true</code> if this propertybehavior is in the
     * "keep all alive" form, otherwise, returns <code>false</code>.
     *
     * @return a boolean indicating whether this propertybehavior is in the
     *         "keep all alive" form or not
     * @throws MalformedElementException if there is reason to believe that
     *         this editor's underlying element is not well formed
     */
    public boolean isKeepAllAlive() throws MalformedElementException {
        Element child = getFirstChild(root, childNames);
        ensureNotNull(Policy.bind("ensure.expectingOmitOrKeepaliveElmt"), child); //$NON-NLS-1$
        boolean isKeepAllAlive = false;
        if (isDAVElement(child, "keepalive")) { //$NON-NLS-1$
            isKeepAllAlive = "*".equals(getFirstText(child)); //$NON-NLS-1$
            ensureNull(Policy.bind("ensure.conflictingHrefElmt"), getFirstChild(child, "href")); //$NON-NLS-1$ //$NON-NLS-2$
        }
        child = getNextSibling(child, childNames);
        ensureNull(Policy.bind("ensure.conflictingOmitOrKeepaliveElmt"), child); //$NON-NLS-1$
        return isKeepAllAlive;
    }

    /**
     * Returns <code>true</code> if this propertybehavior is in the
     * "omit" form, otherwise, returns <code>false</code>.
     *
     * @return a boolean indicating whether this propertybehavior is in the
     *         "omit" form or not
     * @throws MalformedElementException if there is reason to believe that
     *         this editor's underlying element is not well formed
     */
    public boolean isOmit() throws MalformedElementException {
        Element child = getFirstChild(root, childNames);
        ensureNotNull(Policy.bind("ensure.expectingOmitOrKeepaliveElmt"), child); //$NON-NLS-1$
        boolean isOmit = isDAVElement(child, "omit"); //$NON-NLS-1$
        child = getNextSibling(child, childNames);
        ensureNull(Policy.bind("ensure.conflictingOmitOrKeepaliveElmt"), child); //$NON-NLS-1$
        return isOmit;
    }

    /**
     * Sets whether this propertybehavior is in the "keep all alive" form or
     * not.
     *
     * @param isKeepAllAlive a boolean indicating whether this
     *                       propertybehavior will be in the "keep all
     *                       alive" form
     */
    public void setIsKeepAllAlive(boolean isKeepAllAlive) {
        Element child = getFirstChild(root, childNames);
        boolean isAlreadyKeepAllAlive = false;
        if (isDAVElement(child, "keepalive")) //$NON-NLS-1$
            isAlreadyKeepAllAlive = "*".equals(getFirstText(child)); //$NON-NLS-1$
        if (isKeepAllAlive) {
            if (!isAlreadyKeepAllAlive) {
                if (child != null)
                    root.removeChild(child);
                appendChild(root, "keepalive", "*"); //$NON-NLS-1$ //$NON-NLS-2$
            }
        } else if (isAlreadyKeepAllAlive)
            root.removeChild(child);
    }

    /**
     * Sets whether this propertybehavior is in the "omit" form or not.
     *
     * @param isOmit a boolean indicating whether this propertybehavior will
     *               be in the "omit" form
     */
    public void setIsOmit(boolean isOmit) {
        Element child = getFirstChild(root, childNames);
        boolean isAlreadyOmit = isDAVElement(child, "omit"); //$NON-NLS-1$
        if (isOmit) {
            if (!isAlreadyOmit) {
                if (child != null)
                    root.removeChild(child);
                appendChild(root, "omit"); //$NON-NLS-1$
            }
        } else if (isAlreadyOmit)
            root.removeChild(child);
    }
}
